STUDIES ON THE PURIFICATION AND RECLAMATION OF WASTE-WATER FROM A MEDIUM-SIZED CITY BY AN INTEGRATED BIOLOGICAL POND SYSTEM

The feasibility of an inexpensive wastewater treatment system is evalu ated in this study. An integrated biological pond system was operated for more than 3 years to purify the wastewater from a medium-sized cit y, Central China. The experiment was conducted in 3 phases with differ ent treatment combinations for testing their purification efficiencies . The pond system was divided into 3 functional regions: influent puri fication, effluent upgrading and multi-utilization. These regions were further divided into several zones and subzones. Various kinds of aqu atic organisms, including macrophytes, algae, microorganisms and zoopl ankton, were effectively cooperating in the wastewater treatment in th is system. The system attained high reductions of BOD5, COD, TSS, TN, TP and other pollutants. The purification efficiencies of this system were higher than those of most traditional oxidation ponds or ordinary macrophyte ponds. The mutagenic effect and numbers of bacteria and vi ruses declined significantly during the process of purification. After the wastewater flowed through the upgrading zone, the concentrations of pollutants and algae evidently decreased. Plant harvesting did not yield dramatic effects on reductions of the main pollutants, though it did significantly affect the biomass productivity of the macrophytes. The effluent from this system could be utilized in irrigation and aqu aculture. Some aquatic products were harvested from this system and so me biomass was utilized for food, fertilizer, fodder and some other us es. The wastewater was reclaimed for various purposes.