Reduction of organic contaminants and microbial communities in bioecological wastewater treatment system

Wastewater treatment is a key factor in controlling eutrophication of freshwater bodies. Nutrients discharge in wastewater can cause water quality problems such as eutrophication of freshwater bodies, decreased conservation and recreational value of water systems, and destruction of aquatic life. A pilot scale bioecological wastewater treatment system which consisted of a modified anaerobic\anoxic\oxic (A2O) system as a biological part and constructed wetland as an ecological part was developed to treat domestic wastewater (sewage). The study was carried out for pollutant removal performance of system and identification of microbial communities present in the system. The system showed excellent removal efficiency for chemical oxygen demand (COD) and organic nutrients such as ammonia, total nitrogen (TN) and total phosphorus (TP). Microbial count and distribution in different units of the bioecological system were dependent on associated factors such as, oxygen level, nutrients concentration and filtration from substrate. The bioecological system was proved to be quite effective in reducing total bacterial count (60%) as well as fecal coliform. The system offers simple operation, low energy consumption and high removal efficiency.   Key words: Wastewater, eutrophication, bioecological, constructed wetland, water quality.