UNIVERSITY OF BENINFACULTY OF ENGINEERINGDEPARTMENT OF CHEMICAL ENGINEERING

WASTE DISPOSAL AND EFFLUENT TREATMENTS

BYGROUP VIII

SUPERVISED BY: PROF. OBAHIAGBONCHE 522

Waste-What is it?The term is often subjective (because waste to one person is not necessarily waste to another) and sometimes objectively inaccurate (for example, to send scrap metals to a landfill is to inaccurately classify them as waste, because they are recyclable). Examples include municipal solid waste (household trash/refuse), hazardous waste, wastewater (such as sewage, which contains bodily wastes, or surface runoff), radioactive waste, and others.Some definitions of Waste include the followings:1. According to the Basel Convention, an international treaty that was designed to reduce the movements of hazardous waste between nations, and specifically to prevent transfer of hazardous waste from developed to less developed countries (LDCs): "'Wastes' are substances or objects, which are disposed of or are intended to be disposed of or are required to be disposed of by the provisions of national law".2. According to the United Nations Statistics Division, Glossary of Environment Statistics: "Wastes are materials that are not prime products (that is products produced for the market) for which the initial user has no further use in terms of his/her own purposes of production, transformation or consumption, and of which he/she wants to dispose. Wastes may be generated during the extraction of raw materials, the processing of raw materials into intermediate and final products, the consumption of final products, and other human activities. Residuals recycled or reused at the place of generation are excluded."3. According to the European Union, under the Waste Framework Directive, the European Union defines waste as "an object the holder discards, intends to discard or is required to discard."From the above definitions, one thing is common among them which is that waste and wastes implies unwanted or unusable materials.

Fig. 1 Schematic illustration of the EU Legal definition of waste

EffluentsEffluent is an outflowing of water or gas from a natural body of water, or from a human-made structure. In engineering, it is the stream exiting a chemical reactor. Effluent is defined by the United States Environmental Protection Agency (EPA) as wastewater - treated or untreated - that flows out of a treatment plant, sewer, or industrial outfall. It generally refers to wastes discharged into surface waters.

.TYPES AND SOURCES OF WASTE TYPESGenerally, waste could be liquid or solid waste. Both of them could be hazardous. Liquid and solid waste types can also be grouped into organic, re-usable and recyclable waste. Let us see some details below:Liquid type:Waste can come in non-solid form. Some solid waste can also be converted to a liquid waste form for disposal. It includes point source and non-point source discharges such as storm water and wastewater. Examples of liquid waste include wash water from homes, liquids used for cleaning in industries and waste detergents.Solid type:Solid waste predominantly, is any garbage, refuse or rubbish that we make in our homes and other places. These include old car tires, old newspapers, broken furniture and even food waste. They may include any waste that is non-liquid.Hazardous type:Hazardous or harmful waste are those that potentially threaten public health or the environment. Such waste could be inflammable (can easily catch fire), reactive (can easily explode), corrosive (can easily eat through metal) or toxic (poisonous to human and animals). In many countries, it is required by law to involve the appropriate authority to supervise the disposal of such hazardous waste. Examples include fire extinguishers, old propane tanks, pesticides, mercury-containing equipment (e.g, thermostats) and lamps (e.g. fluorescent bulbs) and batteries. Organic type:Organic waste comes from plants or animals sources. Commonly, they include food waste, fruit and vegetable peels, flower trimmings and even dog poop can be classified as organic waste. They are biodegradable (this means they are easily broken down by other organisms over time and turned into manure). Many people turn their organic waste into compost and use them in their gardens. SOURCESThere are various sources of wastes. Some of these include the following: Municipal wastes:commonly known as trash or garbage (US), refuse or rubbish (UK) is a waste type consisting of everyday items that are discarded by the public. "Garbage" can also refer specifically to food waste, as in a garbage disposal; the two are sometimes collected separately. Municipal wastes can be classified as: Food wastes, e.g., animal, fruit or vegetable leftovers Rubbish, e.g., combustible and non-combustible solid wastes, excluding food wastes or putrescible materials. Ashes and Residues, e.g., materials remaining from burning of wood, coal, coke, and other combustible wastes. Industrial wastes:Industrial waste is the waste produced by industrial activity which includes any material that is rendered useless during a manufacturing process such as that of factories, mills and mining operations or excavation. It has existed since the outset of the industrial revolution. Some examples of industrial waste are chemical solvents, paints, sand paper, paper products, industrial by-products, metals, and radioactive wastes. Toxic waste, chemical waste, industrial solid waste and municipal solid waste are designations of industrial waste. Agricultural wastes: Agricultural wastes, which may include horticultural and forestry wastes, comprise crop residues, animal manure, diseased carcasses, unwanted agrochemicals and empty containers. Their composition depend on the system of agriculture. Mining and Quarrying wastes: Mine tailings or spoils are the waste material that is extracted in the process of mining minerals of economic value such as gold, diamonds, and other precious earth metals. Bio-hazardous wastes: Also called infectious wastes or bio-medical wastes, it is any waste containing infectious materials or potentially infectious substances such as blood. Of special concern are sharp wastes such as needles, blades, glass pipettes and other wastes that can cause injury during handling. Radioactive wastes: these are wastes that contain radioactive materials. They are usually byproducts of nuclear power generation and other applications of nuclear fission or nuclear technology, such as research and medicine. Examples include uranium mill tailings which contain heavy metals such as lead and arsenic.

