應用固定化微生物處理煉焦程序之二級排放水

Abstract

為提高整廠的處理效率並降低成本，本研究以固定化微生物Entrapped Mixed Microbial Cell (EMMC) 反應槽處理煉焦程序經二級處理後之排放水，並探討水力停留時間 (hydraulic retention time，HRT) 及顆粒填充率 (packing ratio) 對處理效率的影響。 實驗全程溫度控制在30±1℃，以24 hrs HRT進行起動馴化實驗，待穩定後再以不同HRT (12、8、6、4、2及1 hrs) 和不同顆粒填充率 (35%和20%) 為操作條件觀察EMMC之處理效率；另外以污泥 (VC-756) 直接處理廢水 (VC-757)，測試生物降解能力。並且在減少HRT、去除率持續下降的試驗後，將進流改為高濃度的原廢水 (VC-703) 對EMMC進行活性恢復實驗。 結果顯示，EMMC在顆粒填充率35%、HRT 12 hrs的操作條件下，有最高的SCOD去除率23%；在填充率35%、HRT 8 hrs時有最高的TSS去除率93%，而填充率20%、HRT 8 hrs時有最高的TCOD去除率52%。此外，有機負荷在63 mg TCOD/L/hr時 (HRT 8 hrs)，系統的TCOD去除率可達50%以上，而有機負荷在24 mg SCOD/L/hr 時 (HRT 12 hrs)，SCOD去除率亦可超過20%。至於生物降解能力的實驗，以污泥VC-756和廢水VC-757依4:1的比例混合處理12天後，SCOD最低可以降至479 mg/L，由此推算VC-756的生物可消化程度約為18%。在EMMC處理效率逐漸下降時，以1:1比例混合原廢水VC-703和二級排放水VC-757做為進流，其TCOD去除率提高至68%，SCOD去除率則可提高達73%，並估算出EMMC對VC-757的SCOD理論去除率 (theoretical removal efficiency，TRE) 可達78%。

In order to improve the performance of the treatment plant and reduce its operating cost, the Entrapped Mixed Microbial Cell (EMMC) reactors were utilized to treat the secondary effluent of the coking process in this study. The effects of the hydraulic retention time (HRT) and the packing ratio on the treatment efficiency were evaluated. Temperature was controlled at 30±1°C during the whole experiment. Operation of the EMMC reactors were started with an HRT of 24 hrs, and followed with 12, 8, 6, 4, 2 and 1 hrs of HRT’s. Two different packing ratios, 35% and 20%, were also tested to assess the efficiency of the EMMC reactors. Also, the biodegradability of the secondary effluent VC-757 was examined using the activated sludge (VC-756). Besides, reactivation of the EMMC was conducted after series of reducing HRT tests. The concentrated raw wastewater (VC-703) was used as feed in the reactivation experiment. Results showed that, at the operational condition of 35% packing ratio and 12 hrs HRT, the optimal SCOD removal efficiency of 23% was achieved. The highest TCOD removal efficiency of 52% was achieved at 20% packing ratio and 8 hrs HRT, while the highest TCOD removal efficiency of 93% was observed at 35% packing ratio and 8 hrs HRT. Additionally, when comparing the organic loading, more than 50% of TCOD removal efficiency could be achieved at 63 mg TCOD/L/hr (at the test of HRT 8hrs), and more than 20% of SCOD removal efficiency was observed at organic loading of 24 mg SCOD/L/hr (HRT 12 hrs). For the biodegradability test of the feed VC-757, after 12 day’s treatment with 4:1 mixture of activated sludge (VC-756) and VC-757, SCOD was observed at the lowest concentration of 479 mg/L. Therefore, the biodegradability of the feed (VC-757) was estimated about 18%. In the reactivation test, after feeding with 1:1 of raw wastewater VC-703 and the secondary effluent VC-757, the TCOD removal efficiency was remarkably improved to 68%, and the SCOD removal efficiency was improved to 73%. Accordingly, 78% of the theoretical SCOD removal efficiency could be estimated for treatment of VC-757 using EMMC.