Bacterial sewage treatment

| May 16, 2010 | 1 Comments

New Scientist: A newly-discovered type of bacterium that converts ammonium into nitrogen and methane could drastically reduce the amount of energy needed to process sewage.

Researchers from the Delft University of Technology have developed a technique using this new bacterium that by-passes one of the most energy-intensive processes in sewage treatment. In conventional sewage treatment, bacteria convert solid waste into methane and a liquid waste containing ammonium. This ammonium is then digested by other bacteria that require a constant supply of oxygen, which must be pumped in, consuming megawatts of power.

The new technique cuts out this second stage, as the newly-discovered bacteria process ammonium directly into nitrogen gas and methane gas, the latter of which can be collected and used to generate power. So instead of consuming power, this new treatment process could generate it.

Filed Under: Look to Nature

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  1. This technology aims to achieve two goals: – To make beneficial use of methane gas recovered via methane fermentation from a mixture of sewage sludge and organic waste, such as kitchen refuse, received from local communities, viewing a wastewater treatment plant as a facility for using local biomass; and – To promote carbonization-activation and recycling of fermentation residue, or dewatered sludge. This technology system integrates two processes, which are methane fermentation of sewage sludge-biomass mixture followed by power generation using the resultant biogas and carbonization-activation of fermentation residue. The use of biomass is under assessment in Japan, but progress is slow regarding the use of wet biomass due to its high water content which accounts for a high weight percentage. Methane fermentation is attracting great interest as a low-cost means of recovering energy from wet biomass. However, one drawback of the process is the treatment cost for filtrate from the dewatering machine after fermentation. In this regard, a wastewater treatment plant has large wastewater treatment equipment and consumes electricity generated within the plant, and so is expected to be a useful facility for making use of wet biomass. Moreover, methane gas can be used as supplementary fuel for carbonization or carbonization-activation of residual dewatered sludge to promote recycling without consuming fossil fuel. Furthermore, in the case of receiving kitchen refuse included in general domestic waste, the refuse incineration plant can be downsized when rehabilitated.

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