Microfiltration & Ultrafiltration Integrity: Don’t believe breakages happen!

Myth spreads that a certain amount of MF/UF Fiber Breakages are acceptable...

I’m back, and I’m mad! I started this blog with the intention of being as informative and impartial as possible on water technology topics, but my New Year’s resolution is to spice it up a little and forget about being PC. I am fed up with the perceived mystique around building a reliable MF or UF system for drinking water applications after just losing out to Pall on a UF project because my company was considered ‘not qualified’ to have our price considered. I have to hand it to the ‘big three’ MF/UF manufacturers, Pall, Siemens/Memcor and GE/Zenon. They have certainly done a good job in convincing consultants and owners that manufacturing a MF/UF system is so complicated that only established players in the market should be considered. They were the first to get established in the market, so they have the right to leverage that advantage, but they can only pull the wool over the industry’s eyes for so long! There are now some bloody good alternative UF membranes out there on the market, better than most of the established products, and the sooner this is realized, the sooner the end users will reap the benefits.

In an interview for the project we were recently unsuccessful on, the owner’s consultant (from one of the biggest municipal engineering firms in the world) implied that because we were a small firm and did not have standardized UF system designs like our larger competitors, our custom designed systems would potentially have reliability issues because we did not have experience with the exact same system configuration operating in the field. He then went on to question why we did not have a large list of exceptions to the specification we bid to. The reason we didn’t have exceptions is because we bid with a design that matched the spec rather than tried to squeeze a standard UF skid design into their spec – duh! The big membrane companies have done a good job in brainwashing the engineers on why a standard design is better than a custom system for small skid mounted applications. The reality is that the big firms cannot cost effectively custom design a small skid mounted UF system and the only way they can be successful on these smaller projects is to have the smaller custom design firms disqualified. Good luck in now trying to put that square peg in a round hole and getting an off-the-shelf design to operate as specified!




Hollow Membrane Fiber Breakage

 Why then is our small company successful in winning similar sized NF and RO projects with the same global engineering firms? Is it because with NF and RO considered more of a commoditized market, the engineers assume these are simpler to build than MF/UF systems? As a company that manufactures UF as well as NF/RO systems, that is complete BS! UF systems are actually simpler to manufacture. The only challenge has been getting a UF membrane module that will not fail integrity tests. Two of the major MF/UF system manufacturers have had significant problems in recent years with membrane breakages, but they have done a very good job in convincing the market that some membrane fiber breakages are par for the course. Poppycock!! There are now UF membranes on the market from Toray and Inge that have no recorded fiber breakages to date, including systems we have built using these membranes. It is the established companies that manufacture their own proprietary MF/UF membranes that are having the integrity issues and want the market to believe that some level of membrane fiber breakages is inevitable (Stratton, et. al.). These companies are probably scared to death at the more robust UF membranes such as Toray’s that have entered the market and are available to OEMs (see Municipal Ultrafiltration Heads Towards Commoditization).

The large MF/UF system OEMs have largely left the packaged NF/RO market because they are not cost competitive, especially for skid mounted systems. Ultimately, they will not be competitive in the skid mounted UF market either – they actually aren’t currently cost competitive, but are surviving in this market through scare tactics to keep owners and engineers from considering the more cost effective alternatives. Sooner than you think, the time will come when at least two of the ‘big three’ will be squeezed out of the skid mounted MF/UF market. The big winners will be end users who will get higher quality UF systems at a much lower price.

References:

Stratton, Richard and Chang, Yujung (2011), “Membrane Fiber Breakage: Case Histories, Probable Causes, and Possible Solutions”, 2011 American Water Works Associations Membrane Technology Conference, March 28-31.

Municipal Ultrafiltration Heads Towards Commoditization

Market entry of Toray and Dow signal reign of 'Big Three' may be over!

