ETP MANUAL STD

OPERATION & MAINTENANCE MANUAL FOR

EFFLUENT TREATMENT PLANT (Capacity = 30 M3/Hr.) INSTALLED AT

XYZ INDUSTRIES LTD.

BY AQUATECH ENGINEERING SERVICES LTD.

Aquatech Engineering Services Limited

GLOSSARY OF TERMS Biochemical Oxygen demand (BOD): The strength of the wastewater is often determined by measuring the amount of oxygen consumed by microorganism like bacteria in biodegrading the organic matter. The measurement is known as the Biochemical Oxygen Demand (BOD). Microorganisms such as bacteria are responsible for decomposing organic waste. When organic matter such as dead plants, leaves, grass clippings, cellulose components, manure, sewage, organic waste like dyes, fats and oils, or even food waste is present in a water supply, the bacteria will begin the process of breaking down this waste. When this happens, bacteria in aerobic process, robbing other aquatic organisms of the oxygen they need to live, consume much of the available dissolved oxygen. If there is a large quantity of organic waste in the water supply, there will also be a lot of bacteria present working to decompose this waste. In this case, the demand for oxygen will be high (due to all the bacteria) so the BOD level will be high. As the waste is consumed or dispersed through the water, BOD levels will begin to decline. Nitrogen and phosphates in a body of water can also contribute to high BOD levels. Nitrates and phosphates are plant nutrients and can cause plant life and algae to grow quickly. When plants grow quickly, they also die quickly. This contributes to the organic waste in the water, which is then decomposed by bacteria. This results in a high BOD level. The temperature of the water can also contribute to high BOD levels. For example, warmer water usually will have a higher BOD level than colder water. As water temperature increases, the rate of photosynthesis by algae and other plant life in the water also increases. When this happens, plants grow faster and also die faster. When the plants die, they fall to the bottom where they are decomposed by bacteria. The bacteria require oxygen for this process so the BOD is high at this location. Therefore, increased water temperatures will speed up bacterial decomposition and result in higher BOD levels. When BOD levels are high, dissolved oxygen (DO) levels decrease because the bacteria are consuming the oxygen that is available in the water. Since less dissolved oxygen is available in the water, fish and other aquatic organisms may not survive. Textile mill wastewater possesses a very high BOD like 400 – 600 mg/l. It is necessary to reduce this BOD value up to a level less than 30 mg/l before discharging them into the environment like canals or rivers. If a water body of high BOD is discharged into the sea or very large river then off course the concentration of BOD decreases due to dilution and have little or no harmful effect on the aquatic life or environment. Therefore if it is possible to discharge a highly toxic effluent in sea or large river no treatment is necessary. Though it was not mentioned, the dissolved oxygen (DO) is a highly significant parameter to define the BOD or COD of a wastewater. The amount of oxygen present in a certain amount of water in dissolved state is known as DO. It is normally expressed as mg/l. Water may contain DO ranging from 0 to 18 mg/l but in most cases of normal waters, DO lies between 7-9 mg/l. Aquatic lives require certain level of DO to survive in the water. In case of wastewater the microorganisms require oxygen to consume the organic wastes. As a result the DO of water decreases tremendously and becomes a threat to the life of aquatic species. Textile effluents possess very low 2


DO, which is unsuitable for discharging to the environment. During treatment of wastewater air is blown through the effluent when oxygen is dissolved in the effluent as a result DO level raises and as the DO increases the BOD/COD decreases. Chemical Oxygen Demand (COD): This is a means of measuring the ability of wastewater to sustain aquatic life, essential for the preservation of the environment. It also enables proper assessment of treatment plant performance. Aquatic organisms and animals require dissolved oxygen to flourish. The Chemical Oxygen Demand (COD) test gives an indication of the impact of discharge waters on aquatic life by measuring the oxygen depleting nature of the discharge water. COD is based on the fact that nearly all-organic compounds can be fully oxidized to carbon dioxide with a strong oxidizing agent under acidic condition. COD is another common measure of water-borne organic substances — the process of measuring COD causes the conversion of all organic matter into carbon dioxide. For this reason, one limitation of COD is that it cannot differentiate between biologically active and those which biologically inactive. One major advantage of COD over BOD is that COD can be measured in just three hours where as BOD measurement takes at least five days. The value of COD is always higher than BOD, this is because BOD accounts for only biodegradable organic compounds while COD accounts for all organic compounds e.g. biodegradable as well as no biodegradable but chemically oxidisable. Total suspended Solids (TSS): TSS is mainly organic in nature, are visible and can be removed from the wastewater by physical/ mechanical means e.g. screening and sedimentation. TSS is measured by filtering a certain quantity of effluent and then drying the filtrate at certain temperature e.g. 1050C followed by weighing. TSS is expressed as parts per million or in milligram/litre. The pore size of the filter paper is very important in estimating the TSS, the nominal pore size 1.58 micro metre. Total Dissolved Solids (TDS): TDS are the solids that are actually in solution, similar for example to mix sugar into hot coffee. Dissolved solids generally pass through the system unaffected. TDS is the sum total of all of the dissolved things in a given body of water. It is everything in the water that's not actually water. It includes hardness, alkalinity, cyanuric acid, chlorides, bromides, sulfates, silicates, and all manner of organic compounds. Every time we add anything to the water, we are increasing its TDS. This includes not only sanitizing and pH adjusting chemicals, but also conditioner, algaecides, and tile and surface cleaners. TDS also includes airborne pollutants and bather waste as well as dissolved minerals in the fill water. TDS is referred to as the total amount of mobile charged ions, including minerals, salts or metals dissolved in a given volume of water, and is expressed in units of mg per unit volume of water (mg/L), or as parts per million (ppm). Where do Dissolved Solids come from? Some dissolved solids come from organic sources such as leaves, silt, plankton, and dyes and chemicals used in processing, sewage. Other sources come from runoff from urban areas, road salts used on street during the winter, and fertilizers and pesticides used on lawns and farms.

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Dissolved solids also come from inorganic materials such as rocks and air that may contain calcium bicarbonate, nitrogen, iron phosphorous, sulfur, and other minerals. Many of these materials form salts, which are compounds that contain both a metal and a nonmetal. Salts usually dissolve in water forming ions. Ions are particles that have a positive or negative charge. Water may also pick up metals such as lead or copper as they travel through pipes used to distribute water to consumers. The effectiveness of water purification systems in removing total dissolved solids will be reduced over time, so it is highly recommended to monitor the quality of a filter or membrane and replace them when required. TDS may be the most misunderstood factor in the whole field of chemical processing and public health. In most cases it is misunderstood because no one knows exactly what effect it is going to have on any particular body of water. TDS is directly related to the purity of water and the quality of water purification systems and affects everything that consumes, lives in, or uses water, whether organic or inorganic, whether for better or for worse. Different standards advise a maximum contamination level (MCL) of 500mg/liter (500 parts per million (ppm)) for TDS, however for domestic water suppliers maintain the TDS within 150 ppm. Off course some water supplies exceed this level. When TDS levels exceed 1000mg/L it is generally considered unfit for human consumption. Most often, high levels of TDS are caused by the presence of potassium, chlorides and sodium. These ions have little or no short-term effects, but toxic ions (lead arsenic, cadmium, nitrate and others) may also be dissolved in the water. At low levels, TDS does not present a problem. In fact, a certain amount of TDS is necessary for water balance. Hardness and Total Alkalinity are both part of TDS. For textile processing the acceptable value of TDS is around 65-150 mg/l. The standards for bath and swimming pool are between 1,000 and 2,000 ppm, with a maximum of 3,000 ppm. For irrigation the acceptable values of TDS are around 1500 ppm. Use of fertilizers increases TDS of the environment. When the water evaporates, it leaves behind all of the solids that had been dissolved in it. This principle is used widely to measure the TDS of a particular body of water. When everything else seems to be all right, and the water still acts unlawfully, check the TDS. High TDS can result in corrosion of metal equipment and accessories, even though the water is balanced. High TDS can cause eye and skin irritation, even though the pH is right and there are no chloramines in the water. High TDS can permit an algae bloom, even with 2-3 ppm chlorine residual. If we drink water of high TDS some of this will stay in the body, causing stiffness in the joints, hardening of the arteries, kidney stones, gall stones and blockages of arteries, microscopic capillaries and other passages in which liquids flow through our entire body.

