Review on the fate and recovery of cellulose in wastewater treatment

• The cellulose content in wastewater of various countries are summarized and discussed. • The degradation and fate of cellulose in activated sludge system are mapped. • Three kinds of cellulose recovery approaches are summarized and compared. • The mechanisms of oxygen reduction after cellulose recovery are thoroughly discussed. • A source separation-based cellulose recovery protocol are proposed. The wastewater treatment plants are transforming to water resource recovery facilities. The essence behind this transformation is to recover resources from wastewater as much as possible instead of destroying and removal. By far, a wide array of products (energy, fertilizer, etc.) in wastewater and recovery technologies have been identified. However, only a few technologies have been extrapolated into full-scale practices. Herein, cellulose is such a kind of resource originating from toilet paper and its recovery has been implemented and endorsed by research efforts in terms of environmental and economic favourability. This review aims to comprehensively map the technologies of cellulose recovery from wastewater and clarify the associated internal impact and external market potential. First, the source, fate, and transformation of cellulose in a typical WWTP (applying activated sludge) are analyzed to provide a holistic overview of the recovery potential and points. Second, cellulose recovery technologies are reviewed and summarized in a historical timeline with an emphasis on rotating belt filters. Particularly, the impacts of cellulose recovery on wastewater treatment performance and the valorization routes are introduced and discussed comprehensively to make the benefits more explicit. The third section of the review presents a discussion in terms of sustainability and some other factors/routes to manage toilet paper and cellulose. Considering the mature value chain, versatile application routes, and favorable environmental impact, cellulose recovery is highly recommended to be included in wastewater management.