Part rubbish heap, part sewage works, the wetlands of Kolkata are among the world's great eco-systems, says Tony Juniper
The overpowering stench of human waste hangs heavily on the humid air. In the 37C heat preceding the imminent monsoon, it is almost suffocating. But the smell is not surprising when you know that the wetlands to the east of Kolkata, or Calcutta as the teeming metropolis used to be known, receive some 680m litres of raw sewage every day. Amazingly, the wetlands' mosaic of ponds, lakes, channels and swamps are the only sewage treatment facilities the 12 million or so inhabitants of the city have.
And that's not all: the wetlands are also the destination for more than 3,000 tonnes of municipal waste produced in Kolkata each day. Despite being a sink for the less pleasant products of a vast city, the wetlands are also important for conservation. An impressive range of migrant and -resident birds and animals can be spotted there, including the endemic marsh mongoose.
Perhaps surprisingly, given they are in part rubbish dump and sewage works, the east Kolkata wetlands are listed under wetlands of international importance by the Ramsar Convention. This is not solely because of their wildlife value; primarily it is because the ecosystem supports diverse human activities, and therefore - theoretically - could advance the convention's objective of promoting sustainable use of wetlands - as well as their protection.
Use of the wetlands is intense. The roads that bring visitors from Kolkata pass through the areas where the city's waste is dumped. It is sorted by bands of so-called rag pickers. People existing on the margins of society process the waste into neat piles of translucent polythene, sparkly piles of aluminium foil fragments, mounds of glass, scrap metals and, the real prize, compost.
The work is filthy and dangerous. Broken glass and clinical waste are mixed in with the unsorted waste. The pickers, including young children, have no protective clothing, not even gloves. Under these dreadful conditions, the pickers manage to scratch a living. Sorted materials are sold for recycling, while the compost is spread on plots of land that produce a variety of vegetables.
Adjacent to the little vegetable plots, sewage arrives from the city along slow flowing channels. As the solids separate out, the ponds are dredged and the black solids spread on to the small fields and garden plots that intersperse the wet areas. This material, along with the compost and irrigation from the waste water, helps the people who live and work on the wetlands to produce tonnes of vegetables.
Once solids are dredged out, the liquid fraction is passed to pools filled with fast-growing water hyacinths. These tough but rather at tractive plants not only accumulate biomass but absorb some of the heavy metals and other toxins released from small-scale industries, such as tanneries.
When the organic pollution in the water is partly diminished by the plants, it is used to top up fish ponds. All across the wetlands there is fish rearing - and on a grand scale. About a dozen species of freshwater fish are raised, in more than 300 ponds covering about 35 square kilometres. Between them, they produce a staggering 13,000 tonnes of fish a year, much of it consumed in Kolkata.
Some 50,000 people depend on the wetlands for their living: growing vegetables, trading and making nets, or maintaining the channels. The fish rearing alone supports a workforce of about 8,000 people. Many also rear pigs and ducks. The pigs run semi-wild and eat whatever they can find. The ducks are fattened with aquatic snails harvested from the ponds.
Sustaining this unique system should be a priority for policy makers, and researchers, including a group from the University of Stirling in Scotland, are embarked on that process. If the lives of the people and the economy of this place can be better understood, then perhaps their welfare can be improved, alongside moves toward long-term sustainable management. The alternative is the development of the wetlands for ur ban expansion, that would, in turn, lead to a loss of food for the city and necessitate the construction of expensive sewage works.
There are problems. The expansion of Kolkata and the ever present pressure of development is thought by some to be the reason why no official boundary map of the Ramsar-listed area has been published. The government of West Bengal, it is thought, is hedging its bets on where development will go before committing to a legally binding boundary.
Siltation is a growing problem as well, with many of the fish ponds gradually filling up. If the wetlands are to survive, then large-scale dredging will be needed. And as the city grows ever larger, so the volume of sewage and waste grows, too. How long the wetlands can accommodate that growth is not known.
One of the few new commitments made by governments at the 2002 Johannesburg summit on sustainable development was to improve access to sanitation. However, if there is really a context of sustainable development in which that aim will be pursued then not only should there be an emphasis on concrete, pipes and electricity but also an appreciation of the central role that can be played by people, habitats and farming.
3. What a waste: we could be recycling more
Consumers are sending more rubbish to landfill sites than necessary because they are unclear about which things can be recycled and which cannot, a survey indicated today.
In research for the vocational qualifications provider City & Guilds, 88% of UK households said they were already recycling some of their waste. But nearly half (46%) thought they could improve if they better understood which materials could be recycled.
Even those who did try to recycle as much as possible often got it wrong, according to council staff.
More than half told researchers householders tried to recycle the wrong types of plastic, with 58% saying that such mistakes slowed up the recycling process.
Figures from the Office of National Statistics have suggested that Britons throw away an average of their body weight in rubbish every seven weeks, an amount City & Guilds said could be reduced if the process were less complicated.
The organisation is launching a new NVQ qualification for recycling staff, which it says will help them with customer care and safety and inform them of changes in one of Britain's fastest growing sectors.
John Birch, waste recycling expert at City & Guilds, said: "Our research shows that householders are more knowledgeable about recycling and would like to do much more.
"With the average dustbin containing enough unrealised energy for 3,500 showers, better recycling will certainly make a huge impact on our resources and environment."
Philip Ward, director at Waste and Resources Action Programme (Wrap) welcomed the new qualification.
"More and more of us are getting into the recycling habit, but sometimes we have questions about how and what can be recycled," he said.
"This will help council frontline staff answer those questions, making the service as easy and straightforward as possible."
Wrap, which was set up by the government in 2000, is currently working to reduce the amount of waste that goes to landfill sites by 3m tonnes and recruit at least 4 million members of the public to become "committed recyclers" by March 2008.
It claims more than 50% of household waste could be recycled - more than double the amount recorded in the last set of government figures.
These show that in 2004-5, households in England recycled almost 23% of their rubbish, compared with 57% in Germany, 64% in Netherlands and 41% in Denmark.
Local councils, which are under pressure from the government to reduce landfill and hit recycling targets, are becoming increasingly strict with householders.
Section 46 of the Environmental Protection Act 1990 gives councils the power to specify what kinds of waste should be placed in which bins, and homeowners can face fines of up to £1,000 if they get it wrong.
Compulsory recycling schemes have been launched in some parts of London, and earlier this year Exeter council took a resident to court after rotting food was found in the wrong bin.
It lost its case because it was unable to prove that the rubbish had not been dumped by a passerby.
Today Kennet District Council in Devizes said it would issue penalty notices to residents who put out black sacks of rubbish alongside their wheelie bins, using powers granted in the Clean Neighbourhood and Environment Act.
The council leader, Chris Humphries, said the government fined local authorities like Kennet for exceeding rubbish targets and that cost would inevitably be passed on to the taxpayer.