The Indian Experience in Environment Management in Tanning Industry A. Sahasranaman Vice Chairman, CEMCOT, Chennai, India (Presentation made at the Innotech International Forum, Technology for Sustainability, Bologna, Italy on 20 Oct 11)1. I thank ASSOMAC for giving me the opportunity to share the Indian experience in environment management of the tanning industry. As you may be aware, the Indian tanning industry has come under sharp and constant scrutiny, first of the communities living around the tanning clusters and then of the Pollution Control Authorities and the Courts of law. Violations of pollution discharge norms by the tanning industry have been severely dealt with the Pollution Control authorities as well as the courts of law. On the other hand, the leading global brands, sourcing leather and products from India, insist on social and environmental compliance before agreeing to do business with Indian partners. All these developments have brought environment management in the tanning industry to the centre stage. Being a vast country, the situation varies from region to region. In this presentation, an overall picture of environment management in the tanning industry of India will be attempted.2. Indian tanneries process about 3000 tonnes of raw material per day. 80% of raw material processed by the tanneries is sourced domestically. Though, over the years, various efforts have been made to replace or reduce quantity of salt used for preservation of hides and skins, unfortunately, as of date, almost the entire raw material produced domestically is received in wet salted condition. This is the source of a major environmental challenge faced by tanneries today. India imports about 0.5 billion US dollars worth of leather, most of it as semi processed, wet blue, leather. The industry is found generally in concentrations; there are four such concentrations. Tamil Nadu in the south of the country accounts for about 50% of all tanning being done; Kolkata in the east, about 18%; Kanpur in the north, about 20%: and, Jullunder, further up north, about 7%. The rest of the quantity is processed in isolated pockets of the country. All the tannery clusters are found alongside major river basins. The Tamil Nadu clusters are either around river Palar or Bhavani. Kanpur is near the Ganges; and Kolkata is close to the backwaters of the sea.3. Some unique features of the Indian tanning industry from the point of view of environmental management deserve to be noted. The industry is populated by a large number of small enterprises, each processing raw material quantity ranging from 1t to 5t per day. About 40% of the industry’s output comes from well established large modern tanneries but the rest from small and medium enterprises. These small tanneries lack the financial, technical and managerial resources for setting up their own effluent treatment facilities. Also, many of them lack required space for the same. It has therefore become necessary for clusters of tanneries to get together and establish special legal entities, often companies, for setting up and operating common effluent treatment plants (CETP), to receive and treat the waste water to meet the discharge norms prescribed by the authorities. It may be interesting to note that India has at present 19 such CETPs, of which, 14 are in Tamil Nadu. The CETP in Calcutta Leather Complex in the east of the country is the largest, with a designed capacity of 30000 cubic meter per day, at present operating at a level of 20000 cubic meter per day. Apart from these ETPs, there are more than 150 ETPs, treating waste water generated by
large tanneries in the country. The total waste water produced by tanneries in the country is estimated at 100,000 cubic meter per day.4. In so far as the parameters as well as the limits prescribed against each parameter for different recipients are concerned, these are in line with similar limits adopted in most developed countries. The main parameters are BOD, COD, TSS, pH, TDS, Cl, SO4, Cr total, Cr6, N. There are specific limits established for surface, sewer, marine discharge and for irrigation. It has been the experience of CETPs and ETPs in India and elsewhere in the world that conventional effluent treatment systems are not capable of treating pollutants like Total Dissolved Solids, chlorides and sulphates. In some locations in India, this has emerged as a major challenge. TDS, chloride and sulphate norms are, however, not applicable if the treated waste water is allowed marine discharge or allowed to combine with domestic sewage of capacity that may offer adequate dilution.5. The O&M cost of the conventional CETPs operating in India varies from Euro 0.50 to Euro 0.80 per cubic meter. A significant feature of the CETPs in India is that within the premises of each CETP, a sufficiently large ‘secure land fill’ has been created into which the sludge generated by the CETPs is stored. This has obviated the need to pay a fee for disposal of such sludge on the one hand and at the same time, there is no transportation cost involved too. It is learnt that in Europe 40% of the cost of waste management is spent towards disposal of sludge.6. Depending on the nature of recipient, the Indian pollution control authorities have prescribed different set of norms for disposal of treated effluent. For example, in Calcutta Leather