Nitrification And Nitrous Nitrification Research In Rotating Biological Contactor

Biological nitrogen removal was an important content of wastewater treatment research,and the conventional technics of nitrification-denitrification would limit its own development for the disadvantages,that were covering large aera,long reaction time and more energy consumption.Compared to the conventional technics of nitrification,people paied more attention to the single-reactor high activity ammonia removal over nitrite(SHARON)process,because it had series advantages,such as save a lot of time and energy,reduce excess sludge production and the dosage of alkaline substances.In light of the above advantages,short-cut nitrification had an important research value and became the former arts and crafts of many new technologies,for example,SHARON and short-cut nitrification—anammox(anaerobic ammonium oxidation).The experimentation used the rotating biological contactor to realize the short-cut nitrification process,and studied on the nitrification and short-cut nitrification,the main conclusions obtained as follows:(1)Considered both energy consumption and removal rate,the best rotational speed of RBC was 8rpm.When the concentration of ammonia was 200 mg/L and COD was 20 mg/L,HRT=3.16h,the removal rate of ammonia reached 92%,and the ammonia loading rate was 9.95 g/m~2·d.(2)The function of the steps of RBC was unlike in removing nitrogen:more than 70%of ammonia was removed by the first step,and the removal rate of the second step was about 12%,and the third step was 18%.(3)Start up the RBC system at low N/C proportion(N/C=5/100),the short-cut nitrification was realized after 64 days by constantly improving the N/C proportion and shortening HRT at the same time.The thickness of biofilm increased from 0.2cm to 0.5cm,and the colour of the bilfilm changed from light yellow to tawny during this process.The microscopic examination showed that the kinds of microbes decreased, the bell-form insect and branch-superposition insect etc.disappeared,and the bilfilm was connected by a lot of filamentous substance.The average ammonia removal rate was 69%,the average accumulative rate of nitrite was 79.6%,the max value achieved 95.8%,and the max ammonia loading rate of influent reached 7.46 g/m~2·d.(4)Restrict the DO of RBC by covering the reactor,the short-cut nitrification was realized by improving the concentration of influent COD from 50mg/L to 200mg/L while the gradient constant was 50mg/L,at the same time the other reaction parameters were:the concentration of ammonia was 200 mg/L,HRT=4.39h,the rotational speed of RBC was 8rpm,and the ammonia loading rate was 7.16g/m~2·d. Under these conditions the average ammonia removal rate was 91.4%,and the average accumulative rate of nitrite was 76.8%.