PENGOLAHAN LIMBAH SECARA KIMIAWI

1. Reaction to produce an insoluble solid

2. Reaction to produce an insoluble gas

3. Reduction of surface charge to produce coagulation of a

colloidal suspension

4. Reaction to produce a biologically degradable substance

from a nonbiodegradable subs.

5. Reaction to destroy or deactivate a chelating agent

6. Oxidation or reduction

Six chemical processes :

• Removing metals alkaline precipitations,

precipitation of the metal as the sulfide,

precipitation as the phosphate, precipitation as

the carbonate, or co-precipitation with another

metal hydroxide, sulfide, phosphate, or

carbonate.

1. Reaction to produce an insoluble solid

Chemical substancesChemical Application

Lime Heavy metals, fluoride, phosporus

Soda Ash Heavy metals

Sodium sulfide Heavy metals

Hydrogen sulfide Heavy metals

Phosporic acid Heavy metals

Fertilizer grade phosphate Heavy metals

Ferric sulfate Arsenic, sulfide

Ferric chloride Arsenic, sulfide

Alum Arsenic, fluoride

Sodium sulfate Barium

1. Reaction to produce an insoluble solid

Raw Waste

pH adjust

Oxidation or

chelating agent

destruct

pH adjust or

Chem addition

Floc

Sed Filt

Sludge Dewater, Dry

Conditioning

Steps

Return For Seed

Schematic for Removal by forming an insoluble substances

• If produce insoluble gas it will remove itself from solution as it is formed

• Ex :

2 NO2- + Cl2 + 8 H+ N2 + 4H2O + 2 Cl-

• Chlorine added in the form of chlorine gas or hypochlorite, or another chloride compound that dissolves in water

2. Reactions to Produce an Insoluble Gas

Chemical substances

CHEMICAL SUBSTANCE

TREATMENT TECHNOLOGY

Chlorine gas or other chlorine compound (hypochlorite, or chlorine dioxide)

(1). Breakpoint chlorination to remove ammonia

(2). Alkaline chlorination of cyanide

Sulfuric or hydrochloric acids (technical grade or waste acids)

Removal of sulfide as hydrogen sulfide gas

2. Reactions to Produce an Insoluble Gas

• Industrial wastewater consists of colloidal

suspensions

• Destabilized industrial wastewater by

chemical coagulation allow separation

of destabilized colloidal material from

water

3. Reduction of surface charge to produce coagulation of a colloidal suspension

• Unbiodegradable substances altered to

biodegradable materials

• Hydrolysis (acid or alkaline) break up large

organic molecules into smaller segments

• Ex: Substances from cellulose or derivatives acid

hydrolysis + heat

4. Reaction to produce a biologically degradable substance from a nonbiodegradable subs.

• Chelating agents : organic materials (EDTA) or inorganic

materials (polyphosphates)

• ORGANIC CHELATING AGENTS :

– Destroy by acid hydrolysis

– Destroy by hydroxyl free radical oxidation :• Fenton’s reagent (H2O2 + ferrous ions)

• Hydrogen peroxide + UV light

• Ozone + hydrogen peroxide

• Ozone + UV light

– Destroy by adding potassium permanganate + heating

– Pass the wastewater through granular activated carbon

5. Reaction to destroy or deactivate a chelating agent

• Senyawa yg tidak diijinkan dapat dioksidasi secara kimia, menjadi CO2 dan H2O

• Contoh :– Menghilangkan chromium reducing

hexavalent chrome ions (soluble in water & highly toxic) menjadi bentuk trivalent

• Reducing agents : SO2, sodium/potasium bisulfit, or metabisulfit, and sodium or potasium bisulfit plus hydrazine.

• pH acid range

6. Oxidation or reduction to produce a non objectionable subs.

• Kelebihan pengolahan secara kimia:– Efisiensi tinggi (dapat mencapai angka yang

diinginkan)– Waktu dentensi relatif singkat sehingga volume

reaktor/unit pengolahan relatif lebih kecil

• Kekurangan– Ada penambahan zat aditif sehingga meningkatkan

konsentrasi Total Dissolved Solid (TDS). Penyisihan TDS relatif sulit dan mahal: membran atau destilasi

– Meningkatkan beban pengolahan– Biaya bahan kimia cukup mahal = biaya untuk energi