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Microorganisms - Microscopic living objects, which require energy, carbon and small amounts of inorganic elements to grow and multiply. They get these requirements from the wastewater and the sun, and in doing so help to remove the pollutants. pH – A term used to express the intensity of the acid or alkalinity source. pH represents the effective concentration (activity) of hydrogen ions (H+) in water. This concentration could be expressed in the same kind of units as other dissolved species, but H+ concentrations are much smaller than other species in most waters. The activity of hydrogen ions can be expressed most conveniently in logarithmic units. pH is defined as the negative logarithm of the activity of H+ ions: pH = -log [H+] where [H+] is the concentration of H+ ions in moles per liter (a mole is a unit of measurement, equal to 6.022 x 1023 atoms). Because H+ ions associate with water molecules to form hydronium (H3O+) ions, pH is often expressed in terms of the concentration of hydronium ions. In pure water at 22 C (72 F), H3O+ and hydroxyl (OH-) ions exist in equal quantities; the concentration of each is 1.0 x 10-7 moles per liter (mol/L). Therefore, pH of pure water = -log (1.0 x 10-7) = -(-7.00) = 7.00. Because pH is defined as –log [H+], pH decreases as [H+] increases (which will happen if acid is added to the water). Since pH is a log scale based on 10, the pH changes by 1 for every power of 10 changes in [H+]. A solution of pH 3 has an H+ concentration 10 times that of a solution of pH 4. The pH scale ranges from 0 to 14. However, pH values less than 0 and greater than 14 have been observed in very rare concentrated solutions. The U.S. Environmental Protection Agency (U.S. EPA) sets a secondary standard for pH levels in drinking water: the water should be between pH 6.5 and 8.5. Very high (greater than 9.5) or very low (less than 4.5) pH values are unsuitable for most aquatic organisms. Young fish and immature stages of aquatic insects are extremely sensitive to pH levels below 5 and may die at these low pH values. High pH levels (9-14) can harm fish by denaturing cellular membranes. Changes in pH can also affect aquatic life indirectly by altering other aspects of water chemistry. Low pH levels accelerate the release of metals from rocks or sediments in the stream. These metals can affect a fish’s metabolism and the fish’s ability to take water in through the gills, and can kill fish fry. The term "pH" was originally derived from the French term "pouvoir hydrogène," in English, this means "hydrogen power." The term pH is always written with a lower case p and an upper case H. Sludge-The settable solids separated from the liquid during sedimentation (clarification). The sludge is very toxic in nature and needs to be dealt with very carefully. Under no circumstances it should be mix with the environment again.

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1. INTRODUCTION Aquatech Engineering Services, Dhaka, have prepared this operating and maintenance manual for the Effluent treatment plant installed at ……………………., Chandora, Kaliakoir, Gazipur. It represents the methodology of process operation of the effluent treatment plant and maintenance of the plant equipments. The manual will be helpful to run the effluent plant effectively and efficiently. Every effluent treatment plant is unique with respect to its process flow sheet. This is because the treatment scheme is adopted on the basis of design and input characteristics of the effluent as well as the stipulated pollution level of the treatment. This in turn depends on the type of process, type of generated waste, whether the treated waste will be discharged or recycled, the nature of water receiving body where the treated waste will be discharged (if any) and the pollution laws of the concerned pollution authority. It must therefore be appreciated that effluent treatment plants are tailor- made, and hence the mode of operation would be specific for the treatment envisaged. The operating manual serves as an important guideline for the operating personnel responsible for the start- up and maintenance of the equipment and facilities provided in the plant. The instruction presents in this manual are based on the experience in operation of such plants. However, due to variable nature of the effluents encountered in each plant, certain modification of process operation may be necessary depending on the degree of variation in the raw effluent quality and quantity. This manual includes a brief description of the basis of design of the ETP, the adopted treatment philosophy and the principles of treatment involved. The plant was designed to treat effluents generated from the various sections of the knit fabric dyeing and finishing plant. The scheme envisages treatment of two separate wastewater streams namely the less contaminated water and more contaminated water. The less contaminated effluents are allowed to bypass many stages before uniting together again with mainstream and finally discharged to the environment. This has been done deliberately to reduce the treatment time and operating cost.

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2. Basics of effluent treatment Environmental problems of the textile industry are mainly caused by discharges of wastewater. Textile processing employs a variety of chemicals, depending on the nature of the raw material and end product. Some of these chemicals are different enzymes, detergents, dyes, acids, sodas and salts. Industrial processes generate wastewater containing heavy metal contaminants. Since most of the heavy metals are non-degradable into non-toxic end products, their concentrations must be reduced to acceptable levels before discharging them into the environment. Other wise these could pose threats to public health and/or affect the aesthetic quality of portable water. According to World Health Organization (WHO) the metals of most immediate concern are chromium, zinc, iron, mercury and lead. Various types of treatment processes are adopted to dye or print or finish the textile materials. Different types of textile process could generate different types of effluent. Table 1.1 shows the Characteristics of wastewater produced by a typical knit dyeing industry. Table 1.1: Characteristics of Process Waste Streams of Knit dyeing and finishing. SL.NO

Processing Unit

Possible pollutants in the waste water

Waste water volume

01

Scouring

NaOH,,Waxes, grease Na2Co3, Na2O2, SiO2 And fragments of cloth.

Small 10 L/ kg of cloth

02

Bleaching

NaOCl, Cl2, NaOH, H2O2, Acids etc.

Mostly washing

03

Dyeing

Large

04

Finishing

Various dyes, salts, alkalies, Acids, Na2S,Na2S2O2 and soap etc. Different finishing agent,

Very small

Nature of waste Water Strongly alkaline, dark color, high BOD (30% of total) Alkaline constitutes, approx 5 % of BOD Strongly colored, fairly BOD (6 % of the total) Low BOD

The above table shows the detail discharges at various stages of processing, however the overall discharges of a Knit Dye house are as follows; Color (organic substance), Na2 SO 4 (inorganic), NaOH, NaHOCl (Sodium hypochlorite), Na2 SO 3, Surfactant (LAS, BIAS, CIAS), (NH)3 SO4, H2O2,CH3COOH (Organic), paraffin (organic), Cellulose, Oil (Organic), Soap (Organic); all these things are COD and BOD. The fate of the above mentioned pollutant chemicals vary, ranging from 100% retention on the fabric to 100% discharge with the effluent. Generally, a wet processing industry generates wastewater possessing various level of toxicity. Textile finishing industry uses large amounts of 7


water, mainly because of washing operations. If these wastewaters are discharged into the environment they will cause serious and harmful impact not only on under ground and surface water bodies and land in the surrounding area but also will have an adverse effect on the aquatic ecological system. Effluents from textile mills also contain various types of metals, which has a cumulative effect, and higher possibilities for entering into the food chain and may cause various types serious diseases. Due to usage of dyes and chemicals, effluents are dark in colour, which increases the turbidity of water body. This in turn hampers the photosynthesis process, causing the death of many aquatic plants. If aquatic dyes then more oxygen will be required to consume them by bacteria thus causing a reduction of dissolve oxygen in the water. Various types of dyes are used in dyeing of various types of textiles fibres. Fixation capability of different dyes is different. The higher the fixation capacity the lower is the pollution problem. Table 1.2 shows the quantity of unfixed dyes and pollutants of various colouration processes while table 1.3 shows the degree of fixation of various dyes.

Table 1.2: Type of pollution associated with various coloration processes. Fibre Cotton

Dyes Class Direct Dyes

Cotton

Reactive Dyes

Cotton

Vats Dyes

Cotton

Polyester

Sulphurs Dyes

Disperse Dyes

1. 2. 3. 1. 2. 3. 1. 2. 3. 1. 2. 3. 4. 1. 2. 3.

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Type of pollution Salts Unfixed dye (5 – 30 %) Copper salts, Cationic-fixing agents. Salts Alkali Unfixed dye (10 –40 %) Alkali Oxidizing agents Reducing agents Alkali Oxidizing agent Reducing agent Unfixed dye (20 –40 %) Reducing agent Organic acid Unfixed dye (5 – 20 %


Table 1.3: Degree of fixation of various dyes. Class of dye Sulphur Vat Azoic Reactive Disperse Pigment 1:2 Metal Complex Dyes on wood Basic Acid

Degree of fixation (%) 60-70 80-95 90-95 50-80 80-92 99 95-99 97-98 80-93

The pollution level of textile wastewater is expressed in terms of BOD, COD, TSS, TDS, heavy metals and also temperature of the discharging effluent. At higher temperature the rate of transfer of gaseous oxygen into dissolved oxygen is reduced on the other hand at high temperature the activities of various aquatic species increases so that they require greater amount of oxygen. Thus at high temperature the demand of oxygen increases while its supply decreases. Various types of dyes and chemicals are used in textile wet processing industry. The pollution capabilities of different chemicals are different. Some are highly polluted while some are less polluted. Table 1.4 shows the pollution capability of various types of dyes and chemicals in textile wet processing. Table 1.4: Pollution capability of some of the chemicals/ products used in the Textile Industry. General Chemical Type

Difficulty of Treatment

Alkalies, Mineral acids Oxidizing agents Starch sizes, Vegetable oils, fats and waxes Biodegradable surfactants, Organic acids Reducing agents Dyes and fluorescent brighteners Fibres and polymeric impurities Polyacrylate sizes, Synthetic polymer finishes, Silicones Wool grease, PVA sizes, Starch ether and esters, Mineral oil, Surfactants resistant to biodegradation, Anionic and nonionic softeners. Formaldehyde and methylol reactants Chlorinated solvents and carriers 9

Pollution Category

Relatively harmless. Inorganic pollutants.

