Unit 3 POLLUTION FROM MAJOR INDUSTRIES P.MUTHURAMAN, V VCOE

Transcription

1 Unit 3 POLLUTION FROM MAJOR INDUSTRIES P.MUTHURAMAN, V VCOE

2 POLLUTION FROM MAJOR INDUSTRIES Sources, Characteristics, waste treatment flow sheets for selected industries such as Textiles, Tanneries, Pharmaceuticals, Electroplating industries, Dairy, Sugar, Paper, distilleries, Steel plants, Refineries, fertilizer, thermal power reclamation concepts. plants Wastewater

3 Textiles Industry

4 Textiles Industry Textile wastewater includes a large variety of dyes and chemical additions that make the environmental challenge for textile industry not only as liquid waste but also in its chemical composition. Main pollution in textile wastewater come from dyeing and finishing processes. These processes require the input of a wide range of chemicals and dyestuffs, which generally are organic compounds of complex structure.

5 Water is used as the principal medium to apply dyes and various chemicals for finishes. Because all of them are not contained in the final product, became waste and caused disposal problems. Major pollutants in textile wastewaters are high suspended solids, chemical oxygen demand, heat, colour, acidity, and other soluble substances. Substances which need to be removed from textile wastewater are mainly COD, BOD, nitrogen, heavy metals and dyestuffs1,2

6 Textile mill uses cotton, wool or synthetic fibers. Waste water generated depends upon type of fiber used. The pollutants in the wastewater include - The fibers used and - Chemicals used in processing

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19 Tannery Industry Industrial Waste Treatment

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35 Pharmaceutical Industry Waste Management System

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54 Diary Industry Waste Management System

55 Introduction The dairy industry involves processing raw milk into products such as consumer milk, butter, cheese, yogurt, condensed milk, dried milk (milk powder), and ice cream, using processes such as chilling, pasteurization, and homogenization. Typical by-products include buttermilk, whey, and their derivatives. Dairy industries have shown tremendous growth in size and number inmost countries of the world.

56 These industries characterized by discharge high wastewater chemical which oxygen is demand, biological oxygen demand, nutrients, and organic and inorganic contents. Such wastewaters, if discharged without proper treatment, severely pollute receiving water bodies.

57 DAIRY PROCESSING Dairy processing plants can be divided into two categories: Fluid milk processing involving the pasteurization and processing of raw milk into liquid milk for direct consumption, as well as cream, flavored milk, and fermented products such as buttermilk and yogurt. Industrial milk processing involving the pasteurization and processing of raw milk into value-added dairy products such as cheese and casein, butter and other milk fats, milk powder and condensed milk, whey powder and other dairy ingredients, and ice cream and other frozen dairy products.

58 Diary Processing Activities Raw Milk Collection, Reception and Storage Separation and Standardization Homogenization Heat Treatment and Cooling of Milk Products Milk and Dairy Product Production Milk production Cheese production Butter production Milk powder production Packaging of Milk and Dairy Products

59 Raw Milk Collection, Reception and Storage The first steps in preserving the quality of milk should be taken at the farm. To achieve the best quality raw milk at intake, milking conditions must be as hygienic as possible. The milk must be chilled to below + 4oC immediately after milking and be kept at this temperature during transport to the dairy. Raw milk is collected and transported to the processing plant in stainless steel

60 Separation and Standardization Centrifugal separation and clarification is common in dairy processing to ensure further processing of standard products avoiding quality variations. Standardization of the dry matter for fat, protein, and lactose content of the milk usually takes place in the production phase of most dairy products

61 Homogenization The aim of homogenization is to prevent gravity separation of the fat in the product and to improve the syneresis stability of mainly cultured products. The homogenizer consists of a high pressure pump and homogenizing valve driven by a powerful electric motor.