WASTE DISPOSAL MANAGEMENTWaste management is the process of treating solid wastes and offers variety of solutions for recycling items that dont belong to trash. It is about how garbage can be used as a valuable resource. Waste management is something that each and every household and business owner in the world needs. Waste management is the generation, prevention, characterization, monitoring, treatment, handling, reuse and residual disposition of solid wastes. There are various types of solid waste including municipal (residential, institutional, commercial), agricultural, and special (health care, household hazardous wastes, sewage sludge).Waste disposal management continues to be a rising challenge as population grows and along with the industrial development of countries. Centuries ago, people would have the trash from their homes transported and dumped in the places far away from the city of village. Today, instead of open dumping, usually the trash is collected and transported to landfills and then buried. Of course, over these hundreds of years, processes have certainly become more sophisticated. Instead of just burying the trash in landfills, we also use methods like plasma gasification, ocean dumping, incineration and recycling. Let's take a look at a few of them.WASTE DISPOSAL METHODSLandfillAmongst the many waste management methods, using a landfill is probably the most practiced in more areas of the world than any other method. Landfills are often old and abandoned quarries and mining areas. Considered the most cost-effective way of waste disposal, about 75% of the cost of implementation is attributable to the collection and transportation of waste from residential and businesses to the landfills. The waste is layered in thin spreads and then compacted, with a layer of clean earth covering the waste material before more layers are added over time.IncinerationIncineration as a disposal method involves burning the trash. Sometimes this is simply referred to as thermal treatment, as a general category of high temperature treatment of trash material. This method can be used to transform waste into heat, gas, steam and ash. One of the advantages of incineration is that with this method, refuse volume can be reduced by half or more and it requires little usage of land. An incineration facility can be built in a small area to process huge amounts of waste. It definitely saves a lot of space compared with using a landfill only. This method is popular in countries like Japan where space is limited.RecyclingRecycling of waste material means taking the materials and transforming them into new products. This is a key concept in the modern waste minimization philosophy. It's about lessening the strain on the environment through minimizing the need to fully dispose (eg. by incineration and causing air pollution) of the waste generated and reducing the need to introduce new raw materials into the environment and then having to dispose of them later. In your everyday living, you may already be separating out paper products, aluminum soda cans or glass bottles into different waste containers so that these could be recycled. When bring your own shopping bag to the supermarket instead of using a new plastic bag, that's another way of recycling.ADVANTAGES AND DISADVANTAGES OF WASTE DISPOSAL METHODSOCEAN DUMPING

Advantages: convenient inexpensive source of nutrients, shelter and breeding Disadvantages: ocean overburdened destruction of food sources killing of plankton desalination

SANITARY LANDFILL

Advantages: volume can increase with little addition of people/equipment filled land can be reused for other community purposes Disadvantages: completed landfill areas can settle and requires maintenance requires proper planning, design, and operation

INCINERATION

Advantages: requires minimum land can be operated in any weather produces stable odor-free residue refuse volume is reduced by half Disadvantages: expensive to build and operate high energy requirement requires skilled personnel and continuous maintenance unsightly - smell, waste, vermin

OPEN DUMPING

Advantages: inexpensive Disadvantages: health-hazard - insects, rodents etc. damage due to air pollution ground water and run-off pollution

RECYCLING

Advantages: key to providing a livable environment for the future Disadvantages: expensive some wastes cannot be recycled technological push needed separation of useful material from waste difficult

EFFLUENT TREATMENTEffluent is an outflowing of water or gas from a natural body of water, or from a human-made structure.Effluent, in engineering, is the stream exiting a chemical reactor.Effluent is defined by the United States Environmental Protection Agency as wastewater - treated or untreated - that flows out of a treatment plant, sewer, or industrial outfall.

Brewery industry EFFLUENTWastewater from Brewery Industry originates from liquors pressed from grains and yeast recovery and have the characteristic odour of fermented malt and slightly acidic. Brewery effluents are high in carbohydrates; nitrogen and the cleaning and washing reagents have been proved water pollutants.OIL REFINERY EFFLUENTThe basic constituents of oil refinery effluents are hydrocarbon. Other materials include:Organic materials (phenols, alcohols), Sulphuric compounds (sulphide, mercaptan, sulphate), Sodium salts, Suspended solidsMINING AND PROCESSING CHEMICAL EFFLUENT:Effluent from mining and chemical processing industries include:Iron and steel industry: the production of iron from its ores involves powerful reduction reactions in blast furnaces. Cooling waters are inevitably contaminated with products especially ammonia and cyanide. Production of coke from coal in coking plants also requires water cooling and the use of water in by-products separation. Contamination of waste streams includes gasification products such as benzene, naphthalene cyanide, ammonia, phenols cresols, together with range of more complex organic compounds known collectively as polycyclic aromatic hydrocarbons (PAH).