1

Readily biodegradable.

2

Dyes and polymers, Difficult to biodegrade. 3 Difficult to biodegrade, Moderate BOD. Unsuitable conventional

4 for


Cationic retarders and softeners Biocides Sequestering agents, Heavy metal salts

biological treatment, negligible BOD.

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The level of the polluting parameters is very high in textile mill wastewater as compared to the their acceptable values recommended by the Department of Environment, Government of Peoples Republic of Bangladesh (GOB). Off course the acceptable level of the pollutants varies somewhat form country-to-country and even within the country. The main reason for this is the wastewaterreceiving environment. If the effluent is discharged into a very big river or sea in that case vary little or no treatment is necessary as the wastewater will have very little or no effect on such a large water body. However if the same effluent is discharged into a small river or canal in that case off course it will be necessary to treat the wastewater since the effluent will have significant effect on the receiving water. Table 1.5 shows the values of the important pollutants found in the wastewater of the ……………… Apparels Limited Table 1.6 shows the acceptable values of the above pollutants of wastewater suggested by the Department of Environment, GOB. It will be seen in table 1.5, that reference has been made about a range rather than a particular value of the parameters. This is because the characteristics of textile wastewater are not always same which is due to the variation of raw materials, dyes and chemicals etc. For example a factory sometime process 100% cotton and sometime process 50/50 cotton & polyester blend or even 100 % polyester. The three different cases will require different dyes and chemicals. For white goods no dyes are used at all, in that case the effluent characteristics will be different from that of dyed effluent. For sized fabrics the effluent characteristics will be different from that of knit fabrics. The values shown in table 1.5 are presented from our long time experience about the effluent characteristics of similar plants. The ETP is designed in a such a way so that if the your factory changes the processing nature to some other products, even then the etp will be able to handle the treatment efficiency without any problem.

Hydraulic diagram of the plant 10


3. Basis of the Plant Design 11


3.1 Source The raw effluent shall be discharge to the proposed effluent treatment plant from the dyeing and finishing section of the ……………..Apparels Limited. 3.2 Quantity The quantity of effluent to be treated shall be of the order of = 960 m3 / day. 3.3 Capacity of the Effluent Treatment Plant (ETP). The effluent treatment plant has been designed on the basis of the following • • • • •

Dyeing capacity is 10,000 kg /day Contaminated effluent is 50% Less Contaminated effluent is 50% Operated continuously for 18 hours a day. Flow rate of treatment envisaged is 30 m3 / hr.

3.4 Inlet Effluent Characteristics Sl.No Parameters

Unit

Values

1 2 3 4 5 6 7 8

mg/L mg/L mg/L mg/L mg/L Co-pt unit 0 C

8 –14 400 - 600 800 - 1,200 200 - 500 3,000 - 6,000 30 – 60 Dark Mixed 600 C

PH BOD COD TSS TDS OIL & GREASE COLOUR TEMPERATURE

3.5 Outlet Effluent Characteristics-Bangladesh Standard Sl. No. 1 2 3 4 5 6 7 8

Water quality parameters PH BOD COD TSS TDS Oil & Grease Color Temperature

Unit ---mg/L mg/L mg/L mg/L mg/L Co-pt unit 0 C

Standard value for discharging into * Inland river On land for irrigation 6-9 6-9 <50.0 < 100 <200.0 < 400 <150.0 <200 <2100 < 2,100 < 10 < 10 <150 <150 <300C < 30 0C

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4. Treatment Philosophy As was mentioned the method of treatment of wastewater varies a lot. It mainly depends on the characteristics of effluent, volume of effluent, level of toxicity to be removed and the type of environment to receive the effluent. It was also suggested by some standards that the effluent might require very little or no treatment at all if the effluent is discharged into a very large river or sea. The treatment process that has been adopted for the Effluent Treatment Plant installed at …… ………………….. Limited is known as physico chemical and followed by biological. The physico chemical process consists of screening, coagulation and flocculation and sedimentation. The physico chemical process removes a substantial part of all the parameters shown in table 3.4 The biological treatment is responsible for removal of the rest of the removable BOD and some COD as well. The biological treatment is carried out by moving bed biofilm reactor (MBBR) in the biological tank. MBBR is a new concept of wastewater treatment and was developed by a Norwegian company known as AnoxKaldnes’. MBBR is a highly efficient method of reducing the BOD of a body of wastewater.

Figure 1: Moving bed plastic media

Figure 3: Bacteria in the plastic media

Figure 2: Bacteria in the plastic media

Figure 4: Bacteria in the plastic grid media

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The MBBR™ biofilm technology is based on specially designed plastic biofilm carriers or biocarriers that are suspended and in continuous movement within the biological tank or reactor of specified volume. The design of associated aerators, grids, sieves, spray nozzles and other integral parts to the reactor is also of great importance in making up the system as a whole. The system is suitable for treating both industrial as well as municipal wastewater. The textile effluent is led to the MBBR treatment reactor where biofilm, growing within the internal structures of the biocarriers, degrade the pollutants. These pollutants that need to be removed in order to treat the wastewater are food or substrate for growth of the biofilm. The biocarrier design is critical due to requirements for good mass transfer of substrate and oxygen to the microorganisms and there is a continuous R&D in the area of the MBBR biofilm technology. Excess biofilm sloughs off the biocarrier in a natural way. An aeration grid located at the bottom of the reactor supplies oxygen to the biofilm along with the mixing energy required to keep the biocarriers suspended and completely mix within the reactor. Treated water flows from reactor through a grid or a sieve, which retains the MBBR™ biocarriers in the reactor. The various stages of the plant treatment procedure is elaborated as follows; After biological treatment the effluent is passed through sand filter and finally though the activated carbon filter. The activated carbon filter is highly successful in removing BOD, COD, TSS, TDS & color of the effluent. 4.1. PRE-TREATMENT 4.1.1 Screening - to remove coarse materials 4.1.2 Equalization & Skimming - to remove grease & oil and homogenize and to remove some BOD & COD. 4.2. PRIMARY TREATMENT 4.2.1 Coagulation - to coagulate the suspended solid to coagulate 4.2.2 Flocculation - to flocculate by coagulants 4.2.3 Neutralization - to adjust the pH between 6.5 to 8.5 4.2.4 Sedimentation – to precipitate small suspended solids All the above processes contribute to removal of substantial amount of all the polluting parameters.

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4. 3. SECONDARY TREATMENT Biological treatment (MBBR)- to remove BOD and COD & to decompose organic matter. 4. 4. TERTIARY AND OTHER TREATMENTS 4.4.1

Granular Media Filtration-to removes TSS and any other pollutants in the form of particle. This filter is also useful to protect the Activated Carbon Filter (ACF) from overloading by pollutants such as particulates, organics.

4.4.2

Activated Carbon Filter- Carbon adsorption is a proven process in tertiary treatment for the processing biologically treated wastewaters, and is one of the many processes used in the advanced treatment of wastewaters. The ACF is used to remove relatively small quantities of refractory organics, as well as inorganic such as sulfides and heavy metals remaining in an otherwise well-treated wastewater.

