exhaust-gas-from-hazardous-waste-storage

The exhaust gas from hazardous waste storage facilities has a complex composition, often containing volatile organic compounds (VOCs), odorous gases (such as hydrogen sulfide and amines), and small amounts of toxic gases. Treatment requires a combination of "pretreatment + core purification + in-depth safeguards." The following is a typical process flow chart:

Hazardous Waste Storage Exhaust Gas Treatment Process

Exhaust Gas Collection

Exhaust gases emitted during hazardous waste storage are collected in a sealed manner using devices such as overhead hoods and side-suction air curtains. These gases are then transported to the treatment system using negative pressure from fans (preventing them from spreading outside the facility).

Pretreatment
- Particle Filtration: Exhaust gas first enters a bag filter or HEPA filter to remove dust and small amounts of solid particulate matter to prevent clogging of subsequent equipment.
- Humidity Control: If the exhaust gas has high humidity (such as during the rainy season or when hazardous waste containing moisture is volatilized), condensation is used to remove water, or heating is used to reduce humidity to minimize degradation of adsorption/catalytic efficiency. 3. Core Purification
- Spray Absorption: Acidic/alkaline scrubbers (selected based on the exhaust gas's properties) are used to neutralize acidic and alkaline gases (such as ammonia and hydrogen sulfide) in the exhaust gas while dissolving some soluble VOCs.
- Activated Carbon Adsorption: After spraying, the exhaust gas enters the activated carbon adsorption tower, which absorbs remaining VOCs and odorous substances (the activated carbon requires regular replacement or regeneration).
- Catalytic Oxidation (Backup): If the exhaust gas concentration fluctuates significantly, a catalytic oxidation device (such as CO) is activated to oxidize residual organic matter into CO₂ and water under the action of the catalyst, ensuring purification efficiency.

Advanced Treatment and Discharge
- Demisting and Drying: A demister removes water vapor and mist droplets from the exhaust gas.
- Online Monitoring: Treated exhaust gas is tested with online VOC and odor concentration monitors. Once it meets the standards, it is discharged to a high altitude (generally ≥15 meters) through a dedicated exhaust stack.

The core of this process is "physical and chemical absorption followed by adsorption/oxidation." To address the complexity and volatility of hazardous waste storage and waste gas, multi-stage treatment is used to ensure compliance with standards. Emergency adsorption units are also equipped to handle sudden concentration increases.

Common treatment processes for hazardous waste storage facilities are as follows:

The secondary activated carbon adsorption chamber in hazardous waste storage facilities is a multi-stage adsorption treatment device designed for waste gas (containing VOCs, odorous substances, etc.) from temporary hazardous waste storage facilities. Its core feature is the cascade connection of two activated carbon adsorption units to improve waste gas purification efficiency. Its features and functions are as follows:

Core Advantages
- Higher Treatment Efficiency: The primary adsorption chamber first absorbs the majority of pollutants, while the remaining unabsorbed waste gas enters the secondary adsorption chamber for further purification. This dual adsorption process significantly reduces pollutant concentrations, ensuring compliance with emission standards. It is particularly suitable for hazardous waste storage environments with complex pollutant compositions and large concentration fluctuations.
- Extended activated carbon replacement cycle: The two-stage adsorption process works in tandem, with the primary stage carrying the primary adsorption load and the secondary stage providing additional deep purification. This reduces the wear rate of the single-stage activated carbon and reduces the cost and workload of frequent replacement. - Responding to Sudden Concentration Increases: When hazardous waste storage experiences a temporary rise in exhaust gas concentration due to increased volatilization from temporarily stored waste (e.g., elevated temperatures or the unique characteristics of newly stored hazardous waste), a secondary adsorption system can act as a "buffer," preventing single-stage adsorption from saturation failure and enhancing system stability.

Common Designs and Applications
- Typically, the two-stage adsorption chambers can be of the same type (e.g., both top-mounted or drawer-mounted), or they can be combined as needed (e.g., top-mounted for the first stage and drawer-mounted for the second stage), flexibly adapting to installation space and maintenance requirements.
- During operation, the performance of the two adsorption stages should be monitored separately. Saturated activated carbon in the first stage should be replaced first, while the replacement cycle for the second stage can be appropriately extended, balancing efficiency and cost-effectiveness.

This design, through a "double insurance" mechanism, provides more reliable treatment of hazardous waste storage exhaust gas, reduces environmental risks, and is a commonly used enhanced solution for exhaust gas treatment at hazardous waste treatment sites.