[Pilot experiment on the treatment of the river wastewater by a step-feed biological contact process]

In the Dianchi Lake watershed, the Daqinghe River with the highest load of pollution was chosen as the treatment target, a new step-feed biological contact (SFBC) process was studied to treat the wastewater from the riverway. The pilot experiment was carried out through a winter dry season, a spring dry season and a summer rainy season. The results showed that the SFBC process was well-adapted to the variation of the river wastewater qualities. By adjusting the process parameters in different seasons, the removal rates of COD and TP could be stable at about 50% and 40% respectively; however, the removal rate of TN was influenced by the water temperature and DO greatly, and kept at about 20% when the process went to its stabilization. Seeding with activated sludge could accelerate the start-up of the equipment, but the whole treatment efficiency was not as good as that of the equipment without seeding but domesticating the microorganism in the river wastewater. However, along with the running of the SFBC process as well as the impact of the influent sediment from the river, the difference of the treatment efficiencies between the two equipments of whether or not seeding with activated sludge would disappear gradually.