4. 5. SLUDGE MANAGEMENT & DISPOSAL 4.5.1

Sludge disposal – to separate the sludge from the thick slurry and then dispose of the sludge as dried cake

5. PROCESS FLOW CHART 15


6. Operational Processes 16


6.1.Pre-Treatment The effluent generated in a textile wet processing plant can be broadly classified into two classes e.g i) Less contaminated and ii) Highly contaminated. The Less contaminated waters are mainly generated due to machine washing, floor cleaning, waters coming from the last washing cycles etc. These less contaminated waters pose very little threat to the environment; therefore they can be discharged directly to the environment or may require little treatment. If however these waters are mixed with the main effluent, then the volume of total effluent will be very high and as a result overall install capacity running cost of the ETP will be very high. Therefore the less contaminated waters are stored in a separate tank and from time to time the effluent is pumped to the sand filter followed by carbon filter and finally to the discharge outlet. The more contaminated waters are guided through the bar screen to the equalization tank for various treatments. 6.1.1 Screening (To remove coarse and float materials.) The raw waste water (Raw Effluent) from the process of the plant would first be screened through a manual bar screen strainer channel, where all particles with dia.> 5 MM as well as small pieces of the fiber and floating suspended matters like polythene paper, polythene bags, rags and others materials are removed by bar screen net. The bar screen consists of parallel rods or bars and is also called a bar rack. These devices are used to protect downstream equipment such as pumps, lines, valves etc. from damage and clogging by rags and other large objects. The bar screen is cleaned manually by means of rakes. The screening is disposed off suitably after they are de-watered. The screened clean effluent flows by gravity to an equalization tank. 6.1.2 Equalization and Skimming (To remove grease & oil and homogenize) The raw wastewater from the screen channel is collected in the equalization tank, where it is equalized with respect to its characteristics, homogeneity, flow and an uniform pollution load as well as to make bacteria acclimatized. High-speed aerating devices are fixed at the bottom of the equalization tank, which blows air through the waste at a rate about 0.1 CUF of air per gallon of effluent. The rising air tends to coagulate the grease and oils and cause them to rise to the surface where they can be removed by a scraper mechanism. Besides, the airflow accomplishes a proper equalization of both varying loading and fluctuating PH values. The equalization tank is designed for hydraulic retention time of around 6 hours. Certain amount of COD will also be removed by the dissolved air flotation process. The following benefits are derived from the flow equalization process; 1. Biological treatment is enhanced, as the shock loadings are eliminated or minimized, inhibiting substances diluted, and pH stabilized. 2. Chemical treatment is improved if chemical dosing is controlled to provide consistent performance 3. The effluent quality and thickening performance of secondary sedimentation units are improved through constant solids loading. 17


4. Effluent surface area requirements are reduced, filter performance is better, and more uniform filter-backwash cycles are possible. 6.2. Primary-Treatment 6.2.1 Coagulation and Flocculation (To remove color and effluent suspended) The homogenized effluent will then be pumped to a flash-mixing tank followed by a flocculation tank. In the flash-mixing tank coagulants like lime (Calcium Hydroxide) and flocculants like ferrous sulfate (FeSO4) are dosed. This is done for coagulation and removal of the total dye particles. The basic idea of adding coagulant is to bring together all the suspended and dye particles so that they can be precipitated out in the flash mixing tank and flocculation tank by coagulation and flocculation mechanism. The chemical reaction that occurs in the coagulation and flocculation process is shown below; CaO + H2O

Ca (OH) 2

The above reaction take place in lime dosing tank when lime reacts with water and we get calcium hydroxide solution. This solution reacts with the ferrous sulphate solution, which as follows Ca (OH) 2 + FeSO4

CaSO4 + Fe (OH) 3 + FeSO4 (Unreacted) + Fe (OH) 2

Adequate quantity of polyelectrolyte polymer solution is dosed in the flocculation tank to enhance the process of colour removal by the flocculation process. A substantial amount BOD and COD etc. are removed in the coagulation and flocculation process. 6.2.2 Precipitation and Sedimentation in Tube Settler -1. (To remove the flocs materials) From the flocculation tank the effluent is taken by natural gravity in to the tube settler- 1 tank where the dyes and suspended particles are precipitated. The flocs formed are removed in the downstream tube settler –1 by the help of tube settler media. The effluent will further flow by overflow system to the pH correction tank where requisite quantity of acid will be dosed and pH will be adjusted as per the requirement. 6.2.3 pH Correction (To adjust the inlet pH) The effluent from tube settler- 1 tank is then taken by overflow method to the pH correction channel for neutralization, where 33% HCl acid is dosed for neutralizing the pH value around 7 to 8. The pH correction channel is designed for hydraulic retention time of around 1 -2 minutes and is provided with slow speed agitator for thoroughly mixing of waste with acid to maintained pH value. 6.3 Secondary-Treatment 18


6.3.1 Biological Treatment in the Fluidized Aerobic Bio-Reactor (also called MBBR) # 1 & 2 (To reduce the remaining BOD / COD aerobically). The neutralized effluent is then taken by gravity in to the biological treatment aeration tank for biological degradation of available organic matter to reduce the remaining BOD and COD aerobically. The biological treatment tanks are designed on extended aeration principle. The fluidized Aerobic Bio-Reactor I & II includes two tanks of any shape filled up with small carrier elements. The two tanks are also called Moving Bed Biofilm Reactor (MBBR). The media elements are made up of special grade plastic of controlled density such that they can be fluidized using an aeration device. In course of treatment a bio-film develops on the elements, which move along with the effluent in the reactors. The movement within the reactors is generated by providing aeration with the help of diffusers placed at the bottom of the reactor. The thin bio-film on the elements enables the bacteria to act upon the biodegradable matter in the effluent and reduce the BOD content while the rapid and turbulent movement of the effluent in the presence of oxygen available from the air, certain amount of COD is also removed. The chemical reactions that took place in the FAB reactor can be defined according to the following three processes; A. Oxidation process COHNS

+ O2 + Bacteria + DAP & UREA

CO2 + NH3 + Energy + Other end Products

DAP and Urea is used as food for the microorganism. B. Synthesis Process COHNS + O2 + Bacteria

C5H7NO2 (New bacteria)

C. Endogenous Respiration C5H7NO2 + 5O2

CO2 + NH3 + 2H2O

Apart from the above basics reaction there are some other reactions that take place in the FAB reaction tanks. During aeration the oxygen reacts with C, S and N which is shown below. C + O2 CO2 S + O2 SO2 N + O2 NO2 Some untreated ferrous sulfate and ferric hydroxide reacts with oxygen and the reactions are as follows, 19


FeSO4 + O2

Fe2 (SO4) 3

Fe (OH) 2 + O2

Fe (OH) 3

When the plant is kept shut down for short period of time, at that time, off course, it will be necessary to continue the aeration of Biological reactor 1 & 2. The biological degradation process in enhanced by the adding some Dia-mmonium Phosphate (DAP) and UREA, which acts as food for the microorganism. Therefore it will be necessary to supply food for the bacteria. Thus a combined solution of Urea and DAP are dosed in the biological tank to feed the bacteria. 6.3.2 Tube Settler –2 (To remove the biological solids generation. ) From the biological reactor the treated effluent flows by gravity to the tube settler –2. The biological solids generated are removed from the tube settler –2 by the help of tube settler media. 6.3.3 Filter Feed Sump (To collect effluent for next processes) The treated effluent from tube settler- 2 overflow in to the filter feed sump. From the filter feed sump the effluent is pumped to the pressure sand filter at first and then through activated carbon filter. From here the disinfected effluent is pumped by means of the pressure sand filter feed pump to the pressure sand filter. The pump is normally operated in automatically with interlock to the level switch in the filter sump. 6.3.4 Pressure Sand Filter (To remove suspended matter) From the filter feed sump the effluent is pumped to the pressure sand filter. The filtration takes place in the downward mode. The filter is filled with a layer of graded sand media supported by a layer of graded gravel. The suspended matters in the effluent are filtered out in this unit; the effluent is then flown into the activated carbon filter. It was mentioned in the section 6.1 that the less contaminated waters are collected in the separate tank and then pumped to the sand filter tank followed by carbon filter and discharge outlet. It is necessary to backwash the sand filter every eight hours. 6.3.5 Activated Carbon Filter (To absorbed the dissolved organic matter) The treated and filtered effluent from the pressure sand filter flows into the activated carbon filter. In this unit too the feed flow is downward through a layer of granular activated carbon filter in which dissolved organics of the effluent are absorbed. It is necessary to backwash the carbon filter every eight hours. 6.3.6 Treated Effluent Disposed Off (Ready for disposed off) The treated effluent emerging from the ACF is directly disposed off through the out let channel to environment. 20


6.3.7 Sludge Treatment and handling The sludge generated in the flash mixing tank, flocculation tank, tube settler-1, tube settler-2 and biological reactor is taken to a sludge sump. Here also aeration is carried out. The waste is then pumped to a Sludge Thickener tank where the sludge is concentrated at the bottom of the tank. The thickened sludge from the thickener is pumped to centrifuge pump for de-watering. At first the centrifuge is started and then the thickener feed pump is started. As the slurry of sludge flows polyelectrolyte solution is dosed in the centrifuge as a result the sludge will be separated from the water. The centrifuge is run for 20 to 30 minutes and then switched off. The de-watered sludge is transformed into cake form. The dried cake may be disposed of to deliver in the brickfield for burning. The overflow from the sludge thickener will be flow back to equalization tank for further treatment. In some cases due to the nature of the wastewater characteristics it is not possible to dewater the sludge into a cake form, in that case the sludge is collected in the form of slurry in a bucket just below the centrifuge pump. After collection of the sludge, it is strongly advised to dispose the sludge in such a way so that it will not come in contact with the environment. A best way to handle this sludge is to throw them in a deep hole, when the hole is nearly filled then it will be necessary to bury the sludge by means of soil. In every two days the sludge cake is taken out by opening the cover of the centrifuge. After taking out of the cake the centrifuge is washed and clean by water. The water that has been separated from the sludge will be flown back to equalization tank for treatment.

