ELUCIDATION OF REMOVAL MECHANISM OF ARSENIC FROM SEWAGE SLUDGE AND INCINERATED ASH OF SEWAGE SLUDGE AND DEVELOPMENT OF ITS REMOVAL METHOD

碱性条件下污泥中砷的溶出量大于酸性条件。碱化污水污泥的pH 9和11洗脱砷超过80%和95%，分别。结果发现，从污泥中洗脱的砷的主要形式是砷酸在pH值为5，7，9和11，通过使用HPLC-MS，而它是亚砷酸在pH值为1。与砷和亚砷酸相比，一甲基胂酸和二甲基胂酸的洗脱量较小。这一结果表明，砷的洗脱形式取决于砷在水体系中的pH-EH图。结果表明，在酸性条件下，铁氧化菌和三价铁的加入能有效地氧化污泥中的硫化砷，使砷溶出，从而实现污泥焚烧灰中砷的连续溶出。通过添加含有来自消化气体的脱硫过程的硫的废物和在消化的污水污泥中存活的硫氧化细菌，灰分的pH下降到1以下。实验结果表明，在固体停留时间为10天、灰中固体浓度为20 gD.S/L、垃圾浓度为20 gW. T/L的条件下，可连续洗脱出80%以上的砷。L.

Alkaline condition eluted arsenic in the sewage sludge more than acidic one. Alkalization of sewage sludge to pH 9 and 11 eluted arsenic more than 80 and 95%, respectively. It was found that the predominant form of arsenic eluted from the sludge was arsenic acid at pH5, 7, 9 and 11 by using a HPLC-MS, whereas it was arsenious acid at pH1. The eluted amount of of monomethylarsonic and dimethylarsinic acids was small compared with those of arsenic and arsenious acids. This result indicated that the form of arsenic eluted depended on the pH-EH diagram of arsenic in an aqueous system. It was shown that the addition of iron oxidizing bacteria and ferric iron was effective for the elution of arsenic on the acidic condition since arsenic sulfide in the sludge was oxidized by them and it caused the elution of arsenic.The possibility of continuous arsenic elution from incinerated ash of sewage sludge was studied. The pH of ash dropped below 1 by adding waste containing sulfur produced from desulfurization process of digested gas and sulfur oxidizing bacteria surviving in the digested sewage sludge. It was found that more than 80% of arsenic in incinerated ash could be eluted continuously on the condition of a solid retention time of 10 days, solid concentration of ash of 20 gD.S/L and waste concentration of 20gW.T./L.