An Integrated Perspective for Urban Water Management 57
cient treatment options, such as membrane bio-reactors, and relatively simple technologies, such as soil aquifer treatment (Essandoh et al., 2009) and decentralized wastewater treatment systems (BORDA, 2012). The low-cost and low-energy requirements of these technologies are well suited to conditions in developing countries, and open up opportunities for communities to consider reuse, recycling, and cascading use. In many cases, innovative technologies are being hindered by old regulations such as building codes and health codes. During a workshop in Nairobi with stakeholders, representatives of the Nairobi City Council raised the need to revise building codes to permit such technologies as urban rainwater harvesting and greywater separation (ICLEI, 2012a). In many cases national codes, such as health codes that often date to the colonial era, will have to be revised.
Box 2.10
Decentralized Wastewater Treatment System as an Effective Technology to Improve Sanitation: Trapeang Sab Commune, Cambodia In the Trapeang Sab Commune, the main town was rapidly urbanizing and its traditional sanitation practices were no longer effective. The untreated wastewater being released in increasing volumes in the commune was becoming a hindrance to development because of groundwater pollution and public health issues. The decentralized wastewater treatment system (DEWATS) was implemented to serve 250 households and small businesses with a capacity of 100 cubic meters per day. The project had a total project cost of US$50,200. The system consists of a primary settling unit, an anaerobic baffled reactor, an anaerobic filter, and a discharge pipe. An operator was contracted by the Commune Council to be responsible for general operations and maintenance of the DEWATS. The treated effluent is in compliance with the Cambodia Ministry of Environment’s regulations for wastewater effluent discharged into public waters and sewers (chemical oxygen demand < 100 milligrams per liter and biological oxygen demand < 80 milligrams per liter). The Trapeang Sab DEWATS discharges effluent with a chemical oxygen demand of 94 milligrams per liter and a biological oxygen demand of 46 milligrams per liter. Total coliform has not been measured, but similar technologies such as waste stabilization ponds and constructed wetlands report total coliform removal of 97 percent. Source: IWA Water Wiki, 2012.