Pulp and paper producers can use a compact, pilot-scale membrane ultrafiltration (UF) plant to streamline evaluation of different process designs and membrane materials for effluent-control processes such as paper-coating removal, de-inking, whitewater recycling, and COD reduction. Offered by PCI Membrane Systems Inc., the unit has an automatic data-logging feature that frees operators from having to manually record temperatures, pressures, and flow rates. Operators can define set points either through a personal-computer interface, or remotely through a dedicated phone line.
The Single-Stage UF Pilot Plant from PCI operates either in batch mode or continuous "feed-and-bleed" mode. In feed-and-bleed mode, the operator enters set points to individually control the feed-pump flow volume and the volume "bleeding" out of the retentate line, allowing different effluent concentrations to be created across the membrane surface.
Depending on the characteristics of the process fluid, the pilot plant can operate over a wide range of volumetric concentration factors (VCF) between 1.25 and 50. During operation, an integral heat exchanger can maintain the temperature of the process fluid up to the 175°F operating temperature commonly encountered in pulp and paper applications.
The tubular membrane modules the pilot plant uses, are said to be particularly effective for high-solids fluids, since tubular designs create a turbulent, self-cleaning flow along the membrane surface, which minimizes fouling. PCI can configure the pilot plant with any of three different designs from its range of standard modules, or develop custom membranes to suit specific processing requirements.
Pulp and paper producers generally use the Single-Stage UF Pilot Plant to help develop large-scale processes that either recover valuable process products or reduce the amount of waste material in discharge effluent. In one example of the latter at a large pulp mill, two pilot plants allowed PCI to develop membranes specifically suited to the mill's hardwood and softwood effluents, leading to a full-scale plant installation and a successful start-up of what became the world's largest membrane filtration system of its kind.
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