Alternative Technology for Urban Wastewater Treatment: Case Studies and Issues of Implementation and Sustainability

Abstract

Effective collection and treatment of urban and industrial wastewater is a critical problem in countries such as Sri Lanka and India. Current solutions to these problems have been dominated by “western” approaches such as centralized sewerage based on traditional design criteria and treatment using aerobic processes such as the activated sludge process. However, the solutions are expensive to construct and operate and pose technical and financial challenges for the operating authorities. This paper examines alternative concepts – such as distributed systems, re-use of treated wastewater and community participation and technologies – such as simplified sewerage, settled sewerage, septic tanks for primary treatment, anaerobic filters for secondary treatment and constructed wetlands for secondary and tertiary treatment for the collection and treatment of urban wastewater and describes their performance in various situations in Sri Lanka. It is concluded that these alternative approaches have been successful in a wide variety of applications. In particular, treatment to levels that permit re-use in gardening and vehicle washing has been achieved in several hotels. However, some issues related to long term-operation and maintenance remain to be resolved in the case of application to low-income settlements. Non-acceptance by professionals and decision makers due to limited knowledge about these systems, overly rigid interpretation of regulations and specifications and the lack of general guidelines relevant to Sri Lanka are some of the hurdles that must be overcome before these technologies are used more widely. The paper concludes with some suggestions for enhanced co-operation between Sri Lanka and India in the development and deployment of these technologies. The similarities in urban problems, climate, and socio-economic factors are such that successful duplication can be expected. Copyright ASCE 2004 World Water Congress 2003