Complex, having the largest CETP, marine discharge norms are allowed because the treated effluent flows into a canal which, after a few miles downstream, joins the backwaters of the sea. Accordingly, the treated effluent is not required to meet discharge norms of TDS (2100 ppm), chloride (1000 ppm) and sulphate (1000 ppm). The Calcutta Leather Complex is a modern industrial area developed, close to the city of Kolkata, to relocate the tanneries scattered within the heart of the city of Kolkata. In Kanpur, the other major concentration in the north of India, with Dutch assistance, a large CETP of 36000 cubic meter per day capacity combined sewage and industry waste water (in the ratio of 3:1) treatment has been established at a location called Jajmau, adopting the UASB technology. This plant has the capacity to generate some electric power too. Here too, TDS etc norms are not insisted on. Though in other clusters in north India, surface discharge is resorted to, TDS, chloride and sulphate norms are not yet insisted on. However, in the south of India, Tamil Nadu, accounting for 50% of tanning in the country, the authorities have ordered that no tannery shall be allowed to discharge even a single drop of effluent to the surface. The reasons for this diktat are that the soil and ground water have been contaminated due to past discharge of high TDS effluent; also, Tamil Nadu, is suffering from chronic shortage of water, necessitating recovery and reuse of all industrial waste water. This has necessitated all the tanneries to either go in for their own waste water recovery systems or the CETPs had to take over such responsibility. The rest of this presentation will deal with how Tamil Nadu tanners have so far faced this challenge.7. The tanners realised that in order to set up complete waste water recycling, they would have to adopt the reverse osmosis technology followed by evaporation of rejects. The technology as well as financial resources required for such a mammoth task were beyond the capacity of the CETPs. Accordingly, groups of CETPs joined together to create special purpose vehicles, mainly large companies, to access technology and finances for setting up such plants, locally referred to as ‘Zero Liquid Discharge’ (ZLD) Systems. Two CETPs, one at Perundurai
(1000 cubic meter/day) and another at Melvisharam (600 cubic meter/day), have established ZLD systems on their own with some support from the Government of India, at a total investment of about 3 million Euros. These two systems have been operational for the last few months, by and large, successfully. The other CETPs have taken the help of two large companies, namely, AEDOL (Ambur Economic Development Organization) and CEMCOT (Chennai Environmental Management Company of tanners). While AEDOL has established three ZLD systems covering four CETPs, for treating a combined volume of 7300 cubic meter of waste water per day, CEMCOT is in an advanced stage of completing six such systems covering 7 CETPs for a combined volume of 13500 cubic meter of waste water per day. AEDOL has invested about 20 million Euros while CEMCOT is investing about 30 million Euros towards capital investment. Two of the systems established by AEDOL are under trial runs and the third one is under stabilisation; Of the six systems of CEMCOT, one is ready for commissioning and four others are to be commissioned by December 2011.8. The ZLD system is virtually a continuation of the conventional treatment systems. After secondary clarifier and tertiary treatment, the effluent is taken to a reactivator clarifier where softening of the effluent, as required, is done. It then flows to the multigrade filter before being fed into ultra filtration (UF) units. The output of UF units is taken to organic scavengers where remnants of organics are removed. The output of organic scavengers is generally found to be colourless, odourless and generally devoid of any contaminants except TDS, chlorides and sulphates. This is then fed into the reverse osmosis units. The permeate of the RO system is clean water, with TDS less than 500 ppm and chlorides less than 200 ppm. The reject of the RO system, about 25% of the volume, is then taken to the multiple effect evaporator where the water is evaporated and solid salt collected. The condensate of the evaporator is taken back to the permeate. In effect, almost 100% of the waste water is recovered in this process, because apart from the condensate of evaporators, the additional steam injected into the system to heat up the evaporator also adds to the volume of condensate. Typical values of parameters for raw effluent, after organic scavenger and of the permeate may be seen in the table below: Typical values of parameters at different stage of treatment S.No Parameter Raw After RO effleuent organic permeate scavenger 1. pH 8.5 6.5 7.0 2. Turbidity(NTU) 850 nil Nil 3. TDS (mg/l) 16000 16000 350 4. TSS(mg/l) 4200 nil Nil 5. COD(mg/l) 4750 125 Nil 6. BOD(mg/l) 1100 2 Nil 7. Total hardness 1600 420 1 (mg/l) 8. Chloride (mg/l) 9500 9400 1109. It is estimated that after all the ZLD systems operate in the state of Tamil Nadu to full rated capacity, the quantity of salt to be produced by these systems will be of the order of 450 tonnes per day. It appears that the Tamil Nadu tanners will soon become also producers of salts of different kinds.
