Study On Treatment Of High Concentration Sulfate Organic Wastewater By Anaerobic Upflow Granular Sludge Bed Biofilm Reactor

It is of great significance for the sustainable treatment of high-concentration sulfate organic wastewater to explore the new technology of integrated and efficient simultaneous carbon removal and desulfurization and resource recovery wastewater treatment.In this study,an anaerobic upflow granular sludge bed biofilm reactor（AUGSBBR）was used to develop an integrated granular sludge process system（AMOSRM）with simultaneous methane production,methane oxidation and sulfate reduction to treat simulated high concentration organic wastewater.The influent COD concentration was fixed at 2000 mg/L.The start-up characteristics of the system were studied.Under long-term operation conditions,by adjusting the influent sulfate concentration,the pollutant removal and gas production of the system under different carbon sulfur ratio(COD/SO₄^2-)were investigated.The results showed that when the concentration of SO₄^2-was 500 mg/L and the C/S ratio was4,the reactor had the best treatment effect,and the removal rates of COD and SO₄^2-were 96.7%and 99.7%,respectively.Meantime,the methane production of the system was 556.68 m L/d,and the volume fraction was 40.13%.Methane and hydrogen sulfide were found by gas composition analysis,and elemental sulfur was detected at the outlet position.Combined with batch tests,it was shown that the system realized better simultaneous methane and sulfate reduction.The extracellular polymeric substances（EPS）characteristics of sludge and biofilm in the reactor were directly related to methane production and sulfate removal efficiency.High-throughput sequencing showed that Methanothrix,Desulfovibrio,Sulfurospirillum,Methylocystis,Methylogaea and Caldisericum were the dominant functional bacteria in the system.In addition,the sludge granulation phenomenon in the sludge bed of the system was also found,and the macroscopic and microscopic characteristics,EPS characteristics and microbial community variation characteristics of granular sludge with different particle sizes were explored.Finally,the mechanism of AMOSRM in the system were discussed:the fermentation and methanogenesis mainly occurred in the sludge bed,and the sulfate reduction,methane oxidation and sulfur oxidation mainly occurred in the biofilm phase.Under the condition of COD/SO₄^2-=4,the hydraulic retention time was gradually shortened,and the granulation of sludge was realized.The macroscopic and microscopic characteristics,EPS characteristics and microbial community change characteristics of granular sludge with different particle sizes were explored.This process realized the coupling of methane production and methane oxidation with sulfate reduction under anaerobic conditions,and successfully developed an integrated granular sludge reaction system for simultaneous carbon and sulfur removal,which provided a new reference for the efficient treatment and resource utilization of high concentration sulfate organic wastewater..