Water use is increasing and it is industry that is taking it up
Increasing water use is a fact of life in many countries and an inevitability for others. The world’s six billion inhabitants are already appropriating 54 per cent of all accessible freshwater reserves. It is predicted that by 2025 humankind’s share will be 70 per cent. This estimate reflects only the impact of population growth. A worse scenario looms large as the scramble for water intensifies.

Industrial water use is closely linked to the economy of a country. So far as India is concerned, as GDP increases, so will industrial water consumption

Who consumes water most? Households? According to UNDP’s World Water Development Report, 2003 (WWDR, 2003), they account for only eight per cent of global water consumption. The agricultural sector? It is the largest user of water globally and accounts for about 70 per cent of the total freshwater abstraction. However, it is predicted that both these users will be outdone by industry: Water consumption by industries is increasing. In fact, in high income countries, industrial water use already accounts for as much as 59 per cent of the total fresh water consumption; almost twice the amount used in agriculture. (See graph: Water use worldwide). It is likely, then, that this will become a global trend even as more and more nations begin to choose industry over agriculture, as a key to economic growth.

Growing need, growing concern
Presently, industry accounts for 22 per cent of the global freshwater consumption. It is expected that the figure will double over the next two decades. According to forecasts published in WWDR, 2003, the volume of water consumed per year by industry will rise from 752 km3/year in 1995 to an estimated 1,170 km3/year by 2025.

And where is this most likely to happen? Most of this increase in industrial water use in likely to happen in fast growing developing countries like India. There has been a significant migration of manufacturing industries from developed countries to developing ones and this trend is likely to continue. This will contribute to the increasing use of water by industries in developing countries.

Industrial use of water has a direct bearing on the country’s economy. This means that as India increase its GDP, there will be a corresponding increase in water use by Indian industries.

Industries not only consume water but also pollute it. According to the WWDR 2003, in developing countries, 70 per cent of industrial wastes are dumped without treatment, thereby polluting the usable water supply. Therefore, the issue of industrial water use revolves around two crucial interlinked issues — water use and water pollution.

As it is, water’s scarce
From a per capita annual average of 5,177 cubic metre in 1951, fresh water availability in India dropped to 1,820 cubic metre in 2001. In fact, it is predicted that by 2025, per capita annual average fresh water availability will be 1,340 cubic metre approximately. Already, the potential of most river basins is being exploited beyond 50 per cent and several basins are considered to be water scarce. Over 80 per cent of the domestic water supply in India is dependent on groundwater. However, groundwater is fast depleting. Water tables have fallen significantly in most areas and there is a significant pollution of groundwater from natural as well as manmade sources.

As it is, everyone is fighting
Agriculture receives the greater share of the annual water allocation in India. According to the Union ministry of water resources (MoWR), 80 per cent of India’s utilisable water is devoted to this sector, mostly in the form of irrigation. Demand from the domestic sector has remained low and accounts for only 5 per cent of the annual freshwater withdrawals in India. The industrial sector is the second highest user of water after agriculture. But we do not know how much water industries in India consume. (See table: Industrial water use...)

How much water does Indian industry consume?
The estimations of national and international agencies on industrial water use in the country vary significantly.

According to MoWR, industrial water use in India stands at about 40 billion cubic meters or nearly 6 per cent of total freshwater abstraction.

According to the Central Pollution Control Board (CPCB), in 2000, India’s annual fresh water withdrawals were about 500 billion cubic meter and the Indian industry consumed about 10 billion cubic meter of water as process water and 30 billion cubic meter as cooling water. Therefore, according to CPCB data, the water consumption in Indian industry accounts for about 8 per cent of the total fresh water use in the country.

According to the World Bank, the water demand for industrial uses and energy production will grow at a rate of 4.2 per cent per year, rising from 67 billion cubic meter in 1999 to 228 billion cubic meter by 2025. Therefore, according to the World Bank the current industrial water use in India is about 13 per cent of the total fresh water withdrawal in the country.

Despite differences, the estimates on industrial water use by the three agencies have a point in common. All the three agencies concur that industrial water use is growing at the fastest pace in the country.

