Edible Oil Ghee

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The Edible Oil & GheeSector

Environmental Report

DRAFT


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Table of Contents

Preface

Executive Summary

1. Introduction

1.1 Environmental Technology Program for Industry (ETPI)1.2 Demonstration Project1.3 Environmental Problems of Edible Oil Industry of Pakistan

2. The Edible Oil Industry2.1 Raw Material2.2 Process Chemicals2.3 Utilities2.4 Process Description

2.4.1Vegetable Ghee2.4.2Cooking Oil2.4.3Acid Oil2.4.4Carbon Oil2.4.5Soap

3. Environmental Stresses and their Quantification3.1 Wastewater

3.1.1 Sources and Disposal3.1.2 Quantification

3.1.3 Characterisation3.1.4 Pollution Load

3.2 Solid Waste3.3 Soil Contamination3.4 Air Emissions3.5 Noise Emissions3.6 Occupational Health and Safety (OH&S)

3.7 Energy Inefficiency

4. Impacts4.1 Impacts Associated with Wastewater4.2 Impacts Associated with Solid Waste4.3 Impacts Associated with Soil Contamination4.4 Impacts Associated with Air Emissions

4.5 Impacts Associated with Noise4.6 Implication Associated with Occupational Health and Safety4.7 Impact Associated with Energy Wastage

5. Recommendations5.1 Wastewater Reduction & Treatment

5.1.1 Size Optimisation of Separation Chambers

5.1.2 Recycling of washing water after neutralisation5.1.3 Replacement of Gravity Settling by Centrifuge after

Neutralisation5.1.4Use of Pressurised Water for Floor Cleaning5.1.5Improvement of Foam and Soap Removal from Fat

Traps5.1.6Reorganisation of Water Systems5.1.7Use of Flow Meters5.1.8Construction of a Wastewater Treatment Plant

5.2 Solid Waste5.2.1 Improvement of Waste Management and Land Filling

5.2.2 Use of Tankers with Internal Coils to Minimise Sludge5.2.3 Increased Recycling of Nickel Catalysts

5.2.4 Recovery of Oil from Spent Earth

5.3 Soil Contamination Prevention5.4 Air Emissions Control

5.4.1 Recovery of FFA at Deodoriser

5.4.2 Recovery of CO2 from Gas Cracking Plant5.4.3 Optimisation of Combustion at Boiler

5.5 Safety and Health (S&H)5.5.1 Exhaust Combustion Gases out of Gas Cracking

Building5.5.2 Improvement of Noise Abatement and Protection

5.5.3 Improvement of Working Conditions at the Tin Shop5.5.4 Use of Material Safety Data Sheets (MSDS) of Raw

Products

5.6 Energy

5.6.1 Recovery of Heat from Cooling Water Used duringHydrogenation

5.6.2 Pre-heating of Incoming Oil with Outgoing Oil atHydrogenation

5.6.3 Pre-heating of Incoming Oil with Outgoing Oil atDeodorization

5.6.4 Improvement of Steam Pipes Insulation

5.6.5 Increasing Temperature during Deodorization5.6.6 Installation of a Cogeneration Plant

5.7 General Recommendations5.7.1 Inert Atmosphere after Deodorization

5.7.2 Covering of Lye Preparation Area5.7.3 Insulation of Chilling Rooms Doors

5.7.4 Environmental Management Systems (EMS)

LIST OF TABLES

Table 2.1: Edible Oil Local Production and Imports (1995)

Table 2.2: Process Chemicals and their UsageTable 2.3: Utilities and their Consumption

Table 3.1: Daily Wastewater DischargeTable 3.2: Wastewater AnalysisTable 3.3: Daily Pollution Load

Table 3.4: Details of Solid WasteTable 3.5: Air Emission from Different Sources

Table 5.1: Design Data of Primary Treatment SystemTable 5.2: Cost Estimates for Primary Treatment SystemTable 5.3: Design Data of Secondary Treatment System

Table 5.4: Cost Estimates for Secondary Treatment System

LIST OF FIGURES

Figure 2.1: Ghee Process Flow SheetFigure 2.2: Cooking Oil Process Flow Sheet

Figure 5.1: Gravity Settling TankFigure 5.2: Chemically Enhanced Dissolved Air FlotationFigure 5.3: Process Flow Diagram of Activated Sludge System

Figure 5.4: Proposed System for Pre-heating of Incoming Oil with

Outgoing Oil at Hydrogenation


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Preface

This report is a part of the ETPI demonstration projectcomponent. The purpose of this report is to address the

environmental problems of edible oil sector.

The report has been prepared on the basis of the findings of

the environmental audits of three edible oil mills whichwere conducted by ETPI in February, 1998. The study wasjointly carried out by two leading firms of the ETPIconsortium i.e. National Environmental Consulting (Pvt.)

Ltd. and Haskoning Royal Dutch Consulting Engineers andArchitects, The Netherlands.

This report is a step towards the dissemination of

information, about the environmental problems of theedible oil and ghee manufacturing facility along with the

possible solutions and investment required to mitigate these

problems and to comply the present and futureenvironmental legislation.

It is envisaged that this effort will help to enable edible oil

mills to initiate efforts to combat the environmental

problems to produce environmentally clean products.

In addition it is hoped this report would also support theefforts of R&D institutions, environmental equipment and

chemical suppliers, and environmental researchers/studentsworking towards the betterment of the environment.

We acknowledge the participation of PVMA and edible oil

mills in the program and for extending their co-operation inall aspects of the study and thank them for their continuous

support and encouragement.

April, 1999


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Acronyms

BOD Biochemical Oxygen Demand

COD Chemical Oxygen DemandCT Cleaner Technologies

dB DecibelE O P END-OF-PIPE

FFA Free Fatty AcidsGCP Ghee Corporations of Pakistan

IHI In-House ImprovementsMP Melting Point

MT Metric TonNCS National Conservation Strategy

NEQS National Environmental Quality StandardsNG Natural Gas

O&G Oil and GreaseO H & S Occupational Health and Safety

PM Particulate Matter PPM Parts per Million

RBD Refined Bleached and Deodorized

TDS Total Dissolved Solids

th Thermies = 1000 caloriesTSS Total Suspended SolidsVOC Volatile Organic Carbon


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Executive Summary

Environmental degradation by the industrial sector is amatter of serious concern in Pakistan. The Federation of

Pakistan Chambers of Commerce and Industry (FPCCI)with the assistance of the Government of the Netherlands

has undertaken the Environmental Technology Program for

Industry (ETPI) to facilitate the industrial sector inimplementing environmental control projects in Pakistan.This occurs by initiating measures to combat pollution,

thereby, enabling the industries to comply with theNational Environmental Quality Standards (NEQS) and the

forthcoming ISO 14000 certification.

ETPI aims at the implementation of demonstration projectsof environmental cleaner technologies. ETPI definesdemonstration project as a project under which thoseenvironmental technologies will be implemented whichoffer both technological solutions for pollution abatementand economic benefits for the industry. At the same time,the solutions should suit the local conditions for successfulimplementation."

ETPI is being implemented in alignment with the NationalConservation Strategy (NCS). It will be implemented in 20industrial sectors in two successive phases. Six priorityindustrial sectors including edible oil and ghee sector areincluded in the first phase.

This study focuses on environmental problems caused byedible oil industries and recommends measures to abatethem.

There are around 160 small and medium sized vegetable oiland ghee plants in Pakistan with a total capacity of overtwo million tons. Most of the mills have integratedfacilities of manufacturing soap as a by-product. The majorraw material used is raw oil extracted from different

botanical species. Pakistan imports 70-80% of the raw oil,

mostly from Malaysia. Water, electricity and natural gasare the major utilities consumed.

The main processes for cooking oil refining include:degumming, neutralisation, bleaching and deodorization.For ghee manufacturing, hydrogenation is also carried outin addition to these processes.

An edible oil industry generates large quantities ofwastewater. On average, for every ton of oil produced, thedischarge of wastewater is about 30 m3. The wastewater ofedible oil mills can be categorised into process wastewaterand non-process wastewater. Process wastewatercontributes to most of the pollution load in the effluent

being drained by the industry; while non-processwastewater constitutes the major portion of totalwastewater quantity. The process effluent is high in BOD,

COD, TSS, TDS, oil, phosphate, sulphate and chloride.Concentration of these pollutants in the process effluent ismuch higher than allowable NEQS limits. These pollutantsneed to be removed from the effluent to prevent the damage

being done to the environment, as well as to avoid payingthe Environmental Improvement Charges (EIC).

Spent fullers earth, spent nickel and filter cloth are themajor solid wastes of oil mills. Spent fullers earth andnickel are sold for down-stream use.

Spillage of oil on uncovered ground around oil storagetanks results in soil contamination, which can further leadto contamination of groundwater.

Major sources of air pollution are boiler and generatorexhausts, and emission from the gas cracking unit. From

these sources, carbon monoxide (CO) is emitted in veryhigh concentration. NOx emission is high in the generator

exhaust. CO and NOx have been suggested by Pakistan

Environmental Protection Agency (PEPA) for self-monitoring and reporting and emissions exceeding NEQSwill be liable for EIC. In some industries gas cracking unit

also emits huge amount of carbon dioxide which is agreenhouse gas.

