Integrating membrane filtration forwater reuse in tissue mill

Water is an essential and indispensable component is the pulp- and paper production industry.The increase in energy costs, stricter environmental regulations and water resource shortageshave caused a reduction of the water footprint in the industry as well as an increase in waterrecycling and water circuit closure. Reducing water usage requires an understanding of wherecontaminants originate, as well as which streams are critical to the process and how they impactmill operation. The recirculation of water can cause contaminant accumulation; therefore millsemploy technologies for water treatment in the internal water cycles, the so-called ‘kidneys’.Application of membrane technology is one such option which can improve the recycled waterquality and reduce contaminant buildup.The present study was carried out on a lab-scale for the treatment of a tissue mill effluent usingmembrane separation. A combination of pretreatment methods and various membranes werecompared with regards to separation, flux and fouling. The AlfaLaval M20 device was to treatwastewater samples sent from the mill, where the permeate was recirculated to the feed tank.COD and TOC levels are compared with regards to determining the separation efficiency. Thepermeate flux was measured over the two-hour filtration period, as well as flux recovery todetermine fouling levels. Additionally, some economic aspects of the process are discussed.This study suggests the potential application of a combination of flocculation or centrifugationpretreatment, with reverse osmosis membranes for recycling water to replace freshwater intake.The results also indicate the possibility of using ultrafiltration as kidneys to decreasecontamination buildup for further water loop closure