To use or to misuse
That is the question industries need to think over

Water use in industry is a double-edged sword. On one hand it puts immense pressure on local water resources. On the other, wastewater discharged from the industry pollutes the local environment. Water is required, often in large volumes, by industries as process inputs in most industries. In other cases, like food and beverage and chlor-alkali industry, water is used as a raw material: turned into a manufactured product and exported out of the local water system.

However, in most industries it is essentially used as input and mass and heat transfer media. In these industries a very small fraction of water is actually consumed and lost. Most of the water is actually meant for non-consumptive process uses and is ultimately discharged as effluent.

Quantity and quality
The amount of water available matters but so also does its quality. Industry requires water of good quality for its use, and for this it uses cleaner upstream water. However, the water it discharges is always of lower quality than the feed water and this wastewater is discharged downstream. At best the wastewater discharged represents a quality that can be recycled for lower grade of industrial use and at worst represents water quality which is unsuitable for every use other than navigational puposes. In other words, this water is unfit for usage, is seldom used by the industries and usually used for certain agricultural purposes or by villagers to meet their daily needs.

Major consumers
Water consumption depends on the type of industry. Whereas thermal power, textiles, pulp and paper and iron and steel are highly water intensive sectors, industrial sectors like chlor-alkali, cement, copper and zinc and plastics require little water.
Data on actual water consumption in India is absent. However, the data on wastewater discharge by various industrial sectors in the country is available. The data on wastewater discharge has been complied by CPCB. According to CPCB, the total wastewater discharged by all major industrial sources is 83,048 million litres per day (mld). This includes 66,700 mld of cooling water discharged by thermal power plants (TPPs). Out of the remaining 16,348 mld of wastewater, TPPs generates another 7,275 mld as boiler blowdown water and overflow from ash pond.

Is it possible...
In the absence of data on actual water consumption is it possible to chalk out a water consumption pattern for Indian industry? The Centre for Science and Environment (CSE) has attempted to arrive at an estimate based on the wastewater data of CPCB.

According to CPCB the annual water consumption in Indian industry is 40 billion cubic meters and the annual wastewater discharge is about 30.7 billion cubic meter. Therefore, the overall ratio of wastewater discharged to freshwater consumption in Indian industry works out to be about 0.77. That is, for every cubic meter of water consumed by Indian industry, 0.77 cubic meters of wastewater is discharged. Considering this, CSE has estimated the possible water consumption in various industrial sectors in India.

Guzzlers: Inefficent water use by industry
The ratio of water consumption and economic value creation in Indian industry is poor. For every cubic metre of water that Indian industry uses, it generates merely US $7.5 economic productivity

Thermal Power Plants (TPPs): Most TPPs in India are owned by the government. Indian TPPs are one of the highest consumers of water as compared to their global counterparts. On an average, for every 1000 Kwh power, Indian TPPs consume as much as 80 cubic meters of water. The water consumption in the modern TPPs in developed countries is less than 10 cubic meters for every 1000 Kwh. The major reason for this atrocious figure is the widespread prevalence of 'once-through cooling systems'.

Pulp and paper: Water consumption in Indian pulp and paper industry is significantly higher than in developed countries:

- Complete discharge of paper machine wastewater, which can be recycled easily.

- Use of chlorine-based bleaching technology in wood and non-wood based mills. Due to the presence of chlorine compounds in the bleach wastewater, it cannot be used as 'black liquor' for energy generation and hence is discharged.

Textiles: The textile industry in India guzzles double the accepted amount for consumption.Why is this so? A major factor is obsolete technology which permits minimum recycling and reuse of process water. For instance, most textile mills in India do not use counter-current washing systems; instead they use clean water at every stage of the wash cycle. Similarly the reuse of final rinse water from dyeing for dye bath make-up or reuse of soaper wastewater, is absent in most mills.