7. Operational Procedure 7.1 Preparation of the chemical dosing

21


Before starting the operation it will be necessary prepare all the necessary chemical solutions. The procedures of preparing the solutions are described below. 7.1.1 Preparation of the Lime solution The daily requirement of the lime solution is calculated and shown in section 8.1. During preparing the dosing solution of lime a 5% solution is prepared. In this regard the dosing tank, which is fitted with a motor and stirrer, is at first filled with 1000 litres of water. After that 50 kgs of lime is added and the motor is switched on to stir the solution. The stirring should be continued on a 24-hour basis i.e. as long as the plant runs. After that the solution is ready for dosing in the flash-mixing tank. It is necessary to adjust the stroke of the dosing pump to get the desired flow. 7.1.2 Preparation of the Ferrous Sulphate (FeSO4) solution The daily requirement of the ferrous sulphate is calculated and shown in section 8.2. During preparing the dosing solution of ferrous sulphate a 10% solution is prepared. In this regard the dosing tank, which is fitted with a motor and stirrer, is at first filled with 1000 litres of water. After that 100 kgs of ferrous sulphate is added and the motor is switched on to stir the solution. The stirring is continued for nearly 1 hour. After that the solution is ready for dosing in the flashmixing tank. It is necessary to adjust the stroke of the dosing pump to get the desired flow. 7.1.3 Preparation of the Poly Electrolyte (PE) solution The daily requirement of the PE solution is calculated and shown in section 8.3. During preparing the dosing solution of lime, a 0.05% solution is prepared. In this regard the dosing tank, which is fitted with a motor and stirrer, is at first filled with 1000 litres of water. After that 500 gms of PE is added and the motor is switched on to stir the solution. The stirring should be continued on a 24hour basis i.e. as long as the plant runs. After that the solution is ready for dosing in the flash mixing tank as well as centrifuge tank. It is necessary to adjust the stroke of the dosing pump to get the desired flow. 7.1.4 Preparation of the Acid solution The daily requirement of the Acid solution is calculated and shown in section 8.4. During preparing the dosing solution of acid, a 2.5% solution is prepared. In this regard the dosing tank, which is fitted with a motor and stirrer, is at first filled with 1000 litres of water. After that 70 litres of 33% HCl is added. After that the solution is ready for dosing in the flash-mixing tank. It is necessary to adjust the stroke of the dosing pump to get the desired flow. 7.1.5 Preparation of the Diammonium Phosphate (DAP) and Urea solution The requirement of the DAP and Urea is calculated and shown in section 8.5. During preparing the dosing solution of DAP and Urea a 5% mixed solution is prepared in the same dosing tank. In this regard the dosing tank, which is fitted with a motor and a stirrer, is at first filled with 1000 litres of water. After that 50 kgs of DAP and Urea (35 kgs Urea and 15 kgs DAP) are added and the motor 22


is switched on to stir the solution. The stirring should be continued for half of an hour. After that the solution is ready for dosing in the biological tank. It is necessary to adjust the stroke of the dosing pump to get the desired flow. 7.2 Method of seeding bacteria in the FAB reactor # 1 & 2. The following steps are to be followed during start up of FAB reactor. 1. Check whether civil work is complete in all respects as far the civil GA drawings. 2. Check any leakage 3. After completing the civil work, assemble air pipes. Fill the water tank. Take trial for air diffusion. Aeration has to be uniform and there should not be any leakages in the air grid. 4. If aeration is o.k. drain water and pour FAB media in the reactor. 5. Fill the tank up to the water level 6. Add 10 tons of filtered cow dung. Ensure that cow dung is free of foreign material and fibres. Make 5-10% slurry. Filter it through 2-3 mm opening mesh. During the addition of slurry in FAB keep the blowers on. Cow dung should be fresh (3 to 4 days) . We can also have aerobic culture in FAB in place of cow dung. Add this slurry uniformly in all the compartments. 7. Aerate the dilute slurry continuously for about 5-6 days. 8. Dilute effluent can be loaded after this gradually; (Starting with 10% of design BOD load, for initially 7-8 days thereafter the load can be increased after every 4-5 days by 10% provided BOD reduction is continuously 70-75% is observed at the increased BOD load. If, in cases, the bacteria of the biological reactor dye for any reason like wrong acidity or alkalinity, nor aeration shock load etc, in that case it will be necessary to seed the bacteria again. This has to be done by means of adding 10 tons of cow dung as was mentioned in section 6 above. It is not very easy to detect the presence of bacteria in the biological tank. By means of using a microscope it will only be possible to test the presence of bacteria in the effluent. Apart from this by testing the BOD of the effluent before and after the biological reactor treatment it will be possible to say whether there is any bacteria in the reactor or not. If the quantity of BOD is same before and after the biological reaction then we can say that there are no bacteria to reduce the BOD. On the other hand, if the BOD is reduced, after, treatment in the biological reactor then we can say that there is bacteria in the biological tanks.

7.3 Important processing tips 7.3.1 1. Drain the sludge settled at the bottom of the tube settler at periodic interval to avoid carry over of sludge. 2. Changeover from operating to stand by equipment every day. 23


3. Regularly follow the lubrication and maintenance schedule for all mechanical moving items. 4. Take samples from the locations specified. Analyze them and maintain logbook regularly to ensure better control over operation of the plant. 7.3.2 1. Do not let effluent –having pollutants more than specified range in the plant . 2. Do not enter in to the closed tank without opening the manhole/without draining the contents of the tank. 3. Do not handle chemicals, dosing system without taking precautions. 4. Do not allow acidic pH < 6 or alkaline pH > 8.5 or hot (temp > 400C) 5. Do not drain the FAB reactor under normal operation. 7.4 Trouble Shooting guide 7.4.1 Aeration Problem Low DO and/or septic odor in FAB reactor Possible cause Under aeration

Blower operation not continuous Grid are damaged

High inlet Organic i.e BOD/COD load

Necessary Check and possible corrective actions 1. Check DO, should be in the range of 1.0 to 3.0 mg/L throughout in the tank. 2. Check the air quality delivered by blower, in case the quantity is less than design; check the blower for any mechanical problem. In case of any mechanical problem refer the blower manual for the maintenance. 3. Check for adequate mixing in FAB reactor. The blower should be in continuous operation In case the grid is damaged, this will result in excessive turbulence but low oxygen transfer. The corrective action should be taken nfor reparing the diffuser/grid. 1.In case the BOD/COD load is higher than design, the same to be controlled prior to E.T.P. If the increase is for a small period the flow to the plant to be reduced to decrease the kg BOD/COD loading. 2.Solid level in the FAB reactor very high, the settled solids (if any) to be drained. The draining frequency can be ascertained based on the site condition.

24


7.4.2 Foaming Problem Possible cause Over aeration

Necessary check and possible corrective actions Check BOD loading (kg/d), in case the BOD level is much lower than the design basis. Adjust the air quantity to the bio reactor and maintain minimum D.O level as 2.0 mg/l

Low bacterial level in the FAB reactor

Seeding should be done preferably by using activated sludge from an well-operated plant

Note- The foaming problem usually occurs during start-up and is only temporary. If you are under starting up do not be alarmed by it. 7.4.3 Low oxygen uptake in FAB reactor Possible cause High Temperature

pH out of range Spill Low organic loading

Necessary check & possible corrective actions At high temperature there will be decreased oxygen utilization. Maintain the inlet effluent temperature between 250C to 350C maintain organic removal Eliminate source of pH upset Adjust pH in FAB reactor to between 6.5 and 8.5 Eliminate source of spill Evaluate effect of spill on active Bio Mass. Adjust the air supply according to the inlet BOD load, simultaneously maintain the DO level >2.0 mg/l.

7.4.4 Low Bio Growth in the FAB reactor Possible Cause High Temperature

pH out of range

Necessary Check & Possible Corrective Actions High process temperature can result in decreased oxygen utilization and as a result low bacterial growth. Apart from this at high temperature there is possibility of dyeing of the microorganisms. Maintain the inlet effluent temperature between 250C to 350C to maintain organic removal Eliminate source of pH upset as it will adversely affect the Biological process. 25


Insufficient aeration

Shock loading

Adjust pH in FAB reactor in between 6.5 and 8.5 Insufficient aeration may lead to decrease in bacterial population. The aeration should be continuously carried. Even if the effluent is not available for a short span in a day blowers should not be stpped. The effluent having pollutant level very high should be segregated and stored separately. The effluent having toxic pollutant should be prevented from entering the ETP.

