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Advanced treatment process for hot spring wastewater containing arsenic

含砷温泉废水深度处理工艺

基本信息

批准号：
08458161
负责人：
NOIKE Tatsuya
金额：
$ 4.67万
依托单位：
TOHOKU UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1996
资助国家：
日本
起止时间：
1996 至 1997
项目状态：
已结题

项目摘要

Inorganic arsenic compounds are commonly observed in solution as AsO_2^- and AsO_4^<3-> and these oxo-anions are typically water soluble. Arsenic does not form an insoluble hydroxide and can be removed by coprecipitation system. The most important mechanism for the accumulation of arsenic in sludge settling tank during wastewater-sludge interaction is adsorption on and coprecipitation with hydrous iron oxides in contaminated wastewater. Hydrous iron oxides is a suitable coagulant for the removal of arsenic than aluminum compounds. Hydrous iron oxides were a effective coagulant even if the influent were highly contaminated with arsenic (1.5mg/1). The aluminum compounds did not reduce the arsenic concentration of the discharged wastewater to 0.1mg/1 of the limitation level of discharged wastewater when the influent was highly contaminated with arsenic (1.5mg/1). Amount of sludge volumes which were produced during the wastewater treatment process was not effected by the species of coagulants but by the amounts of coagulants. The activity of activated sludge in oxidation ditch was not affected by 20 mg/1 of hydrous iron oxides. The concentration of iron in the discharged wastewater was increased with increasing the amount of coagulant (hydrous iron oxides) added to the modified oxidation ditch process. The concentration of coagulant added to the chemical sedimentation tank needed lower than that added to the oxidation ditch to attain the same arsenic removal efficiency.

无机砷化合物通常以AsO_2^-和AsO_4^-的形式存在于溶液中<3->，这些含氧阴离子通常是水溶性的。砷不形成不溶性氢氧化物，可通过共沉淀系统去除。污泥沉降池中砷的积累主要是通过与废水中的水合氧化铁吸附共沉淀而实现的。水合氧化铁是一种较好的除砷混凝剂。即使在高砷（1.5mg/l）的进水中，水合氧化铁仍是一种有效的混凝剂。当进水砷浓度为1.5mg/l时，铝化合物不能使出水砷浓度降至0.1mg/l的排放限值。混凝剂的种类对污水处理过程中产生的污泥量影响不大，而与混凝剂的投加量有关。20 mg/l的水合氧化铁对氧化沟活性污泥的活性没有影响。随着混凝剂（水合氧化铁）投加量的增加，出水铁浓度增加。化学沉淀池投加的混凝剂浓度要低于氧化沟投加的混凝剂浓度，才能达到相同的除砷效果。