In general, occupational health and safety (OH&S)situation is very poor in the edible oil mills. Use of any

protective gear by employees is almost non-existent.Inefficient and obsolete processes consume and wastemuch energy as compared to modern technologies.

The recommendations to improve environmentalperformance are categorised as in-house improvements,cleaner technologies, and end-of-pipe treatment. In-houseimprovements and cleaner technologies will not only result

in the improvement of economical and environmentalperformance of the mill, but will also reduce the cost of theend-of-pipe treatment.

Oil losses in the effluent can be reduced either byincreasing the size of the separation chambers beneath the

pre- and post- neutralisation vessels or by replacing gravitysettling by centrifuge separators. This measure will alsoreduce BOD and COD of the effluent. Water consumptionas well as discharge can be reduced significantly byreusing/recycling the cooling water and vacuum water after

proper treatment. End-of-pipe treatment options, whichinclude oil skimmers and biological treatment of the

process wastewater, are the ultimate solution forcompliance with the NEQS. The oil concentration in theeffluent can be reduced either by gravity settling or

chemically enhanced dissolved air floatation. Aeratedlagoons or activated sludge are the recommendedbiological treatment options to remove organic pollutants.

The solid waste management system can be improved bygood working practices. By applying solvent extraction, theoil content in spent earth can be reduced to 5%. Paving thearea near oil storage tanks and collecting spills will reducethe risk of soil contamination.

Air emissions can be reduced by optimising the combustionat boiler and recovering CO2 from the gas cracking plant.Installation of a stack on the gas cracking exhaust, use of

protective gears such as gloves, goggles, ear muffs, etc.,will improve the working conditions in the plants.

The wastage of energy can be minimised by efficiently

performing the processes, such as preheating of incomingoil with outgoing oil at hydrogenation and deodorization.The edible oil industry is an energy intensive industry andthe industrys normal working is effected because of powerfailure. The new concept of producing electric as well asheat energy together at the plant, known as Cogeneration,has been developed recently in developed countries. It is avery efficient and cost-effective way to generate electricityand heat for the industry.

To improve the overall environmental conditions of the

industry Environmental Management System (EMS)should be implemented. This is also a requirement of ISO

14000.


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1. Introduction

This report aims to address the environmental pollutionproblems of the Edible Oil sector. It has been compiled on

the basis of the findings of three environmental audits,conducted in three edible oil mills under the Environmental

Technology Program for Industry (ETPI). The objective of

this report is to assess the nature and extent ofenvironmental problems caused by an edible oil industryand to recommend solutions to mitigate their impacts. Thelimitation of this report is that the information has been

generalised on the basis of the data obtained from threeenvironmental audits for the whole sector. This limitation

has been minimised using substantial national andinternational secondary information available for the edible

oil sector.

1.1 Environmental Technology Program forIndustry (ETPI)

The Environmental Technology Program for Industry

(ETPI) is a joint project of the Federation of PakistanChambers of Commerce & Industry (FPPCI) and the

Government of The Netherlands. The primary objective ofETPI is to promote the use of environmentally safe

technologies for the production of environmental safeproducts by Pakistans manufacturing/industrial sector.

To provide the required technical expertise and support to

industries, a consortium of local and foreign consultingfirms has been hired to execute ETPI. The members of the

consortium are.

National Environmental Consulting (Pvt.). Ltd.(NEC), Pakistan; the lead consultant;

HASKONING, Royal Dutch Consulting, Engineeringand Architects, The Netherlands;

KRACHTWERKTUIGEN (KWT), The Netherlands;

Management for Development Foundation (MDF),The Netherlands; and

Hagler Bailly, Pakistan.

This five year project began in 1996 and works with

Pakistani industries and their associations in identifyingthose pollution prevention and abatement technologies

which are economically most feasible, and in implementingthese solutions. The five components of the program

include the development of a user-friendly database ofrelevant information, institutional networking within and

between key industrial institutions of the country,dissemination and communication to promote cleanerindustrial production, institutional support and training to

create in-house environmental capability within chambersand industrial associations and demonstration projects in 20

selected industrial sectors to demonstrate the economicfeasibility and environmental efficacy of environmental

technologies.

1.2 Demonstration Project

Each component of ETPI has been given specificdefinition, and carries its own objective, scope of work and

methodology. The present study is part of the

demonstration project component. Hence, this report willfocus mainly on this component.

As discussed above, physical interventions in the form of

demonstration projects are an integral part of ETPI, which

is defined as a project under which those environmentaltechnologies will be implemented which qualify both thetechnical and the financial feasibility criteria, and at the

same time are relevant to the local industrialists.

Improvements in processing practices will also be anessential part of the demonstration projects.

Objectives of the demonstration project include:

To establish live examples in the major industrialsectors of Pakistan for the direct dissemination of

environmental technologies in the country.

To prepare a representative database in the shape of anindustry specific Environmental Audit for establishingthe environmental policy implication, financial and

institutional support requirements. To create a more aware and committed constituency of

industrialists for undertaking environmental

investment.

To identify industry sector specific research anddevelopment areas in the discipline of environment

and industry for local and international researchinstitutions.

For the implementation of a demonstration project, a

comprehensive procedure for the selection of industries in

each sector has been developed. According to thisprocedure, three industries are selected for an

environmental audit from each sector. Subsequently one ofthese three is selected for the demonstration project.

1.3 Environmental Problems of Edible Oil Industry of Pakistan

The biggest problem faced by an edible oil industry iswastewater, both quantitatively and qualitatively.

Wastewater generation in an edible oil industry can bedivided into two categories:

Wastewater generated directly from processes e.g.neutralisation washings etc.

Wastewater generated from auxiliary systems e.g.cooling and vacuum systems etc.

Wastewater generated from both these sources variesgreatly in pollution load and concentration. Process

wastewater contains high amounts of BOD, COD, oil &grease, TSS, TDS, and nickel etc. Wastewater generated

from the auxiliary systems is huge in quantity andrelatively higher in temperature. It sometimes contains

traces of VOCs. Boiler condensate recovery system is notefficient in some, and practically non-existent in most.

Apart from liquid waste, solid waste and air emissions are

also generated. Solid waste generation is mainly in the formof spent earth, filter cloth, and spent catalyst. Spent earth

and spent catalyst are in slurry form and are combinedtogether to extract what is known as Carbon Oil before

their final disposal. After carbon oil extraction, the left overslurry is sold to contractors.


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Soil contamination can be seen around oil storage tanks in

oil mills due to spillage on uncovered ground. This alsoposes risk of contaminating the groundwater.

Air emissions are generated mainly from boiler and

generator stacks. Besides, process emissions may also bepresent, comprising of volatile organic substances from

bleaching, deodorization, etc. In some cases, air emissions

have pollutants higher than the limits mentioned in theNational Environmental Quality Standards (NEQS).

Noise and odour levels at many places in every mill arehigh. Temperature of the working areas is generally

acceptable during winter season, but it becomes quite highduring summer. General rating of the lighting andventilation arrangements is on a scale of satisfactory to

poor.

A variety of chemicals are used in edible oil processing.While other chemicals also contribute, use of nickel as

catalyst during the hydrogenation process is the mostimportant concern from an environmental point of view.

Chemicals used pose a twofold problem. Firstly, they comein the wastewater or as waste products of chemical

processes. Secondly, they might come into direct contactwith the persons handling them. Generally, practices for

handling of chemicals in oil mills are poor and need drasticimprovement. Open air storage and transportation, manual

feeding, and dripping of chemicals is common. In most ofthe mills, workers are improperly attired. Use of protective

gears is very rare, and most of the workers work withoutshirts.

Edible oil processing requires quite an intensive use of

energy. It is due to the fact that for different processes andoperations, different temperatures have to be maintained.

The most common modus operandi is to heat up watereither to steam, or to higher temperature, and then to

transfer the energy contained by this water to the material

being processed. Some amount of this energy is consumed

during the processes, while the remaining is lost eitherduring the cooling of the product for the subsequent

process, or in terms of heat contained by the wastewater. Inalmost all cases, an efficient arrangement of heat transfer to

save this energy does not exist.

Though some edible oil mills have acquired ISO 9000

certification and some are passing through theimplementation phase of ISO 9000 standards, others stilllag far behind. A lot more could be achieved from the

occupational health and safety (OH&S) perspective. Themanagement is keen to undertake environmental initiatives

in many cases. Still, the awareness level in workers and linestaff is dismally low, making the implementation of betterin-house management practices difficult. This, however,

does not liberate the management from the responsibilityand the resulting consequences.

Since it is perceived that environmental protection calls to a

large extent for investments with low or nil payback, it isnatural that most of the industries tend to postpone

environmental protection projects for as long as possible.This perception is not true in every situation, and often is a

misperception.

With the promulgation of the Pakistan EnvironmentalProtection Act 1997, the Pakistani edible oil industry will

be required to comply with the regulations forenvironmental protection. The Pakistan Environmental

Councils Environmental Standard Committee hasproposed certain Environmental Improvement Charges to

be imposed on the industries not complying with NEQS. Aformula for calculations of these charges has already been

devised. Therefore, every edible oil mill would have tothoroughly investigate its existing operations with the aim

of identifying opportunities for containing theenvironmental impacts through implementation of

appropriate in-plant measures.

