Efficiency of energy-saving of anaerobic-adding raw wastewater-intermittent aeration(Anarwia) process for treatment of piggery wastewater

The treatment effects of the anaerobic-adding raw wastewater-intermittent aeration(Anarwia), Sequencing Batch Reactor(SBR) and anaerobic-SBR process were compared. Among the three processes, anaerobic-SBR process was not technologically feasible to the treatment of piggery wastewater because of poor removal efficiency of chemical oxygen demand, ammonia nitrogen from wastewater and higher concentration of pollutant remained in the effluent. The treatment efficiency of Anarwia process could reach that of the SBR process with more efficient removal of chemical oxygen demand and ammonia nitrogen and relatively lower concentration of them in the effluent. Taking a plant treating 1200 t/d piggery wastewater as an example, the energy consumption of Anarwia process and SBR process was compared. As for the sludge yield and the oxygen demand that are process parameters interrelated energy consumption, the sludge yield and chemical cxygen demand by Anarwia process are 16.4% and 95.9% lower than those by SBR process. In addition, Anarwia process can produce 2784 m³/d biogas. Anarwia process increased energy consumption of pumping wastewater, and decreased that of aeration, sludge treatment, decanting and stirring, resulting in that the total energy consumption of Anarwia process was 81.0% lower than that of SBR process. Moreover, the energy consumed in Anarwia process could be completely compensated by electricity generated from biogas.