| The pharmaceutical wastewater which has complex composition,high COD concentration,low biodegradability,and high-salty characteristics,is one kind of the industrial wastewater that is difficult to be treated.The anaerobic biotechnology is often used to treat pharmaceutical wastewater in engineering practice to reduce the cost.The formation of anaerobic granular sludge which ensures the high organic loading rate operation and stable performance of anaerobic reactor is decided by many factors.It is even more difficult to gain natural granular sludge for the chemical synthetic-based pharmaceutical wastewater with biological toxicity and inhibition.In this study,PVA-gel beads were used as bio-carriers.The start-up and operation performance of PVA anaerobic granular sludge reactor treating chemical synthesis-based pharmaceutical wastewater were studied.Meanwhile,UASB reactor inoculated with conventional granular sludge,conventional granular sludge and activated carbon treated same pharmaceutical wastewater,and the operation performance was studied.The microbial characteristics of PVA granular sludge and conventional granular sludge were studied by means of scanning electron microscope and high throughput sequencing.The main research contents and conclusions are as follows:(1)After 17 days cultivation,embryonic PVA granules were obtained by mixing activated sludge and PVA-gel beads with volume ratio of 2.5:1.The UASB reactor was inoculated with embryonic PVA granules.After 30 days operation,acclimation to the pharmaceutical wastewater was completed.The volume loading rate was increased from1.2 kgCOD/(m~3·d)to 7.1 kgCOD/(m~3·d).The wastewater quality(COD=2540~5210 mg/L)fluctuated strongly.However,the COD removal efficiency was stabilized at about 70%with volume loading rate as 7 kgCOD/(m~3·d).(2)UASB reactor inoculated with conventional anaerobic granular sludge completed sludge acclimation after 47 days operation.The COD concentration of wastewater has large fluctuation(2540~5210 mg/L).COD removal rate maintained at 50%~60%and fluctuated strongly as volume loading rate was 7 kgCOD/(m~3·d).Another UASB reactor inoculated with conventional granular sludge and activated carbon completed sludge acclimation after 47 days operation.COD removal rate,which is better than the reactor only inoculated with conventional granular sludge,was over 60%with volume loading rate as 7 kgCOD/(m~3·d).The result showed that:compared with conventional granular sludge,PVA granular sludge had shorter sludge culture and acclimation period,higher removal rate and better stability.(3)The PVA granular sludge showed good settling performance with 120~130 m/h settling velocity.Through SEM,a large number of microorganisms aggregated on the PVA-gel beads.The VSS/TSS of conventional granular sludge decreased,particle size and settling characteristic were changed after operation.Adding activated carbon was helpful to improve the ability of resisting the change of water quality.It is favorable for maintenance of particle size and improvement of settling velocity.Through high throughput sequencing,the microbial community structure of granular sludge was studied.PVA granular sludge was rich in microbial species,the dominant microorganisms were Levilinea,Desulfovibrio,Syntrophorhabdus and Acetobacterium.Alpha diversity index showed that the microbial abundance and diversity of PVA granular sludge was higher than that of conventional granular sludge. |