2. The Edible Oil Industry

Pakistani society has traditionally been consuming butterfatDesi Ghee prepared from butter by heating, as a cookingmedium of choice. However, this product has been in shortsupply for a long time due to numerous reasons. Therefore,the past few decades have witnessed an increasingdependence on the vegetable oil, and products derived fromit. Until the mid-seventies, domestic production of edibleoils was sufficient to meet 75% of the domesticrequirements. A high rate of growth in vegetable oilconsumption afterwards due to population growth, increasein per capita income, and decrease in the real price ofvegetable ghee, created a gap between production and

demand. The share of imported oils and fats has thus beenincreasing gradually to fill up this gap.

Presently, the per capita consumption of vegetable oil/gheeis 16-18 kg per annum. The average demand growth is

projected at 4.4% per annum between 1988-2000, and thedomestic production is expected to increase by 7.3% duringthe same period.

Pakistans Edible Oil industry was nationalised in 1972 anda public sector organisation i.e. Ghee Corporation ofPakistan (GCP) was created to run this industry. Since1988, private sector has been allowed to emerge and grow.Most of the units under the control of GCP have been

privatised. At present 94% of the sector is under private

sector control. A total of around 160 small and mediumsized vegetable oil and ghee plants are operational with atotal capacity of over two million tons.

Two institutions in Pakistan represent the edible oilindustry. The Pakistan Vanaspati ManufacturingAssociation (PVMA) is an association of over 100 millswhich import refined crude oil, process and package it, andmarket it. The total installed capacity of these units isaround 1.8 million ton. The All Pakistan Solvent ExtractionAssociation (APSEA) is an association of five mills. Thesemills process oil from raw oil seed through solvent

extraction process. The total installed capacity of theseunits is around 550,000 tons.

2.1 Raw Material

The edible oil industry uses a variety of raw oils such asRBD soft and hard1, palmolein, soybean oil, corn oil,cottonseed oil, rapeseed oil, sunflower oil, and canola oil.The last five raw materials are used occasionally, either dueto the shortage of the soybean supply, or because ofspecific requirement of the product.

1

RBD soft oil is refined, bleached, and deodorized oil withno hydrogenation. RBD hard oil is refined, bleached anddeodorized oil with hydrogenation.


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The local production and imports for 1995 is shown in

Table 2.1. Cottonseed, corn oil, and canola (recently) arepurchased from the local market. The local oil seed

production caters to only 20-30% of the requirement,whereas the rest is imported. Palm oil, which has 80%

share in the imports of oil and fat, is being imported fromMalaysia, while sunflower and soybean are imported from

the Eastern European Block. In fact, by importing over a

million ton of palm oil, Pakistan has become worldslargest importer of palm oil from Malaysia.

Table 2.1: Local Production and Import ofEdible Oil (1995)

Quantity (Ton)S. # Type

Local Imported

1. Cottonseed Oil 374,400 14,000

2. Sunflower Oil 30,000 24,600

3. Rape Seed Oil 66,000 -

4. Butter Fat 379,900 -5. Soybean Oil - 200,000

6. Palm Oil - 1,059,0007. Palm Kernel Oil - 5,800

8. Tallow - 57,000

Total 850,300 1,360,400

Source: PORIM Karachi

Oils mainly consist of triglycerides, however, some

impurities such as gummy matter, pigments, and long chainfree fatty acids (FFA) are also present in them. These

unwanted substances are removed from the oil duringvarious refining processes.

2.2 Process Chemicals

Various chemicals are used at different stages of the

refining process. A list of these chemicals, and their

utilisation is shown in Table 2-2.

Table 2-2 : Process Chemicals and their Usage

Chemicals Usage

Phosphoric acid De-gumming

Caustic soda FFA removal, oil extractionfrom fullers earth and soap

manufacturingFullers earth Pre- and post-bleaching

Nickel sulphate Catalyst in hydrogenationCitric acid Odour Removal

Vitamins ( A, D &E) To improve nutritional value ofoil

Butyric acid & Ethylbutyrate

For flavouring the ghee

Antioxidant BHT For stability of the productSulphuric acid For acid oil production.

Common salt (NaCl) For soapstock graining and forthe regeneration of cation resin

Monoethanolamine(MEA)

To absorb CO2 in thepurification of H2 gas.

Source: ETPI primary & secondary surveys

2.3 Utilities

The consumption of different utilities in oil mills is

presented in Table 2-3.

Table 2.3: Utilities and their Consumption

Utility Quantity Usage

Water

(m3)

12 - 45 Washing of oil, cooling &vacuum systems, steam

production, etc.

Electricity(kwh) 45 130 Process house operations,vacuum pumps, waterpumps, natural gascracking unit, boiler house.

Natural Gas

(Mcf)

3 25 H2 gas manufacturing, soapmanufacturing, boilers, etc.

Steam (tons) 1.4 3.4 Process house, gas crackingunit, heating of oil instorage tanks, decanting.

Source: ETPI surveysNote: The quantities are based on 1 ton of oil or gheeproduced.

2.4 Process Description

The major process being carried out in the oil mills is the

refining of raw vegetable oil to render it edible.Hydrogenation is also carried out for ghee manufacturing.Apart from cooking oil and ghee, soap, acid oil, carbon oil,and bottled carbon dioxide are also produced as by-

products. The unwanted material, removed during the oilrefining process, is utilised either for soap or acid oilmanufacturing.

2.4.1 Vegetable Ghee

Vegetable ghee is produced by blending and processingdifferent raw oils. A detailed process flow sheet is shown inFigure 2.1.

De-GummingThe first step is the removal of gummy matter such as

phospholipids and lipoproteins etc. from raw soybean orcottonseed oil. It is accomplished by exposing the oil towater and adding the phosphoric acid at 50oC. As a result

precipitate of gum is generated which is removed from theoil.

Pre-NeutralisationPre-neutralisation process is done to remove FFA from rawoil. Caustic Soda solution proportionate to FFA is mixedwith oil. This results in the neutralisation of the FFA. Theresulting soapstock is allowed to settle and then drained outfrom the refining kettle. Three hot water washings aregiven to remove residual soap.

Pre-BleachingThe purpose of oil bleaching is to eliminate its colouring

pigments through the adsorption on bleaching earth.Fullers earth is used for bleaching because of its excellentadsorption power.

The bleached oil containing fullers earth is passed througha series of filter presses to remove the spent earth.

HydrogenationHydrogenation process is the hardening of oil to reduce itsun-saturation. At the same time, it improves the stability ofthe product against its oxidation. Chemically, the degree ofun-saturation decreases by passing hydrogen gas throughoil in the presence of nickel catalyst at 150oC.


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-

FILTER PRESS

Spent Ni

POST NEUTRALIZATIONINCLUDING WASHINGS

POST-BLEACHING

POST FILTER PRESSSpent Fullers

Earth

Ni Recycle

VacuumWastewater

Soap Stock Wasteater to Soaps Pits

HARDENING STORAGE

CO2, CO, NOx

Fresh Ni

HARD OIL TANK

RAW OIL MAIN STORAGE

DEGUMMING / PRE-NEUTRALIZER /

WASHING

Soap Stock &Wastewater to Soap Pits

PRE-BLEACHERVacuumWastewater

PRE-FILTER PRESS

NATURAL GASCRACKING UNIT

HYDROGENATION

H2

Spent Fullers

Earth

DEODORIZER

POLISH FILTER

SEAMING MACHINE

Vacuum WasteW ater

CHILLING SECTION

WARE HOUSE /DESPATCH

Phosporic Acid +Lye + Water

Spent earth + Oil +Filter cloth washing

Effluents

Fullers Earth


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Post-NeutralisationPost-Neutralisation is performed in the same way as pre-neutralisation, except that dilute lye is used because hardoil has a low FFA content at this stage.

Post-BleachingPost-bleaching is performed in the same way as pre-

bleaching.

DeodorizationMost of the odorous substances along with FFA, sterols,tocopherols, saturated and unsaturated hydrocarbons and

pesticides are stripped out by injecting dry steam into oil at235 245oC. Citric acid is also added to remove the odour.

After deodorization, the deodorised oil is cooled in the de-cooler to about 85oC. The remaining odorous substancesare removed during the de-cooling under vacuum.

After cooling the hard oil is passed through a final filterpress called Polish Filter, which removes undissolvedcitric acid, remaining particles of the fullers earth or nickelcatalyst, and any other fine impurities. It also reduces theintensity of the final colour of the oil/ghee.

FortificationBefore sending to the filling section, vitamin A+D, andvitamin E are added. Antioxidant BHT is also added forstability and for the taste of the product. Some flavours arealso added like butyric acid and ethyl butyrate, in a ratio of88:12.

The finished product after packaging is stored in a chillingroom at a temperature of 0oC for 8-12 hours. This processconverts the hard oil from the molten state into finegranules and improves its appearance. Afterwards it is sentto the warehouse.

