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IH682 HAZARDOUS WASTE MANAGEMENT Credits 4 (L = 4, P = 0) SCHEME OF TEACHING. TOPICS & SUBTOPICS N01Introduction to waste, definitions, types, characteristic, physical and chemical property. Sampling, method, preservation of liquid waste sample BOD, COD, ThoD, TOC, TOD and Bioassay test
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IH682 HAZARDOUS WASTE MANAGEMENT Credits 4 (L = 4, P = 0) SCHEME OF TEACHING
TOPICS & SUBTOPICS • N01Introduction to waste, definitions, types, characteristic, physical and chemical property. • Sampling, method, preservation of liquid waste sample • BOD, COD, ThoD, TOC, TOD and Bioassay test • Effluent treatment for domestic waste, ET for Industrial waste in a detail, functions of different pathways, limitation, problems and its solutions • Difference between industrial and municipal waste, environmental impact of industrial waste. • Chlorine, ozone, UV treatment of waste. • Neutralization of waste
Waste any materials unused and rejected as worthless or unwanted; sewage - waste matter carried away in sewers or drains or Sewage is water-carried waste, in solution or suspension, that is intended to be removed from a community. Also known as wastewater, it is more than 99% water and is characterized by volume or rate of flow, physical condition, chemical constituents and the bacteriological organisms that it contains waste matter from domestic or industrial establishments that is carried away in sewers or drains for dumping or conversion into a form that is not toxic Old French assewer, derived from the Latin exaquare, "to drain out (water)“ The term "wastewater" is a broad, descriptive term. Generally it includes liquids and waterborne solids from domestic, industrial or commercial uses as well as other waters that have been used (or "fouled") in man's activities, whose quality has been degraded, and which are discharged to a sewage system. The term "sewage" has been used for many years and generally refers to waters containing only sanitary wastes. However, "sewage" technically denotes any wastewaters which pass through a sewer. . Domestic wastewaters originate principally from domestic, household activities but will usually include waters discharged from commercial and business buildings and institutions as well as ground water. Surface and storm waters may also be present. Domestic wastewaters are usually of a predictable quality and quantity. Sources and Types of Wastewater Domestic wastewaters consist primarily of liquid discharges resulting from sanitary facilities, bathing, laundering and cooking activities as well as from other sources.
Industrial Wastewaters Industrial wastewaters are the discharges of industrial plants and manufacturing processes. Industrial wastewaters can represent, collectively, an important part of community wastewaters and must be considered for successful wastewater treatment plant operation. In some locations industrial wastewater discharges are collected together with other community wastewaters and the mixed wastes are treated together. In other instances, the industry may provide some pretreatment or partial treatment of its wastewaters prior to discharge to the municipal sewers. In still other situations, the volume and character of the industrial waste is such that separate collection and disposal is necessary. Industrial wastewaters vary widely in composition, strength, flow and volume, depending on the specific industry or manufacturing establishment in the community. Typical industries which produce significant volumes of wastewaters include paper and fiber plants, steel mills, refining and petrochemical operations, chemical and fertilizer plants, meat packers and poultry processors, vegetable and fruit packing operations and many more. Industrial discharges may consist of very strong organic wastewaters with a high oxygen demand, or contain undesirable chemicals which can damage sewers and other structures. They may contain compounds which resist biological degradation or toxic components which interfere with satisfactory operation of the wastewater treatment plant. A less obvious source which must be considered an industrial waste, is thermal discharge since it lowers dissolved oxygen values. Many industries use large quantities of cooling water, with the electric power industry being the largest user. However, the primary metal and chemical industry also use substantial quantities of cooling waters.
CHARACTRISTICS OF WASTE WATERS /SEWAGE An understanding of physical, chemical, and biological characteristics of wastewater is very important in design, operation, and management of collection, treatment, and disposal of wastewater. The nature of wastewater includes physical, chemical, and biological characteristics which depend on the water usage in the community, the industrial and commercial contributions, weather, and infiltration/inflow.
