Domestic Wastewater Treatment as a Net Energy Producer–Can This be Achieved?

TLDR

Wastewater is increasingly viewed as a resource for water, plant nutrients, and energy rather than a waste product. The article investigates how wastewater’s organic and thermal content can be harnessed for energy, aiming to transform treatment into a net energy generator. Potential methods include microbial fuel cells that directly convert organic matter to electricity and membrane processes combined with complete anaerobic treatment to produce biogas. Using wastewater nitrogen and phosphorus for fertilization can offset synthetic fertilizer energy costs, while microbial fuel cells show promise but require improvements to compete with biogas production.

Abstract

In seeking greater sustainability in water resources management, wastewater is now being considered more as a resource than as a waste-a resource for water, for plant nutrients, and for energy. Energy, the primary focus of this article, can be obtained from wastewater's organic as well as from its thermal content. Also, using wastewater's nitrogen and P nutrients for plant fertilization, rather than wasting them, helps offset the high energy cost of producing synthetic fertilizers. Microbial fuel cells offer potential for direct biological conversion of wastewater's organic materials into electricity, although significant improvements are needed for this process to be competitive with anaerobic biological conversion of wastewater organics into biogas, a renewable fuel used in electricity generation. Newer membrane processes coupled with complete anaerobic treatment of wastewater offer the potential for wastewater treatment to become a net generator of energy, rather than the large energy consumer that it is today.