Cooperation with industrial stakeholders in Grevesmühlen
Solution to which problem
Indirect discharges from industries often pose a risk of disturbances of processes at the WWTP. A common approach to reduce the negative impacts is to define criteria for the composition of wastewater accepted. In Germany, these criteria often refer to DWA guideline M 115-2 (2013). Monitoring of the indirect dischargers is necessary. Conflicts are likely to happen if discharges do not meet the requirements.
The wastewater treatment plant in Grevesmühlen serves 65 000 PE with a high share of industrial discharges. The WWTP serves as a central sludge treatment facility for surrounding smaller WWTP. Co-substrates are accepted to increase the biogas production. After years of renovation and extension, the WWTP is now equipped with a thermal disintegration unit and a side stream deammonification unit. Still indirect discharges from food industry reduce maintenance intervals of e.g. plate aerator.
The Zweckverband decide to approach indirect dischargers in a cooperative way. On the one hand short-term exceeding of concentration limits is accepted and balanced with a heavy polluter fee. Of course, this does not refer to toxic or non-degradable substances.
On the other hand, the Zweckverband offers to manage pre-treatment facilities either on-site at the manufacturing location or centralised at the WWTP. It is beneficial for the companies’ staff who can focus on the clean manufacturing area and do not need to change for the maintenance of the pre-treatment facilities. The Zweckverband is profiting from the qualified workers, who have to visit the pre-treatment facility anyway on a regular bases to collect 24h mixed samples.
Regarding wastewater from a dairy it was decided to stop the operation of an outdated flotation on site in favour of a flotation unit at the WWTP. The new unit will allow the operator to treat the wastewater from the dairy to the extent required. In case a C-source is needed for denitrification, the substrate can be added via the dairy wastewater, which in terms is beneficial for the treatment process. It is not necessary to transport the flotated sludge by trucks from the dairy to the WWTP.
In the win-win situation both indirect discharger and operator of the WWTP profit from the offered services. Pre-treatment including optional maintenance as a service is managed by professional qualified staff. In terms the number of unpleasant surprises due to unexpected discharges is significantly reduced. It is easier to operate the WWTP in a smart way since the reliability of predictions of the loads and flows is increased.