Thank you for your interest in Geyser Airlift Pump.

This page introduces a basic technology background of the Geyser Airlift Pump, the Geyser Ejection Pump and the Geyser Hybrid Pump, which are revolutionizing the pump industries.

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Return Activated Sludge and Clarifier Performance

Return Activated Sludge (RAS) is a very important factor to operate sewage treatment plants. However many professional engineers and manufacturers are neglecting this fact, and airlift pump or mechanical pumps were installed for RAS, as they are readily available. A typical example is shown in Fig. 1. This is a picture of clarifier of Cedarville sewage treatment plant in Ohio in 2001. Supernatant was turbid and scum was observed. 6" airlift pumps were installed for improvement. Fig. 2 shows the picture of the clarifier 12 hours after the installation of 6" Geyser Pump. The improvement was quick.

Merits of Geyser Pump for RAS

Problems in Airlift Pump for RAS

Airlift Pump is not for RAS

How is this quick improvement possible? The key word is TURBULENCE in the clarifier. When sludge is returned from the clarifier to the aeration tank, the hydraulic loading to the clarifier is increased from the loading of the influent sewage flow. According to the theory of Activated Sludge or Extended Aeration System, the RAS flow rate should be 50% to 150% of the influent flow rate. To have a good clear supernatant, and to have a thick sludge accumulated in the clarifier, the clarifier has to have a certain surface area, depending upon the design flow rate. For example, if the influent flow rate is 100,000 GPD, the RAS flow rate is from 50,000 GPD to 150,000 GPD. That is, the flow rate to the clarifier is 150,000 GPD to 250,000 GPD. Based on these data, clarifier has to have a surface area of 188 to 417 square feet. Most of the clarifiers have the similar criterion in the world. This comes from the parameter called "Surface Settling Rate". This is the most important parameter to design clarifiers and it should be between 600 to 800 GPD/square feet.

If RAS flow rate is reduced to less than 50% of influent flow rate, sludge retention time in the clarifier becomes too long and the clarifier will be covered by scum. If RAS flow rate is increased to more than 150%, too much water flows to the clarifier, which exceeds the design capacity of the clarifier. This is called "hydraulic overload to the clarifier". Water and sludge is agitated due to turbulence, then supernatant becomes turbid and sludge blanket is swollen. When sludge blanket is only 1 foot to 2 or 3 feet from the water surface, sludge is often carried over to the effluent weir. Typically, this "hydraulic overload to the clarifier" occurs to most of the small to medium-size sewage treatment plants, because the clarifier is equipped with airlift pump. Airlift pump is easy to fabricate and inexpensive for manufacturers. Therefore, airlift pump is the standard as the RAS pump in the world. But airlift pump creates too much flow and the "surface overflow rate" exceeds 1,000 GPD/square feet easily.

Findings from the field test by Ohio EPA reveals the operational problems caused by airlift pump.

Field Experiment with Ohio EPA

Keith Kroger and Jon van Dommelen with Ohio EPA visited a nursing home in 2001 and checked the performance of the package treatment plant there. The design flow of the plant is 5,000 GPD. 2" airlift pump was equipped in each hopper-type clarifier. The operator of the plant mentioned that there were problems of frequent sludge carryover and turbid effluent.
They found the following facts:
- RAS by 2" Airlift pumps was 52,000 GPD and 64,000 GPD
- No supernatant in the first hopper and 1.5 feet of supernatant layer in the second hopper.

 

 

 

 

Fig. 1. Before installation of Geyser Pump. Turbid supernatant and scum was observed in the clarifier. It was revealed that airlift Pump created this mess.

 

 

 

 

 

 

 

 

 

According to the diagnostic evaluation by Ohio EPA, too much RAS flow rate is the cause of the problems. The airlift pumps were replace with 2" Geyser Pumps. Twenty minutes after the installation, the same parameters were checked.

Fig.2. 12hours after the installation of Geyser Pump. Transparency of the supernatant became over 2 feet in this short period.

 

 

 

 

 

 

 

 

 

 

Important Questions

A pilot-scale experiment device was fabricated to find out answers for these questions. Two 30-gallons aquarium tanks were separated to four chambers, selector, two aerobic chambers, and clarifier. One clarifier is equipped with airlift pump and the other with Geyser Pump. Clarifier is two-hopper style. When airlift pump or Geyser Pump is operated, water overflows from two aeration chambers and clarifier by gravity.

