| At present,biogas digester,septic tank,constructed wetland,land percolation and other biological treatment methods are mostly adopted for domestic sewage treatment in rural areas of China,these methods have the advantages of low energy consumption,small secondary pollution and convenient operation and management.But the winter temperature is low in the rural areas of northern China,The biological treatment method is seriously affected by low temperature,and the sewage treatment efficiency is greatly reduced,resulting in substandard effluent.Therefore,the screening and domestication of psychrotrophs with high biodegradability and high biodegradability at low temperature and room temperature is of great significance for the rural domestic sewage treatment in northern China.Based on activated sludge as psychrotroph source,low temperature resistant activated sludge was obtained through repeated low temperature acclimation,and several psychrotroph strains were isolated and screened from the activated sludge,which had high efficient degradation of organic matter in sewage,identifying the dominant strains and conducting molecular biology identification,then the effects of mixed bacteria was studied and the bacterial agent was made.The chemical oxygen demand?COD?of water crops in the farmland irrigation water quality standard?GB5084-2005?in China was taken as the standard(COD?150mg?L-1),to investigate the treatment of rural domestic sewage by low temperature acclimated sludge and psychrotrophs.The research is mainly divided into the following contents:?1?The activated sludge was taken from a sewage treatment plant in jilin as the sample source,and acclimated in low temperature.When the acclimated sludge was used to treat actual rural domestic sewage,The COD removal rate of the actual rural domestic sewage at 8?was 84.97%,the lowest effluent COD was 89.51mg?L-1,and the shortest treatment period of reaching the farmland irrigation water quality standard in China was 8 days.In the middle integrated simulator of sewage treatment,the simulated rural domestic sewage was treated with sludge for 30 days.The average effluent COD was 97.53mg?L-1,and the highest COD removal rate was 88.44%,the average removal rate was 86.26%.?2?A total of 62 psychrotroph strains were Isolated from activated sludge which was acclimated at low temperature,through the observation of the treatment of artificial sewage,eight strains with good treatment effect were selected,respectively was H-7,H-10,H-29,H-30,H-33,H-36,H-40 and H-54.Observation of colony morphology,physiological and biochemical analysis and 16SrDNA sequence analysis of these 8 strains were performed,after final identification:H-29,H-33,H-36belonged to pseudomonas genus;H-7,H-30,H-54 belonged to raoultella terrigena;H-10 belonged to rahnella inusitata;H-40 belonged to serratia liquefaciens.?3?The COD removal capability of single psychrotroph and mixed psychrotrophs of simulated rural sewage treatment was compared.The initial COD of simulated rural sewage was 721.5mg?L-1,the highest COD removal rate of simulated rural sewage by pseudomonas H-30 was 88.6%at 10?,and the highest COD removal rate of actual domestic sewage was 94.12%after eight strains of psychrotrophs were mixed in proportion to volume ratio of H-7?H-10?H-29?H-30?H-33?H-36?H-40?H-54=2?1?4?4?4?1?1?1.?4?The preparation effect of psychrotroph was studied.Diatomite was used as adsorbent,and adsorbed with the activated mixed bacterial liquid of psychrotrophs to make bacterial agent.The results showed that the best treatment effect of simulated rural domestic sewage was achieved when the diatomite suspension of 0.04g?mL-1was adsorbed in a shaking table at 20?for 84h with 3mL of the best mixture of bacteria,the COD removal rate was 58.05%,on the 120 hours.After making the bacterial agent according to the optimal conditions,treatment of actual rural domestic sewage at 10?,when the dosage of bacterial agent was 0.02g?mL-1,the highest COD removal rate was 83.61%,and the effluent COD was 92.45mg?L-1. |
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