化学絮凝法处理温室龟鳖养殖废水工艺参数优化

选择聚合氯化铝(PAC)、聚合硫酸铁(PFS)、聚合氯化铁(PFC)为絮凝剂,对比研究3种絮凝剂去除温室龟鳖养殖(greenhouse turtle aquaculture)废水悬浮物效果。结果表明,絮凝剂PAC的絮凝效果最佳。选择PAC为絮凝剂,阳离子聚丙烯酰胺(PAM)为助凝剂,通过响应面法以浊度去除率为响应值,PAC和PAM的投加量和搅拌时间为影响因素,对工艺关键参数进行优化,最终确定最佳工艺参数。根据响应面分析结果,确定龟鳖养殖废水的最佳絮凝条件为PAC质量浓度85.3 mg/L、PAM质量浓度19.8 mg/L、搅拌时间2 min。在此条件下浊度去除率为97.1%,为温室龟鳖养殖废水的优化絮凝处理提供了参考依据。

Optimization of key operating parameters of coagulation for treating turtle aquaculture sewage

This study aims at optimizing the key operating parameters of coagulation process for removing the suspended solids (SS) from the greenhouse turtle aquaculture (GTA) wastewater in terms of turbidity removing rate through comparing the turbidity removal due to different coagulants.For the said purpose,we have adopted the response surface methodology (RSM) and established a model for predicting the turbidity removal efficiency.As a matter of fact,it would be possible to identify and determine the proper performance for removing the turbidity from GTA sewage by comparing the polymerized ferric sulfate (PFS),the polymerization ferric chloride (PFC) and the poly aluminium chloride (PAC),proving that the turbidity removal rate increases with the increasing addition of PAC.The maximum turbidity removal rate can be made as high as 91％ at PAC of 120 mg/L.What is more,PAC can also be used with the cationic polyacrylamide (PAM) as the coagulant aid to treat GTA sewage.Furthermore,we have also found that it has been indeed optimistic to achieve the highest possible turbidity removal rate by using RSM with the three key independent operating parameters of PAC-PAM coagulation,that is to say,PAC concentration,PAM concentration and the mixing time whereas a corresponding quadratic curved surface model for predicting turbidity removal rate is established via Design-Expert 9.0 software.We have also found that the optimal combination of the selected key operating parameters can be determined as follows:PAC:85.3 mg/L;PAM:19.8 mg/L and the mixing time:2 min,with the corresponding highest turbidity removal rate being at 97.1％.In addition,it has been found that the turbidity removal rate can be significantly affected by the linear term of PAC concentration,the quadratic term of PAC concentration,PAM concentration and mixing time,and the interaction term of PAC concentration as well as PAM concentration.Moreover,R2 value of the quadratic curved surface model has been found equal to 0.988 7,while the predicted value generated from the model has been verified close to the experimental data.As such,RSM proves to be an appropriate approach to optimizing the operating parameters of the coagulation process proposed in this paper.