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On embedding urban food production and linking it to productive sanitation for the city

March 2, 2013

Summary: Urban India is a repository of many crises. From housing shortage, congestion, water shortage, waste-water prevalence, transport problems, energy and food/ nutrition shortage. While in the long run better urbanization and land-use policies will have to be done in the short run there are some ameliorative steps that can be taken.

It is possible to link water, productive sanitation, waste management and agriculture in a cyclical consumption pattern where the output becomes an input for the other sector. It is possible to find solutions at the household level and also at the city level with intermediate steps also part of the scale of solution.  One such example is presented in the paper below.

Introduction: Urbanization is a phenomenon which India like many other developing nations is experiencing. Though progressing at a slow pace the country is slowly but surely urbanizing with the percentage of population in urban areas as a ratio to rural population on the increase.

The Census of India 2011 identifies the presence of more than 7000 census towns, areas showing urban characters either in terms of density of population, employment in non-agricultural sectors or in terms of definition as urban areas.

Urban India as it expands converts its peripheral land from agricultural and ecological uses to urban uses. Often fertile lands are converted to industrial or housing use. The urban value of land being of higher economic value agriculture is a big loser.

On the other hand the fast growing cities need more and more food grains and vegetables to feed the ever increasing population. Vast streams of water are now to be transported over great distance to slake the thirst of the city. Groundwater from the city is pumped up from great depths to supplement piped water. Both the surface and groundwater so consumed now is let out as waste-water. This waste-water full of nutrients and pollutants flows in our sewage lines – if they exist – or in storm water drains and null

The Census of India 2011 revealed some startling data on the sanitation situation in India. Of the total households numbering 246,692,667 a staggering   53.10 % had no toilets. While a large percentage was rural, urban areas too reported open defecation.

Urban sanitation:  In urban areas underground water borne sewerage systems are slowly making progress but if all the towns in India  are to be fully  covered it will take large investments and a long time not to mention large volumes of water needed for flushing. In the meantime people are building septic tanks and pit toilets for themselves which will need to be emptied and the septage managed in a hygienic way and if necessary the nutrients recovered to aid the soil in the peri-urban areas in becoming productive.

Enter the ‘Honey-sucker’, a truck or tractor based pump, store and transport system developed in the formal but mainly in the informal sector. These pit emptying trucks are rapidly expanding and providing service especially in the Southern and Western states. In the city of Bangalore for example there may be 200 to 300 such trucks providing assistance to over 150,000 households for pit emptying.

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Honey-suckers – Pit and septic tank emptying trucks equipped with de-sludging pumps

When pit toilets or septic tanks are full, at the call of a mobile number these honey-suckers will arrive and do a pit emptying job in 15 to 20 minutes without any human contact with the waste. They charge a small fee of Rs 1200 to Rs 1500.  They then take the sludge to farms in some cases where farmers after composting the sludge in turn sell it for Rs 2000 a tractor load. The whole enterprise is financially sustainable and has no subsidy component anywhere.

Rural Sanitation: While eco-sanitation systems (which is usually Urine diverting toilets collecting urine and faeces separately to be managed) are slowly increasing in numbers they form a minuscule portion of the total toilets being constructed.

The overwhelming numbers of toilets in the 10’s of millions are single pit or double pit toilets. These pit toilets, connected to our flush latrines, are filling up fast and will need to be emptied. With the Manual Scavenging Act being rigorously enforced the only way to do it legally will be through a process of mechanization which means a smaller version of the Honeysucker.

Smaller Honeysuckers for rural areas are a possibility

Honeysuckers emptying into and Sludge composting beds set up by a farmer

  

Composted sludge used as a fertiliser to grow bananas – replaces costly artificial fertiliser

 

The Bangalore method of composting faecal sludge: This method of composting was developed at Bangalore in India by Acharya (1939). The method is basically recommended when night soil and refuse are used for preparing the compost. The method overcomes many of the disadvantages of the Indore method such as problem of heap protection from adverse weather, nutrient losses due to high winds / strong sun rays, frequent turning requirements, fly nuisance etc. but the time involved in production of finished compost is much longer. The method is suitable for areas with scanty rainfall.

Preparation of the pit Trenches or pits about one metre deep are dug; the breadth and length of the trenches can be made depending on the availability of land and the type of material to be composted. The selection of site for the pits is made as in the Indore method. The trenches should preferably have sloping walls and a floor of 90-cm slope to prevent water logging.

Filling the pit: Organic residues and night soil are put in alternate layers and, after filling, the pit is covered with a 15-20 cm thick layer of refuse. The materials are allowed to remain in the pit without turning and watering for three months. During this period, the material settles down due to reduction in volume of the biomass and additional night soil and refuse are placed on top in alternate layers and plastered or covered with mud or earth to prevent loss of moisture and breeding of flies. After the initial aerobic composting which is for about eight to ten days, the material undergoes anaerobic decomposition at a very slow rate and it takes about six to eight months to obtain the finished product.

 

Vijayapura:  It is a small town about 60 kilometers from Bangalore surrounded by rich agricultural land. As water shortages increase and as groundwater tables fall all around our cities and towns interesting behavior patterns emerge and consolidate around waste-water. Imagine a farmer cultivating his 5 acres of land. His bore-well which has gone 1000 feet deep now runs dry because there is no rain and therefore no recharge of groundwater. He sees the city’s sewage water flowing nearby. What should he do? Overcoming his own apprehension he starts to use it on his field. He realizes that the water has nutrients too but they need careful handling since they may burn his crop or destroy his soil. He learns quickly and develops a palate of plants that can tolerate the waste-water and still be productive. He has also to manage the waste-water that the farm labourers do not run away.  He carefully now husbands this resource and makes productive use of it. He grows fodder, he grows maize and he finds a market demand for it. Is he doing the right job?

Conclusion: Embedding food production as part of the vast waste-water movement cycle of cities is happening at an informal level. These systems need to be better understood and tweaked to remove negative externalities and public health issues if any.

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