When the U.S. Food and Drug Administration began implementing the tightened animal feed rules in its Food Safety and Modernization Act in September 2016, U.S. Water Services had to reformulate its entire product line of corrosion and scale inhibitors. None of the 300-plus products would be approvable under the new regulations. “We had to come up with new products,” says Mitch Manstedt, strategic business leader for U.S. Water, a Minnesota-based industrial water treatment solutions provider. “So we’re dealing with some very stringent guidelines here.”

Overhauling products designed for biofilm control in the biofuels industry was a huge undertaking for most chemical and service providers in the wake of the FSMA regulations, Manstedt says. The rule effectively eliminated the use of nonoxidizing microbicides in plants complying with the FSMA rules, out of concern for the contents of distillers dried grains. “Anything that could end up in DDGS which might be used for animal feed has to be approved as either a potable water treatment, or FDA approved as an animal feed additive, or safe to use in animal feed through a GRAS (generally recognized as safe),” says Jim Lukanich, director of applied technology for U.S. Water. For nonoxidizing microbicides, that GRAS branding isn’t likely, he adds.

“What we’re left with are programs using oxidizing microbicides only,” Lukanich says. That leads to challenges, as nonoxidizing microbicides—such as quaternary ammonium compounds—are more effective than oxidizing microbicides—such as chlorine, bromine and chlorine oxide—at penetrating into biofilm to kill the bacteria within. “The effectiveness of oxidizing microbicides relies on staying ahead of biofilm accumulation,” Lukanich says.

Even with strict regulations, chemical and service providers are finding ways to detect and remove biofilm, limiting negative effects such as fouling, corrosion, overall inefficiency, continued infection and, in some instances, costly cleaning.

Biofilm Formation
“There are many things that biofilms can possibly affect in an ethanol plant,” says Wayne Mattsfield, scientist for Phibro Ethanol Performance Group. Biofilm is essentially a protective layer formed by bacteria that have attached themselves to surfaces in wet environments, such as cooling towers, heat exchangers or distillers. “Bacteria tend to attach to surfaces, rather than free flow,” Mattsfield says.

Because of their rural locations, generally close to agricultural operations, ethanol plants are at high risk of bacterial contamination. Ethanol cooling plants tend to have a higher level of airborne contaminants, dust, and dirt and plant debris than other cooling systems, such as a hospital’s, Lukanich says. “The cooling towers operate in an environment that is more opportunistic for those contaminants to get into the cooling water, resulting in a perfect scenario for biofilm growth.”

Once attached to a surface, bacteria begin to form an exopolysaccharide layer—biofilm. The biofilm offers protection from chemicals and disinfectants, and acts like an insulation, reducing the ability of cooling water to cool the fermentation process.

Interestingly, the biofilms also communicate with their bacteria hosts. “The biofilm almost acts like an organ and it brings nutrients into the center of the biofilm and waste products can be excluded from the biofilm,” Mattsfield says.

Biofilms also provide gradients within the buildup of biological material, he says, specifically with oxygen. The most oxygen is retained in the outer layers, leaving a completely anaerobic environment closer to the surface the bacteria have attached themselves to. “Anaerobes can grow at that lower layer after the bacteria above them have consumed all that oxygen and provided them an oxygen-depleted environment to do their thing.”

Anaerobic conditions deep under biofilms can cause pitting of pipes, or microbially induced corrosion, a serious issue than can result in costly equipment failure. And without nonoxidizing microbicides, controlling that damage is even more challenging.

Following FSMA
Beyond the penetration benefits of nonoxidizing microbicides over oxidizing, the former also continues to serve its purpose after application. When the plant equipment is shut off, the oxidizing microbicides disappear within minutes, leaving no residuals behind, Lukanich explains. “Nonoxidizing microbicides will hang around for days or weeks,” he says.

“FSMA takes away a lot of our tools to treat systems and takes away a lot of the good things, or you could say bad things, to control outbreaks of microbiological activity,” Manstedt says. “So even if the system is relatively clean and clear today, on an FSMA program, that’s not saying you can be assured that it will remain that way down the road because if there’s a leak in a heat exchanger, you get mash, or if there’s a lapse in concentration of approved chemistries in there, it could start leading to damage in susceptible areas where it could get out of control. It’s important to be regularly monitoring the state of the cooling tower and to develop a treatment program to prevent biofilm outbreaks.” Ethanol producers need to be aware of their high-risk areas, stay on top of testing, chemical dosages and inspections, he adds. “Before, we weren’t too worried about a small increase in microbiological activity. Before, we could throw a little chemistry at it and it would take care of it. Now, we need to really be concerned about microbial activity, and a small trend in the wrong direction could have devastating effects down the road. You may not see it today. But a couple years from now, it could start to lead to problems.”

