废塑料再生过程废水中微塑料去除模拟试验

微塑料是一种存在于不同环境介质中的新兴污染物，主要来源于废弃塑料制品，其存在污染范围广、潜在环境污染大的问题.废塑料再生企业生产废水中微塑料浓度远高于其他类型废水，对其生产废水中的微塑料进行处理具有重要的环境意义.模拟废塑料再生过程的生产废水并进行微塑料去除的絮凝沉淀试验，研究絮凝剂投加量、pH、水力快速搅拌条件的单因素和正交试验对废水中微塑料去除率及其各因素作用的影响.结果表明:①当PAC (聚合氯化铝)投加量为10 mL，PAM (聚丙烯酰胺)投加量为7 mL，pH为9，水力快速搅拌条件为100 r/min下维持40 s再200 r/min下维持40 s时，微塑料的总去除率最高，达91%.②PAC投加量是影响微塑料去除效果的主要因素，其次是pH.③微塑料的去除率与其本身的密度有关，密度大的ABS (acrylonitrile butadiene styrene，丙烯腈-丁二烯-苯乙烯)去除率最高，密度小的PE (polyethylene，聚乙烯)去除率最低.④不同粒径区间的微塑料去除率区别较大，粒径小(0.1~0.25 mm)的微塑料去除效果最好.研究显示，通过控制PAC和PAM的投加量、pH和水力搅拌速率等条件，能够有效将废水中的微塑料通过絮凝沉淀的方法去除，从而达到净化含微塑料生产废水的目的. 

Simulation Experiment of Microplastics Removal in Waste Plastic Regeneration Effluent

Microplastics are emerging pollutants that can be founded in different environments. Microplastics mainly come from waste plastic products, they have a wide range of pollution and potential environmental pollution problems. The concentration of microplastics in wastewater from waste plastic recycling enterprises is much higher than that of other types of sewage. Hence, it is of great environmental significance to treat microplastics in the wastewater of waste plastics recycling enterprises. By simulating the production of wastewater from waste plastics recycling enterprises and flocculation precipitation, this study explored the influence of several factors that affect the removal rate of microplastics in wastewater including flocculant dosage, pH value, hydraulic stirring single factor and orthogonal experiment. The results showed that: (1) When the dosage of PAC was 10 mL, PAM was 7 mL and pH was 9, the stirring was divided into two stages, the first stage was stirred at 100 r/min for 40 s and the second stage was stirred at 200 r/min for 40 s, the total removal of microplastics could reach the highest value of 91%. (2) The main factors affecting the removal efficiency of microplastics was the dosage of PAC and pH. (3) The removal of microplastics was related to their density. ABS with a high density had the highest removal rate, while PE with the lowest density had the lowest removal rate. (4) The removal rate of microplastics varied greatly with their particle size, and the removal efficiency was highest in the range of 0.1-0.25 mm with small particle size. The study shows that by controlling the dosage of polyaluminium chloride and polyacrylamide, pH and stirring speed, the microplastics in wastewater can be effectively removed by flocculation and precipitation, so as to purify the wastewater containing microplastics.