Filtering COD, BOD and suspended solids for a glass recycling company

For the growing recycling sector, complying with the strict standards on discharging rainwater is a constant challenge. By using the right treatment methods, you can save your company a great deal of trouble. The combination of a Desotec Mobicon filter with an alternative treatment called an Oxycon has been shown to work effectively and lower total cost of ownership (TCO).

The problem

A French company, which specialises in the collection and recycling of glass waste, was searching for a way to treat rainwater to meet strict discharge limits.

Like many similar firms, this company stores waste fractions in the open air. When rain falls, it seeps through the piles of waste and mixes with residual products (e.g. yoghurt or wine) on the fragments of glass.

The resulting rainwater run-off contains three types of contaminants: organic materials, measured by chemical oxygen demand (COD); biodegradable materials, measured by biological oxygen demand (BOD); and suspended solids.

After seeing how a competitor had tackled this problem effectively, the company turned to Desotec to find a solution.

The solution

After studying the issue carefully, our project team decided to use a candle filter to remove suspended solids, before passing the water through both a Desotec Mobicon filter and an Oxycon installation for biological purification.

Oxycon is a container system which injects oxygen bubbles into contaminated water through a pipe. By placing this before the Mobicon filter, it also adds oxygen to the activated carbon, making it work as a biological purification stage.

It’s important to keep water circulating in the Oxycon continuously to avoid the build-up of sludge, but the company only has water to treat when it rains. The project team found an ingenious way to square this circle and optimise the system.

The results

The combined system kills several birds with one stone.

The wastewater now complies with discharge standards for COD, BOD and suspended solids. The Oxycon installation also relieves pressure on the Mobicon filter by triggering the chemical oxidation process. This means the activated carbon saturates far less quickly, so the working life of this mobile purification solution is at least doubled. That significantly reduces the TCO.

Oxycon is a robust installation that works autonomously and requires little maintenance.

We are confident that this combined system will become essential for other recycling companies who are facing the challenge of discharging rainwater in an economically and ecologically responsible manner.