Reducing pesticide residues from the manufacturing of crop protection chemicals

Agriculture in Europe is reliant on fertilizers and chemical plant protection – almost 400 000 tonnes of pesticides and other phytosanitary products were sold in the EU in 2016. Yet the chemicals used during their manufacture, as well as residue from the pesticides themselves, can contaminate wastewater. If this enters the natural environment, it has the potential to cause pollution and damage. Manufacturers are therefore subject to strict laws concerning the treatment and disposal of wastewater, which can be contaminated by processes such as chemical side reactions, spent acids and caustic streams, condensed steam, and waters from rinsing the machinery after usage. Mobile activated carbon filtration technology, as used by DESOTEC, has been designated a Best Available Technique (BAT) for the purification of phytosanitary wastewater due to its proven ability to reduce contaminants such as adsorbable organic halides (AOX) and organic matter to legal limits.

The problem

One factory producing chemical crop protection products needed to reduce AOX levels and pesticide residues in its wastewater to very low legal levels before it could be transported to a nearby treatment plant.

Rather than store the contaminated water in giant tanks on site until it could be sent for specialist disposal – a process that is both costly and inconvenient – the manufacturers sought a more efficient solution.

In the case of this factory, there was a further challenge: the concentrations of chlorinated, fluorinated and brominated AOX components all fluctuated, meaning that any decontamination solution had to be flexible enough to cope. 

The solution

Desote's Mobicon model, the largest of its series of mobile activated carbon filters designed to decontaminate wastewater, proved to be the ideal solution for this phytosanitary plant.

Most importantly, the Mobicon is highly effective, using Organosorb carbon to purify the water of AOX and pesticides to safe levels for proper disposal.

Furthermore, is simple to install. It can be fitted on a trial or temporary basis, requiring little investment from the manufacturer.

It is easy to connect, and the filters can be changed in around one hour. This is in contrast to fixed filter systems, where the exchange process is lengthy and requires a great deal of staff time.

Finally, it is modular and very flexible, meaning it was able to adapt to the fluctuating flows of different contaminants produced by the factory.

The Mobicon can be set up in series to handle greater levels of contamination. The first filter cleanses the water of most of the pollution, while the second effectively ‘polishes’ the cleansed water.

This system also means that when one filter becomes saturated, the second acts as a back-up.

Water column tests can also be carried out to determine the type of carbon needed, and to check the filters are purifying the wastewater to the desired level.

The results

In the case of this phytosanitary factory, the Mobicon has proven able to treat peaks of AOX of 300 mg/L, reducing them to the legal limit of 0,2 μg/L.

It handles a flow of 2 m³/h effectively, making for a smooth and efficient operation.

When one filter is saturated, it can be swiftly changed and transported by DESOTEC off-site, meaning there is no need for the client to handle any new or spent carbon.