Removal of hydrogen sulfide with granulated coal ash under aerobic and anaerobic conditions

Abstract

Annual emissions of fly ash from the burning of coal have increased to approximately 750 million tons. It is hoped that new applications utilizing by-products from coal-fired power plants will contribute to further waste reduction and set the standard for industrial-scale recycling. The purpose of this study was to evaluate the removal rate of hydrogen sulfide by a new recycled material called granulated coal ash, which is produced from coal fly ash from coal thermal electric power stations and blast furnace cement. A batch experiment was carried out to evaluate the removal rate of hydrogen sulfide by granulated coal ash under both anaerobic and aerobic conditions. The granulated coal ash could remove hydrogen sulfide under both anaerobic and aerobic conditions. However, the maximum removal of hydrogen sulfide by granulated coal ash was only 5.1 mg-S g−1 under anaerobic conditions because the manganese oxide which oxidizes hydrogen sulfide to sulfur could not be regenerated under anaerobic conditions. In contrast, the rate constant for hydrogen sulfide under aerobic conditions was high due to the multiplier effect attributed to both increasing Eh and the regeneration of manganese oxide by dissolved oxygen.