These are the initiatives we currently have ongoing in the Ladner research group.

Regenerable membranes
Fouling (a buildup of organic matter or other material that decreases productivity) is one of the most significant drawbacks to using membranes for water treatment. Membranes can be cleaned to remove the foulants, but rarely can they be cleaned completely. This project seeks to develop a new kind of membrane with a “regenerable skin.” The skin can be shed after fouling and a new skin can be applied to give a perfectly fresh membrane. The big question is what do we use for the skin and how do we attach it and release it. As part of this effort we are trying to find coatings that can adsorb low-concentration pollutants like endocrine disrupting compounds, pharmaceuticals, and personal care products.

Helical-flow reverse osmosis modules
In an effort to reduce fouling and energy consumption in reverse osmosis, we have envisioned a new kind of module. It is similar to current state-of-the-art spiral wound modules, but the spacer between the membranes causes water to flow in a helical path, the geometry of which can be adjusted to give maximum water productivity per energy input. Also, fouling is far less likely in the new flow channels than it is in the standard module. We are beginning bench-scale work as well as computational fluid dynamics (CFD) modeling to determine the usefulness of our concept.

Wind-powered desalination
We are working with a small business, Windation Energy Systems, in California, to couple a wind turbine directly to a reverse osmosis desalination unit. This involves the redesign of the RO system to accommodate low-intensity and intermittent wind. Bench-scale lab experiments as well as modeling of the system are both planned.

Algal biofuel separations
Much of the algal biofuel research currently ongoing is geared toward selecting and modifying strains to increase their lipid content. However, harvesting the algae (removing them from the water they grow in) is a key bottleneck in making algal biofuels sustainable and this is receiving much less attention. We are interested in determining the fundamental properties of the algal cells that affect the energy input required for harvesting. Our focus is on microfiltration and ultrafiltration membrane processes which show great promise for providing the needed separations, especially for the smallest microalgae that have the highest growth rates and lipid contents. The expected end result is to redesign the filtration system to enable low-energy harvesting which will help make algal biofuels viable and sustainable.