The municipal market for ultrafiltration (UF) and microfiltration (MF) membranes has long been dominated by what the industry terms the ‘Big Three’; Siemens (previously US Filter), GE (previously Zenon) and Pall. Other players such as Koch and Aquasource, who made some early inroads into the North American market, have largely fallen by the wayside as inside-out PES UF/MF membranes have lost favor for various reasons. This has left the Big Three (B3) to divide up the North American UF/MF market, with other manufacturers rarely qualified to bid for these projects.

The dilemma for consultants and owners who want to purchase a UF/MF system is that the proprietary systems offered by the B3 each have their own unique characteristics. Therefore to create a competitive bid situation, at least two of the B3 need to be trialed to specify design parameters, unlike commoditized reverse osmosis (RO) membranes that can be bid on by a number of manufacturers after a single pilot study.

Finally, as Bob Dylan sang, The times they are a-changin’. The introduction of outside-in, PVDF UF modules to the market in the past few years by RO Membrane behemoths Dow and Toray has allowed OEMs, which have had a long relationship with these companies in the RO market, to now enter the UF market….and the timing could not have been better! I have been told by the larger engineering consulting firms that 5 years ago they would not have considered a UF OEM that did not have years of operating data from systems of comparable size to the project they were working on; that pretty much ruled out all but the B3. For various reasons including the consolidation of some of the B3 into larger more bureaucratic corporations, rising prices especially for smaller systems and some questions over long term membrane integrity for the submerged systems, many consultants are now willing to overlook previous experience requirements.

While the Dow and Toray UF modules are not interchangeable like their RO modules due to different positions of the feed and permeate ports (see Figure 1), availability is not restricted exclusively to a single OEM which allows more than one OEM to bid for a project using the same modules. This is the beginning of a huge change to the MF/UF market place, making bidding much more competitive and potentially allowing owners to conduct one pilot trial but still have multiple bidders as is the case for RO systems. This will be a relief to consultants and owners who in the past have had to endure expensive and lengthy pilot test programs to overcome the difficulty in comparing the proprietary MF/UF offerings.

Figure 1: Comparison of Toray and Dow UF Modules

Within a year of the Toray UF module receiving California Department of Public Health approval, several bids have been awarded to OEMs using this membrane and the first North American installation, a 2.0 MGD system built by Wigen Water Technologies, was started up in North Dakota earlier this year. This is the first of three UF systems between 1.0 and 4.5 MGD using the Toray module that Wigen is starting up in 2011. Wigen also has a 2.0 MGD system using the Dow module scheduled to start up in South Dakota in early 2012. At least two other OEMs have been awarded projects using these modules that are scheduled to start up in 2011.

So the times really are a-changin’ and the Big Three’s stranglehold on the MF/UF market is starting to weaken with the availability of quality PVDF outside-in UF modules to OEMs that are familiar with competing in the commoditized RO system market. While we are still not at the point of interchangeable UF modules from multiple manufacturers, the availability of the same UF modules to multiple OEMs will make the market much more competitive resulting in reduced costs for end users.

Is Suspended Ion Exchange (SIX®) Ready for Market?

In 2010 a new water treatment technology called Suspended Ion Exchange (SIX®) signaled its entrance into the North American water treatment market with presentations at several water industry conferences. SIX® was developed by PWN Technologies, a subsidiary of Netherlands based PWN Water Supply Company North-Holland, primarily as a pretreatment process for the removal of natural organic matter (NOM) prior to membranes.

PWN states (1) that SIX® overcomes limitations of traditional fixed bed ion exchange contactors, such as fouling and blinding of resin pores and surfaces with organic and colloidal matter, and is able to tolerate fluctuations in raw water characteristics. PWN also claims SIX® has advantages over the MIEX® Process, another suspended ion exchange process developed by Orica Watercare Inc., through improved efficiency of the ion exchange contactor and regeneration process while enabling the use of a range of commercially available ion exchange resins, unlike the MIEX Process which uses a proprietary resin.

