Analysis of carbon emissions of sludge co-incineration with urban organic solid waste

Sludge drying incineration has become one of the mainstream treatment technologies. With the promotion of the construction of zero-waste city， urban solid waste treatment and disposal is becoming increasingly prominent. Sludge co-incineration with urban organic solid waste is a feasible model to achieve energy self-supply and near-zero carbon emission of sludge incineration system， which is conducive to reducing pollution， carbon emission， energy saving and high-efficiency of sludge treatment. This research focuses on common industrial solid wastes， drawing from engineering practices， examines the energy balance and carbon emissions of the co-incineration of these wastes with sludge. The calculation results indicate that urban organic solid waste synergy can increase the average heat value of the mixed fuel fed into the incinerator， and make the system achieve energy surplus， can not only meet the system's own heat demand such as sludge drying， without consuming external supplementary heat sources and electrical energy， but also achieve cogeneration of heat and power. Compared to sludge incineration， co-incineration with urban organic solid waste increases the direct carbon emission intensity； however， with self-sufficiency in energy， the indirect carbon emission intensity caused by external heat and electricity consumption is significantly reduced. Additionally， the external supply of energy and resources leads to carbon offset， and the net carbon emission of the system may potentially contribute to carbon sequestration， also known as carbon sinks. When the proportion of fossil derived carbon in urban organic solid waste reaches 50%， the carbon sink intensity per unit processing capacity is -28.5 kg/t.