What evidence exists on ecotechnologies for recycling carbon and nutrients from domestic wastewater? A systematic map

The ecological status of the Baltic Sea is poor and affected by eutrophication, a process which also impacts many other water bodies and is partly the result of point-source emissions of nutrients and carbon from wastewater. At the same time, nitrogen and phosphorus planetary boundaries have been breached.

The primary cause of eutrophication is increased loading of inorganic nutrients and organic matter from terrestrial sources which increases primary production, mainly as algal growth. Because the Baltic Sea has a large catchment in relation to its volume of water and a long renewal time, it is particularly vulnerable to waterborne nutrient loadings.

Despite measures to decrease emissions, the spatial extent of open water eutrophication in the Baltic Sea has increased in recent years. There is therefore a need for more efficient resource management, including the recovery and reuse of nutrients and carbon in waste.

The aim of this paper is to collate evidence on ecotechnologies intended for use in the wastewater sector globally to facilitate the recovery or reuse of carbon and/or nutrients. It poses the key question: What ecotechnologies exist in the recent research literature for the recovery or reuse of carbon, phosphorus and nitrogen from municipal and domestic wastewater systems globally?

Based on the study, the paper identifies a number of implications for future research and maps out knowledge clusters where there already exists a lot of evidence to be synthesised. The authors’ findings suggest that there is a need for policies encouraging reuse or more research funding to investigate the (efficiency of) reuse of carbon and nutrients from wastewater, including risks and benefits of reuse.