Pollutant evolution mechanism and kinetic modeling of co-combustion of sewage sludge and wheat straw

Solid waste resource recovery represents a key strategy for optimizing energy structures and alleviating fossil fuel dependence. This study systematically investigates pollutant evolution mechanisms and establishes kinetic models for the co-combustion of sewage sludge (SS) and wheat straw (WS). The results reveal that increasing WS blending ratios gradually decreases coke combustion and burnout temperatures while exponentially enhances overall combustion performance. The addition of 30% WS promotes the conversion of CO₂ into carbon-containing intermediates and substantially suppresses NO and SO₂ formation. A differential evolution algorithm-optimized Multiple Distributed Activation Energy Model (M-DAEM) is established for kinetic analysis. The introduction of 30% WS reduces the central activation energy of the third pseudo-component from 235.90 kJ/mol to 181.51 kJ/mol. Overall, 30% WS appears to have a more pronounced effect on overall fuel interaction and activation energy reduction, whereas 70% WS provides the greatest SO₂ emission reduction (58.08%). This work provides a robust theoretical basis for the clean and efficient utilization of solid waste and the synergistic pollutant control of co-combustion systems.