固定床管柱實驗探討淨水污泥吸附含磷廢水之研究

Fix-bed column studies on the adsorption of phosphate containing wastewater by water treatment plant sludge

陳虹君(Hung-Chun Chen)

指導教授 ： 曾迪華

國立中央大學/工學院/環境工程研究所/碩士(2014年)

摘要

本研究以固定床管柱實驗操作方式，並利用淨水污泥為吸附材料，探討其去除水中磷酸鹽的可行性。實驗設計以平鎮淨水場之淨水污泥為吸附劑，並分別以人工配置含磷水樣及實際光電業含磷廢水為吸附質，探討吸附床高、初始磷濃度、流量及水樣pH值等不同操作因子，對吸附成效的影響，並驗證應用於實際光電業含磷廢水的可行性。此外本研究藉由床高-操作時間模式，探討吸附之動力學。至於吸附飽和後之淨水污泥，經SEM-EDS分析其特性，以確認污泥表面磷酸鹽的增量，有利於將污泥進一步作為土壤改良劑之再利用的目標。
實驗結果顯示，當增加吸附床高、減少初始磷濃度或進流流量時，管柱達貫穿濃度的操作時間可越長。由於本研究之淨水污泥的等電位點pH為2.82，故實驗結果發現，原水在pH = 2.5時之貫穿容量為其他pH值(pH = 3.5、4.0、7.0及9.0)之十倍至三十倍的變化範圍。在低pH時之貫穿容量明顯的提升，其主要機制是吸附劑表面的正電荷吸引水中負電荷磷酸根離子，並藉由配位基置換來吸附水溶液中的磷酸根。此結果也驗證淨水污泥對吸附光電製程之低pH高含磷濃度的鋁蝕刻清洗廢水，具有應用價值，且其BDST模式的吸附容量(N0)和速率常數(k)分別為409.20 mg/L 和0.002678 L/mg•min 。此外SEM-EDS之分析結果顯示，吸附飽和後之淨水污泥的表面結構，明顯與吸附前不同，且污泥表面磷成分百分比隨著貫穿吸附容量的增加而增加。

關鍵字

固定床管柱 ； 淨水污泥 ； 吸附 ； 含磷廢水 ； 床高-操作時間模式

並列摘要

The purpose of this study was to investigate the feasibility of adsorption of phosphate from wastewater by water treatment plant sludge (WTPS) as the material for the adsorption operation in a fixed bed column system. The experimental design employed sludge obtained from Ping-Jan water treatment plant as the adsorbent and the synthetic wastewater prepared in the Lab as well as the real wastewaters sampled from photoelectric industry containing phosphate were used as the adsorbate in this study. The effects of the various operation factors, included bed depth, initial phosphate concentration, flow rate and pH, on the performance of the column tests were investigated. Also, the feasibility of applying this technology to treat the real photoelectric wastewater containing phosphate was evaluated. In addition, the adsorption kinetic study was analyzed by the bed depth/service time (BDST) model. Meanwhile, as the sludge was exhausted by phosphate, the SEM-EDS analyses were carried to observe the surface change of the sludge structure and quantified the amount of phosphate adsorbed. The ultimate goal of this study is expected to further reutilize the exhausted sludge as soil conditioner.
The experimental results revealed that the increase of bed depth and the decrease of influent phosphate concentration and flow rate, the column breakthrough time were increased. Due to the pHzpc of the sludge was 2.82, the experimental results found that the breakthrough capacity of raw wastewater at pH = 2.5 was 10 to 30 times higher than those at the other pH (pH = 3.5, 4.0, 7.0 and 9.0). The fact of this phenomenon that the breakthrough capacity obviously increased at low pH was primarily due to the positive charge at the sludge particle surface adsorb the negative charge of phosphate ion in solution, and also by mean of the ligand-exchange mechanism. The results of pH effect in this study verified that WTPS is a well material with application value for the adsorption of low pH and high concentration of phosphate in Al-etching rinse wastewater from photoelectric industry. Moreover, the BDST model reveled that the adsorption capacity (N0) and adsorption rate constant (k) were 409.20 mg/L and 0.002678 L/mg•min, respectively, for Al-etching rinse wastewater. In addition, the results of SEM-EDS analysis showed the surface structure of sludge was significantly different before and after adsorption operation. The percentage of phosphorus composition on the surface of exhausted sludge also increased with the increase of breakthrough adsorption capacity.

並列關鍵字

Fix-bed column ； water treatment plant sludge ； adsorption ； phosphate containing wastewater ； BDST model

參考文獻

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