Ensure process continuation by closing the water loop and minimizing fresh water use
Situation: Wastewater with complex organic load and high flow (100 m³/h) are represented in the case study 3. In this scenario the PVC production unit under consideration uses about 33% of the total on-site water consumption. Located in a coastal area with small river basin in southern Europe, the area is facing periodical water shortage.
Industry site characteristics: Fresh water limitations. Treatment of streams with high organic load, out of regular wastewater treatment to advance loop closure and reduce energy demand.
Success indicators: Reduce fresh water independency by > 20%. Close loop process up to 90%. Economic feasibility.
The aim is to close the water loop for this production and to realize additional water savings of 25%. The technologies under investigation for the new treatment trains are membrane bioreactors (MBR), pretreatment for demineralization (multimedia filter or granular activated carbon), followed by reverse osmosis, ion exchange or membrane distillation.
•Demonstration of a process consisting of a MBR in combination with a desalination unit for the treatment of process water with a high fouling tendency in order to reuse the treated water in the PVC process.
•Stable operation of the treatment process for at least 12 months.
•Target values MBR: PVA < 1 mg/l and N-NH4+ < 2 mg/l with a complete removal of the BOD.
•Target value desalination: TOC < 10 mg/l; Al < 0.1 mg/l; conductivity < 10 μS/cm.
•Use the results of this demonstration to define the scale-up at industrial scale to implement a further reduction of fresh water use of ~ 25 % (means nearly close the water loop for the PVC plant).
The most efficient treatment train developed in the lab will be tested with 2 external wastewater and will be demonstrated on-site. The resulting treatment train concepts will be applicable for a wide range of polymerization processes in industry.
This project has received funding from the European Union Seventh Framework Programme (FP7/2007-2013) under grant agreement n° 280756.