Primary Study On Bio-drying And Maturing Of Rural Biodegradable Waste

With the beautiful countryside and the rural revitalization strategy,the rural environmental renovation work in China has been continuously accelerated,and the pilot work of rural domestic waste(RDW)classification and treatment has been implemented steadily.After several years of practice,the construction of classified deposit,collection,transportation and treatment system of RDW has achieved preliminary results.Taking Hangzhou as an example,through the investigation of the status of RDW classification and resourcing treatment,it is found that the source classification of RDW in pilot villages and towns has achieved remarkable results,but the resourcing treatment of biodegradable waste generally has bottlenecks such as high water content and low maturity of products.In order to solve this technical problem,a set of high-efficiency and low-consumption bio-drying and fast-maturing processes for biodegradable waste in rural areas was designed,and corresponding experiments were carried out.Combining reaction kinetics and thermodynamic calculation,the energy and water balance of the process was calculated.The main results are as follows:(1)The dichotomy method(biodegradable waste and other waste)is appropriate for RDW,but the product quality of biodegradable waste resourcing treatment technology is poor.According to the survey,the content of biodegradable waste(>50%)is the highest in the physical components of RDW in Hangzhou.The dichotomy method is helpful to achieve the source separation and in-situ reduction of biodegradable waste.However,at present,the quality of products is generally not up to standard,which indicates the most prominent problem is the high moisture content and low maturity of bio-drying products.(2)A new bio-drying and maturing reactor for biodegradable waste in rural areas was designed.The effects of ventilation frequency,stirring frequency and heating mode on bio-drying and maturing of biodegradable waste were systematically investigated.Results showed that the maturity and the net growth of low heating value(LHV)of the products was the highest when ventilation frequency was '10 min on/20 min off',compared with the treatment of '10 nmin on/30 min off'and '10 min on/10 min off';And the maturity and the net growth of LHV of products obtained by 3 times d-1 stirring frequency were significantly higher than that of 2 times ·d-1 and 4 times d-1;Besides,the maturity and the net growth of LHV of products under intelligent heating mode were significantly better than that of continuous heating mode.(3)Optimizing the ventilation strategy in the process of bio-drying and maturing is the most important way to improve the dewatering performance of materials.The calculation of energy and water balance shows that the main energy input in the process of bio-drying and maturing is the heat of bio-reaction(66.78%),while the input of exogenous heating accounts for a small proportion(6.41%);The main energy output is the heat loss of reactor(46.60%)and the latent heat of vaporization of water(39.04%).The main way of water removal is through the convective evaporation mechanism of material moisture(accounting for 80.01%of the water reduction)realized by ventilation.Therefore,if the dewatering performance of materials is to be significantly improved,it is necessary to optimize the ventilation strategy in the process of bio-drying and maturing.Intelligent heating mode and enhancing the thermal insulation performance of the reactor can achieve high efficiency and low consumption of bio-drying and maturing technology.