But not all ethanol plants must comply with FSMA. Some facilities do, across the entire site, even if the cooling water doesn’t come in contact with the product, Manstedt says. Others classify as noncontact cooling water and therefore may still use nonoxidizing microbicides. It’s up to each facility to determine what’s best for its operations, he says. “Right now, we’re kind of seeing a split a little bit, where the larger ethanol plants are going down the path of 100 percent FSMA coming into that facility, and some others are not. So it all depends on the facility, the risk they want to take and hazard analysis they want to complete.”

Lukanich says the best practice for biofilm control, in general, is to continuously feed an oxidizing microbicide, such as chlorine, into the system, with a nonoxidizing microbicide a few times per week. The two work together for optimal biofilm control and removal, he says.

But Manstedt points out that biofilm control does not have a one-size-fits-all solution. “It’s about knowing the facilities, knowing each specific plant, their tendencies and trends regarding biofilm and biological activity, and then applying the best strategies for that specific application.”

Mattsfield says prevention—through a thorough understanding of a plant and where the inputs are—is of course the best way to control biofilm, though it’s not easy. Effective and consistent clean in-place (CIP) strategies also are crucial. “I often tell people that the use of products like antimicrobials are usually important when you have infections, but proper CIP in a plant is probably the first step in trying to minimize biofilm problems.”

3-Pronged Approach
Solenis, a specialty chemicals provider, has a specific approach for biofilm removal and protection in ethanol plants. It’s dubbed ClearPoint and starts with an equipment-based phase that makes use of ultrasound to find biofilm. “We think it’s really a gamechanger and really revolutionizes the industry, in terms of how we can measure and quantify biofilm in real, industrial cooling systems,” says Michael Bluemle, senior team leader in the Solenis Water Applications Laboratory. It’s called OnGuard 3B and is designed to simulate a fermentation cooler, for instance, in terms of velocity flow and temperature. It continuously sends out an ultrasound signal to monitor the equipment. “If some biofilm does start to build up in the system, we can measure it very early on when there’s only microns-thick biofilm and we can react much more quickly with this online measurement, versus other, traditional offline measurements,” Bluemle says.

Once the biofilm is detected, the next step is chemistry. Solenis has a full portfolio of oxidizing and nonoxidizing biocides, as well as recently developed biodispersents to remove biofilm, according to Bluemle. The perfect cocktail is determined for each customer and then the third step begins: service. Bluemle says Solenis’ team of trained salespeople and experienced applications staff serves its customers’ specific needs.

Since FSMA, customers have expressed concern about and interest in the raw ingredients in Solenis’ chemicals, he says. “We’ve had to work closely with our customers to understand the regulations and limits, and then work internally within Solenis, within our regulatory group and applications and sales teams, from a technical standpoint, to make sure we’re meeting regularity requirements, but also still providing the kinds of high-performing treatment program that our customers expect. So we have to develop cooling water products that fit the biorefining industry because of the more stringent regulatory demands.”

For the Future
In light of changing regulations, Lukanich recommends ethanol plants consider alternative materials such as PVC and plastic piping instead of steel. “It’ll make their lives easier if they consider those.” Regulations also have removed a corrosion-inhibiting chemistry for copper, a metal that already is more susceptible to accelerated corrosion by chlorine than others. “Ethanol producers may have to be a little more accepting of slightly higher corrosion rates, which may still be perfectly acceptable.”

Bluemle says the strict regulations also are infringing on progress to develop new chemicals. “One trend in the industry is there doesn’t seem to be much innovation around chemistry. We are still working on developing new chemistries where possible, but it can be difficult in a market like biorefining, where regulations are more stringent and it takes more time and money to get things approved.”
 

Author: Lisa Gibson
Managing Editor, Ethanol Producer Magazine
701.738.4920
lgibson@bbiinternational.com