A company from Germany has focused on recycling PET bottles, glass, wood, and photovoltaic systems. It operates several sites for this purpose. For the plastics recycling site, the company wanted a treatment plant to discharge the wash water produced into the municipal sewage treatment plant. Every day, about 36 cubic metres of wash water are produced by washing the plastic.
The company’s goal was to discharge the wastewater into the municipal sewer system. The challenge was to reduce the COD from over 11,000 mg/l to below 1,000 mg/l. The company was paying a heavy pollution charge due to the high COD value. To avoid this, it has to comply with the required COD values in the long term.
At the beginning, the company provided wastewater samples, which the in-house ClearFox® laboratory examined by means of several jar tests. These detected the high COD of over 11,000 mg/l. The ClearFox® team is thus able to understand the customer’s exact requirements to offer an efficient treatment plant as a result.
The best solution to achieve the COD value of below 1,000 mg/l is a combination of dissolved air flotation and fixed bed biological reactor. Since the jar test showed that the substances are easily suspended in the wash water, dissolved air flotation is best suited to remove the suspended solids.
The subsequent step is a fixed-bed biological reactor, which biodegrades the non-suspended substances in the wash water. The microorganisms present in the wastewater settle on the carrier material and respire the contaminants. The addition of air is precisely adapted to the remaining contamination so that the purification capacity is utilised as efficiently as possible. During the biological treatment stage, a sludge is produced which is separated from clear water by a lamella clarifier.
After both DAF and FBBR treatment, sludge is produced that still has a very high water content. A sludge dewatering unit reduces the water content, so that the transport and storage costs are reduced to a minimum.
The ClearFox® team installed the entire treatment plant in two 40-foot ISO sea containers. These are placed on top of each other at the customer’s site to make the best possible use of the space on the site. The ClearFox® team took over the planning, construction, delivery, installation, and commissioning of this project.