Water saving concepts with membrane technology
In order to reduce fresh water consumption to a considerably low level, OptiCycle W is the key technology. OptiCycle W process is based on membrane filtration. This solution is designed for the paper mill’s filtrate waters, in order to purify the water to a level where it can be used as an alternative to fresh water. Ultrafiltered water can be used instead of fresh water for certain low and high pressure showers in the wire section and for chemical dilutions.
Compact and controlled water management is dependent on a good basic process solution. The reduction of fresh water consumption always starts by optimizing the main process itself.
Therefore, in order to be sure that additional water treatment is worthwhile and can positively affect paper machine runnability and product quality, the basic process connections have to be taken care of.
When fresh water consumption is very low, special attention has to be paid to the efficiency of salt removal. Part of the ultrafiltrated water is treated with OptiFilter nanofiltration, which includes tighter membranes than OptiCycle W.
Metso Water Concept for Paper processes
Fresh water consumption
- Dimensioning for the capacity of 100% efficiency
- Cooling waters are not included in the consumption value
Water treatment
- OptiCycle W to remove solids, colloids and bacteria
- OptiFilter NF to remove salts in special cases
- Microflotation for press section waters to remove fines and pitch
NOTE: In water consumption is incl. both Paper Mill and Stock Preparation
- OptiCycle W and OptiFilter NF to purify PM’s clear filtrate to the level when it can be used instead of fresh water at certain applications - Microflotation for press section waters
