Technological Optimization Of Sludge Reduction Based On T.tubifex Predation

T.tubifex, a kind of microfauna, the number and experiment conditions of which is easy to control, was used as the object of study. Using the T.tubifex's living habits fully, integrated with OSA sludge reduction technique, the sludge reduction rate was increased, the related technique parameters was optimized.Intermittent aeration was used in the T.tubifex predation area, the experiments showed the effect of sludge reduction is best when 10 minutes used as a cycle and the aeration time —settling time is 3 minutes—7 minutes, the sludge reduction rate can reach 0.79 mg-SS/ (mg-Tubifex ·d) .By the batch experiments , T.tubifex was used to reduce sludge combined with anaerobic digestion,the three influence factors including anaerobic exposure time, MLSS and temperature were studied, when the temperature is 26°C, with sludge anaerobic exposure time increase, the effect of sludge reduction became better, when anaerobic exposure time reach 40 hours, the sludge concentration become stable , sludge reduction rate become slowly ; T.tubifex was used to reduce sludge with different MLSS for 6 hours combined with anaerobic digestion ,the effect of sludge reduction is well correlated with MLSS; T.tubifex was used to reduce sludge with the same MLSS for 6 hours combined with anaerobic digestion , when the temperature are 30℃,37℃,45℃,55℃ etc, with the temperature rise, the effect of sludge reduction became better .The increasing rates of COD, NHU₄⁺-N and TP in water caused by the predation of microfaunas and anaerobic digestion. But the increased concentration did not overload the continuous activated sludge system. COD ,NH₄⁺-N and TP removals in the activated sludge process where microfaunas co-existed were not obviously influenced, because of no sludge discharge , TP removals ratio become less, in the modified activated sludge process: the T.tubifex predation combined with anaerobic digestion, the TN mean removal ratio was 30.9%, TP mean removal ratio was 56.4%, NH₄⁺-N mean removal ratio became less, only reached 87.5%, in the T.tubifex predation combined with anaerobic digestion technique, COD mean removal ratio is about 3%-5% less than referent technique and T.tubifex predation technique.The OUR(oxygen use rate ) was determined , in the T.tubifex predation combined with intermittent aeration technique, sludge activity for organic carbon oxidation (OUR_o) became a little less and sludge activity for nitrification increased (OUR_n) , and OUR_t increased. In the continue experiment of T.tubifex predation combined with anaerobic digestion technique,, the OUR_t was letter than referent technique, and was higher than T.tubifex predation technique,, and OUR_n was the best. The T.tubifex predation technique, and T.tubifex predation combined with anaerobic digestion technique, could influence the the sludge setteability, indicate the SVI rise.In the T.tubifex predation combined with anaerobic digestion technique, the effect of sludge reduction became better, could increase the sludge reduction rate. In the whole experiment process , sludge couldn't increase , sludge production yield coefficient was -0.016g-SS/g-COD. In the holding tank there were hydrolysis, ammonification, phosphorus releasing and denitrification.The biological phase observation showed the floc-forming bacteria were incompact in the system where T.tubifex predated, the kinds of protozoa and metazoan were less than referent system , and in T.tubifex predation combined with anaerobic digestion system, no protozoa and metazoan was observed.The BACLight staining showed when the anaerobic digestion was not for along time and was below 37 centigrade ,.the live bacteria ratio in the actived sludge didn't fall., but when it was 45 centigrade or 55 centigrade, the live bacteria ratio in the actived sludge rapidly fall , the cell lysised evidently. In T.tubifex predation combined with anaerobic digestion system, the live bacteria ratio in the actived sludge was a little higher than referent system .