Process Conditions Optimization Of Straw Anaerobic Fermentation Biogas Slurry

In recent years,China's large and medium-sized methane project under the national government strongly encouraged developing rapidly,reasonable and effective handling of biogas slurry has become the key of the governance environment pollution problem.This paper studies the following aspects based on the straw anaerobic digestion biogas slurry.In this paper,we firstly sampled the Biogas Project in Shenyang,Liaoning Province,and obtained samples of anaerobic digestion residue.The biogas slurry composition was analyzed from three aspects:nutritional status,toxic and harmful pollutants and hygienic conditions,and compared with the standard values.The results showed that:(1)The nutrient content of the biogas slurry was basically lower than that of the organic fertilizer,but the total available nutrient(available N,P,K)reached the standard value.The total nutrient content is lower than the standard value of the organic fertilizer;the total available nutrient is up to the standard value.(2)The nutrition composition of biogas slurry was lower than the biogas residue,which limited the biogas slurry fertilizer.(3)The biogas project biogas slurry biogas hygiene indicators most meet the standard requirements,the basic will not cause harm to crops and soil.(4)The contents of mercury,arsenic,cadmium,lead and chromium in the biogas slurry of the biogas project are lower than the standard value,and the content of copper is excessive.The effects of temperature,light conditions,oxygen content and storage time on the nutrient composition of biogas slurry were studied,and the influence factors were analyzed.The results showed that:(1)The contents of total nitrogen,available nitrogen and ammonia nitrogen in the biogas slurry were gradually decreased,and the lowest was 285.2 mg/L,273.5 mg/L,202.8 mg/L,respectively,when the biogas slurry was stored at 30? for 60 days.(2)The content of total phosphorus and available phosphorus in biogas slurry decreased gradually.When the temperature was 30 ?,the available phosphorus content was the lowest at 3.5 mg/L for 30 days.(3)The content of total potassium and available potassium in biogas slurry showed a decreasing trend.(4)The nutrient content,temperature and oxygen content of the biogas slurry are the main influencing factors,and the storage time and the lighting condition are the secondary influencing factors.And then fermented with straw and biogas slurry as raw materials,the effect of different TS on the fermentation was studied by fixing heap retting ratio and ratio of raw materials.According to the gas production and the ability of straw to absorb the biogas slurry,the optimum TS range is 10%to 20%.Based on the design principle of Box-Behnken test,the mathematic model of cumulative gas production and TS,compost ratio and raw material ratio was established.By adjusting TS,compost ratio and ratio of raw materials,The preliminary fermentation conditions of straw anaerobic digestion biogas slurry were determined by the effect of gas production.Based on this,the case study was carried out with 1000 m3 biogas project.Through the continuous anaerobic digestion process of straw,Engineering biogas slurry emissions,to determine the straw anaerobic digestion biogas slurry the best parameters of the conditions.The results show that:(1)The correlation coefficient R2 of the regression equation is 0.9684,which is significant at 0.01 level,which indicates that the regression equation and the fitting result are better.(2)The factors affecting the anaerobic digestion of biogas slurry were the ratio of TS>raw material ratio.(3)The initial fermentation process parameters of straw anaerobic digestion biogas slurry were as follows:TS was 19%,raw material ratio(straw:biogas slurry)was 0.88,and the ratio of composting ratio(biogas slurry:straw)for 3.5.(4)For the daily amount of biogas slurry of 1000 m3 biogas project,a continuous straw anaerobic digestion biogas project with a volume of 225m3 and TS of 18.1%could be used for treatment.(5)The optimum fermentation conditions were as follows:TS was 18.1%,raw material ratio(straw:biogas slurry)was 0.88,and the retting ratio(biogas slurry:straw)was 3.50.