Advanced Water Management Centre, Gehrmann Building, The University of Queensland, Brisbane, Queensland 4072, Australia.
Paques BV, Tjalke de Boerstritte 24, 8561 EL, Balk, Netherlands.
Water Res. 2021 Feb 15;190:116760. doi: 10.1016/j.watres.2020.116760. Epub 2020 Dec 17.
The application of granular biomass has enabled energy efficient, high-rate wastewater treatment systems. While initially designed for high-strength wastewater treatment, granular systems can also play a major role in resource recovery. This study focused on the formation of purple phototrophic bacteria (PPB) granular biomass during synthetic wastewater treatment. Liquid upflow velocity was applied as the driving force for granulation. Separate reactors were operated at either low (2-5m h) or high (6-9m h) upflow velocities, with sludge retention times (SRTs) ranging from 5-15d. Reactors produced anaerobic, photo-granules within 50d. The sludge volume index (SVI) of the granules was 10mL g and average settling rates were greater than 30m h, both metrics being similar to existing granular technologies. Granule sizes of 2-3mm were recorded, however the particle size distribution was bimodal with a large floc fraction (70-80% volume fraction). The extracellular polymeric substance (EPS) and alginate-like extract (ALE) contents were similar to those in aerobic granular biomass. Fluorescence in-situ hybridisation (FISH) imaging identified PPB bacteria dispersed throughout the granules with very few methanogens and an active core. Outer layer morphology was substantially different in the two reactors. The high-upflow reactor had an outer layer of Chromatiales and an inner layer of Rhodobacteriales, while the low-upflow reactor had lower abundances of both, and limited layering. According to 16s gene sequencing, PPB were a similar fraction of the microbial community in both reactors (40-70%), but the high upflow granules were dominated by Chromatiales (supporting FISH results), while the low upflow velocity reactor had a more diverse PPB community. Methanogens were seen only in the low upflow granules and only in small amounts (≤8%). Granule crude protein content was ~0.60gCP gVS (0.45gCP gTS), similar to that from other PPB production technologies. The growth of a rapid settling and discrete PPB granular biomass on synthetic wastewater suggests methods for resource recovery using PPB can be diversified to also include granular biomass.
颗粒生物质的应用使高效、高负荷的废水处理系统成为可能。虽然最初设计用于高强度废水处理，但颗粒系统也可以在资源回收方面发挥重要作用。本研究重点研究了合成废水中紫色光合细菌（PPB）颗粒生物质的形成。液体上向流速被用作成粒的驱动力。分别在低（2-5m h）或高（6-9m h）上向流速下运行单独的反应器，污泥停留时间（SRT）范围为 5-15d。反应器在50d 内产生厌氧、光合颗粒。颗粒的污泥体积指数（SVI）为 10mL g，平均沉降速率大于 30m h，这两个指标与现有的颗粒技术相似。记录到的颗粒粒径为 2-3mm，但粒径分布呈双峰分布，大絮体分数（70-80%体积分数）。细胞外聚合物（EPS）和类似海藻酸盐的提取物（ALE）含量与好氧颗粒生物质相似。荧光原位杂交（FISH）成像鉴定出 PPB 细菌分散在整个颗粒中，甲烷菌很少，活性核心。两个反应器的外层形态有很大的不同。高上流反应器的外层是 Chromatiales，内层是 Rhodobacteriales，而低上流反应器的这两种物质丰度都较低，且分层有限。根据 16s 基因测序，PPB 是两个反应器中微生物群落的相似部分（40-70%），但上流颗粒的 Chromatiales 占主导地位（支持 FISH 结果），而低上流速度反应器的 PPB 群落则更为多样化。甲烷菌仅在低上流颗粒中且数量较少（≤8%）中可见。颗粒粗蛋白含量约为 0.60gCP gVS（0.45gCP gTS），与其他 PPB 生产技术相似。在合成废水中快速沉降和离散的 PPB 颗粒生物质的生长表明，利用 PPB 进行资源回收的方法可以多样化，也可以包括颗粒生物质。