PAPER MILL EFFLUENTImpact on the environment are classified into three: air, water, and land pollution.Air emission: the characteristic odor associated with pulp mill employing Kraft process is due to hydrogen sulphide, dimethyl sulphide, other compounds release into the air and water are carbon monoxide, ammonia, nitrogen oxide, methanol, chloroform, etc.Water pollution: waste water discharge from pulp and paper mill basically contains solids, dissolved organic matter such as lignin, alcohols, and inorganic materials like chlorates and transition metal compounds, and additional hazard of toxic inks, dyes and polymers. Some of these are naturally occurring in the wood, but chlorine bleaching of the pulp produces far larger amounts.Land pollution: Recycling (de-inking process) produces sludge (containing toxic metals such as lead, arsenic, selenium, mercury, cadmium and hexavalent chromium.) which can typically weigh 22% of the of wastepaper recycled.TREATMENT METHODS: Bioremediation ponds (depending on the effluent content), Coagulation method, Oxidation method using heterogeneous catalysts for the removal non-biodegradable and toxic compounds e.g wet air oxidation using CuO-ZnO as catalyst. Decolourization and Degradation method

TEXTILE MILL EFFLUENTTextile industry involves wide range of raw materials, machineries and processes to engineer the required shape and properties of the final product. Waste stream generated in this industry is essentially based on water-based effluent generated in the various activities of wet processing of textiles. The main cause of generation of this effluent is the use of huge volume of water either in the actual chemical processing or during re-processing in preparatory, dyeing, printing and finishing.CATEGORY OF WASTE GENERATED IN TEXTILE INDUSTRY1. Hard to Treat Wastes: This category of waste includes those that are persistent, resist treatment, or interfere with the operation of waste treatment facilities. Non-biodegradable organic or inorganic materials are the chief sources of wastes, which contain colour, metals, phenols, surfactants, toxic organic compounds, pesticides and phosphates. The chief sources are: Colour & metal fromdyeing operation Phosphates frompreparatory processes and dyeing Non-biodegradable organic materials fromsurfactants

2. Hazardous or Toxic Wastes: These wastes are a subgroup of hard to treat wastes. But, owing to their substantial impact on the environment, they are treated as a separate class. In textiles, hazardous or toxic wastes include metals, chlorinated solvents, non-biodegradable or volatile organic materials. Some of these materials often are used for non-process applications such as machine cleaning.

3. High Volume Wastes: Large volume of wastes is sometimes a problem for the textile processing units. Most common large volumewastes include: High volume of waste water, Wash water from preparation and continuous dyeing processes and alkaline wastes from preparatory processes, Batch dye waste containing large amounts of salt, acid or alkali.

4. Dispersible Wastes: The following operations in textile industry generate highly dispersible waste: Waste stream from continuous operation (e.g. preparatory, dyeing, printing and finishing) Print paste (printing screen, squeeze and drum cleaning) Lint (preparatory, dyeing and washing operations) Foam from coating operations Solvents from machine cleaning Still bottoms from solvent recovery (dry cleaning operation) Batch dumps of unused processing (finishing mixes)CLASSIFICATION OF WASTE WATER TREATMENT PROCESS

1. Primary Treatment Operations: Screening Sedimentation Neutralisation Mechanical flocculation & Chemical coagulation2. Secondary Treatment Operations: Trickling filtration Activated sludge process Oxidation ditch & pond Anaerobic digestion

3. Tertiary Treatment Operations: Oxidation technique Electrolytic precipitation & Foam fractionation Membrane technologies Electrochemical processes Ion exchange method Photo catalytic degradation Adsorption (Activated Carbon etc.) Thermal evaporation

PHARMACEUTICAL EFFLUENTEffluent from pharmaceutical industry are mainly water based (waste water effluent), content of which vary from suspended solid, organic compound, to inorganic matter. TREATMENT METHODS: Biological treatment methods (Conventional treatment method)

Physio-chemical treatment options Membrane processes Activated carbon (adsorption method) Chlorination Oxidation reactions Ozonation Perozonation (a combination of hydrogen peroxide and ozone) Fenton reactions, Direct photolysis, Photocatalysis Electrochemical treatment optionsFOOD INDUSTRY EFFLUENTThe characteristics and volume of wastewater discharged from food processing factories vary with the products and production procedures. In factories like accompanying dishes makers and beverage makers, due to changes of products and/or production the wastewater fluctuates in characteristics and volume. Almost all the wastewater in food processing factories is treated using a biological treatment process. The characteristics of wastewater from food processing factories are characterized by high BOD, and oil concentrations as well as emitting smells from acidification. Aerobic or anaerobic biological processes are applied to wastewater treatment in food processing factories, removing oils and solids prior to the biological process is important for preventing them from disturbing the treatment. TREATMENT METHODS: Brewery and Beverage industry: Aerobic and Anaerobic biological treatment Vegetable oil industry: oil separation, Aerobic and Anaerobic biological treatment Milk/ Dairy product, Starch, Daily dishes, and Confectionary: Aerobic biological treatment