10. Under Indian conditions, the approximate capital cost incurred for establishing these ZLD systems in existing CETPs has been found to be of the order of Euro 2500 per cubic meter. The O&M cost is estimated to be between Euro 2.5 and Euro 3.0 per cubic meter, almost four to five times the O&M cost of conventional treatment systems. Among the constituents of the cost of operation, energy (power and steam) account for 62%, chemicals 10%, manpower 8%, replacement cost 5%, capital cost repayment 15%. The critical factor for success of the RO system is to ensure that the effluent fed into the RO meet essential requirements with regard to organics and hardness. It is necessary to ensure that the organics are completely removed and hardness reduced to acceptable levels to avoid scaling of the RO membranes as well as of evaporator. Being a very sophisticated sytem, it is also essential that the monitoring and control of the operation and maintenance are diligent and efficient.11. With regard to the solid waste recovered from tanning operations, such as hair, fleshings, trimmings of raw, wet blue, crust and finished leather, shavings, etc. it has been found that in India all these are converted into some by products or the other, though not through advanced technologies. Fleshings and raw trimmings are converted to glue or dog chews; fleshings are also converted into animal protein. Hair and wool are used to make rough blankets. Trimmings of semi processed leather are converted into leather boards. Some demonstrations had been carried out, under the UNIDO’s Regional Programme for South East Asia (1996-2002) for producing methane from fleshings and sludge and compost from fleshings and other vegetable waste etc. but these have not been adopted widely. There is some scepticism about the compost produced as no agency is yet ready to certify its use for agricultural purposes. There is scope for introduction of more modern technologies for conversion of solid waste into by products.12. With the Indian experience so far, it has been possible to establish that technologically it is possible to recover almost 100% waste water for recycling in tanning industry. When tanners in other parts of India or other countries are not required to adopt such an expensive process of treatment, will it not put the tanners of Tamil Nadu at a great disadvantage vis a vis the price of material sold? It is a moot question. Some of the questions being dealt with are: (1) How to use or dispose the salt recovered by the ZLD process? (2) Is there any other means of utilisation or disposal of sludge than disposal in secure landfills? (3) How to reduce the O&M cost of ZLD systems? With regard to use of salt recovered, it has been found that the salt recovered from effluent of tanneries processing raw to wet blue, it has been mainly sodium chloride and it can be partially used for pickling and the rest of it recycled amongst the raw material suppliers to be used as preservatives. This manner, the salt loop can be completed. When the salt received is a combination of chloride, sulphats and carbonate, efforts are on to recover sulphates as these fetch good price in the market. IN so far as utilisation or disposal of sludge other than in secure land fill is concerned, India is looking forward to interesting suggestions and proposals from IULTCS and other international agencies. Experience of Italy will also be of great value. On O&M cost, though part of it is recovered as the tanners do not have to pay for the recycled water, yet, it is quite high compared to other tannery clusters in India or elsewhere in the world. Tanners are grappling with these challenges, hoping to find a solution sooner than later. How nice it will be if the buyers are ready to pay a higher price for such heightened standards of environmental management by these tanners!13. I thank you for your attention.