罗非鱼养殖尾水絮凝去除效果研究

Study on the flocculation removal effect of tilapia farming effluent

罗非鱼养殖尾水中含有大量的残饲和粪便等颗粒悬浮物,这些物质是氮、磷营养元素的主要载体。将养殖尾水外排会导致周边水体富营养化。当前常见的尾水处理方式具有占地面积大、投资高、效率低等缺点,影响其推广使用。为解决这一问题,探索采用絮凝工艺对罗非鱼养殖尾水进行处理,选取聚合硫酸铁、三氯化铁、壳聚糖和碳酸镁等4种絮凝剂,通过比较浊度、总悬浮物和化学需氧量的去除效果,筛选出适合用于养殖尾水处理的絮凝剂。结果显示:聚合硫酸铁的效果优于其他3种絮凝剂。在投加量0.4 g/L、pH=8、絮凝时间15 min时,聚合硫酸铁对养殖尾水的浊度、总悬浮固体颗粒物(TSS)和化学需氧量(COD)的去除率分别达到了96.7%、92.6%和95.1%。对絮凝后絮体评价发现,絮体的沉降高度与浊度去除率具有一定相关性,絮体的成长受成核作用的影响。尾水处理前后的zeta电位说明聚合硫酸铁通过破坏尾水中的悬浮物的稳定结构而净化尾水。研究表明,在罗非鱼养殖尾水处理时,可选择聚合硫酸铁作为絮凝剂。

Tilapia farming effluent contains a large amount of suspended particles such as uneaten feed and feces,which are the main carriers of nitrogen and phosphorus nutrients.Discharging the effluent into surrounding water bodies can lead to eutrophication.The common effluent treatment methods currently have disadvantages such as large land occupation,high investment,and low efficiency,affecting widespread adoption.To address this issue,this paper explores useing the flocculation process to treat tilapia farming effluent,selecting four flocculants:polyferric sulfate,ferric chloride,chitosan,and magnesium carbonate.By comparing the removal effects on turbidity,total suspended solids(TSS),and chemical oxygen demand(COD),a suitable flocculant for effluent treatment is selected.The results show that polyferric sulfate outperforms the other three flocculants(ferric chloride,chitosan,and magnesium carbonate).With a dosage of 0.4 g/L,pH=8,and flocculation time of 15 minutes,polyferric sulfate achieved removal rates of 96.7%for turbidity,92.6%for TSS,and 95.1%for COD.Evaluation of the flocculated flocs revealed that the height of floc settling has a certain correlation with the turbidity removal rate,and the growth of the flocs is affected by nucleation.The zeta potential before and after effluent treatment suggests that polyferric sulfate purifies the effluent by disrupting the stable structure of suspended particles in the water.Therefore,polyferric sulfate can be selected as a flocculant in treating tilapia farming effluent.