Abstract

As a common pretreatment process for coal chemical wastewater, the conventional one-stage coagulation process has the problem of poor removal of small size oil, which will inhibit the subsequent biological treatment. Measures to improve oil removal efficiency based on the development of new coagulants and the addition of composite processes are common in the literature, but two-stage coagulation to improve coagulation efficiency has not been reported to date. Here, we optimized coagulation parameters and compared the oil removal efficiency of two-stage coagulation and one-stage coagulation. Under the same total dosage of coagulant (PAC), the optimum removal of oil in two-stage coagulation was achieved 90% which increased by 11% compared to one-stage process. P10 and P 1 μm were proposed to evaluate the oil removing effect of two-stage coagulation. In addition, SEM scanning was used to conduct flocs analysis and two-stage coagulation process simulation, revealing the principle of the excellent oil removal performance of two-stage coagulation. Finally, coagulant in filter residue was recovered by acidification method and the recovered coagulant was used again in the two-stage coagulation process of coal chemical wastewater. These results suggest that two-stage coagulation is a cost-effective alternative oil removal technique with high energy efficiency and environmental benign. This research may offer helpful insights to develop an advanced oil removal process.

摘要

作为煤化工废水的常用预处理方法，常规的一级凝结工艺存在着难以去除小尺寸油的问题，这将抑制后续的生物处理。在文献中普遍采用基于新凝结剂的开发和添加复合工艺来提高除油效率的措施，但是迄今为止尚未报道过两阶段凝结以提高凝结效率的方法。在这里，我们优化了凝结参数，并比较了两阶段凝结和一阶段凝结的除油效率。在相同的总凝结剂（PAC）剂量下，两步凝结过程中油的最佳去除率达到90％，与一步过程相比提高了11％。建议使用P10和P 1μm来评估两阶段混凝的除油效果。此外，利用SEM扫描进行絮凝分析和两阶段混凝过程模拟，揭示了两阶段混凝具有优异的除油性能的原理。最后，通过酸化法回收滤渣中的凝结剂，并将回收的凝结剂再次用于煤化工废水的二级凝结过程。这些结果表明，两阶段混凝是一种经济高效的除油替代技术，具有较高的能源效率和环境友好性。这项研究可为开发先进的除油工艺提供有益的见解。通过酸化法回收滤渣中的混凝剂，并将回收的混凝剂再次用于煤化工废水的二级混凝工艺。这些结果表明，两阶段混凝是一种经济高效的除油替代技术，具有较高的能源效率和环境友好性。这项研究可为开发先进的除油工艺提供有益的见解。通过酸化法回收滤渣中的混凝剂，并将回收的混凝剂再次用于煤化工废水的二级混凝工艺。这些结果表明，两阶段混凝是一种经济高效的除油替代技术，具有较高的能源效率和环境友好性。这项研究可为开发先进的除油工艺提供有益的见解。