Study On The Treatment Of Copper Wastewater By Sulfate Reducing Bacteria Granular Sludge In Anaerobic Baffled Reactor

The environmental pollution become worse and worse when more and more wastewater is produced rapidly with the economic development. The treatment technology with anaerobic microorganism which is on the representation of SRB has a lot of advantages, such as reducing the pollutant completely, lower cost and none of the second pollution and it becomes the hotest wastewater treatment at present. According to the structural characteristic of ABR, it has a lot of advantages, such as simple structure, lower price, strong ability of retaining sludge, and high stability and so on, and it has became one of the hot topic of anaerobic reactor study nowadays. On the bases of analyses of principle and applications of ABR and present researches on the heavy metals treatment by SRB, the operation characteristic and performance of treating copper wastewater with SRB granular sludge which was domesticated in ABR were studied systematically in the paper.The running characteristics during the set-up of ABR and performance changes of granule sludge were analyzed using laboratory-made anaerobic baffled reactor. The experiment results showed that, when the reactor started at a constant temperature of 35℃with inoculated anaerobic granular sludge and simulated synthetic wastewater as substrate,the whole start-up period was 57 days, and the maximum volume loading rate was up to 4.9kgCOD/(m3·d), and the removal rate of COD and SO42- stabled above 91%. And after the set-up, the VSS/TSS of granule sludge in the first and second compartments more than that of inoculated sludge and the granule sludge could still attain high biological activity and fine settlement property.Later, the effect of various pH, SO42- and Cu2+ concentration on the performance of sulfate reducing bacteria granular sludge treating COD, SO42- and Cu2+ were investigated by intermittent experiments in this paper. The results indicated that, (1) The SRB granular sludge would be likely to enter into the best operative state when pH was equal to 6~8. Besides, the maximum SO42- removal rate was 91.8%, the removal rate of COD was 83.2% to 90.5% and the maximum Cu2+ removal rate was over 91.6%. (2) The SRB granular sludge would be likely to enter into the best operative state whenω(COD)/ω(SO42-) was equal to 2 with the mass concentration of SO42- being 2000mg/L. Besides, specific methanogenic activity was 406.2mL/(g·d), the maximum SO42- removal rate was 93.4% and the maximum Cu2+ removal rate reached 97.1%, at the same time the removal rate of COD was positive correlation with the SO42- removal rate. (3) When the mass concentration of Cu2+ was equal to 10mg/L, the maximum content of methane produce was 58.3mL/h and the maximum COD removal rate was 90.5%. But the maximum SO42- removal rate (91.9%) presented at Cu2+=10mg/L. The removal rate of Cu2+ became stabled over 98% while mass concentration of Cu2+ was lower than 35mg/L.At last, the operation characteristic and performance of treating copper wastewater with SRB granular sludge by ABR were studied. The results indicated that, (1) At the moment of changing the SO42- concentration (the SO42- concentration fell from 2000mg/L to 500mg/L, then increased from 500mg/L to 2000 mg/L ), the DS concentration ranged from 51mg/L to 246mg/L which is lower than the deadly concentration. Besides the Cu2+ removal rate was over 95.1% and the SO42- removal rate ranged from 83.1% to 92.7%. (2) When HRT was shorten from 20h to 7h with the COD volume load increased from 4.8 kgCOD/(m3·d) to 13.7 kgCOD/(m3·d), the removal rate of COD, SO42- and Cu2+ as well as DS concentration decreased steadily. (3) The removal rate of Cu2+ became stabled over 90% and the effluence SO42- concentration was from 266mg/L to 562mg/L with the increasing Cu2+ concentration in influence. The COD removal rate was lower to 69% while Cu2+ concentration increased to 10mg/L. The tatal copper content of SRB granular sludge in the first compartment increased day by day and the copper of SRB granular sludge was mainly in organic sulfate fraction.The SEM showed that the inoculated granular sludge surface was rugged and species of microorganisms in it was single such as bacillus and coccus. On the other hand, the surface of domesticated SRB granular sludge was slippery, lacunaris and diversiform. There were various microorganisms in the domesticated SRB granular sludge and they were dense. The granular sludge grew up day by day with treating the copper wastewater. The surface of the granular sludge was so shaggy that it was disaggregated by the current in the ABR.