62 MILK PRODUCTION The processes taking place at a typical milk plant include: receipt and filtration/clarification of the raw milk; separation of all or part of the milk fat (for standardisation of market milk, production of cream and butter and other fat-based products, and production of milk powders); pasteurisation; homogenisation (if required); deodorisation (if required); further product-specific processing; packaging and storage, including cold storage for perishable products; distribution of final products

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64 BUTTER PRODUCTION The butter-making process, whether by batch or continuous methods, consists of the following steps: preparation of the cream; destabilisation and breakdown of the fat and water emulsion; aggregation and concentration of the fat particles; formation of a stable emulsion; packaging and storage;

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66 CHEESE PRODUCTION Virtually all cheese is made by coagulating milk protein (casein) in a manner that traps milk solids and milk fat into a curd matrix. This curd matrix is then consolidated to express the liquid fraction, cheese whey. Cheese whey contains those milk solids which are not held in the curd mass, in particular most of the milk sugar (lactose) and a number of soluble proteins.

67 CHEESE PRODUCTION Milk receipt, pre-treatment and standardisation Pasteurisation Addition of starter culture Coagulation Extraction of whey Cutting and cooking of curd Salting Ripening Packaging Distribution

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69 MILK POWDER PRODUCTION The milk is preheated in tubular heat exchangers before being dried. The preheated milk is fed to an evaporator to increase the concentration of total solids. The solids concentration that can be reached depends on the efficiency of the equipment and the amount of heat that can be applied without unduly degrading the milk protein. The milk concentrate is then pumped to the atomizer of a drying chamber.

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71 In the drying chamber the milk is dispersed as a fine foglike mist into a rapidly moving hot air stream, which causes the individual mist droplets to instantly evaporate. Milk powder falls to the bottom of the chamber, from where it is removed. Fine milk powder particles are carried out of the chamber along with the hot air stream and collected in cyclone separators.

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73 PACKAGING OF MILK AND DAIRY PRODUCTS

74 Packaging protects the product from bacteriological, light, and oxygen contamination. Liquid milk products may be packed in a beverage carton, which is mainly paperboard covered by a thin layer of foodgrade polyethylene on either side. Milk cartons for long-life milk have an additional layer of aluminum foil. Many other packaging materials are also used, ranging from simple plastic pouches to glass bottles, PET laminates and PVC bottles.

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76 WASTEWATER GENERATION The dairy industry is one of the most polluting of industries, not only in terms of the volume of effluent generated, but also in terms of its characteristics as well. A chain of operations involving receiving and storing of raw materials, processing of raw materials into finished products, packaging and storing of finished products, and a group of other ancillary operations (e.g., heat transfer and cleaning) will produce wastewater.

77 CHARACTERISTICS OF WASTEWATER Dairy wastewater contains milk solids, detergents, sanitizers, milk wastes, and cleaning water. It is characterized by high concentrations of nutrients, and organic and inorganic contents. Salting activities during cheese production may result in high salinity levels. Wastewater may also contain acids, alkali with a number of active ingredients, and disinfectants, as well as a significant microbiological load, pathogenic viruses, and bacteria. Other wastewater streams include cooling water from utilities, storm water, and sanitary sewage.

78 CHARACTERISTICS OF WASTEWATER

79 The dairy industry generate on an average litres of wastewater per litre of milk processed The effluents are generated from milk processing through milk spillage, drippings, washing of cans, tankers bottles, utensil, and equipment s and floors. Process in the treatment of industrial effluent may consist of any one or more of the following processes: 1. Equalization 2. Neutralization 3. Physical Treatment 4. Biological Treatment

80 EFFECTS WHEN WASTEWATER DISCHARGED TO LAND Dissolved salts contained in dairy plant wastewater can adversely affect soil structure if wastewater is used to irrigate land. Wastewater can also leach into underlying groundwater and affect its quality. High salt levels affect the type of vegetation that grow. Over-irrigation may cause the underlying water table to rise, resulting in further deterioration of surface soils and vegetation.

