Effect Of Different Surfactants On The Removal Efficiency Of Heavy Metals In Sewage Sludge Treated By A Novel Method Combining Bio-acidification With Fenton Oxidation

Modern industrial society makes the productivity and people’s living standardsimproved greatly, but on the other hand, the production of industrial waste and lifewaste increase accordingly. Sewage treatment plant will produce a lot of excess sludgewhich is difficult to deal with every year. The processing cost of excess sludgeaccount for60%in the total processing cost of in wastewater treatment plant. As thesludge contains a lot of nutrients, so the excess sludge is usually used as soil fertilizeror a soil conditioner. But the heavy metal contained in the sludge limits the recycle ofthe excess sludge. Therefore, the removal of heavy metals in sewage sludge hasbecome a problem to be solved.In this paper, the method of surfactants combined with biologicalacidification-Fenton oxidation is used to remove the heavy metals in sewage sludge.Five surfactants were adopted in this research such as anionic surfactant (sodiumdodecyl benzene sulfonate, SDBS), nonionic surfactants (tween-20, tween-60andtween-80) and cationic surfactant (Hexadecyl trimethyl ammonium chloride, HTAC),respectively. This experiment inoculates sulfur oxide thiobacillus mixed bacterialiquid. Sulfur powder is added in the inoculation as the substrate and five kinds ofsurfactants are also added into the system. When pH decreases to below3, Fentonreagent (Fe2+and H2O2) is added into the rest of sludge sample. The effect of differentsurfactants on the removal efficiency of heavy metals in sewage sludge treated by anovel method combining bio-acidification with Fenton oxidation is studied in thisresearch. From the results of the experiment, the tween-60run obtains the highestheavy metal removal under the condition: sludge containing solid rate (2%)、sulfurpowder concentration（8g/L）、 the surfactants concentration（4g/L）、FeSO4·7H2O（6.21g/L）and H2O2(10g/L). The experiment is in duplicate.Afterwards, another test is processed with tween-60which was selected to be thebest option to help to remove heavy metals from sewage sludge. The most suitableconcentration of tween-60in sewage sludge system becomes the focus problem. Thecontents of tween-60are setted into six patterns:0g/L、2g/L、4g/L、6g/L、8g/L、10g/L.The other conditions of this research are the same with the front. Theexperiment is in duplicate. From experimental result, when the concentration oftween-60is4g/L, removal of heavy metals is the highest. Therefore, the method of combining surfactants and sewage sludge biological acidification-Fenton oxidationtreating heavy metals in excess sludge is feasible. Heavy metals are removed out ofthe sludge greatly, and the toxicity of the sludge is reduced significantly.