Separation And Identification Of Psychrotrophic Ammonia Degradation Bacteria And Their Applications In Wastewater Treatment

Ammonia is one of the major pollutions of wastewater, caused deterioration of waterquality and massive death of aquatic life. Compare with physical and chemical methods,bio-treatment method is recognized as the most economic, effective and beneficial toenvironment, which is considered one of the most promising techniques. The microorganismplay an important role in the process of removing ammonia, the optimal temperature for mostof them to survive is30~35℃. But in cold season, it is hard for ammonia degradationbacteria to work effectively due to low temperature in water. Therefore, searching for thepsychrotrophic ammonia degradation bacteria which could work in low temperature showpractical significance.In the study, three predominant ammonia degradation bacteria A1, A4and A6wereisolated by the conventional microbial separation and purification methods at16℃and theirammonia removal rate ranged from58%to70%. Based on morphology, physiologicalcharacteristics,16S rDNA and phylogenetic tree analysis, A1, A4and A6were identified asAcinetobacter sp., Setnotrophomonas sp. and Pseudomonas sp., respectively.The influence of different environment factors on ammonia removal effect of the3strains was researched. The results indicated that the best temperature for the3stains was30~35℃, but its ammonia removal ability was also good at16℃; pH was alkaline; initialconcentration of ammonia of A1was300mg/L, but A4and A6were150mg/L; inoculumamount of A1, A4and A6were7%,5%and9%respectively; carbon source for A1, A6wassodium bicarbonate, A4was sodium succinate.Mixed flora was configured by the3stains and other strains, which have ammoniaremoval ability preserved in our laboratory. Orthogonal test was used to optimize theammonia removal conditions, and the ammonia wastewater treatment ability of the flora wasinvestigated by shake-flashing culture and magnifying devices at last. The result showed that:(1) Mixed flora H3which configured by A1, A4and A6has the best ability to removeammonia;(2) the optimal condition for H3at16℃were as follow: pH8.0; initialconcentration of ammonia,150mg/L; sodium bicarbonate,0.5g/L; inoculum amount,11%;proportion of A1, A4and A6,2:1:2. The ammonia removal rate reached to83.49%after10days treatment;(3) under the optimized condition, there was a positive treatment effect forsimulated ammonia wastewater and sanitary ammonia wastewater by H3. The ammoniaremoval rate of simulation ammonia wastewater reached85.37%after12days treatment at16℃, and the ammonia removal rate of sanitary ammonia wastewater reached75.88%after10days treatment between15~22℃.