81 EFFECTS WHEN WASTEWATER DISCHARGED TO SEWER The volume and organic load of wastewater from just one dairy factory during peak season may well exceed the township's domestic waste. This may overload the sewage treatment plant, cause odors and give rise to poor effluent quality. Domestic wastewaters have a BOD5 concentration of about 250 to 300 mg/l but in peak season a large dairy factory could be discharging two mega liters of wastewater at BOD5 of 2,000 mg/l each day the additional load on a sewerage plant is equivalent to an extra 16,000 persons which is very difficult to treat.

82 AVOIDING WASTE DURING LIQUID MILK PRODUCTION Liquid milk may lead production to the generation of odour, wastewater, noise and solid waste. Suggestions for avoiding wastes during liquid milk production are given in Figure.

83 AVOIDING WASTE DURING BUTTER PRODUCTION Ways to prevent the build up of surface deposits include: minimisation of surface area prevention of build-up of milk stone deposits maintenance of butter churns correct preparation before filling not over-working the batch To avoid spills, buttermilk collection facilities should be large enough to hold all buttermilk discharged. Buttermilk should be dried or used as animal feed and solids recovered from butter wash water also may be sold as stock feed.

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85 AVOIDING WASTE DURING CHEESE PRODUCTION Making cheese generates a large volume of by-products such as whey. Waste reduction can be achieved by: not overfilling cheese vats to stop curd loss completely removing whey and curds from vats before rinsing segregating all whey drained from cheese sweeping up pressings (particles) screening all liquid streams to collect fines.

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87 AVOIDING WASTE DURING MILK POWDER PRODUCTION It is suggested that evaporators be operated to: maintain a liquid level low enough to stop product boilover run to specified length excessively long runs with higher than specified running rates lead to blocked tubes which not only produce high pollution, but are difficult and time consuming to clean use effluent entrainment separators to avoid carry-over of milk droplets during condensation of evaporated water minimize air emissions by using fabric filters or wet

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89 REUSE AND RECYCLE Many dairy plants have technologies in place for recovering wastewater and/or for reuse in the dairy plant. Reuse and recycling can considerably decrease the volume of mains water required to operate the plant. Reuse and recycling reduce the cost of both mains water and wastewater disposal. Fats, milk solids and minerals can also be recovered from wastewater and recycled either at the dairy plant or offsite. Cleaning chemicals can also be recovered and reused on site.

90 TREATMENT OF DAIRY EFFLUENT The highly variable nature of dairy wastewaters in terms of volumes and flow rates and in terms of ph and suspended solid (SS) content makes the choice of an effective wastewater treatment regime difficult. Because dairy wastewaters are highly biodegradable, they can be effectively treated with biological wastewater treatment systems, but can pose a potential environmental hazard if not treated properly.

91 TREATMENT OF DAIRY EFFLUENT

92 Sugar Industry

93 Sugar-Manufacturing Z:\IWM\Sugar Manufacturing Video.FLV.mp3

94 Sugar Industry Sugar can be produce from beet or from sugar cane. In India sugarcanes are used, Europe beet is used. The mills are typically operated for 4 to 8 months after the harvesting of sugar cane. Odour nuisance near the sugar mills is a very common phenomenon.

95 Manufacturing process Mill house: Sugar canes are cut into pieces and crushed in a series of rollers to extract the juice in the mill house. Lime Treatment The milk of lime is added to the juice and heated. When colloidal and suspended impurities are coagulated, most of colour is also removed during lime treatment. The coagulated juice is clarified to remove sludge. The sludge is further filtered through filter press and then disposed off as solid waste (press mud).

96 Sulphitation process The filtrate is recycled to process along with entire quantity of clarified juice. This juice is treated by passing sulphur dioxide gas through it. This is known as sulphitation process. Colour of juice is completely bleached out due to this process. The clarified juice is then preheated and concentrated in evaporators and vacuum pans. The partially crystallized syrup from vacuum pan known as massecuite is transferred to the crystallizers.