7.4.5 High suspended solids level in the tube settler II outlet effluent Possible cause Media position

Excessive storage of sludge in the tube settler.

Trough are not cleaned

Necessary Check & Possible Corrective Actions Check the position of tube settler media by lowering the water level, in case any short circuiting is there, the same is required to be corrected by correctly positioning the media as per the drawing. The sludge needs to be drained periodically from the tube settler. In case the sludge level increases in the tube settler the same will result in sludge carry over. The trough should be cleaned manually periodically.

7.4.6 High COD (or BOD) level in tube settler II outlet effluent Possible cause Low Bio mass High organic loading and/or excessive flow

High effluent suspended solid (SS)

Necessary Check & Possible Corrective Actions Seeding of FAB reactor may be required. Increase in the inlet BOD/COD load in comparison to Design. If the increase is for a short time decrease the flow to maintain the kg BOD loading as far design. If COD increase is attributable to high effluent suspended solids, refer to corrective actions for “high effluent suspended solids” 26


Inadequate DO

Check organic loading by measuring COD. Increased oxygen utilization can result from increased organic loading. Refer to corrective actions for “low oxygen level in FAB Reactor”

8.Estimation of various chemicals The requirements of various chemicals must be determined by means of jar test. It is strongly recommended to conduct the jar test whenever any major changes occurs either in selection of 27


process, dyes, or raw material characteristics. Different process condition due to change of raw material or change of brand of dyes will lead to different types of effluent characteristics. 8.1 Estimation of quantity of lime (Calcium Hydroxide) :From our experience of running plants and jar tests, the quantity of required lime can be estimated as follows; If the flow of effluent is 30 M3/Hr. Dose optimized by jar test = 833 mg / l. Therefore, CaO required =

30 M3 /hr. X 833 mg /l X 24 hrs. --------------------------------------------- = 600 Kg / day. 1000 = 25 kg/hr

8.2 Estimation of quantity of Ferrous Sulphate FeSO4. Based on experience or by jar tests findings the dosages can be stabilized. e.g. If flow of effluent is 40 Cum / Hr. Dose optimized by jar test = 833 mg / l. Therefore 30 M3 /hr. X 833 mg /l X 24 hrs. FeSO4 required = ------------------------------------------------1000

= 600 Kg / day. = 25 kg /hr

8.3 Estimation of quantity of Polyelectrolyte. Based on experience or by jar tests findings the dosages can be stabilized. e.g. If flow of effluent is 30 Cum / Hr. Dose optimized by jar test = 4.16 mg / l. Therefore, Polyelectrolyte required

30 M3/hr X 4.16mg / l X24 hrs = -------------------------------------------- = 3 kg / day 1000 = 0.125 kg / hr

(This amount will be required for dosing in the flash mixing as well as centrifuge feed pump)

28


8.4 Estimation of quantity of Hydrochloric Acid ( HCl) These can be optimized by using Jar test procedure given bellow Based on experience or by jar tests findings the dosages can be stabilized. e.g. If flow of effluent is 30 M3/Hr. Dose optimized by jar test = 375 mg / l Therefore HCl –33% required =

30 M3 / hr X 375 mg/l X24 hrs ---------------------------------------------- = 270 Kgs / day 1000 = 11.25 kgs / hr

8.5 Estimation of quantity of DAP and Urea Assume BOD content of the feed to the system = 200 mg/ l. Flow of effluent to the system is 30 M3/ hr. 30 X 200 X 24 Total BOD load = ------------------------ = 144 Kgs /day. 1000 Basis for activated sludge process is BOD : N : P = 100 : 5 : 1. 144 X 5 For 192 kgs / day BOD Nitrogen required. = -------------- = 9.6 kg /day. 100 144 X 1 Phosphorus required = --------------- = 1.44 Kg / day. 100 Now, DAP contains 17.9 % phosphorus, for 1.92 Kg phosphorus, DAP required. 1.44 X 100 = -----------------17.9

= 8.04 Kgs / day =0.34 kg / hr

DAP contain 18 % Nitrogen, therefore Nitrogen provided by 8.04 kg DAP is 8.04 X 18 = ------------------- = 1.45 kg. 100

29


Nitrogen shortfall = 8.04– 1.45 = 6.60 Kg / day. Now, urea contains 46 % Nitrogen, so for 7.68 Kg Nitrogen, Urea required is 6.60 X 100 = ----------------------- = 14.35 Kg / day. 46 = 0.60 kg / hr. Therefore, Urea required is 14.35 kg/day DAP required is 8.04/day Note: The Urea and DAP solutions are required to feed the bacteria i.e. they works as nutrient for the microorganisms. If, for any reason, the plant is kept shut down due to closure of the factory or something like this, even then it will be necessary to run the biological reactor along with dosing DAP and Urea solutions. This is because if the biological reactors are shutdown the bacteria will dye and then again it will be necessary to seed the bacteria according to the procedure outlined in section 7.2. Chemical Consumption/day @ (100% Efficiency) Chemicals

Quantity/day

Quantity / hr

CalciumHydroxide(Lime Crystal) 85% Purity Ferrous sulphate (FeSO4) 85% Purity Polyelectrolyte(Anionic PE 100% Purity) Hydrochloric acid 33% purity Dia ammonium phosphate Urea

600 Kg /day

25.00 kgs/ hr

600 Kg/ day

25.00 kgs/ hr

3 Kg /day

0.125 hg/ hr

270 Kg /day 8.04 Kg /day 14.35 Kg /day

11.25 kgs / hr 0.34 kg / hr 0.60 kg / hr

Note: The actual quantities will depend on chemicals purity , effluent characteristics and jar test. The above indicate consumption pattern. These are not guarantee figures

30


9. Commissioning of the Plant a. At first sufficient effluent is allowed in the equalization tank. After that aeration should be continued. After aeration for about an hour or two the effluent is pumped to the flash mixing tank. b. Lime and Ferrous Sulphate solution should be dosed as soon as the effluent accumulated in the flash mixing tank. Soon after dosing, the colour of the effluent will be changed and the dissolved matters will form small flocks. The effluent will then be flown to the flocculation tank by overflow and gravity principle. c. Polyelectrolyte is then dosed when the small sludge particles will concentrated at the bottom of the tank. d. From the flocculation tank the effluent is over flown to the tube settler 1 where the effluent is flown upwards through the tube media. Under this condition a substantial amount of sludge will be accumulated at the bottom of this settler tank. e. The effluent is then goes to the pH correction channel due to the over flow. It is necessary to check the pH of the effluent at this stage and if the pH is above 7 then acid solution is dosed to bring down the pH within a range of 6.5 to 8.5. f. The effluent is then goes to the Fluidized Aerobic Biological reaction tank #1 due to the over flow and gravitation method. Microorganisms like bacteria are seeded in Fluidized Aerobic Biological reaction tank #1 & 2 tank, which is described in section 7.2. g. Nutrients are dosed in the FAB reactor for nursing microorganisms like bacteria. When this tank is filled with, the effluent is then flows to the Fluidized Aerobic Biological reaction tank # 2. At this stage the remaining BOD/COD will be reduced. From the Fluidized Aerobic Biological reaction tank # 2, the effluent enters into the tube settler # 2. This is also happen due to overflow. h. As the effluent flows through the tube media the sludge is settled at the bottom of the tank. i. From the tube settler tank # 2 the effluent goes to the filter feed sump due to gravity. From the filter feed sump the effluent is pumped to the pressure sand filter or Granular Media Filtration-to remove carbonaceous BOD and nitrogenous and residual in solubilised phosphorous. This filter is also useful to protect the down stream Activated Carbon Filter (ACF) from overloading by pollutants such as particulates, organics.

j.

The effluent is then flows to the Activated Carbon Filter. Carbon adsorption is a proven process in tertiary treatment for the processing biologically treated wastewaters, and is one of the many processes used in the advanced treatment of wastewaters. The ACF is used to remove relatively small quantities of refractory organics, as well as inorganic such as sulfides and heavy metals remaining in an otherwise well-treated wastewater. k. The water at this stage is safe to be released into the environment.

31


10. Plant Shutdown In cases when the factory is kept shut down for a short period of time then there will not be any effluent, in that case it will be necessary to continue aeration and nutrient dosing in the Fluidized Aerobic Biological reaction tank # 1 & 2, otherwise the bacteria will dye. If the bacteria dye then it will be necessary to seed bacteria again following section 7.2.

