Electrochemical process for phosphorus recovery from wastewater treatment plants

Phosphorus (P) is a nonrenewable macronutrient, indispensable for plant growth. There is a critical need to reassess current use of P, recover it from “waste” and reuse it in various applications. This is the basis of preserving P as a valuable resource. It would significantly contribute to resolving the issue of environmental degradation as well as resource scarcity while ensuring global food security.

There are currently various methods of recovering P from waste streams generated on Wastewater Treatment Plants. Taking into consideration that the increased utilization of secondary resources is an important issue in waste strategies of the European Union countries, it makes sense to search for the upgrade of these wastes while recycling P.

The electrokinetic (EK) process can be an effective technique for removing contaminants and recover P from sewage sludge and its ashes. The application of a low-level direct current onto this matrix results in both electroosmotic and electromigration flows, which are able to induce the movement of species. Phosphate can selectively accumulate in the anolyte allowing its recovery. For this, the EK process has been applied to sewage sludge and sewage sludge ashes at laboratory scale. A set of major parameters have been studied: current, pH control, liquid:solid ratio, and cell design. This chapter aims to make an overview of the results achieved so far on the feasibility of the EK process to recover P from sewage sludge and its ashes.