97 Crystallizers In crystallizers complete crystallization of sugar occurs. The massecuite is then centrifuged to separate the sugar crystals from liquor. The spent liquor is discarded as black strap molasses. Sugar is then dried and bagged for transport. The fibrous residue of the mill house, known as bagasses is burnt in the boilers or may be used as rawmaterials for paper products. Black strap molasses is used as raw material in distilleries.

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101 Sources of wastewater and characteristics The wastewater from mill house include the water used as splashes to extract maximum amount of juice and those used to cool the roller bearings. This wastewater contains high BOD due to presence of sugar and oil and grease from machineries. The wastewater from occasional washing of filter cloths (used for filtering the juice) though small in volume, contains high BOD and SS.

102 The water used for cooling in evaporators also contributes as wastewater. The cooling water gets polluted as it picks up some organic substances from the vapors of boiling syrup in evaporators and vacuum pan. Although this water is recirculated it is required to be discharged. This contributes to considerable volume of waste and moderate BOD.

103 Additional waste originates due to the leakages and spillages of juice, syrup and molasses in different sections, and also during handling of molasses. Washing of floor (periodic) contributes a lot to pollution load. Though, it is small in volume, strong in BOD concentration. Periodic blow-off of the boilers produce another intermittent waste discharge. This is high in SS, low in BOD and usually alkaline.

104 Characteristics of combined waste from sugar mill

105 Effect of the waste on receiving water The sugar mill effluent decomposes rapidly after few hours of stagnation. Rapid depletion of DO followed by anaerobic stabilization of waste causes a secondary pollution of offensive odour, black colour, and fish mortality. Usually situated in rural areas, hence no sewers are available for discharge.

106 Treatment of the wastes Pollution load in sugar mills can be reduced with better water and material economy practiced in plant. Recycling will reduce the volume of waste to great extent. e.g. volume of mill house waste can be reduced by recycling the water used for splashing. Dry floor cleaning and reducing quantity of floor wash water can reduce the volume of waste. Proper control of operation can reduce the g. overloading of evaporators and vacuum boiling of the syrup leads to loss of condenser water thus increase in volume effluent. pollution load e. pans, extensive sugar through and strength of

107 COD/BOD ratio (approx ) makes it biodegradable wastewater. Conventional aerobic treatment (ASP and TF) are not too efficient even at low organic loading rate. Due to seasonal nature of waste conventional treatment may not be economical. Anaerobic treatment (digestion and lagoon) can give > 70% to 90% efficiency. Effluent from anaerobic treatment can be treated by stabilization pond. Two stage biological treatments (anaerobic lagoon + stabilization pond) is common. Overall BOD > 90% can be removed. UASB reactor followed by waste stabilization pond is also effective

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110 Paper and Pulp Industry

111 Z:\IWM\The Paper Making Process.mp3

112 Z:\IWM\Paper and Pulp Industry.pdf

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114 DISTILLERIES

115 DISTILLERIES Distilleries are basically Alcohol producing Industries. Alcoholic industries uses different grains, Malted barley and Molasses as a raw material. According to the data of All India Distilleries 'Association About 1.6 Million kilolitres of alcohol are produced in India per year by 309 distilleries.

116 TYPES OF ALCOHOLIC INDUSTRY Depending on the type of raw material used Industries are classified as: 1. Beverage Alcoholic Industries: It uses Grains, Malted barley and Molasses as a raw material. 2. Industrial Alcoholic Industries: It uses Molasses as a raw material. Molasses generated during the manufacture of sugar from cane or beet. It is a waste product containing sugar, which can no longer be extracted economically.

117 MANUFACTURING PROCESS It includes Three stages: 1. Dilution: It involves dilution of the Molasses with water to 1220% sugar. 2. Acidification with sulphuric acid, Fermentation with the help of yeast, Saccharomyces,ceravisiae under controlled condition of ph & Temperature and Nutrient supplementation with Nitrogen and Phosphorus. 3. Multistage evaporation.