11. Maintenance of the plant 11.1 Bar Screen: The bar screen should be cleaned everyday 11.2 Equalization pump: The lube oil should be checked before starting the pump. The valve of the suction line should be opened and cleaned once every seven days. 11.3 Flash Mixing and flocculation agitator: Apply lube oil before starting the agitator motor. The lube oil should be checked after every seven days. 11.4 Air Blower: Check the lube oil before starting the air blower. If there is no lube oil then apply lube oil and start the blower. The lube oil pump should checked frequently. 11.5 Sludge transfer pump and centrifuge feed pump: After starting the sludge transfer pump and centrifuge feed pump it should be observed for a short period of time. If no sludge is found then stop the pump and open and clean the delivery line. 11.6 Agitators of all the dosing tanks: Check the lube oil every seven-day. Apply lube oil if finishes. 11.7 Flash mixing, flocculation and tube settler tank # 1: The tanks should be cleaned very well in every three months. The tube settler media should also be cleaned. 11.8 Tube settler tank # 2: This tank should be cleaned after every six months time. 32


11.9 Sand Filter: It is necessary to backwash the sand filter every eight hours. [

11.10 Carbon filter: It is necessary to backwash the carbon filter every eight hours. 11.11 Centrifuge: After removal of the cake, the inside of the centrifuge should be cleaned. Check the belt of the motor frequently, if loose change it so that it can rotate freely and easily. 11.12 Painting the plant: All the pipes and M.S tanks should be painted every year. The painting instruction and other details are given in Appendix-III 11.13 Information about various equipments, parts and accessories: SR. NO 01

DESCRIPTION Bar Screen

02

Aeration Grids for equalization tank.

33

SPECIFICATION Type – Coarse Model- Aquatech-03 Quantity – 1 ( One ) Size – 450 MM X 500 MM. Materials of construction – Mild Steel Epoxy Paint. Origin- Bangladesh. Type – Air diffuser Model- Aquatech -03 Quantity- 1 Lot Size- 80 MM, 40 MM. Material of construction- “U” PVC Temperature – 80 0C Origin – Bangladesh.


03.

Effluent transfer pump for equalization Type – Horizontal, Centrifugal, non Clog tank. Model- JOHNSON Capacity – 30 m3 / Hr. Head – 16 MWC Motor- 3.7 KW, Volt-400, 3 P, 50 Z. RPM- 2,900 RPM Quantity- 1 (One) Size- Suc. -80 MM Del.- 50 MM. Material of construction- CI Temperature – 80 0C Origin – India. With base frame, coupling, bolts etc.

04

Air blower for equalization tank.

Type – Twin lobe, rotary air Cooled, Horizontal Model-Everest Transmission. Capacity – 110 m3 / Hr. Discharge pressure – 4,500MMWC Motor- 3.7 KW, Volt-400, 3 P, 50Hz. RPM- 1,450 RPM Quantity- 1 (One) Size- Suc. - 100 MM Del.- 80 MM. Material of construction- CI Origin – India. With base frame, V belt, Pressure gauze, filter, silencer and non-return valve etc.

Air blower for biological reaction tank

Type – Twin lobe, rotary air Cooled, Horizontal Model- Everest Transmission. Capacity – 440 m3 / Hr. Discharge pressure – 6,500MMWC Motor- 15 KW, Volt-400, 3 P, 50Hz. RPM- 1,450 RPM Quantity- 1 (One) Size- Suc. – 100 MM Del.- 80 MM. Material of construction- CI Origin – India. With base frame, V belt, Pressure gauze, filter, silencer and non-return valve etc.

05

34


06.

Flash Mixture Mechanism.

Type – Pitch blade turbine impeller Vertical. Model- Aquatech- FM-03 Capacity – Heavy duty, suitable for Flash mixing tank. Motor- 1.5 KW, Volt-400, 3 P, 50Hz. RPM- 1,450 RPM Quantity- 1 (One) Material of construction- CI Origin – Bangladesh. Gear box- Aquatech Reduction ratio- 15: 1

07.

Flocculation Mixture Mechanism

Type – Pitch blade turbine impeller Vertical. Model- Aquatech- FM-03 Capacity – Heavy duty, suitable for Flash mixing tank. Motor- 1.5 KW, Volt-400, 3 P, 50Hz. RPM- 1,450 RPM Quantity- 1 (One) Material of construction- CI Origin – Bangladesh. Gear box- Aquatech Reduction ratio- 15: 1

08

Tube Settler Media for tube Settler # 1 Material of construction- PVC . Model – Aquatech- TSM-03 Type - Hexagonal Inclination angle – 60 0 deg.

35


SR. NO 09

DESCRIPTION

SPECIFICATION

Tube Settler Media for tube Settler # 2 Material of construction- PVC . Model – Aquatech- TSM-03 Type- Hexagonal Inclination angle – 60 0 deg.

10

Biological FAB Media for biological Reaction tank # 1 & 2.

Type – Corrugated Model- Aquatech-FAB-03 Quantity – 2 ( Two ) Materials of construction – Polypropylene Size- 20 MM x 16 MM height Origin- Bangladesh.

11

Aeration grids for biological reaction tank.

12

Sludge thickener mechanism.

13

Sludge Centrifuge for cake making.

Type – Air diffuser Model- Aquatech -03 Quantity- 1 Lot Size- 80 MM, 40 MM. Material of construction- “ U “ PVC Temperature – 80 0C Origin – Bangladesh. Type – Suitable of thickener tank Model- Aquatech- STM-03 Quantity- 1 ( One ) Material of construction – Mild Steel. Epoxy painted. Motor– 1.5 KW, Volt-400, 3 P, 50 Hz RPM- 1,000 RPM Gear box- reduction ratio. - 70:1 Origin- Bangladesh. Capacity – 100 Kg / batch Quantity- 1 (One) Model- Aquatech- HC-03 Type- Hydro extractor centrifuge Material of construction – Mild steel Basket size-Dia-850 MM X 550 MM Motor- 7.5 KW, V-400, 3 P, 50 Hz.

36


14

Filter feed sump pump

15

Less contaminated water pump

16

Thickener feed pump for sludge sump.

37

RPM- 1450 RPM Origin – Bangladesh. Type – Horizontal Centrifugal Pump Model- Submersible Capacity – 30 M3 / Hr. Discharge pressure- 15 MWC Head – 35 MWC Motor- 3.75 KW, Volt-400, 3 P, 50 Z. RPM- 2900 RPM Quantity- 1 ( One ) Size- Suc. -65 MM Del.- 50 MM. Material of constructionBody-CI Temperature – 80 0C Origin – India. With base frame, coupling, bolts etc. Type – Horizontal/Centrifugal Model- Submersible/centrifugal Capacity – 30M3 / Hr. Discharge pressure- 15 MWC Head – 35 MWC Motor- 3.75 KW, Volt-400, 3 P, 50 Z. RPM- 2900 RPM Quantity- 1 (One) Size- Suc. -65 MM Del.- 50 MM. Material of constructionBody-CI Temperature – 80 0C Origin – India. With base frame, coupling, bolts etc. Type – Horizontal Screw pump Model- Alpha Helical Capacity – 6 m3/hr. Discharge pressure- 15 MWC Head – 16 MWC Motor- 3.75 KW, Volt-400, 3 P, 50 Z. RPM- 2900 RPM Quantity- 2 (Two) Size- Suc. -65 MM Del.- 50 MM.


17

Centrifuge feed pump of hydro extractor For sludge cake making

19

Lime (Calcium hydroxide) Preparation tank agitator mechanism.

20

FeSO4 (Ferrous Sulphate ) preparation tank agitator mechanism.

38

Material of constructionBody-CI Temperature – 80 0C Origin – India. With base frame, coupling, bolts etc Type – Horizontal, Centrifugal, Screw, non-Clog. Model- Alpha Helical Capacity – 5M3/Hr. Discharge pressure- 15 MWC Head – 16 MWC Motor- 1.5 KW, Volt-400, 3 P, 50 Z. RPM- 1,450 RPM Quantity- 1 (One) Size- Suc. -80 MM Del.- 50 MM. Material of constructionBody-CI Temperature – 80 0C Origin – India. With base frame, coupling, bolts etc Location of dosing – Flash mixing Tank capacity – 1,000 liter. Quantity- 1( One) Material of construction- PVC Agitator mechanism- 1 ( One ) Motor- 0.75 KW, V-400, 3 P, 50 Hz RPM – 1000 RPM Origin- Bangladesh + India Location of dosing – Flash mixing Tank capacity – 1,000 liter. Quantity- 1(One) Material of construction- PVC Agitator mechanism- 1 (One) Motor- 0.75 KW, V-400, 3 P, 50 Hz RPM – 1000 RPM Origin- Bangladesh + India


21

Polyelectrolyte (PE-100 % purity) tank agitator.