2.4.2 Cooking Oil

Manufacturing of cooking oil is similar to gheemanufacturing except that hardening (hydrogenation) of the

cooking oil is not required. Therefore, hydrogenation, post-neutralisation, post-bleaching, and post-filtration are notperformed.

Generally, pure soybean oil (100%) is used in the cookingoil manufacturing. Cottonseed, canola, sunflower or cornoil are also occasionally used for this purpose. A processflow diagram is shown in Figure 2.2.

2.4.3 Acid Oil

Production of acid oil is mainly concerned with thedisposal and treatment of soapstock. Soapstock is generally

treated with excess alkali to enhance saponification of anyremaining neutral oil present in it. Later, it is boiled for 30-

45 minutes through steam coils fitted inside the vessel.Sulphuric acid is added which reacts with soapstock to

form acidulated soapstock or acid oil.

2.4.4 Carbon Oil

Carbon oil is extracted from the spent fullers earth through

the alkali reaction. Spent catalyst is also mixed with spentearth for carbon oil extraction. The spent earth collected

from both pre-and post-filter presses is sent to the soapsection. Caustic soda is added in it and the slurry is heated

through steam coils fitted inside the vessel.

Water is also added to facilitate the decanting of oil from thespent earth. Continuous stirring enhances the skimming of oil

at the upper surface of the slurry. After stirring, the decanted

oil floating above the surface of the slurry is skimmedmanually and is collected in a large drum. Most of this oil is

used in the preparation of soap. Fullers earth after carbon oilextraction is sold to contractor for final disposal.

2.4.5 Soap

Raw materials used in soap manufacturing are soapstock,

oil/ghee spills, soap foam collected from fat traps/soap-pits,and acid oil or carbon oil.

Caustic soda solution is added to a batch of raw material

and saponified by boiling with live steam. After fatstockhas been saponified, common salt is added to it and boiling

continues. At a certain stage of salt concentration, whensoap becomes insoluble boiling is stopped and the soap is

allowed to settle overnight. It settles to form four layers.

The uppermost layer is foam below this is neat soap, thethird layer is of dirty soap or nigre and at the bottom is

some spent lye.

After settling, foam is pushed aside and neat soap ispumped out and filled in frames for solidification.

3. Environmental Stresses and their Quantification

The edible oil industry is one of the many chemical process

industries, which contribute to environmental pollution. In

the following sections pollution from edible oil industriesthrough various sources have been discussed in detail.

3.1 Wastewater

Generation of large amounts of wastewater is the biggestenvironmental problem faced by the edible oil industries.

Wastewater is generated through various sources, varyinggreatly both in quantity and quality.

3.1.1 Sources and Disposal

The wastewater generation sources from an edible oil millcan be broadly divided into four categories:

Process wastewater

Cooling water

Vacuum water

Boiler and softening plant

Detail of these sources is given in the following section:

Process wastewaterFollowing processes contribute to process wastewater:

Neutralisation

Generation of wastewater from the pre-/post-

neutralization process is periodic. Wastewatercontaining soapstock is transferred into a separationchamber, with generally three compartments. Soapstock,


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Fi ure 2-2: Cookin Oil Process Flow Sheet

DECANTING UNITRAW OIL

MAIN STORAGE TANK

* DEGUMMING

NEUTRALIZATIONINCLUDING WASHING

BLEACHING

FILTER PRESS

DEODORIZER

COOLERS

SEAMING MACHINE

WARE HOUSE /DESPATCH

HOT OIL TANKS

DRYING

Waste Water & SoapStock to Soap Pits

Vacuum (wastewater)

Spent Fuller Earth

(to Soapry & Oil)

* Cotton Seed / Sunflower Oil

POLISH FILTER

Phosphoric Acid

Fullers Earth

Vacuum (Condensate)

Lye + H2O

Effluent

Good Oil

Vitamins + BHT(30 g. + 20 g.)


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oil, and water are separated in the successive

compartments. Wastewater goes to the fat trap after

separation of soap stock and water.

Acid Oil Production

Acid oil production is another source of wastewater.

Wastewater stemming from this source is small in

quantity but qualitatively it is significant.

During this process acidulated soapstock or acid oil

rises upward in the reaction vessel due to its low

density, while the acid water, containing remaining acid,sodium sulphate and water-soluble impurities, settles

down. The acid water is drained out to the fat trap from

where it is discharged into the sewer.

Soap Manufacturi ng

The brine water from the graining process during soap

manufacturing is drained out after settling. This wastewater

goes to the soap pit and after decanting oil and soap, it isdischarged into the sewer.

Fi lter Cloth WashingThe filter cloths, used in the filter press, are washed using

caustic soda, water, steam and detergents. The caustic bath,

which is very small in quantity, is retained and is drained

once every three months. Water bath is drained every

month and detergent washing is intermittent. All the above

three streams go into the final trap and after decanting oil,

wastewater is discharged into the sewer.

Cooling WaterWater is used for equipment/product cooling purposes inhydrogenation, deodorization, gas cracking unit andammonia compressors. The cooling water is recirculated

after dissipating its heat by spraying. The capacity of

spraying system is generally insufficient to dissipate

enough heat quickly, hence most of the water is drainedout.

Vacuum WaterWater is used in the vacuum system to provide vacuum forcertain operations. Vacuum water having relatively high

temperature (average 35oC) is cooled through spraying and

then is re-circulated. As the spraying system does not have

the required efficiency in most cases, a portion of water has

to be discharged to maintain the temperature to the desired

level.

Boiler and Softening PlantThe boiler generates wastewater as blowdown. Somewastewater is also generated during the regeneration of the

softening plant. The pattern of wastewater generation is

periodic, however it is distributed almost evenly over 24

hours.

DisposalEdible oil industries usually dispose off all their effluent

into nearby receiving water bodies, such as canal, river or

sea, without any treatment.

3.1.2 Quantification

The quantification of wastewater was done on the basis ofwater balance, flow monitoring, and water consumption.

Based on the information of audited mills, the typical

ranges of wastewater generation are tabulated in Table 3-1.

Table 3-1: Daily Wastewater Discharge

Source Wastewater Quantity

m3/100ton of oil/ghee

Processes 50 - 80

Auxiliary Systems 1400 - 3600

Total 1450 - 3680

Source: ETPI survey

3.1.3 Characterisation

Wastewater of an edible oil mill can be divided into two

separate classes i.e. process wastewater and non-process

wastewater. The process wastewater was found to be highly

polluted as compared to non-process wastewater. The

characteristics of process wastewater and non-process

wastewater are given in Table 3.2.

Table 3.2: Wastewater Analysis

Parameter

Process

Wastewater

Cooling &

Vacuum

Wastewater

pH 11 12 6 - 8

Temp (oC) 40 50 -

BOD5 450 700 -

COD 1300 2100 -

TSS 2000 16500 -

TDS 3000 20000 350 - 10000

Oil & Grease 100 180 0 - 5

Nickel 2 - 2.5 -

Phosphate 10 20 -

Sulfate 10000 - 15000 -

Chloride 1525 - 5300 -

Conductivity 30 - 1400 -

Total Alkalinity 6000 - 22200 -

Source: ETPI survey, 1998Note: All values are in mg/l, except pH, Temp. (

oC) &

conductivity (ms/cm).

3.1.4 Pollution Load

The pollution load generated daily by edible oil mills is

presented in Table 3-3. This has been calculated by

multiplying quantity of wastewater with the concentration of

each parameter.

Table 3-3: Daily Pollution Load

Pollution Load

Parameters Mill-1 Mill-2 Mill-3

BOD5 60 230 1,600

COD 170 380 3,000TSS 280 130 3,100

TDS 3,750 960 5,400

O&G 15 0.8 15

Ni 0.05 0.5 0.5

PO4--- 4.2 -- --

SO4 200 -- --

Cl- 304 1,530 95,000

Total Alkalinity 1,150 1,000 1,800

Source: ETPI survey

Note: All quantities are in Kg per 100 tons of oil/ghee


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3.2 Solid Waste

Solid waste generated by edible oil mills can be classified in the

following general families:

- General waste

- Tin scrap

- Filter cloth

- Sludge from settling ponds, fat traps and raw oil tanks

- Spent earth

- Spent catalyst

- Spent lubricants

General type of waste produced usually contains pipes, mild

steel (MS) sheets, iron angles, wires, cans, bottles, and waste

paper. Some of this solid waste is sold to a contractor on

monthly basis, while the remaining is disposed off at municipal

garbage dumps.

Tin scrap consists of rejected tin containers, lids and waste from

tin can manufacturing area. Tin waste is temporarily stored

inside the mill and afterwards is sold for recycling. The quantity

of scrap is estimated to be 2-10% of the total tin used.

Filter cloth is used in the filter press. Once the filter cloth is

fixed in a filter press, it could serve for 4-6 batches after which,

the filter press is dismantled and filter cloths are washed. One

piece is used twice or thrice before it is discarded. After

rejection, filter cloths are used for floor cleaning and general

cleaning purpose.

