Study Of Anaerobic Sulfate Reducing In The Alkali Absorption-biological Flue Gas Desulphurization Process

Biological flue gas desulphurization technology has attracted more and more researchers'interest recently. A study about the anaerobic sulfate reducing in the alkali absorption-biological flue gas desulphurization process was done here. SRB (Sulfate Reducing Bacteria) was used to treat the simulated alkali absorption effluent and an UASB (Upflow Anaerobic Sludge Blanket) reactor was used as the anaerobic reactor. The start-up of the UASB reactor and the optimal operation condition of technics were studied.An UASB reactor (effective volume=96L) was designed, installed and then used in this investigation.The UASB reactor was started at 12h HRT (Hydraulic Retentium Time) and 30±2℃temperature. Glucose was used as the carbon source, sodium sulfate was used to provide SO42- and the effluent pH was kept at 6.00±0.15 while the influent pH was in the period of 7.50-8.50. After 30d, the organic loading rate increased from 0.60kgCOD/(m3-d) to higher than 5.00kgCOD/(m3-d), the sulfate loading rate increased from 0.24kgSO42-/(m3·d) to higher than 1.65kgSO42-/(m3·d), and the removal of organic and sulfate were 85% and 70% respectively. The SEM(Scanning Electron Microscope) photographs showed that mature granular sludge had appeared in the reactor and it repreasented that the reactor was started successfully. The effects of HRT and COD/SO42" ratio on the whole process were studied. The research results showed:(1)The optimal COD/SO42- ratio was between 2.6 and 2.9, in this period, the organic removal reached 85%,the sulfate removal was higher than 60% and the effluent sulfate concentration was less than 250 mg/L; (2) The best HRT value was 12h.To study the operation performance of the reactor, the second start-up experiment and shock loading experiment were operated. After a shutdown of 20d, the reactor's organic loading rate, sulfate loading and the corresponding removal reached the level before outage in 7d. The results showed that the process could meet the demand of intermittent operation. The shock loading test showed that the reactor could endure the organic loading rate of 8.7kgCOD/(m3-d) and sulfate loading rate of 3.2kgSO42-/(m3-d) with the removal of 60% and 50% separately.