Resource recovery from biological wastewater treatment system and biosolids

生物废水处理是一种既有成本效益又能去除废水污染物的处理方法。目前，国际水协会认为好氧颗粒污泥（AGS）是世纪最有前途的城市污水生物处理技术之一。好氧颗粒是由不同菌株的微生物在特定操作条件下通过细菌细胞分泌的胞外聚合物（EPS）聚集在一起的密集菌落，其大小范围为0.2 - 5 mm。城市和不同的工业废水已有效地处理使用AGS生物技术。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高EPS含量和颗粒基质中发生的生化反应。目前从AGS反应器的污泥中回收四种高价值产品：磷、聚羟基链烷酸酯、藻酸盐样胞外多糖和色氨酸。最近，在AGS系统的污泥中也鉴定出可得然胶、酪氨酸和苯丙氨酸。黄原胶被广泛用作食品工业的补充剂和石油工业的粘度控制。黄原胶市场于二零二零年估计为987，700，000美元。可得然胶用于食品（增稠剂）、化妆品（保湿剂和熏香剂）和生物医学/制药（抗肿瘤或抗HIV）行业。随着2005年美国食品和药物管理局批准可得然胶用于食品工业，市场对可得然胶的需求不断增长。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，是生产人造甜味剂甜菊糖的基本原料，并在农业中用于收获后的保存。迄今为止，尚未探索从AGS系统产生的污泥中回收黄原胶、可得胶、酪氨酸和苯丙氨酸。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，并且鉴于黄原胶，可得然胶，酪氨酸和苯丙氨酸的高市场需求，拟议的研究旨在优化其在好氧颗粒基质中的生产，同时保持废水处理。还将制定适用于每种资源的污泥有效提取方案和回收方案。这项研究的成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一个新市场，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的道路，并促进经济繁荣。此外，高素质的人员也将在加拿大劳动力研究计划中接受全面培训。

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.