The Characteristics Of Activated Sludge Respirogram In The Process Of Temperature Decrease

At present,the main process of sewage treatment plant sewage treatment is activated sludge process.The activity of activated sludge microorganism is directly related to the sewage treatment effect of sewage plant,and the temperature affects the activity of microorganisms to a great extent,which affects the treatment efficiency of sewage treatment plant.The low temperature condition in winter can inhibit the activity of activated sludge microorganism,which leads to the microorganism entering the dormant state and even losing,thus affecting the removal effect of pollutants in wastewater treatment plant.In order to study the treatment capacity of activated sludge system,the dormancy and loss of microorganism and the variation of microbial population under the low temperature in winter,and to provide a theoretical basis for the stable operation and operation regulation of the sewage treatment plant in winter,in this study,the low temperature condition of the sewage plant was simulated,and the effluent quality and the respirogram of the activated sludge were studied.The results show as follow:?1?During the temperature reduction process,the critical temperature for the removal of organic matter and nitrogen and phosphorus removal efficiency were 10?and 8?,respectively.The system is restored to the original temperature operation after a brief low temperature impact,and microbial activity and sewage treatment capacity can also be quickly restored.?2?With the gradual decrease of temperature,the field condition autotrophic bacteria respiration rate OUR_n,heterotrophic respiration rate OUR_c and total respiration rate OUR_enc were decreased gradually,indicating that the decrease of temperature could lead to the decrease of microbial activity and the decrease of the sewage treatment capacity.?3?When the field condition OUR decreased and the standard condition OUR did not change obviously,it indicated that the microorganism was in a dormant state.At this time,the increasing temperature can activate the activity of microorganism rapidly.When the standard condition OUR significantly reduced,indicating the loss of micro-organisms.?4?With the decrease of temperature,the field condition respiration ratio of autotrophic bacteria gradually decreased and the heterotrophic bacteria respiration ratio increased gradually,which indicated that the adaptability of heterotrophic bacteria to low temperature was stronger than that of autotrophic bacteria.When the temperature decreased from 20?to 10?,the standard condition respiration ratio of autotrophic bacteria and heterotrophic bacteria were kept stable,indicating that the intrinsic activity of the activated sludge microorganism remained stable,and the decrease of temperature had little effect on the physiological characteristics of sludge at this stage.The temperature decreased from 10?to 8?and 5?,the standard condition respiration ratio of autotrophic bacteria began to reduce and the heterotrophic bacteria respiration ratio began to increase,indicating that low temperature on the microbial population structure had a certain impact,autotrophic bacteria loss is serious,also showed that the heterotrophic bacteria were more adaptable to the low temperature than the autotrophic bacteria.?5?Under low temperature condition,the addition of calcium chloride to the reactor can increase the autotrophic bacteria respiration rate OUR_n and the heterotrophic bacteria respiration rate OUR_c and increase the activity of autotrophic bacteria and heterotrophic bacteria.So it can be considered that adding calcium chloride to the actual operation of the sewage treatment plant in winter to improve the sewage treatment effect of the activated sludge system.Moreover,the addition of calcium chloride can reduce SVI,increase the average particle size of sludge and improve the settling effect of activated sludge.