HUBER’s STRAINPRESS® Transforms Screening Process So Napa Sanitation District Can Maximize FOG System

Napa Sanitation District had been struggling with a bucket type strainer as the screening technology for their Fats, Oils, and Grease (FOG) receiving and injection system. After analyzing their struggles and other technology options compatible with the FOG system, the District chose to upgrade their screening technology to HUBER’s STRAINPRESS®. As noted by Operator III, Dusty Maynard, the technology change completely transformed their operational experience with results that helped them to maximize their FOG implementation.

FOG is a win-win.

Because FOG injection enhances digester performance, a Fats, Oils, and Grease (FOG) receiving and injection system is a desirable one to implement. The increased production of methane gas ultimately increases the amount of electrical energy the process can produce.

In the end, this internally produced methane gas generates electricity that offsets operations costs and creates new revenue in the sale of excess methane gas. According to Dusty Maynard, Operator III at Napa, “While the FOG system is a tremendous asset to us, it can create issues for us if the screening technology used with it doesn’t adequately perform. And that is what we were struggling with in using the manual bucket type debris strainers as the screening component of our FOG system.

From dinner forks to dishwasher gloves.

Napa saw all sorts of debris come into their bucket strainer. The problem was that all of it wasn’t getting screened out before it left the scene. “Basically, we must make sure that the flow into the digester is clear of debris,” said Maynard. “The more efficiently we can do that process, the better off we are in respect to cost and safety.

Non-digestible debris was showing up downstream of the strainer which isn’t acceptable if the FOG system is expected to work efficiently. The stream must be cleaned out ahead of reaching the digester because the potential it has for damaging it.

HUBER’s STRAINPRESS® stops all the debris. We don’t see debris beyond it so we can be confident that clean flow is entering the digester,” said Maynard of how clean the sludge has become.

Facing risky manual processes.

The bucket strainer clogged frequently causing a halt in the process that allowed operators to manually unplug it. This is nasty, hazardous work, and the odor is persistent and lasting and the waste stains and ruins clothing. It’s truly a foul experience. “I got a sharp stick in the hand from a sewing needle when clearing out the clogged bucket strainer,” said Maynard of their earlier screening bucket. “It’s a huge safety risk because of the environment you’re working in – with all sorts of waste, including heavy restaurant waste and waste from a chicken processing plant entering the stream. Each time we must clear out the bucket, we risk an injury and infection.

The HUBER STRAINPRESS® has processed a huge amount of waste without a single hitch. Because there are no clogs to manually clear, we never have to touch the waste and avoid any safety risks from doing so. And the bonus is that we also avoid mess and odor!

Plugged strainers cost man hours.

Stopping the process to unplug the strainer is time-consuming. “Anytime we must stop everything for a fix, it costs us. Even though the FOG system generates revenue in the end, it makes no sense to burn up the valuable time of our operators on clearing out clogs,” said Maynard of the expense and waste of dealing with clogs. Two to three times a day, operators must manually get the strainer back into working order. This adds up to approximately eight man hours per week. Those are eight man hours that operators could spend on more productive activities.

 “We’ve yet to experience a clog with the HUBER STRAINPRESS®! It has powered through more than 150 truckloads of waste and we’ve not spent even a half-hour unplugging it,” said Maynard of his STRAINPRESS®’ reliability.

The perfect choice for FOG system.

The HUBER STRAINPRESS® has helped Napa Sanitation District maximize its investment in the FOG receiving and injection system by improving operations, ensuring the protection of downstream components and enhancing the production of a valuable, revenue generating asset. “When we saw the Strainpress pilot at the nearby Walnut Creek Wastewater Treatment Facility, we knew that we wanted to implement it. Instead of Huber taking the pilot component back to its headquarters, we simply had them bring to our site. Since day one, the Huber Strainpress has done a wonderful job,” said Maynard of his feeling about HUBER from the start. The HUBER STRAINPRESS® integrates well into the FOG system to be an integral part of its success.