Before I go any further, I will let you know that I did previously work for Orica Watercare and was involved in the development of the MIEX Process. As I no longer have any allegiances to my previous company, I will be making as impartial a review of SIX as possible. I believe my experience in the commercialization of the MIEX process also helps to provide a unique insight into the readiness of SIX for market.

How SIX® Works

Figure 1: Flow Diagram of the SIX® Process (Reference 2)

The SIX ion exchange vessel consists of vertical cylindrical contact chambers containing baffles and mixing paddles to distribute flow and ensure effective mixing. These continuous mixing chambers are used in series with the object of approaching the ideal contactor kinetics of a plug-flow reactor1. An anion exchange resin is injected into the raw water feed, suspended in the contact tanks and then removed after the second contact tank where it is regenerated in a separate regeneration process. The regeneration process consists of a number of mixed regeneration vessels where a brine solution is contacted with the resin. The brine solution is recycled a number of times to reduce waste volumes. Regenerated resin is then transferred to fresh resin tanks where it is then added back to the raw water feed. PWN has also investigated the use of Nanofiltration to separate NOM from the spent brine regenerant and further reduce waste volumes but the reported pilot results have only seen up to 67% removal of the NOM which would not allow the permeate to be suitable for resin regeneration (2).

The potential advantage of suspended ion exchange is that turbidity can pass through the contactors without impacting process operation, thus allowing SIX to be used as a pretreatment process. In addition, the efficient contacting of the resin in a plug-flow reactor configuration and subsequent ‘exsitu’ regeneration can potentially result in significantly lower brine waste volumes compared to conventional fixed bed ion exchange systems.

This background information has been gleaned from papers and presentations I attended at the 2010 IWA Leading Edge Technologies Conference and the 2010 AWWA WQTC Conference. No additional information is readily available on the process, with little detail on PWN’s website. It is therefore difficult to make a proper quantitative assessment of the true benefits of SIX and the readiness of the technology for market. The kinetic modeling that has been performed is excellent and demonstrates that the plug-flow reactor configuration is a more efficient means of facilitating ion exchange – but most chemical engineers could have told you that without the testing. Reported percent removals of NOM and nitrate are all based on testing performed on one water source. I would like to see more testing conducted on different water sources with a range of characteristics, including different NOM characteristics and ionic compositions, for a better indication of the robustness of the process.

Show me a Mass Balance!

My major beef with the available data is the absence of any mass balance data to quantify claims of regeneration efficiency, low waste volumes and low salt use. The data presented at the IWA Conference just didn’t add up. Dissolved organic carbon (DOC) concentrations in the waste brine were reported only as ‘greater than 300 mg/L’. How much greater… 350 or 500 mg/L?? There was no quantification of how much waste is produced and when I asked the presenter, a PWN representative stood up and said it was about 1 m3 per 5000 m3 treated. That is 200 gallons of waste per 1000 gallons of water treated - pretty impressive, but let’s look again at the waste TOC concentration to see if that makes sense. Assuming the waste TOC concentration was 400 mg/L in 1 m3 of waste; by mass balance the process is removing 400 grams of TOC per 5000 m3 of water treated, or 0.08 mg/L – not very impressive considering the raw water TOC was reported at about 6.0 mg/L. The IWA paper shows a DOC reduction by SIX of about 3.0 mg/L, which from my experience with anion exchange is reasonable. By mass balance, if the waste DOC concentration is 400 mg/L, the waste volume should therefore be more of the order of 37 m3 per 5000 m3 (7,500 gallons per million gallons of water treated) – unless the SIX process is also eating DOC…..


Figure 2: SIX® Pilot Plant (Reference 2)

My final concern is the regeneration process. It looks complex to me (Figure 2). Claims that this is simpler than the MIEX process are outdated by about 6 years. Significant enhancements have been made to the ‘exsitu’ regeneration process used by the MIEX technology since the first full-scale system started up in 2001 resulting in substantial reductions in waste volumes and simplification of operation. SIX still has to go through this learning curve and the sooner PWN can get a continuous demonstration plant operating the sooner it can start to iron out the operability bugs that will inevitably be found.

