利用生物薄膜反應器處理高科技園區廢水生物毒性之研究

Abstract

高科技產業三十年前經由政府扶植在竹科設立，隨著世界之趨勢蓬勃發展，帶動國內經濟起飛提升生活品質的同時，所衍生的環境問題也逐漸被國人重視。國內高科技產業發展以積體電路及光電產業為主，製程中需要使用大量水資源，屬於高耗水性產業；然近年各地紛紛仿效竹科成功經驗規劃設立高科技產業密集設立之科學園區，用水的來源及產生之工業廢水去處便成為各方關注之焦點。環保署有鑑於高科技產業使用眾多新興化學品，事業單位排放之放流水雖符合公告之放流水標準，但部分放流水仍存在微量毒性物質，造成對水體生物之影響，故民國99年將科學園區放流水生物急毒性列入放流水標準中；而101年時因增訂「科學工業園區污水下水道系統放流水標準」將科學園區放流水單獨列管，故將生物急毒性改列入定期檢測申報管理辦法中。爰此，放流水管制不再只局限於單項水質項目，而可由生物指標確實管制放流水對水體生物之影響，維護良善水體水質。 本研究乃針對高科技園區廢水以缺氧/好氧生物薄膜反應器(A/O MBR)模廠處理後進出流水生物急毒性之影響，以及高科技園區污水處理廠既有處理設施進放流水之生物急毒性變化進行探討，並比對高科技園區既有污水處理廠及MBR模廠出流水各項水質與生物急毒性之關聯性。 MBR模廠設置於高科技園區污水處理廠內，取經過前處理後之廢水進入模廠，實驗結果顯示SS平均去除率約96%，BOD5平均去除率約90.1%，TN平均去除效率約48%，NH4+-N平均去除效率約75%，出流水TN平均為40mg/L，NH4+-N平均為13.9mg/L；模廠進流水對水蚤(Daphnia)之生物急毒性TUa均大於5具急毒性，而出流水TUa均小於1，顯示外加碳源之MBR模廠可有效降低高科技廢污水之生物急毒性。以高科技園區污水處理廠進放流水各項水質與生物急毒性進行多變數線性回歸，所得之方程式R2及adj-R2分別為95.1%及87.8%，其中As、Cu、Nitrate、Ammonia與TN對生物急毒性有影響；另比對研究期間污水處理廠放流水及實驗模廠出流水同日水樣各項水質與生物急毒性之關聯性，發現SS、BOD5、As、TN、Ammonia及TMAH為影響污水處理廠放流水生物急毒性之主要因子。

High-tech industry was supported and established in Hsinchu by government thirty years ago, and also expanded with the trend of the world. However, when high-tech industry led economy take-off and made better quality of life, environmental issues gradually emphasized by the people. The development of high-tech industry including integrated circuit and optoelectronic industries require a lot of water during manufacturing process. In recent years, many cities followed the successful experience of the Hsinchu Science Park, planning to set up Science Park. The water resource and wastewater generated from producing processes have become an important issue of concern. Although the effluent of factory comply with the national effluent standard, EPA still pay attention to the toxic effluence to aquatic organisms due to the high-tech industry using many emerging chemicals. Therefore, EPA legislated Science Park sewer system effluent standard for biological acute toxicity in 2012. The regulation of effluent not only limited to single water quality item but also supervised by biological indicators. The biological acute toxicity of influent and effluent between a pilot-scale anoxic-oxic membrane bioreactor (A/O MBR) with addition of carbon source and wastewater treatment plant in high-tech Science Park was investigated, and also finding out the relevance of biological acute toxicity with the item of water quality. The pilot-scale MBR system was set up at wastewater treatment plant in high-tech Science Park and the pretreated wastewater was pumped into MBR system. The experiment results revealed that the average concentrations of TN and NH4+-N were 40 mg/L and 13.9 mg/L. And average removal efficiency of TN and NH4+-N and SS BOD5 reached about 48% and 75% and 96% and 90.1%, respectively. The Acute Toxic Unit (TUa) of MBR’s influent for Daphnia magna were all above 5, however TUa of effluent were less than 1. It means the treatment of high-tech wastewater using MBR process with addition of carbon source could effectively reduce the acute toxicity of wastewater. Use of multivariate linear regression to compare the relationship of water quality items and biological acute toxicity in influent and effluent between the pilot-scale MBR system and wastewater treatment plant, the R2 and adj-R2 of equation were 95.1% and 87.8%, and the water quality items such as As, Cu, Nitrate, Ammonia, and TN were found to be the main factors to affect the acute toxicity of effluent. Another compared the relationship of water quality items and biological acute toxicity in the same day effluent between the pilot-scale MBR system and wastewater treatment plant, SS, BOD5, As, TN, Ammonia, and TMAH were found to be the main factors to affect the acute toxicity of effluent.