How universities in opposite climates are dealing with onsite water treatment
By Peter Hildebrandt
As years go by, colleges become a better and better fit for treating and improving recycled water, researching different onsite water treatment (OWT) issues, and training the growing ranks of OWT professionals.Many colleges have the scientists and professionalsalready in place and, if they are so inclined, can use the university’s OWT as a teaching tool. Some, like University of Florida–Gainesville (UF), are extremely diversified in their recycling of wastewater. Other colleges or universities contain centers for research, such as two cold-climate centers in Alaska and Canada that are dealing with unique challenges that come with subzero temperatures.
Water Reuse—For Golf Course, Gator Field, and Even Cogeneration
The University of Florida–Gainesville has a wastewater treatment plant that also contains a research lab for students at the school. This facility is used for students from the US as well as many from various countries worldwide. The flow of the five-phase system can be completely controlled by computer, as well as the return sludge or nitrates and ammonia. The facility is regulated as any other wastewater treatment center in the state of Florida. (For an in-depth description of these phases see www.ufwrf.com/nit_phos.html.)
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Photo: Utah Water Research Laboratory |
UF has been successfully operating its wastewater treatment plant at the campus reclamation facility for some 14 years. UF’s Gator Field, golf course, softball fields, and law library and a number of other locations use the water on their grounds. At times, up to 3 million gallons per day will enter the treatment plant, and on football game weekends this amount can easily shoot up to 6 million or 7 million gallons daily. On the other hand, on holiday break week or some weekends that amount may drop to fewer than 1,000 gallons per day. The recycled water is used basically all over campus.
Sludge is kept in a holding tank before being sent to the Gainesville Regional Utilities (GRU). The tank is not an anaerobic tank, so the sludge is treated with a polymer before being hauled to GRU. The tank company finishes it by adding lime to raise the pH before shipping it to a fertilizer landfill.
There are a lot of sectors at the campus that use the recycled water. When the water-reuse tank level drops to 10 feet, the irrigation lines feeding out to the campus are shut down, in order to meet the needs of a Florida Power cogeneration plant located on campus. “At times of low flow we have to shut off our water to the irrigation uses as well as to the cogen plant because we don’t have the water to give them,” says James Williams, senior plant operator.
“Currently we’re designed to treat 5 million to 6 million gallons per day, but at times we treat over 7 million gallons per day. Since our water is basically all recycled, we have very little waste here on campus. If we do have a problem, say with one of our pumps going down, I find that our effluent storage tank is one of the best things that can be designed.
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Photo: Cold Climate Housing Research Center |
| Universities in the diverse climates of Alaska and Florida have one common goal: research and application techniques of water reuse. |
“We also have an outer ring tank, which we call our ‘reject tank,’ where we send sludge until things clear up. We’ve had to do that a few times. If we don’t have enough water to support the community, we’ll tell them that as soon as the water clears up, we’ll send it to them.”
The three-ring tank system features a center tank into which contact water is sent. But if the sodium hypochlorite is too high at this point, this tank gives it a chance to dissipate by sending the water into the second tank. Water from the second tank is sent out to the users, and the last tank is used only if there is a problem with the water, such as the turbidity or the chlorine being too high or too low. The tanks used at UF are manufactured by Kruger, a Danish company (www.krugerusa.com).
Florida has been in the midst of a prolonged drought, so the use of recycled wastewater on campus is especially helpful, especially at night, because when watering in the day, the sun will evaporate a substantial portion of the water. “Over time I’ve noticed a clear difference as soon as the switch is made from day to night irrigation,” says Williams.
For the UF golf courses, water is piped through an underground 8-inch line directly from the treatment plant to a 2-acre pond on the golf course. At the pond a valve is set with a solenoid switch and a timer.
“Because the rest of the campus is also serviced, we have a time between 2:00 and 3:00 [p.m.] when our solenoid lets the valve open up to fill up our pond each day,” says Todd Wilkinson, UF golf course superintendent. “We then run our irrigation system at night with water from the pond.”
