Key Takeaways & Executive Findings
- •• • Post-optimization, NOx hourly average concentration decreased from 315.00 mg·m−3 to 181.69 mg·m−3 (42.3% reduction), and CO from 209.57 mg·m−3 to 73.46 mg·m−3 (65.0% reduction), with exceedance hours dropping from 59.52% to 8.93% for NOx and from 83.33% to 5.99% for CO, demonstrating enhanced combustion control and pollutant suppression. • • The dual-combustion-chamber design (primary pyrolysis at 550–650 °C, secondary oxidation above 900 °C) enables stable gasification of low-calorific MSW (3,800–5,800 kJ·kg−1) with high moisture content (20–35%), addressing the bottleneck of small-scale facilities in cold regions. • • In-situ leachate recirculation achieved complete on-site leachate disposal under the project's leachate yield, without significant adverse effects on combustion conditions, providing a cost-effective alternative to external leachate treatment and reducing secondary pollution risks. • • The system achieved continuous stable operation with an 80 t·d−1 capacity, and all monitored gaseous pollutants met national emission standards, validating the engineering optimization for county-level MSW treatment in arid and cold regions.
Abstract
Municipal solid waste (MSW) management in Inner Mongolia has long relied on landfilling, facing land scarcity and leachate management challenges. This study addresses the region's dry, cold climate, high proportion of agricultural and livestock waste, fluctuating moisture content, and weak leachate treatment capacity. An engineering optimization was implemented on an 80 t·d−1 vertical rotary gasification-incineration system featuring a dual-combustion-chamber design (primary chamber for medium-temperature pyrolysis-gasification at 550–650 °C and secondary chamber for high-temperature oxidation above 900 °C), coupled with in-situ leachate recirculation. Field measurements showed improved processing capacity and continuous operation stability. Under the project's leachate yield, in-situ recirculation achieved on-site disposal without significant adverse effects on gasification-incineration conditions, providing buffering against moisture fluctuations. During the monitoring period, major gaseous pollutant emissions remained below current national standards. The results provide engineering references for the co-processing and stable operation of small-scale county-level MSW treatment facilities.
1. Introduction
Municipal solid waste (MSW) management in northwestern China, particularly in Inner Mongolia, has historically depended on landfilling due to the low daily waste generation (typically below 100 t) and low calorific value (often <5,000 kJ·kg−1) that render waste-to-energy incineration plants economically unviable. This reliance on landfilling exacerbates land scarcity and poses risks of soil and groundwater contamination from leachate. The region's unique waste composition—high proportions of agricultural and livestock waste, fluctuating moisture content (20–35%), and seasonal variability—further complicates treatment. Existing gasification-incineration technologies face operational challenges, including unstable furnace temperatures, fluctuating CO and NOx emissions, and blockages in feeding and ash discharge systems, which hinder continuous operation.
This study addresses these bottlenecks by implementing a series of targeted engineering optimizations on an 80 t·d−1 vertical rotary gasification-incineration system in a typical county in Inner Mongolia. The core innovation lies in the dual-combustion-chamber design, which separates medium-temperature pyrolysis (550–650 °C) from high-temperature oxidation (>900 °C), enabling stable treatment of low-calorific, high-moisture waste. Additionally, in-situ leachate recirculation is integrated as a cost-effective leachate management strategy, eliminating the need for external treatment and reducing secondary pollution. The optimization focuses on improving feed system reliability, stabilizing combustion conditions, and enhancing pollutant control, as evidenced by post-optimization emission data. This case provides a replicable engineering model for small-scale MSW treatment facilities in similar arid and cold regions.
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ZHANG Zhefeng, LI Wenkai, GU Qi, LIU Jianguo, SHI Lin, ZHANG Jialong, WANG Qunhui, MA Lisha, ZHENG Tianlong (2026). Engineering Optimization of an 80 t·d−1 Municipal Solid Waste Gasification-Incineration Furnace: A Case Study in Inner Mongolia. Chinese Journal of Environmental Engineering. https://doi.org/10.12030/j.cjee.202511050
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Frequently Asked Questions
What were the specific structural modifications implemented to improve feed system reliability and prevent blockages?
The study implemented source material control measures, including enhanced waste inspection and pretreatment to enforce particle size limits, which mitigated compaction, bridging, and blockage in the feed system. Additionally, operational adjustments to the rotary furnace and combustion air distribution were made to stabilize the pyrolysis and oxidation processes, as reflected in the significant reduction of CO and NOx emissions.
How does the dual-combustion-chamber design handle the low calorific value and high moisture content of the waste?
The primary chamber operates at 550–650 °C under oxygen-lean conditions, promoting pyrolysis and gasification of the high-moisture waste. The secondary chamber maintains temperatures above 900 °C to ensure complete oxidation of the generated syngas, achieving stable combustion despite the low calorific value (3,800–5,800 kJ·kg−1) and moisture fluctuations (20–35%). This design decouples the drying and combustion stages, enhancing process stability.
What is the operational impact of in-situ leachate recirculation on combustion conditions and pollutant emissions?
In-situ leachate recirculation was implemented without significant adverse effects on gasification-incineration conditions. It provided a buffering effect against moisture fluctuations, and under the project's leachate yield, achieved complete on-site disposal. Post-optimization, NOx and CO emissions decreased substantially, indicating that leachate recirculation did not compromise combustion efficiency or pollutant control.
What are the scalability and cost implications of this optimized system for other county-level facilities?
The system is designed for small-scale capacities (80 t·d−1), which are typical for county-level facilities in northwestern China. The engineering optimizations, including leachate recirculation, reduce operational costs by eliminating external leachate treatment and improving energy recovery (e.g., waste heat for heating). The demonstrated stable operation and emission compliance suggest that this approach can be replicated in similar regions, though site-specific waste composition and climate must be considered.
How were NOx emissions controlled without dedicated SNCR/SCR systems?
NOx control relied on the staged air supply inherent to the dual-combustion-chamber design, combined with optimized air distribution and temperature control. This approach achieved source-level suppression and peak shaving, as evidenced by the reduction in NOx hourly average from 315.00 mg·m−3 to 181.69 mg·m−3 post-optimization, with exceedance hours dropping from 59.52% to 8.93%.
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