Yuba City, California, like most cities across the nation, has experienced growth. Parts of its sanitary collections system are now being asked to perform at top capacity and handle more than their fair share of conveyance on a daily basis.

In one such structure, this was creating the ongoing challenge of fighting odor issues without a long-term resolution and with a never-ending maintenance expense. Accepting an offer of a pilot test unit for a new technology designed for wastewater treatment plants is showing itself to be the answer Yuba City has been waiting to incorporate for decades.

Long history

Serving a population of approximately 72,000 with a system comprised of 200 miles of sewer main, 2,400 manholes and 17 operational lift stations, Yuba City’s small and efficient collections team has a full plate of work. Tim Bybee, wastewater collection supervisor, and Diana Langley, Public Works director, wanted to see one task eliminated: the weekly cleaning and constant maintenance of Lift Station No. 2.

Built in the early 1950s, the lift station was originally designed to act as the city’s wastewater treatment plant. Then in 1979 when the city’s new treatment plant came online, the structure was converted into a lift station. In 1992 it was upgraded with three 30 hp submersible pumps, each capable of pumping 800 gpm. Despite the upgrade, the system is pushed to the limit, responsible for moving an average of 2-3 mgd.

Odor issues became prevalent in the lift station over time, so in 1991 a charcoal filtration unit (Purafil - a Filtration Group Co.) was installed. The charcoal system worked for a while, but as the city grew and more flow came through, the unit was not able to keep up with demand and odor became a routine issue.

The right answer

The maintenance team began a preventive maintenance program of replacing the charcoal in the unit annually, but this became challenging as the material was difficult to procure and became increasingly more expensive. Chemical odor control methods were then considered, but these also were costly and carried safety liability for storage and handling.

“Director Langley challenged us to search out a long-term solution and consider other technology,” Bybee says. “She opened my eyes and view of our current system — that a solution you start with may simply become obsolete for your situation. It doesn’t mean that it isn’t a good solution; it just isn’t the right answer to meet the current needs.” 

While they hunted for new options to combat the odor, crews were dispatched to clean the lift station with a jet/vac truck on a weekly basis. The crews extracted on average 1,000 gallons of FOG per week. They also adjusted pump controls, lowering the pump on offset points to reduce detention time. This resulted in minimal odor improvement and created the potential of ragging up the pumps. In the long run, adjusting the pump controls as a solution was not successful and was abandoned. Even with this valiant effort, and an annual cost of nearly $70,000, the odor persisted.

Pilot test

Bybee had been in conversation with Lewis Titus of Titus Industrial Group about various wastewater technologies they offer when the subject of odor control systems came up. Upon hearing about Yuba City’s issue, Titus was confident he had a solution with their TITUS Twister Mixing Aerator.

“I was skeptical,” Bybee says. “I deal with a lot of different vendors, and sometimes it feels like it’s just another sales pitch. But Lewis was adamant that we had to try it and so confident it would work that he offered to bring us a pilot unit to try at no cost. My director felt we had nothing to lose so we agreed.”

Titus delivered a trailer-mounted TITUS Twister and set it up next to the lift station. The patented system consists of a Twister head, regenerative blower and enclosure. The Twister heads are comprised of stainless steel manifolds, stainless steel ballast plates, PVC barrels, HDPE shear blades, HDPE horizontal flow deflector plates and stainless steel coupling connections. The head is connected to the blower by either EPDM hose or stainless steel hard piping. For the Yuba City application, two Twister heads were installed into the wet well, driven by two 3 hp regenerative blowers, and enhanced with ozone generation.

Air is generated by the regenerative blower inside the trailer enclosure. The air is then delivered to the aeration units and through the manifold in the lift station through two EPDM hoses. In the Yuba City unit, a 40-gram-per-hour corona discharge ozone generator was used to produce ozone from the ambient air. This was incorporated to enhance the unit’s odor control properties. Openings in the manifold create air bubbles that transfer oxygen and ozone into the effluent.

Within the unit’s barrel, an air lift column is created. That forces liquid and solid materials up into the static shear blades and flow deflector plate. Solids are broken up and directed back into the cycle. Liquid and solid materials are continuously drawn in through ports located at the bottom of the barrel, creating a constant suspension of materials within the lift station.

“Within the first hour, even running at half capacity, everyone who was present concluded that this was the technology we needed: The odor was gone. Pumpouts for the FOG matter have been reduced 95%, and ragged up pumps have been eliminated,” Bybee says.

Permanent solution

Bybee presented the results to Langley, and they were taken to city council and approved for purchase. The city is now installing a TITUS Twister Mixing Aerator into a permanent structure adjacent to the lift station.

The Twister’s aboveground components will be housed where the original odor control system was, alongside other control equipment for the lift station. The building is being rehabilitated for this purpose, and instead of the EPDM hoses used during the demonstration and trial, (in conjunction with the trailer-mounted version) stainless steel piping will be run underground into the side of the lift station and onto the heads directly in front of the aeration pumps. 

Once the building renovation is complete and the permanent equipment is installed, the city investment will be approximately $85,000.

“We actually predicted that between the maintenance equipment operation costs, the charcoal unit upkeep and labor we were putting in, this new unit will almost pay for itself in one year,” Bybee says. “I wish we had tried it sooner, and we’re glad that Titus had so much confidence in their system and gave us the opportunity to take it for the test drive.”