印刷電路板（Printed Circuit Board, PCB），在顯影去墨、剝膜製程所排出鹼性高濃度有機廢液具有高COD污染，以往的文獻與研究著重於COD去除效果，目前大多業者前處理採酸化處理居多，雖然具有簡單快速等優點，但並未突顯因酸化逆反應造成墨渣黏滯，使處理設備損壞與固化造成管路槽體結垢等，常常衍生出不可預期之問題，影響前處理的穩定性。 本研究目的是為了解決墨渣黏滯與固化問題，選擇以鋁鹽與鐵鹽兩種不同混凝劑，以直接添加於廢液在進行pH值調整，藉由混凝劑特性與混凝機制不同，改變酸化逆反應所造成的問題，將混凝劑濃度、pH值、化學與物理影響與酸化處理作一比較，找出最佳前處理模式與方法，以供未來新設或改善處理此廢液參考。 研究結果顯示，直接以鋁鹽PAC於前處理添加，混凝劑具高價陽離子及架橋能力強等特性，可取代酸化逆反應形成墨渣影響，以電性中和吸附作用機制為主，能改變墨渣凝聚造成黏滯與固化等問題，PAC濃度越高效果越好，而FeCl3則無法改變酸化逆反應影響。當加入PAC 3000mg/L，在pH值5至6可造成沉澱絆除作用，NTU可降至14至18，沉澱絆除可以作為調整加藥的指標，而最佳前處理模式為，以PAC進行化學混凝，將固液分離在接續後續處理。FeCl3混凝與酸化處理，因黏滯與固化等問題無法有效解決則不建議採用。 ;In the Printed-Circuit-Board (PCB) industry, the Develop-etch-strip (DES) process would produce high-polluted alkaline wastewater with high concentration of organic substances. In the past, diluting wastewater by acidification treatment has been utilized widely; however, the ink residue caused by acidification treatment would solidify and damage the equipment or block the piping lines. It influences the stability of pretreatment water and sometimes leads to unpredictable problem as well. The present study aims to solve the ink residue issue by adding coagulant like aluminous and ferric contained salt and adding acid to control pH of wastewater. In other words, this study tried to solve the problem caused by the acidification reaction according the characteristics of coagulant and the different coagulation mechanism. The experiment compared the physical and chemical influence by adding different level of acid and different amount of coagulant, and then tried to find out best treatment model/formula which can be applied by newly-installed equipment of pre-treatment process. The result showed that by adding aluminous salt (PAC) in the pretreatment process could neutralize wastewater and could also replace the acidification reaction which led to the formation of ink residues since the PAC coagulant is a high-valence cation and can avoid the formation of ink residue via the electron-charged adsorption mechanism. It is found that the higher concentration of PAC and the more obvious mitigation of ink residue. On the other hand, the FeCl3 cannot change the impact of acidification. At pH of 5 to 6, the addition of PAC of 3000mg / L could lead to co-precipitation of high concentration of organic substances and coagulant. Meanwhile, the Nephelometric Turbidity Unit (NTU) can be reduced from 1032~1482 to 14-18. The phenomena of co-precipitation can be an index of adjustment of dosing. On the base of above results, the best model can be concluded as by adding PAC to the pre-treatment wastewater and fixed under weak acid condition, waiting for occurrence of solid-liquid separation and then follows the subsequent processing.