Despite my above reservations, I think SIX has great potential but it will be a few years yet before the technology is ready for widespread adoption. It would be great for the water industry if the MIEX technology had a truly competitive suspended ion exchange process to drive down costs to customers, speed up process improvements and allow ion exchange pretreatment to be competitively bid. This would be similar to when Memcor developed its submerged membrane process to counter its erosion of market share by Zenon’s Zeeweed process in the late 1990’s. To successfully launch SIX in North American, PWN should take a look at how the MIEX process was brought to market, including initiating pilot studies on a number of different water sources with the participation of locally respected academics and consulting firms and establishing a full-scale demonstration facility ASAP!

1. Friend-Gray, O.P.; Malley, J.P. Jr; “Suspended Ion eXchange (SIX®) for Pre-treatment in Advanced Oxidation and Membrane Water Treatment Systems”, Proceedings of IWA Leading Edge Technologies Conference, Phoenix AZ, June 2010.

2. Friend-Gray, O.P.;”Optimization of the Suspended Ion eXchange (SIX®) for Pre-treatment”, Proceedings of the AWWA Water Quality Technology Conference, Savannah GA, November 2010.

Industry Trade Shows: Pot of Gold or Money Pit?

Are you stuck in the tradeshow rut, spending most of your time chatting to your neighboring exhibitor, catching up on your voicemails and wondering if there are potential leads wandering past your booth? Do you find yourself doubting if all of the time and expense you put in to exhibiting at trade shows is worth it? Is the only reason you are there because you want to support your local sales rep or because you fear your ‘noticed absence’ will hurt your reputation? I want to let you in on something – trade shows are an extremely valuable opportunity to strengthen existing customer relationships and to bring in quality new leads – but you only get out of a tradeshow what you put in!

Fishin’ without bait…

If you think all you need to do is turn up to the show with your booth and literature and the leads will flow in, you’re dreamin’…. This is like fishing without bait. You may be extremely lucky and hook an unsuspecting fish passing by but… more than likely you will have plenty of time to get to know your neighboring booth buddies and keep on top of your emails. And you are not the only one in the boat. At most regional water industry shows that I go to, I hear the same complaint from my fellow exhibitors …the show was dead… the organizers didn’t do enough to get people into the hall…there were too many competing events….we had a horrible spot in the hall...” So you think all you have to do is pay for your booth space and you should be guaranteed a flood of quality visitors to your booth?” If that is the case, save your money and don’t bother exhibiting!

In contrast, my booth neighbors will say to me “Wow you sure had a lot of traffic at your booth…you’ve hardly had time to blink!” These neighbors have also made the aforementioned complaints when I have been located in the same dead spot in the hall! So how did I get that much traffic when all the booths around me were dead? There are a number of reasons, including having an eye-catching display and planning activities during the show to direct people to my booth, but by far the biggest factor in generating traffic to your booth is pre-show marketing! I cannot emphasize enough the importance of putting in some effort before the show to draw people to your booth. If you don’t have time to do this don’t go! Here are a few suggestions for pre-show marketing that can really help you get a return on your tradeshow investment:

Pre-Conference Mailer

A pre-conference mailer can be a relatively inexpensive marketing tool for regional trade shows. Prior to the national trade shows you can be bombarded with incentives to visit booths but very rarely do attendees receive this type of marketing leading up to the regional shows – so here is an opportunity to get noticed. Most conferences offer pre-show registration lists to exhibitors at no cost. Take advantage of this list and mail a booth invitation directly to attendees. Personalize the letter as much as possible and it helps if you add an incentive to visit the booth such as a business card drawing for a prize if you are doing a mass mailing or a direct exchange of the letter for a gift for a very targeted mailing. One of my most successful pre-show marketing efforts was for a show in South Carolina several years ago. At the time I was selling a water treatment process that removed a particular contaminant. I went through the EPA register and compiled a list of every city in the state in violation of the relevant regulation and sent them an invitation to the booth to find out about our process. Almost 50% of the invited cities visited the booth!

