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Using bacteria to clean-up waste

By Tim Sandle     Sep 22, 2014 in Environment
A new method has been devised to use microbes found in pond sediment for cleaning-up waste in rural areas. This is in the form of a “microbe-powered” wastewater treatment system that could help to clean-up large farming operations.
The standard process for treating waste from dairy farms in rural areas is to collect the waste and to place it into a network of ponds, where the waste is treated by bacteria. The downside is that this process generates high levels of carbon dioxide and methane, both of which are atmospheric pollutants.
As an alternative, researchers have created a microbial fuel cell that uses only the power of microbes in the sewage lagoons to generate electricity. In a sense, a “microbial battery.” This fuel cell is a type of bio-electrochemical system that drives a current by using bacteria and mimicking bacterial interactions found in nature.
A microbial fuel cell is made up of an anode and a cathode that are separated by a cation (positively charged ion) membrane. In the anode compartment, fuel is oxidized by microorganisms, generating carbon dioxide electrons and protons. Electrons are transferred to the cathode compartment through an external electric circuit, while protons are transferred to the cathode compartment through the membrane. Electrons and protons are consumed in the cathode compartment. Here they combinine with oxygen to form water.
To develop the model, scientists created favorable conditions for the types of microbes that can naturally generate electrons as part of their metabolic processes; in doing so they consume many of the gases that would ordinarily be released as pollutants. The microbes were able to successfully power aerators in a laboratory study for over a year. Based on this success, the science team aim to test a full-scale pilot.
Whilst urban areas have sophisticated systems in place, the scientists expect their invention to be taken by in rural areas or for it to be used in underdeveloped countries.
The technology was developed by scientists at Washington State University. The findings have been reported to the Journal of Power Sources, in a paper titled “Scale-up of sediment microbial fuel cells.”
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