TREATMENT OF INDUSTRIAL EFFLUENTSThe various types of contamination of wastewater require a variety of strategies to remove the contamination. Brine treatmentBrine treatment involves removing dissolved salt ions from the waste stream. Although similarities to seawater or brackish waterdesalinationexist, industrial brine treatment may contain unique combinations of dissolved ions, such as hardness ions or other metals, necessitating specific processes and equipment.Brine treatment systems are typically optimized to either reduce the volume of the final discharge for more economic disposal (as disposal costs are often based on volume) or maximize the recovery of fresh water or salts. Brine treatment systems may also be optimized to reduce electricity consumption, chemical usage, or physical footprint.Brine treatment is commonly encountered when treating cooling tower blowdown, produced water fromnatural gasextraction such ascoal seam gas, frac flowback water,acid mine or acid rock drainage, reverse osmosis reject,chlor-alkaliwastewater, pulp and paper mill effluent, and waste streams from food and beverage processing.Brine treatment technologies may include: membrane filtration processes, such asreverse osmosis; ion exchange processes such aselectrodialysisorweak acid cation exchange; or evaporation processes, such as brine concentrators andcrystallizersemployingmechanical vapour recompressionand steam.Reverse osmosismay not be viable for brine treatment, due to the potential for fouling caused by hardness salts or organic contaminants, or damage to the reverse osmosis membranes fromhydrocarbons.Evaporation processes are the most widespread for brine treatment as they enable the highest degree of concentration, as high as solid salt. They also produce the highest purity effluent, even distillate-quality. Evaporation processes are also more tolerant of organics, hydrocarbons, or hardness salts. However, energy consumption is high and corrosion may be an issue as the prime mover is concentrated salt water. As a result, evaporation systems typically employtitaniumorduplex stainless steelmaterials. Solids removalMost solids can be removed using simple sedimentation techniques with the solids recovered asslurryor sludge. Very fine solids and solids with densities close to the density of water pose special problems. In such case filtration orultrafiltrationmay be required. Although,flocculationmay be used, usingalumsalts or the addition ofpolyelectrolytes. Oils and grease removalMany oils can be recovered from open water surfaces by skimming devices. Considered a dependable and cheap way to remove oil, grease and other hydrocarbons from water, oil skimmers can sometimes achieve the desired level of water purity. At other times, skimming is also a cost-efficient method to remove most of the oil before using membrane filters and chemical processes. Skimmers will prevent filters from blinding prematurely and keep chemical costs down because there is less oil to process.Because grease skimming involves higher viscosity hydrocarbons, skimmers must be equipped with heaters powerful enough to keep grease fluid for discharge. If floating grease forms into solid clumps or mats, a spray bar, aerator or mechanical apparatus can be used to facilitate removalHydrocyclone Oil Separators:Hydrocyclone oil separators operate on the process where wastewater enters the cyclone chamber and is spun under extreme centrifugal forces up to 1000 times the force of gravity. This force causes the water and oil droplets to separate. The separated oil is discharged from one end of the cyclone where treated water is discharged through the opposite end for further treatment, filtration or discharge. Treatment of acids and alkalisAcids and alkalis can usually beneutralisedunder controlled conditions. Neutralisation frequently produces aprecipitatethat will require treatment as a solid residue that may also be toxic. In some cases, gasses may be evolved requiring treatment for the gas stream. Some other forms of treatment are usually required following neutralisation.Waste streams rich inhardnessions as from de-ionisation processes can readily lose the hardness ions in a buildup of precipitated calcium and magnesium salts. This precipitation process can cause severefurringof pipes and can, in extreme cases, cause the blockage of disposal pipes. A 1 metre diameter industrial marine discharge pipe serving a major chemicals complex was blocked by such salts in the 1970s. Treatment is by concentration of de-ionisation waste waters and disposal to landfill or by careful pH management of the released wastewater. Treatment of toxic materialsToxic materials including many organic materials, metals (such as zinc, silver,cadmium,thallium, etc.) acids, alkalis, non-metallic elements (such as arsenic orselenium) are generally resistant to biological processes unless very dilute. Metals can often be precipitated out by changing the pH or by treatment with other chemicals. Many, however, are resistant to treatment or mitigation and may require concentration followed by landfilling or recycling. Dissolved organics can beincineratedwithin the wastewater by the advanced oxidation process.

Removal of biodegradable organicsBiodegradable organic material of plant or animal origin is usually possible to treat using extended conventional sewageprocesses such asactivated sludgeortrickling filter. Problems can arise if the wastewater is excessively diluted with washing water or is highly concentrated such as undiluted blood or milk. The presence of cleaning agents, disinfectants, pesticides, or antibiotics can have detrimental impacts on treatment processes.Activated sludge processActivated sludge is abiochemicalprocess for treating sewage and industrial wastewater that uses air (oroxygen) andmicroorganismsto biologically oxidize organic pollutants, producing a waste sludge (orfloc) containing the oxidized material. In general, an activated sludge process includes: An aeration tank where air (or oxygen) is injected and thoroughly mixed into the wastewater. A settling tank (usually referred to as aclarifieror "settler") to allow the waste sludge to settle. Part of the waste sludge is recycled to the aeration tank and the remaining waste sludge is removed for further treatment and ultimate disposal.