Sampling of Wastewaters . The object of sampling is to collect a portion of wastewater small enough in volume to be conveniently handled in the laboratory and still representative of the wastewater to be examined. REPRESENTATIVE SAMPLING A sample should be taken in a way that will represent the wastewater being treated. No matter how good the lab analysis is, if the sample was not correctly collected, the lab data will not be correct. With the large changes in composition and flow rate, getting a represen- tative sample can be very hard. Careful thought, planning, and training must be used to develop and carry out a good sampling program. It must be collected in such a manner that nothing is added or lost in the portion taken and no change occurs during the time between collection and laboratory examination. Unless these conditions are met, laboratory results may be misleading and worse than no results.
The sample should be taken where the wastewater is well mixed. This is most easily accomplished if the sampling point is located where the wastewater flow is turbulent, for example, at a tap on the discharge side of a pump, where a free fall from a pipe line occurs, where the discharge from a pipe is against a baffle as at the inlet of a tank, or just as the flow enters a pipe as at the effluent line from a tank. Large particles should be excluded. Large particles are all those greater than one-quarter inch in diameter. This is reasonable because if one large piece was included in a one-gallon sample, it would mean that wastewater would contain one million large pieces per million gallons of wastewater. Raw wastewater should be sampled after screening where screens or comminutors are used. No deposits, growths or floating material that have accumulated at the sampling point should be included. Obviously, such material would not be representative of the wastewater. This may be difficult if sampling is at a manhole, but it can be done if care is used. Samples should be examined as soon as possible. If held for more than one hour, they should be cooled by immersion of the sample bottle in ice water. Bacterial decomposition of wastewater continues in the sample bottle. After one hour, the changes due to such decomposition are appreciable. Cooling the sample greatly retards bacterial action. The collection of proper samples should be made as easy as possible. Sampling points should be readily accessible, proper equipment should be at hand, safety precautions established, and protection of personnel from inclement weather provided, for the easier it is to take proper samples, the more likely it will be done. Sample preservation may be necessary for some chemical constituents.
There are two types of samples that may be collected, depending on the time available, the tests to be made and the object of the tests. Catch or Grab Samples Catch or grab samples are not representative of the average wastewater since they reflect only the condition at the instant of sampling. However, in many plants the time available for sampling is so limited that catch samples must be used. Composite Samples Composite samples indicate the character of the wastewater over a period of time. The effects of intermittent changes in strength and flow are eliminated. The portion used should be collected with sufficient frequency to obtain average results. If the strength and flow do not fluctuate rapidly, hourly portions over a 12 hour period are satisfactory. If the fluctuations are rapid, half-hourly or quarter-hourly samples may be required. The period of sampling may be varied covering four, eight or twelve hours, depending on the personnel available, the use to be made of the results, and effluent monitoring requirements. Generally, integrated samples are used to determine the character of the wastewater to be treated and the efficiency of the treatment units.
Equipment An aluminum dipper six inches in diameter and approximately four inches deep with a long handle is convenient for collecting wastewater from tanks and channels. For sampling from manholes a one-quart pail which can be fastened to a wooden pole with a harness snap is used. Graduated cylinders, sample bottles, and some means of refrigeration are also needed. Special technique is required for collecting samples for dissolved oxygen and for bacteriological examination.
Preservation Once a sample is taken, the constituents of the sample should be maintained in the same condition as when collected. When it is not possible to analyze collected samples immediately, samples should be preserved properly. Biological activity such as microbial respiration, chemical activity such as precipitation or pH change, and physical activity such as aeration or high temperature must be kept to a minimum. Methods of preservation include cooling, pH control, and chemical addition. Freezing is usually not recommended. The length of time that a constituent in wastewater will remain stable is related to the character of the constituent and the preservation method used.
Grab sample volumes of one litre are recommended. The larger the volume of sewage analysed the higher the theoretical sensitivity to detect poliovirus circulation in the source population. In practice volumes larger than 1 litre are difficult to handle in the laboratory and may be replaced by several parallel regular samples.
Composition of Wastewater Wastewaters consist of water in which solids exist as settleable particles, dispersed as colloids, which are materials that do not settle readily, or solids in a dissolved state. The wastewater mixture will contain large numbers of microscopic organisms, mostly bacteria, that are capable of consuming the organic component (fats, proteins and carbohydrates) of the mixture and bringing about rapid changes in the wastewater. Since the sources of wastewater as well as the inputs are highly variable and since there is also an active microbial component, the composition of all wastewaters is constantly changing.. The solid components of wastewaters actually represents a very small part of most discharges, usually less than 0.1 percent by weight.
