Low-Cost and Low-Energy Wastewater Treatment Systems: A South African Perspective

An overview of waste-water treatment alternatives in South Africa is presented. A comparison of the capital, operating and maintenance costs of biological filters, bio-discs, stabilisation ponds and an extended-aeration-actiyated sludge system suggest that stabilization ponds may be regarded as a low cost, low energy waste-water treatment system. However, in some instances, due to legal and land requirements they are not appropriate. In these instances a number of interacting factors play a role in determining the lowest cost option. The capital construction and operating costs of constructed wetlands are similar to those of stabilisation ponds but due to lack of full scale operational information they are not yet widely used as a waste-water treatment system.