Pre-Arranged Meetings

Don’t expect to turn up at the conference and be able track down attendees to arrange meetings. The consultant you want to see is probably being pursued by other manufacturers while she is also trying to meet with water utilities who are her customers. Let’s face it, in the water industry we manufacturers are at the bottom of the importance food chain, even though we provide the technology. So we need to be very organized in planning our meetings. Make appointments prior to the show before your target customer has a full dance card. If you have the pre-show registration list, use it to help set up some meetings in advance, or at the very least, get people to meet you for a short while at your booth.

Pre-Show Advertising

Pre-Show advertising is not cheap (you can do a lot of direct mail for the price or one ad) but if you have the budget, many trade journals have pre-show issues where if you advertise you can get a free product spotlight. On your ad you will also have your booth number advertised. At a previous company, prior to our first national trade show as part of our launch into the U.S. market, I developed a preshow marketing campaign using an eye catching jumping goldfish in direct mail and in preshow trade journal advertising. Even though we had a small booth at the back of the hall, we almost always had a queue of people in front of the booth wanting to find out about ‘that company with the cute goldfish’.

Got the Message?

Don’t waste your time and just show up to the next trade show. American Water Works Association (AWWA) surveys show that over 80% of people visiting their annual water industry show participate in purchasing decisions and over 30% intend to purchase equipment from exhibitors in the next 12 months. Pre-show marketing can help you find those people who are looking for your product and let you get a step ahead of your competitors. Try it once and your time invested will be repaid many times over!

Ceramic Membranes: Mainstream or niche low-pressure membrane player?

Ceramic membranes have been a hot topic at recent American Water Works Association (AWWA) and International Water Association (IWA) conferences. In more and more cases, ceramic membranes are being piloted alongside polymeric membranes in technology evaluations for new water treatment plants. Claims from manufacturers such as NGK–MetaWater of higher fluxes, a greater tolerance to foulants and particulates and no membrane replacement for the life if the facility, has drawn much interest from the most conservative of consulting firms.

I have been involved in a few pilot studies that have included ceramic membranes and there is no doubt that the technology is effective. The claimed advantages also seem to be valid. But are ceramic membranes an economically viable alternative to low pressure polymeric membranes? Why are there still not any installations in the United States?

History of Ceramic Membrane use for Drinking Water
NGK Insulator, Ltd., traditionally a manufacturer of ceramics for the automotive, power and electronics industries, began research into the development of ceramic membranes for drinking water treatment in the early 1990s. In 1996, NGK began production in Japan of the first commercial ceramic membrane water purification systems and installed the first small-scale system. In 2008, NGK and Fuji Electric merged their water businesses to form Metawater Co., Ltd. whose product range focused on NGK’s ceramic membranes and Fuji’s ozone generation systems. As of December 2009, NGK-Metawater had installed 76 ceramic membrane systems in Japan. Most of these are very small, with only eight systems over 1-MGD capacity and the combined capacity of these eight systems around 28-MGD (Freeman, et al), although the MetaWater website indicates that the combined capacity of systems installed and under construction is 112 MGD. Outside of Japan, there has been virtually no adoption of ceramic membranes in drinking water treatment, although according to Kruger Inc. who has the rights to NGK-Metawater’s ceramic membrane technology in the United States, there are two systems currently in design in the U.S.

How Ceramic Membranes Work

The ceramic membranes used for water treatment are made from aluminum oxide and are tubular, similar to hollow fiber polymeric membranes, but with a much larger diameter (Figure 1).


