Impact of Global Warming Concerns on Wastewater Treatment Plant Design and Operation

This paper provides an overview of the impact of global wanning concerns on wastewater treatment plant design and operation. The issues surrounding global wanning concerns are discussed, along with the linkage between global warming and greenhouse gas emissions. US greenhouse gas emission inventories are reviewed, along with the role of wastewater treatment plants in reducing such emissions. It is found that process related emissions from wastewater treatment plants are less than 1% of total greenhouse gas emissions. Limited flexibility exists to reduce process-related emissions. One of the principal options is to minimize CH 4 emissions at the expense of CO 2 emissions by stabilizing biodegradable organic matter aerobically rather than anaerobically, or by capturing and combusting any CH 4 produced. The global warming potential of CH 4 is 21 times higher than that of CO 2 . Principal options for reducing greenhouse gas emissions involve selection of biosolids reuse options and energy consumption measures. Landfilling of waste biosolids should be avoided as this leads to CH 4 emissions. Agricultural reuse can reduce greenhouse gas emissions if land management practices increase soil organic carbon content and/or if crops are grown that can be used to produce renewable fuels (such as ethanol). Greenhouse gas emissions can also be reduced by energy conservation measures that reduce the use of fossil fuels, or the consumption of energy produced from them. Greenhouse gas emissions may be considered during the evaluation of alternatives for upgrading wastewater treatment plants, or as part of an overall emissions inventory.