Chemical treatment

I. Introduction

A. Reasons to Soften

1. Reduce Soap Consumption

2. Improve Aesthetics of Water

B. Reasons not to Soften

1. Expensive Process

2. May be less healthy

3. Hot Water Heaters last longer

Water Softening

3. Competes with health related costs

II. What is Hardness?

C. Carbonate Hardness as CaCO3 = T. Alkalinity as CaCO3

D. Non-Carbonate Hardness = T. Hardness – T. Alkalinity

Water Softening

a. Removed by Boiling

b. Removed by Lime

a. Unaffected by boiling

b. Removed by Soda Ash

B. T. Hardness, mg/L, as CaCO3 = (Ca X 2.5) + (Mg X 4.12) (MW=100) (40 X 2.5 = 100) (24.3 X 4.12 = 100)

A. Hardness Classifications

a. Soft Water = 0 to 70 mg/L

b. Moderate Hardness = 71 to 150 mg/L

c. Hard Water = > 150 mg/L

Water Softening

III. Methods of Softening

A. Lime-Soda Ash Chemistry1. 1st Stage Treatment (Lime only)

* CO2 + Ca(OH)2 CaCO3 + H2O

* Ca + 2HCO3 + Ca(OH)2 2CaCO3 + 2H2O(pH 8.3-9.4)

* Mg + 2HCO3 + Ca(OH)2 CaCO3 + Mg + CO3 + 2H2O(pH >10.8)

a. Carbon Dioxide Removal (< 8.3 pH)

b. Carbonate Hardness Removal

c. Magnesium Hardness Removal (>pH 10.8)

* Mg + CO3 + Ca(OH)2 CaCO3 + Mg(OH)2

* Mg + SO4 + Ca(OH)2 Ca + SO4 + Mg(OH)2

* Ca + SO4 + Na2CO3 Na2SO4 + CaCO3

2. 2nd Stage Treatment (Soda Ash)

* Ca + Cl2 + Na2CO3 CaCO3 + 2NaCl

PENGOLAHAN LIMBAH SECARA BIOLOGI

• Proses yang menggunakan bahan organik sebagai

makanan bagi bakteri atau m.o lain

bakteri, fungi, rotifera

• O2 dibutuhkan baik dalam bentuk yg larut ataupun anion

spt sulfat dan nitrat (aerobik)

• Produk akhir : penurunan jumlah polutan organik,

meningkatnya jumlah m.o, CO2, H2O, by-products

• Sebagai pengolahan sekunder, pengolahan secara biologi

dipandang sebagai pengolahan yang paling murah dan

efisien.

• Proses secara biologi berlangsung selama 1-7 hari

Pengolahan limbah secara biologi

Pengolahan limbah secara biologi

• Jika bakteri berasal dari limbah maka yang tumbuh

bermacam-macam jenis bakteri dari mulai yang bersifat

patogen maupun probiotik.

• Dalam kondisi semacam ini maka proses hanya dapat

berlangsung secara aerobik.

AEROBIK

Mikroorganisme

Microbial Metabolism

• General nutritional requirements -:• Carbon Substrate (Org. Or Inorg.)• Electron Donor• Energy Source

• Need for molecular oxygen.• Basic elements required-C,O ,N,H, P,S• Inorganic elements: K,Mg,Ca,Fe,Na,Cl

-

SINGLESINGLE BACTERIUMBACTERIUM

2.0m

ORGANIC ORGANIC POLLUTANTPOLLUTANTAND NUTRIENTSAND NUTRIENTS(C,P,N,O,Fe,S…)(C,P,N,O,Fe,S…)

GROWTH - CELL DIVISIONGROWTH - CELL DIVISIONINCREASE IN BIOMASSINCREASE IN BIOMASS(assimilation)(assimilation)

COCO22 evolved evolved

(dissimilation)(dissimilation)

OO22

consumptionconsumption

Controlled release of energyControlled release of energySlow Burning!Slow Burning!

Mikroorganisme

Mikroorganisme

• Bakteri • Fungi

• Nemotodes

• Algae

• Protozoa • Rotifera

Mikroorganisme

Pengaruh kondisi lingkungan

Bioreaktor (untuk pengolahan limbah)

• Terdiri dari berbagai jenis mikroba

• Mikroba tersuspensi dalam limbah

• Jumlah mikroba dapat terkontrol dengan baik

mudah diuji di lab

• Contoh: Activated sludge : proses aerobik

termasuk oksidasi karbon dan nitrifikasi

• Disertai flokulasi mikroba diikuti filtrasi dan

sedimentasi

Suspended Growth

screens Grit chamber

PrimarySettling

tankaeration chlorination

Raw water

SecondarySettling

tank

Effluentto disposal

Reareation

Activated Sludge Pump

Activated Sludge return

SludgeThickener

Sludge Digestion To Sludge Drying

Flow Diagram of ASP

• Screening and Grit Units : to remove large objects and to reduce particle size

• Primary Settling Tanks : to remove particles from water sedimentation– Particulates suspended size : 10-1 to 10-7 mm– ( > 10-4 : turbidity ; < 10-4 : color & taste)– 70% of the solids and 30% of the BOD can be removed

• Aeration Tanks : provides 6 to 24 hours retention – The contents mixed liquor, and the solids are called mixed liquor

suspended solids (MLSS), living and dead microbial cells– microorganisms kept in suspension 4 to 8 hr (by mechanical

mixers and/or diffused air), – M.o concentration maintained by the continuous return of the

settled biological floc from a secondary settling tank to the aeration tank.

