The Rose Hill (Kan.) Resource Management Facility does much more than reclaim the city’s wastewater and return it to the environment. It incorporates a single-stream recycling center, a tree farm and a green-waste composting facility.

Add that to cleaning the water and producing Class A, EQ biosolids and you’ve got a facility that practices recycling in its broadest sense.

Despite the bright recycling picture, its operators face a problem many clean-water operators struggling to run plants that are past due for modernization and expansion would love to have: an underloaded plant. Its design capacity is four times the average hydraulic load.

Jamie Belden, Dillan Curtis and Adam Pompa face that challenge with enthusiasm. Their plant can treat 1.1 mgd, but actually processes only 250,000 gpd. In the words of Curtis, lead water and wastewater operator, “It’s not an easy O&M problem.”

Jamie Belden, Public Works superintendent, says the operations staff members scratched their heads and worked together to come up with solutions. Belden had run an underloaded plant in Wichita, but, “When you’re operating like this, a lot of your textbook stuff flies out the window.

“We’ve learned to rely on our oxygen levels between basins and to operate with the philosophy that if we hit the right oxygen levels in the anaerobic and anoxic zones and the oxidation ditch, and operate with higher activated sludge return rates, we’ll be successful.”

Apparently so: The plant, completed in 2009, won the 2012 Kansas Water Environment Association (KWEA) Plant of the Year Award in Class 3 (plants serving 3,500 to 10,000 population).

Internal loops

The Rose Hill facility serves a population of 4,000 in a bedroom suburb about 11 miles from Wichita. It sits mostly alone about a mile outside town. A subdivision has grown up to the north, but other neighborhoods have not encroached.

Four lift stations in town and a fifth at an industrial park feed the plant via a force main. Flow comes into the headworks where a spiral screen (WesTech Engineering) removes trash and debris. After passing through grit removal (Kusters Water A Div. of Kusters Zima Corp.), the water goes to an anaerobic zone for denitrification, then to an anoxic zone and the oxidation ditch.

Some overflows to the clarifier to settle the settleable solids. Clear water then goes over the weir to a UV disinfection system (Evoqua Water Technologies) and cascades to re-aerate as it enters Eightmile Creek. Return flow from the clarifier goes back to the anaerobic zone. “The internal loops are the only way to make it work,” says Belden. “We do that to remove nitrogen and the phosphorous.”

Belden said the staff has increased the return activated sludge rate to achieve detention times closer to the design times. The basins are sized for detention times associated with a flow of 1.1 million gallons per day, yet detention times are longer because the actual flow is only 250,000 gallons per day.

Sludge wasted from the process goes to two anaerobic digesters. A belt filter press (Aero-Mod) dewaters the digested material to 18 to 20 percent solids. Biosolids are dried in windrows outside. Hot, dry summers like those of the past two years have yielded an E. coli count of zero and an 87 percent solids Class A Exceptional Quality biosolids product, used at the plant to help grow trees and elsewhere in the city in gardens. Belden is working to develop a long-term, free-distribution plan for the community.

Consistent compliance

The plant began operating in 2009. Before then, the city had a smaller lagoon system but had trouble meeting discharge limits even after expansion. “We were ‘strongly encouraged’ by the Kansas Department of Health and Environment to build the present facility,” Belden says. The lagoons remain available for extraneous flows, meaning extreme wet-weather events, or times when equipment failures take the processes offline. The flow could be returned for reprocessing if necessary, but most of the time the water is simply allowed to evaporate.

The plant was designed for easy expansion with population growth. “It’s stubbed out so we can add mirror-image processes,” Belden says. Professional Engineering Consultants designed the plant, and Walters Morgan Construction built it. The plant’s discharge limits “are pretty strict, but we’ve never even come close to exceeding any of them,” says Belden.

The ammonia limit swings from a high of 6.4 mg/L in winter to a low average of 2.2 mg/L from June to August. As of now, there are guidelines but no firm limits for nitrogen and phosphorus. “We monitor them,” Belden says. “The Department of Health and Environment wants to see 8 mg/L for nitrogen and 1.5 mg/L for phosphorus. We typically achieve our annual averages pretty easily.” Nitrogen averages less than 5 mg/L and phosphorous 1 mg/L.

Sustainable performance

Belden believes the KWEA Plant of the Year award recognized the plant’s good operations and maintenance, its energy-efficient design, and how it lives up to the “resource management” part of its name. One energy-saving feature Belden appreciates is radiant heating in the floor of the precast concrete administration building. “We recently had one of our coldest winters in a long time,” he says. “Because the heat is in the floor, we rarely had our furnace kick on.”

The “furnace” is actually a small electric boiler — it uses much less energy than a furnace. Hot water circulates through the floor, heating it and allowing the heat to rise. This arrangement helps maintain a comfortable temperature in the work areas without heating the overhead space.

The administration building lighting is all compact fluorescent, and the facility is moving toward LED lighting at lift stations. Occupancy sensors keep spaces from being lit unnecessarily.

All pumps at the plant have variable-frequency drives with soft starts. “That saves energy and helps make the equipment last longer,” Belden says. “The engineers designed the plant to be as energy efficient as possible. In the long run, they saved the city and taxpayers money.”

Recycling plus

Kirk Hayden, Public Works director, pushed for the entire resource management idea, including radiant heating and the electrical energy-saving features, during plant design. “I wish I’d thought of these ideas, but I inherited them,” Belden said.

The plant is also attractive in appearance: “People usually don’t want to live next door to a wastewater treatment plant, but we’ve addressed that.” The tree farm, recycling and green-waste processing use normally empty space next to the treatment plant. “This encourages citizens to become acquainted with the facility and ask questions, thus minimizing the wastewater stigma,” says Belden. “And odors are minimal unless there’s a process issue.”

Single-stream recycling is a joint city-county venture. Residents bring in recyclables but don’t have to separate them. A recycling contractor separates and removes them.

The plant takes green waste such as tree branches, limbs, trunks, and stumps and chips them to make mulch. The city’s Streets and Parks Division, which Belden also manages, runs that process. Mulch is used at the plant’s tree farm and is provided free to citizens. The plant also takes in grass clippings and makes compost for citizens’ use.

At the tree farm, Belden’s goal is to grow enough trees to satisfy the city parks’ needs, and to offer any surplus trees at a discount to residents. He gets excited when describing how the resource management facility is helping to educate the public.

“Most people think the tree farm is pretty neat,” he says. “They drive by and see that we’re growing trees, and it stimulates questions. When we explain it, they say, ‘That’s a great idea.’”

Emphasizing the recycling also helps when school kids, Boy Scouts, Girl Scouts and others come for plant tours.

Belden starts tours with a simple question, like “What can we recycle?” The usual answers quickly go toward the single-stream center and green waste, which the visitors can easily see. Belden then leads them to think about recycling water: “I talk about water and that there’s no new water being made, so we have to recycle what we have. Then we talk about how we do our part in cleaning the water here, and we talk about where it goes.”

He finds that the adult chaperones often get more interested than the kids. “I’m trying to promote community involvement,” he says. “It’s a huge part of getting the word out and helping our industry. It also helps get more people like those with biology, chemistry and engineering degrees interested in running these modern, complex plants.

More Information

Aero-Mod, Inc. - 785/537-4995 - www.aeromod.com

Evoqua Water Technologies, LLC -  866/926-8420 - www.evoqua.com

Waste Tech, Inc. - 847/986-2735 - www.wastetechinc.com

WesTech Engineering, Inc. - 801/265-1000 - www.westech-inc.com