Energy from wastewater   

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[edit] Wastewater in an energy resource

The treatment of wastewater using conventional methods consumes significant amounts of energy.^[1]

However, wastewater actually contains biochemical energy, which is normally thrown away, or worse, discarded as pollution. Biochemical oxygen demand^W is a measure of pollution, but also indicates the energy content of the wastewater.

[edit] Methods of extracting energy

Biogas is one method with the potential for use as an appropriate technology.

Various waste-to-energy^W technologies including incineration^W can be used to dispose of solid waste. This includes dried sewage sludge.^W

Microbial fuel cells^W are a completely new method of energy recovery, and are currently under development. They could be used to produce electricity; also they could produce hydrogen - the BioElectrochemically Assisted Microbial Reactor (BEAMR) method is claimed to yields four times the hydrogen of fermentation alone.^[2]

[edit] Footnotes

1. ↑ According to one estimate, "In the USA... 5% of electricity we produce is used to treat water and wastewater." - from Microbial Fuel Cells, B.E. Logan, 2005. Does this include the cost of contructing colleciton and treatment facilities, including the embedded energy^W in the materials?^{[Suggested project]}
2. ↑ 2005 Popular Mechanics Breakthrough Awards (published in the November 2005 issue). According to this update (Nov 2007) efficiency has reached 82%. For more information, see Microbial Fuel Cells, by Bruce Logan of Penn State University (2005), who won a 2005 Popular Mechanics Breakthrough Award.[1]