C A S E S T U DY

3 Background

Environmental profile

General Motors India Private Ltd The GMI (General Motors India) Private Ltd, part of the General Motors group worldwide, manufactures and markets passenger cars. The company has a single manufacturing unit located at Halol, Gujarat, where it has undertaken an environmental project for zero discharge from the plant and 100% recycling of the treated sewage waste water so as to conserve water. The GMI is committed to protecting human health, natural resources, and local and global environment in line with General Motors Corporation’s global environmental principles. These are based on integration of risk-based cost-effective management practices into site activities with the aim of continually improving environmental practices. The GMI has in place an environmental policy at both the corporate and facility levels. Separate cells exist for both the environment and health and safety. The GMI enjoys the distinction of being rated as one of the top three green-rated companies amongst the automobile companies in India. In accordance with the global common EPC (environmental performance criteria) to be followed and implemented by all GM plants worldwide, the Halol plant has a well-defined environmental system, which is in line with the requirements of ISO 14001 international standards. The company received this certification in July 2000. The GMI is in compliance with the EPC requirements, and implementation of the programme has resulted in better waste management practices (in both hazardous and non-hazardous wastes), water pollution control as well as resource conservation. All the company’s products are compliant with Euro II norms, which have a closed loop evaporation emission control system. The company uses CFC (chlorofluorocarbon)free refrigerants and environment-friendly pollen filters. The environmental programmes are implemented across the plant through a cross-functional team consisting of representatives from all departments and headed by environmental management representatives (vice-president level) appointed by the managing director. The GMI has always been an environmentally conscious and responsible corporate. The company had installed a most modern ETP (effluent treatment plant), with a high level of automation simultaneously with other manufacturing facilities in 1995/96. A huge storage tank with a capacity of 1300 m3 for retaining the treated waste water and necessary pumps and underground piping, with water sprinklers, were installed for supplying water for lawns and gardening as well as for green belt development. Thus the company had from inception designed the plant to be zero discharge facility. This initiative resulted in recycling of more than 15 000 m3 of water per annum as per current volumes. The other environmental initiatives undertaken by the company in the past are given below.

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General Motors India Private Ltd

Air pollution control The main sources of air pollution through process/flue gas exhaust stacks at initiative the plant were the paint spray booth, incinerator, hot water generator, fuel tank spray booth, and the oven burners. The company installed the latest high technology equipment, the latest production processes, and used LPG (liquefied petroleum gas) so as to minimize air pollution. It has in place various treatment methods like scrubbers and filters to further reduce air pollution. The major initiatives employed to reduce air pollution were the following. P Installation of a highly efficient automatic electrostatic bell painting system to reduce paint consumption and hence emission of fumes significantly. Initially, the company had started out with air spray guns, which had a transfer efficiency of 30% and 70% of the paint was wasted. With the introduction of the turbo bell electrostatic automatic painting system and electrostatic guns, the paint wastage was reduced from 70% to 30% and they had a transfer efficiency of over 90%. P By optimization of the area to be painted for fuel tank, the company reduced paint consumption and hence reduced fumes from the fuel tank painting booth. P Usage of LPG, a cleaner fuel, for all baking and combustion applications throughout the plant further reduced pollution.

Water pollution The main sources of waste water generation in the plant are the paint shop, RO prevention and (reverse osmosis) plant, cooling towers, softeners, and sewage waste water. The control initiative plant generates a daily average sewage waste stream of 50 kilolitres.

The process waste water from the paint shop is collected in separate lined RCC (reinforced cement concrete) sumps and is then transferred to the ETP. The waste water stream from the RO plant (30 kilolitres/day) has high total dissolved solids. It is partially taken to ETP and partially discharged into the retention pond, where it mixes with treated waste from ETP to meet the discharge requirements. For the cooling towers, a magnetic generator called Magnazen was developed in the US to eliminate or minimize chemical treatment of the cooling tower water. The company has been able to reduce the overall cooling tower blow-down to about 5 kilolitres/day. From inception, the company established a modern ETP with adequate facilities for treating all pollutants present in effluents. The plant has a high level of automation with necessary on-line instrumentation like pH controllers and conductivity meters. Manual intervention in the plant is kept to a minimum. The company undertook the following measures to combat waste water treatment. P The treated trade effluent was 100% re-used for gardening and green belt development. P The plant has laid out the necessary piping and pumps, etc. and other instruments for utilizing the treated sewage water along with the trade effluent. P The company replaced the chrome-based passivation process (paint preshop treatment) by a chrome-free zirconium process to eliminate chrome bearing waste. P It used an environment-friendly biodegradable solution for degreasing process in the entire pre-treatment. P The company adopted minor process modifications and other waste minimization practices, which resulted in reducing the waste water generation to 43 kilolitres/day (after 1999) instead of 65 kilolitres/day from the paint shop.

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Table 1

General Motors India Private Ltd

Controlling water pollution (in parts per million except pH)

Total dissolved solids Chemical oxygen demand Total suspended solids Ammoniacal fluid Biological oxygen demand Heavy metal pH (6.5 to 8.5) Sulphide Fluoride Phenolic compounds NA – not applicable

Gujarat Pollution Control Board’s permissible limit 2100.0 100.0 100.0 50.0 30.0 13.2 8.5 2.0 1.5 1.0

Actual 1994.00 55.00 34.00 3.00 13.00 0.98 7.80 0.47 1.49 0.36

Before treatment 2186.50 96.50 51.00 NA 60.00 75.00 7.90 NA 3.55 NA

Hazardous waste The GMI has installed a sludge drying bed to reduce hazardous solid waste disposal initiative by over 25% by weight, by removing moisture content. The hazardous waste is disposed of at a common secured landfill. The paint shop phosphate sludge and incinerator ash is disposed of in lined and sealed HDPE (high density polyethylene) bags whereas ETP sludge is disposed of in encapsulated form through sealed RCC pipes.