Trickling filter processAtrickling filterconsists of a bed ofrocks,gravel,slag,peat moss, or plastic media over which wastewater flows downward and contacts a layer (or film) ofmicrobialslime covering the bed media.Aerobicconditions are maintained by forced air flowing through the bed or by natural convection of air. The process involvesadsorptionof organic compounds in the wastewater by the microbial slime layer, diffusion of air into the slime layer to provide the oxygen required for the biochemical oxidationof the organic compounds. The end products includecarbon dioxidegas, water and other products of the oxidation. As the slime layer thickens, it becomes difficult for the air to penetrate the layer and an inner anaerobic layer is formed.The fundamental components of a complete trickling filter system are: A bed of filter medium upon which a layer of microbial slime is promoted and developed. An enclosure or a container which houses the bed of filter medium. A system for distributing the flow of wastewater over the filter medium. A system for removing and disposing of any sludge from the treated effluent.The treatment of sewage or other wastewater with trickling filters is among the oldest and most well characterized treatment technologies.

QUALITY INDICATORS FOR EFFULENT WASTE WATER

Dissolved oxygenThe dissolved oxygen (DO) is oxygen that is dissolved in water. The oxygen dissolves by diffusion from the surrounding air; aeration of water that has tumbled over falls and rapids; and as a waste product of photosynthesis. Fish and aquatic animals cannot split oxygen from water (H2O) or other oxygen-containing compounds. Only green plants and some bacteria can do that through photosynthesis and similar processes. Virtually all the oxygen we breath is manufactured by green plants. Effects of dissolved oxygen are Temperature effect: If water is too warm, there may not be enough oxygen in it. When there are too many bacteria or aquatic animal in the area, they may overpopulate, using DO in great amounts. If the weather becomes cloudy for several days, respiring plants will use much of the available DO. When these plants die, they become food for bacteria, which in turn multiply and use large amounts of oxygen. How much DO an aquatic organism needs depends upon its species, its physical state, water temperature, pollutants present, and more. Oxygen is more easily dissolved in cold water than in warm water and so organisms tend to thrive in cold water than warm water due to large quantity of dissolved oxygen.

Environmental effect: Total dissolved gas concentrations in water should not exceed 110 percent. Concentrations above this level can be harmful to aquatic life. Adequate dissolved oxygen is necessary for good water quality. As dissolved oxygen levels in water drop below 5.0 mg/l, aquatic life is put under stress. The lower the concentration, the greater the stress. Oxygen levels that remain below 1-2 mg/l for a few hours can result in large fish kills. Biologically speaking, however, the level of oxygen is a much more important measure of water quality than fecal coliform. Dissolved oxygen is absolutely essential for the survival of all aquatic organisms (not only fish but also invertebrates such as crabs, clams, zooplankton, etc). Moreover, oxygen affects a vast number of other water indicators, not only biochemical but esthetic ones like the odor, clarity and taste. Consequently, oxygen is perhaps the most well-established indicator of water quality. The main cause of a reduction of dissolved oxygen is the presence of organic matter. Flow rate: Oxygen concentrations vary with the volume and velocity of water flowing in a stream. Faster flowing white water areas tend to be more oxygen rich because more oxygen enters the water from the atmosphere in those areas than in slower, stagnant areas. Aquatic Plants: The presence of aquatic plants in a stream affects the dissolved oxygen concentration. Typical urban human activities may lower oxygen runoff and can result in decreased oxygen levels. Nutrient input often lead to excessive algal growth. When the algae die, the organic matter is decomposed by bacteria. Bacterial decomposition consumes a great deal of oxygen. Dams may pose an oxygen supply problem when they release waters from the bottom of their reservoirs into streams and rivers. Although the water on the bottom is cooler than the warm water on top, it may be low in oxygen if large amounts of organic matter has fallen to the bottom and has been decomposed by bacteria.

How Dissolved Oxygen Affects Water SuppliesA high DO level in a community water supply is good because it makes drinking water taste better. However, high DO levels speed up corrosion in water pipes. For this reason, industries use water with the least possible amount of dissolved oxygen. Water used in very low pressure boilers have no more than 2.0 ppm of DO, but most boiler plant operators try to keep oxygen levels to 0.007 ppm or less.

BIOLOGICAL OXYGEN DEMAND (BOD) is the amount of dissolved oxygen needed by aerobic biological organisms in a body of water to break down organic material present in a given water sample at certain temperature over a specific time period. The term also refers to a chemical procedure for determining this amount. This is not a precise quantitative test, although it is widely used as an indication of the organic quality of water. The BOD value is most commonly expressed in milligrams of oxygen consumed per litre of sample during 5 days of incubation at 20 C and is often used as a robust surrogate of the degree of organic pollution of water.The purpose of this indicator is to assess the quality of water available to consumers in localities or communities for basic and commercial needs and also to gauge the effectiveness of waste water treatment plant. It is also one of a group of indicators of ecosystem health.BOD is similar in function to chemical oxygen demand (COD), in that both measure the amount of organic compounds in water. However, COD is less specific, since it measures everything that can be chemically oxidized, rather than just levels of biologically active organic matter.

