Abstract:

According to the characteristics of low temperature and low turbidity of seawater in Jiaozhou Bay in winter，a combined process system：coagulation，air flotation，filtration and coagulation and filtration were designed. The pretreatment effect and operation stability of the two processes were investigated under the operating conditions of PAC dosage of 10 mg/L and filtration rate of 8 m/h. The test showed that after air floating and precipitation，the effluent SDI₁₅ stability was stable less than 3.0，the turbidity less than 0.4 NTU. COD_Mn less than 2.0 mg/L，mass concentration of iron and aluminum colloid less than 0.05 mg/L and mass concentration of silica colloid less than 0.2 mg/L. It reached the requirement of the water quality of the reverse osmosis membrane. The water quality of the coagulation and filtration process was obviously poor. According to the comparative analysis of the operating costs of the air flotation and filtration process and the ultrafiltration process，the electricity and pharmaceutical costs of the air flotation and filtration process were lower than the ultrafiltration process，which was as low as 0.186 3 yuan/m³. Considering the water quality，stability and economy of operation，the air flotation and filtration process was superior to the coagulation and filtration process and ultrafiltration processes.

Key words: low temperature and low turbidity, high-efficiency pretreatment process, seawater

摘要：

针对胶州湾海水冬季低温低浊度的特点，设计了混凝+气浮+三级过滤和混凝+三级过滤工艺系统，研究了两种工艺系统在聚合氯化铝投加量为10 mg/L，滤速为8 m/h的运行条件下对低温低浊度海水预处理的效果及运行稳定性。结果表明：混凝+气浮+三级过滤工艺的出水淤泥密度指数（SDI₁₅）稳定小于3.0，出水浊度低于0.4 NTU，COD_Mn稳定小于2.0 mg/L，铁、铝胶体质量浓度低于0.05 mg/L，二氧化硅胶体质量浓度低于0.2 mg/L，UV₂₅₄低于1.8 mg/L，能够满足反渗透膜元件的进水水质要求，而混凝+三级过滤工艺的出水水质明显较差；通过混凝+气浮+三级过滤工艺与超滤工艺的运行成本对比分析发现，混凝+气浮+三级过滤工艺电费及药剂费均低于超滤工艺（约低0.186 3元/m³）。从出水水质、运行稳定性和经济性上考虑，在低温低浊度海水预处理工艺中，混凝+气浮+三级过滤工艺优于混凝+三级过滤及超滤工艺。

关键词: 低温低浊, 高效预处理, 海水淡化, 混凝过滤, 气浮

CLC Number: 

• P747