The Study Of Rice Straw Fermentation Conditions Optimization And Water Quality Improvement

In this study, we used rice straw as raw material, and fermented it with microorganisms. The index was the degradation rate of the straw's cellulose and lignin. The purpose was to get the most of water-soluble organic carbon. We optimized the fermentation strains and fermentation process. We than utilized the fermentation products to study the improvement of water quality of aquaculture. The carbon-nitrogen ratio in water was regulated by using fermentation products. The polluted water was improved by flocculation. The main research contents are as follows:(1) The effective degradation of rice straw. (2)The optimization of straw fermentation medium. (3)The optimization of fermentation process. (4)The study of fermentation products' effect on water. The results are as follows:1. We used four kinds of strains which could degrade cellulose effectively to conduct solid fermentation for the rice straw. The index are cellulase activity? the degradation rate of the straw's cellulose and lignin? the content of reducing sugar and soluble carbon in products.2 good fermentation strains could be obtained- White-rot fungi and trichoderma viride. Both of them were Combination cultured and fermented in combination. The best combination way was B4-L4, that is, after that White-rot fungi had been cultured for 4 days, trichoderma viride was than inoculated and co-cultured for 4 days. The ratio of inoculum was 1:1,22.16% of soluble carbon was obtained in this way. The degradation rate of the straw's lignin and cellulose was 31.23% and 33.28% respectively.2. Formulation of the fermentation medium was optimized, the optimal fermentation medium were:rice straw (crushed) 85%, wheat bran10%, soybean meal 3.5%, glucose 2.5%, KH2PO40.3%, MgSO4-7H2O 0.2%.3. utilizing single-factor test and orthogonal design, the optimal fermentative condition was:solid-to-liquid ratio 1:1.4, installed capacity 20g/250mL, inoculum size 14%, fermentation temperature 30 ?4. The rice straw was fermented with the optimum medium and the optimal fermentative condition, the degradation rate of lignin and cellulose was 36.82% and 41.25%, respectively. The soluble organic carbon content of products was 24.65%. Compared to optimization before, the degradation rate of cellulose and lignin was increased by 23.95% and 17.90%, respectively. The content of soluble organic carbon increased by 11.24%.5. By adding 1000mg/L fermented products of rice straw to the aquaculture water, the content of ammonia nitrogen and nitrite in water was reduced effectively, and a large floc the emerged on the seventh day. The test proved that adding the fermentation products of straw to the water is an effective method to improve water quality.