The Research Of Kinetics Process Of Co-digestion Under The Condition Of Thermostatic And Batch Mode

With the rapid development of urbanization and the improvement of people’s living level in China, animal and human excreta, straws, fruit and vegetable wastes, domestic sewage and other waste seriously pollute the local environment. The innocent treatment of them has become one of key problems that Chinese rural urbanization need urgently resolve. As a kind of efficient low-cost recycling method of hybrid organic wastes, technology of co-digestion under the condition of thermostatic and batch mode can widely used in household biogas project, biogas generation in refuse landfills, dry anaerobic fermentation and so on.Research on this technology, the key is to analyze its fermentation kinetics processes under the condition of batch feed and constant temperature, which contains the kinetics process of methane produced during anaerobic fermentation process, acid-base balance kinetics process, matrix degradation kinetics, microbial growth kinetics and the generation kinetics processes of other gases and hazardous substances generation processes. The study approach is to establish the batch co-digestion mathematical model under the thermostatic temperature, and determine some parameters of the model required through a number of experiment, contains methane production rate, the change of pH value, and other gases production of harmful gases,which was used in correction model with the simulation results and experimental results to study the kinetics process of co-digestion under the condition of thermostatic and batch mode.This paper use rural wastes as experiment materials, studied on the main influence factors in anaerobic digestion from aspects of temperature、TS and mixing ratio. Studied degradation process of co-digestion under the condition of Thermostatic, arriving at the following main reviews:1. Analyzed Gas properties of sole cattle dung in anaerobic digestion experiment under the condition of Thermostatic, contrasted three fermentation temperature, found that:the group of37℃has the highest biogas production, respectively0.21,0.31,0.33and0.36m3/kgTS, the reason is that methanogens has high-activity at37℃, so does hydrogenogens, Substrate degrade to methane quickly and degradation rate of fermentation materials is high; due to combined action of TS and temperature, group of TS8%has the highest biogas production. Therefore, sole cattle dung owned optimum fermentation production under the condition of TS8%,37℃.2. Analyzed the influence of temperature on anaerobic digestion experiment, including cattle dung mixed with maize straw and lotus respectively, thermophilic fermentation reflected quickly and shortened fermentation period as a prerequisite to TS8%,contrasted with the group of37℃, the former managing complex and enhancing the operation cost, thus choosing the fermentation temperature37in batch fermentation.3.Through the anaerobic digestion experiment of livestock and poultry manure mixed with cabbages, contrastively analyzed the starting time, average methane content and average methane productivity of digestion experiment on different livestock and poultry manure mixed with cabbages. The mixing ratio of pig manure with cabbages is7:3, which average methane productivity higher43.01%and10.51%than cattle dung and sheep manure on optimal mixing ratio. The optimal mixing ratio of livestock and poultry manure mixed with cabbages is7:3.4. Corn stalks, straw with cabbages mixed fermentation has the optimal mix ratio are all7:3, the fermentation of straw mixed with cabbages has a better effect with the ratio of9:1and7:3.But three materials were respectively mixed with cabbages fermented, start-up time is very long, thus increasing the amount of vaccination reducing the time to acidification, quick access to methanogenic stage. Whatever the mixing ratio of food waste and cabbage is, the normal gas production time and the peak gas production time is long and fermentation prone to failure, only adding dosing of100ml biogas slurry with pH7.48on the12th day during the fermentation process, fermentation continues,this indicating that beef noodle-based waste food is not suitable for mixing with cabbages for fermentation.5. TS for8%of the cattle manure37℃anaerobic fermentation model and TS for8%mixing ratio of1:1of cattle manure mixed lotus dish37℃anaerobic fermentation model were established based on ADM1model and using Excel-matlab, Pure cow model compared with the measured values can be well predicted cumulative production of methane, the cumulative production of carbon dioxide, methane cumulative production in TS8%of37℃cattle manure batches anaerobic fermentation, the longer fermentation time, The closer the predicted values and measured values; the model in predicting the fermentation process, including most of the anaerobic fermentation of equations, and contains most of the anaerobic fermentation parameters, so that some of the fermentation process can be omitted in the actual testing, avoiding the introduction of m test instruments affected in the fermentation process and without affecting understand the fermentation dynamics process, the mixed fermentation model of cattle manure mixed lotus dish can accurately predict the cumulative gas production of20days,surpassing20days, the results have Large difference.The innovation of the paper concludes that:(1) This subject studied kinetics process of co-digestion under the condition of thermostatic and batch mode with different temperature, TS and mixing ratio through the sufficient number experiments. Due to full and accurate experiments, the results not only provide the needed data in this subject,they can also be used as a relatively accurate experimental database for scholars and staff in related industries. (2) This subject first time comprehensively studied the influence of different organic waste on methane production in a different mixing ratio, the fermentation temperature, the solid concentration, pH, alkalinity and other conditions, proposed fermentation parameters and mathematical model, constructed ADM1model of cow dung mixed with fermented vegetables lotus, made up for the deficiency that relying on qualitative analysis of the experimental results can only quantitatively analyze the fermentation kinetics process.these organic waste contains fruit and vegetable wastes, excrements of livestocks, straw and food waste,,This work was supported by The State863Project(2014AA052801601), The State Ministry of Science, Technology Support Projects(2011BAD15B03), Natural Science Foundation of China (51366009),The Science Fund Program for Distinguished Youth of Gansu Province (2012GS05601), The Construction Science and Technology Development Program of Gansu Province (JK2010-29), The Education Department Program of Gansu Province(0803-06), The Tamarisk Outstanding Talent Program of Lanzhou University of Technology (Q201101).