Membranes are used to purify drinking water, desalinate seawater and brackish groundwater, purify proteins, enzymes and bio-molecules, concentrate fruit juices, clarify and disinfect beer, wine and spirits, treat municipal and industrial wastewaters for safe discharge or beneficial reuse, and produce high-purity water for boiler feed, power generation and high-tech manufacturing.
Water Planet’s portfolio of membrane solutions meets the growing demands of industrial wastewater treatment and reuse needs with cost-effective solutions that return high quality water with minimal labor and maintenance.
What can membranes do?
How do membranes work?
Membranes offer a physical separation barrier with pores that range in size from micrometers through nanometers to Angstroms; hence, membranes offer the ability to separate large particles from small particles, large molecules from small molecules, metals and mineral ions from water and all of the above.
The key to success in deploying membrane technology is to select a membrane with a pore size small enough to achieve the desired separation, but as large as possible to minimize the energy demand (and operating cost) of the separation process. Also, it is important that a membrane does not encounter substances it was not designed to separate.
For example, RO membranes are the “tightest” or most selective water filtration membrane technology designed to remove salt ions from water; however, if RO membranes encounter bacteria, oil emulsions or colloidal materials they foul up very quickly, lose water production and require the system to be shutdown to enable chemical cleaning.
Frequent shutdowns and cleanings damage membranes and reduce their useful life. Therefore, if you have a challenging wastewater that ultimately requires RO treatment, UF membranes may be used in front of RO to remove the fouling substances. The increased capital expense to add the UF pre-treatment is often more than paid for by the operational efficiency gained by minimizing fouling, down-time, cleaning chemical consumption and membrane replacement.
What can membranes replace?
In water and wastewater treatment, MF and UF membranes are used in place of sedimentation and granular media filtration, which require large land-areas and chemical pre-treatment (coagulation/flocculation). Since the early 1990s, MF and UF membranes gained rapid acceptance and are now considered mainstream technology for removing suspended solids including bacteria, protozoa, clay particles, viruses, proteins and macromolecules. Nano-filtration and reverse osmosis technologies have replaced chemical softening, ion exchange, activated carbon and thermal processes for desalination and advanced water purification.
In industrial process separations, NF/RO technologies have largely replaced phase separations (distillation, extraction, etc.) and MF/UF have replaced conventional media filtration technologies. In either case, membranes typically offer higher selectivity, higher yield (less waste), lower energy demand and lower total cost of separation. Membrane materials and processes have been developed to selectively separate azotropic, racemic and chiral mixtures through combinations of solute-membrane affinity and the size of membrane pores. Membranes are used for laboratory analytical separations as well as product concentration, purification and sterilization in biotech, pharmaceutical, food and beverage and dairy industries.
What are the benefits of membrane technology?
In any application, once the influent and effluent compositions are known (or defined), a membrane can be selected to meet practically any separation need. Purified or concentrated product recoveries often exceed 98%. Membrane systems are generally more automated and smaller footprint (50-70% less space) than other separation processes. Automation allows (1) less operator attention, and automated alarms when attention is required and (2) in-place testing to quickly confirm that the membrane is not breached. Membranes separations take less energy than phase separations and last much longer than conventional media filtration technologies so that the total cost of separation is reduced. Some membranes have a useful life expectancy over 10 years.
What are the limitations of membrane technology?
Membrane technology offers a step-change in process separations efficiency and water treatment performance capabilities; however, the ‘Achilles heel’ of membrane technology is fouling.
Fouling clogs membrane pores increasing energy demand, cleaning frequency, process downtime, membrane replacement and operating costs.
At the same time this increases capital cost by requiring low flux operation (requiring more membrane area) and expensive pre-filtration and/or chemical conditioning.
Fouling is inevitable. What is required to combat membrane fouling?
- High-performance membranes
- Intelligent process controls
- Optimized process integration
Water Planet’s proprietary PolyCera® membranes were developed to extend the range of polymeric membrane filtration to the most challenging applications.
A fully automated, self-adaptive filtration process control software. It learns how the filter responds to the influent water quality to determine custom-optimized flux maintenance actions (i.e., backwash, CIP, regeneration, etc.).