Achieving compliance with new WGC emission limits

The BAT Conclusions for Common Waste Gas Management and Treatment Systems in the Chemical Sector (WGC) are important new regulations, issued under the Industrial Emissions Directive (IED) and are the outcome of the WGC BREF document.

The WGC BAT Conclusions apply to channelled and diffuse emissions to air from the chemical, petrochemical and pharma sectors. The industrial activities that fall within their scope are found in the Industrial Emissions Directive Annex 1, 4.1 to 4.6, and include the production of several types of chemicals:

• Organic (e.g. hydrocarbons, plastic, synthetic rubbers, dyes and pigments etc)
• Inorganic (e.g. sulphur compounds, metal oxides etc)
• Pharmaceutical products including intermediates
• Plant protection products or biocides
• Explosives

Published in 2022, the WGC BAT Conclusions must now be adopted into national law in each EU member state and implemented within four years – i.e. by December 2026. 

From that point, environmental authorities will start placing companies in the pharma, petrochemical and chemical industries under increased scrutiny to ensure they are compliant.

A multinational specialty chemicals company headquartered in France is facing new limits under the WGC BAT Conclusions on VOC concentrations in its air emissions. At one of their emission points, VOC concentrations can vary between 20 and 900mg/m³, of which approximately 70% is acetone.

Also present are various inorganic compounds, including up to 15mg/m³ of hydrogen chloride (HCl) and hydrogen cyanide (HCN).

To comply with the current carbon equivalent (CE) limit of 110 mg/m³, the company treats its emissions through scrubbing. However, this technology will be insufficient when the new CE limit of just 20mgC /m³ is imposed from December 2026 by the WGC BAT-AELs.

Moreover, the client will also have to comply with very low limits for certain other compounds, including: 10mg/m³ of HCl; 1mg/m³ of HCN; and 1mg/m³ of chloroform (TCM), dichloromethane (DCM) and chloromethane.

The company has a framework agreement with DESOTEC for the supply of our activated carbon filtration solutions for several water and air applications across various sites in Europe. Activated carbon is regarded as a Best Available Technology (BAT) for air purification, so the customer turned to us for help.

Evaluating filtration parameters for WGC compliance via a pilot test

We worked with the client on a  pilot project in 2024, installing a small activated carbon filter downstream of the scrubber.

The model used was an AIRCON 2000 C PE, designed to treat high concentrations in fairly low flow rates to meet very low emissions limits. 

Due to the presence of HCN and HCl acids, and the fact that the scrubber adds water to the airstream, we used a filter coated with polyethylene to withstand corrosion. 

It contained layers of different carbon grades: one was impregnated to adsorb the HCl and HCN; and another was microporous to capture even the smallest VOC molecules.

Acetone is reactive on activated carbon, so DESOTEC’s experts explained to the customer the potential risk of hotspots developing in the filter bed during adsorption. Given that adsorption is an exothermic reaction, and that there was oxygen present in this waste gas, we shared our recommendations regarding prevention, detection and action for hotspot management. 

Following our advice, the client measured carbon monoxide (CO) continuously at the filter outlet. On detecting several peaks, it then measured the CO at the inlet and discovered values were also high, meaning those peaks were not the result of hotspots within the filter. 

We advised the client to ensure a supply of nitrogen was on hand to douse the filter bed in the unlikely event that a hotspot should develop. 

The results of the pilot test showed the filter reduced the VOCs and inorganic compounds to zero. 

Despite the rather low flashpoint for acetone, the pilot test proved that we could reactivate the waste activated carbon after its usage and saturation.  This circular process is not only more sustainable, but also means lower TCO for the customer.

Next steps towards full-scale industrial installation and compliance

The client was pleased with the results, and gave us the go-ahead for a full-scale industrial installation in time for the December 2026 deadline.

This will involve passing the flow of 1710 m³/h  first through the existing scrubber to remove the bulk of the compounds. 

The airstream will then be treated by two AIRCON 3000 PE models in series containing impregnated carbon to treat the HCN and HCl, followed by two AIRCON HC-XL models filled with standard carbon to treat the VOCs.

Once saturated, the filters will be exchanged in a quick and simple process that causes minimal disruption or downtime. The closed filter units will be transported away from the customer’s site to DESOTEC’s own facilities, where we will sample and sort the waste activated carbon for reactivation.