Methane gas production in sewers is largely unregulated, however it is:
- A serious Greenhouse gas
- An Explosive risk
- An Occupational Health and Safety Risk
- A high cost when Carbon Taxes are introduced
Methane gas is 21 - 25 times worse as a pollutant than carbon dioxide. Recent research has shown that methane gas is formed in about the same quantities as sulphides in sewers. Reference
In 2006, the US EPA estimated that the Greenhouse gas emissions from wastewater treatment, were 23.9 Tg (Equivalent CO2) = 23.9 million metric tonnes. Reference (Table 2.1 Page 2.4). That is approximately equivalent to the carbon dioxide released from the generaion of 4 780 000 000 000 kWh or 4 780 000 MWh of electricity. That is about the electrical energy requirement to power 0.54 million homes for a year.
In practical terms, the release of 1 kg of methane is roughly the equivalent to the carbon dioxide emissions associated with the generation of 20kWh of electricity. Reference
If carbon taxes associated with methane gas production in Australia are set at $30.00/ tonne, that represents about $0.75 billion additional cost to the Australian wastewater industry/year.
Biosols impact on methane gas production
Biosol products treat the cause of methane gas production in sewers by removing / reducing the biofilm / sediment complexes in sewer pipes where this gas is formed.
Methane gas is generally vented to the air or escapes from sewers around manholes.
Current research shows that up to half the carbon in sewers may be lost to methane gas production. Sewers are a significant cause of greenhouse gas production. Reference
Loss of carbon in sewers to biogas (carbon dioxide & methane) often leads to a shortage of carbon at the treatment plant and the need to supplement carbon, which further adds to cost and greenhouse gas emissions.
Methane gas is a serious greenhouse gas, but also a source of useful energy.
Slowing down microbial activity in the sewer catchment, preserves carbon in the sewer catchment for use at the treatment plant. Recent research in the US by the Water Environment Research Foundation (WERF) has shown that the potential energy in sewage can potentially meet 12% of the nations (US) energy demand. Reference.
Using Biosol products in the sewage catchment, will minimise carbon loss in the sewer catchment and increase the ability to capture and use that carbon as energy source. Currently wastewater treatment plants use an estimated 3% of the total electricity consumption in the US. (See above reference).
Reduce Your Carbon Foot Print.
Biosol products will minimise biogas (methane & carbon dioxide) production in the sewer catchment. This carbon is then available at the treatment plant as a potential energy source for conversion to electricity, biodiesel or it may be added to the gas supply network and thus reduce climate change impacts.
Laboratory research is showing that Biosol products can increase biogas production from biosolids by about 2 - 3 times. This represents an additional significant energy resource once replicated in the field.
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