Natural Wetlands Wastewater Treatment, Phnom Penh
Sustainable Sanitation and Impact of Sewer Discharges on Receiving Water in Phnom Penh, Cambodia
New construction both within the main city of Phnom Penh and in the outer suburban areas and new satellite cities (International City, CamKo City) continues to change the look of this area. The current population of Phnom Penh is 1.4 million and it is anticipated that by 2020 the population of the city will be about 2 million. Phnom Penh is serviced by a combined sewer system consisting of underground concrete and PVC pipes that discharge to several main open interceptor sewers. Most residences have septic holding tanks prior to discharge to the sewer system, but there is no industrial pre-treatment program in place. The interceptor sewers subsequently discharge to the natural treatment wetlands that ring the city.
The International Foundation for Science (IFS) and Swedish International Development cooperation Agency (SIDA) recently funded a team project, The Role of Phnom Penh’s Wetlands in Sustainably Treating Sewage Discharges to the Mekong/Bassac River System. The overarching objective of this project was to determine the effectiveness of Phnom Penh, Cambodia’s current wetland configuration in sustainably treating sewage discharge, with a specific focus on Boeng Cheung Ek, the 1,300-2,000 ha natural wetland to the south of the city. It is important to recognize that Boeng Cheung Ek also is a significant agriculture and aquaculture resource, home to a peri-urban community, and has a role in flood mitigation for Phnom Penh. Because Boeng Cheung Ek receives wastewater, the potential health risk to those living on the wetland and those consuming food stuffs from the wetland (either the peri-urban community or the population purchasing the food stuffs from a market) must be considered.
Under the IFS project, team members from Royal University of Phnom Penh, Asian Institute of Technology, Chiang Mai University, and Buffalo State showed that Boeng Cheung Ek was effective in treating the city’s waste before it reaches the Mekong/Bassac River system; levels of Zn, Cu, and Cr in the vegetables and fish from the wetland generally do not pose a high health risk (with the exception of Cr for children eating fish at one sample site); consumption of snails by children showed a higher risk with respect to Cr; fish and snails were infected by Opisthorchis viverrini, a liver fluke parasite. This parasite can be passed to humans when they eat undercooked fish. It was concluded that risk management related to certain aspects of food stuff consumption (e.g. education on proper cooking of fish, filtering or boiling water, limiting children’s consumption of snails) could be developed through a community outreach program.
An important aspect of this project has been the training and interaction between undergraduate and graduate students from Asian and U.S. universities.
Images related to this project can be viewed at http://view.buffalostate.edu/main.php?g2_itemId=36315