利用電聚浮除輔助固定式生物程序處理底渣廢水之研究

Abstract

電聚浮除因具不用添加額外藥物的條件下，可有效處理廢水中之SS、重金屬物質與難分解有機物的優點，因此於應用上已漸漸取代傳統混凝膠凝。由於電聚浮除對COD之去除率較生物反應系統低，且固定式生物槽之進流水SS負荷不能太高，因此若以電聚浮除結合固定式生物處理，不僅可降低固定式生物槽對SS之負荷，亦可進一步降低COD之出流水濃度。因此本實驗為以電聚浮除作為固定式生物之前處理程序，對底渣廢水之研究討論。 實驗結果顯示，以電聚浮除作為固定式生物之前處理(於電聚浮除之操作條件為電壓200 V、流量500 mL/min，固定式生物之操作條件為12 小時HRT且連續式曝氣)，電聚浮除可有效降低廢水SS濃度(初始濃度SS：550 mg/L；電聚浮除出流濃度SS：14.4 mg/L)，再經固定式生物程序之出流水濃度為SS：8.4 mg/L、COD：94 mg/L、Cu：0.151 mg/L。另一方面，以陰、陽離子聚凝劑作為固定式生物之前處理與電聚浮除作比較。實驗結果顯示，此三種前處理程序對SS之去除率皆90%以上，其中以陽離子聚凝劑去除效果最佳(99.14%)，電聚浮除作為固定式生物前處理程序對重金屬物質(銅)處理效果較好(初始濃度：1.705 mg/L；出流水：0.151 mg/L)。 以電聚浮除作為固定式生物之前處理程序確實能有效降低進流水之SS濃度且提高COD與重金屬之處理效果。此電聚浮除之最佳操作條件為電壓2OO V與流量500 mL/min，於此實驗範圍內，操作電壓與流量愈大則電聚浮除之處理效果較好，進流水之pH愈高則COD、SS、銅之去除率相對較高，導電度不影響廢水之處理效果。

Fixed Carrier Biological System in a single-pass process with long sludge retention time (SRT) and low solids production rate was developed and tested to achieve simultaneous removals of organic carbon and ammonia nitrogen with the assisting of electro-coagulation. This is because electro-coagulation (EC) has become an alternative application to replace chemical coagulation and effectively applied in industrial wastewater treatment because of EC can remove the suspended and colloidal solids, heavy metals and refractory substances in the wastewater. The influent of bottom ash wastewater consists 450-550 mg/L of SS, 370-420 mg/L of COD, 1.701-1.711 mg/L of heavy metals. The EC was compared with another two types of pretreatment methods, anion and cation polymers as pretreatment for FCBS. Under the experimental conditions, all the pretreatment methods able to remove up to 90% suspended solids, but anion and cation polymers were not effectively in removing the COD and heavy metals. The EC with optimum operating parameters (voltage-200 V, flow-500 mL/min) as the pre-treatment of the FCBS could remove 535 mg/L (97.3%) SS, 59 mg/L of COD (15.5%), 1.491 mg/L of heavy metals (87.44%). The effluent of EC was being fed to FCBS, and to help FCBS achieved excellent performance removal rate of SS (98.47%), COD (75.26%)and heavy metals (91.15%). Therefore, EC was selected as a better pretreatment consideration as compared with other pretreatment methods for FCBS in order to remove SS and heavy metals (copper) effectively. Further, it was found that the conductivity in the wastewater does not affect the removal rate for EC and the higher the voltage and the flow in the electro-coagulation, the higher the removal efficiency of the SS、COD、Cu and the pH is.