Water passes down the parallel tubes from the feed inlet to the outlet end face. The surfaces of the tubes are coated with a ceramic membrane material that has a uniform pore size to provide microfiltration or ultrafiltration. The feed stream is introduced under pressure at the inlet end face and is withdrawn as retentate at the downstream end face. Permeate passes through the membrane into the porous monolith ceramic structure. The combined permeate from all of the tubular passageways flows through the monolith support to permeate conduits within the monolith that transport the permeate through slots to an external collection zone (Figure 2).

Figure 2: Schematic of Ceramic Membrane Operation (Source: Kruger Inc.)

Pros and Cons of Ceramic Membranes
Two presentations by Freeman, et al and Kommineni, et al at the 2010 AWWA Annual Conference in Chicago provided information on side by side pilot study comparisons of ceramic and polymeric membranes and some independent insight into the advantages and disadvantages of ceramic membranes.

The major advantages of ceramic membranes are as follows:

• Longer Membrane Life: There are no membrane fibers to be broken so the membrane life should be significantly longer than polymeric membranes and maintenance requirements significantly less. MetaWater claims that no membrane elements have needed replacement since the first system was installed in 1996.
• Easier to Clean: The high mechanical strength of the membranes allows aggressive cleaning regimes with acids, alkalis, oxidants, high temperatures and high backwash pressures to recover membrane performance. The membranes can therefore tolerate high foulant and particulate loadings. Chemical cleaning frequency is only 2 to 6 times per year.
• Higher Flux: Ceramic membranes can be operated at flux rates over 100 gfd and reportedly as high as 175 gfd compared to polymeric membranes which are typically operated in the range of 40 to 60 gfd (Freeman, et al). Less membrane surface area is therefore required to provide a given throughput.
• Higher Recoveries: Less frequent backwash cycles and shorter cycles result in recovery rates of around 98% for ceramic membranes compared to 90-92% for polymeric membranes.

Looking at these advantages you would wonder why there isn’t wide adoption of ceramic membranes for drinking water treatment. Well there is one important factor that needs to be considered – the cost! In the pilot study reported by Freeman, et al, ceramic membrane capital costs were of the order of 2 to 2.5 those of polymeric membranes. Taking into consideration the additional membrane replacement cost for polymeric membranes, the present worth (20 years @ 6%) for ceramic membranes was still twice that of polymeric membranes. If the feedwater had a high particulate loading or required activated carbon dosing, the added costs from additional pretreatment required for polymeric membranes did narrow the present worth difference somewhat.

As the water industry is also conservative, and understandably so where ratepayers’ money and health are at stake, there is also some reticence to recommend this relatively new technology without a better understanding of long term membrane life and long term fouling characteristics. Both presentations also indicate that limited supplier options in North America are a concern.

So a mainstream or niche technology?
With Kruger’s sales and marketing reach in North America, I am sure there will be ceramic membrane installations outside of Japan in the not too distant future, but… while ceramic membranes are very effective at providing drinking water filtration, unless initial installation costs can be significantly reduced, it will remain a niche technology. The niche will be limited to drinking water sources that are difficult to filter with polymeric membranes (high particulate and organic levels) and would otherwise require significant pretreatment. Remote systems may also benefit from the significantly longer membrane life and lower maintenance requirements. Outside drinking water applications, I see much more potential in applications such as wastewater recycling and recovery of oil and gas produced water.

Freeman, S; Henderson, R; Delphos, P; Clement, J; “When are Ceramic MF/UF Membranes Cost-Competitive with Polymeric MF/UF”, Proceedings of AWWA Annual Conference and Exposition, June 20-24, 2010, Chicago IL

Kommineni, S; Hoffman, R; Karnik, B; Stringer, C; DelRegno, K; Myers, N; “A Collaborative Evaluation of Ceramic Membranes – An Emerging Water Treatment Technology”, Proceedings of AWWA Annual Conference and Exposition, June 20-24, 2010, Chicago IL