Iron & Steel: The Iron & Steel sector is also water intensive industry. In India, approximately 80-85 per cent freshwater consumed in this sector is discharged as effluent. In contrast, in USA over 95 per cent of the water used for steel production and processing is recycled. Consequently, while the Indian steel companies consume about 10-80 cubic meters water to produce a single tonne of steel, in the US only 5-10 cubic meters of water is needed. Global best practice for wastewater discharge in integrated iron and steel plant is less than 0.1 cubic meter per tonne steel (See tables: Inefficient water use...; Comparatively very poor). Indian industry will have to reduce its voracious appetite for water. Water, the once inexhaustible natural resource, is going to be one of the most important factors to decide the growth and development of Indian industry in the future.

Water fall-outs
Industrial water use has triggered off a host of problems In developed and developing countries alike, competition among water users is increasing. Tensions are particularly high in water-scarce areas where domestic, agricultural and industrial water needs are pitted against each other. In developing countries like India, where every segment of the economy is growing rapidly, the conflict will become unmanageable if not addressed now. Even today most big cities in India are getting piped water from far-off places. This is putting tremendous pressure on the local population whose water is being snatched to feed urban and industrial growth.
This practice, also known as the "zero sum game of water management", is one where authorities increase water supply to one user by taking it away from another. This practice almost invariably leads to discontent in the different parts of the country.

Industry-community conflict
A major outcome of increasing industrial water use has been the increase in conflict between local communities and the industry on issues ranging from water pollution to water scarcity. In areas where there is water scarcity, industries are under tremendous pressure from community and government alike to reduce water use.

Depletion of groundwater by industries, supply of water meant for irrigation to industries, preferential treatment given to industries by the government are some of the major reasons for the conflict between industry and community over water use.

Another major reason for this ongoing conflict is water pollution. Protest and public interest litigations have become quite common on this issue.

Water scarcity
It is a bottleneck for industrial development in the various states of India

In 2002, companies like Harihar Polyfibres Limited, Karnataka and the Indian Rayon plant, Nagda shut shop for a few days. Inducing them to take such a step was the non-availability of water.

Water scarcity is already taking its toll on industrial production. In summers, when most Indian rivers run dry, it is not uncommon to see companies closing shop.

In a study undertaken by the Confedaration of Indian Industry and the World Bank in 2003, to find out what constituted good investment climate in various parts of India, it was found that water availability is one of the major infrastructural bottlenecks companies in Tamil Nadu face. The study covered 1,099 manufacturing companies in four sectors - textiles, garments, consumer electronics and pharmaceuticals - in 10 states and listed water as one of the major bottlenecks for future industrial growth in the country.

Indian industry can no longer ignore water management issues if they are to grow and become globally competitive.

Wherever there is conflict, a commmunity suffers. So does industry

SIV Industries
One of the few integrated viscose rayon manufacturers in India, SIV Industries was established in 1964. It is situated upstream river Bhavani in Sirumugai village of Coimbatore district, Tamil Nadu. The mill used river water and discharged its treated effluent back into river Bhavani.

Villagers living downstream used the water for drinking, irrigation and other household activities. They lodged complaints such as discoloration of water, skin allergies and a decline in crop productivity due to the usage of contaminated water.

The Bhavani river agitation was marked with protests by the local community mobilised by NGOs - Bhavani River Protection Joint Council and Lower Bhavani Projects Ryots Association.

Following the wide-scale protests by the local community as well as the directives of the Pollution Control Board and the High Court, the mill invested substantially to upgrade its pollution control equipment. It imported technology from a foreign agency (Linde, Germany) specifically for effluent treatment. The mill also started discharging its wastewater into its own land for the irrigation of crops.

But this entire episode took its toll and the industry is currently not operational.

Sinar Mas Pulp and Paper Mills Ltd.
Sinar Mas Pulp & Paper (India) Ltd. (SMPPIL) was set up in 1997 on the Pune-Solapur highway near Pune, Maharashtra. The mill met its entire requirement from Ujjani dam. Since the imported pulp is dry, SMPPIL consumed a large quantity of water during its papermaking process and the treated effluent was discharged through a 12 km long pipeline into river Nira.

The local communities in and around the region were against the mill for various reasons. To begin with, the water from Ujjani dam was originally meant for irrigation of drought-prone areas. Secondly, there was the fear that usage of water by Sinar Mas would lead to water shortage for sugarcane growers in Solapur and Indrapur, which in turn would affect the sugar co-operative factories.

