以多元氯化鋁處理高化學需氧量廢水之可行性評估

Feasibility of Treating High Chemical Oxygen Demand Wastewater Using Polyalumino-chloride

蔡俊男(TSAI-CHUN-NAN)

指導教授 ： 黃武章

國立屏東科技大學/工學院/環境工程與科學系所/碩士(2013年)

https://doi.org/10.6346/NPUST.2013.00226

摘要

石化工業是一個國家的民生基礎工業，早期國內在石化工業廢水處理設計上常用之混凝劑為氯化鐵，但是氯化鐵會有管路銹蝕與堵塞的問題。現在國內則多改用多元氯化鋁 (Polyaluminum chlorine, PAC)。本研究是針對南部某化工樹脂業生產過程產生之高化學需氧量（Chemical Oxygen Demand, COD）廢水處理廠，進行使用PAC及氯化鐵當混凝劑之差異比較。本研究取水樣測試經稀釋2~4倍的PAC液的混凝性。瓶杯試驗相關設定條件為快混3分鐘（150 rpm），慢混20分鐘（30 rpm）之後靜置30分鐘後記錄膠羽厚度取上層液測試濁度及COD值。
以上述條件先測試其最佳pH值，結果稀釋2倍及4倍其最佳pH值為3，之後進行最佳添加量測試，稀釋2倍及4倍其最佳添加量均為8 mL/L；換算回未稀釋劑量分別為4 mL/L及2 mL/L。由於使用鐵劑當混凝劑須添加高分子助凝劑（1000:1稀釋，添加量為10 mL/L）加速其膠凝作用，測試添加陽/陰離子型高分子助凝劑後混凝效果，結果顯示添加與不添加的COD移除率均相同；但未添加高分子助凝劑有較好的濁度。膠羽為下層的沉澱物，測試膠羽是否可被濾紙過濾，主要是評估下層液後續處理問題，結果顯示沉澱後的膠羽可被過濾，且過濾後液體為澄清透明。最後測試不同批次PAC之混凝能力。觀察瓶杯試驗下之COD、膠羽厚度、濁度與初始pH值的關連。結果顯示不同批次的PAC之COD移除率為91.5%及88.3%，有其再現性。
數據顯示經稀釋後的PAC有較佳的混凝效果，且可以不用添加高分子助凝劑（使用氯化鐵當混凝劑時須添加）。稀釋2~4倍之PAC 經瓶杯試驗後，在pH=3.0的操作條件下有較佳的COD移除能力、膠羽厚度及最低濁度。本研究證實經稀釋後PAC的確在廢水混凝上有其果效，可用於此類石化工業廢水處理中。

關鍵字：化學需氧量、廢水處理、瓶杯試驗、膠羽、混凝、最佳pH、最佳添加量。

關鍵字

化學需氧量 ； 廢水處理 ； 瓶杯試驗 ； 膠羽 ； 混凝 ； 最佳pH ； 最佳添加量

並列摘要

Petroleum industry is a fundamental public industrial for a country. In the past iron chloride is usually used as the coagulant for such kind of wastewater. However the corrosion and blocking of pipe is serious in the use of iron chloride, currently Polyaluminum chlorine (PAC) is more popular for using as coagulant. The study had focused on the used chemical sedimentation tank to explore the chemical oxygen demand (COD) removal rate, reproducibility, and the best operating conditions in a industrial resin manufacturing plant for treating their produced high COD wastewater.
In the experiment, we tested the coagulation of 2 to 4-fold PAC for high COD resin wastewater that produced by the chemical process from a chemical factory of Southern Taiwan. The relations between COD, the thickness of the floc turbidity, and initial pH value in jar test were discussed in the study. Jar test set conditions related to rapid mixing 3 minutes (150 rpm), slow mixing 20 minutes (30 rpm) for 30 minutes after recorded the thickness of the upper liquid flocculating test turbidity and COD values.
In these conditions the optimum pH value of the first test, the result was diluted 2-fold and 4-fold its optimum pH 3, after the optimal dosage tested diluted 2-fold and 4-fold the optimum amount were 8 mL / L; translated back No amount of diluent were 4 mL / L and 2 mL / L. The use of iron to be added when the coagulant polymer coagulant (1000:1 diluted dosage of 10 mL / L) to accelerate its gelation test add male / anionic polymer coagulant coagulation effect after the results showed that adding with and without added COD removal rate of the same; but added polymer coagulant better turbidity. Floc precipitate is lower, the test is whether Floc filter paper, mainly the lower liquid evaluate subsequent processing, and the result shows flocs can be precipitated is filtered, and the filtered liquid is a clear and transparent. Final testing of different batches of PAC coagulation capability. Jar test under observation COD, floc thickness, turbidity and the initial pH value connected. The results show the different batches of PAC COD removal was 91.5% and 88.3%, has its reproducibility
The results show that the diluted PAC has a better coagulation efficiency without the addition of polymer coagulant additives (use the iron when the coagulant must add). The 2 to 4-fold diluted PAC whit a pH = 3.0 in the jar test have show a better COD removal capacity, the thickness of the floc, and lowest turbidity. This study demonstrates that the diluted PAC has better coagulation efficiency for the tested wastewater. This method could be applied to the same kind of industrial wastewater treatment.

Keywords: COD, wastewater treatment, jar test, floc coagulation, optimal pH, optimal added amount.

並列關鍵字

COD ； wastewater treatment ； jar test ； floc coagulation ； optimal pH ； optimal added amount ； HASH(0xef06250)

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