添加小分子有机物对污泥重金属生物沥滤的抑制作用

The discussion of the effect of different low molecular weight organic compound addition on the heavy metals bioleaching from sludge

采用向城市污泥添加小分子有机物后进行生物沥滤,探讨了不同小分子有机物(甲酸、乙酸、丙酸、丁酸、乙醇、水杨酸、草酸、苯甲酸)对生物沥滤过程污泥中pH值、Eh、Cu含量和Zn含量的影响。结果表明,对于污泥中的pH和Eh,不同有机物对其影响程度在整个沥滤过程中大体上相似,即pH值都呈先升后降的趋势,Eh呈先降后升趋势。对不同类型的重金属来说,不同有机物对其影响程度Cu大于Zn,其中Cu的沥出效果从强到弱依次为:对照>苯甲酸>乙醇>草酸>水杨酸>丙酸>甲酸>丁酸>乙酸,而对Zn的沥出效果在整个沥滤过程中相似。总之,整体规律为:醇类化合物和二羧基酸对污泥中的硫细菌的生物沥滤影响不大,而对于结构相似的单羧基有机酸来说,碳链越短,对生物沥滤的影响越大,分子量较高的芳香族有机酸对于重金属的去除也有明显的抑制作用,影响程度随着羧基数目的增加而加剧,但其抑制作用不及小分子有机酸显著。此外,污泥中营养物质TN、TP和TK的释放也受到一定影响。

The article investigated the effect of different low molecular weight organic compounds （i.e. formic acid, acetic acid, propionic acid, butyric acid, ethanol, salicylic acid, oxalic acid, benzoic acid） addition on the pH, oxidation-reduction potential （Eh）, contents of copper （Cu） and zinc （Zn） from bioleached sludge. Our results showed that the addition of different organic compounds had mainly opposite effects on the pH and Eh during the whole bioleaching process. For heavy metals, addition of organic compounds had greater effects on Cu than Zn, and the bioleaching efficiency of different organic compounds on Zn followed similar patterns. And according to the magnitude of bioleaching efficiency of different organic compounds on Cu, we can order the effect of different treatments as following： control〉 benzoic acid〉 ethanol〉 oxalic acid〉 salicylic acid〉 propionic acid〉 formic acid〉 butyric acid〉 acetic acid. All in all, we found that the effect of the alcohol compound and the two carboxyl acid addition on bioleaching with sulphur bacteria was slightly. And we also indicated that the effect of bioleaching on sulphur bacteria decreased with increasing carbon chain＇s length for single carboxylic organic acids. Aromatic organic acid addition restricted the bioleaching effect on heavy metals, and the restriction effect increased with increasing number of carboxyl, while the magnitude of this restriction effect was lower than that of organic acid with low molecular weight. Furthermore, the release of total nitrogen, phosphorus and calcium was also influenced by addition of organic compounds to the sludge.