臭氧对养殖水体中颗粒物的絮凝和破碎作用

Flocculation and Fragmentation of Particulate Matter in Biofloc Culture Water by Ozone

为探明臭氧对水产养殖污水中悬浮颗粒物的絮凝和破碎作用,使用不同质量浓度臭氧对循环水生物絮团对虾养殖系统中水体进行氧化处理,并对水体中的水质指标、悬浮颗粒物粒径分布变化等进行分析,试验结果显示:不同质量浓度臭氧处理使水体中氨氮、硝态氮含量显著升高(P<0.05),亚硝态氮含量显著下降(P<0.05);不同质量浓度臭氧处理后水体中总悬浮物含量显著下降(P<0.05),随臭氧质量浓度的增大,总悬浮物去除率逐渐升高,臭氧质量浓度为2.5mg/L时去除率最高(23.15%);臭氧输入养殖水体后,水体中悬浮颗粒物的粒径分布出现明显变化,随臭氧质量浓度增加絮凝效率逐渐升高,臭氧质量浓度为2.5mg/L时,絮凝效率最高(33.61%)。试验结果表明,臭氧能够有效去除水体中亚硝态氮,并对水体中的悬浮颗粒物有絮凝作用。建议处理养殖用水适宜的臭氧质量浓度为1.5 mg/L,适宜的作用时间为4min。

In order to understand the effect of ozone on flocculation and fragmentation of suspended particulate matter in aquaculture wastewater,the ozone concentrations corresponding to 0.5,1.0,1.5,2.0 and 2.5 mg/L were aerated by an ozone generator for 5,10,15,20 and 25 s in a 1 L ozone reaction vessel at a water temperature of(29±1)°C,respectively.Each ozone concentration was oxidized with the raw water in the circulating water biofloc shrimp culture system in Sanmao Aquaculture Farm in Songjiang District,Shanghai for 1,2,3,4 and 5 min,and each combination test was repeated 3 times.Immediately after the treatment,the water quality index,the concentration of total residual oxidant(the concentration of total residual oxidant determined immediately at the end of aeration)and the particle size distribution of suspended particulate matter were measured in the water samples.The results showed that different ozone concentration treatments caused significantly increase in the levels of ammonia nitrogen(NH+4-N)and nitrate nitrogen(NO-3-N)contents in the water(P<0.05),with significant decrease in nitrite nitrogen(NO-2-N)level in the water column(P<0.05).There was significant decrease in total suspended solids(TSS)in the water(P<0.05)with different concentrations of ozone treatment,and the gradual increase in the removal rate of TSS with the elevated ozone concentration,with the maximum removal rate of 23.15%at ozone concentration of 2.5 mg/L.The size distribution of suspended particles in the water was found to be changed significantly after the ozone was put into the culture water,with gradual increase in the flocculation efficiency with the increase in ozone concentration,and the maximum flocculation efficiency of 33.61%at the ozone concentration of 2.5 mg/L.The findings indicated that ozone effectively removed nitrite nitrogen and flocculated suspended particles in the water.It is recommended that treatment of aquaculture waterbe conducted at the suitable ozone concentration of 1.5 mg/L for 4 min.