Invest in sanitation and wastewater, make treated wastewater available for reuse in urban areas and reduce the GDP loss due to bad health and disease which bad sanitation brings. These are the lessons that India can learn from neighbouring China, says S. Vishwanath, a writer on sustainable water management and sanitation issues.
The four storied apartments in Dongsheng District of Erdos Municipality in Inner Mongolia, China look like any apartment, all 825 of them. They look the same that is until you use the toilet. Detailed instructions nailed to the door tell you how to use them. The urine diverting toilets flush with sawdust instead of water. Urine is collected in tanks tucked away in the basement of the building and used as a fertiliser in a surrounding agricultural field. The solids are composted and reused also as fertiliser. Grey-water coming from the washing machine and bath is treated at a small treatment plant in the development and reused for landscape use. The people who bought the flats did so knowing fully well the systems of sanitation in place and paid the same market rates as the flats which had conventional sanitation systems. This is China’s brave new world of waste and wastewater management.
Rural China has been reusing human waste as a fertiliser for centuries. The downside until recently, was that the application of untreated human waste for agriculture led to the high prevalence of intestinal diseases. Between 1996 and 2003, access to safe rural sanitation increased from 20% to 50%.
The technology choice made for sanitation was also interesting. These included five major types of sanitation systems — the triple compartment septic tank type, the double barrel urn type, the methane generation digester type, the eco-san separate urine faeces collector type and finally the conventional sewer type.
While the first and the last are designed exclusively for isolating and treating sewage to safe standards only, the remaining three systems are designed not only for safe treatment but for reuse of nutrients as well as for generation of energy in the case of the methane digester type.
In Guangxi Province 685,000 urine diverting dry toilets (UDDTs) were constructed between 1997 and 2003.
The factors for such a rapid and large up-scaling has been the cultural acceptance of the technology, the water scarcity in the villages also makes the UDDT attractive as it needs no water for flushing, the availability of compost and urine as fertilisers, the technological and political commitment to improve and implement such a system.
In China there are over a million methane digester type of toilets, which are connected to pig rearing, a poly-house (plastic greenhouse) and vegetable cultivation. Called the four in one model, pig effluent and human effluent go into the methane digester that produces biogas for cooking and electricity. The digested effluent serves as fertiliser to grow vegetables in the poly-house.
Urbanisation is putting a tremendous strain on water supplies and wastewater treatment. The target to provide wastewater treatment plants in all cities by the end of 2010 has not been achieved. Some 61 cities, nine per cent of urban areas, still lack sewage treatment plants
China has currently 4,254 sewage treatment plants with a treatment capacity of 226 million cubic metres. Another 1,849 sewage treatment plants with a treatment capacity 46.6 million cubic metres are under construction. In 2009 China spent US$ 1.17 billion on wastewater treatment facilities and US$ 2.25 billion in just the first half of 2010.
In Beijing almost 93 percent of wastewater is collected and treated in 9 treatment plants. By the end of 2011, the city expects a 100 per cent collection and also a 100 per cent reuse to supplement its non-potable water use requirement.
Source: S. Vishwanath, Morung Express, Jan 2010