Effects of sludge biochar on the long-term stability of aerobic granular sludge in low C/N wastewater
Aerobic granular sludge technology is a promising biological method for wastewater treatment.Sludge biochar was used as a carrier to cultivate aerobic granular sludge,and the subsequent long-term operational stability of the mature aerobic granules was investigated under the condition of carbon to nitrogen ratio(C/N)from 10 to 4.The results showed that the mature aerobic granular sludge carried by biochar was more compact in structure and not easy to disintegrate.The aerobic granular sludge had good settling ability with SVI30 of 50mL/g and performances with the removal efficiency of COD and TN more than 90%and around 70%,respectively,through the whole operation period,although they were suffered from strong proliferation of filamentous Thiothrix.High-throughput sequencing analysis showed that the aerobic granular sludge carried by the sludge biochar had lower microbial diversity,but they had higher dominance of denitrification functional genera,which enhanced their nitrogen removal performance.Overall,our study demonstrated that adding sludge biochar to cultivate aerobic granular sludge may improve nitrogen removal performance and the long-term operational stability of the system,which is favorable for the treatment of high ammonia-nitrogen wastewater under low C/N conditions.
aerobic granular sludgesludge biocharmicrobial community structurelong-term operational stability