Utilization of wastewater and wastewater sludge for production of value added products

污水处理厂每天都会产生大量的污泥。污泥处理及其安全处置在世界范围内是一个昂贵且环境敏感的问题。为了从循环经济的角度促进可持续的污泥管理，迫切需要通过从废水污泥中创造增值产品来制定可行的资源管理方案。在这种情况下，我们研究的长期目标是利用废水污泥作为混合微生物群落的来源，同时生产三种产品，即细胞外多糖（EPS，可用作生物絮凝剂），生物塑料（多羟基烷烃酸酯或PHA）和脂质（生产生物柴油），以生产增值产品。最近，我们的研究表明，废水污泥中含有多种可以同时合成这三种产物的微生物。EPS和生物塑料生产微生物丰富。虽然产脂微生物相对较少，但脂质是所有类型污泥微生物细胞膜的组成部分。因此，如果在特定的微生物培养条件下为污泥微生物提供适当的碳源，则可以同时合成这三种产物，同时最大限度地减少其他不需要的微生物的生长（这些微生物不产生这些产物，并且存在于污泥中）

Wastewater treatment plants produce large quantities of sludge every day. Sludge treatment and its safe disposal is an expensive and environmentally sensitive problem worldwide. To promote sustainable sludge management in the perspective of circular economy, there is an urgent need to develop viable options for resource management through the creation of value added products from wastewater sludge. In this context, the long-term goal of our research is to produce value added products using wastewater sludge as a source of mixed microbial community to generate simultaneously three products namely extracellular polysaccharides (EPS that can be used as bioflocculants), bioplastics (Polyhydorxy alkanoates or PHA) and lipids (to produce biodiesel). Recently, our study demonstrated that wastewater sludge contains numerous types of microorganisms that can simultaneously synthesize these three products. The EPS and bioplastics producing microorganisms are in abundance. Whereas lipid producing microbes are present comparatively to a lesser extent, but lipids are an integral part of the cell membrane of all types of sludge microorganisms. Thus, if a proper carbon source is supplied to sludge microorganisms under specific microbial cultivation conditions, these three products can be simultaneously synthesized while minimizing growth of other unwanted microorganisms (that do not generate these products and are present in activated sludge). Therefore, the principal objective of the proposed research is to develop an innovative and economically viable process for the simultaneous production of these products using activated sludge as a source of microorganisms and different waste materials as carbon source. The specific objectives of the present research program include: analysis of the microbial sludge community; determine proper cultivation conditions, optimization of the process parameters to increase the yield of the products; use of different carbon sources and study of their impact on the composition and molecular weight of the products; and development of a suitable method for recovery of the value-added products. The molecular weight of the bioplastics produced is important because that determines the quality of the final marketable products prepared from the bioplastics. The successful completion of the research will allow to develop a novel process of economical production of bioplastics, bioflocculants and lipids concomitantly and it will eventually promote environment friendly, sustainable sludge management and zero waste concept. The new process will obviate the need of expensive fermenters, their sophisticated and expensive operation, and minimize the production cost. Further, this research is very timely and will aid Canadian industry to develop ecofriendly, commercially viable bioplastics, bioflocculant and lipids and thus strengthening Canada`s environmental policy and zero waste concept.