COMPARATIVE ANALYSIS OF MULTIPLE EFFECT EVAPORATORS AND ANAEROBIC DIGESTER (UASB) FOR AN EFFECTIVE MANAGEMENT OF RO REJECT FROM TANNERY

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1 International Journal of Civil Engineering and Technology (IJCIET) Volume 8, Issue 4, April 2017, pp , Article ID: IJCIET_08_04_094 Available online at ISSN Print: and ISSN Online: IAEME Publication Scopus Indexed COMPARATIVE ANALYSIS OF MULTIPLE EFFECT EVAPORATORS AND ANAEROBIC DIGESTER (UASB) FOR AN EFFECTIVE MANAGEMENT OF RO REJECT FROM TANNERY Gangarapu Hareesh Department of Civil Engineering, SRM University, Chennai, India Sija Arun Assistant Professor, Department of Civil Engineering, SRM University, Chennai, India Dr. P. Shanmugam Senior Principal Scientist, Department of Environmental Science and Engineering, CSIR-CLRI, Chennai, India ABSTRACT The world without leather product we can t expect since all are adjusted in comfort zone in leather. In the process of producing leather lot of chemical are used and also some vegetable products. The effluents from tannery having high COD, BOD, Solids in both Suspended and Dissolve states and Nitrogen related products. The treatment process implemented in plants is recovered all the chemicals and removes Chromium from the effluent. The development in a sustainable manner ZLD system was introduced in Industries. ZLD implemented RO system in treatment in plants which can Water without any color and solids, and reject with high salt content as dissolved solids. The reject required to treat in economically suitable ways. The existing treatment methods are mechanical and anaerobic like evaporation and UASB reactor. The MEE systems are popular and used in all parts of the world in treating saline water to make it potable to overcome water demand and also to treat the wastewater by evaporation solidify/condensate to decrease the volume. In UASB the water with pollutants is passed through the blanket of sludge for degradation of solids present in the waste wit help of micro-organism on the outer surface of the granule. In anaerobic digestion, we can get gas having a high percentage of methane gas which can help us produce electricity at low cost. Key words: Reject/brain, Digestion, COD, BOD and Evaporation editor@iaeme.com

2 Gangarapu Hareesh, Sija Arun and Dr. P. Shanmugam Cite this Article: Gangarapu Hareesh, Sija Arun and Dr. P. Shanmugam, Comparative Analysis of Multiple Effect Evaporators and Anaerobic Digester (UASB) for an Effective Management of RO Reject from Tannery. International Journal of Civil Engineering and Technology, 8(4), 2017, pp INTRODUCTION Leather industry has very important role in the economies of countries like India, Bangladesh and china etc. [1] [2]. Annual leather production is 2109 M mt2 approximately and annual trade estimated as 100 billion American Dollars [3]. Indian tannery is one of the largest industries in the world and also having a great importance in the economy. India produces 10% (180 million square meters) of global leather production [4] Tanning Process Effluent Properties Tanning (the process of leather production) is carried with around 300 chemicals in different stages namely soaking, fleshing and trimming, deliming and batting, pickling, degreasing and tanning (chrome tanning and vegetable tanning) and involves a lot amount of water and along with following at each stage of the process [5]. Sorting is the skins and hides collected are sorted based on size, weight and quality. Curing & Storage is the process of preventing the degradation of hides and skins. Based process period the curing involved, like salting, brining, drying, salt drying and cooling. Soaking is the method of allowing hides and skins to reabsorb the water. In this process the hides and skins are cleaned from dung, blood and dirt. It carried out in two different way, one for removing dirt and salt and another is main soak. This process requires detergents, enzymes, and biocides and gives effluents like salt, BOD, COD. SS, DS, and Organic N. Unhairing and liming helps to remove the hair, epidermis, and some protiens to prepare skin for adhering flesh and fat by fleshing process which involve lime, sulfides and enzymes and effluent with BOD, COD, SS, DS sulfides organic N ammoniacal N are generated. The removal process of excessive organic matter from hide using mechanical scrapping is fleshing, produce effluent with high COD value. Deliming removing lime or alkali from skinits done based on final leather type and batting is removal of hair roots and pigments which not happened in unhairing process. The deliming and batting results effluent with major portion of NH 3 load in effluents. Degreasing is the process of removing fat which may gave problem with uniform penetration of tan and dye. It consumes agents for deliming, enzymes, surfactants, solvents and enzymes and reject with BOD, COD, DS, ammoniacal N and fat/grease, and solvents. Degreasing is done by organic solvents or surfactants leading to higher COD value in the effluent. Picking is carried for reducing the ph prior to tanning. Tanning is process of stabilizing the collagen fibres, common tanning agent is basic Chromium Sulphate. Salt, acid, chromium, aldehyde, vegetable are used in pickling, tanning and followed by samming (reducing moisture content by squeezing) results BOD, COD, DS, salt, acidity, chromium, aldehyde, vegetable tans and syntan. The pickling stage increases acidity by adding acid and salts for preventing the swelling. Retanning Dyeing Fatliquoring requires vegetable chromium, dyes result in effluent with BOD, COD, DS, chromium, vegetable tans, syntan, dye, and fat [7] editor@iaeme.com

