Research on Design Method of Improved Step-feed Multistage A/O Biological Treatment Process

WU Jie; LIU Jianjun; PAN Songqing; YANG Guang; XU Ying; LIN Xiangyu

doi:10.3969/j.issn.1003-6504.2017.03.019

Abstract：Thisstudy developed improved step-feed multistage A/O biological treatment process.Biofilm was introduced to this improved process and the recirculation in tradition step-feed A/O biological treatment process was left out.The improvement adapted to low C/N ratio of rural domestic wastewater andmet the needs of convenient maintenance and management as well as low operating cost.According to the basic relations of electron transfer in denitrification reaction,the fortnula of influent flow distribution of the improved step-feed multistage A/O biological treatment process was derived.The volume of every aeration and anaerobic pool was determined basing on principle of equal volumetric loading rate.Nitrogen removal rate of processing treatment would be predicted.The flow distribution ratio was related to C/Nratio of influent and the COD contents demanded by denitrification.However,the maximumnitrogen removal efficiency of the biological treatment system was also related to the numberof process segments in addition to the above mentioned.The more segments,the higher nitrogenremoval rate theoretically.The improved step-feed process was incessantly operated using the studied method of influent flow distribution with synthetic wastewater in different C/N ratio.The results showed that theoretical model could guide process design effectively and the improved process had the advantages of resistance to shock loading as well as convenient maintenance and management The TN removal rates were 50.5％ and 60％ on average,respectively,when CON/TKN ratios of influent were set at 3.75 and 7,with the effluent satisfactory to Grade I-B criteria of GB 18918-2002 steadily.