It is a constant challenge to comply with the strict standards on discharging rainwater, in the recycling industry in particular. Using the right treatment methods here will already save you a great deal of worry. The combination of an Oxycon with a Mobicon installation from Desotec appears to work very powerfully for specific applications, while also resulting in a lower TCO (Total Cost of Ownership).

A French company, specialised in the collection and recycling of glass waste, was in search of the right solution to effectively treat rainwater to fully comply with strict discharge standards. Just like numerous sector players, this company stores waste fractions in the open air. During rainfall the water seeps through the waste mountain and mixes with residual products (for example yoghourt, wine, etc.) still present on the glass fragments.

As a result, this rainwater contains three types of contaminants: COD (organic materials), BOD (biodegradable materials) and suspended solids. After the company had seen how a competitor had effectively tackled the situation, it called upon Desotec to find an efficient and complete solution.

Combined system

After a careful study of the problem, our project team advised the combination of a Mobicon and an Oxycon installation. Oxycon is a container system in which the contaminated water circulates, with the addition of oxygen bubbles through a specially designed injection pipe. In so doing it also injects oxygen into the activated carbon filter, making it work as a biological purification stage. Pre-filtration consisting of a candle filter already takes care of the removal of the suspended solids.

The project team had to come up with an ingenious solution. If it does not rain the recycling specialist has no rainwater to discharge, but it is important that circulation in the Oxycon functions constantly to avoid the build-up of sludge. We succeeded in optimally squaring the circle.

Four advantages

Since this combined system has been in use at the customer, four birds have been killed with one stone. Firstly, the effluent from the purification installation now complies with the discharge standards for COD, BOD and suspended solids. Moreover, the Oxycon installation considerably relieves the activated carbon filter by triggering the chemical oxidation process. It ensures that the activated carbon of the Mobicon saturates much less quickly, so the working life of this mobile purification solution is at least doubled. That leads to a significant reduction of the TCO.

Oxycon is a robust installation requiring little maintenance, it works autonomously, and relieves most of our customer’s concerns. The system will undoubtedly appear essential in the future for other companies in the growing recycling sector, where many companies are confronted by the challenge of discharging contaminating waste and rainwater into the surface water in an economically and ecologically responsible way.

At DESOTEC’s facilities, all used carbon is analysed so the right measures can be taken for handling and removing the saturated carbon out of the mobile filters. All molecules that were adsorbed on the activated carbon at the customers’ site, are desorbed inside DESOTEC’s reactivation furnaces. These contaminants are then fully destroyed, in accordance with National and European legislation, by an incineration and neutralisation setup. The entire installation and it's emissions are under continuous on-line monitoring, which guarantees that only harmless water vapour is seen exiting the chimney.