Wastewater treatment and grease recovery at the Oldenburg site.
Durch die Umstellung auf stehende Sammeltanks wird das eingepumpte Material schneller in Fett-, Wasser- und Schlammphase getrennt. Quelle: Nehlsen
A logistical challenge involved in the installation of the new GRP storage tanks, with a capacity of 35 m³ and a height of 7 metres, at Nehlsen’s Oldenburg site. Source: Nehlsen
Die biologische Fettnachbehandlung BIFENA bei Nehlsen am Standort Oldenburg. Quelle: Nehlsen
Short overview
Oldenburg, Germany
Trade & industry
Custom Solutions
With a newly designed wastewater treatment plant, Nehlsen AWG GmbH & Co. KG is investing in a sustainable infrastructure for the treatment of greasy wastewater at its Oldenburg site. In collaboration with KESSEL, an integrated concept has been developed that combines dewatering technology, grease separation and the subsequent recovery of the separated grease phase.
Increasing demands for water protection and stricter legal requirements call for high-performance solutions for the treatment of industrial wastewater containing grease. Particularly fluctuating load levels and stable grease-water emulsions place high demands on planning and plant engineering.
Nehlsen is one of Germany’s leading recycling and waste management companies and, according to the company, employs more than 3,000 staff at around 70 sites across Europe and Africa. At the Oldenburg site, the existing plant was modernised with the aim of further automating wastewater treatment and recycling the separated fat phase.
Holistic plant design
The project centred on the modernisation of the storage and treatment technology. In collaboration with the design consultancy GEWINNER Architekten + Ingenieure, a comprehensive system comprising new storage tanks, optimised pipework routing and additional treatment stages was developed. End-to-end 3D planning facilitated the coordination of the complex pipework, which featured five pipe levels and three large pumps.
Three bespoke GRP storage tanks, each with a capacity of 35 m³, were installed, along with a discharge tank for automated weekend operation. The switch from horizontal to vertical tanks improves the phase separation of grease, water and sludge. This allows the grease phase to be skimmed off specifically and sent for further recycling.
Multi-stage treatment to ensure safe discharge limits
The existing grease separators, compliant with DIN EN 1825 and DIN 4040-100, were supplemented with the KESSEL DOS dosing station and the BIFENA biological treatment system. This was based on an analysis of the wastewater profile carried out over several weeks.
Through the targeted dosing of flocculants, emulsified fats and fine solids are bound together to form larger particles and separated out. During operation, five cubic metres of water are treated every three hours, whilst five litres of flocculant are dosed at the same time. This reduces the concentration of lipophilic substances, bringing it below the required limit values.
The separated fat phase is then fed into biogas plants for further utilisation.
Biological post-treatment
The BIFENA small-scale biological treatment plant is used to reduce the residual organic load. As a moving-bed biofilm reactor, it reliably breaks down organic matter with the aid of microorganisms and reduces the COD and BOD₅ values. Following the start-up phase, the plant is designed to operate largely automatically. The treated water is then reused within the plant as process water. This reduces the demand for fresh water for suitable operational applications.
Coordinated system technology
The project in Oldenburg combines plant design, grease separation, chemical flocculation and biological wastewater treatment within a coordinated overall system. The individual process stages perform different tasks in the treatment of the wastewater generated and the separation of the grease phase.
For designers, architects and installers, the project highlights the aspects that must be taken into account when designing complex wastewater treatment plants: analysing the composition of the wastewater, coordinating the individual treatment stages, integrating the pipework and pumping systems, and monitoring the relevant operating parameters.
