Effect of different surfactants on removal efficiency of heavy metals in sewage sludge treated by a novel method combining bio-acidification with Fenton oxidation

REN Miao-miao(任苗苗)^{1, 2}, YUAN Xing-zhong(袁兴中)^{1, 2}, ZHU Yi(朱艺)^{1, 2}, HUANG Hua-jun(黄华军)^{1, 2}, ZENG Guang-ming(曾光明)^{1, 2}, LI Hui(李辉)^{3, 4}, CHEN Ming(陈明)^{1, 2}, WANG Hou(王侯)^{1, 2}, CHEN Chang-ya(陈畅亚)^{1, 2}, LIN Ning-bo(林宁波)^{1, 2}

(1. College of Environmental Science and Engineering, Hunan University, Changsha 410082, China;
2. Key Laboratory of Environment Biology and Pollution Control of Ministry of Education
(Hunan University), Changsha 410082, China;
3. Hunan Academy of Forestry, Changsha 410004, China;
4. Hunan Engineering Research Centre for Biodiesel, Changsha 410004, China)

Abstract:The aim of this work was to investigate the effect of different surfactants on the removal efficiency of heavy metals in sewage sludge treated by a method combining bio-acidification with Fenton oxidation. Four surfactants were adopted such as anionic surfactant (sodium dodecyl benzene sulfonate, SDBS), nonionic surfactants (tween-20 and tween-60) and cationic surfactant (hexadecyl trimethyl ammonium chloride, HTAC), respectively. The indigenous sulfur-oxidizing bacteria in bio-acidification phase were enriched and cultured from fresh activated sludge obtained from a wastewater treatment plant. It is shown that different surfactants exhibited distinct effect on the removal efficiency of heavy metals from sewage sludge. The nonionic surfactants, especially tween-60, promotes the solubilization of heavy metals, while the anionic and cationic surfactants hinder the removal of heavy metals. Copper is efficiently leached. The removal efficiency of cadium is relatively lower than that of Cu due to the demand for rigorous pH value. Lead is leached with a low efficiency as the formation of low soluble PbSO₄ precipitates.

Key words:sewage sludge; heavy metals; surfactants; bio-acidification; Fenton oxidation