The Carbon Footprints of Various Biosolids Treatment Processes

Introduction

A wide variety of processes are capable of treating biosolids to comply with pathogen reduction requirements as defined by 40 CFR 503 regulations. However, within Europe, long-term sustainability and carbon impacts are becoming more influential, including economic incentives in the form of taxes and levies to prevent the release of greenhouse gases (GHGs). GHGs have been classified by the Intergovernmental Panel on Climate Change to include, among others, carbon dioxide, methane, nitrous oxide, tetraflouromethane, sulfur hexafluoride, hydrofluorocarbons, and chlorofluorocarbons.

There is an implicit link between power consumption and a carbon footprint; consequently, the power sector is responsible for 37% of all anthropogenic carbon dioxide. In the United Kingdom, the water industry accounts for 3% of all power consumed. Most of this power is used to run processes and pump water. Determining a carbon footprint involves measuring the GHGs emitted during a process and converting the data to a carbon dioxide equivalent. For example, the equivalent for methane is 21, implying that 1 unit of methane has the same global warming potential as 21 units of carbon dioxide.

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