The only problem so far was from a sinkhole that developed a year or so ago, causing a loss of water. But after fixing that, everything has continued to work out well. “Every once in a while when the students are gone and less water is flowing into the system, we will see a drop. But at those times we have our own backup system with deep wells we can switch on to fill up our pond if we’re in any trouble. Normally, with rainfall and water from the physical plant, we do OK,” says Wilkinson.
Another use for the recycled wastewater is creating steam for the UFcampusand Shands Teaching Hospital complex. The reclaimed water is turned into demineralized water by use of multimedia filters, chlorination, and the addition of acid to lower its pH, as well as running it through reverse osmosis (RO) units. From the RO storage tank it is run through mixed-bed demineralizers before it is turned into steam.
“We get a certain amount of the water or condensate returned in this process,” says Reed Franklin, UF cogeneration plant operator. “But there are some losses through the course of this steam traveling through some 40 miles of steam pipes campuswide. These pipes travel to buildings, hospitals, and research centers scattered throughout the UF campus; therefore, we don’t get 100% back.”
The collected condensate runs through polishers to remove minerals and impurities, such as silica or sodium, as well as anything else present in the water. This water is then placed in a holding tank with the rest of the demineralized water.
The reject material from the RO units is placed in a waste pit filled with high-conductivity water full of minerals and other materials. Finally, it’s returned to the physical plant, where it’s mixed in with all the other wastewater and recycled.
“We use a GE LM6000 jet engine to generate electricity,” adds Franklin. “The heat created from the jet engine exhaust is ducted to a heat-recovery steam generator to convert the demineralized water into steam. It’s an interesting process and a great way to benefit from the recycled wastewater on campus without having to use potable water for the creation of steam.”
Unique Climate and Geologic Setting for College
The Cold Climate Housing Research Center (CCHRC) on the University of Alaska–Fairbanks (UAF) campus is working with major infrastructure issues including water and wastewater. It is working with the chairman of the Institute of Northern Engineering. This is targeted as a Leadership in Energy and Environmental Design Gold building, but the CCHRC incorporated a lot of innovation into its systems.
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Photo: Cold Climate Housing Research Center |
| The Cold Climate Housing Research Center works closely with the Alaska Department of Environmental Conservation. |
This research park–type facility opened in September 2006. After extensive fieldwork, part of the plan was to build the facility as a home for the CCHRC’s statewide research agenda. Though the center is on the UAF campus and has something of a symbiotic relationship with the two organizations, each helping the other with research and resources, it does remain a standalone entity as well.
“We have manyindustry partners as well as being a private, not-for-profit entity,” says Jack Hébert, president and chief executive officer of the CCHRC on the UAF campus. “But public agencies, in particular the Alaska State Housing Finance Corporation, are major partners and financial supporters of our mission, as well.”
The building captures rainwater as its graywater stream. That is used for flush and irrigation. All the flush and washwater goes into an onsiteextreme sewage treatment plant, specially designed for this area of the country. The plant is small, located in the building, and sized for a total of 50 people. It treats the water after it’s processed to surface-water discharge standards.
The system has no inspection requirements that are unique to this system, according to John Davies, CCHRC research director. “The system has been generally preapproved by the Alaska Department of Environmental Conservation [DEC] for surface discharge,” says Davies.
“The only difference in the way we installed it and the way it’s normally installed is that we installed it in our basement to have it research accessible. In general, it would be insulated and installed outside. When the system is properly insulated and on a surface location, the heat from the fluids entering the system and from the air pump using 300 watts of electricity is enough to keep it operational at the 60-degrees-below-zero temperatures which can occur in the area.”
The system is manufactured in Fairbanks by Lifewater Engineering Co. (www.lifewaterengineering.com).
The CCHRC plans to put the water back into the graywater stream rather than discharging it. In effect, there will be no effluent leaving the building at all, other than irrigation water. When the temperatures drop to 50 degrees below zero the water can still be discharged; it just creates a little glacier, as Hébert explains.
