批式与连续两相发酵的果蔬废弃物厌氧产气性能

该研究采用批式试验与连续发酵试验探讨了苹果与蔬菜废物的厌氧发酵产气性能,结果表明:38℃下苹果与蔬菜废物混合进行厌氧发酵发生了协同促进作用,显著提高了混合原料的产气能力。在苹果废物与蔬菜废物的混合比例F:V=4:1时,混合原料的产沼气潜力达到了914.6 L/kg。利用修正的Gompertz模型能够很好的模拟果蔬废物批式厌氧发酵产气的累积产气过程,拟合结果的R2在0.983~0.999之间。果蔬废物连续进出料产气过程研究结果表明在HRT=24 d、35℃中温发酵条件下,果蔬废物为原料的一体化两相(combined two phase,CTP)反应器有机负荷OLR可达2.5 g/(L·d)时,此时CTP反应器的产气量最高可达12.9 L/d,反应器内物料比产气量为390 L/kg。这表明CTP反应器可以作为果蔬厌氧发酵产气的反应器。与全混式反应器相比,CTP反应器结构简单、成本低,但对果蔬废物的发酵效率低于全混式反应器。

Biogas production of fruit and vegetable wastes two-phase fermentation by batch and continuous feeding

This study evaluated the biogas production of apple fruit wastes and vegetable wastes using batch test and continuous fermentation test. The biogas production of the mixtures of fruit wastes and vegetable waste with different mixing ratios (Fruit: Vegetable, F:V) was also evaluated. For the batch tests, the F:V was set as 5:0, 4:1, 1:1, 1:4, 0:5, respectively. The batch tests were employed for the evaluation of the biogas production process and the accumulated biogas production of these wastes, which were conducted with 500 mL digesters. During these tests, daily biogas productions were recorded. The results showed that the biogas production values of the mixture of vegetable and apple waste were significantly higher than those of fruit waste or vegetable wastes digested singly at 38℃, which suggested that synergistic effects occurred during the anaerobic digestion of the vegetable wastes mixed with fruit wastes. When the F:V was 4:1, the biogas production of the mixture of fruit wastes and vegetable wastes reached 914.6 L/kg, which was the highest among all the 5 tests. The modified Gompertz model had been proved well for fitting the accumulated biogas production curves of batch digestion of wastes. In this study, the modified Gompertz model was employed to fit the accumulated biogas production curves of the vegetable wastes, fruit wastes and their mixtures. TheR2 values of the fitting curves ranged from 0.983 to 0.999, which was similar with the results of the literatures. This meant that the modified Gompertz model fitted the accumulated biogas production curves of fruit and vegetable wastes well. The continuous tests were conducted with the combined two-phase (CTP) reactors at 38℃, and the F:V values were 4:1 and 1:4, respectively. The hydraulic retention time (HRT) of the reactors was controlled in 24 d by adjusting the reflux of biogas slurry to the reactors. In general, the daily reflux of biogas slurry was about 400 mL. The organic loading rate (OLR) of the CTP reactors was 0.5 g/(L·d) during the first 18 days, and it rose to 1.5 and 2.5 g/(L·d) during the next days. The results showed that the OLR of CTP could reach 2.5 g/(L·d) when treating fruit wastes and vegetable wastes. Under this OLR, the daily biogas production and specific biogas production respectively reached 12.9 and 0.39 L/g. These results showed that the CTP reactor could be employed to treat fruit and vegetable waste for biogas production. However, the digestion rate of fruit and vegetable waste in CTP reactor was lower than continuous stirred-tank reactor, though the CTP reactor had simple structure and low cost.