CHARACTERISTICS OF SEWAGE Sewage is composed of many materials that are broken down into three general areas. These areas are the physical, chemical, and biological characteristics of wastewater PHYSICAL CHARACTERISTICS The physical characteristics of wastewater include those items that can be detected using the physical senses. They are temperature, color, odor, and solids CHEMICAL CHARACTERISTICS The chemical characteristics of wastewater of special concern to the Utilities main are pH, DO (dissolved oxygen), oxygen demand, nutrients, and toxic substances BIOLOGICAL CHARACTERISTICS The three biological organisms present in wastewater are bacteria, viruses, and parasites. Typically, a domestic wastewater will contain from 100,000 to 1,000,000 microorganisms per milliliter. These microbes have their origin from two general sources: sanitary wastes and the soil. Both wastewaters and soils contain large numbers of microorganisms -- especially bacteria. Generally the microorganisms can be regarded as a natural living part of the organic matter found in wastewaters and their presence is most important because they serve a primary function in the degradation of wastes in biological wastewater treatment.
Physical Characteristics • Solids - Total solids: residue after evaporating all water (50% volatile and 50% fixed) (Volatile=organic. Fixed=inorganic mg/L) - Suspended solids: residue retained on a filter (75% volatile and 25% fixed). - Dissolved solids: residue passing through a filter (40% volatile and 60% fixed). - Settleable solids: residue after one hour settling in an Imhoff cone (ml/L) (the indicator of primary sludge).
Chemical Characteristics • Organics: Predominant biodegradable fraction, BOD -Protein -Fats, Oils, and Greases -Carbohydrates -Surfactants (detergents) -Urea • Priority pollutants • Industrial solvents, pesticides, etc. • Pre-treatment standards control concentrations to trace levels
Chemical Characteristics cont. • Inorganic Matter • Nitrogen: from protein and urea. NH2, NH3, NH4+ forms ammonia and organics. An essential nutrient for growth of bacteria. • Oxygen Demand: NH4+ + 2O2 = NO3- + 2 H+ + H2O
Chemical Characteristics cont. • Phosphorous: phosphate (PO4-3) • Inorganic-detergents • organic-food and metabolic wastes • Trace nutrients: S, Fe, Mn, Mg, Ca, K, Zn, Mo, etc. . . . . . plentiful
8.1 Composition of waste Composition of waste Waste from industrialized countries Characteristics: high content of packaging made of paper, plastic, glass and metal Moisture Content: Low Density: Low Waste from developing countries Characteristics: large amounts of inerts such as sand, ash, dust and stones and high moisture levels because of the high usage of fresh fruit and vegetables. Moisture Content: High Density: High
8.2 Municipal Vs Industrial Municipal Vs Industrial • Municipal waste includes: • - bulky waste (e.g. white goods, old furniture, mattresses); • - yard waste, leaves, grass clippings, street sweepings, the content of litter containers. • - market cleansing waste, if managed as waste • It includes waste originating from: • - households • - commerce and trade, small businesses, office buildings and institutions (schools, hospitals, government buildings)
Wastewater Characteristics • Wastewater Composition • Key design issues: • Solids: density, particle size, level of Volatile Suspended Solids • Biochemical Oxygen Demand • Temperature • Ammonia • Nutrient levels
Oxygen Demand It is the amount of oxygen used by bacteria and other wastewater organisms as they feed upon the organic solids in the wastewater. BOD BOD is defined as the amount of oxygen required by the bacteria while stabilizing decomposable organic matter under aerobic condition. It is written as by BOD or BOD520. “It is the amount of oxygen required by aerobic bacteria to decompose/stabilized the organic matter at a standard temperature of 20oC for a period of 05 days”. For domestic sewage 05 days BOD represents approx. 2/3 times of demand for complete decomposition. COD By definition the COD is the amount of oxygen required to stabilized the organic matter chemically, i.e. the COD is used as a measure of the oxygen equivalent of the organic matter contents of a sample that is susceptible to oxidation by a strong chemical oxidant.
Biochemical oxygen demand or B.O.D. 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. Carbonaceous biochemical oxygen demand or CBOD is a method defined test measured by the depletion of dissolved oxygen by biological organisms in a body of water in which the contribution from nitrogenous bacteria has been suppressed. CBOD is a method defined parameter is widely used as an indication of the pollutant removal from wastewater.
