Guest Column | September 10, 2015

Will Zero Liquid Discharge Save Forward Osmosis?

By Paul O’Callaghan and Dr. Graeme Pearce

While increasing patents indicate potential forward osmosis (FO) applications that may generate opportunities for new FO products, a new BlueTech Research Insight Report explores the reasons why FO remains a niche technology.

Forward osmosis technology has steadily progressed in the past few years towards a number of niche markets, but it faces difficult challenges on the road to commercialization.

After several decades of modest uptake, reverse osmosis has become fully mature in the last 15 years, and is now widely adopted. Several established membrane manufacturers have almost identical products in terms of dimensions and performance.

By contrast, FO to date has mainly been the domain of smaller, often venture-backed, players, such as Trevi, Oasys, Modern Water, Porifera, and Hydration Technologies Inc.

The larger players in the membrane industry have mostly watched from the sidelines. Dow, Toray and Hydranautics, all leaders in RO membranes, are visibly absent from the FO world.

A recently completed study by BlueTech Research explores the reason for their absence. How do these larger companies see FO? Do they view it as “playing in the sandbox” or a technology with real potential? The incumbents in any industry — also true of RO — are generally focused on sustaining innovation, limiting discontinuous or disruptive innovation to new entrants in the business.

The BlueTech investigation also explored the status quo in this area of technology, specifically interested in which applications in which FO might make sense and whether it will niche technology or eventually affect the mainstream market?

The authors of this report interviewed leading membrane figures and innovative companies active in the water industry. Additionally, they completed a literature review of existing papers and an analysis of the patent landscape.

There are many variants of FO depending on the separation’s objective, and, as a result, there are multiple terms used such for this — direct osmosis, osmotic dilution, concentration — but the generic term (acronym) FO will be used here.

Commercialization At Early Stage

Despite years of development, the technology has only recently been seriously considered for commercial development, and uptake is still in its infancy. The technology is still largely at the pilot or demonstration stage and, in terms of market adoption, it is in the domain of innovators.

However, a review of recent conference papers shows that interest in FO is now acute; many scholarly papers and newly formed membrane and system suppliers now warrant multiple conference sessions on this technology.

For example, Steve Gluck, fellow with the U.S. company Dow Water & Process Technologies, will be leading a session on FO technology at the 2015 Water Environment Federation’s Technical Exhibition & Conference (WEFTEC). Modern Water’s Peter Nicoll co-chaired a session on FO at the International Desalination Association’s world congress in early September 2015.

This latter session showed the likely ways forward for FO as it seeks to find niches in the water and wastewater industry. These usually involve combining with other technologies to further refine the reject of existing process or to deal with more difficult waste product water. In the IDA sessions, papers covered FO with RO, ultrafiltration, multi-effect distillation and membrane bioreactors. Many of these developments are driven by the search for the reduction in brine volumes and potentially for zero liquid discharge (ZLD).

So what are the challenges faced by FO as it strives towards commercialization? Firstly, there is the issue of membrane fouling.

Membrane Fouling And FO

In RO and membrane filtration, the feed side of the membrane faces a fouling challenge, while the reverse side is only in contact with the filtered permeate product. Even if the flow is reversed, for example in a backwashing process, the purified stream has no potential for fouling.

In FO, fouling occurs on both sides of the membrane due to the possibility of particulates and other foulants on the feed side, and the highly concentrated draw solution on the permeate side. This situation may cause concentration polarization. Different solutions have been used in an effort to ameliorate membrane fouling, but none is universally accepted, and the first commercial products have used widely different membrane chemistries and structures.

For some FO applications, feed-side fouling may present the greatest challenge, whereas, for others, depending on the treatment objective, the greater challenge may be on the permeate side. Currently, most commercial products are based on the spiral wound concept used in RO, but there are also products based on plate-and-frame designs and hollow fibers. This diversity underlines the fact that there is no universally accepted route to overcome the technical challenge, an aspect the report analyses in detail.

Increasing Patents From Diverse Sources

It is interesting to see some of the players that hold significant IP positions, in terms of numbers of patents, relating to FO. Figure 1 indicates a steady increase in the number of published research papers in the area of FO over the past five years, with a 60 percent increase between 2012 and 2013.

Figure 1. Annual Number Of Forward Osmosis Research Papers Published

Source: BlueTech IP Watch™

Figure 2 illustrates consistent annual increases in the number of FO patents granted between 2009 and 2014. This is certainly an indication that there is the potential for IP generation in this area, and that universities and private companies see value in building IP positions in this area.

Figure 2. Annual Number Of Forward Osmosis Patents Granted

Source: BlueTech IP Watch

The patents are coming from a very diverse range of sources including Oasys (7 percent), Yale University (7 percent), National University of Singapore (7 percent), and University of Reno Nevada.

Failure To Surmount Hurdles

FO is a promising technology, but it presents a difficult set of technical hurdles and has so far failed to make a significant commercial impact. However, recent interest has grown sharply from both academia and several specialized companies, and there has been good progress in addressing the challenges. Several attractive application niches are now developing which could present an ideal opportunity for diverse product offerings from specialized suppliers.

BlueTech’s research has provided a comprehensive guide to where the technology sits in today’s water and wastewater industry and where it might go from here.

About the Authors:

Paul O’Callaghan is the founder and CEO of BlueTech Research.

Dr. Graeme Pearce, director of Membrane Consultancy Associates Ltd and affiliated to O2 Environment’s Technology Assessment Group, is a membrane technology specialist with more than 30 years of experience in the industry and the author of the Insight Report on Forward Osmosis*.

*The Insight Report on Forward Osmosis was made available to BlueTech clients in August 2015. For more information, visit or contact