An enterprising group of fishermen in Calcutta, India, have found a way to 'farm' the city's waste!

Max with Mundially Fishermen's Co-operative Members, Calcutta

The 150-member co-operative utilises the effluent from the city, using natural systems to clean the water and farm fish. The total park area used is 80 ha, of which 60 ha is under water. Fishing takes place every day providing each member with a monthly income of $US50-60.

No chemicals are used and the members have a high respect for natural processes; for example lime is not used - instead Calliandra planted close to the water's edge has been found useful in moderating pH.

About 35 million litres of sewerage a day finds its way via 425m of canals to this amazing site. The wastewater (70% industrial and 30% domestic sewerage) is pre-treated by water hyacinth and reeds before it flows into a pond 125ft (38m) deep. Here much of the sludge containing heavy metals settles and oxygen content is often zero.

The second pond is 100ft (30m) deep and improvements are clearly visible in the water quality. The 3rd pond, 75 ft (25m) deep, always contains frogs (which at times move into pond two) which are seen as natural water quality indicators. Ponds 4 and 5 are planted with reeds and water hyacinth as well as lemna. From here water of satisfactory quality is directed into 9 ponds. These are stocked with fish (Tilapia, various carp, catfish) which grow up to 2.5kg each.

Max Lindegger