ABSTRACT
Waste generation rate is greater in developed than in developing countries, with per capita estimates varying from 1.43–2.08 and 0.3–1.44 kg/day, respectively; with the organic fraction accounting for 55%–60% in developing countries, more than twice the value in some developed countries. Waste stabilization ponds often form part of a decentralized domestic wastewater treatment system in developed and developing countries alike, where they are main treatment and/or posttreatment. In temperate regions, their use is often restricted to tertiary and final polishing following aerobic or anaerobic treatment. Ponds can be designed to receive wastewater directly from surrounding populations, and septic tanks effluents from afar. Aerobic ponds are completely mixed and aerated using mechanical systems, such as motor-driven surface aerators, to bring about aerobic conditions to all parts of the pond and to increase the microorganism–waste contact. The most common global application of anaerobic treatment technology is in digestion of solid wastes and slurries.
