Experience and practice of the treatment and utilization of sewage and organic wastewaters using stabilization ponds with artificial or semi-artificial ecosystems in China are described. The eco-ponds being used in China are different from those with symbiotic algae/bacteria systems in that the former consist of not only bacteria and fungi as decomposers and algae as producers, but also fish, shrimps, shellfish, ducks, geese, etc. These are consumers at different trophic levels in food chains or food webs in the pond communities where fish farming and/or duck and geese raising takes place. The eco-ponds are characterized by low capital and operation costs, energy savings, high removal efficiencies for a wide variety of pollutants, and considerable Drofits that can be gained from comprehensive utilization of wastewaters as recoverable resources.
Some typical eco-ponds for treatment and utilization of municipal and industrial wastewaters, such as fish farming ponds in Changsha, (Hunan), and in Ehcheng, (Hubei), hydrophyte ponds in Shaoxing, (Jejiang) and in Shijiazhuang, (Hebei), and treatment/storage lagoons with ecosystems are described in detail.
The concept of ecological systems for treatment and utilization of wastewaters, and the various ecological wastewater treatment and utilization systems (EWTUS) available for different regions, are also discussed in this paper.