University of Minnesota
Minnesota Technical Assistance Program

Membrane Filtration Systems

Membrane filtration can recover valuable materials from waste streams that are not recoverable using standard filters, such as cartridge or sand filters. Typical particle filtration uses a porous barrier to separate substances based their state of matter, gas, liquid, or solid. Examples include removing dust and paint from air, or removing solids from wastewater.

Membrane filtration separates materials based on their size, regardless of the state of matter allowing for separating without the addition of an energy intensive and expensive phase change process, such as evaporation or distillation. The ability to retain particles or molecules that are small enough to pass through an ordinary filter is the key advantage of the membrane filtration system. As an example, a solution of dissolved sugar in water can be separated into sugar and water by applying pressure across a membrane designed with the proper pore size for the sugar.

After separation the concentrate, rich in particles or molecules becomes less expensive to dispose of and the permeate, usually purified water, can often be put back to use in the process. As an example, membrane filtration may be considered for the treatment of wastewater if you would like to recover product or process chemicals that are currently going down the drain, or if you have high oxygen or solid loading.

Membrane filtration is a general term that covers a variety of separation technologies including reverse osmosis (RO), nanofiltration, ultrafiltration and microfiltration. Each technology is effective within a range of molecule/particle sizes. The figure below shows how the membrane filtration technologies compare.

RO Membrane Filtration Example

Membrane FiltrationTraditionally in maple syrup processing all of the water in sap is removed by evaporation, known as dewatering, which is energy and cost intensive. To reduce the cost of dewatering, many maple syrup producers concentrate the sugar solution using RO.

RO applies pressure across a membrane. The water molecules in the solution pass through the membrane, but the sugar molecules cannot because they are too large for the membrane pores. This results in a concentrated sugar solution and a water stream mostly free of sugar. RO allows 75% of the water to be removed from the maple sap before it is sent to an evaporator. Removing the majority of the water with RO reduces energy costs for evaporation by about 60%.


Manufacturers and Suppliers of Membrane Filtration Equipment

MnTAP maintains the list of membrane filtration equipment manufacturers and suppliers below solely as a service to Minnesota companies. This is not a complete list of available manufacturers or suppliers and does not represent an endorsement by MnTAP. By providing the list, MnTAP does not guarantee that the products do or do not comply with environmental and safety laws in any specific application.


Local Representative

Equipment Type

GE Osmonics
Minnetonka, MN

Filtra Tech Systems, Inc.
Shakopee, MN
952.988.9600 | 800.783.4955

Microfiltration, ultrafiltration, reverse osmosis

Clarence, NY


Microfiltration, ultrafiltration, nanofiltration

Koch Membrane Systems
Wilmington, MA


Microfiltration, ultrafiltration

PCI Membrane Systems Inc.
Zelienople, PA

Lewis Pain

Microfiltration, nanofiltration, reverse osmosis, ultrafiltration

Sanborn Technologies
Walpole, MA


Nanofiltration, ultrafiltration


PFC Equipment, Inc.
Maple Grove, MN


Microfiltration, ultrafiltration

#5 | 10/2008

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