本研究針對金屬表面處理業(○○工業)製程內所排放的高濃度廢硫酸酸洗液之處理及資源化，本研究先調查該公司的原物料製程，了解廢水處理流程，及廢水各項單元操作的參數，並針對實驗對象槽體以低溫、改變pH值、蒸發的方式來回收廢酸中結晶的硫酸亞鐵、藉此來降低廢水處理中產出的汙泥量且降低水中TDS由研究所得改善前與改善後的污泥排放量及評估改善措施對於污泥清運費及加藥量的成本節省效益。
實驗過程中於廢酸暫存槽中採樣了1 L的廢硫酸，鐵離子濃度為43,025 mg/L、TDS為41,200 mg/L溫度為攝氏70度，採樣後降溫為常溫，接著冷凍至?5度，發現採樣瓶底部產生翠綠色的結晶物，重量約為250 g依據Eh-pH圖是根據溶液的氧化還原電位去判斷此結晶鹽類為七水硫酸亞鐵，為求得更有效率的結晶量， pH 4樣本實驗取得一水硫酸亞鐵為303 g，pH 2樣本實驗取得結晶量為235 g，評估○○工業廢水處理廠及製程實場評估後估算廢水中鐵離子轉化為Fe(OH)3金屬固體物之污泥量，改善結果，污泥減量了270.1 kg，TDS經廢水處理程序後降為325 mg/L，估算各項成本得出改善結論是以取出廢酸中的鐵鹽結晶回收，對該工業水污染防治計畫來說，是可行且能節省成本的。 The purpose of this study was focused on developing a new reused method for waste sulfuric effluent from metal surface cleaning process of XXXX industrial Co. After identify and analyzing waste effluent compounds, the modification of wastewater treatment process and optimization operating parameters of wastewater treatment process had made by cooling process, changing pH, vaporization and crystallization to recovering sulfuric iron from the effluent. It was found that above medications method effective decreased the chemical sludge and total dissolved solids (TDS) in the effluent. The cost down of the modification of the wastewater treatment process were also discussed in this investigation.
In this study, the discharge waste acid contained iron concentration up to 43025 mg/L and 41200 mg/L TDS at 70℃. At low temperature operating condition, the solution crystallization green crystal was found and 303g iron sulfate was obtained with 1 liter waste under the best operating condition. It is possible to decrease 270 Kg/day iron waste from the process. It can be also concluded that recovery iron sulfate from the effluent waste is the best option to reduce the waste and improve the effluent wastewater quality and effectively cost down the treatment process.
