热聚沉法处理紫胶漂白废水工艺

Modeling Optimization and Preliminary Mechanism Investigation on Shellac Bleaching Wastewater Treatment by Thermal Coagulation Method

为简便、有效地降低紫胶漂白废水中的SS含量,减小后续处理工艺的负荷,采用热聚沉方式分离废水中的SS,并通过单因素及响应曲面实验得到优化工艺条件。结果表明,紫胶漂白废水热聚沉的优化工艺条件,即处理温度55℃、恒温时间130 min、搅拌转速80 r/min,在此条件下,可将漂白废水滤液中的SS的质量浓度由1 489 mg/L降至237.6 mg/L,浊度由1 689 NTU降至420 NTU,COD由4.735 g/L降低至2.281 g/L,BOD5由2.46 g/L降低到1.64g/L。在此基础上,通过对废水及其SS微粒的结构、性质及形态等系列检测,表明废水中SS微粒的热聚沉经过了漂白紫胶的软化聚集及收缩沉降2个过程,其中软化是漂白紫胶微粒碰撞后聚集成长的动力,而收缩则是漂白紫胶微粒的物理形态变化并沉降的原因。

This work describes a simple and effective pretreatment process to remove the SS content and ease the subsequent processing burden and reduce suspended organic solids in bleached shellac wastewater by the thermal coagulation method. The methods of single factor and the response surface are used for this experiment. Meanwhile the optimum experimental conditions can be obtained such as reaction temperature of 55 ℃, thermostatical time of 130 rain and stirring rate of 80 r/min. The value of SS, turbidity, COD and BOD5 in the sample decreased respectively from 1 489 mg/L, 1 689 NTU, 4 736 mg/L and 2 460 mg/L to 237.6 mg/L, 420 NTU, 2 281 mg/L and 1 640 mg/L after the thermal coagulation treatment. The principle of coagulation by characterizing the structure, properties and morphology of SS in the sample is proposed preliminarily in this article. There are two processes about the phenomenon of thermal coagulation. The two processes include the softening aggregation and the contraction settlement. The softening is the basis of aggregation of shellac solids. And the contraction is the reason of settlement of shellac solids. So it concludes that the thermal coagulation of the shellac solids related to the effect of the two processes above.