Biochemical Oxygen Demand, or BOD The amount of organic material that can rot in the sewage is measured by the biochemical oxygen demand. BOD is the amount of oxygen required by micro-organisms to decompose the organic substances in sewage. Therefore, the more organic material there is in the sewage, the higher the BOD. It is among the most important parameters for the design and operation of sewage treatment plants. BOD levels of industrial sewage may be many times that of domestic sewage. Dissolved oxygen is an important factor that determines the quality of water in lakes and rivers. The higher the concentration of dissolved oxygen, the better the water quality. When sewage enters a lake or stream, micro-organisms begin to decompose the organic materials. Oxygen is consumed as micro-organisms use it in their metabolism. This can quickly deplete the available oxygen in the water. When the dissolved oxygen levels drop too low, many aquatic species perish. In fact, if the oxygen level drops to zero, the water will become septic. When organic compounds decompose without oxygen, it gives rise to the undesirable odours usually associated with septic or putrid conditions.
Typical BOD5 (mg/L) Meat packing waste 5,000 Domestic wastewater 300 Wastewater treatment plant effluent <30 mg/L BOD5 Experiment -Typical DO Curves
Theoretical Oxygen Demand (ThOD) is the calculated amount of oxygen required to oxidize a compound to its final oxidation products. However, there are some differences between standard methods that can influence the results obtained: for example, some calculations assume that nitrogen released from organic compounds is generated as ammonia, whereas others allow for ammonia oxidation to nitrate. Therefore in expressing results, the calculation assumptions should always be stated. • In order to determine the ThOD for glycine (CH2(NH2)COOH) using the following assumptions: • In the first step, the organic carbon and nitrogen are converted to carbon dioxide (CO2) and ammonia (NH3), respectively. • 2. In the second and third steps, the ammonia is oxidized sequentially to nitrite and nitrate. • 3. The ThOD is the sum of the oxygen required for all three steps.
chemical 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. • The basis for the COD test is that nearly all organic compounds can be fully oxidized to carbon dioxide with a strong oxidizing agent under acidic conditions. The amount of oxygen required to oxidize an organic compound to carbon dioxide, ammonia, and water is given by: This expression does not include the oxygen demand caused by the oxidation of ammonia into nitrate. The process of ammonia being converted into nitrate is referred to as nitrification. The following is the correct equation for the oxidation of ammonia into nitrate
Bioassay testThe term 'bioassay' as it applies to the area of Earth observation can be defined as ' A measurement of the effects of a substance on living organisms'. The BOD test serves an important function in stream pollution-control activities. It is a bioassay procedure that measures the amount of oxygen consumed by living organisms while they are utilizing the organic matter present in waste, under conditions similar in nature. For results of the BOD test to be accurate, much care must be taken in the actual process. For example, additional air cannot be introduced. Temperature must be 20°C, which is the usual temperature of bodies of water in nature. A five-day BOD test is used in environmental monitoring. This test is utilized as a means of stating what level of contamination from pollutants is entering a body of water. In other words, this test measures the oxygen requirements of the bacteria and other organisms as they feed upon and bring about the decomposition of organic matter. Time and temperature, as well as plant life in the water, will have an effect on the test. High BOD burdens or loads are added to wastewater by food processing plants, dairy plants, canneries, distilleries and similar operations, and they are discharged into streams and other bodies of water
Unit Operations/Processes, Their Functions and Units Used for Domestic Wastewater Treatment
The benefits of waste minimisation are both environmental and financial and wide in their • coverage. Some of the main benefits include the following: • improved bottom line through improved process efficiency • reduced burden on the environment, with improved public image and compliance with legislation • better communication and involvement of employees and therefore greater commitment to the business
Back up Of hw • Topic No3 of MIHS Hazardous waste management • Back up collected by Prof.J.H.Patel BVM October2010 • ,
Topic No3 Hazardous Waste Management(6 lectures 10 marks ) 3.1 Definitions: Types EPA,RCRA,CERCLA , INTERNATIONAL Act for hazardous waste, Environmental Impact Assessment 3.2 Cradle to grave approach, Priority in Hazardous Waste management, Superfund Amendment and Reauthorization Act 1986, Dose Response Relationship, Effect of Hazardous waste on Aquatic System and how do they enter the food chains routes of entry ,fate of toxicants in body