 

Flow rate of 2" airlift pump and 2" Geyser Pump were compared at the site with Ten State Rule. The result is summarized below. It was revealed that 2" airlift pump equipped as a standard design by a manufacturer did not work, as the lowest flow rate was 6 times the required flow rate by Ten State Rule. Is it design flaw? Well... Engineers and manufacturers did not know what was happening at the site. Another important fact is that proper equipment like Geyser Pump was not available until 2000.

 

 

 

 

 

 

 

Overall outlook of the pilot-scale plant
Mixing Geyser Pump and diffuser in Selector

 

 

 

 

 

 

 

 

 

 

Airlift Pump in Clarifier
Geyser Pump in Clarifier
Mixing Geyser Pump in Selector
With the cooperation of Ohio EPA, this device was set at a sewage treatment plant at Delaware County in Ohio. Real sludge from the aeration tank of the plant was poured in each tank and the RAS flow rate of Airlift Pump and Geyser Pump was adjusted to find the influence to the clarifier.

 

 

 

 

 

 

 

 

 

 

 

 

 

RAS flow rate was set to three values, 1000, 800, and 350 GPD/square feet and the sludge blanket were taped in the following video. You can see how the depth of sludge blanket is related to the RAS flow rate.

 

 

 

 

 

 

 

 

 

 

 

Testimonial

Over 1,000 Geyser Pumps have been installed for the replacement of airlift pumps since summer 2001 throughout the U.S. They have a track record of success at improving plant performance and reducing maintenance time. Here are comments by operators.

Keith Kroger, an Environmental Specialist of Ohio EPA
"...The Geyser airlift pump can provide the operator a wider range of control over the return sludge rates and possibly reduce the clogging events of standard airlift designs"
"The Geyser airlift system should be incorporated into the Ohio EPA's Division Surface Water's review guidance (Green Book) for design of extended aeration package plants

Indiana Department of Environmental Management (IDEM), gAlternative Technologies Exhibited at Wastewater Conferencesh, Operator Examiner -News for Wastewater Treatment Professionals, Fall, (2004) .
"Air-lift pumps for return activated sludge have been a problem because they easily plug up if not operated at full force. gGeyser Pumpsh are alternative air-powered pumps that provide better flow control and improved lift. Unlike air-lift pumps that raise sludge with a continuous release of fine bubbles, air accumulates in a bell-housing before being released in a single, large pulse that lifts the sludge with even greater force. Since each pulse has the same force, the flow rate is controlled by raising or lowering pulse rate without reducing the amount of lift. This enables the operator to set a return rate that increases solids return while reducing return flow, thereby effectively reducing hydraulic loading on the plant. Geyser Pumps can be retrofitted to replace pre-existing air-lift pumps. For more information, visit the Web at www.geyserpump2.com. "

Larry D. Cole, Superintendent of Greene County, Ohio
"I haven't seen this clean water in this plant (of Cedarville, OH) for a long period. It is a good product.h

Richard Weigand, Coordinator of WV Environmental Training Center
"Two innovative new air lift pumps have been installed at the Cedar Lakes package plant. The project was part of a recent I-S Certification course at the Environmental Training Center. The units, called Geyser Pumps by their inventor Sam Kondo, look like metal mufflers and were easily retro fitted to existing clarifier piping. The Geyser Pump design appears to be simple and effective ? it greatly improves RAS flow control, especially at low flows. This can really help package plant performance where excessive RAS flows are a frequent problem."

Paul Peery, Utility supervisor for Botetourt County Public Works Department Package Plant in Virginia
"I think the pump has made a big improvement in the package plant treatment process. 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."

Warren Peace, Professional Engineer and consultant to municipal and industrial wastewater treatment plant operators in Virginia and Kentucky.
"Since seeing the Geyser Pump in action for the first time several months ago, I have become convinced that it is the solution to one of the most difficult problems faced by operators at small and medium-size package plants. Existing airlift pumps do not allow for a predictable and controllable rate of flow from the clarifier to the aeration tank. The Geyser Pump gives them the same measure of control over the return sludge rate as operators of a full-size plant. In practice, it effectively increases the size of their clarifier, something every operator would love."

Terry Miller, operator of Cranbrook Village, a 10,000 gpd wastewater package treatment plant serving a mobile home park in Guilford county, NC
"Initially, we were skeptical about the Geyser Pump, but we were willing to try it. We were in for a big surprise. Within 30 minutes after installing it, the water in the clarifier started clearing up. We became true believers when the effluent data started coming back. Within one month, our plant went from BOD values in the range of 6-10 to less than 2, and Ammonia Nitrogen as high as 26 to less than 1."

 

 

Video download for three values of RAS flow rate