Comparative study of carbon-deNO_x process by different sewage sludge chars

Area of Science:

• Environmental Science
• Chemical Engineering
• Materials Science

Background:

• Sewage sludge char (SC) is a potential reducing agent for flue gas denitrification.
• SC requires modification to improve its carbon-deNOx efficiency.
• Existing coal char (CC) has limitations in NOx removal.

Purpose of the Study:

• To compare the carbon-deNOx performance of different types of sewage sludge char (SC-R, SC-V, SC-K) against coal char (CC).
• To evaluate NO removal rates and secondary pollution.
• To identify optimal conditions and modified SC for flue gas cleaning.

Main Methods:

• Comparison of original (SC-R), pyrolytic volatiles activated (SC-V), and KOH activated (SC-K) sewage sludge chars with coal char (CC).
• Assessment of carbon-deNOx performance under varying oxygen concentrations (5-6% and 8-11%).
• Analysis of secondary pollutants (CO, NH3, HNCO, HCN) and physical-chemical properties.

Main Results:

• All SC types demonstrated >70% carbon-deNOx efficiency in 5-6% oxygen, outperforming CC.
• SC-V exhibited lower emissions of CO and gaseous nitrogen compounds.
• In 8-11% oxygen, performance order was SC-K > SC-R > SC-V > CC.
• Pyrolytic-volatile activation enhanced SC-V surface functional groups (C-O, C=O), aiding NO chemisorption.

Conclusions:

• Modified sewage sludge chars, especially SC-V, are effective agents for flue gas denitrification.
• SC-V is a promising reductant for carbon-deNOx within 300-350°C, offering reduced secondary pollution.
• Optimization of SC activation methods is key to enhancing its application in environmental remediation.