When water ponds are cleaned the sludge is produced. The

quantity is dependent on the quality of water stored. Sludge is

also produced in the fat trap, where the oily wastewater from

pre- and post- neutralisation is stored. This sludge is used for

soap manufacturing. Wastewater from the filter cloth washing,

acid oil production, soapstock tanks and soap manufacturing

goes to another fat trap. The sludge from this trap is also used to

make soap.

Raw oil tanks are emptied twice a year for cleaning purposes.Raw oil storage tank also produces sludge. The sludge that is

settled at the bottom is salted and heated. The upper layer of oil

is skimmed to be used in the process. The rest is sent to the soapsection for soap production.

Fullers earth is used in the pre-and post-bleaching process. Oil

content of spent Fuller's earth after filtration of the oil coming

from bleaching is about 40% by weight. This earth is scraped

from the filter clothes and processed to extract carbon oil.

Afterwards, it is sold to outside vendors. The cleaning is done

manually and needs considerable labour force, as spent earth is

put into used fullers earth bags and taken out of the building by

workers.

Nickel (Ni) is used in hydrogenation process as a catalyst. The

general practice is to recycle some of the used nickel and to add

fresh catalyst for the total required quantity. The ratio of

recycling to fresh varies from mill to mill. After about 5 batches,

the spent Ni is completely replaced by fresh Ni. Spent Ni ismixed with spent earth and treated for carbon oil extraction.

Afterwards it is disposed off, generally with spent earth.

Spent lubricants come from the machinery and equipment

maintenance. These are sold for reuse or for burning in cement

kilns or brick furnaces. The details of solid waste generated by

edible oil mills, with its per annum quantities, are tabulated in

Table 3-4.

Table 3-4: Details of Solid Waste

S. No. Category Type/Source Quantity Fate

1 General Pipes, MS sheets, iron angles,wires, cans, broken glass,

bottles, paper, plastic, etc.

Sold or disposed off

2. Tin Scrap Tin workshop Sold for recycling3. Filter Cloth Filter press 0.1 - 0.2 m Mostly used for cleaning etc.

Finally thrown with garbage

4. Sludge From water pondsFrom small fat trapFrom big fat trap

From raw oil storage tanks

Disposed off at solid waste disposal sitesUsed for soap makingUsed for soap makingUsed for soap making

5. Spent FullersEarth

Pre-bleaching, post-bleaching,

carbon oil making6 - 9 kg Sold after Carbon oil extraction

6. Spent Nickel Hydrogenation 20 - 160 g Mixed with spent fullers earth and carbon oilis extracted from the mixture. Afterwards, thespent mixture is sold to contractors for down

stream uses

7. Spent Lubricants From machinery Sold to contractors for burning in kilns orfurnaces.

Source: ETPI Survey

Note: Quantities of wastes are based on per ton of oil/ghee produced.

3.3 Soil Contamination

Soil contamination in an edible oil industry is due to oil

spillage. Oil spillage on soil can be found, in the following

areas:

Underground furnace oil deposit: Uncovered soil near

underground furnace oil deposit gets highly polluted

with furnace oil spillage.

Raw oil tanks: Uncovered soil near raw oil tanks gets

highly polluted with raw oil spillage.

Carbon oil manufacturing area: Bags containing spentearth are stored on unprotected soil and in the open air.

This means that polluted rainwater and leachates from

this area go into the soil.


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3.4 Air Emissions

In general, vegetable oil refining processes does not have

significant air emissions. In the refining process, materialsare volatilised, but in every case the volatilised material is

condensed either for recovery or to maintain low pressuresin the systems.

Vents from storage tanks of raw oil and products that havea certain vapour pressure can be a source of vapours. This

emission occurs principally on the filling of the tanks.

However, the vapour pressure of vegetable fats and oils issuch that the contribution is not significant.

Air emissions emitted by an edible oil mill come chiefly

from the auxiliary systems, i.e. boiler, gas cracking plant,and power generator etc. Samples from these sources were

analysed. The results of these analyses are presented in

Table 3-5.

Table 3-5: Air Emission from Different Sources

S. No. Emission Boiler Generator Gas Cracking

Plant

NEQS

1. CO, mg / Nm3 40-130 2060 3000 800

2. CO2, VOL % 2 205 0.8 18 -

3. NOx, mg/Nm3 60-125 1300 -- 400

4. SO2, mg/Nm3 -- 110 -- 400

5. Smoke, Ringlemann Scale -- 5 -- 2

6. Particulate Matter, mg/Nm3

-- 275 -- 300Source: ETPI survey

3.5 Noise Emissions

Industrial equipment and machinery create high noise levels

during operation. The main noise sources in edible oilindustry include:

Steam ejectors at the roof of main process building

Tin can manufacturing

Gas cracking plant

Boiler

Hydrogen compressor

Ammonia compressor

The noise levels in the above mentioned areas are quite high,

although they were not measured. The allowable noise levelunder NEQS is 80 dB.

3.6 Occupation Health and Safety (OH&S)

In edible oil mills OH&S hazards are due to the following

reasons:

Improper handling of chemicals.

Poor ventilation

Slippery floors

High noise levels

The use of protective gears in handling of chemicals is non-

existent. Workers were found bare handed working with

chemicals such as caustic soda.

Because of poor ventilation in the process area, fumes

emitted from different processes stay inside for longer time.

Floors get slippery because of oil spills in refining area.

Also industry uses detergent to wash the floor after every

shift, which makes the floor even more slippery.

3.7 Energy Inefficiency

Refining of edible oil includes a number of heating and

cooling operations where the transfer of thermal energy takes

place. This transfer of energy is not efficient in most of theedible oil mills of Pakistan. Wastage of energy is due tofollowing reasons in oil mills:

Cooling of oil after hydrogenation and deodorization.

Improper insulation of steam pipes.

Prolonged deodorization at low temperature.

Steam distributing pipes without proper insulation results indecrease of steam temperature hence more steam is required.

In some industries deodorization of edible oil is carried out

at 190oC for a period of 1.5 hours. However, in theliterature it is reported that the process is carried out at 235-

245oC, which is accomplished only in 25 minutes. The low

temperature deodorization, not only reduces the productionrate, but also increases the oil losses in terms of

polymerisation.

4. Impacts

The major adverse impacts of environmental pollution

caused by the edible oil mills are discussed in this chapter.

These impacts have been described with respect to the local

and global environment, workers health & safety and

deviation from the NEQS.

4.1 Impacts Associated with Wastewater

Pollution of water is the most important environmental impact

of edible oil mills. Impacts of wastewater generated from

edible oil mills are evaluated while keeping in mind the


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final destination of wastewater. Adverse effects of

pollutants on the ecosystem as well as on the surrounding

population are also taken into account. These impacts are

discussed pollutant wise in the following sections.

pH

Most of the processes discharge highly alkaline (pH >10)wastewater but some processes such as acid oil production

discharge highly acidic effluent. Aquatic life is severely

effected by the pH of the water and a larger deviation from

neutral pH could alter the natural biological activities. Also,

acidic or basic wastewater does not facilitate the bio-

degradation of organic pollutants. Wastewater with a high

pH value is also corrosive to the sewer system of the area.

Organic Pollutants

The COD value is the amount of oxygen required todegrade the pollutants present in the wastewater through

chemical degradation. COD indicates the chemically

degradable pollutants. Similarly BOD indicates the

biodegradable organic pollutants. BOD and COD cause the

depletion of dissolved oxygen in the water body.

Deficiency of oxygen in receiving water could causeadverse effects on biological activity in the water

environment. In the worst case this can result in the total

depletion of oxygen in the receiving water, causing an

anaerobic environment. This would be fatal to aerobic life

and would also create odour problems.

High COD/BOD ratio indicates the persistence ofchemicals present in effluent. Persistent chemicals always

pose risk of entering into the food chain.

Phosphates

Phosphorus is an essential nutrient for algae and otherbiological organisms. A high concentration of phosphates,

if discharged into the surface water, can result in the

growth of undesired aquatic life such as algae. This can

lead to the eutrofication of the receiving water body. Inmost of the countries, the phosphate concentration

allowable for discharge in water bodies is less than 1ppm

because of these characteristics.

Presently NEQS do not have any limit for phosphate in

wastewater but it is likely that phosphate limits will be

imposed in near future.

Sulphates

Under anaerobic conditions sulphate is reduced to sulphideand can form hydrogen sulphide. H2S is highly malodorous

gas and toxic at high concentration. Offensive odour can

cause poor appetite for food, impaired respiration, nausea,

vomiting and mental perturbation. Also, H2S can be

oxidised biologically to sulphuric acid which is corrosive todrain pipes.

Chlorides

Chloride concentration in wastewater is not significantlyreduced by conventional wastewater treatment methods,

hence finds its way into the receiving water. High

concentration of chloride in the water may convert the

agricultural land into saline land and unfit for agriculture if

the receiving water is used for irrigation purpose.

Particulate and Sediments

Suspended solids present in process wastewater arepartially organic in nature. Upon settling in the bottom of

the water body, they decompose aerobically as well as

anaerobically, depending on the prevailing condition. In

aerobic decomposition, dissolved oxygen of the water body

is consumed, creating a potential for adverse effects on the

ecological system of the water environment. Anaerobic

decomposition of organic compounds will generate odour.

