Smart, eco-friendly sanitation for all

by S Viswanath

The technology choice that China made for sanitation and wastewater management has led to not only blistering economic growth but also rapid urbanisation as it helped Beijing reduce GDP loss that poor sanitation brings

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. Greywater 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.
China, and rural China in particular, has been well-known for centuries for reusing human waste as a fertiliser.

Legendary tales are told of farmers competing with each other in inviting passersby to use toilets in their fields so that they could access the fertiliser. There was never any waste only a resource according to the Chinese farmers. This was, however, a small part of the story.

Rural sanitation has been a problem for long. In 1996, only about 20 per cent of households had access to sanitation. The prevalence of open defecation, the use of the traditional pit latrines and in general bad sanitation practices, including the application of untreated human waste for

agriculture, had led to the high prevalence of intestinal diseases such as worms in the rural population. A focussed attention first on rural drinking water supply improvement then followed by sanitation access improvement has resulted in about 50 per cent of the populace having access to safe sanitation by 2003.
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.

Take the case of the urine diverting dry toilets. The UDDT’S have a pan designed that collects urine and faeces separately. In the case of washers the wash water is also collected separately. The first experiment in Guangxi Province started with the construction of 70 toilets in Dalu village in 1997. This was followed by the construction of 10,000 UDDT’s in 1998 and then scaled up to the construction of 6,85,000 toilets in 2003. The construction of the UDDT’s has thus been mainstreamed as one of the sanitation alternative while providing the nutrients that farmers need for their fields in a safe and hygienic manner.

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, to improve and implement such a system.
The methane digester type of toilet, much like our biogas systems, has an innovative component to it. Typically, the toilet of the house is also connected to pig rearing, a poly-house and vegetable cultivation. The Chinese call it the four in one model.

Pig effluent and human effluent go into the methane digester that produces biogas for cooking and for electricity for the house usually not connected to the grid. The digested effluent is used as a fertiliser inside the poly-house used for vegetable cultivation by the rural family. More than a million such units have been established and are running all across China.

Till the 1970s, China meandered along with a set pattern of slow growth till Deng Xiaoping unleashed the economy. The result, decades later, is not only a blistering economic growth but also rapid urbanisation. More than 46.60 per cent of China lived in urban areas in 2009 and the tipping point of 50 per cent is expected to be reached by 2015. More than 300 million Chinese will move in to cities between 2010 and 2025. This will put a tremendous strain on water supplies and waste treatment required to manage the sewage flows adequately.

Chinese rivers are under tremendous stress and are hugely polluted mostly through untreated or undertreated wastewater flows which reach the rivers. A massive commitment has, therefore, been made by the state to provide wastewater treatment plants in all cities by the end of 2010, though recent reports suggest that the target is unlikely to be achieved this year.

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 $1.17 billion on

wastewater treatment facilities and $2.25 billion in just the first half of 2010.
The system of wastewater treatment and reuse is best exemplified by what Beijing does. The city has a population of 22 million. In 2009 it consumed a total of 3.55 billion cubic metres of water though many experts suggest that a sustainable water use is around 2.1 billion cubic metres. Most of the additional water came from the sinking of bore-wells and the exploitation of groundwater which is rapidly sinking.

Almost 93 per cent of Beijing's wastewater is collected and treated in 9 treatment plants. The Beijing authorities expect a 100 per cent collection and also a 100 per cent reuse by the end of 2011, thus supplementing Beijing's non-potable water use requirement. By recycling wastewater and by increasing the tariff of water to control its use Beijing authorities hope to see some sustainability in the city's water needs.

While there are many small sewage treatment plants, the Bailonggang wastewater treatment plant in Shanghai is the world's biggest and treats 3.4 million cubic metres daily. The cause for worry in China is that 61 cities have no sewage treatment plants which are around nine per cent of urban areas.

The lessons for India from a neighbour equally large and with a population which is also large are clear. Invest in sanitation and wastewater, make available treated wastewater for reuse in urban areas and reduce the GDP loss due to bad health and disease which bad sanitation brings.

(The writer works on sustainable water management and sanitation issues.)