Two-phase anaerobic digestion process for treating high concentration sulfate-organic wastewater with jet-loop anaerobic fluidized bed reactor
Jet-loop anaerobic fluidized bed(JLAFB) was designed as a new anaerobic reactor.Two-phase anaerobic digestion process with JLAFB and AGSFB(anaerobic granular sludge fluidized bed) as acidogenic phase(or sulfate-reducing phase) and methane-producing phase,respectively,was used to treat high concentration sulfate-organic wastewater.With the successful culture of acid-tolerant sulfate reducing anaerobic granular sludge,the process successfully separated sulfate reducing bacteria(SRB) and methane producing bacteria(MPB) in different phases,and avoided substrate competition inhibition on MPB by SRB.When influent SO~~(2-)__4 loading rate was up to 12.0 kg SO~~(2-)__4·m~(-3)·d~(-1),the sulfide concentrations of JLAFB and AGSFB reactors were 78.3 mg·L~(-1) and 92.4 mg·L~(-1),respectively,that were far less than 200 mg·L~(-1) of inhibition value,which avoided the accumulation of sulfide and toxicity inhibition on microorganisms in reactors.When the influent COD and SO~~(2-)__4 loading rates during smooth operation were 26.0 and 8.5 kg SO~~(2-)__4·m~(-3)·d~(-1) respectively,the total removal efficiency values of COD and SO~~(2-)__4 were 86.9% and 97.6% respectively.The optimal process conditions of the treating system were:influent COD/SO~~(2-)__4 ratio3.0,influent alkalinity was 400—500 mg·L~(-1),aeration gas flow rate and hydraulic recycle ratio of JLAFB were 0.04 L·min~(-1)and 5∶1 respectively.