To make matters worse, the local community was also upset at the preferential treatment given to the industry by the government, namely, cheaper rates for tankers (it was alleged that the government was charging only Rs 3 per 10,000 litre tanker from the company whereas farmers and villagers had to pay about Rs 100 per tanker). The industry was also assured that they would be provided water from the dam for eight months. But villagers received no such assurance.

As a spillover of this conflict more than 20 cases were filed against the company in various courts. The company thereafter reduced its water consumption significantly and today it is one of the lowest water-consuming paper mills in the country. It took almost five years for the company to regain confidence of the local community.

Currently the mill is functioning under the name of Ballarpur Graphics Paperboards Ltd.

Grasim Industries (GIL) - Mavoor Unit
The Mavoor unit of Grasim Industries is situated on the banks of river Chaliyar in Kozhikode district of Kerala. The unit produced rayon grade pulp. The unit used to discharge its treated effluent into river Chaliyar. Over 200,000 people live on the banks of the Chaliyar and the discharge of effluents by the mill was one of the main reasons of conflict between the local community and the mill.

Complaints of pollution of river, fish deaths and lack of adequate treatment facility at the unit began pouring in. There were also several health related complaints, such as high incidence of cancer in the region.

The mill failed to lay down a pipeline to Chungapally (seven km downstream) to discharge its effluents directly into the estuary area, as per its agreement with the state government in 1974. Several complaints were also lodged against the mill with the local pollution control board, and at various forums. Finally, due to prolonged public agitation in the area, on May 5, 1997, the government of Kerala formed a committee to study in detail the pollution problems caused by the industry and recommend solutions.

The committee made 28 recommendations after conducting a detailed study and interacting with the local community. The government accepted them and Kerala State Pollution Control Board gave time-bound directions to the mill in July 1998 to implement the recommendations within one year.

Instead, the mill decided it was time to close down.

Just use it
Poor laws and regulations and lack of coordination between regulatory bodies worsen the water crisis. There is no concrete government policy on industrial water use. The existing policies are merely a atchwork of public health and water availability concerns.

Regulating use

GLOBAL: Countries across the world set water consumption standards and targets for industries to achieve, and regularly revise the standards in a bid to control water use. China, for instance, sets water targets for major water consuming industrial sectors. According to the report of China Water Conservation Agency, the first national quotas for industrial water consumption will push companies to save as much as 6 billion cubic meters of water a year by 2005. Similar water saving targets are fixed across the developed world.

INDIA: In India, as of now, there is no law determining the exact amount of water meant for consumption by the various industrial sectors. Though CPCB has prescribed water consumption levels for some industrial sectors, they are mere recommendations and cannot be enforced by laws. India also has some obsolete laws related to groundwater extraction. In Indian law, the person who owns the land also owns the groundwater below. Though this law has some relevance as far as the domestic groundwater use is concerned, it is outright absurd for industrial and commercial use. The result is that today, industries withdraw groundwater that remains unregulated and unpriced.

Regulating pollution
GLOBAL: Regulators are shifting from concentration-based standards to pollution load based standards. The pollution load-based standards determine the total amount of pollutant generated for per unit production. The pollution load-based standards also use the quota system for the amount of water allowed to various industries and therefore, with this standard pollution levels are monitored, as also the amount of freshwater consumed. This forces companies to reduce fresh water consumption as they save on water cost. Also, by introducing 'polluter pays principle' regulators push companies to reduce the total pollution load. Therefore, with the help of pollution load-based standards coupled with the 'polluter pays principle', regulators across the world are reducing fresh water consumption as well as water pollution by industries.

INDIA: In India both these principles are absent. The result is that industries use more freshwater and discharge more pollutants through wastewater and still meet the legal standards. The industrial water pollution standards in the country are concentration based, that is, they measure the concentration of pollution in a given quantity of water. The result is that an industry can meet the required standard merely by diluting the effluent with clean water. Since the cost of water is low, it makes more economic sense for an industry to dilute the effluent than to treat it to meet the standards. l

National Water Policy: Industry is let off!
The issues related to the industrial water have been addressed in vague and fragmented form in National Water Policy (NWP) released in 2002. No clear vision for regulating and controlling industrial water use has been given. The policies stated in NWP, 2002 are just not sufficient to result in modern control and regulation of the industrial water use as an integrated whole.

