Small scale treatment systems

Abstract

Inadequate or improper collection and disposal of liquid waste leads to pollution of surface and groundwater and pose major threats to public health and community well being. The emergence of big cities and industries has typically demanded centralised collection, treatment and disposal systems for liquid wastes. Most cities in developed countries have reticulated sewerage systems which collect and treat the wastes to acceptable standards. In fact a majority of municipal authorities and public health engineers consider the reticulated sewerage system with a modern high technology treatment system and disposal facility as the only suitable approach to liquid waste for a municipal area. Such systems require continuous and plentiful supply of water along with all the capital intensive infrastructure necessary for treatment and these conditions are not always easily fulfilled. Developing countries and smaller more isolated communities find the cost of providing such facilities to achieve the necessary public health requirements prohibitively high. In rural and semi-rural and particularly remote areas a centralised system generally costs much more on a per capita basis than a locally based independent system of liquid waste .disposal. In this context there are now a variety of options for wastewater treatment, disposal and reuse. Such systems can produce an effluent quality equal to or better than a conventional treatment plant. The major concern for municipal authorities and public health engineers is to dispose of the waste with minimum nuisance and health problems and at a price that can be managed within capital and recurrent budgets. From the point of view of a local community there are questions of the affordability of the chosen system for them, but also wider and deeper issues of community development and control over technologies that have the potential to influence the dynamics, form and autonomy of the society into which they are introduced. There are now growing environmental and social pressures to consider all the possibilities for reusing wastes and to begin introducing systems which are of a sustainable nature. This paper will discuss the criteria to be considered in general in the process of selection of a particular technology and then explain a few technologies which are approved to be used in Western Australia