Even as several countries lack data on reuse of wastewater, Metro Water officials claim that Chennai is the pioneer in utilising treated wastewater for industrial use.
A study by Japan’s Tottori University and the United Nations University’s Canadian-based Institute for Water, Environment and Health (UNU-INWEH) claims that almost one-third of nations have zero information on the reuse of waste water. However, Chennai’s Metro Water officials say that they are currently providing 45 Million Litres per Day (MLD) of treated water to industries.
“We are also planning to generate 60 MLD of additional treated water to be supplied to Sriperumbudur Industrial Estate, which is a hub of industrial activities, in the outskirts of the city,” says a Metro Water official.
He adds that a detailed report for the project is likely to be completed within two months. But, experts want Metro Water to do more. S Janakarajan, professor of Madras Institute of Development Studies (MIDS), feels that recycling is important for conservation of water. He says water management is complete only when we reuse water.
“Metro Water is using very little reused water. It is hardly five per cent of it, despite so many treatment plants being set up,” says Janakarajan, whose institute has undertaken a project on ‘Sustaining the ecology of Chennai and its peri-urban Areas: A Long term Strategy Document for Water Conservation’ funded by the Department of Science and Technology, Government of India.
Even the policymakers abroad are looking at treated wastewater for farming and other purposes. An international study predicts a rapid increase in the use of treated wastewater for farming and other purposes worldwide. This, according to the study, is in the wake of growing competition for fresh water from industry and cities, coupled with a rising world shortage of potash, nitrogen and phosphorus.
But the biggest issue is lack of awareness about treated wastewater in Indian cities, says Janakarajan. He says many cities in India are not treating their wastewater. However, lack of awareness about treated wastewater is a global phenomenon. The international study states that of the 181 countries studied, only 55 have information on three key aspects of wastewater: generation, treatment, and reuse. Another 69 countries have data on one or two aspects, 57 countries show no information on any aspect.
Water demands already exceed supplies in regions with more than 40 per cent of the world’s population and in just 12 years, as much as 60 per cent of the world’s people may face water scarcity.
Synthesising data on wastewater treatment, the study shows that on an average, high-income countries treat 70 per cent of the generated wastewater, upper-middle-income countries treat 38 per cent and lower-middle-income countries treat 28 per cent. Just eight per cent of wastewater generated in low-income countries undergoes any kind of treatment. Only about 32 per cent of the wastewater generated in Asia is treated.
It is claimed that wastewater is used for 1.5 per cent to 6.6 per cent of the global irrigated area of 301 million hectare area (1.2 million square miles) and that about 10 per cent of world food is produced using wastewater. However, according to the study, there is little data to support such claims.
In developing countries, particularly in water scarce countries, wastewater volumes are thought to have increased substantially in recent years due to rural-urban migration. Many farmers in water scarce developing countries irrigate with wastewater because it is the only water source available for irrigation year-round and wastewater irrigation reduces the need for purchasing fertiliser, the study states.
The combination of less freshwater allocation to agriculture and growing volumes of urban wastewater, is expected to continue and intensify, particularly in water scarce countries.
Agriculture in these countries will increasingly rely on alternative water resources, such as wastewater generated by non-agricultural activities in urban and peri-urban areas.
Under-reporting of wastewater generation, treatment and reuse might relate to fear of economic repercussions in agricultural trade due to concerns regarding food safety and phyto-sanitary measures, the report states.