粉末活性炭对电控反冲浸没式膜—生物反应器处理中药废水的影响

Influence of powdered activated carbon on Chinese traditional medicine wastewater treatment in submerged membrane bioreactor with eletronic control backwashing

采用2套完全相同且平行运行的电控反冲浸没式膜—生物反应器(SMBR)处理富含甙类等易发泡而难降解的大分子物质的中药废水。其中一套SMBR放入粉末活性碳(PAC)(即PSMBR),另一套不放(即CSMBR)。反冲时间为5min。通过调整预设反冲真空度及泵频使得抽吸周期约为90 min。在24 d(576 h)平均水力停留时间(HRT)为5.97 h的稳定状态内,CSMBR平均流量为5.87 L/h;而在30 d(720 h)平均HRT为5.99h的稳定状态内,PSMBR平均流量为5.85L/h。平均有机负荷(OLR)为4.16 kg COD/(m3.d)时,CSMBR化学需氧量(COD)平均总去除率为89.29%,而平均OLR为5.50 kgCOD/(m3.d)时,PSMBR的COD平均总去除率为89.79%。2套SMBR出水COD质量浓度均达GB 8978—1996《污水综合排放标准》医药原料药工业污水二级排放标准(300 mg/L)。因此电控反冲SMBR处理中等质量浓度的中药废水是可行的。再者,PSMBR的电接点真空压力表的预设反冲真空度、泵频、以及混合液真空度和流量损失均滞后于CSMBR,故PSMBR不进行膜清洗的实际运行时间约为CSMBR的1.25倍,且当平均OLR较高时,PSMBR的COD平均总去除率增强。

Chinese traditional medicine wastewater,which was rich in macromolecule difficult to be treated and easy to foam in aerobic biodegradation,such as Glycosides,was treated by two identical bench-scale aerobic submerged membrane bioreactors（SMBRs） operated in parallel under the same feed,equipped with same eletronic control backwashing device.One SMBR was used as the control（control SMBR,CSMBR） whilst the other was dosed with powdered activated carbon（PAC）（PAC-amended SMBR,PSMBR）.The backwashinginterval was 5 min.One suction period was about 90 min by adjusting preestablished backwashing vacuum and pump frequency.The average flux of CSMBR during a steady periodic state of 24 d（576 h） was 5.87 L/h with average HRT of 5.97 h and that of PSMBR during a steady periodic state of 30 d（720 h） was 5.85 L/h with average HRT of 5.99 h.The average total Chemical oxygen demand（COD） removal efficiency of CSMBR was 89.29% with average organic loading rate（OLR） at 4.16 kgCOD/（m3·d） while that of PSMBR was 89.79% with average OLR at 5.50 kgCOD/（m3·d）.COD concentration in effluent of both SMBRs achieved the second level of the general wastewater effluent standard GB8978-1996 for the raw medicine material industry（300 mg/L）.Hence,SMBR with eletronic control backwashing was a viable process for medium strength Chinese traditional medicine wastewater treatment.Moreover,the increasing rates of preestablished backwashing vacuum,pump frequency and vacuum and flux loss caused by mixed liquor in PSMBR were all lagged compared to those in CSMBR;thus the actual operating time of the PSMBR system without membrane cleaning was extended by up to 1.25 times in contrast with the CSMBR system,and the average total COD removal efficiency of PSMBR was enhanced with higher average OLR.