Department of Aquatic Ecology, Netherlands Institute of Ecology (NIOO-KNAW), Droevendaalsesteeg 10, 6708 PB, Wageningen, The Netherlands; Bioprocess Engineering, AlgaePARC Wageningen University, P.O. Box 16, 6700 AA, Wageningen, The Netherlands.
Department of Aquatic Ecology, Netherlands Institute of Ecology (NIOO-KNAW), Droevendaalsesteeg 10, 6708 PB, Wageningen, The Netherlands.
Water Res. 2023 May 15;235:119748. doi: 10.1016/j.watres.2023.119748. Epub 2023 Feb 15.
Photogranules are a novel wastewater treatment technology that can utilize the sun's energy to treat water with lower energy input and have great potential for nutrient recovery applications. They have been proven to efficiently remove nitrogen and carbon but show lower conversion rates for phosphorus compared to established treatment systems, such as aerobic granular sludge. In this study, we successfully introduced polyphosphate accumulating organisms (PAOs) to an established photogranular culture. We operated photobioreactors in sequencing batch mode with six cycles per day and alternating anaerobic (dark) and aerobic (light) phases. We were able to increase phosphorus removal/recovery by 6 times from 5.4 to 30 mg/L/d while maintaining similar nitrogen and carbon removal compared to photogranules without PAOs. To maintain PAOs activity, alternating anaerobic feast and aerobic famine conditions were required. In future applications, where aerobic conditions are dependent on in-situ oxygenation via photosynthesis, the process will rely on sunlight availability. Therefore, we investigated the feasibility of the process under diurnal cycles with a 12-h anaerobic phase during nighttime and six short cycles during the 12 h daytime. The 12-h anaerobic phase had no adverse effect on the PAOs and phototrophs. Due to the extension of one anaerobic phase to 12 h the six aerobic phases were shortened by 47% and consequently decreased the light hours per day. This resulted in a decrease of phototrophs, which reduced nitrogen removal and biomass productivity up to 30%. Finally, we discuss and suggest strategies to apply PAO-enriched photogranules at large-scale.
光颗粒是一种新型的废水处理技术，它可以利用太阳能以较低的能量输入处理水，并且在营养物质回收应用方面具有很大的潜力。已经证明，它们可以有效地去除氮和碳，但与好氧颗粒污泥等已建立的处理系统相比，磷的转化效率较低。在本研究中，我们成功地将聚磷菌（PAO）引入到已建立的光颗粒培养物中。我们以每天 6 个周期的顺序分批运行光生物反应器，并交替进行厌氧（黑暗）和有氧（光照）阶段。我们能够将磷的去除/回收从 5.4 增加到 30mg/L/d，同时与不含 PAO 的光颗粒相比，保持类似的氮和碳去除率。为了维持 PAO 的活性，需要交替进行厌氧饱食和有氧饥饿条件。在未来的应用中，有氧条件依赖于光合作用的原位增氧，该过程将依赖于阳光的可用性。因此，我们研究了在昼夜循环下该过程的可行性，在夜间有 12 小时的厌氧期，白天有 6 个短周期。12 小时的厌氧期对 PAO 和光养生物没有不利影响。由于将一个厌氧期延长至 12 小时，六个有氧期缩短了 47%，从而减少了每天的光照时间。这导致光养生物减少，从而将氮去除率和生物量生产力降低了 30%。最后，我们讨论并提出了在大规模应用中富集 PAO 的光颗粒的策略。