Suspended solids also reduce the aesthetic value of the

receiving water body.

Total Dissolved Solids (TDS)

Process effluent from the edible oil mills also containslarge quantities of TDS. Most of the dissolved solids are

undesirable in the receiving water. Dissolved minerals and

organic constituents may produce aesthetically displeasing

colour, tastes and odour. Some chemicals may be toxic and

some of the dissolved organic constituents are known to be

carcinogens. Quite often two or more dissolved substances

combine to form a compound whose characteristics are

more objectionable than those of the original matter.

Oil and Grease

The concentration of oil and grease in process effluent ismany times higher than allowable limits of NEQS. High

amount of oil present in the wastewater may reduceabsorption of oxygen by the receiving water body, hence

resulting in the depletion of dissolved oxygen. This may

endanger aquatic life as discussed earlier.

Also, oil films on the surface of water result in reduction of

light transmission through surface water, thereby reducing

photosynthesis by aquatic plants. Oils may also form

suspension or emulsion in the water, which could be

harmful for fish and other aquatic life.

Nickel

Nickel is a heavy metal and is used as a catalyst in the

hydrogenation process of ghee manufacturing. Some of the

nickel is discharged into the effluent while most of the

spent nickel is disposed off as solid waste. Nickel is anessential element in animal nutrition in trace quantities but

toxic and carcinogenic in higher concentration.

4.2 Impacts Associated with Solid Waste

Dumping of rubbish and waste inside the plant causes

unhygienic conditions.

The sludge that is formed at the water ponds decreases the

ponds capacity, its recycling capability, and the quality of

water.

Having large amounts of sludge in the fat traps affect the

treatment capacity, as the water flows from one basin to the

next underneath the concrete baffles.

Burning spent nickel in kilns may result in the emission of

nickel compounds in the air. As nickel dust is a possible

carcinogen, producing respiratory cancer, hence its entry

into the air can pose a problem to the population living near

the kilns.

Burning spent oil and lubricants without any control about

the composition of the oil and the flue gases from

combustion is a source of air pollution.


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4.3 Impacts Associated with SoilContamination

Soil contamination can cause ground water pollution that

may afterwards affect surface water.Soil contamination nowadays is an important issue in

industrialised countries, and companies are very concernedabout its grave environmental impacts. In the past,

industries did not take into account the importance of soilcontamination, but this has drastically changed in the last

few years, as the price of land can decrease, or evenbecome nil, when the soil where the industry is located is

polluted.

4.4 Impacts Associated with Air Emissions

Impacts associated with possible air emissions from edibleoil industries are given in the following sections.

Oxides of NitrogenOxides of Nitrogen are emitted from boiler stack and thegenerator exhaust.

Continuous or intermittent exposure of humans to NOxmay cause certain illnesses, such as irritation in the

respiratory tract and abnormal accumulation of fluid in thelungs leading to pulmonary edema. Direct exposure of NOxto soil causes necrosis, causing vegetation loss and may

lead to inhibition of plant growth.

NOx undergo various photochemical and chemicalreactions in the atmosphere leading to the formation of

photochemical smog and acid rain. Although, emissions ofNOx from generator are for short period of time, still the

cumulative effects of NOx at global scenario should not beignored. Depletion of ozone at stratosphere level, formation

of photochemical smog and acid rain may occur due to this.

Oxides of SulphurOxides of Sulphur are emitted in oil mills due to the

burning of fuels in the generator, and also from gas

cracking. Direct exposure to these oxides can be veryharmful to human health, plants and vegetation. Theharmful effects are dependent on the concentration andexposure duration. Indirectly SOx reacts in the atmosphere

to form photochemical smog and acid rain.

Carbon MonoxideCarbon monoxide is a colourless non-irritating gas, whichis generated due to incomplete combustion.

At high concentrations exceeding 5000 ppm with an

exposure of few minutes, this gas can be fatal for human oranimal lives, by reacting with haemoglobin to form

carboxyheamoglobin.At much lesser concentrations, buut with a high duration ofexposure, this gas may still be dangerous for human beings,

as it may cause damages to visual perception, manualdexterity and the ability to learn.

Concentration of CO from the methane cracking plants andthe generator exhausts of the audited mills are very high.

Therefore its long-term impacts can not be ignored.

Particulate Matter (PM)Particulate matter covers a large variety of particles,varying in size and chemical composition, however in this

report, the fine particles of carbon from burning fuel are

considered.

Adverse effects of the particulate matter on human healthare reported in relation to the diseases of the respiratory

system. Lowering of the aesthetics value of a place and lossof general visibility may also be attributed to PM at high

concentration.

The general corrosion reactions on building materials, dueto the presence of NOx and SOx in the air, may also get

catalysed due to the presence of particulate matter.

Carbon Dioxide (CO2)Carbon dioxide is generated in large quantities duringnatural gas cracking in edible oil mills. In some mills this is

collected and sold to beverage industry. While in others thisgas is exhausted into the atmosphere. Laboratory results of

gas cracking plant exhaust show that the concentration ofCO2 in the exhaust is about 500 times of its concentration

in clean air.

CO2 is a green house gas and its higher concentration in theatmosphere is responsible for the phenomenon of global

warming.

4.5 Impacts Associated with Noise

Noise is considered as an interference to and impositionupon comfort, health and the quality of life. Given the

conditions like exposure limit and time, noise may haveboth physiological as well as psychological effects on

human health.

Physiological effects include dizziness, nausea, unusual

blood pressure variation, physical fatigue, loss of hearing,etc. While reduced mental capability and irritations may

attribute to psychological effects.

Very high noise levels were observed in the surrounding ofthe generator room and the boiler house. As these

operations require almost full attention from the workers allthe time, therefore each worker is expected to be exposed

to high noise for at least 8 hours in 24 hours. This conditionmay lead to a permanent hearing loss for workers as well as

physical and mental fatigue, which consequently may lowertheir manual and mental dexterity.

4.6 Implications Associated with Occupational Health and Safety (OH&S)

In edible oil refineries major issues related to OH&S are

handling of chemicals, improper ventilation in process

building, slippery floors and exposure to high noise.

Workers in Pakistan are habitually prone to work with barehands and feet. This puts them at the high risk of

contracting skin disease, such as chemical burns, irritations,

ulcers, etc. Handling of hazardous chemicals such as

caustic soda, sulphuric acids, nickel oxides, etc. without

protective gears poses serious health as well as safetyhazard.

In some industries fumes and exhaust gases emitted from

different processes stay in the process building because of

improper ventilation These cause discomfort to workersand also reduces their output. Some processes also emit

VOCs which may be carcinogenic.


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Slippery floor of the process building due to oil spills onthe floor, always poses risks of injuries to employees.

4.7 Impacts Associated with Energy Wastage

Environment is nowadays understood as a wide andcomprehensive field that includes not only avoidance of

pollution, but also efficient use of energy and natural

resources. Inefficient usage of energy has the following

disadvantages:

Wastage of money, as more natural gas or electricity isconsumed.

Wastage of non-renewable natural resources, as the fuelsrequired to produce the energy are limited natural

resources.

Higher emissions of air pollutants such as carbon dioxides,

as more natural gas and fuel are burnt.

5. Recommendations

A number of recommendations, aimed at the improvement of

environmental conditions of edible oil industries, have beenformulated on the basis of the findings of the three audits by

ETPI, and information available through various secondarysources. Each recommendation has been developed and

worked out on the basis of the present state of information.For further development and cost estimation of each

recommendation, more specific data would be necessary. Thiscan be undertaken at the implementation stage.

5.1 Wastewater Reduction & TreatmentIn the following sections, the detailed description for the

relevant recommendations formulated for wastewaterreduction and treatment is given.

5.1.1 Size Optimisation of Separation Chambers

Due to the small size of separation chambers beneath the pre-and post neutralisation vessels, a proper retention time is not

being given to the washing effluent containing the soapstockand oil etc. This results in incomplete separation of soapstock,

oil, and wastewater. It is recommended that the size of thesechambers be optimised. This would give the following

advantages:

Oil losses would be minimised and the recovery of goodoil would be enhanced at this stage, leading to economic

benefits.

The pollution load in the outgoing water would beminimised, leading to size optimisation of the end-of-

pipe treatment.

5.1.2 Recycling of Washing Water after NeutralisationUsually six to seven washes of about 1 m3 each are applied

after pre-neutralisation and four washes of 1 m3 each afterpost-neutralisation to remove soapstock from oil.

The pollution load transferred to washing water decreasesfrom the first wash to the last wash. Therefore, it seemsfeasible to reuse the water coming from the last wash in the

first wash of the oil. In this sense, it is recommended to makesome trials to check the possibility of using a counter current

washing scheme after post-neutralisation. If the resultsachieved in post-neutralisation are encouraging enough, thesame trial could be made for pre-neutralisation. Countercurrent washing is a normal practice in many industrial

processes.

The importance of decreasing the amount of water used for

washing after neutralisation is not based on the intake watersavings, but on the reduction of the wastewater treatment

plant size. Since pre- and post-neutralisation are the two

main sources of process wastewater and a future treatment

plant would be meant mainly for treating process water, areduction on pre- and post-neutralisation wastewater means

a reduction in the investment and operational cost of such aplant.