The entire document of 6000 words mentions industry just 6 times, unmindful of the environmental concerns industrial water use poses.

Water policy says:

Effluents should be treated to levels and standards that are acceptable before discharging them into natural streams.

Comment: Does not address the issue of pollution load. The current standards for industrial effluents are concentration- based, which does not provides incentive for reducing water use or pollution loads.

Principle of 'polluter pays' should be followed in management of polluted water.

Comment: Advocates 'polluter pays' principle' but is silent on extent of payment. Current water cess charged by pollution control boards is a 'polluter pays' regime, but the quantum of payment is so low that there is no incentive or disincentive for the industry for reducing wastewater discharge and hence water use.

Economic development and activities, including agriculture, industry and urban development, should be planned with due regard to the constraints imposed by the configuration of water availability. There should be a water zoning of the country and the economic activities should be guided and regulated in accordance with such zoning.

Comment: Unless addressed in the industrial policy, it has no significance.

Efficiency of utilisation in all the diverse uses of water should be optimised and an awareness of water as a scarce resource should be fostered. Conservation consciousness should be promoted through education, regulation, incentives and disincentives.

Comment: Vague and indifferent.

The resources should be conserved and the availability augmented by maximising retention, eliminating pollution and minimising losses. For this, measures such as selective linings in the conveyance system, modernisation and rehabilitation of existing systems including tanks, recycling and re-use of treated effluents and adoption of traditional techniques like mulching or pitcher irrigation and new techniques like drip and sprinkler may be promoted, wherever feasible.

Comment: Vague and indifferent.

Too many cooks spoil the water management broth
Ministry of water resource (MoWR): It is the principle agency responsible for water in India but water pollution does not fall under its purview, nor does the industrial use of water.

Ministry of Industry (MoI): It is concerned with the planning and development of water resources for industrial use. It has no mandate to control or regulate the water use by industries.

Central Ground Water Board/Authority (CGWB/A): Meant to regulate the groundwater quality and quantity in the country. Though they have mandate to do what they can with groundwater, they have so far only mapped the groundwater status. They have no mandate to charge industrial groundwater use.

Ministry of Power (MoP): Entrusted with development of hydroelectricity, but has no mandate to look after either water consumption or water pollution by the thermal power plants. And this despite the fact that they consume as much as three-fourths of the total industrial water in the country.

Water Quality Assessment Authority (WQAA): Frustrated with the multiplicity of agencies MoEF & MoWR decided to set up this apex body to compile information on water quality and monitor the function of the agencies. But since its constitution, WQAA has only met twice and no progress has been made on its agenda.

Ministry of Environment & Forests (MoEF): It is concerned with the quality of surface and ground water. But it has no mandate to control use of water as raw material. But it has no mandate to handle water scarcity, nor any power to resolve water conflicts.

Central and State Pollution Control Board (CPCB) & (SPCBs): These regulate industrial water pollution and charge water cess based on the amount of wastewater discharged by the companies. But they have no mandate to control sourcing of water from various sources.

Ministry of Rural Development (MoRD): Its responsibilities are: watershed development, the Million Wells Scheme, the Rajiv Gandhi National Drinking Water Mission and developing the source of drinking water in rural areas. But ensuring availability of water and testing for water contamination is not its responsibility.

Ministry of Urban Development (MoUD): It is responsible for drinking water in urban areas but doesn't have the mandate to monitor, regulate or charge water used by industries in urban areas.

Industry can improve the technology to do so exists. But does the will?

Water use in Indian industry is very high due to a combination of factors including obsolete process technology, poor recycling and reuse practices and poor wastewater treatment. Water once used is generally thrown without any further use, even if the water is not much contaminated. Segregation of wastewater from various processes into clean wastewater, (that can be reused) and contaminated water is not commonly done. The result is that even the uncontaminated water gets contaminated after mixing and is discharged as effluent.

