Carbon Emissions from Sludge Treatment in a Sewage Treatment Plant: Field Study Investigation in Guangzhou, China

The treatment of sludge is one of the main sources of carbon emissions throughout the entire life cycle of sewage treatment. This study conducted carbon emission analysis on the sludge treatment process of a sewage treatment plant in Guangzhou, China, and offered a carbon accounting boundary calculation process for the sludge called the deep dehydration–drying–incineration process. An international standard method was improved to offer a carbon emissions accounting method for direct carbon emissions, indirect carbon emissions, and carbon sink for the sludge treatment of the effluent treatment plant. Research has found that the amount of sludge treatment is directly proportional to carbon emissions and carbon sinks. When the sludge treatment capacity reaches 600 t or more, almost zero carbon emissions are achieved, and the carbon emissions generated during the incineration stage of sludge treatment are the highest in all process steps. In addition, there is a significant positive correlation between dry sludge treatment capacity and carbon emissions from drying/integration. There is a significant positive correlation between dry sludge treatment capacity and direct emissions caused by incineration, but there is no correlation with carbon emissions generated by the use of electricity/chemicals. This study offered important data support and technical reference for the resource development and low-carbon disposal regulation of sludge, and a basis for the calculation of carbon emissions throughout the entire process of sludge treatment.