Water and Fluid Separation News

Sterlitech is pleased to offer a “plug and play” DCMD test cell. The first commercially available bench-scale cross/tangential flow test cell, that mimics conditions representative of large-scale DCMD systems with minimal amounts of membrane or product. This offers researchers fast and accurate performance data to easily evaluate the performance of membranes and/or the membrane separation processes.

“Adding the DCMD test cell to the Membrane and Process Development product line complements this line of product by offering researchers a bench-scale cross/tangential flow test cell for evaluating Temperature-Driven membrane separation processes,”
- said Sepideh Jankhah, Product Manager at Sterlitech Corporation.

How it works: the liquid to be treated is circulated in direct contact with the feed side of the membrane in the Sterlitech’s DCMD cell. A cold liquid solution is circulated in direct contact with the permeate side of the membrane.

Sterlitech is launching new stir bar assemblies for the HP4750 family of stirred cells. The new design has the following features and benefits:

• A strong magnet for better mixing
• Secure design to eliminate the risk of damage to membrane
• Complete disassembly for cleaning
• Composed of chemical resistant PTFE and SS316 parts

Stir bar assemblies are commonly used in dead-end filtration cells, such as HP4750, HP4750X, to induce turbulence at the membrane surface in order to reduce the membrane fouling. To browse our complete selection of stirred cells, parts and accessories, please visit https://www.sterlitech.com/stirred-cells.html

Researchers from the European Monitoring Center for Drugs and Drug Addiction are zeroing in on public toilets in Europe to identify drug use patterns across the continent. Over the past decade, sewage plant wastewater has been a top source for monitoring drug consumption. However, due to the rising number of new psychoactive substances on the market, scientists have had to come up with new ways to identify suspicious chemicals more effectively. In a recent publishing entitled “Assessing illicit drugs in wastewater”, the EMCDDA expounds on new methodologies for scanning through sewage water to identify drug use trends in different cities. Part of the report includes references to studies that sourced and analyzed wastewater directly from public toilets where drug use was thought to be common. According to the paper, this technique allows researchers to carry out more geographically detailed analyses as well as identify drugs whose uses are still unknown. Through the traditional

What is silt density index (SDI)?
Silt density index (SDI) estimates the quantity of suspended solids and colloids inside of water. SDI is measured following the ASTM D19.08 Standard Test Method for Silt Density Index (SDI) of Water, using a 0.45 micron membrane. SDI provides information about the fouling potential of water treatment equipment, including membrane filtration systems, and therefore is commonly used in their design and choice.

Is SDI a reliable fouling propensity parameter? How is it used?
SDI is a simple and helpful tool extensively used in pilot or large-scale treatment plants as a standard test to verify the fouling potential of RO and NF membranes. However, using SDI to estimate the fouling intensity of water treatment equipment has some limitations. Even though SDI is measured using a dead-end filtration unit, hydrodynamic conditions in dead-end filtration units are not representative of the hydrodynamic

 Q: What is Cross Flow Velocity?  

A: Cross flow velocity (CFV) is the linear velocity of the flow tangential to the membrane surface and is reported in [m/sec] or [ft/sec]. CFV affects the hydrodynamic conditions in the cell, and as a result affects the fouling rate and formation of concentration polarization at membrane surface and is calculated by dividing the volumetric flow rate [lpm or gpm] in the flow channel by the cross sectional area [m² or ft²] of the flow channel.  

Q: How is CFV calculated in Sterlitech’s bench-scale test cells?  

A: Example: Calculate CFV in the CF042 cell  

• Flow channel cross sectional area: Channel depth x Channel width* = 0.23 x 3.92 cm

Sterlitech teamed up with Senior Engineering Students at California State Polytechnic University, Pomona (Cal Poly Pomona) to evaluate the design of a tangential flow Air Gap Membrane Distillation (AGMD) test cell. Membrane Distillation (MD) is a thermally driven membrane separation technique used for desalination. In this process, the driving force is the difference in the vapor pressure on both sides of the membrane, where permeate travels through a hydrophobic membrane in a vapor phase. Advantages of MD process over conventional distillation or pressure driven separation processes are:

• Low Operating Pressures
• Low Operating Temperatures
• Less Susceptibility to Fouling

These all translate to lower energy requirements that make MD an energy efficient separation process. Scope of the Project: A bench-scale tangential flow test cell is configured in this project where feed solution is circulated tangentially

North American Membrane Society (NAMS) annual meeting was held in Bellevue, WA, during the last week of May. Due to the great collective interest shown by the membrane research community, only 40% of the abstracts submitted to the meeting could be accepted for podium presentation, which made up to about 140 talks! In addition, about 140 posters were presented in 5 parallel poster sessions. As a comparison, there were about 144 talks and 160 posters in NAMS 2015 meeting at Boston. Conference attendees were primarily researchers from industry and academia.   Research was focused on the following topics:

• Membrane Distillation (MD)
• Biomimetic membranes
• Desalination and potable water production
• Gas separation
• Design and processing of polymeric and inorganic membranes
• Designs and processing of composite and hybrid membranes
• Novel membrane materials

Other topics

Nanostone flat sheet membranes are being discontinued by the manufacturer. Limited quantities of Nanostone flat sheet membranes is available at the moment, for more information or if you need assistance finding a suitable replacement product, please contact Sterlitech at [email protected].  

Nanostone™ Discontinued Nanofiltration Membranes

Series	NF4	NF8
Applications	Partial Desal, Sulfate Removal	Partial Desal
pH Range	3-10	3-10
Flux (GFD/psi)	46/150	77/150

Nanostone 1812 Elements are being discontinued by the manufacturer. If you need assistance finding a suitable replacement product, please contact Sterlitech.   You can browse other 1812 elements that Sterlitech offers at the moment by clicking here.   Limited quantities of Nanostone Flat Sheet Membranes are still available; please contact us for more information.

Forward Osmosis has been known and exploited as a separation process for a variety of applications including water and wastewater treatment, food processing, and power generation since the early 1960’s. Can this process also be applied for air de-humidification? Recent publications and patents have demonstrated that combining capillary condensation with osmosis separation through a semi-permeable membrane, introduced as Osmotic Membrane Dehumidification process, can be an efficient de-humidification method.

In the Osmotic Membrane Dehumidification process, a humid air stream is brought into contact with a semi-permeable membrane, which separates the air stream from an osmotic solution, i.e. draw solution (draw solution is generally a salt solution). Water vapors in the air stream condense by capillary condensation in the pores of the membrane and the condensed water is transferred into the draw solution by osmosis.

Unlike the conventional de-humidification processes,