Indian industry, especially thermal power plants, consume majority of their water for cooling requirements. Majority of industries use 'once-through cooling systems', in which water once used for cooling is discharged. Similarly, reuse of non-contact steam condensate is also not favoured in India, though it is virtually clean and can be reused by reducing the total dissolved solids (TDS).

The wastewater treatment system in Indian industry is essentially installed to meet the wastewater discharge norms. The design principles do not consider the possibility of recycling and reusing the wastewater. Inevitably, in all industries the wastewater discharged is seldom suitable for reuse within the industry, though industry expects other users to reuse its wastewater because it is 'treated'. Most industries have their water intake points upstream of their wastewater discharge points. This itself exemplifies the quality and interest of wastewater treatment by Indian industry.

Solving the water problem
The key to the problem lies in effective management of water resources. An integrated approach involving water treatment, source reduction, reuse of process water, effluent treatment, recycling of treated effluent and waste-minimisation is urgently required.

Improve process technology: Clean and advanced process technologies can help industry reduce its water demand. For instance, by replacing the conventional bleaching process with totally chlorine bleaching process, pulp and paper companies can almost close their water cycle. But they are costly.

Reuse process water: This involves reusing water in a series, in an open system, for two or more successive but different purposes. This enables use of poor quality water for more than one purpose.

Recirculate process water: Indefinite reuse of same water after treatment for the same purpose. Makeup water is to be used only to replace unavoidable losses. This is far cheaper than installing new process technology and recent technological development has made sure that it can be used by any type of industry.

Rainwater harvesting: This helps industries meet a substantial part of their annual water requirement even as demand on local sources is minimised.

Technology is not the bottleneck
There are enough technologies to solve all water problems and what is more, the prices of these technologies are gradually decreasing. In a nutshell, it quite feasible today for an Indian industry to substantially reduce its water consumption and wastewater discharge by putting efficient systems for recycling and reusing the process water. But for this to happen government policy needs to be overhauled.

CASE STUDY

Cooling water in Indian Thermal Power Plants (TPPs)
According to CPCB's report on Water Quality in India 1990-2001 status and trends of the total wastewater discharged from all major industrial sectors, 80.3 per cent is cooling water generated just from TPPs. Therefore, closing the cooling water cycle should be the priority of Indian industry and the regulators alike.

Two cooling technologies are in use today:
Once-through cooling system: This system requires the intake of a continual flow of cooling water. The water demand for the once-through system is 30 to 50 times that of a closed cycle system. Most Indian TPPs operate this system.

Closed-cycle systems: This system discharges heat through evaporation in cooling towers and recycles water within the power plant. The water required to do this is comparatively small since it is limited to the amount lost through the evaporative process. Because of the expense associated with closed-cycle cooling, once-through systems are far more common. Some recently commissioned Indian TPPs employ this technology.

In once-through cooling system approximately 100 litres of water is required to produce 1 Kwh electricity. In badly managed TPPs this could go up to 200 litres. In comparison in a closed-cycle system, about 2-3 litres water is required to generate 1 Kwh electricity.

By converting all Indian TPPs to closed-cycle cooling system, by rough estimation almost 65,000 mld or 24 billion m3 fresh water can be saved. This is roughly equivalent to India's total domestic water requirement.

In closed-cycle cooling towers water is lost due to evaporation, windage and drift and intentional blow down. These losses are about 1.5-2 per cent of the recirculation rate. Currently fresh water is used as makeup in Indian industry. But with proper treatment of process wastewater and effective chemical treatment to control corrosion and fouling, wastewater can be easily reused in the cooling towers, reducing the freshwater intake for cooling to zero.

In general, combined primary (sedimentation) and secondary (biological oxidation, disinfection) treatment of wastewater is sufficient to make it suitable for cooling towers. Currently most large and medium scale Indian companies are required to treat their wastewater till secondary treatment to meet the pollution norms. Therefore, in these companies no additional investment is required for treating the wastewater and reusing it in cooling towers.