Energy conservation The GMI has implemented a formal energy conservation plan. The use of air initiative cascading principle helps reduce air cooling/heating requirements in different seasons. The operation of switching on/off of the heating, ventilation, and air-conditioning system has been automated. All motors running below 80% load have been replaced. As a result of the above efforts, the electricity consumption per car produced came down from 1320 kWh in 2000 to 1183 kWh in August 2001, a saving of 10.4%.

Case study

The GMI has always laid stress on water conservation. From inception itself, the plant was designed for a complete closed water system in a way to completely treat and recycle trade effluent and completely treat and dispose of domestic sewage through a conventional septic tank and soak pit process. A modern ETP, with a high level of automation, was installed in 1995/96 and a storage tank of capacity 1300 m3 was installed for retaining the treated waste water. All the necessary piping and water sprinkler systems were installed so that the plant was a zero discharge facility right from the beginning. Subsequent measures like introduction of a closed loop DI (deionized) water circulation system helped save 20 kilolitres water per day; a modified phosphating process reduced DI water consumption by more than 10 kilolitres/day; installation of Magnazen minimized cooling blow-down and saved 24 kilolitres/day. With the domestic waste water being as much as the trade effluent, in 2001 the GMI adopted an innovative approach for 100% recycling of modified sewage water. After evaluation of various treatments, it concluded that a joint treatment for trade and domestic effluent would be the best techno-economic solution. It provided anaerobic treatment to domestic waste water in the same septic tank for major sludge removal, and transferred the supernatant to ETP to mix with primarily treated common stream of trade effluents in the final effluent sump.

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General Motors India Private Ltd

Flow diagram of effluent treatment system

Then the combined stream of effluent (trade and domestic) was provided with secondary biological treatment and tertiary treatment in the existing ETP facilities. The combined treated water is transferred to irrigation pond from where it goes for lawns/green belt development through the piping network. The management has laid down all the transfer pumps, long piping, cabling, control panel, instrumentation, and septic tank modifications for this facility. Primary chemical treatment is given to various streams to remove the heavy metals present in it. The primary treated waste streams are collected in a common final effluent sump and this common stream is given a secondary – biological – treatment. This removes/reduces biological oxygen demand and chemical oxygen demand load. Tertiary treatment to remove any residual solids, using the Dyna sand filter, is also provided. The filtered effluent is collected in the guard pond where it is tested and then pumped into the retention pond to be used for gardening and green belt development. This modified sewage system has resulted in recycling of over 18 250 m3 of water annually in addition to 15 000 m 3 due to trade effluent. The recurring cost savings achieved on account of reduced energy consumption associated with the use of recycled water was 69 400 rupees per annum. The key drivers for programme adoption were a water shortage faced by the GMI for lawns/green belt development area, because of the vast area covered. Also, during summers, the yield from the tube wells was very low to almost nil. The company had to resort to buying water in some cases. The approach adopted was to do a thorough treatablility and feasibility study to find out the best and most viable treatment system to modify the sewage/domestic waste water. The study was conducted by a professional environmental agency and on whose recommendations laboratory tests were conducted to put in a modified treatment process. The main challenges faced were in terms of the timing of outlay for the programme, which coincided with a general recession in the company’s business segment of premium cars.

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General Motors India Private Ltd

Process flow diagram

The payback period was kept to a minimum as the company used the services of a professional environmental agency, which recommended the course of action, after which the management approval was obtained for implementing this initiative. All the necessary facilities such as transfer pumps, long piping, cabling, and septic tank modification were set up later. Rigorous practical trials were done over 30 days to ascertain that the combined stream was getting the required treatment and that all the parameters were meeting the discharge standards. The revenue generation potential of the project stems from the ease of transferability to other industries, which face a water shortage, as well as the non-prohibitive cost of implementation and quicker payback in terms of returns and lack of business interruptions.

Case study at a glance The technical facets covered by the project are as follows. P In 2001, the GMI (General Motors India) adopted an innovative approach for 100% recycling of modified sewage water. It concluded that a joint treatment for trade and domestic effluent would be the best techno-economic solution. P It provided anaerobic treatment to domestic waste water in the same septic tank for major sludge removal, and transferred the supernatant to effluent treatment plant to mix with primarily treated common stream of trade effluents in the final effluent sump. P Primary (chemical) treatment is given to various streams to remove the heavy metals present in it. P The waste streams from primary treatment are collected in a common effluent sump for secondary (biological) treatment. This removes/reduces the load of biological and chemical oxygen demand. P Tertiary treatment of effluent removes residual solids, using the dyna sand filter. The filtered effluent is collected in the guard pond where it is tested and then pumped into the retention pond to be used for gardening and green belt development. P The combined treated water is transferred to irrigation pond and used for watering and green belt development through a network of pipes. P Modification of the sewage system resulted in recycling of over 18 250 m3 of water annually in addition to 15 000 m3 of trade effluent. P The recurring cost savings achieved on account of reduced energy consumption associated with the use of recycled water was 69 400 rupees per annum.