Supporting data for "Production of Polyhydroxyalkanoates (PHAs) from urban food waste with mixed microbial culture"

As urban areas expand and economies advance, municipal solid waste accumulation becomes a pressing concern world wild. Among various urban wastes, food waste (FW) is a major component. The typical Chinese FW is predominantly starch-based, offering rich resources including carbon, nitrogen, and phosphorus. This makes it an optimal candidate for anaerobic fermentation (AF), wherein the wasted carbon is transformed into volatile fatty acids (VFA) and subsequently used to produce PHA. In light of this, this study delves into an innovative biological process that integrates FW fermentation with a PHA mixed microbial culture (MMC) to accomplish waste reduction and simultaneous resource recovery.In the combination of FW fermentation and single-stage PHA MMC, a substantial CODVFA/g VS0 of 0.51 ± 0.07 g was gained with a CODVFA/COD of 0.7 during FW fermentation for effective PHA accumulation. Across a 198-day span, overall 80% CODVFA was removed, and a maximum PHA content rate of 39.1 ± 7.7 g/g VSS with a yield of 0.17 ± 0.06 g/g CODVFA was achieved. An overall yield of 8.0% wt PHA/CODVFA was estimated based on the mass balance calculation. Bioinformatics analysis results revealed that Xanthobacter was the most dedicated contributor to PHA producing with an abundance remaining at almost 60% regardless of changes in carbon source, loading rate, or nutrients amount.Despite FW, the wasted activated sludge (AS) generated by wastewater treatment plants (WWTPs), also constitutes a significant portion of urban waste. The co-fermentation of FW and AS enhanced VFA production, yielding a CODVFA/g VS0 of 0.43 ± 0.06 g and a high CODVFA/COD of 78.5%. Over the 186 days of operation, the PHA MMC achieved a peak PHA% of 40.0 ± 4.2 g/g VSS, with a yield of 0.14 ± 0.07 g/g CODVFA, and an overall PHA yield of 12.5% wt PHA/ CODVFA daily. The incorporation of AS for fermentation notably elevated the proportion of propionate in VFAs, leading to a transition from polyhydroxybutyrate (PHB)-dominant to polyhydroxyvalerate (PHV)-dominant PHA composition. The 16S rRNA analysis revealed the genus Mesorhizobium crucially contributed to PHA generation, maintaining dominance throughout the whole operation period.To address the distinct kinetics for biomass growth and PHA accumulation, and to mitigate the adverse effects of PHA production-related sludge bulking, a novel waste conversion system which comprised of an FW fermenter and a 2-stage PHA MMC was studied. The FW fermentation yielded a CODVFA/g VS0 of 0.53 g and a CODVFA/COD of 73.2%, which served as feedstock for the 2-scale system spanning 120 days. Throughout this period, a PHA accumulation of 46.4% was achieved, with a PHA yield of 0.16, ultimately attaining a maximum daily PHA production yield of 12.1% wt PHA/ CODVFA. 16S rRNA analysis revealed consistent trends in the functional microbial community of the 2-stage MMC that the initially dominated Leucobacter and Xanthobacter were gradually instead of. the coexistence of diverse functional microorganisms. Overall, the findings of this study suggested the combination of FW-based fermentation and PHA MMC holds promise as an appropriate technology for urban waste reduction and resource recovery.

随着城市区域的扩张与经济的进步，城市固体废弃物的累积已成为全球范围内的紧迫问题。在城市废弃物中，食物废弃物（FW）占据了主要成分。典型的中国食物废弃物以淀粉为主，富含碳、氮和磷等资源。这使得其成为厌氧发酵（AF）的理想候选物，在厌氧发酵过程中，废弃的碳被转化为挥发性脂肪酸（VFA），进而用于生产聚羟基脂肪酸（PHA）。鉴于此，本研究深入探讨了将食物废弃物发酵与PHA混合微生物培养（MMC）相结合的创新生物过程，旨在实现废弃物减量化和资源回收。在食物废弃物发酵与单阶段PHA MMC的结合中，发酵过程中获得了0.51 ± 0.07 g的CODVFA/g VS0，CODVFA/COD比为0.7，以实现PHAs的有效积累。在198天的实验周期内，总体去除80%的CODVFA，并实现了39.1 ± 7.7 g/g VSS的最高PHA含量率，CODVFA的产率为0.17 ± 0.06 g/g，基于质量平衡计算，估计总体PHA/CODVFA的产率为8.0% wt。生物信息学分析结果表明，黄杆菌（Xanthobacter）是生产PHA的主要贡献者，其丰度在碳源、加载率或营养物质量的变化下仍保持在近60%。尽管如此，由污水处理厂（WWTPs）产生的废弃活性污泥（AS）也构成了城市废弃物的一个重要部分。食物废弃物与活性污泥的共发酵增强了VFA的产生，CODVFA/g VS0为0.43 ± 0.06 g，CODVFA/COD高达78.5%。在186天的运行过程中，PHA MMC实现了40.0 ± 4.2 g/g VSS的峰值PHA%，CODVFA的产率为0.14 ± 0.07 g/g，日平均PHA产率为12.5% wt PHA/CODVFA。活性污泥的加入显著提高了VFA中丙酸的比例，导致PHA从以聚羟基丁酸（PHB）为主转变为以聚羟基戊酸（PHV）为主的组成。16S rRNA分析显示，放线菌属（Mesorhizobium）对PHA的生成至关重要，在整个运行期间保持主导地位。为了解决生物质生长和PHA积累的动力学差异，以及减轻PHA生产相关污泥膨胀的负面影响，本研究探讨了由食物废弃物发酵器和两阶段PHA MMC组成的创新废物转化系统。食物废弃物发酵产生了0.53 g的CODVFA/g VS0和73.2%的CODVFA/COD，作为两阶段系统的原料，该系统运行了120天。在此期间，实现了46.4%的PHA积累，PHA产率为0.16，最终达到了每日最大12.1% wt PHA/CODVFA的PHAs生产率。16S rRNA分析揭示了在两阶段MMC的功能微生物群落中，最初占主导地位的欧文菌（Leucobacter）和黄杆菌逐渐转变为多种功能微生物的共存。总体而言，本研究的结果表明，基于食物废弃物的发酵与PHA MMC的结合有望成为城市废弃物减量和资源回收的适宜技术。