A wide range of chemicals are available today which can reduce the danger of corrosion and scaling in the cooling tower equipment thereby enabling the use of treated effluent as cooling water. Many companies outside India are using treated effluent as cooling water quite successfully. In places where fresh water is quite costly, use of treated effluent as cooling water presents substantial financial gain for the companies.

Membrane Technologies
A semipermeable membrane is a thin layer of material separating substances when a driving force is applied across it. Once considered a viable technology for desalination, membrane processes are increasingly employed for removal of bacteria and other microorganisms, particulate material, organic and inorganic chemicals and colour and other contaminants. As advances are made in membrane production and module design, capital and operating costs continue to decline. The pressure-driven membrane processes are essentially of four different kinds: micro filtration, ultra filtration, nano filtration and reverse osmosis.

Reverse osmosis (RO): RO use for wastewater recycling and reuse process has become quite common. O systems are compact, simple to operate, and require minimal labor, making them suitable for all systems. RO can effectively remove nearly all inorganic contaminants, nearly all contaminant ions and most dissolved non-ions from water. RO is particularly effective when used in series. Water passing through multiple units can achieve near-zero effluent contaminant concentrations.

The pre-treatment section, where the feed is treated by chemical clarification (precipitation, coagulation/flocculation or flotation) and subsequent filtration, or by filtration and subsequent ultra filtration

The membrane section, where high pressure is applied and the waste water is cross-flowed across the membrane

The post-treatment section, where the permeate is prepared for reuse or discharge, and the concentrate brine is collected for further work-up or for disposal

The capital and operating and maintenance cost of RO systems are become quite competitive with the increasing cost of buying water in water-scarce areas. For instance, the cost of treating municipal sewage water by RO in Chennai is in the range of Rs 25-50 per m3 (See: Wastewater treatment...). This is similar (in cases even lower) to the cost of fresh water charged by the Madras Water Supply & Sewage Board.

Industry can improve the technology to do so exists. But does the will?

Water use in Indian industry is very high due to a combination of factors including obsolete process technology, poor recycling and reuse practices and poor wastewater treatment. Water once used is generally thrown without any further use, even if the water is not much contaminated. Segregation of wastewater from various processes into clean wastewater, (that can be reused) and contaminated water is not commonly done. The result is that even the uncontaminated water gets contaminated after mixing and is discharged as effluent.

Indian industry, especially thermal power plants, consume majority of their water for cooling requirements. Majority of industries use 'once-through cooling systems', in which water once used for cooling is discharged. Similarly, reuse of non-contact steam condensate is also not favoured in India, though it is virtually clean and can be reused by reducing the total dissolved solids (TDS).

The wastewater treatment system in Indian industry is essentially installed to meet the wastewater discharge norms. The design principles do not consider the possibility of recycling and reusing the wastewater. Inevitably, in all industries the wastewater discharged is seldom suitable for reuse within the industry, though industry expects other users to reuse its wastewater because it is 'treated'. Most industries have their water intake points upstream of their wastewater discharge points. This itself exemplifies the quality and interest of wastewater treatment by Indian industry.

Solving the water problem
The key to the problem lies in effective management of water resources. An integrated approach involving water treatment, source reduction, reuse of process water, effluent treatment, recycling of treated effluent and waste-minimisation is urgently required.

Improve process technology: Clean and advanced process technologies can help industry reduce its water demand. For instance, by replacing the conventional bleaching process with totally chlorine bleaching process, pulp and paper companies can almost close their water cycle. But they are costly.

Reuse process water: This involves reusing water in a series, in an open system, for two or more successive but different purposes. This enables use of poor quality water for more than one purpose.

Recirculate process water: Indefinite reuse of same water after treatment for the same purpose. Makeup water is to be used only to replace unavoidable losses. This is far cheaper than installing new process technology and recent technological development has made sure that it can be used by any type of industry.

Rainwater harvesting: This helps industries meet a substantial part of their annual water requirement even as demand on local sources is minimised.

Technology is not the bottleneck
There are enough technologies to solve all water problems and what is more, the prices of these technologies are gradually decreasing. In a nutshell, it quite feasible today for an Indian industry to substantially reduce its water consumption and wastewater discharge by putting efficient systems for recycling and reusing the process water. But for this to happen government policy needs to be overhauled.

