Research On Pre-acidifwication Microwave Chemical Leaching Removal Of Heavy Metals In Sewage Sludge

In the "twelfth five-year" period, the sludge land use has become a hot research. The heavy metals in sludge was the most main factors that hinder its land use. In this paper based on early discovers’ research results which using microwave chemical leaching removal of heavy metals in sludge, in order to reduce subsequent acid quantity.Analysis and research on preacidification process parameters and pre-acidification microwave chemical leaching process treatment effect. The result are as follows.By changing the temperature, stirring rate and sludge inoculation amount, this paper research the process parameters of most quickly reduce concentrated of sludge’s p H. The results show that, in conditions of 35℃, 30% inoculated pre-acidification sludge, and control the stirring speed is 80-100 r/min, can make the concentrated sludge’ p H reduced to6.5 within 36 h.By changing the subsequent citric acid content, this paper research the subsequent changes the removal rate of heavy metals in sludge. The results show that, when reducing20% citric acid, the acidification sludge mixture p H also can reduce to 4, but at that moment, heavy metal removal rate is lower than usual. As the acid volume continues to increase, heavy metal removal rate showed a trend of rise. When the citric acid to reduce the amount of 10%, the result of heavy metal removal also can attain the removal effect of microwave chemical leaching process,then the Cu, Pb, Zn, Ni removal rate was 54.85%,55.21%, 59.30%, 55.69%By comparing the different sludge properties after processing, this paper analysis and research the effect of Pre-acidification process on the original process and the effect of new technology of processing. The results show that the Zn, Pb, Ni content of sludge after acidizing process compare to concentrated sludge is reduced about 5%. What is more, Cu has a little change. For the sludge after new process, the heavy metal removal rate is little difference from the original process, but the stable states of heavy metals in sludge which after new process treatment is higher. In addition, after new process treatment sludge moisture content, sedimentation performance indicators, is no obvious changes. However such as the content of organic matter, TN, TP, K content is lower, but the sludge still has good effectiveness.