5.1.3 Replacement of Gravity Settling by Centrifuge after NeutralisationSoapstock and washing water are separated from the oil, after

pre- and post-neutralisation, by means of gravity settling.

The separation of soapstock and water from oil can be

improved by means of centrifugal separators, in whichcentrifugal force is applied to separate fractions as it forces the

heavier particles towards the periphery, while the light phaseflows toward the centre of the separator.

The separation efficiency of centrifugal separators is much

higher than of gravity settling. This results in the followingpositive effects:

Reduction in oil l ossesBecause of better separation caused by the centrifugal force,less oil is lost with soapstock and washing water. It has been

reported that the use of centrifugal separators instead ofgravity settling can reduce the loss of oil during

neutralisation to more than 25%.

Reduction of washing waterWhen centrifugal separators are used, only 2 washes (with anamount of water of about 10% of the oil weight each) are

required. According to the information received fromequipment supplier, normal process water consumption when

using centrifugal separator is about 50% of presentconsumption. Also it will mean a reduction in the investment

and operational cost of the treatment plant.

Reduction of water content in oi lThe use of centrifugal separators will also reduce the amountof water that remains in the oil after neutralisation by 50%. As

this water must be evaporated before bleaching, the decreaseof water content of the oil will mean a reduction in the amount

of steam required and the time used for this purpose.

Improvement of oil quali ty:Another benefit of using centrifugal separators is theimprovement of the oil quality after neutralisation. The

following oil quality can be achieved after neutralisation ifcentrifugation is applied:

Switching from gravity settling to centrifugal separation

means a drastic change in the neutralisation process. It is notpossible to carry out this step by means of some new

equipment and some small modifications to the present


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process. First of all, it means a change from batch process to

continuous process. Secondly, a complete new installationhas to be purchased and installed.

Table 5.1: Oil Quality due to Centrifugation

Characteristics Incoming Oil Product

Max. FFA content 5 % 0.05%Max. Phosphatide content 200 ppm 5 ppmMax. soap content 100 ppm

Max. impurities content 0.1%Max. moisture content 0.5% 0.5 %

Source: Equipment suppliers

The investment cost of a new refining plant of 187 ton/day

capacity is estimated at Rs. 33,000,000.

Annual savings achievable due to process improvement can

be summarised as follows:

Decrease of oil losses: approx. Rs 4,100,000/year

Steam savings at bleaching: approx. Rs 160,000/year

Personnel cost savings: a modern continuous refiningprocess is fully automatic and needs minimum of

personnel attention. One worker, with a part-time job,can operate this installation (including necessary

cleaning and maintenance works).

Savings in chemicals: with high efficiency equipment(mixers, reactors, separators), reactive and chemicals

consumption is reduced when implementing a continuoscentrifugal separation system.

Increase in energy consumption: centrifugal separatorshave high electricity consumption. Thus, theimplementation of centrifugal separators will mean an

increase in the electricity demand of the mill. Aninstallation as described above, has a typical electricity

demand of 12 kWh per ton of oil.

Comparing the investment cost with estimated annualsavings, the payback period of implementing a centrifugalseparation system can be estimated to be about 5 years.

5.1.4 Use of Pressurised Water for Floor Cleaning

It is recommended to use hoses with automatic shut down and

pressurised water nozzles (water flow stops automaticallywhen the hose is left on the floor) to clean the floor, in order

to increase the efficiency of washing and save the water.

5.1.5 Improvement of Foam and Soap Removalfrom Fat Traps

Soap and foam is removed from the fat traps manually afterclosing the outlet of the last fat trap and raising the water

level. As outlet of the last fat trap is closed, the water rises andoverflows from the last trap to the drain. The skimming soap

and foam is, therefore, discharged in the drain.

It is rather simple to provide the fat trap with a mechanical ormanual system that can take out the fat from the traps without

the need of raising the water level. The simplest form is a pipeof about 6 diameter positioned across the water surface and

mounted at the ends in slip bearing. The pipe has a slot cut init lengthwise. The pipe is equipped with a means of rotatingand sliding arrangements so that the slot may be positioned atthe desired elevation and the pipe can be moved along the

chamber. The slot is left at the top normally. When it is

desired to skim fat, the pipe is turned until the slot is belowthe fat surface. The oil flows into the pipe to a sump at the

end.

The investment required is very low (about Rs.25,000) anddaily operation will benefit as well as the environment. Such

fat removers may be even fabricated locally at the industrys

own workshop.

5.1.6 Reorganisation of Water Systems

Total water consumption can be minimised by means ofreorganising the water scheme. This reorganisation consists

mainly in segregating the water according to its use and pre-treating, recirculating and finally treating/discharging each

separately. Though, there is a certain segregation of water inindustry, it could be improved, as some of the water types are

mixed up. This would result in a decrease in waterconsumption hence in a smaller size wastewater treatment

facility.

Recommendations on how to maintain the quality of each

type of water with the aim of keeping the cycles as close aspossible and with minimum addition of fresh water are

given below:

a) Process water :

The food industry is generally subjected to strict

requirements regarding quality of water that is in contactwith the product. In the previous sections, recommendations

to reuse and reduce the consumption of process water havealready been outlined. The final treatment for process water

is discussed in section 5.1.8.

b) Cooling and vacuum water:

Presently, edible oil mills either discharge the cooling water

into the drain or recirculate it in the vacuum system. It isrecommended to establish two separate semi-closed systems,

for cooling and vacuum water, providing both of them withcooling towers to dissipate heat. By maintaining proper water

quality it is possible to operate the cooling and vacuumsystems in a closed loop, requiring low make-up water

addition and decreasing the water consumption considerably.

For the vacuum water system an indirect cooling system is

recommended. Vacuum water should be cooled in a heatexchanger with cooling tower water before being recycled to

the vacuum system. Thus, there is no direct contact betweenthe two water systems, and the problem of odour and/or

presence of any organic compounds is avoided. The heatexchanger will need some cleaning, therefore it is advisable

to have two heat exchangers, one in operation while the otheris on stand-by.

For long lasting and smooth operation and efficiency of thecooling system it is necessary to avoid corrosion, scaleformation and micro-organism and bacteria development.

These problems are normally avoided by means of usingwater of an appropriate quality, applying some treatment

(such as filtration) and by dosing some additives.

Because of evaporation, there is an increase of salt content in

water, which results in the scale formation. This is normallymitigated with a continuous blowing down of certain amount

of water, which is replaced by fresh water.


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c) Recovery of steam condensate at boiler:Presently, edible oil industries recover only about 15-50% ofthe steam as condensate. The rest is drained as water or sentto the air at deodoriser.

Following are the advantages of recirculating the condensate:

Energy savings, as temperature of condensate is higherthan the intake water

Less water consumption Less cleaning cycles of the ion exchange resins Less chemicals consumption

With a good piping system, 80% recirculation rate ofcondensate is possible. A good piping system means highquality materials at heat exchangers and a good preventivemaintenance program (to avoid leakage and contamination ofwater with oil). 80% recovery of condensate means waterconsumption in the boiler will be less than half of presentconsumption.

Besides, much attention must be put on boiler water quality,as it influences directly the life, performance andmaintenance requirements of the boiler. Problems ofcorrosion and scale formation are also present in boiler waterwith even more influence on the system life. It is of high

importance to remove oxygen and CO2 from condensate inorder to avoid corrosion. This is normally done by injectingsteam at the degasifier and by dosing some additives.

5.1.7 Use of Flow Meters

Presently, none of the measuring system or device is in use inthe process and water systems. The use of flow meters tomeasure the quantities of various material and water streamscould prevent the unnecessary excessive dosing, therebysaving the resources.

5.1.8 Wastewater Treatment

After all in-process recommendations have been undertaken,the only way to improve the quality of the wastewaterdischarge is by means of an end-of-pipe treatment.

Knowing the potential and limitations of in-houseimprovements and cleaner technologies, ETPI has adopted anapproach based on both types (in-house and end-of-pipe) ofenvironmental solutions. The approach is two-phased. In thefirst phase, cleaner production technologies (CP) will beimplemented. Once the industrial unit has stabilised the

pollution and hydraulic loads, then end-of-pipe (EOP)treatment facilities will be designed and will be implementedin the second phase. It is anticipated that by adopting thisstrategy two benefits will be secured. These are: (a) duringimplementation of CP the understanding of the managementand technical teams about the environmental problems andsolutions will improve, and (b) the EOP environmentalsolutions will be much smaller and more cost effective.

In case of edible oil industries, end of pipe treatment will bedifferent for process wastewater and non-process wastewater.

Process Wastewater Treatment

Although process wastewater is small in quantity ascompared to non-process wastewater, but it is highly

polluted with oil and has high BOD, COD and suspendedsolid. After segregation, the estimated quantity of thisstream will be in the range of 500-800 litre/ton of

production. The average values of pollutants in processwater will be:

BOD 600 mg/LTSS 2400 mg/LOil 100 mg/L

The treatment will comprise of two main steps i.e. primary

treatment and secondary treatment.