“There are a lot of these systems in Alaska,” says Hébert. “The difference, though, is that here we are bringing discharge water back into the graywater cycle. Our goal is to treat the water to meet potable water standards.”
UAF uses a package plant made by USFilter (which was recently purchased by Siemens Water Technologies) inside a building for treating drinking water. The system consists of two filtration trains, including two flocculation basins, one sedimentation basin, and one filter. These two systems rest side by side. The water flow is split between the two filter trains. The beginning of the process is the water coming into the aeration tank. Water fills the aeration tank as air bubbles up from the bottom. It’s then pumped from the aeration tank over to the two filtration trains.
The drinking-water treatment plant in another area of UAF’s campus has the distinction of using an extensive aeration process. This is vital to the treatment scheme. Several years ago a contamination incident occurred in the well field involving a gasoline spill in the aquifer that the campus pulls from. The aeration system showed potential benzene contamination.
Some 30 air turbines operate on the bottom of the tank, a Ramco product. These include a multiblade turbine introducing air on the bed where it rises up. The bubbles formed are then chopped down from coarse to medium in size. The fans also help volatilize the benzene in the first treatment of the process. Likewise, this helps begin the oxidation process for iron and manganese.
This area of Alaska has much iron (15 to 17 milligrams per liter in water samples) as well as manganese in the environment. Private wells have elevated iron levels, depending on location. The main river running through the Fairbanks area is the Tanana River, with the Chena River being a tributary. Depending on how close wells are to the river, iron levels will vary.
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Photo: Cold Climate Housing Research Center |
| Canada has embraced cold-climate water-reuse studies at its universities as well, as demonstrated at Fleming College. |
Groundwater levels for these minerals fluctuate with the river seasonally. The area also has elevated levels of arsenic due to aresenopyrite formations around Fairbanks that figure in the city’s history as a gold mining camp. Arsenic is associated with gold ore deposits.
“We are actually able to remove arsenic from our water,” says Ben Stacy, water plant supervisor at UAF. “We’re not sure if it’s a binding or an oxidation process. More likely than not it’s an oxidation process, as we’ve found that if we feed a fairly high level of potassium permanganate, then we can get rid of the arsenic. With somewhere around 9 to 10 milligrams per liter feed rate of potassium permanganate, we’ve found we can drop out the arsenic.”
The last raw water sample that Stacy took was approximately 40 parts per billion (ppb). The program is able to take that down to non-detectable levels, effectively going from 40 ppb to zero on the arsenic level.
“One of the unique things about our plant—and I’ve had other utilities call about their aeration and foam—is that we have a whole separate tank containing the aeration process so that we don’t get that foam spilling over into our flocculation tanks,” adds Stacy.
The system is rated at 1 million gallons per day. A lift station in the university’s power plant removes all the wastewater for the power plant and water plant, which is then treated by the local wastewater utility.
UAF also has an extensive bank of granular activated carbon (GAC) filters. The 10 filters are run five at a time. Each one of the units takes approximately 1,900 pounds of carbon. They feed all the water through all five of them at a time; it is simply divided between the five different tanks.
This helps remove any benzene that may be left over in the process to be absorbed through the GAC filtration. Likewise, this helps with some of the organics removal that the university must be concerned with when it comes to trihalomethane (THM) formation in the distribution system.
“Other than the aeration and the GAC filtration, we are a conventional filtration plant, going through the typical coagulation, flocculation, sedimentation, and filtration involved in standard plants,” says Stacy. “We simply have two other processes involved.”
UAF is trying to organize a pilot study for installation of a nanofiltration unit. “Once some of the terms and conditions are worked out on such an installation, we are leaning in that direction,” says Stacy. “Obviously membranes are the way of the future. We want to go ahead and take a look at what membranes can do for us. Our raw water coming into the plant is extremely high in organic carbon, upward of 12 to 14 milligrams per liter. That’s really pretty unique for a groundwater system. Typically you think of groundwater as being lower in total organic carbons [TOC].”
