New Pump Technology

New Pump Technology
May Improve Small Package Plant Treatment

NSFC Staff Writer
Natalie Eddy

Editor’s Note: A major part of the National Small Flows Clearinghouse’s mission is to report on new technologies as we become aware of them. It is in that spirit that we present this article. Mention of a product or service in a Small Flows Quarterly article is not an endorsement by the NSFC. All manufacturers and consultants who have not registered themselves in the NSFC’s database are invited to do so by calling our technical services department.

Small flow wastewater treatment package plants (plants treating fewer than one million gallons per day) have a history of poor settling in the final clarifier, but a new wastewater treatment package plant pump, called the Geyser Pump, may be the long-awaited answer for operators.
“Being an operator for a wastewater treatment package plant can be a nightmare,” said Warren Peace, who has installed Geyser Pumps in seven plants in West Virginia, Virginia, Kentucky, Tennessee, and Maryland. According to Peace, all of the system operators have experienced improvements. “These small package plants are 10 times more difficult to operate than full-size systems because of the difficulty in
maintaining a solids inventory.
“The discovery of this pump was very liberating. I wanted to get the word out to these plant operators that there is a solution. Finally, a pump that can handle a 2-inch solid, has no moving parts, and has the capability to accurately deliver very low rates of flow, typically less than 2 gallons per minute.”
Peace, an environmental engineer who owns Advanced Engineering Services of Botetourt County, Virginia, said the device gives wastewater treatment plant operators with plants processing fewer than 40,000 gallons per day (gpd) the same measure of control as operators of plants processing 10 million gpd.
Masao Kondo, who holds a doctorate in mechanical engineering and owns NCA2 of Dunn, North Carolina, developed the pump. Peace contacted Kondo after learning about the pump from a friend who had attended a presentation about it at a conference in North Carolina.
The two worked out an agreement to distribute the pump, and Kondo received a patent for the device in December 2000.
The Theory
“The difficulty in controlling solids in the clarifier is due primarily to the method of sludge return,” said Peace. “If the population of biological solids (mixed liquor suspended solids—MLSS) gets very high, greater than 3,500 milligrams per liter, or if the plant experiences an upset, solids will exit the clarifier.”
“In many small systems, the rate of flow reduces residence time in the final clarifier to less than one hour.”
He explained that in a typical airlift pump, air rises and pushes the effluent along when the air’s buoyancy is greater than the weight of the liquid. However, the trouble arises because there is no way to control the amount of air delivered.
“Airlift pumps are nice, but they are either on or off,” said Peace. “If you try to slow them down, they just stop. With the Geyser Pump, the air bubble is made in a separate chamber. You can control the formation of that bubble by how fast you put air into the line.
“If you want to pump 2 gallons per minute and have a gallon of fluid in the riser of a 2-inch line, you would want the pump to pulse twice a minute. You would have to fill the chamber at a rate that produces a bubble twice a minute and then you would have 2 gallons per minute. It’s that simple.”
Peace said with the Geyser Pump, return rates can be reduced to 100 percent of influent flow or lower, if necessary.
The old airlift method is very reliable, according to Peace, provided the operator maintains an adequate supply of air to the system. Conversely, if the air supply is not adequate, the pump will stop operating.
Pump It Up
The idea that the Geyser Pump is based on is not a new concept. In fact, the idea of using air to move liquid originated in the 1780s, according to Peace.
For years, an airlift pump consisted of a vertical tube with 60 percent of its length submerged, and an air supply line entering the vertical tube greater than four pipe diameters from its end. If the air flow is sufficient, the buoyant force of the bubble will grow greater than the weight of the column of liquid above it pushing the liquid out of the end of the tube.
“The greatest advantages of airlift pumps are their lack of moving parts and their ability to move large or heavy solids,” said Peace. “One of the greatest disadvantages to using an airlift pump is its limited useful range of flow. If airflow to a typical airlift pump is reduced by a relatively small amount, it will cease to operate.
“The Geyser Pump significantly improves the characteristic advantages of the airlift pump, while allowing it to operate over a much larger range of flow rates.”
Peace explained further that the bubble is produced in a chamber outside of the pump riser. Air is supplied to an airtight dome that has the pump riser extending through the center. Inside the dome is a second, smaller, inverted air dome with the pump riser also extending through its center.
“Imagine the old diving bell that looked like a bucket on the divers’ heads,” said Peace. “We’ve taken a dome or diving bell and placed a pump riser through it with an additional cylinder that puts air inside until the air pressure rises.”
An entrance is provided to the riser pipe, capable of allowing a bubble greater than the diameter of the pipe to enter. As air is applied to the larger dome, the pressure inside increases until it is greater than the pressure of the column of water in the pump riser.