Lumpur aktif

• Final Settling Tanks : provide longer detention (2h) and lower overflow rates (30 to 50 m3/m2.day)

• the sludge settles to the bottom of the tank still active and able to

remove more BOD from the waste water maintains and

increases the microorganism concentration in the aeration chamber

– key factor to increase BOD removal from the waste water

• << 24 hr in the aerobic process BOD concentration should not

exceed about 2,000 mg/l on the effluent

• Thickener : part of the separation of the activated sludge

from the mixed liquor in the secondary clarifiers

– Type of thickeners Gravity Thickening, Thickening by

Flotation, and Centrifugal Thickening

– reduce sludge volume by 50 - 70%

Lumpur aktif

Advantages• Diverse; can be used for one household up a huge plant

• Removes organics

• Oxidation and Nitrification achieved

• Biological nitrification without adding chemicals

• Biological Phosphorus removal

• Solids/ Liquids separation

• Stabilization of sludge

• Capable of removing ~ 97% of suspended solids

• The most widely used wastewater treatment process

Suspended Growth

Disadvantages

• Does not remove color from industrial wastes and may

increase the color through formation of highly colored

intermediates through oxidation

• Does not remove nutrients, tertiary treatment is

necessary

• Problem of getting well settled sludge

• Recycle biomass keeps high biomass concentration in

aeration tanks allowing it to be performed in

technologically acceptable detention times

Suspended Growth

Seluruh modifikasi ini dapat menghasilkan efisiensi penurunan BOD sekitar 80%-90%.

Attached Growth

• All microbes attached to the medium

batu, plastik, dll

• The microbes able to access the organis

matter in the waste water

• Trickling filter, RBC, Fluidized bed

Attached Growth

• Terdiri dr lapisan batu dan kerikil dgn tinggi 90 cm-3 m

• Air limbah dialirkan secara perlahan melalui lapisan ini.

• Bakteri akan terkumpul & berkembang biak pd batu dan kerikil mengkonsumsi bahan organik yg terdapat dlm air limbah

Penyaring Trikel

Penyaring Trikel

Pretreatment

PrimaryTreatment

RotatingBiological

Contactors

SecondaryClarifiers

Solids Handling

INFLUENTINFLUENT

Disinfection

EFFLUENTEFFLUENT

RBC Flow Scheme

RBC Secondary Treatment

Plastic Media

1.6 rpm

40 %Submerged

Microorganisms “Treat” the Wastewater by Using Organics

Provides Large Surface Area

Rotating

CONTACTORCONTACTOR

ShaftIndividual Disc

Discs

RBC COMPONENTS

• Anaerobic digestion is widely used to treat wastewater

sludges and organic wastes because it provides volume

and mass reduction of the input material.

• Anaerobic digestion is a renewable energy source

because the process produces a methane and carbon

dioxide rich biogas suitable for energy production helping

replace fossil fuels. Also, the nutrient-rich solids left after

digestion can be used as fertiliser.

Anaerobic digestion

• The digestion process begins with bacterial hydrolysis of the input materials in order to break down insoluble organic polymers such as carbohydrates and make them available for other bacteria.

• Acidogenic bacteria then convert the sugars and amino acids into carbon dioxide, hydrogen, ammonia, and organic acids.

• Acetogenic bacteria then convert these resulting organic acids into acetic acid, along with additional ammonia, hydrogen, and carbon dioxide.

• Methanogens, finally are able to convert these products to methane and carbon dioxide.

Anaerobic digestion

The key process stages of anaerobic digestion

There are four key biological and chemical stages of anaerobic digestionHydrolysis

Acidogenesis Acetogenesis

Methanogenesis

A simplified generic chemical equation for the overall processes outlined

above is as follows:

C6H12O6 → 3CO2 + 3CH4

• Slow rate process required long times

retention

• For waste of high organic strength --?

COD > 2000 ppm

• Capable treating some substances

cellulosic materials, aromatic compounds,

chlorinated solvents

Anaerobic digestion

Aerobic vs Anaerobic

• Pengolahan secara biologi yang tidak tepat akan menyebabkan timbulnya bau busuk dan penggumpalan bahan berlemak. Jika tidak diatasi segera maka akan sangat mengganggu.

• Untuk menghindari proses pengolahan limbah yang tidak efektif dilakukan terlebih dahulu pre-treatment dengan tujuan agar tidak terjadi over load COD, diusahakan agar  COD maksimal 2000 ppm.

• Tujuan pre-treatment adalah agar beban COD lebih rendah dan limbah lebih homogen.

Apa akibat dari proses biologi yang tidak tepat pada pengolahan limbah cair ?

TERIMA KASIH