Sewage Farm – Cambodia

Cambodia’s capital, Phnom Penh, sits by the Mekong River, which provides both transport and income for the city’s one million population. A nearby stretch of water, the Beung Cheung Ek Lake, which receives most of the city's sewage, is offering economic opportunities for three and a half thousand families living around its shore. They earn a living by cultivating aquatic vegetables, in particular Morning Glory, which is a popular food in all the Asian cities on the Mekong.

The people living in stilted houses on the lake are mostly informal settlers who fled the city in the 1970s during the brutal reign of Pol Pot. As the city expands there is increasing pressure on land and water resources. This nutrient-rich crop, grown using the city’s sewage system, is one way of feeding cities on existing resources while helping the urban poor – providing them with food, employment and income.

Family homes are built on stilts over the areas of Morning Glory cultivation.

PAPUSSA
Phnom Penh is one of four Asian cities being studied by a project called PAPUSSA (Periurban Aquatic Production Systems in South-east Asia), supported by the European Commission and the UK Department for International Development, DFID. The objective of the project is to understand more fully the aquatic production systems around major cities in South-east Asia. The research is looking at production, livelihoods, markets and institutional features that affect the wide range of stakeholders involved in this economic activity.

The use of aquaculture ponds enriched with human wastes has been an effective way of growing plants and rearing fish in Asia for thousands of years. The Beung Cheung Ek Lake acts as a wetland area to control flood waters and to remove pollutants from Phnom Penh city before the water flows into the Mekong River.

Harvesting Morning Glory

The sewage outflow, which takes up to 80 per cent of the sewage from the city, is not yet separated, so the floodwaters and sewage waters mix together. The drainage sluiceway pumps both waters out of the city into the lake, and this enriched water provides a perfect environment for the cultivation of Morning Glory.

The scale of Phnom Penh’s Morning Glory production can be estimated using satellite imagery at the Inland Fisheries Research and Development Institute. The area being cultivated is approximately 200 hectares.

Morning Glory Cultivation
Morning Glory is first grown on land, where cuttings are taken and propagated as new stock. After one or two months, once these seedlings have grown large enough, they are replanted in the lake. This area is enclosed within a network of ropes connected to poles to prevent the Morning Glory from drifting away and also to demarcate the plot. The plants thrive in the nutrient-rich waters, although fertilisers and pesticides are also used.

The plants are soon ready for harvesting – there are three harvesting periods throughout the year. In the dry season the quality of the crop is poorer, so then it is often used as a fodder for pigs. Yields can be high, even from relatively small areas. Farmers often employ casual labour to harvest the crop, and further employment is involved in transporting the crop to the local markets, where these fresh, versatile greens are very popular.

Harvesting and transporting Morning Glory to market.

Health Risks
Surveys conducted by the PAPUSSA project show average household income from Morning Glory production is 10 to 20 dollars (£6-£12) a day during the harvesting period (although seasonal factors can affect these earnings). This is a valuable income for poor families, and they persist with cultivation despite some health risks. They are prone to skin diseases, such as dermatitis (eczema) and parasitic scabies infection. They can suffer from stomach complaints and diarrhoea. Some initial research suggests that the use of protective clothing may reduce the risk of skin problems. Farmers are increasingly using long rubber gloves and boots now that softer materials are available that are cheaper and easier to use.

There are also concerns over the safety of eating Morning Glory – cooking it destroys most harmful bacteria, but some people eat it raw. In this case it is recommended that it is washed in a solution of potassium permanganate but in the rural areas this may not be available, in which case it should be washed thoroughly, with repeated rinses.

Future Prospects
Cultivation is officially encouraged since it has the added benefit of taking up excess nutrients in the lake. In 2000, the government announced fisheries reforms that released this area for public access and it is beginning to work more closely with aquatic resource managers. In fact, aquatic plant production is mutually beneficial. The plants reduce harmful substances such as phosphorus and nitrogen, and take up bacteria and other pathogens from the wastewater. They also reduce the risk of eutrophication, which would destroy aquatic life by excluding oxygen from the water.

However, there are concerns that growing urbanisation is encroaching on this land. There are pressures to build housing and the increasing amount of sewage could have a detrimental affect on the water quality. There are also fears about poorly controlled toxic and hazardous wastes from nearby industries that are increasing chemical pollution.

Little information has been collected on the extent of this production – even the Food and Agriculture Organisation (FAO) does not have statistics on its cultivation. This means there is little evidence to support the importance of this crop, and to ensure measures are put in place to protect its future.

The PAPUSSA research project aims to gain a wider understanding of the production systems to see how this activity can be supported. There could be opportunities for the cultivation of Morning Glory to be expanded into other Asian cities. Measures could be taken to treat or process Morning Glory after harvesting to make it safer to eat. As is already occurring with terrestrial vegetables in Thailand, organic production could be developed to meet a more specialised market. More information will be gathered in the remaining years of the PAPUSSA project to evaluate the potential of this market.

Acknowledgement
Hands On would like to thank DFID’s Aquaculture and Fish Genetics Research Programme, although the views expressed are not necessarily those of DFID.

Further Information

Contacts
Albert Salamanca – University of Durham, UK
E-mail: albert@ait.ac.th

William Leschen – Institute of Aquaculture, University of Stirling, UK
E-mail: wl2@stir.ac.uk

Participating Organisations
Institute of Aquaculture
University of Stirling
Scotland FK9 4LA
UK
Tel: +44 (0)1786 467900
Fax: +44 (0)1786 451462
E-mail: afgrp@stir.ac.uk
Website: http://www.dfid.stir.ac.uk/Afgrp/

PAPUSSA (Periurban Aquatic Production Systems in South-east Asia)
PAPUSSA is a collaborative research project between European and Asian partners seeking to better understand the importance and nature of aquatic food production that occurs in and around some of the major cities of South-east Asia.
Website: http://www.papussa.org

Royal University of Agriculture
Donkor District, P.O. Box 2696
Phnom Penh
Cambodia
Tel: +855 23 219 829,
Fax: +855 23 219 753 690
E-mail: rua@forum.org.kh
Website: http://www.rua.edu.kh

Inland Fisheries Research and Development Institute (IFReDI)
Department of Fisheries
186, Norodom Blvd, P.O. Box 582
Phnom Penh
Cambodia
Fax: +855-23-220417

References
Urban Aquatic Production. Urban Agriculture Magazine, No 14, Jul 2005 http://www.ruaf.org/node/529

Minutes of the Workshop on Peri-urban aquatic production and improvement of the livelihoods of the urban poor in South-East Asia. 22-23 Nov 2005, Dhaka, Bangladesh. Bangladesh Fisheries Research Forum (BFRF) and Practical Action Bangladesh.
http://www.papussa.org/publications/
dhaka_workshop_minutes.pdf

TVE/ Practical Action gratefully acknowledge support for the HANDS ON programmes from the UK's Department for International Development (DFID), the European Commission (EC), the UN Foundation and UNDP/The Equator Initiative in collaboration with the Government of Canada, IDRC, IUCN, BrasilConnects and the Nature Conservancy.