The university hosted a training event in February 2007 for its local division of water through the Alaska DEC. “The trainer who came in and worked at the event and who works across the country giving such events admitted he’d never seen a groundwater system containing such levels of TOC entering it,” says Stacy. “We are able to bring that level down from 12 to 7.5. Most of the time we’re running at around 9 for finished water TOC.”
Stacy works closely with the Alaska DEC. The DEC is only two blocks from his facility. “I have worked with them recently on the upcoming Stage II Disinfection Byproduct Rule,” adds Stacy. “Our system must get the first report in by April 2008. But this will be submitted to the EPA, not to the Alaska DEC. We have been working with the DEC on laboratory test methods produced by the Hach Company.
“The DEC has actually been coming over and using my lab equipment with their own reagents to run this THM+ Method, which Hach Company has come out with to study disinfection byproducts and optimize plant performance. Their objective is to become more familiar with the method when they travel to rural locations around the state—such as communities in the bush—with their own water treatment plants. The push is to correlate data between our contract laboratory and the THM+ Method. It’s a means to keep an eye on conditions in our system without having to send off a set of samples and then have to wait two to three weeks for results.”
College Centre for Alternative Wastewater Treatment
Fleming College in Lindsay, ON, has the Centre for Alternative Wastewater Treatment. The center is grant-funded by the Canada Foundation for Innovation and the Ontario Innovation Trust. The initial grant of C$1.6 million was for providing funds to build the infrastructure, with a mandate for specialization in alternative approaches to wastewater treatment in cold climates. Fleming College is mandated by the provincial government to do research.
The facility is state of the art and is part of a new 40,000-square-foot environmental wing at the college. Included at the facility is a 2,900-square-foot greenhouse for indoor experiments. The center’s outdoor concrete cells house a simulated wetland treatment system that treats all the wastewater from the new environmental wing in addition to any other waste the center chooses to treat there. The center opened in 2004.
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Photo: Cold Climate Housing Research Center |
| Research’s added bonus: wastewater
treatment for college campuses. |
“Because this system is designed for research purposes, there is a SCADA [supervisory control and data acquisition] system, which monitors the whole bank of portals in order for us to receive real-time monitoring of a number of parameters, flows, temperatures, and a number of other variables,” says Brent Wootton, senior scientist at Fleming College. “Researchers can then use this information through computerized systems to recirculate or send effluent in one direction or another or control it. Those six particular cells are a great research tool as are our 20 [measuring 20 feet by 15 feet by 5 feet] ponds that are lined and linked with plumbing to send or remove effluent. Our instrumentation enables the center to study any parameters, including organics, metals, and many others.
“Our system is over-designed for research purposes,” says Wootton. “This is so that we can examine specific processes in detail. It consists of two parallel sets of three cells—horizontal, vertical, horizontal. The cells have monitoring ports throughout and a SCADA to control and monitor flow, temperature, and whatever other sensors we put in.
“It’s designed primarily for research but also happens to treat the school’s wastewater. It is not subject to regulations because we discharge directly into sanitary sewer. This allows us to pursue a research mandate for the system versus performance, although it’s extremely effective at treating the school’s waste—even in winter.
“We have a mandate to do knowledge creation, original research, and technology transfer, just like major universities would do,” adds Wootton. “The center also supports applied learning by enhancing curriculum and having students involved in their own research projects. The decision to become a world-class research facility where research is done for its own sake benefits not only researchers, but the students also benefit from being able to see peer-review-level research in action.”
Fleming College also does community development projects to benefit those in the developing world. According to Wootton, most of the research happens offsite. The college recently received major funding from the Canadian government for the International Polar Year, which started in March 2007. The $700,000 it received will assist in doing wastewater treatment research in remote Inuit communities in the Arctic.
Peter Hildebrandt writes extensively on engineering and scientific subjects.
OW - January/February 2008
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