Not long ago, a Utah food manufacturer turned to SCS with a persistent problem: high concentrations of fats, oils, and grease (FOG) in its wastewater— high enough to clog the city’s sewer line, knock it out of compliance, and cost it a steep surcharge year after year. As the plant worked toward a solution, its customers’ demand was growing; it reached a point where it had to expand to keep up, and that’s when the quandary came to a head. The meat processor couldn’t get a permit for expansion until the FOG was in check.
Within 18 months, SCS Project Director Mark Pearson and his team of liquid management gurus had their client within acceptable discharge limits for the first time in years. Actually, the plant’s doing a lot better than meeting the city’s requirements. Its FOG concentrations, which had spiked to thousands of mg/L, are consistently down below the established discharge limit of 200 mg/L.
The scenario Pearson walked into is that the wastewater generation and pollutant loading were highly variable as flows fluctuated. Due to hydraulic limitations, the treatment system couldn’t keep up with volumes during peak flows. As a result, the influent (untreated wastewater) was discharged from the plant to the sewer to the municipal wastewater treatment plant. And because the system was overtaxed, it did not sufficiently break down the FOG, which exacerbated the problem, wreaking havoc with the city’s collection pipes.
After completing the initial assessment, Pearson’s team developed a multifaceted approach to debottleneck the system’s hydraulics and make other improvements to increase FOG removal efficiency.
Pearson; Dean Free, senior project manager; and Nathan Hamm, program lead for wastewater and liquids management, came up with a design that achieves two main goals: It eliminates uncontrolled discharge from the plant; it greatly reduces concentrations of FOG—cutting the contaminant load to the city. Not only is the client within discharge limits, but it’s also pushed through its most immediate barrier to expansion permit approval. And it’s improved its relationship with the city.
The solution is a complex one involving chemistry, mechanical engineering, and electrical engineering. But to pare a lot of fine details down to the nitty-gritty, Pearson says:
“We put in screens that remove solids in the wastewater. We constructed a 60,000-gallon tank to equalize the flow coming to the plant. We adjusted pH to help optimize the wastewater treatment chemicals’ effectiveness. We separated the influent tank from the effluent (treated water) pipes to solve a problem where the influent would overflow into the effluent through a perforated wall. The new piping setup makes overflow impossible. And to further fortify the system, we installed a lift station to capture previously untreated wastewater.”
As a bonus, the team installed a tank that the separated FOG residual is pumped to, then hauled to a compost facility for beneficial use.
Besides adding these system enhancements, the SCS team took capabilities further with a process control and instrumentation component. The technology monitors flow rates, temperatures, tank levels, and other conditions. It processes the data and automatically makes adjustments to achieve treatment goals, avoid production downtime, and enable operators to respond proactively should they see a red flag.
Comparing the old to the new way of monitoring and analyzing, Pearson says, “What our client had before was rudimentary information. And while they could monitor conditions, they had to walk around the plant. All of the operational data can be viewed on a screen now from one location. They have more data at their fingertips and more capability to make adjustments to avoid discharge exceedances.”
The wastewater treatment system upgrade was done as a design-build to speed the timeframe while also increasing efficiency. “We could immediately start rather than put it out to bid. We could do construction as we designed. And there was one entity and one point of responsibility. So what’s cool is we leverage both SCS engineering and construction capabilities to solve problems,” Hamm says.
He and his colleagues have the know-how to pivot on a dime if they have to, and there were a couple of times it was necessary, including when the client brought new management on board midway through the installation process. The new team preferred different instrumentation and had a specific scheme in mind.
“We were in the process of installing the original instruments. But we were able to incorporate their equipment preference midstream. We had to figure out how to get new instruments installed and ensure they were perfectly integrated with the computer control system that takes readings from the instruments. It was what they wanted, so we saw that they got it,” Pearson says.
While he and his co-workers’ jobs as project design and build engineers are done, they have not faded from the picture. They provide ongoing technical support when the client needs assistance with troubleshooting. The automated control system has helped.
“This is a robust and complex mechanical treatment system. If by chance, something was wrong, our client can transmit data that comes out of the process controller so we can work remotely to determine if process changes are needed. If they are, we can often make those changes from offsite, and quickly,” Hamm says.
But the SCS team also plans so that its client is equipped to ensure its success moving forward. They provide operator training. And they developed a standard operating and maintenance procedures manual and a checklist to track data and activities transferred from shift to shift, providing operators a standard and seamless way to communicate.
The busy Utah plant is on a good trajectory, with solid footing.
Says Pearson: “Before, they could not expand the plant or even continue their operations much longer if they did not get the FOG under control. Now they can operate continuously, discharge to the city, and they have potential to expand their plant because they are showing the regulators they can stay within their permit limits.”
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