METHODOLOGICAL DESCRIPTION There are two main methods for measuring BOD: Method 1: This is the most common method used. It simply involves the incubation of a water sample over a specified period (usually five days) at a constant temperature of 20C in the dark. Method 2: This method involves the incubation of a water sample that is diluted with de-ionised water saturated with oxygen. The incubation of the diluted sample is identical to the first method, i.e., it is conducted over 5 days at a constant temperature of 20C in the dark. These tests represent standard laboratory procedures usually referred to as the BOD5 test. These procedures are used to estimate the relative oxygen consumption of wastewaters, effluents, and other waters affected by organic pollution. Microorganisms (mainly bacteria although other microorganisms, algae, plants and animals can also make significant contributions in some aquatic systems) use the oxygen in the water for oxidation of polluting organic matter and organic carbon produced by algae, plants and animals.

Measurement Methods: Method 1: This method consists of filling to overflowing an airtight bottle of specified size with the water sample to be tested. It is then incubated at a constant temperature for five days in the dark. Dissolved oxygen is measured initially and after incubation. The BOD5 is then computed from the difference between the initial and final readings of dissolved oxygen.

Method 2: This method consists of filling a bottle with incremental levels of a water sample that is then diluted with de-ionised water. The dilution water contains a known amount of dissolved oxygen. The bottles are completely filled, freed of air bubbles, sealed and allowed to stand for five days at a controlled temperature of 20 C (68 F) in the dark. During this period, bacteria oxidize the organic matter using the dissolved oxygen present in the water. At the end of the five-day period, the remaining dissolved oxygen is measured. The relationship of oxygen that was consumed during the five days and the volume of the sample increment are then used to calculate the BOD.Limitations of the Indicator: The main limitation of the indicator is that it provides empirical and not absolute results. It gives a good comparison among samples, but does not give an exact measure of the concentration of any particular contaminant. Further, it was designed to assess the impact of point-source organic effluents on source waters and is not generally suitable for environmental monitoring. Further, the BOD can increase due to an increase in nutrient (e.g., nitrogen and phosphorus) loads to a water body (eutrophication) without a concomitant increase in external organic carbon loading. The increase in nutrients stimulates the growth of algae and aquatic plants (primary production), which causes an indirect increase in biological (usually mainly bacterial) oxygen consumption. However, bacterial activity can be directly increased in some waters with low nutrient concentrations. The five-day time frame to obtain results represents the main operational drawback of the indicator. In addition, the methodologies outlined are not indicative of in situ oxygen consumption rates because of the artificial incubation conditions, i.e., bottling water with its associated microbial communities with no air flow, currents, light etc. Alternative Definitions/Indicators: Chemical Oxygen Demand (COD) is an alternative measure of the oxygen equivalent of the organic matter content of a sample that is susceptible to oxidation by a strong chemical exigent. COD can be empirically related to BOD5. After this correlation is determined for a specific source, it is a useful measure obtained from an instantaneous chemical test. Dissolved oxygen concentration (DO) is a better general environmental monitoring indicator that is also applicable to assessing organic pollution. DO also has known concentration limits for a variety of aquatic species. CHEMICAL OXYGEN DEMANDChemical oxygen demand (COD) test is commonly used to indirectly measure the amount of organic compounds in water. Most applications of COD determine the amount of organic pollutants found in surface water (e.g. lakes and rivers) or wastewater, making COD a useful measure of water quality. It is expressed in milligrams per liter (mg/L) also referred to as ppm (parts per million), which indicates the mass of oxygen consumed per liter of solution.It is the amount of oxygen consumed under specific conditions in the oxidation of organic and oxidation of inorganic compounds.TOTAL SOLIDSThe term "total solids" refers to matter suspended or dissolved in water or wastewater, and is related to both specific conductance and turbidity. Total solids (also referred to as total residue) is the term used for material left in a container after evaporation and drying of a water sample. Total Solids includes both total suspended solids, the portion of total solids retained by a filter (usually with a pore size of 0.45 micrometers), and total dissolved solids, the portion that passes through a filter (American Public Health Association, 1998).