CASE STUDY

Cooling water in Indian Thermal Power Plants (TPPs)
According to CPCB's report on Water Quality in India 1990-2001 status and trends of the total wastewater discharged from all major industrial sectors, 80.3 per cent is cooling water generated just from TPPs. Therefore, closing the cooling water cycle should be the priority of Indian industry and the regulators alike.

Two cooling technologies are in use today:Once-through cooling system: This system requires the intake of a continual flow of cooling water. The water demand for the once-through system is 30 to 50 times that of a closed cycle system. Most Indian TPPs operate this system.

Closed-cycle systems: This system discharges heat through evaporation in cooling towers and recycles water within the power plant. The water required to do this is comparatively small since it is limited to the amount lost through the evaporative process. Because of the expense associated with closed-cycle cooling, once-through systems are far more common. Some recently commissioned Indian TPPs employ this technology.

In once-through cooling system approximately 100 litres of water is required to produce 1 Kwh electricity. In badly managed TPPs this could go up to 200 litres. In comparison in a closed-cycle system, about 2-3 litres water is required to generate 1 Kwh electricity.

By converting all Indian TPPs to closed-cycle cooling system, by rough estimation almost 65,000 mld or 24 billion m3 fresh water can be saved. This is roughly equivalent to India's total domestic water requirement.

In closed-cycle cooling towers water is lost due to evaporation, windage and drift and intentional blow down. These losses are about 1.5-2 per cent of the recirculation rate. Currently fresh water is used as makeup in Indian industry. But with proper treatment of process wastewater and effective chemical treatment to control corrosion and fouling, wastewater can be easily reused in the cooling towers, reducing the freshwater intake for cooling to zero.

In general, combined primary (sedimentation) and secondary (biological oxidation, disinfection) treatment of wastewater is sufficient to make it suitable for cooling towers. Currently most large and medium scale Indian companies are required to treat their wastewater till secondary treatment to meet the pollution norms. Therefore, in these companies no additional investment is required for treating the wastewater and reusing it in cooling towers.

A wide range of chemicals are available today which can reduce the danger of corrosion and scaling in the cooling tower equipment thereby enabling the use of treated effluent as cooling water. Many companies outside India are using treated effluent as cooling water quite successfully. In places where fresh water is quite costly, use of treated effluent as cooling water presents substantial financial gain for the companies.

Membrane Technologies
A semipermeable membrane is a thin layer of material separating substances when a driving force is applied across it. Once considered a viable technology for desalination, membrane processes are increasingly employed for removal of bacteria and other microorganisms, particulate material, organic and inorganic chemicals and colour and other contaminants. As advances are made in membrane production and module design, capital and operating costs continue to decline. The pressure-driven membrane processes are essentially of four different kinds: micro filtration, ultra filtration, nano filtration and reverse osmosis.

Reverse osmosis (RO): RO use for wastewater recycling and reuse process has become quite common. O systems are compact, simple to operate, and require minimal labor, making them suitable for all systems. RO can effectively remove nearly all inorganic contaminants, nearly all contaminant ions and most dissolved non-ions from water. RO is particularly effective when used in series. Water passing through multiple units can achieve near-zero effluent contaminant concentrations.

The pre-treatment section, where the feed is treated by chemical clarification (precipitation, coagulation/flocculation or flotation) and subsequent filtration, or by filtration and subsequent ultra filtration

The membrane section, where high pressure is applied and the waste water is cross-flowed across the membrane

The post-treatment section, where the permeate is prepared for reuse or discharge, and the concentrate brine is collected for further work-up or for disposal

The capital and operating and maintenance cost of RO systems are become quite competitive with the increasing cost of buying water in water-scarce areas. For instance, the cost of treating municipal sewage water by RO in Chennai is in the range of Rs 25-50 per m3 (See: Wastewater treatment...). This is similar (in cases even lower) to the cost of fresh water charged by the Madras Water Supply & Sewage Board.
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Source: Down To Earth Magazine