| Sewage treatment on the plateau has difficulties such as low temperature,large temperature difference between day and night,strong ultraviolet radiation interference,relatively low carbon,nitrogen in domestic sewage,and high alkalinity.At present,activated sludge method is mainly used for plateau sewage treatment to treat sewage,which consumes a lot of energy,while plateau sewage treatment generally has a small amount of treatment.And the waste activated sludge is difficult to degrade,which is likely to cause secondary pollution.Targeted compound bacteria can treat plateau sewage of different magnitudes more flexibly with less energy consumption and pollution,and are more suitable for the plateau sewage treatment environment.In this study,heterotrophic nitrification-aerobic denitrifying bacteria were screened from sludge from different sources,and a composite denitrification inoculum suitable for plateau areas was constructed,and the environmental adaptation of the denitrification composite inoculum constructed from different sources was adapted to the environment.The research has been carried out to provide a reference for the subsequent development of the plateau compound microbial agent.For the first time,the experiment screened two groups of six heterotrophic nitrifying-aerobic denitrifying bacteria from indoor activated sludge and outdoor sewage treatment pool sludge in plateau areas.Among them,the indoor bacteria were named SN1,SN5,SN10,and the outdoor bacteria were named SW3,SW5,SW6.And based on the strains screened,two groups of six denitrification compound bacteria were constructed(SN1+SN5,SN1+SN10,SN5+SN10 and SW3+SW5,SW3+SW6,SW5+SW6).The experiment performed 16 S r DNA sequencing on six bacteria,and compared the NCBI database to construct a phylogenetic tree of six bacteria.The experiment conducted research on the denitrification effect of the constructed compound bacterial agent under different temperature,p H,carbon-nitrogen ratio,and ultraviolet radiation conditions.Based on the research,the environmental adaptability of the compound bacterial agent was evaluated.The research obtained the following results:1.For the three kinds of indoor compound bacteria,the highest working condition of ammonia nitrogen removal rate is 20℃ and the lowest working condition condition is 10℃.Except for 10℃ temperature conditions,the removal rate of nitrate nitrogen exceeds 90% within 48 hours.The highest operating condition of nitrite nitrogen accumulation is 20℃,and the lowest is10℃.The compound bacteria reaches the exponential growth phase in a heterotrophic nitrification medium and a denitrification medium in 12 hours.For the three outdoor compound bacteria,the highest working condition of ammonia nitrogen removal rate is 15℃,and the lowest working condition is 10℃.Except for the 10°C temperature condition,the removal rate of nitrate nitrogen exceeded90% within 48 hours.The highest condition of the cumulative amount of nitrite nitrogen was 15°C and the lowest was 10°C.The compound bacteria reaches the exponential growth phase in the heterotrophic nitrification medium and denitrification medium in 24 hours.At 10°C,the heterotrophic nitrification and aerobic denitrification reactions of the indoor compound bacterial agent basically stop,and the denitrification function of the outdoor compound bacterial agent is greatly affected,but it can still proceed slowly.2.For the three indoor compound bacteria,the highest working condition for ammonia nitrogen removal rate is p H 9 and the lowest working condition is p H 5.Except for the working condition of p H 5,the removal rate of nitrate nitrogen exceeds 90% within 48 hours.The highest operating condition for the accumulation of nitrite nitrogen is a p H of 9 and the lowest is a p H of 5.The compound bacteria reaches the exponential growth phase in a heterotrophic nitrification medium and a denitrification medium in 12 hours.For the three outdoor compound bacteria,the highest working condition of ammonia nitrogen removal rate is p H 11,and the lowest working condition is p H 5.Except for the working condition of p H 5,the removal rate of nitrate nitrogen exceeds 90%within 48 hours.The highest operating condition for the accumulation of nitrite nitrogen is p H 11,and the lowest p H is 5.The compound bacteria reaches the exponential growth phase in the heterotrophic nitrification medium and denitrification medium in 24 hours.When the p H is 5,the aerobic nitrification and heterotrophic denitrification reactions of the indoor and outdoor compound bacteria are basically stopped.3.For the three indoor compound bacteria,the heterotrophic nitrification ability is basically lost after UV treatment,and the ammonia nitrogen removal rate is less than 5%.Ultraviolet radiation has a strong killing ability for indoor compound bacteria.The decomposition of a small amount of ammonia nitrogen may be converted into ammonia gas and separated from the liquid.The OD600 value in the heterotrophic nitrification medium is extremely small,and a small amount of bacteria may not be completely killed.Nitrogen is also less removed,possibly due to the migration and transformation of nitrogen.After UV treatment,in the first 12 hours of outdoor compound bacteria,the removal rate of OD600,ammonia nitrogen,and nitrate nitrogen are all low.In 24 hours,the removal rate of OD600,ammonia nitrogen,and nitrate nitrogen has a rapid increase process,UV radiation may can promote the denitrification ability of outdoor compound bacteria.4.For the three indoor compound bacteria,the highest working condition of ammonia nitrogen removal rate is a carbon-nitrogen ratio of 20,and the lowest working condition is a carbon-nitrogen ratio of 5.Except for the carbon-nitrogen ratio of 5 operating conditions,the removal rate of nitrate nitrogen exceeds 90%within 48 hours.The highest operating condition of the nitrite nitrogen accumulation rate is a carbon-nitrogen ratio of 20,and the lowest is a carbon-nitrogen ratio of 5.The compound bacteria reaches the exponential growth phase in a heterotrophic nitrification medium and a denitrification medium in 12 hours.For the 3 kinds of outdoor compound bacteria,the highest working condition of ammonia nitrogen removal rate is a carbon-nitrogen ratio of 20,and the lowest working condition is a carbon-nitrogen ratio of 5.The carbon-nitrogen removal ratio is 20 working conditions,and the nitrate nitrogen removal rate exceeds 90% within 48 hours.The highest operating condition of the nitrite nitrogen accumulation rate is a carbon-nitrogen ratio of 20,and the lowest is a carbon-nitrogen ratio of 5.The compound bacterial agent reaches the exponential growth phase in the heterotrophic nitrification medium and denitrification medium in 24 hours.When the ccarbon-nitrogen ratio is 5,the aerobic nitrification and heterotrophic denitrification reactions of the indoor compound bacterial agent proceed slowly,and the denitrification function of the outdoor compound bacterial agent is also greatly affected,but the effect is relatively small. |
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