TOTAL SUSPENDED SOLIDS (TSS)Total Suspended Solids (TSS) are solids in water that can be trapped by a filter. TSS can include a wide variety of material, such as silt, decaying plant and animal matter, industrial wastes, and sewage. High concentrations of suspended solids can cause many problems for stream health and aquatic life.High TSS can block light from reaching submerged vegetation. As the amount of light passing through the water is reduced, photosynthesis slows down. Reduced rates of photosynthesis causes less dissolved oxygen to be released into the water by plants. If light is completely blocked from bottom dwelling plants, the plants will stop producing oxygen and will die. As the plants are decomposed, bacteria will use up even more oxygen from the water. Low dissolved oxygen can lead to fish kills. High TSS can also cause an increase in surface water temperature, because the suspended particles absorb heat from sunlight. This can cause dissolved oxygen levels to fall even further (because warmer waters can hold less DO), and can harm aquatic life in many other ways, as discussed in the temperature section. The decrease in water clarity caused by TSS can affect the ability of fish to see and catch food. Suspended sediment can also clog fish gills, reduce growth rates, decrease resistance to disease, and prevent egg and larval development. When suspended solids settle to the bottom of a water body, they can smother the eggs of fish and aquatic insects, as well as suffocate newly hatched insect larvae. Settling sediments can fill in spaces between rocks which could have been used by aquatic organisms for homes.High TSS in a water body can often mean higher concentrations of bacteria, nutrients, pesticides, and metals in the water. These pollutants may attach to sediment particles on the land and be carried into water bodies with storm water. In the water, the pollutants may be released from the sediment or travel farther downstream (Federal Interagency Stream Restoration Working Group, 1998). High TSS can cause problems for industrial use, because the solids may clog or scour pipes and machinery.Measurement of Total Suspended SolidsTo measure TSS, the water sample is filtered through a pre-weighed filter. The residue retained on the filter is dried in an oven at 103 to 105 C until the weight of the filter no longer changes. The increase in weight of the filter represents the total suspended solids. TSS can also be measured by analyzing for total solids and subtracting total dissolved solids.Factors Affecting Total Suspended SolidsHigh Flow RatesThe flow rate of the water body is a primary factor in TSS concentrations. Fast running water can carry more particles and larger-sized sediment. Heavy rains can pick up sand, silt, clay, and organic particles (such as leaves, soil, and tire particles) from the land and carry it to surface water. A change in flow rate can also affect TSS; if the speed or direction of the water current increases, particulate matter from bottom sediments may be re-suspended.

Soil ErosionSoil erosion is caused by disturbance of a land surface. Soil erosion can be caused by Building and Road Construction, Forest Fires, Logging, and Mining. The eroded soil particles can be carried by storm water to surface water. This will increase the TSS of the water body.Urban RunoffDuring storm events, soil particles and debris from streets and industrial, commerical, and residential areas can be washed into streams. Because of the large amount of pavement in urban areas, infiltration is decreased, velocity increases, and natural settling areas have been removed. Sediment is carried through storm drains directly to creeks and rivers.Wastewater and Septic System EffluentThe effluent from Wastewater Treatment Plants (WWTPs) can add suspended solids to a stream. The wastewater from our houses contains food residue, human waste, and other solid material that we put down our drains. Most of the solids are removed from the water at the WWTP before being discharged to the stream, but treatment cant eliminate everything.Decaying Plants and AnimalsAs plants and animals decay, suspended organic particles are released and can contribute to the TSS concentration.Bottom-Feeding FishBottom-feeding fish (such as carp) can stir up sediments as they remove vegetation. These sediments can contribute to TSS.TOTAL DISSOLVED SOLIDS (TDS)Total Dissolved Solids (TDS) are solids in water that can pass through a filter. TDS is a measure of the amount of material dissolved in water. This material can include carbonate, bicarbonate, chloride, sulfate, phosphate, nitrate, calcium, magnesium, sodium, organic ions, and other ions. A certain level of these ions in water is necessary for aquatic life. Changes in TDS concentrations can be harmful because the density of the water determines the flow of water into and out of an organism's cells (Mitchell and Stapp, 1992). However, if TDS concentrations are too high or too low, the growth of many aquatic life can be limited, and death may occur. Similar to TSS, high concentrations of TDS may also reduce water clarity, contribute to a decrease in photosynthesis, combine with toxic compounds and heavy metals, and lead to an increase in water temperature. TDS is used to estimate the quality of drinking water, because it represents the amount of ions in the water. Water with high TDS often has a bad taste and/or high water hardness, and could result in a laxative effect.Measurement of Total Dissolved SolidsTo measure TDS, the water sample is filtered, and then the filtrate (the water that passes through the filter) is evaporated in a pre-weighed dish and dried in an oven at 180 C, until the weight of the dish no longer changes. The increase in weight of the dish represents the total dissolved solids, and is reported in milligrams per liter (mg/l). The TDS concentration of a water sample can be estimated from specific conductance if a linear correlation between the two parameters is first established. Depending on the chemistry of the water, TDS (in mg/l) can be estimated by multiplying specific conductance (in micromhos/cm) by a factor between 0.55 and 0.75. TDS can also be determined by measuring individual ions and adding them up.Factors Affecting Total Dissolved SolidsGeology and Soil in the WatershedSome rock and soil release ions very easily when water flows over them; for example, if acidic water flows over rocks containing calcite (CaCO3), such as calcareous shales, calcium (Ca2+) and carbonate (CO32-) ions will dissolve into the water. Therefore, TDS will increase. However, some rocks, such as quartz-rich granite, are very resistant to dissolution, and dont dissolve easily when water flows over them. TDS of waters draining areas where the geology only consists of granite or other resistant rocks will be low (unless other factors are involved).Urban RunoffDuring storm events, pollutants such as salts from streets, fertilizers from lawns, and other material can be washed into streams and rivers. Because of the large amount of pavement in urban areas, natural settling areas have been removed, and dissolved solids are carried through storm drains to creeks and rivers.

