Studies On Anaerobic Digestion Engineering Parameter Of Rice Straw

Conversion of crop stalks into renewable energy through various technologies is one of effective methods to reduce environmental pollution and develop new energy resources. Anaerobic biogasification of rice straw plays an important role in rural energy development in China. Taking the centralized gas supply station of anaerobic biogasification of rice straw of Ting Xiang Village, Zhixi town,Jintan city, Jiangsu Province as a platform, this paper conducted two batch the effects of different additives on anaerobic digestion of rice straw; In the room, different C/N on anaerobic digestion of rice straw and composting of the biogas residue of rice straw was conducted, which can provide a theoretical basis for the high-efficient energy conversion of rice straw,can make the improvement of biogas production, abd can be an application of biogas residues and the engineering operation of anaerobic biogasification of rice straw.On station of anaerobic biogasification of rice straw of Ting Xiang Village, Zhixi town,Jintan city, Jiangsu Province, first experiment set three additives anaerobic digestion of rice straw, which are rice straw+partner(including some inorganic salts manufactured by Institute of Agricultural Resources and Environment, Jiangsu Academy of Agricultural Sciences), rice straw+pig manure and rice straw+human excrement, respectively. Results showed that:(1) The effect of backwash is not obvious;(2) The gas production per gram TS is very low(about0.2-0.3m/kgTS);(3) The floating height of rice straw is high(about45-65cm);(4) Water removing device and flow meter device were put in the reverse order.To solve this problem, we conducted a second batch experiment:rice straw+pig manure, rice straw(pulverized)+partner and rice straw+partner. Results showed that pulverization pretreatment of rice straw made a significant enhancement to the biogas production; after deducting the gas production from anaerobic digestion of pig manure, gas production of rice straw+pig manure is lower than rice straw (pulverized)+pig manure Although rice straw(pulverized)+partner improved gas production,it cost much electric power and manpower.For further analysis of the effect of backwash, in order to improve the effect of backwash, in the end of the first batch fermentation, taking the biogas residue of rice straw of different depth and different locations with the same depth as a sample, this paper conducted biogas fermentation potential of the biogas residue of rice straw. Results showed that the biogas production of different profiles is different, the upper>the middle>the lower; closer to overflow, biogas fermentation is lower.Person daily gas consumption is increasing with the increase of the number of households’population. A family of one average per capita is0.502m3; a family of two averages per capita is0.233m3; a family of five averages per capita is0.188m3.Effect of C/N on anaerobic digestion process of rice straw and nitrogen transformation during anaerobic digestion of rice straw were studied. Four treatments with the initial C/N ratio of15:1(T1),25:1(T2),35:1(T3) and45:1(T4) were designed. The results indicated that, biogas production of rice straw was influenced significantly by initial C/N ratio; too higher initial C/N ratio was adverse to biogas production; the highest TS biogas yield of286.82mL/g was obtained at initial C/N ratio of15:1. Average methane content of all treatments was about55percent. After anaerobic digestion, much organic matter and crystalline of cellulose of rice straw were decomposed and content of volatile solid, cellulose and hemi-cellulose were decreased largely and content of lignin was increased slightly, which was consistent to the results of physic-chemical analysis. Much nitrogen was lost during anaerobic digestion and nitrogen loss rate of T1, T2, T3and T4were43.97%,42.94%,33.71%and32.34%, respectively. After anaerobic digestion, much nitrogen was put into anaerobic slurry, but amount of nitrogen in fermentation residue increased from29.77%to42.86%with the initial C/N ratio increased from15:1to45:1. The major nitrogen forms in anaerobic system was ammonium nitrogen and organic nitrogen, and the rate of ammonium nitrogen to total nitrogen decreased and the rate of organic nitrogen to total nitrogen increased with the increasing initial C/N ratio. Content of nitrate in anaerobic system was low.Composting of the biogas residue of rice straw showed that volatile solids, TOC and pH continued to decline. TN andNH4+-N increased after the first drop. Compared with rice straw (The whole plant)+partner, rice straw(pulverized)+partner got maturity more quickly. The appearance coincides with they biogas production.