| The continuous influent step-feed anoxic/oxic reactor and step-feed Sequencing Batch Reactor were conducted for treating municipal wastewater at Beishiqiao sewage purification center in Xi'an. The removal effect of the organic matter, the characteristic of nitrogen removal and transformations of various pollutants in the reactor is mainly discussed in this study.The results of continuous influent anoxic/oxic reactor as follows: The design influent flow is 160L/h and splitting to four points in the ratio of 4:3:2:1, the A/O volume ratio is set on 1:3 for each pass. 50% rate of return activated sludge (RAS), 7.5-hour hydraulic retention time (HRT)and 12-day sludge retention time (SRT). With the conditions, the average removal efficiency of TCOD, SCOD, NH3-N, TN and TP can reach to90.31%, 81.53%, 97.24%, 66.29% and 80.13%.The results of sequencing batch reactor as follows: The design influent flow is 5L in a period and splitting to three points in the ratio of 4:3:3 and 12-day sludge retention time(SRT), 18-hour hydraulic retention time (HRT). Under the conditions, the average removal efficiency of TCOD, SCOD, NH3-N, TN and TP can reach to 91.05%, 85.03%, 97.79%, 68.29% and 83.73%.Batch experiments are operated for the continuous influent anoxic/oxic reactor to determine the specific oxygen uptake rate, the specific ammonium uptake rate and the specific denitrification rate. The results are 35.09 mgO2/gMLVSS·h, 5.81 mgNH3-N/gMLVSS·h and 21.22 mgNO3--N/gMLVSS·h respectively. They show that the activated sludge has high activity in the mixed liquid.In conclusion, the two types of step-feed process are an effective technology of nutrient removal for municipal wastewater treatment. Because of the differences in HRT between the continuous influent step-feed anoxic/oxic reactor and step-feed Sequencing Batch Reactor, the removal efficiency of the latter is better than that of the former.
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