22

HCL (Hydrochloric acid) dosing tank agitator mechanism

23

Nutrient (Urea & DAP) dosing tank agitator mechanism.

24

Activated carbon and sand filter feed Pump.

[

39

Location of dosing – Flocculation mixing. Tank capacity – 1,000 liter. Quantity- 1(One) Material of construction- PVC Agitator mechanism- 1 (One) Motor- 0.75 KW, V-400, 3 P, 50 Hz RPM – 1000 RPM Origin- Bangladesh + India. Location of dosing – PH correction mixing. Tank capacity- 1000 liter Quantity – 1 (One) Material of construction – PVC Location of dosing – Biological reaction tank. Tank capacity – 1,000 liter. Quantity- 1(One) Material of construction- PVC Agitator mechanism- 1 ( One ) Motor- 0.75 KW, V-400, 3 P, 50 Hz RPM – 1000 RPM Origin- Bangladesh + India. Type – Horizontal, Centrifugal/Sub Model- KSB/JOHNSON Capacity – 30m3 / Hr. Discharge pressure- 25 MWC Head – 16 MWC Motor- 7.5 KW, Volt-400, 3 P, 50 Z. RPM- 1450 RPM Quantity- 1 (One) Size- Suc. -80 MM Del.- 50 MM. Material of construction Body-CI Temperature – 80 0C Origin – India. With base frame, coupling, bolts etc


25

Pressure sand filter.

Quantity- 1 (One) Type- Down flow. Model- Aquatech sand filter. Diameter- 1,600 MM Height on straight- 1,800 MM Design pressure- 3.5 kg/cm2 Material of construction – Mild steel Treated flow rate- 30 m3 / Hr Deep of media- 900 MM Media fill- Sand media and Gravel support. Duty- Filtration.

26

Activated carbon filter

Quantity- 1 (One) Type- Downflow. Model- Aquatech sand filter. Diameter- 1,600 MM Height on straight- 1,800 MM Design pressure- 3.5 kg/cm2 Material of construction – Mild steel Treated flow rate- 30 M3 / Hr Deep of media- 900 MM Media fill- Granular Activated carbon support. Duty- Filtration.

27

Interconnection piping

Quantity- 1 (One) lot Butterfly valve, Gate valve, Elbow, Tee, Flange, Pressure gauge, Ball valve, Non return valve etc.

11.14Electrical Scope of Supply SR. NO 01 02 03 04

Items Glands for cables Motor (As required for the equipment listed in mechanical List) Crompton / Kirloskar/ China Main Distribution Board with MCCB, MCB, Ammeter, Voltmeter with selector switch, Indicator lamp, Overload relay with complete distribution board. Power cable from distribution board to different motor. 40

Unit 1 Lot 1 Lot 1 (One) 1 Lot


05 06 07

Local made Power cable from different motor to operating panel board Suitable cable tray made by M.S. angle & flat bar. Structural steel support for cable tray lying in the plant.

41

1 Lot 1 Lot 1 Lot


12. List of Appendixes Appendix-I

Description and Operation of Pressure Sand Filter & Activated Carbon Filter

Appendix-II Technical information about Pump Appendix-III Technical information about Air Compressor Appendix-IV Information about Painting

Appendix –1 Technical specification of Pressure Sand Filter and Activated Carbon filter. Pressure Sand Filter 1. No of unit 2. Type 3. Capacity at normal flow 4. Size of unit Diamater Height 5.Material of Construction

: One (1) : Cylindrical : 30 M3/hr : 1600mm : 1800mm : M.S : 2 kg/cm2

6. Pressure condition at Minimum working 42


Maximum working

: 3.5 kg/cm2

7. Painting details, Internal External 8. Support details

: Epoxy : At first red oxide and then epoxy : M.S construction built in four legs provided. 9. Manhole details, Number : One (1) Type : Circular Size : 450mm Material : M.S 10. Handhole details, Number : One(1) Type : Circular Size : 150mm Material : M.S 11. Supporting Bed Type : Graded Garvel Specification : (1½”- 1”, 1"- ¾”, ¾” - ½”, ½” - 1/8”, Mesh) Bed Depth :900mm 12. Pipeline details, Size Material Make End connection 13. Valve details

Size Type

:100 NB :M.S : Aquatech :Flanged :100 NB :Butterfly

Activated Carbon Filter 1. No of unit 2. Type 3. Capacity at normal flow 4. Size of unit Diamater Height 5.Material of Construction

: One (1) : Cylindrical 3 : 30 M /hr : 1600mm : 1800mm : M.S

6. Pressure condition at Minimum working Maximum working 7. Painting details, Internal External 8. Support details

: 2 kg/cm2 : 3.5 kg/cm2

: Epoxy : At first red oxide and then epoxy : M.S construction built in four legs 43


provided. : One (1) : Circular : 450mm : M.S : One(1) : Circular : 150mm : M.S : Graded Garvel and activated carbon : (1½”- 1”, 1"- ¾”, ¾” - ½”, ½” - 1/8”, Mesh) Bed Depth :900mm

9. Manhole details, Number Type Size Material 10. Handhole details, Number Type Size Material 11. Supporting Bed Type Specification

12. Pipeline details, Size Material Make End connection 13. Valve details

Size Type

:100 NB :M.S : Aquatech :Flanged :100 NB :Butterfly

Operation of Pressure Sand Filter & Activated Carbon Filter The filtration section mainly comprises of following equipment 1. Pressure Sand Filter (PSF) 2. Activated Carbon Filter (ACF) Water from Tube Settler II flows by gravity into the filter feed sump. This is almost treated effluent, which is then passed through the pressure sand filter (PSF) and then Activated Carbon Filter (ACF). Operation: The Plant is designed to provide trouble free service. Each of the above filter units needs to be backwashed once in 24 hour or whenever pressure drop across PSF and ACF reaches 0.7 kg /cm2 g whichever is earlier. 44


The Pressure Sand Filter & Activated Carbon Filters are backwashed in staggered fashion which is described below. Backwash of PSF The following steps to be followed Step-1 Air scouring of PSF Close inlet valve V1 and outlet Valve (i.e inlet valve V1 of ACF). Open the air scouring valve V6 & air vent valve V7. Switch on the blower and continue air scouring for about 5 minutes. Air scouring of PSF is done to ensure thorough backwash of the filter. Valve position Open V6 ,V7 Close V1,V3,V4,V5,V8,V9 [[[[[[[[[[[[[

Step-2 Backwashing of PSF Open backwash inlet valve V3 and backwash outlet valve V4 . Continue backwash of the filter for 8-10 minutes. Water during backwash flows in the upward direction thereby cleaning the filter off dirt accumulated at the top of the filter media . Backwash water comes out of backwash out let and same shall be drained . Flow rate for filter backwash shall be 60 m3/hr . Valve position Open V3 ,V4, V8 Close V1, ,V5,V6,V7, V9 Step-3 Rinsing of PSF Close backwash inlet & out let i.e. V3 & V4 and open service inlet valve V1 and rinse out let valve V5. Rinse water comes out of backwash outlet and the same shall be drained. Continue rinsing for 5 minutes. Rinse flow rate shall be same as service flow rate i.e. 30m3/hr. Valve position Open V1 ,V5 Close V3, ,V4,V6,V7,V8,V9 B. Backwash of ACF Step-1 Backwashing of ACF Close rinse outlet valve V5 of PSF, service inlet and outlet valve V1 & V2 of ACF. Open backwash inlet and outlet valve V3 & V4 of ACF. Backwash water flows in upward direction in 45


ACF thereby backwashing the media. Continue backwashing for about 10-15 minutes . Backwash water comes out from backwash outlet and the same shall be drained .Flow rate for ACF backwash 30 m3/hr. Valve position Open ACF V3 ,V4, V8 Close ACF V1, ,V2,V5,V6,V7,V9 PSF All the valve of sand filter close Step-2 Rinsing of ACF. Now close the backwash inlet & outlet valve V3 & V4 of the ACF . Open service inlet valve V1 of PSF and service inlet & outlet valve V1 & V2 of ACF rinse outlet valve V5. Continue rinsing for about 3-5 minutes. Rinse water comes out from backwash outlet and the same shall be drained. Flow rate for ACF rinsing 30m3/hr. Valve position Open Close

ACF V1 ,V5, V8 PSF only V1, V8 (All the other valve of PSF closed ) ACF V2,V3,V4 ,V6,V7,V9

Step-3 ACF in service mode. Valve position Open ACF V1 , V8, V2 all the other valves closed. For valve number refer interconnecting piping diagram of PSF and ACF

46


Appendix-II Technical information about Pump

47


Appendix-III Technical information about Air Compressor

48


Appendix-IV

Information about Painting

49

ETP MANUAL STD

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