| With the constant improvement of the urban sewage treatment capacity in China,sludge production is also increasing rapidly. Proper disposal of sludge has become a hotand difficult problems in the field of wastewater treatment. Based on the research aboutthe dewatered sludge cake drying and deodorizing of a wastewater treatment plant inJi’nan, sludge drying pilot test system by solar energy and heat pump technology（SHP）was build to investigate the effect of sludge drying by using the combination techniqueof solar greenhouse and reclaimed water source heat pump under different conditionsincluding seasons, weather, temperature and humidity. The optimum operating modeand process control parameters of the SHP system for sludge drying was discussed, inthe mean time,direct at odor problems generated in the sludge drying process,afunctional bacterial strain with high protein degradation characteristics was isolatedfrom sludge through the identification and screening by using molecular biologytechniques. And the deodorization effect of composite deodorant bacteria made by thefunction bacteria and other biological bacteria was investigated.Through sludge drying experiment in the use of solar assisted reclaimedwater-source heat pump technology, it was found that SHP system had goodperformance of dehumidification and thermal insulation. Sludge drying rate was mainlycontrolled by temperature, in contrast, humidity had little effect on sludge drying rate.Sludge drying efficiency by using SHP system was highest in the summer. For the slugewith moisture content range of75%~80%, the drying time was2d~3d when slugemoisture content below55%, and the highest Sludge moisture removal rate can up to7.1%/d. Under low temperature in winter, the system drying efficiency can bestrengthened by adding drier. Sludge drying was mainly to remove extracellular waterthrough the analysis of digital microscopic. Its mechanism of action was to remove thebound water after the extracellular water, and the removal efficiency of the bound waterwas determined by the degradation rate of polysaccharide hydrophilic substance inextracellular polymer.Based on the identification and screening of microbial population, a functionalbacteria strain with high protein degradation characteristics, bacillus subtitles, whichcan made composite deodorant inoculants with lactobacillus acidophilus by cultivating fermentation, was isolated from sludge.Dosing the compound deodorized bacteriumagent could reduce odor release quantity of90%such as ammonia, hydrogen sulfide inthe SHP system, which shows a good effect of deodorization.Through the economic analysis, the processing cost of dry sludge is about148yuan per ton(Including construction investment and depreciation of facilities). Sludgedrying and deodorization by using this technology has obvious advantages in cost.In conclusion, this study further explored the technical feasibility of solar energycombined with reclaimed water source applied to urban sewage treatment plant sludgedrying, and has made clear the application effect of the functional bacteria in sludgedeodorant. The study provides a scientific basis for engineering practice of the sewagetreatment plant sludge drying and deodorization, which has a certain guidingsignificance. |
