Resource recovery from biological wastewater treatment system and biosolids

生物废水处理是去除废水污染物的一种公认的经济有效的处理方案。目前，国际水协认为好氧颗粒污泥(AGS)是21世纪最有前途的城市污水生物处理技术之一。好氧颗粒污泥是细菌细胞在特定的运行条件下分泌的胞外聚合物(EPS)，是由不同菌株组成的致密菌群，大小在0.2-5 mm之间。利用AGS生物技术有效地处理了城市和不同的工业废水。除了高效的废水处理，AGS还提供了从废水中回收高价值产品的机会。这是由于颗粒基质中的EPS含量很高，以及颗粒基质中发生的生化反应所致。目前从AGS反应器的污泥中回收四种高价值产品：磷、聚羟基烷酸酯、类海藻酸胞外多糖和色氨酸。最近，在AGS系统的污泥中也发现了柯德兰、酪氨酸和苯丙氨酸。黄原胶广泛应用于食品工业的补充剂和石油工业的粘度控制。2020年，黄原胶的市场规模估计为9.877亿美元。可得兰用于食品(增稠剂)、化妆品(保湿增湿剂和熏香剂)以及生物医药/制药(抗肿瘤或抗艾滋病毒)行业。随着2005年美国食品和药物管理局批准可得兰用于食品工业，可得兰的市场需求不断增长。酪氨酸被用作食品补充剂和药品生产。苯丙氨酸被用作饲料和食品补充剂，是生产人工甜味剂阿斯巴甜的基石，并用于农业采后保鲜。到目前为止，还没有从AGS系统产生的污泥中回收黄原胶、柯德兰、酪氨酸和苯丙氨酸的方法。由于污泥中的EPS是天然存在的，是一种生态友好的替代材料，鉴于市场对黄原胶、柯德兰、酪氨酸和苯丙氨酸的高需求，本研究旨在优化其在好氧颗粒基质中的生产，同时保持对废水的处理。还将制定有效的污泥提取方案和适用于每种资源的回收方案。这项研究的结果有可能促进加拿大的经济利益。资源回收将为经济成功开辟新的市场，并为当地废水管理行业创造竞争优势。从AGS系统产生的污泥中回收资源将引领实现循环经济，促进经济繁荣。此外，高素质的人员还将接受针对加拿大劳动力的研究计划的全面培训。

Biological wastewater treatment is an established cost-effective treatment option to remove wastewater pollutants. Currently, the International Water Association considers aerobic granular sludge (AGS) as one of the most promising biological municipal wastewater treatment technologies of the 21st century. Aerobic granules, with a size range of 0.2-5 mm, are a dense colony of different strains of microorganisms held together by extracellular polymeric substances (EPS) secreted by the bacterial cells under special operational conditions. Both municipal and different industrial wastewaters have been effectively treated using AGS biotechnology. In addition to efficient wastewater treatment, AGS offers the opportunity to recover high-value products from the wastewater. This is due to the high EPS content in the granule matrix and the biochemical reactions that take place in the granule matrix. Four high-value products are presently recovered from sludge from AGS reactors: phosphorus, polyhydroxyalkanoates, alginate-like exopolysaccharides, and tryptophan. Recently, curdlan, tyrosine and phenylalanine have also been identified in the sludge from AGS systems. Xanthan is widely applied as a supplement in the food industry and for viscosity control in the oil industry. The xanthan gum market was estimated at US$987.7 million in 2020. Curdlan is used in the food (thickening agent), cosmetic (moisturizing increase, and incense agents), and biomedical/pharmaceutical (antitumor or anti-HIV) industries. With the approval of curdlan by the US Food and Drug Administration for use in the food industry in 2005, there is a growing market demand for curdlan. Tyrosine is used as a food supplement and in the production of medicines. Phenylalanine is used as a feed and food supplement, a building block for the production of the artificial sweetener aspartame, and in agriculture for postharvest preservation. To date, the recovery of xanthan, curdlan, tyrosine, and phenylalanine from the sludge generated by AGS systems has not been explored. Since the EPS in the sludge is naturally occurring and an eco-friendly alternative material, and in view of the high market demand for xanthan, curdlan, tyrosine, and phenylalanine, the proposed research aims at optimizing their production in the matrix of aerobic granules while maintaining wastewater treatment. Effective extraction protocols from sludge and recovery protocols applicable to each of these resources will also be developed. The outcomes of this research have the potential to advance Canada's economic interests. Resource recovery will open a new market for economic success and create a competitive advantage for local wastewater management industries. Resource recovery from the sludge produced by AGS systems will lead the way to attaining a circular economy, and enhancing economic prosperity. Additionally, highly qualified personnel will also be thoroughly trained in the research program for the Canadian workforce.