Study On Deep Dewatering Of Dredged Sludge By Bioleaching

With long term input of exogenous pollution and deposition of aquatic organisms,the quality of riverway water has got deteriorated,it became balck and stinking.Sludge dredging is an important method to eliminate the internal pollution of black and stinking water,but the dredged sludge has high water content and large volume,which need to be reduced.Bioleaching is a biological technology which make use of substitution,oxidation and acidification of natural microorganism such as thiobacillus and leptospirillum ferrooxidans to dredged sludge,whose reactions were mild and no secondary pollution.All the experiments under the condition of 28?and shake at 180rpm to reach the goal of the enhancement of dewaterability of dredged sludge and pathogenic microorganism inactivation.The contents of research include the effect of energy substances and analysis of bioleaching significantly influence.First of all,comparative analysis of the effects of different energy substances(Fe SO₄,bioleaching under the same dosage.Results showed that,when Fe S₂?6g/L?and S⁰?2g/L?was used as energy sources,the sediment resistance to filter?SRF?decreased more obviously,reaching 89.07%,corresponding to the shortest bioleached time.Therefore,the best energy substances were Fe S₂ and S⁰.Secondly,the effects of the amount of sulfur powder and the particle size on the dewatering were studied in the range of 1g/L⁴g/L and 20¹00 meshes.Results showed that,the drop rate of SRF of experiment with addition of 2g/L sulfur powder was the highest,which was up to 81.82%;the drop rate of SRF of experiments with addition of sulfur powder whose average particle size was less than 164?m was the highest,which was up to 81.92%.Therefore,the best dosage of sulfur powder was 2g/L,the average particle size of sulfur powder should be less than or equal to 164?m.According to the results of prophase orthogonal test,the effects of significant factors?inoculum dosage,initial p H value and solid content?on the efficiency of bioleaching were studied by single factor experiment under the conditions of adding 5g/L Fe S₂,2g/L S⁰ and aeration intensity was 0.6 L/min·L.Results showed that,when the inoculum dosage increased from 0%to 10%,the drop rate of SRF increased from 75.84%to 81.89%,increase inoculum dosage will promote the dewatering of dredged sludge within this range;when the initial p H value was 5,the improvement of dredged sludge dewatering performance was the best,the highest drop rate of SRF was 82.05%;when the solid content increased from 3%to 5%,the drop rate of SRF increased from 82.62%to 84.28%,increase solid content will promote the dewatering of dredged sludge within this range.Thus,the optimum technic parameters of bioleaching were as follows:the dosage of inoculum was 10%,the solid content was 5%and the initial p H value was 5.Under this condition,SRF decreased from 6.49×10¹² m/kg to 1.02×10¹² m/kg,CST decreased from 39.5s to 10.3s,inactivation rate of total bacterial,total coliform,fecal coliform were all more than98%.