“When this condition is met, a bubble is released from the air dome into the pump riser. Then, just as in a typical airlift pump, the bubble rises and carries the column of liquid in the riser out the end of the pipe,” Peace added.
“This sounds very simple, but it is revolutionary in two ways. First, it requires the use of significantly less air to operate relatively large airlift pumps. Second, it allows an airlift pump to provide a very predictable and controllable rate of flow.”
Getting Pumped
Installing the Geyser Pump is relatively simple and inexpensive. The installed cost of the device can be less than $500, depending upon the job specifications. “All you have to do is just unscrew the old one and put the new one in,” Peace said.
The pump is available in a range of sizes and various construction materials, which can be tailor-made to the application and the customer’s preference.
Peace said the pump also might be used in flow equalization, sludge mixing, sludge transfer, chemical dosing, and many other applications outside the wastewater treatment field.
“This is the only thing out there that will work on these small flow situations. I know the frustration of these operators. They are sometimes blamed for their inability to control something that up to now could not be controlled,” said Peace.
First Application
Peace said the first application occurred near his hometown, Eagle Rock, Virginia, on a 20,000 gpd package plant. The plant had received a new permit that required a stringent nitrogen limit.
“They were trying to increase the sludge age,” Peace said. “As they tried to raise the
concentration, they had difficulty in maintaining a solids inventory. I have seen that problem with every package plant I have operated.
“A few months before, I had come across material on this new pump at a conference a friend had attended in North Carolina. The part that intrigued me was the air pump that was fully controllable and could be set to whatever rate you needed to feed the plant and return the sludge.”
Peace said that after they installed the Geyser Pump at the Eagle Rock plant, the response was immediate. “It was like throwing a switch. The effluent was considerably lower in solids. A few months later, the ammonia level was less than 1 mg/L for total suspended solids, and biochemical oxygen demand was in the single digits,” said Peace. “Today, the plant is still perking along, doing better than ever. In the meantime, we have installed pumps in six other package plants.”
Hello Operator
Paul Peery, utility supervisor for Botetourt County Public Works Department package plant, believes the Geyser Pump will make a long-lasting impact in the package plant industry. “I think the pump has made a big improvement in the package plant treatment process,” said Peery, who oversees the Eagle Rock facility and has been an operator for 12 years.
“Our plant was the first wastewater treatment plant where the Geyser Pump was used. Basically it was installed on a trial-and-error basis to see how it was going to handle. I wasn’t sold on it in the beginning. I was concerned that it would stop up, but it does an excellent job. I don’t think you can stop them up.”
Ammonia levels have gone down at Eagle Rock, a 10-year-old, 20,000 gpd package plant, since the pump’s installation six months ago. The plant’s levels went from 7 milligrams per liter to less than 0.2 after installing the pump, allowing the plant to more than meet their set limit.
“What we ran into is pretty much what every package plant runs into. There was no accurate way of controlling the sludge rate without stopping up the system,” said Peery.
“The thing about the Geyser Pump is it gives you the ability to better control the return sludge rate versus package plants with the air lift return design. You can set it to pulse at a wide variety of second or minute intervals. The control of air pressure sets the length of time it takes for the sludge to fill the vault of the pump, increasing the retention time in the clarifier. The longer retention time in the clarifier helps reduce the ammonia levels.”
Peery said the pump can be interchanged into the design of different systems “easily and affordably.” He added that he would recommend the pump to other package plant operators.
Arville Anderson, who operates a wastewater treatment package plant in Middlesborough, Kentucky, agrees that the pump is a success. “It appears to be working really well for us,” said Anderson.
“We’re a small package plant with a flow of 5,000 gpd. We had been having problems regulating the return sludge flow. Since we installed the new pump, we are able to reduce the flow without stopping the line. We couldn’t regulate our return flow before. We just had a constant flow. If we would try to shut down the lines, they would clog. It has given us a more consistent return and better looking effluent.”
Anderson said the pump has been in place for three months at the 15-year-old facility, located in Southeastern Kentucky.
Anderson could not recall the exact price of the pump installation but said it was not very expensive. “We’ve not only saved money, but it has allowed us to meet our effluent limits a lot easier for our permit.
“I think it’s really made a big impact on operations of the plant,” said Anderson, who has worked at the residential wastewater facility for the past 10 years.
“I recommend it for any small treatment plant.”
For more information, contact Peace at (540) 473-2867 or e-mail him at Geyserpumps@aol.com.