3 Comparative Analysis of Multiple Effect Evaporators and Anaerobic Digester (UASB) for an Effective Management of RO Reject from Tannery 1.2. Treatment Process The treatment process involves from pre-treatment, mixing, aeration, primary sedimentation, and secondary sedimentation and followed by neutralization and filtration. Pre-treatment consist of screening and aeration based on the quantity of waste. By adding chemicals like alum and lime for flocculation and minimum of 24 hours retention time. Primary sedimentation involves flocculation and clarifier with suitable retention time. The process can be accelerated by sludge recirculating. After sedimentation water is pumped to dual media filters with pressure filtering mechanism having coal with sand and gravel. All these processes result in the water with colour and TDS [8] Zero Liquid Discharge System Advancement in technology results in sustainable development in all the places. In industries, it renamed as Zero Liquid Discharge. It means the liquid coming out from industries to be zero, i.e, treat waste produced and use it again or release effluent without harmless to the environment. To achieve ZLD in tannery industry the technology of RO is introduced, which is giving a great result in removing the solids, color, and metals. But the problem is the RO process gives 33% of reject containing high solid content, BOD, and COD, which needs further creates disposal problems since it has no proper process of disposal method been identified in order to water bodies as well as soil surface from pollution or contamination. Figure 1 RO Process 2. WAYS TO HANDLE RO REJECT Cleaning of reject coming out of RO plant is part of ZLD, It follows 2.1. Multi Effect Evaporator (MEE) Apparatus use heat in vapour to evaporate the water. In multi-effect evaporator, the water is boiled in vessels connected in sequence at different pressures from higher (beginning) to lower (end of the system). The reason behind the arranging lower pressure is water boiling temperature decreases with the decrease in pressure. The vapour liberated at one stage is transferred to another stage so the vessel with higher pressure needs the heat source from external. Based on the treatment method the stages/ drop in pressure are installed in the editor@iaeme.com

4 Gangarapu Hareesh, Sija Arun and Dr. P. Shanmugam system. From four stages to seven stages of evaporators available, the seven stage evaporator used for chemical recovery from liquor [6]. These are mainly designed for concentrating the sugar can juice. But due to demand in water and as well as salt the same system is introduced in desalinisation which can give both the water for drinking by condensation of vapour and as well as salt [6]. Figure 2 Multi Effect Evaporator System MEE is evaporation methods which are maintained at different pressures (effect). The water vapour is formed by the exchange of heat with boiled water; same is repeated continuously from higher pressure to lower pressure. In this method, the product and steam are passed into the evaporator at a time and as a results vapor from the top, the product from bottom and condensate at the same level of feed. This process reduces the wastewater up to 40% in volume from actual [4]. Evaporators available in all sizes and shapes falling film-, rising film-, forced circulation-, scraped surface/thin film- and combination evaporator Up- Flow Anaerobic Sludge Blanket Reactor One of the anaerobic processes forms a sludge blanket in suspension state inside the reactor. The effluents are passed through the blanket from bottom to top and degraded by the microorganism which formed in the anaerobic state. The flow and settlement action are occurred parallel by gravity. Blanket requires around three months time for maturity. The surface areas of the granular particle are covered by bacteria [10]. The microorganism is accumulated in the blanket, which helps to degrade the feed from the bottom of the digester with a velocity of suitable hydraulic retention time. The velocity will help in both the ways that as feeding and to make the gas to move out from the blanket. The gas is separated from the solids and liquid at the top provided with a dome-like structure named as the gas-liquidsolid separator [11] editor@iaeme.com

5 Comparative Analysis of Multiple Effect Evaporators and Anaerobic Digester (UASB) for an Effective Management of RO Reject from Tannery Figure 3 UASB Reactor The gas with methane in large percentage is captured as the by-product and used as fuel to generate electricity for exporting and running of feed pump consumption [9]. The sludge blanket is to be maintained from washing for continuous generation of biogas as well as electricity. The same electricity generated from the gas can be reused for produce heat required for the digestion process. The rate of digestion remains constant in the reactor for 90 days. The process is accelerated if any sugar content presence in waste will be converted to the gas within the day. These are suitable of digesting the waste waters having 3% of TSS with the size of particle >0.75mm. 3. RESULT AND DISCUSSION 3.1. Multi-Effect Evaporator System RO reject contains a lot amount of salt that s the reason it has been called as hyper saline wastewater since the chemical added in tanning process are removed at treatment steps except the salts in form of dissolved solids. The feed parameters of RO reject is effect the efficiency of evaporator [13]. The evaporator can treat the waters contains up to ppm, only thing is required a large amount of heat and the fuel for consumption [14]. Based on the solid concentration the amount of land used for evaporation is increased and the cost also increased for both maintenance of evaporator and also for the forest wood or gas as fuel. One of the studies mentioned that evaporation by using electric power and diesel will cost 180 Rs and 3430 Rs for treating of 1000 litres of the load editor@iaeme.com

