高固体含量进料提高餐厨废弃物连续厌氧发酵性能

为了考察高低2种进料固体含量在餐厨废弃物中温厌氧发酵中对产气效果的影响,该文将餐厨废弃物预先配制成固体质量分数为19.0%和9.5%的2种进料,应用单相连续厌氧发酵系统并设置低、中、高3个有机负荷,考察产气效率及厌氧反应器内部固体含量、氨氮浓度和p H值的变化情况。试验结果表明,高固体含量进料组的挥发性固体产气率在3个机负荷下均明显占优,分别为634.34、623.14和550.08 m L/g,而低固体含量进料组分别为549.86、491.22和0 m L/g。此外,采用高固体含量进料的厌氧反应器内固体质量分数一直保持在10%以下,符合湿法半连续发酵工艺要求。该研究对餐厨废弃物湿法厌氧发酵的沼气生产中,如何最大化节约原料稀释用水上提供了设计参考。

High solid concentration feedstock improving performance of continuous anaerobic digestion of food waste

Abstract: The effect of feedstock solids concentration on the performance of mesophilic anaerobic digestion of food waste (FW) was investigated in this assay using single wet continuous experiments. FW was made into two kinds of feedstocks, one has a high solids concentration of 19.0% and the other has a low solids concentration of 9.5%. The effects of the two different solids concentrations of feedstocks on the mesophilic anaerobic digestion of FW for biogas production were compared. A total of six digesters were designed in present assay, and were equally divided into two groups. One group was fed with high solids concentration of feedstock, and the other group was fed with low solids concentration of feedstock. The three digesters of each group were operated under three different organic loading rates (OLR) of 1.78, 2.54, and 3.56 g/(L·d), respectively. The test lasted for 50 days. The biogas volume, methane content and the pH value of effluent were monitored each two days, and the total solids (TS), volatile solids (VS), ammonia concentration of the effluent were monitored each week.The results showed that the digesters fed with high solids content feedstock could obtain a higher methane production rate (mL/g-VS) than those fed with low solids content feedstock in the same OLR, the pH of all the high solids feedstock trials had been maintained above 7.20, and the trials of low solids feedstock had been maintained above 7.15 only observed in the former two lower OLRs, the pH of the third digester operate under OLR of 3.56 g/(L·d) decreased to below 6.5 at 10th day leading to biogas production failure. The ammonia concentrations of all digesters had been maintained bellowed the initial inhibition concentration of 2700 mg/L and the toxic concentration of 3000 mg/L reported by previous literatures. In addition, the interior TS concentration of each digester fed with high solids content feedstock was lower than 10% which agreed with the request of wet anaerobic digestion.All the findings of this assay suggested that the digesters applied high solids contend feedstock could obtain a better performance of biogas production than the group adopted low solids contend feedstock. There are three conclusions could be summarized as follows: 1) Under the same OLR, the high solids group could obtain higher methane production rate and volumetric biogas production rate than the low solids group; 2) Under the same OLR, the TS concentrations in the interior of the high solids group were obviously higher than the other group, which was helpful to maintain a higher cell content in the digester; 3) Under the same OLR, the process of anaerobic digestion using high solids feedstock not only can save the dilution water used to decrease the solids concentration of raw materials but also can reduce the discharge of biogas effluent, which could decrease the comprehensive cost of biogas production. This study provided technical reference for the design of actual biogas engineering on the aspect of how to dilute the raw FW and furthest save the dilution water.