Wastewater treatment at a chemical site rich in tradition

Developed Solution and Applied Process Combination

The plant produces demineralised water from river water. In addition, part of the plant can also be used for the filtration of cooling tower water. In addition to the main processes of ultrafiltration, reverse osmosis and ion exchange, the plant also includes hot water production from steam, pre-filtration and pre-heating, chemical storage and supply, and wastewater collection and neutralisation.
The plant is part of a larger project at the site to meet the increased demand for cooling capacity and demin water. The plant is also designed in such a way that it can be expanded at a later date.

The ion exchange process is suitable for reliably achieving the required specification for the customer's demin water, while at the same time maintaining a high yield. Since the river water has a high salt concentration at times, a reverse osmosis plant is installed upstream of the ion exchange process in order to economise on regeneration chemicals. Furthermore, the reverse osmosis system is suitable for removing TOC from the water.

The potential for scaling on the reverse osmosis is reduced by dosing antiscalant and acid. To protect the RO from fouling and to allow reliable and efficient operation, the river water is first treated by ultrafiltration. The dosing of flocculant further facilitates the removal of part of the TOC via ultrafiltration.

In addition, the ultrafiltration process is suitable for treating a partial flow of the cooling water. Both river water and cooling water partial flow treatment are located in the same building, which leads to synergy effects. For example, the chemical and backwash system as well as the wastewater collection and neutralisation can be utilised for both plants.

Overall, the plant includes all the necessary equipment for cleaning membranes and resins, both for regular and special treatments.

In order to be able to treat the river water economically and efficiently during the winter months, the plant also includes a hot water station. This uses steam to generate hot water, which is then used to preheat the river water. The plant also includes a recuperator stage to use thermal energy from the cooling water for preheating.

All wastewater generated during the process is collected and can be neutralised directly in the plant if necessary. The wastewater disposal is coordinated with local conditions.

In addition to the mechanical installation, the system also includes an electrical control system from which the plant can be safely controlled and monitored. Particular attention is paid to a reliable and safe plc system, taking into consideration available redundancies.

Facts & Figures

• Feed water composition: TSS max 4 mg/l, turbidity max 1,94 mg/l, conductivity 706 – 1827 µS/cm

• Demin production: norm 375 m³/h, max 450 m³/h, expandable to max 775 m³/h

• 8 lines of ultrafiltration plants @ 150 m³/h filtrate, 5 lines of reverse osmosis plants @ 110 m³/h permeate, 4 lines of demin plants @ 150 m³/h