Extraction of nutrients from foam in a membrane activated sludge system

Abstract

This study investigated the feasibility of treating the foams generated in enhanced biological phosphorus removal processes with the microwave‐enhanced advanced oxidation process to reduce solids and solubilize nutrients for recovery purposes. It was found that more than half of the total chemical oxygen demand was solubilized during the treatment with just a small dose of hydrogen peroxide, signifying effective destruction of foam solids. Significant solubilization of phosphates, volatile fatty acids and ammonia was also observed, along with the release of metals contained in the foam, including calcium, potassium, and magnesium, which thereby represents additional potential benefits for nutrient recovery via subsequent crystallization processes. Since the solids content of foam is typically high, pretreatment for thickening sludge solids is not necessary prior to the use of microwave‐enhanced advanced oxidation processes. As a result, this also offers further potential for reduction of energy costs. The process could be an efficient method for the removal and control of foam and the recovery of all available phosphorus at the same time.

Keywords:

• sewage foam
• microwave
• advanced oxidation process
• wastewater
• nutrient recovery

Acknowledgements

The authors wish to acknowledge the research funding provided by the Natural Science and Engineering Research Council (NSERC) of Canada.