Air Treatment System for Sludge Dryer Emissions – WWTP Application
Technical Summary
Application: Sludge drying
Industrial sector: Wastewater treatment
Air flow rate: 6,000 Nm³/h
Air characteristics: humid process air
Main pollutants: H₂S, ammonia, sulfur compounds, VOCs
Treatment lines: 2
This sludge dryer odour control system is designed for wastewater treatment plants handling complex industrial emissions.
Project Overview
Sludge drying processes used in wastewater treatment plants generate complex gaseous emissions containing hydrogen sulfide, ammonia and various odorous organic compounds released during thermal treatment of sewage sludge.
For the sludge drying units, two dedicated air treatment systems were engineered and installed to ensure reliable odour abatement.
Each system was designed to treat process air extracted directly from the sludge dryer and combines multiple treatment stages to address the complex chemical composition of the emission stream.
Engineering Challenges
Air emissions generated by sludge dryers present several challenges for air pollution control systems:
These conditions require a multi-technology treatment approach, capable of handling different pollutant classes within the same emission stream.
Sludge dryer odour control System Configuration
Each treatment line integrates several sequential technologies.
Venturi Scrubber + Packed Column
The first treatment stage consists of a wet scrubber system composed of a Venturi section followed by a packed column.
The Venturi section improves gas–liquid contact and promotes removal of dust and soluble compounds.
The packed column increases gas–liquid contact time and allows efficient absorption of odorous pollutants.
Main design parameters:
Biofiltration Stage
Downstream of the chemical scrubber, the air stream is treated through a biofilter designed to biologically oxidize residual odorous compounds.
The biofilter uses wood chips as filtering media, providing a suitable environment for microbial populations capable of degrading sulfur compounds.
Main characteristics:
Air Conditioning System
To maintain optimal operating conditions for the biofilter, the system includes an air conditioning section with electric heating.
This stage stabilizes temperature and humidity before biological treatment.
Activated Carbon Polishing Filters
The final stage consists of activated carbon adsorption filters designed to remove trace pollutants remaining after biological treatment.
Each filter contains approximately 2,500 kg of activated carbon, complemented by impregnated alumina for enhanced removal of sulfur compounds.
Results
The sludge dryer odour control system ensures stable performance and reliable odour abatement over time.
The installed systems provide stable treatment of emissions generated by sludge drying operations, ensuring reliable odour abatement and compliance with environmental regulations.
The integration of chemical scrubbing, biofiltration and adsorption allows progressive removal of pollutants with different chemical properties, increasing operational robustness.