6 Gangarapu Hareesh, Sija Arun and Dr. P. Shanmugam 3.2. Up-Flow Anaerobic Sludge Blanket Reactor UASB can treat any type of wastewater irrespective of origin. The digestion is done with help of microorganism accumulated at bottom of the tank in sludge blanket formed by gravity settlement of the seeding material Recent studies showing 60 to 90 % BOD, 60 to 80% of COD and 60 to 85% of TSS reduction [12]. It can give good results at a minimum of 2 hours HRT but, in general conditions, we run the reactor at 4 to 20 hours HRT. Its investment cost is very low when compared with other treatment options but, required skilled staff for maintaining organic load and adjusting the HRT with help of feeder pump. [15] 4. COMPARISON BETWEEN MEE AND UASB Table 1 Comparison Between MEE and UASB S.No. Characteristics MEE UASB [15] 1 Principal Feeding vapour into vessel along with vapour at different stages (pressures). 2 Size, shape & material Based on the quantity of waters availability suitably metal body with resist to scale formation coating. Passing through blanket of sludge at the bottom and separating gas liquid and solids at the top. Based on quantity and solid load. Concrete construction or metallic body. 3 Cost The huge initial cost for both installation and fuel. Comparably less cost and need energy for running feed pump. 4 Capacity Equally proportional to quantity. Based on HRT adjustment. 5 Performance More than 90% removal of solids. 60 to 90 % BOD, 60 to 80% of COD and 60 to 85% of TSS reduction [12]. 6 Compatibility The material need to import or extra arrangements like scale proof required. 7 Operation & Easily operated with or without the Maintenance skilled person. Can be constructed with locally available material. Required skilled person for operation and maintenance. 8 Strength Accurate result can get at any season. Little land required, removal efficiency 9 Advantage We can reduce the volume of waters in the greater level. 10 Disadvantage Consumes high amount of wood as fuel. is high and we can recover biogas. With small technical help, we can produce electricity and same can be used for feeding pump running. Smell problem and temperature need to maintain. 5. CONCLUSION ZLD is advanced technology to treat wastewater. By this, we can recycle recover and reuse the waters/ we can dispose of anywhere since it won t have any harm in nature. The method MEE and UASB gives good results in treating. But the UASB is quite economical easily maintainable. In places of a cold environment and high availability of fuel, we can implement the MEE, since UASB may not give proper results in all temperatures. In UASB by recirculating the same effluent will reduce the high quantity of solids/cod. The both MEE and UASB help us to control the pollutant concentration as well as the effluent volume editor@iaeme.com

7 Comparative Analysis of Multiple Effect Evaporators and Anaerobic Digester (UASB) for an Effective Management of RO Reject from Tannery REFERENCES [1] Chowdhury M, Mostafa MG, Biswas TK, Saha AK (2013) Treatment of leather industrial effluentsby filtration and coagulation processes. Water ResourInd 3:11 22 [2] Wang K, Li W, Gong X, Li X, Liu W, He C, Wang Z, Minh QN, Chen C-L, Wang J-Y (2014) Biological pretreatment of tannery wastewater using a full-scale hydrolysis acidification system. IntBiodeterior Biodegradation 95: [3] UNIDO (2010) United Nations Industrial Development Organization (UNIDO): future trends in the world leather and leather products industry and trade, Vienna. [4] Satish (2016) Disposal of Reverse Osmosis Reject Water for Achieving Zero liquid Discharge (ZLD), IJIREM [5] [6] [7] [8] A. Sahasranaman, K. V. Emmanuel (2011) Common Effluent Treatment Plant Pallavaram, Chennai, India, UNIDO [9] Efstathio K. Papadimitriou and Edward I. Stentiford (2004), TheArrowBio Process for Mixed Municipal Solid Waste (MSW). [10] Lettinga G (1995). "Anaerobic digestion and wastewater treatment systems". Antonie Van Leeuwenhoek. 67 (1): [11] Shalu, Narsi R. Bishnoi (2016), A Review on Up flow Anaerobic Sludge Blanket Reactor used in Wastewater Treatment, IJRMST [12] Dr. Tarek Elmitvalli (2005) Treatment of Municipal Wastewater in Upflow Anaerobic Sludge Blanket (UASB) Reactor %20Treatment%20of%20Municipal%20Wastewater%20in%20Upflow%20Anaerobic%2 0Sludge%20Blanket%20UASB%20Reactor.pdf [13] [14] Fredrik Tillberg (2004), ZLD-systems An Overview ( ) [15] treatment/hardware/semi-centralised-wastewater-treatments/u editor@iaeme.com