| More and more researchers have paid an attention to bio-drying, which is a new kind of biomass energy utilization technology, and can be used as an economic, effective and environmental pretreatment technology of dewatered sewage sludge. After bio-drying process the moisture content and viscosity of dewatered sludge can be reduced, this is conducive to the transport, storage and further disposal of dewatered sludge. However, the dewatering efficiency of bio-drying process for dewatered sewage sludge remains to be further optimized. Taken the dewatered sewage sludge as the study object, influences of air-flow, an additional carbon source and a compound microbial preparation on bio-drying of dewatered sewage sludge were studied.Results showed that under the premise of a certain total air quantity, the alteration of air-flow rate in ventilation process was conducive to the improvement of dewatering efficiency of bio-drying process for dewatered sewage sludge. The air-flow rate changed from large to small, compared with no alteration, through6days of experiment the material TC of the alterative trial was decreased by17.5%. The material VS degradation rate of the alterative trial was1.42percent lower than that of contrastive trial, but its material moisture removal rate was2.48percent higher than that of contrastive trial.Adding an additional carbon source facilitated the second increase of the temperature of material, which promoted the moisture removal and VS degradation of material, eventually the material weight loss rate and the dewatering efficiency of bio-drying process for dewatered sewage sludge were improved. Compared with no addition, the addition of a1.25%(w/w, raw sludge) additional carbon source on the fourth day increased the TC of material by50.43%after8days of experiment, and the moisture removal rate, VS degradation rate and weight loss rate of added material are2.95,4.94and1.69percent higher than that of no added material respectively.The optimal conditions of the proportion of carbon source and compound microorganisms were as follo wings:carbon source (2g/200g, raw material) and compound microorganisms (0.8g/200g, raw material). Inoculating a compound microbial preparation substantially increased the microbial population and the temperature of material, extended the high temperature phase, and improved the VS degradation rate, moisture removal rate and weight loss rate of material. Consequently, the material weight loss rate and the dewatering efficiency of bio-drying process for dewatered sewage sludge were improved, and the drying process was speeded up. Compared with no inoculation, the TC of inoculated material increased by58.08%after8days of experiment, and the moisture removal rate, VS degradation rate and weight loss rate of inoculated material are5.97,7.22and4.75percent higher than that of no inoculated material respectively.The results of this paper provide scientific basis for the further optimization and application of dewatered sludge bio-drying and it provide reliable guarantee for the further treatment and disposal of dewatered sewage sludge. |
PDF Full Text Request