Department of Biotechnology, University of Verona, Verona, Italy.
Department of Materials, Environmental and City Planning Science and Engineering, Faculty of Engineering, Polytechnic University of Marche, Ancona, Italy.
Water Res. 2020 May 1;174:115633. doi: 10.1016/j.watres.2020.115633. Epub 2020 Feb 20.
This study combined at pilot scale the recovery of cellulosic primary sludge from the sieving of municipal wastewater followed by the production of bio-based VFAs through acidogenic fermentation. The sieving of municipal wastewater was accomplished by a rotating belt filter which allowed the removal of around 50% of suspended solids when operated at solids loading rates higher than 30-35 kgTSS/m h. The solids recovered by sieving contained around 40% of cellulose, which is a suitable raw material for the production of bio-based VFAs. Initially, fermentation batch tests of cellulosic primary sludge were carried out adjusting the initial pH of the sludge at values of 8, 9, 10 and 11, in order to evaluate the best production yields of bio-based VFAs and their composition. The highest VFAs yield achieved was 521 mgCOD/gVS occurring when pH was adjusted at 9, while propionic acid reached 51% of the total VFAs. Then, the optimal conditions were applied at long term in a sequencing batch fermentation reactor where the highest potential productivity of bio-based VFAs (2.57 kg COD/m d) was obtained by adjusting the pH feeding at 9 and operating with an hydraulic retention time of 6 days under mesophilic conditions. The cost-benefit analyses for the implementation of cellulosic primary sludge recovery was carried out consideringthe anaerobic digestion as reference scenario. The economical assessment showed that the production of bio-based VFAs from cellulosic primary sludge as carbon source and/or as chemical precursors give higher net benefits instead of the only biogas production.
本研究在中试规模上结合了从城市污水筛分中回收纤维素原污泥，然后通过产酸发酵生产基于生物的 VFAs。城市污水的筛分是通过旋转带式过滤器完成的，当固体负荷率高于 30-35 kgTSS/m h 时，该过滤器允许去除约 50%的悬浮固体。筛分回收的固体含有约 40%的纤维素，这是生产基于生物的 VFAs 的合适原料。最初，通过调整污泥的初始 pH 值为 8、9、10 和 11，进行了纤维素原污泥的发酵分批试验，以评估基于生物的 VFAs 的最佳生产产率及其组成。在 pH 值调整为 9 时，实现了最高的 VFAs 产率 521 mgCOD/gVS，而丙酸达到了总 VFAs 的 51%。然后，在一个序批式发酵反应器中应用了最佳条件进行长期运行，通过将 pH 值进料调整为 9 并在中温条件下以 6 天的水力停留时间运行，获得了基于生物的 VFAs 的最高潜在生产力（2.57 kg COD/m d）。考虑到厌氧消化作为参考方案，对纤维素原污泥回收的成本效益进行了分析。经济评估表明，从纤维素原污泥作为碳源和/或作为化学前体生产基于生物的 VFAs 比仅生产沼气具有更高的净收益。
