By Andrew Springer, Principal Wastewater Treatment Engineer
Global warming is now recognised as occurring and will lead to rising sea levels, changes in weather patterns, more extreme weather events, with potential for droughts, floods and other devastating impacts. Already New Zealand is committed to carbon reduction through the Kyoto agreement and Paris accord, which has resulted in a 2008 carbon trading scheme but levels of emission are increasing. The Climate Change Response (Zero Carbon) Amendment Bill is proposed as a framework for further legislation to drive a change in the thinking and economy of New Zealand and is setting a target of net zero emissions.
Emissions from wastewater treatment plants are greater than water plants due to the high energy requirement for transport and treatment and the emissions of methane and nitrous oxide because of biological activity making up to 33% of all Water Industry emissions. With a Global Warming Potential of 84 x and 284 x carbon dioxide, small quantities of these persistent gases will have a large impact on our carbon footprint.
By understanding the sources of the emissions and how to compare technologies based on carbon footprint combined with reduction in energy, alternative energy sources and reduction in materials in construction the New Zealand Water Industry will be equipped to contribute to our targets.