Department of Civil and Environmental Engineering, Carleton University, 1125 Colonel By Drive, Ottawa, ON K1S 5B6, Canada.
Department of Civil and Environmental Engineering, Carleton University, 1125 Colonel By Drive, Ottawa, ON K1S 5B6, Canada.
J Environ Manage. 2018 Jun 15;216:406-420. doi: 10.1016/j.jenvman.2017.10.065. Epub 2017 Nov 20.
This study evaluated the ability of potassium ferrate(VI) and freeze-thaw to stabilise and dewater primary sludge. Potassium ferrate(VI) additions of 0.5 and 5.0 g/L were used as a pre-treatment prior to freeze-thaw. Samples were frozen at -10, -20 and -30 °C, and were kept frozen for 1, 8 and 15 days. The samples were subsequently thawed at room temperature in a setup which allowed meltwater to be separated from the sludge cake via gravity drainage. The meltwater was characterised in terms of fecal coliform, soluble chemical oxygen demand (COD), soluble proteins, soluble carbohydrates, pH and turbidity. The sludge cake was characterised in terms of fecal coliform, total solids (TS) and volatile solids (VS). Freeze-thaw with gravity meltwater drainage reduced the sludge volume by up to 79%. After being frozen for only 1 day, the concentrations of fecal coliform in many of the primary sludge samples were reduced to <1000 MPN/g dry solids (DS), representing >3-log inactivation in some cases. However, pre-treatment of the primary sludge with ≤5.0 g/L potassium ferrate(VI) resulted in significant increases in soluble proteins, soluble carbohydrates, and sCOD, and reduced the effectiveness of stand-alone freeze-thaw. Follow-up experiments using higher doses ranging from 5.1 to 24.9 g/L of potassium ferrate(VI) demonstrated that >5-log inactivation of fecal coliform in raw primary sludge can be achieved within 15 min using 15 g/L of potassium ferrate(VI), and the resulting concentration of fecal coliform in the sludge was 1023 MPN/g DS. Pre-treatment with 22.0 g/L of potassium ferrate(VI), followed by freeze-thaw, with only 3 days frozen, reduced the concentration of fecal coliform to below the detection limit in the meltwater and the sludge cake. This demonstrates that potassium ferrate(VI) and freeze-thaw offers the flexibility to adjust the ferrate(VI) dose to meet treatment requirements for land application, and can be used as a stand-alone sludge treatment technology for primary sludge that achieves both treatment and dewatering.
本研究评估了高铁酸钾（VI）和冻融稳定和脱水初沉污泥的能力。在冻融之前，使用 0.5 和 5.0 g/L 的高铁酸钾（VI）作为预处理。将样品在-10、-20 和-30°C 下冷冻，分别冷冻 1、8 和 15 天。随后，在允许通过重力排水将融化水与污泥饼分离的设置中在室温下解冻。根据粪大肠菌群、可溶化学需氧量（COD）、可溶蛋白质、可溶碳水化合物、pH 值和浊度对融化水进行了特征描述。根据粪大肠菌群、总固体（TS）和挥发性固体（VS）对污泥饼进行了特征描述。重力融化水排水的冻融使污泥体积减少了 79%。在仅冷冻 1 天后，许多初沉污泥样品中的粪大肠菌群浓度降低到<1000 MPN/g 干固体（DS），在某些情况下代表超过 3 个对数的失活。然而，用≤5.0 g/L 的高铁酸钾（VI）预处理初沉污泥会导致可溶蛋白质、可溶碳水化合物和 sCOD 的显著增加，并降低独立冻融的效果。使用从 5.1 到 24.9 g/L 的高铁酸钾（VI）的更高剂量进行的后续实验表明，在 15 分钟内可以用 15 g/L 的高铁酸钾（VI）使 raw 初沉污泥中的粪大肠菌群达到>5 个对数的失活，并且污泥中的粪大肠菌群浓度为 1023 MPN/g DS。用 22.0 g/L 的高铁酸钾（VI）预处理，然后进行冻融，仅冷冻 3 天，使融化水中和污泥饼中的粪大肠菌群浓度降至检测限以下。这表明，高铁酸钾（VI）和冻融为调整高铁酸钾（VI）剂量以满足土地应用的处理要求提供了灵活性，并且可以作为一种独立的初沉污泥处理技术，同时实现处理和脱水。
