Department of Chemical Engineering and Analytical Chemistry, University of Barcelona, 08028 Barcelona, Spain.
Water Research Institute, University of Barcelona, 08001 Barcelona, Spain.
Molecules. 2019 Aug 17;24(16):2986. doi: 10.3390/molecules24162986.
Food waste (FW) collected from a university canteen was treated in acidogenic fermenters to produce volatile fatty acids (VFA) under biological pretreatment with mature compost. Batch assays working at pH 6 revealed an increment of 9.0%, 7.9%, and 4.1% (on COD basis) of VFA concentration when adding 2.5%, 3.5%, and 4.5% / of mature compost, respectively, even though the volatile solids (VS) concentration of food waste was lower in the tests with increasing doses of mature compost. For batch tests at pH 7, this VFA generation improvement was lower, even though enhanced COD solubilization was recorded. Operating in semi-continuous conditions at 35 °C, pH of 6, and hydraulic retention time (HRT) of 3.5 days, the addition of 2.5% / of mature compost led to a VFA concentration up to 51.2 ± 12.3% more (on VS basis) when compared to a reference reactor without compost addition. Moreover, the percentage of butyric acid on VS basis in the fermentation broth working at a pH of 6 increased from up to 12.2 ± 1.9% (0% compost addition) to up to 23.5 ± 2.7% (2.5% compost addition). The VFA production was not improved when a higher percentage of mature compost was used (3.5% instead of 2.5% /), and it slightly decreased when mature compost addition was lowered to 1.5% /. When working at a pH of 7 in the semi-continuous fermenters with the addition of 2.5% / mature compost at an HRT of 3.5 days, an improvement of 79% and 104% of the VFA concentration (on VS basis) were recorded as compared to fermenters working at a pH of 6 with 2.5% and 0% / of mature compost addition, respectively. At a pH of 7, higher production of propionic and valeric acids was found with respect to the reactor working at a pH of 6. The effect of pH on VFA generation was estimated to have greater contribution than that of only biological pretreatment using mature compost. At a pH of 7, the VFA yield was higher for the fermenter working with 2.5% / mature compost but at a pH of 7 and HRT of 5 days, the effect of mature compost on VFA production improvement was lower than that obtained at a pH of 6. Moreover, higher solubilization in terms of soluble chemical oxygen demand and total ammonium was detected when biological pretreatment using mature compost was applied at both a pH of 6 and a pH of 7, which indicates enhanced hydrolysis in both conditions.
从大学食堂收集的食物垃圾在成熟堆肥的生物预处理下，在产酸发酵器中被处理以产生挥发性脂肪酸（VFA）。在 pH 值为 6 的分批试验中，分别添加 2.5%、3.5%和 4.5%/的成熟堆肥时，VFA 浓度分别增加了 9.0%、7.9%和 4.1%（基于 COD），尽管随着成熟堆肥剂量的增加，食物垃圾的挥发性固体（VS）浓度降低。对于 pH 值为 7 的分批试验，这种 VFA 生成的改善较低，尽管记录了增强的 COD 溶解。在 35°C、pH 值为 6 和水力停留时间（HRT）为 3.5 天的半连续条件下，添加 2.5%/的成熟堆肥可使发酵液中的 VFA 浓度提高高达 51.2 ± 12.3%（基于 VS），而不含堆肥的参考反应器。此外，在 pH 值为 6 的发酵液中，基于 VS 的丁酸百分比从高达 12.2 ± 1.9%（0%堆肥添加）增加到高达 23.5 ± 2.7%（2.5%堆肥添加）。当使用更高比例的成熟堆肥（3.5%而不是 2.5%/）时，VFA 产量没有提高，当将成熟堆肥添加量降低至 1.5%/时，产量略有下降。当在添加 2.5%/成熟堆肥的半连续发酵器中在 pH 值为 7 并在 HRT 为 3.5 天时工作时，与在 pH 值为 6 并添加 2.5%和 0%/的成熟堆肥时相比，VFA 浓度（基于 VS）分别提高了 79%和 104%。在 pH 值为 7 时，与在 pH 值为 6 的反应器相比，发现丙酸和戊酸的产量更高。VFA 生成受 pH 值的影响大于仅使用成熟堆肥进行生物预处理的影响。在 pH 值为 7 时，对于使用 2.5%/成熟堆肥的发酵罐，VFA 产率较高，但在 pH 值为 7 和 HRT 为 5 天时，成熟堆肥对 VFA 产量提高的影响低于在 pH 值为 6 时获得的影响。此外，在 pH 值为 6 和 pH 值为 7 时，使用成熟堆肥进行生物预处理时，检测到以可溶化学需氧量和总铵表示的更高的溶解，这表明在两种条件下都增强了水解。