Primary Treatment

The purpose of primary treatment is to remove the floatable

oil and grease and suspended solids. This will also reducethe BOD and COD concentration. This can be achieved

either by gravity settling or by dissolved air flotation. Both

options are discussed below, and the pertinent design dataand costs are given in Table 5-2 and Table 5.3:

Table 5.2: Design Data of Primary TreatmentSystem

Parameter

Gravity

Settling

Tank

Chemically

Enhanced

DAF

Units

Flow 100 100 m3/day

No of Tanks 1 1 No.Surface area 4 0.75 m2

Depth 2.5 1 mChemical

Mixing Tank

- 1 No.

Depth - 1 mArea - 0.5 m2

Capacity of airpump

- 1.5 bars

Removal EfficienciesBOD 35 35 %

TSS 65 65 %Oil up to 50 up to 30 ppm

Table 5.3: Cost Estimates for PrimaryTreatment System

Cost In Rs.Components

Option 1 Option 2

Screen 70,000 70,000Civil work 60,000 40,000

Piping, mechanical & electricalequipment

150,000 250,000

Contingencies @ 15 % 42,000 54,000

Total 322,000 414,000

Operational and maintenance

per annum

70,000 150,000

Option 1: Gravity Settling:The principle behind this process is the same as used by theindustry to separate water, oil and soapstock in soap pits.The objective of gravity sedimentation or flotation is toachieve a slow, smooth, tranquil and uniform passage ofthe liquid stream from the inlet end to effluent end. Duringthis process the oil particles rise to the surface because oflower density and are removed by skimming them from thetop. Suspended solids will settle at the bottom of the tankand will be removed in the form of sludge. The details withschematic diagram are shown in Figure 5.1. Option 2: Chemically Enhanced Dissolved Air

Flotation

In this process air is dissolved in the wastewater under apressure of several atmospheres. When the solution isdepressurised, the dissolved air is released as fine bubbles.Additives such as aluminium and ferric salts are used to

bind the oil droplets together and in doing so, create astructure (floc) that can easily entrap air bubbles. A few air

bubbles on a floc will rapidly buoy it to the surface.


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In principle DAF resembles gravity settling but the surfaceoverflow rates are four times or even more, as the rise rateof particles is greater with attached air bubbles. Also the oilremoval efficiency is very high in case of chemicallyenhanced air flotation. The details with schematic diagramare shown in Figure 5.2.

Secondary TreatmentThe remaining oil in wastewater after gravity settling or

dissolved air flotation is in a dispersed state or in solution.Removal of the dispersed oil and other biodegradableorganic compounds can be accomplished by biologicaltreatment such as activated sludge process or aeratedlagoons.

Both processes require high capital investment. Aeratedlagoons require a large area of land but operational costsare much lower than activated sludge.

Option 1 Aerated LagoonsAn aerated lagoon is a basin in which wastewater is

biologically treated on a flow-through basis. A largesurface area is required because of high retention time.Oxygen is supplied by means of surface aerators. In anaerobic lagoon most of the solids are maintained insuspension by mixing while some of the solids settle at the

bottom and decompose anaerobically. The soluble products

of the anaerobic decomposition would, in turn, oxidise inthe upper layer of the lagoon. If groundwater pollution isnot an issue than this method will be low-cost because ofmainly earthwork construction.

Option 2 Activated SludgeThe activated sludge process is an aerobic, biologicaloxidation process in which wastewater is aerated in the

presence of a flocculent, mixed microbial culture, known asactivated sludge.

Essential elements in this process are: the aeration tank inwhich the activated sludge and incoming wastewater arethoroughly mixed (the mixture is known as mixed liquor)and an abundant supply of dissolved oxygen is provided; afinal settling tank for separating the activated sludge fromthe treated effluent; a return sludge system to recycle thesettled activated sludge solids back to the influent; and a

sludge digester.

Operationally, biological waste treatment with the activatedsludge is typically accomplished using a flow diagram suchas that shown in Figure 5.3.

Table 5.4: Design Data of Secondary TreatmentSystem

Parameter Option 1 Option 2 UnitsFlow 100 100 m3/day

Aeration Tanks/LagoonsNo ofTanks/Lagoons

2 1 No.

Surface area 120 20 m2

Depth 2.5 3 mAir Requirement 47 47 CFM.Blower / SurfaceAerator Capacity

25 25 CFM

No of Blowers /Aerators

2 2 No

Secondary Sedimentation TanksNo of Tanks - 1 NoSurface area - 4 m2

Depth - 2.5 mSludge Digester

No of Tanks 1 No.Surface area 48 m2

Depth 6.5 mSludge Drying Beds

No of Tanks 2 2 No.Surface area 12 12 m2

Depth 1 1 m

Table 5.4: Cost Estimates for SecondaryTreatment System

Cost In Rs.Components

Option 1 Option 2

Civil work 1,660,000 900,000Piping, mechanical & electrical

equipment

250,000 430,000

Contingencies @ 15 % 300,000 200,000Total 2,210,000 1,530,000

Operational and maintenance

per annum

150,000 300,000

Non process wastewater

By observing good housekeeping this water can be keptfree of all pollutants, except for TDS. TDS can only be

removed by reverse osmosis (R.O), and the water can berecycled but R.O. treatment is very expensive.

5.2 Solid WasteMeasures, which could be taken to reduce and properly

handle the solid wastes, are given in the following sections:

5.2.1 Improvement of Waste Management and Land FillingThere are a number of possibilities available for improving

the present waste management system. The investmentinvolved in such improvements is limited, as many of them

are related to good working practices.

It is of the utmost importance for a food industry to offer aclean and hygienic surrounding. In order to guarantee this,

waste management procedures should be issued out andimplemented. Furthermore, the management should ensure

that the procedures are regularly followed by workers.

The behaviour of each type of waste and the potential risks to

environment and human health differ very much, therefore,they must be managed, stored and disposed off separately.

The control measures that can be implemented to improvethe present situation are stated below.

a) Domestic/General waste::

It is recommended that containers should be provided toavoid uncontrolled dumping of waste inside the plant. Closedcontainers should be used to prevent the spillage of waste

and to avoid odour nuisance. Furthermore, it isrecommended to increase the awareness of employees

regarding waste by arranging a certain number of short andinformal training sessions for all employees and by placing

posters in strategic places, such as: canteen, tea shop, near

the waste containers, etc.

The containers must be regularly collected and emptied at a

local landfill, to avoid over spillage and dumping of waste inthe containers surroundings.

b) T in scrap:

The management for tin waste can be improved to get moretidy and organised storage in the factory. In order to get a

better price for the recycled tin, it is recommended to avoidmixing it with other kind of waste and avoid longer storage

time.


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Figure 5.1: Gravity Settling Tank

Figure 5.2: Chemically Enhanced Dissolved Air Flotation

Figure 5.3: Process Flow Diagram of Activated Sludge System


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c) Sludge fr om water ponds, fat traps and raw oil tanks:

Water ponds: It is recommended to clean the waterponds once every two months, and to dispose offthis sludge in a municipal waste landfill.

Fat traps: It is recommended to clean the fat trapsregularly (once every 3 months). The sludge

generated as a result of this cleaning process can be

used in the soap section.

Raw Oil Tanks: It is recommended that raw oil tanksbe cleaned every 3 months, so that the layer of

sludge at the bottom of the tank is as thin aspossible. By keeping the sludge layer thin, the

degradation of oil is minimised and the formation ofsludge is, therefore, minimised.

d) Spent earth:Cleaning activity of the scraped earth from process buildingcan be simplified by installing an external vertical chute and

a storage area down the chute, so that the spent earth can bedischarged out of the building through a window and the

chute. It is recommended to cover the area where the spentearth is piled with a simple roof to avoid getting it wet during

rains and dispersion by wind and water.

e) Spent lubricants:

Spent oil and lubricants are considered hazardous waste and

should only be sold to an authorised waste dealer, who isresponsible for its correct treatment.

5.2.2 Use of Tankers with Internal Coils toMinimise Sludge

To avoid oil losses and to minimise sludge formation, the tank

trucks must be provided with proper insulation and internalheating coils. This could reduce the oil losses during storage

and handling by 50 %. This reduction can be estimated astotal oil loss savings of about 0.05% of the oil processed.

Providing internal coils to tank trucks would be a difficult task

to be performed by a single mill, and it is very difficult toforce the carrier to make the investment needed for that.

However, this is something that could be discussed and doneon a sectoral basis.

5.2.3 Increased Recycling of Nickel Catalysts

Nickel catalyst is presently being recycled at a ratio of 90%fresh to 10% recycled in some industries. This recycling ratio

is very low. Normally, edible oil mills reuse up to 80% ofrecycled catalyst. It is recommended to perform some trials

with increased catalyst recycling in order to see what is themaximum recycling ratio that can be achieved.

Another possibility for improving nickel catalyst recovery is

the use of centrifugal separators instead of filter press.

5.2.4 Recovery of Oil from Spent Earth

Oil mills are presently producing carbon oil from spent earth

by adding caustic soda and heating. This way the oil content

in spent earth is used to make a by-product, while at leastpart of this oil content can be recovered as a product, i.e.

edible oil. This can be done in

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