純氧活性污泥法具有節省曝氣槽用地的優點，中壢工業區污水廠擴建工程即採用此系統，然試運轉期間卻發現處理效果不如預期。基於以上理由，本研究以中壢工業區污水廠之綜合性工業廢水為處理對象，建立純氧活性污泥法之模型廠，探討原廢水水質特性及純氧活性污泥法之操作條件，對微生物活性及處理效率的影響；此外，添加粉末活性碳(PAC)於曝氣槽內，成為PAC/O2活性污泥系統，探討提高生物活性，提升污染物去除率之可行性。而根據實驗結果顯示，原廢水之生物可分解性COD濃度佔總COD濃度之77﹪，推測生物處理效果極限應無法超過77﹪。在水質特性方面，當BOD5/CODt比值增加，將有助於提高微生物活性。廢水出流水中的溶解性重金屬濃度與迴流污泥中之重金屬，有影響微生物活性的情況。在操作條件對微生物活性的影響方面，當水力停留時間越短，廢水進流量越高，微生物之SOUR越高。而微生物活性SOUR對BOD5去除率的影響不大，主要是影響CODs去除率，微生物活性越高，CODs去除效果越佳。實驗中發現，當BOD5/CODt比值為0.20∼0.25，F/M比控制在0.25∼1.10mg CODt/mg VSS/day時，CODt去除率最高為70﹪，CODt殘留濃度最低為200mg/L左右，生物處理系統已達處理極限。在PAC/O2活性污泥系統操作方面，PAC的添加對BOD5的去除率幫助不大，但對DOC及CODs去除率，則有明顯的提升。此外，PAC的添加並未提高SOUR，因此認為PAC並不影響生物活性。根據以上研究結果，本研究認為，為避免迴流污泥中重金屬的累積，影響微生物活性與COD去除率，迴流污泥中重金屬濃度應予以限制。除了加強進廠管制以外，應從水力停留時間及污泥濃度著手，嚴格控制F/M比與濃度時間乘積，避免重金屬累積對操作效率造成影響。 A wastewater treatment plant with pure oxygen activated sludge process for treating agro-industrial wastewater was constructed in Chungli Industrial Park. Since the treatment efficiency of new system did not meet the design, a pilot plant of pure oxygen activated sludge process was constructed and the factors affect performance were evaluated. The industrial wastewater characteristics and operation condition were determined in this study. For further enhancement of COD removal, the PAC/O2 activated sludge system by adding powdered activated carbon(PAC) into aeration tank was also evaluated. According to the COD fraction analysis of raw wastewater, the biodegradable COD fraction was found about 77﹪of total COD. For this reason, the biological COD removal was expected below 77%. When the BOD5/CODt ratio of raw wastewater increased, the activity of biomass also increased. The soluble metal in the effluent and the total metal in the return sludge was found reduce biomass activity. When the hydraulic retention time(HRT) was shortened, the specific oxygen uptake rate(SOUR) of biomass increased. The SOUR was found an important factor for the removal of soluble COD. When the SOUR increased, the removal of soluble COD increased. The maximum removal of total COD is about 70﹪ and the residual total COD is about 200 mg/L, where the BOD5/CODt ratio is between 0.20 and 0.25, and the F/M ratio is between 0.25 and 1.10 mg CODt/mg VSS/day. The result implies the ultimate COD removal of biological treatment has been reached. In the PAC/O2 system, the addition of PAC improved the removal of dissolved organic carbon(DOC) and soluble COD. However, the BOD removal was not improved. The biomass activity was not affected by PAC. Therefore the SOUR was maintained before and after the addition of PAC. In summary, this result showed that the biomass activity and COD removal were mostly affected by the heavy metal concentration in return sludge. Thus the F/M ratio should been controled by adjusting HRT and sludge concentration to avoid significant accumulation of heavy metal in biomass.
