Evaluating Optimum Hydrated Lime Dosage in Reducing Stack Emissions During Incineration of Waste

Abstract

Incineration is any procedure, technique or method that transforms waste to flue gases and by-products by means of oxidation. Although the recommended way of treating healthcare risk waste is through incineration, the utilization of incinerators is still disputable. The fundamental problem for incinerators in the Republic of South Africa started with the new amended Section 21 of the National Environmental Management Act: Air Quality Act known as NEMA: AQA 39 of 2004 that requires stack emissions to be reduced by almost 50%. Since the promulgation of the standard, incineration facilities have not been complying with the emissions standard. This study was conducted to investigate the optimum hydrated lime [Ca(OH)2] dosage required to reduce acid gas emissions to the required level. The dosage rate was then raised and kept between 2.5 and 3.5 kg/h. This technology was able to achieve a high removal efficiency of 97% for HCl, 86% for HF, 83% for NO, 87% for SO2 and 74% for NO2. The optimum emissions removal temperature for HCl was between 1190°C and 1200°C, 1020°C for SO2 and NO2, and between 1120°C and 1200°C for NO2. The optimum Ca(OH)2 dosage for maximum NO removal was 3.1 kg/h, HF was 2.9 kg/h, SO2 was 2.8 kg/h, NOx was 2.8 kg/h and HCl was 3.2 kg/h.

Optimizing the Elimination of Dioxin-Like Compounds (PCDD/Fs and PCBs) Through Effective Combustion Practices in the Flue Gas in the Medical Waste Incineration Facility

“…PCDD/Fs and dioxin like polychlorinated biphenyl (dl-PCBs) are known contaminants belonging to the group of compounds classified as Persistent Organic Pollutants (POPs). PCDD/Fs compounds are created in all processes associated with the combustion of organics within the presence of different chlorine compounds (modern and domestic coal burning, waste incinerators, sinter plants, cement industry, ferrous and non-ferrous metallurgy, engine transport) [2][3][4]. Due to their lipophilic nature, they are known to bio accumulate, are carcinogenic and pose a significant health risk even at low concentrations [5].…”