236 / 2022-02-15 17:14:39

Waste utilization of sewage sludge and red mud based on chemical looping catalytic oxidation

chemical looping catalytic oxidation, sewage sludge, red mud, ventilation air methane, waste utilization.

Energy Science and Technology > 2. Greenhouse Gas Emission Reduction and Utilization

The effective and integrated utilization of multiple waste is an important method to reduce carbon emissions. In this work, we propose a multi-waste utilization method based on chemical looping catalytic oxidation (CLCO) that can simultaneously treat industrial solid waste (red mud) discharged from alumina extraction in the aluminum industry, solid sediment material (sewage sludge) generated from water and wastewater treatment processes, and ventilation air methane (VAM) from coal mining. Red mud is used as oxygen carrier (OC) after calcination and crushing, sludge after drying and crushing is used as fuel for reduction process and VAM is used as gas for oxidation process. The experimental results of 80 cycles show that the carbon conversion and CO₂ selectivity of the reduction process are stable at 85% and 99%, respectively. And SEM and XRD indicate slight sintering and agglomeration of oxygen carriers. The mechanical strength test results show a minor decrease in particle strength after 80 cycles of OC. Although the reactivity of red mud as OC is not as good as that of artificially prepared OC, this deficiency is acceptable considering its cheapness and high yield. It is worth noting that the products of sludge combustion (mainly silica) are massively deposited in the reactor and mixed with OC, which may greatly affect the performance of OC, and the method of separation of the two should be further considered in future work.