International Journal of Waste Resources

Parameters of Gasification Process for Production of Hazardous Pollutants

Hanafiah Nawanir^* Department of Environmental Engineering, National Central University, Tao-Yuan Taiwan, P.R. China
^*Correspondence: Hanafiah Nawanir, Department of Environmental Engineering, National Central University, Tao-Yuan Taiwan, P.R. China, Email:

Received: 28-Apr-2023, Manuscript No. IJWR-23-21469; Editor assigned: 01-May-2023, Pre QC No. IJWR-23-21469(PQ); Reviewed: 15-May-2023, QC No. IJWR-23-21469; Revised: 22-May-2023, Manuscript No. IJWR-23-21469(R); Published: 29-May-2023, DOI: 10.35248/2252-5211.23.13.530

Description

Waste gasification is a thermal conversion process that converts organic waste materials into a combustible gas mixture called syngas, which can be used for energy and chemical production. Gasification has several advantages over direct combustion of waste, such as higher efficiency, lower emissions of some pollutants, and flexibility in feedstock and product options. However, gasification also poses some challenges and risks, especially regarding the formation and release of hazardous pollutants during the process. One of the main sources of hazardous pollutants in waste gasification is the presence of chlorine and other halogens in the waste feedstock. Chlorine can be found in various types of waste, such as plastics, paper, textiles, and biomass. When these wastes are gasified, chlorine can react with organic compounds and form toxic chlorinated compounds, such as Chlorobenzenes (ClBzs), Chlorophenols (ClPhs), Polychlorinated Dibenzo-P-Dioxins and Dibenzofurans (PCDD/Fs), and Dioxin-Like Polychlorinated Biphenyls (dl- PCBs). These compounds are known to have carcinogenic, mutagenic, endocrine-disrupting, and immune-toxic effects on humans and wildlife.

The formation and emission of these chlorinated compounds depend on several factors, such as the type and composition of the waste feedstock, the temperature and oxygen level of the gasification process, the residence time and mixing of the gasifying agents, and the type and efficiency of the emission control devices. Generally, higher temperatures and lower oxygen levels tend to reduce the formation of chlorinated compounds, while longer residence times and better mixing tend to increase it. The emission control devices, such as scrubbers, filters, catalysts, and adsorbents, can help to remove or destroy some of the chlorinated compounds from the syngas or the flue gas before they are released to the atmosphere.

Another source of hazardous pollutants in waste gasification is the presence of heavy metals in the waste feedstock. Heavy metals can be found in various types of waste, such as batteries, electronics, paints, and ash. When these wastes are gasified, heavy metals can volatilize and partition into different phases: gas phase (syngas or flue gas), solid phase (char or slag), or liquid phase (tar or wastewater). The distribution of heavy metals among these phases depends on several factors, such as the type and concentration of the metal, the temperature and pressure of the gasification process, the composition and pH of the gasifying agents, and the type and efficiency of the emission control devices.

The volatilization and partitioning of heavy metals can have significant environmental and health implications. For example, mercury is a highly volatile metal that can easily escape from the gasification system and enter the atmosphere. Mercury is a neurotoxic element that can accumulate in the food chain and cause adverse effects on humans and wildlife. Other metals, such as cadmium, lead, arsenic, chromium, nickel, and copper, can also volatilize to some extent and pose health risks if inhaled or ingested. Some metals can also remain in the solid or liquid phases and contaminate the char, slag, tar, or wastewater produced by the gasification process. These by-products may require further treatment or disposal to prevent leaching or runoff of heavy metals into soil or water bodies.

Conclusion

Waste gasification is a promising technology for converting waste into valuable products while reducing greenhouse gas emissions. However, it also involves some challenges and risks regarding the formation and release of hazardous pollutants during the process. These pollutants include chlorinated compounds and heavy metals that can have negative impacts on human health and the environment. Therefore, it is important to optimize the gasification process parameters and apply adequate emission control devices to minimize these pollutants. It is also essential to monitor and regulate the emissions from waste gasification facilities to ensure compliance with environmental standards.