Isolation Of Psychrotrophs And Their Application To Treatment Of Low-Temperature Sewage

Low temperature may cause low sfficiency of sewage treatment in winter of cold area.As temperature drops to around 10℃,the mesophilic microorganisms would lose most ability to metabolize allogenic materials,thus the principal source to decompose organic wastes in sewage is psychrotrophs which only exist a little amount in natural conditon.Some study results has shown that the treatment efficiency could be improved significantly by adding psychrotrophs into the activated sludge,unfortunately the effect could be decreased with the time being,this has made great consumption by adding psychrotroph repeatedly during the low-temperature sewage treatment.4 strains of high organic degradation psychrotrophs and (A2, A12, A21, A30) and 2 strains aerobic denitrifiers(B2,B3)were isolated from activated sludge.4trains of psychrotrophs were identified as Flavobacterium,Bacillus,Comamonas and Micrococcus.In static test,the removal rates of 4 strains of high organic degradation psychrotrophs to COD were 59.33%, 47.74%, 35.70% and 31.21% ,the removal rates of NH₄^-1-N were 44.37%, 54.22%, 41.38% and 49.74%. Two cold-adapted aerobic denitrifiers are facultative bacteria.In high and low concentrations of dissolved oxygen ,B2 and B3 have high removal rates of nitrate nitrogen, with the initial concentration of nitrate nitrogen increased, the removal rates of nitrate nitrogen increased too,pH 7.0 7.5 was good for growth of aerobic denitrifiers.So the cold-adapted aerobic denitrifiers are suitable for domestic wastewater treatment (pH7.0 8.0).In order to prevent the loss of psychrotrophs and engineering application, we used SPF as carriers.the adding amount of carriers is 30% v/v of the volume of the experimental equipment.After adding carriers to cold A/O reactor and running 40d, its treatment effect had significant improvement, the average removal rates of COD, NH₄^-1-N, TN reached 70%, 70% and 50%, suspended solids in the water was 20mg/L, while the average removal rate of the other reactor were only 50%, 57%, 40%.Above all,low-temperature sewage treatment system could sustain a certain amount of psychrotrophs by adding immobilized psychrotrophs to efficiently decompose the ogranic compounds,so as to improve the treatment effect of sewage in cold area.It have immensity meaning to the remove of sewage in the cold temperature field because this technique breached the limit of temperature and widen the scope of cold-temperature sewage remove.It also provided one way to research the cold-temperature sewage removing by microbiology.