Enhanced Nitrogen Removal Efficiency of Alkaline Biochar and Its Targeted Regulatory Mechanism.

Biological nitrogen removal is the main method of nitrogen pollution removal in sewage treatment plants. It has the advantages of low carbon and low cost. For the low carbon nitrogen ratio wastewater represented by municipal sewage, how to strengthen the denitrification functional flora and stabilize the biological nitrogen removal efficiency remains to be studied. In this study, two kinds of biochar carriers with enhanced nitrogen removal function were prepared by acid and alkali modification. And the enhanced denitrification nitrogen removal process was established. The research results showed that the total nitrogen removal rate of the system after adding biochar was increased by 7.29%~29.51% compared with the system with? out adding biochar. The nitrogen removal efficiency of acid and alkali modified biochar was improved by 19.37% and 29.55%, respectively, compared with that of the unmodified biochar system. The maximum nitrogen removal rate of alkali modified biochar system was 59.76%. In terms of electron transfer activity and nitrite reductase activity, the alkali-modified biochar enhanced system increased by 91.8% and 47.1%, respectively, compared with the non-added biochar system. At the same time, the high-throughput sequencing results showed that 67.3% of the bacteria involved in denitrification in the alkali-modi? fied biochar system. Bacillus and Thauera with denitrification were the dominant strains in the alkali-modified biochar system. The alkali-modified biochar promoted the growth of denitrifying bacteria more than the acid-modified biochar. Therefore, the target regulation of denitrification and nitrogen removal ability was established. [ABSTRACT FROM AUTHOR]