Application of an Electro-oxidation Treatment Method to Industrial Paper Mill Effluents in the Lab

電氧化法應用在工業用紙廠廢水之探討

彭元興(Yuan-Shing Perng) ； 王益真(I-Chen Wang) ； 余世宗(Shih-Tsung Yu) ； 林逸汎(Yi-Fang Lin)

《台灣林業科學》 23卷2期 (2008/06) Pp. 111-123

https://doi.org/10.7075/TJFS.200806.0111

摘要

造紙廠廢水經二級生物系統處理後，其水質指標已符合環保法規，但因電導度偏高(＞2000μs cm^(-1))及水色呈琥珀色，此將嚴重影響抄紙機濕端化學系統的穩定性及製程系統的潔浄度，導致處理後的廢水必須放流。本研究設計一套固定床電氧化反應器，以不銹綱棒為電極並以人造織維網包覆，以鐵珠為填充材料，填充量為反應槽容積的80~90%。實驗分成兩階段進行；第一階段為探討工業用紙廠原料（TOCC與EOCC）及化學藥品對於導電度的影響程度，第二階段為工業用紙典型廠經初級上浮處理的廢水直接泵入電化學反應器處理。以半批次式循環進行實驗。pH分別控制在3.0、6.8、9.0，反應時間(0~120 min)。電化學反應器的變數為停留時間(57、180s)、電極間距(5、15 min)及電流密度(287、3454 A m^(-2))。廢水評估指標為導電度、COD及色度。第一階段實驗結果顯示原料（TOCC及EOCC）對於導電度的影響不明顯，化學藥品中以硫酸鋁的頁獻度最高。第二階段電化學實驗結果顯示。在pH 6.8時，停留時間的增加會降低COD的去除效率。導電度去除率，各變數的影響皆不顯著。色度去除率停留時間與電極間距的增加會造成色度去除效降低。經電化學反應後的廢水利用循環伏安法(CV)來測試證實有Fe(上標 2+)/Fe(上標 3+)氧化還原對存在。在pH 3.0時，對於發水的污染負荷的處理沒有明顯的效應，會因鐵離子的增加導致導電度上升。在Ph 9.0時，COD去除率可達28%，真色色度去除率可以高達93.7%。電氧化反應器設計可以達到高電流密度的設計，但是對於汚染負荷的去除效率不彰，需要進一步再探討設計及參數設定。

關鍵字

電氧化法 ； 工業用紙廠廢水 ； 導電度 ； COD ； 真色色度 ； 循環伏安計

並列摘要

This study was conducted in 2 stages to examine the effects of effluent variables and reaction mechanisms on the treatment results of a typical industrial paper mill effluent by an electro-oxidation system. The first-stage study aimed mainly to analyze the contributions of raw materials, including old corrugated containerboard (OCC), from both domestic and imported European sources, and chemical additives, to the electric conductivity build-up of the effluents. In the second stage, the post-primary treatment (dissolved air flotation, OAF) effluent from an industrial paper mitt was treated in a lab-scale fixed-bed electro-oxidation reactor. The reactor contained 2 stainless steel electrode rods wrapped in permeable synthetic fiber membranes, and the cell was filled with iron beads to 80~95% of its volume. The effluent was recirculated in a semi-batchwise manner. The effluent pH was adjusted to 3.0, 6.8, and 9.0, respectively; and the reaction time was between 0 and 120 min. The reactor variables of the hydraulic retention time (HRT) (57 and 180s), electrode gap (5 and 15 mm), and electric current density (287 and 3454 Am^(-2)) were studied in a 2^3 factorial design. The effluent parameters investigated were the removal rates of electrical conductivity, chemical oxygen demand (COD), and true color. The results indicated that both domestic and imported OCC contributed little to the electrical conductivity build up of the effluent. Among the chemical additives, alum contributed the most to the conductivity build-up. As for the electro-oxidation treatment results, increasing the HRT caused a decrease in the COD at an effluent pH of 6.8. None of the variables examined showed a significant influence on electrical conductivity removal, however. Increasing the HRT and reducing the electrode gap caused the true color removal to decrease. The post-treatment effluent was analyzed using cyclic voltammetry (CV) for the presence of redox pairs, and the Fe(superscript 2+)/Fe(superscript 3+) redox pair was shown to exist. At pH 3.0, the treatment had no apparent efficacy, and increased release of ferric ion concentrations from the reactor medium led to an increase in electrical conductivity of the wastewater. At Ph 9.0, on the other hand, COD removal of 28% and true color removal of 93.7% were achieved. Our bench-top electro-oxidation reactor design could attain fairly high current densities; however, its pollutant removal efficacy was rather poor. Further remodeling and parameterization of the unit are necessary.

並列關鍵字

electro-oxidative method ； industrial paper mill effluent ； electrical conductivity ； COD ； true color ； cyclic voltammetry