Here, wastewater is food for fish, fertiliser for crops

What do you do with 15,000 million litres of wastewater dumped into rivers by towns and cities every day? If you’re in the Government, you set up a committee; if you’re an environmentalist, you cry foul; if you’re a cynical citizen, you call it a lot of plain muck.

But the Rahara farm near Barrackpore in West Bengal has embarked on a mission, which, if adopted throughout the country, could prove revolutionary in treating polluted water. Set up by the Central Institute of Freshwater Aquaculture, it looks rather like any other green, picturesque farm. Rahara, however, breeds fish in and grows vegetables with untreated wastewater.

What’s more, the costs at Rahara are a fraction of what commercial farming requires. The products are as safe and tasty as any conventionally irrigated farm.

Wastewater is actually rich in nutrients and highly favourable for phytoplankton (fish food). Water hyacinths are employed to bring down toxicity levels of the water.

The farm has successfully bred Bengali staples such as Rohu, Catla, Bata and even freshwater prawns in wastewater. The fish also rids the water of its polluting elements and renders it safe for release into rivers.

Scientists also that wastewater can be used to grow foodgrain, flowers as well as breed fish. Sewage water proves to be an alterative fertilizer for paddy. Medicinal crops like turmeric, ginger and garlic can also be produced.

It is a symbiotic system where the byproducts of growing vegetables can be again used for growing vegetables can be again used for production of fishes.
“In fact,” says Dr Maniranjan Sinha, Director of the Central Inland Fisheries Research Institute in Barrackpore, “water pollution is the least of our problems.”

However what does worry them is that the water level of most Indian rivers is going down. This has severely affected the supply of fish needed from rivers from time to time to avoid the consequence of chronic inbreeding. “At this rate, there will be no rivers in 20 years,” says Dr Sinha.

The institute is also working on air breathing fish that do not need freshwater to survive, such as Singhi, Magur, Koi and Murrels. They keep coming up to the surface to breathe and can survive in sewage water.

Surprisingly, they also have great nutritional value and are recommended by doctor for people recovering from illness.

Dr Sinha points out that such varieties of fish would be ideal for breeding in polluted rivers like Delhi’s own Yamuna, where there is hardly any freshwater left.

The river Ganga has become cleaner, though the decrease in the water level has resulted in the decrease in the number of fish in the river, says Dr Sinha.

CIFA claims that fish culture through sewage water is in practice in Russia, a number of Asian countries and many parts of Europe.

(This article appeared in the Hindustan Times newspaper on May 14, 2000)