118 DISTILLERIES WASTE WATER Distilleries waste water is also known as Spent wash, Slop, Vinnasse, dunder. It is one of the most Obnoxious waste. It has high B.O.D, C.O.D, Dissolved solids and low ph It can be profitable subjected to anaerobic treatment to get gas(which has fuel value),followed by aerobic treatment to meet discharge standards. It is amenable to biological treatment.

119 The first column of the train removes the bulk of water and other constituent from the Ethanol and it is principal component of Spent wash. The other waste water stream come from fermenter washing, floor washing, cooling water, etc. It takes from 3 to 10 k.g of Molasses to produce 1 lt of alcohol and produce 10 to 15 lt. of spent wash. The total volume of waste water per litre of Alcohol produce ranges from 60 to 100 litres Cooling and Condenser waters are generally 6 times the volume of Spent wash and are generally not polluted, as they are use in surface condensers.

120 CHARACTERISTICS OF WASTE WATER IN MOLASSES DISTILLERY(GRAM PER LT.)

121 PRE-TREATMENT PROCESS Spent wash is highly polluted, It is essential to adopt measures such as : Recycling: It reduces the volume of waste water to be treated. Using in Irrigation: Spent wash, diluted 20times can be safely used for the irrigation of sugarcane. Evaporation: It is done to produce animal feed or fertilizers. Incineration: Incineration is done after evaporation, potash can be recovered from the ash.

122 EFFECTS OF DISCHARGE OF RAW SPENT WASH On Land: Pollution of ground water, charring of vegetation and crops, accumulation of salts and increase in Electrical conductivity of Soil. Into water: Lowering ph(of receving water),increase in Organic load, Depletion of dissolved Oxygen, Large scale fish kills, bad odors, discoloration of water.

123 TREATMENT OF WASTE WATER Treatment of Waste Water is most efficient by Biological process Physico-Chemical methods, Sedimentation(plain or Coagulants aid). It leads to Anaerobic conditions and odors nuisance. Treatment of Waste water is done by: 1. Anaerobic process 2. Aerobic process

124 ANAEROBIC PROCESS It includes: I. Fixed film bioreactors or non attached biomass reactor The composition of waste water for treatment by FFB is as:

125 Pilot Anaerobic Lagoon: Rectified sprit from distilleries waste water is treated by Pilot Anaerobic Lagoon. The composition of waste water for treatment by PAL is as:

126 The waste can be digested Anaerobically : Retention time =12 days(b.o.d Loading rate =11kg/metrecube/day) and 8days(6.12kg/metre cube/day). -> Gas production is 124 metre cube/kg BOD destroyed. Cow dung is used as a Seed material Stable condition were established in 60days. At Organic loading of 0.6 kg BOD/metre cube/day BOD reduction is 90-95% and Volatile solid reduction is 78%.

127 AEROBIC TREATMENT I. By Aerobic Cultivation of yeast on Spent wash It includes A Pure Culture of Saccharomyces cerevisiae is adapt to the Spent wash. It is possible to adapt the culture to100% waste water without addition of nutrients. The optimum ph was and optimum inoculum dose between 85 and 100 mg of dry yeast/70 ml of the waste. Total sugar and BOD reduction is reduced up to 60% &57.5%. In order to improve reduction Evaporation and Drying process can be used.

128 II. Wet Air Oxidation: Aim reduce the COD of the effluent to produce Acetic Acid. Acetic Acid is also a value added product. Process is done in the range of following parameters:

129 It is seen that Colour destruction is 95%. C0D reduction is 65%. Acetic acid is formed which can be recovered by Conventional methods of Extraction.

130 REFINERY - INDUSTRY WASTE MANAGEMENT

131 Z:\IWM\Refinery Waste Treatment.pdf

132 FERTILIZER - INDUSTRY WASTE MANAGEMENT

133 Z:\IWM\Fertilizer Industry.pdf

134 STEEL - INDUSTRY WASTE MANAGEMENT