Fertilizer RunoffFertilizer can dissolve in stormwater and be carried to surface water during storms, and contribute to TDS.Wastewater and Septic System EffluentThe effluent from Wastewater Treatment Plants (WWTPs) adds dissolved solids to a stream. The wastewater from our houses contains both suspended and dissolved solids that we put down our drain. Most of the suspended solids are removed from the water at the WWTP before being discharged to the stream, but WWTPs only remove some of the TDS. Important components of the TDS load from WWTPs include phosphorus, nitrogen, and organic matter.Soil ErosionSoil erosion is caused by disturbance of a land surface. Soil erosion can be caused by Building and Road Construction, Forest Fires, Logging, and Mining. The eroded soil particles may contain soluble components that can dissolve and be carried by stormwater to surface water. This will increase the TDS of the water body.Decaying Plants and AnimalsAs plants and animals decay, dissolved organic particles are released and can contribute to the TDS concentration.Water Quality Standards Regarding Total Dissolved SolidsThe U.S. Environmental Protection Agency (U.S. EPA) sets a secondary standard of 500 mg/l TDS in drinking water Secondary standards are unenforceable, but recommended, guidelines for contaminants that may cause cosmetic or aesthetic effects in drinking water. High TDS concentrations can produce laxative effects and can give an unpleasant mineral taste to water. High TDS concentrations in water is also unsuitable for many industrial applications.ENVIRONMENTAL LEVELS AND HUMAN EXPOSUREWater SUPPLIESTDS in water supplies originate from natural sources, sewage, urban and agricultural run-off, and industrial wastewater. Salts used for road de-icing can also contribute to the TDS loading of water supplies.Concentrations of TDS from natural sources have been found to vary from less than 30 mg/litre to as much as 6000 mg/litre, depending on the solubilities of minerals in different geological regions.EFFECTS ON HUMANSNo recent data on health effects associated with the ingestion of TDS in drinking-water appear to exist; however, associations between various health effects and hardness, rather than TDS content, have been investigated in many studies. In early studies, inverse relationships were reported between TDS concentrations in drinking water and the incidence of cancer, coronary heart disease, arteriosclerotic heart disease, and cardiovascular disease. Total mortality rates were reported to be inversely correlated with TDS levels in drinking-water. No attempts were made to relate mortality from cardiovascular disease to other potential confounding factors.Certain components of TDS, such as chlorides, sulfates, magnesium, calcium, and carbonates, affect corrosion or encrustation in water-distribution systems. High TDS levels (>500 mg/litre) result in excessive scaling in water pipes, water heaters, boilers, and household appliances such as kettles and steam irons. Such scaling can shorten the service life of these appliances.The results of early epidemiological studies suggest that even low concentrations of TDS in drinking-water may have beneficial effects, although adverse effects have been reported in two limited investigations. Water containing TDS concentrations below 1000 mg/litre is usually acceptable to consumers, although acceptability may vary according to circumstances. However, the presence of high levels of TDS in water may be objectionable to consumers owing to the resulting taste and to excessive scaling in water pipes, heaters, boilers, and household appliances. Water with extremely low concentrations of TDS may also be unacceptable to consumers because of its flat, insipid taste; it is also often corrosive to water-supply systems.In areas where the TDS content of the water supply is very high, the individual constituents should be identified and the local public health authorities consulted. No health-based guideline value is proposed for TDS.TURBIDITYTurbidity is the cloudiness or haziness of a fluid caused by individual particles that are generally invisible to the naked eye. Fluids can contain suspended solid matter consisting of particles of many different sizes, while some suspended material will be large enough and heavy enough to settle rapidly of the bottom of the container. The unit for turbidity is Nephelometric turbidity units (NTU). However, higher levels of turbidity pose several problems for stream systems. Turbidity blocks out the light needed by submerged aquatic vegetation. It also can raise surface water temperatures above normal because suspended particles near the surface facilitate the absorption of heat from sunlight. Suspended soil particles may carry nutrients, pesticides, and other pollutants throughout a stream system, and they can bury eggs and benthic critters when they settle. Turbid waters may also be low in dissolved oxygen. High turbidity may result from sediment bearing runoff, or nutrients inputs that cause plankton blooms (1991, Streamkeeper's Field Guide: Watershed Inventory and Stream Monitoring Methods).

WASTE MANAGEMENT AND EFFLUENT TREATMENT- WHY?Environmental pollution continues to be one of the major problems of the world since man began industrialization, and this pollution continues to rise to critical levels in some certain countries. Inappropriately managed waste and effluents can attract rodents and insects, which can harbour gastrointestinal parasites, yellow fever, worms, the plague and other conditions for humans, and exposure to hazardous wastes, particularly when they are burned, can cause various other diseases including cancers. Toxic waste materials can contaminate surface water, groundwater, soil, and air which causes more problems for humans, other species, and ecosystems. Unless wastes from all sources and effluents are effectively managed and treated respectively, pollution level in the world will continue to rise exponentially without a halt

GROUP MEMBERSMATRIC NUMBERANINYEM MICHAEL CHUKSENG0902078OKORO BLESSING NNEKAENG0902130ADEDOYIN STANLEY KELLYENG0902066ENOWOGHOMWENMA EDOSAENG0902099AGHOGHOPHIA EBIPRIYEENG0902069AMINAH MARDIYYAH RUFAIENG0902145

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