Study On The Denitrification Mechanism Of Anaerobic Ammonia Oxidation Coupled With Sulfur Autotrophic Short-cut Denitrification Process In The Treatment Of High-salt Wastewater

A large amount of saline wastewater is discharged in the process of seafood processing,aquaculture industry,pickling and other industrial processes,which brings great challenges to the protection and treatment of the water ecological environment.A biological strategy that combining marine anammox and sulfur-driven autotrophic denitratation?ASAD?process is proposed to treat N-rich saline wastewater in this work.During 169 days long-term operation of sequence bath reactor?SBR?,the effect of S₂O₃^2--S/NO₃^—N?S/N?value on the nitrogen removal performance of the ASAD process was investigated.When the S/N value was at 2.2,ammonium removal rates?ARR?and nitrate removal rates?NRR?respectively reached to 0.353 kg N/?m³·d?and0.355 kg N/?m³·d?.The total nitrogen removal efficiency?TNRE?was about at 99%with 98%of the nitrogen was generated by the anammox process.High-throughput sequencing technology was used to explore the microbial diversity and structural in this SBR.With the increase of S/N value from 0 to 2.2,3.2,and 4.6,the relative abundance of the Planctomycetes decreased from 33.9%%to 24.2%,17.0%,and 9.1%;and the relative abundance of the Proteobacteria increased from 22.8%To 36.8%,48.6%and 61.4%.Candidatus Scalindua?MAB?accounted for more than 92%of the Planctomycetes;Candidatus Thiobios and Sedimenticola,sulfur oxidization bacteria?SOB?in the marine ecosystem,those relative abundance increased from 0.1%to10.7%,19.9%,and 29.9%.Batch test A?BT-A?indicated that the maximum sulfate accumulation efficiency?SAE?gradually decreased from 96.7%to 79.1%and 70.3%with S/N value increased from 2.2 to 3.2 and 4.6.Batch test B?BT-B?was carried out at the optimal S/N value of 2.2,and the denitratation efficiency of SAD process(DE_SAD)and ASAD process(DE_ASAD)was respectively up to 62.4%and 98.3%.The synergistic effect of anammox process and SAD process enhances the nitrogen removal efficiency of the whole system.Key enzymes and modules in sulfur metabolism and nitrogen metabolism were analyzed based on metagenomic sequencing.In the sulfur metabolism pathway,thiosulfate oxidation through the SOX system?M00595?accounted for 7.2%,the gene abundance of sulfate reductase?EC:2.7.7.4?,PAPSS?3'-phosphoadenosine5'-phosphosulfate synthase,EC:2.7.1.25?and cysK?cysteine synthase,EC:2.5.1.47?were 42206 hits,24948 hits and 26044 hits,respectively.Hydrazine dehydrogenase?HDH,5520 hits?and hydrazine synthase?HZS,3404 RPKM?were key enzymes in anammox process.The genes abundance of nitrate reductase up to 119384 hits,was much higher than that of nitrite reductase?22119 hits?,proved that it was feasible to accumulate nitrite through SAD process.