Australian Centre for Water and Environmental Biotechnology, The University of Queensland, Brisbane, QLD 4072, Australia.
Eidgenössische Technische Hochschule Zürich (ETH), Zürich 8092, Switzerland.
Water Res. 2022 Jun 1;216:118327. doi: 10.1016/j.watres.2022.118327. Epub 2022 Mar 19.
To make purple phototrophic bacteria (PPB)-based technologies a reality for resource recovery, research must be demonstrated outdoors, using scaled reactors. In this study, a 10 m long PPB-enriched flat plate photobioreactor (FPPBR) with a volume of 0.95 m was operated for 253 days, fed with poultry processing wastewater. Different operational strategies were tested, including varying influent types, retention times, feeding strategies, and anaerobic/aerobic conditions in a novel mixed metabolic mode concept. The overall results show that regardless of the fermented wastewater fed (raw or after solid removal via dissolved air flotation) and the varying environmental conditions (e.g., light exposure and temperatures), the FPPBR provided effective volatile fatty acids (VFAs), N, and P removals (average efficiencies of >90%, 34-77%, and 28-45%, respectively). The removal of N and P was limited by the availability of biodegradable COD. Biomass (C, N and P) could be harvested at ∼90% VS/TS ratio, 58% crude protein content and a suitable amino acid profile for potential feed applications. During fully anaerobic operation with semicontinuous/day-only feeding, the FPPBR showed biomass productivities between 25 and 84 g VS m d (high due to solid influx; the productivities estimated from COD removal rates were 6.0-24 g VS•m•d (conservative values)), and soluble COD removal rates of up to 1.0 g•L•d (overall average of 0.34 ± 0.16 g•L•d). Under these conditions, the relative abundance of PPB in the harvested biomass was up to 56%. A minimum overall HRT of 2-2.4 d (1.0-1.2 d when only fed during the day) is recommended to avoid PPB washout, assuming no biomass retention. A combined daily-illuminated-anaerobic/night-aerobic operation (supplying air during night-time) exploiting photoheterotrophy during the day and aerobic chemoheterotrophy of the same bacteria at night improved the overall removal performance, avoiding VFA accumulation during the night. However, while enabling enhanced treatment, this resulted in a lower relative abundance of PPB and reduced biomass productivities, highlighting the need to balance resource recovery and treatment goals.
为了使基于紫色光合细菌（PPB）的技术成为现实，用于资源回收，必须在户外使用规模化反应器进行研究。在这项研究中，使用 10 米长、体积为 0.95 立方米的富 PPB 平板光生物反应器（FPPBR）进行了 253 天的运行，使用家禽加工废水作为进料。测试了不同的操作策略，包括在新型混合代谢模式概念中改变进水类型、停留时间、进料策略和厌氧/好氧条件。总体结果表明，无论进料是发酵废水（经过气浮去除固体后的原水或经过气浮去除固体后的发酵废水）还是环境条件（例如光照和温度）如何变化，FPPBR 都能有效地去除挥发性脂肪酸（VFAs）、N 和 P（平均去除效率分别大于 90%、34-77%和 28-45%）。N 和 P 的去除受到可生物降解 COD 的可用性的限制。生物量（C、N 和 P）可以以约 90%VS/TS 的比例、58%粗蛋白含量和适合饲料应用的合适氨基酸谱进行收获。在半连续/仅白天进料的完全厌氧运行中，FPPBR 的生物量生产力在 25 到 84gVSm d 之间（由于固体流入量高；从 COD 去除率估计的生产力为 6.0-24gVS•m•d（保守值）），并且可溶性 COD 去除率高达 1.0gL d（总体平均值为 0.34±0.16gL d）。在这些条件下，收获生物量中 PPB 的相对丰度高达 56%。建议最小总 HRT 为 2-2.4d（仅在白天进料时为 1.0-1.2d），以避免 PPB 冲洗，假设没有生物量保留。白天利用混合营养型光合异养作用和夜间同一种细菌的好氧化能异养作用的结合式白天光照-厌氧/夜间好氧操作（夜间供气）提高了整体去除性能，避免了夜间 VFA 积累。然而，虽然能够增强处理效果，但这导致 PPB 的相对丰度降低，生物量生产力降低，突出了需要平衡资源回收和处理目标。
