| 摘要: | 本研究主要討論應用冷凍融化法於廢水之處理並探討化學調理劑對廢水污泥物性與化性之研究。廢水凍結分離法主要將廢水中之污泥與水冷凍處理後達到固液兩相分離，其中上層澄清液之化學需氧量(COD)、生化需氧量(BOD)與懸浮固體量(SS)可達到廢水排放與再循環利用之標準，而污泥層中之膠羽凝聚團顆粒變大且較緊密，沉降性亦大幅改善，處理完成之污泥餅含水率可大幅降低，以降低污泥處理體積。
廢水凍離法之主要操作參數包括冷凍溫度、冷凍速率、冷凍時間、化學調裡劑種類及汙泥濃度等。經冷凍處理後之的廢水污泥之各項排放水性質測試則包括總體固體含量(TS)、懸浮固體含量(SS)、毛細汲取時間(CST)。此外亦於實驗中以熱式差掃描卡計(DSC)對廢水做其相圖之測量。研究成果希望能使具有廢冷之工廠回收其廢冷再應用於其工廠產生之廢水做凍結分離處理，可使工廠達到能源之再利用及省能之效果，並建立完成廢水凍結融化分離法之最適化處理程序。
本研究中採用染整廠之污泥及新竹工業區綜合廢水處理廠的二次迥流生物污泥，以-10℃的恆溫處理以及-10℃~-15℃的變溫處理，凍結速率平均可達8mm/hr。另在不同污泥濃度下加入不同濃度之化學調理劑，在冷凍溫度-10℃下凍結24小時並在其溶解後，測定其廢水污泥之物性與化性。由結果分析得知，以硫酸鋁及陽離子性與陰離子性聚丙烯醯肢來調理汙泥，發現採用硫酸鋁及陽離子性高分子能夠改善污泥之脫水性。經過凍融法及化學調理劑雙重調理後的污泥，其污泥脫水性最好可以達到70%以上，且其COD去除率可以達到80%以上；以二次冷凍技術處理染整廢水，並以DSC測試廢水樣品，發現經過凍融處理後的廢水，其性質接近於純水顯示廢水凍結分離與調理劑之雙處理，確實可以改善廢水及污泥之特性。
In this study, the wastewater was treated by the freeze/thaw technology. The performances of the treated wastewater were experimentally investigated. When the wastewater sludge freezes, both the suspended and dissolved solids were rejected by the growing ice front, and certain sludge dewatering characteristics were significantly improved. The floe structure was changed into a more compact form, and the bound water content of the sludge was also reduced.
The experimental and operational parameters, which are freezing temperature and time, curing time, chemicals, concentration of sludge, stirring, rheogram and the additive of seed ice were used. The physical and chemical performances of the treated sludge and wastewater, such as COD, TS, SS, CST and filterability were experimentally tested in order to get the optimum operation conditions. Furthermore, the DSC were also used to measure the DSC thermograms.
Model wastewater and two types of actual wastewater from dyeing industry and Hsinchu wastewater station were used. Under the various freezing temperature range from -5℃~-20℃ conditions, the maximum average freezing speed is about 8mmlhr. The dewaterability and the reduced COD level of the wastewater treated by using the A12 (SO4)3 and cationic Poly Acryl Amide additives are reached to 70% and 80%, respectively. The settling velocity of the treated sludge also increased due to the floe aggregation by freezing. The treated wastewater meets the water pollution control regulation in Taiwan. We expect the freeze/thaw technology will be applied on the factory which has the waste cold energy, which can be recycled to be used to treating the wastewater and increasing the energy efficiency. |
