'Mayors Water Council Winter 2008' by Unknown

Mayors Water Council

Newsletter of the Mayors Water Council of The United States Conference of Mayors

Winter 2008

START UP from page 6

COST ANALYSIS

Current

SDOX-300 Annual Savings

This equipment, which uses liquid oxygen (LOX) first super-

Oxygen Consumption, cu ft/yr 1,754,892

133,643

saturated into water rather than directly into the effluent itself,

is much more efficient than existing equipment. Historically, the

Cost per 1000 cu ft

$8.62

Noland plant has required approximately 40 inches (48,781

Oxygen Cost per Year

$15,127.17

$ 1,152.00

$ 13,975.17

cubic feet) per day of LOX from the tank when it is in use.

During the testing period, usage dropped to approximately

Electrical Consumption, KWH

6,600

3000

4 inches (4,878 cf) per day. The expected savings in LOX at

Cost per KWH

$ 0.06

Noland will pay for the investment in less than five years with

Electrical Cost per Year

$ 396.00

$ 180.00

$ 216.00

many years of savings to follow.

Given the physical success of the test, the ease of mainte-

Total Annual Savings

$ 14,191.17

nance, and the cost savings, OMI staff approached the Water

Purchase Cost (Installed)

$ 66,460.00

and Wastewater Director recommending the BlueinGreen sys-

tem be purchased. The Director concurred, and presented this

Time to recoup full purchase cost

4.7 years

proposal to the City Council Water and Sewer Committee, which

has oversight on water and wastewater policy and activities in

the City. The Committee approved it to be presented to Mayor

Dan Coody and the full City Council for a decision. In the Com-

mittee and Council review process, an unexpected ally came

its pressure tank and supplied a duplicate suction pump to

forward; the president of the Fayetteville Economic Development

supply water to the system to increase reliability. An electrical

Council spoke at the Committee and Council meetings in favor

supply line was connected from nearby post-aerator to the

of the purchase. This was the first purchase for this locally based

equipment to supply power.

startup company, and he was hoping it would be the catalyst to

BlueInGreen was able to maintain dissolved oxygen above

help them truly enter the market and establish themselves.

permitted levels consistently while using only a tenth of the

The City purchased the BlueinGreen SDOX-300 unit at the

amount of LOX. This was done without using the post aera-

Noland WWTP on the basis of cost savings, but the purchase

tors. This would create a large LOX savings and a smaller

created other benefits as well. The partnership with the Uni-

electrical savings (even though electricity was still used to

versity of Arkansas was enhanced. A local start-up company

power the water pumps, the horsepower required was much

achieved its first sale. An innovative new system proved its

less than for the normal operation of using both mechanical

effectiveness and was introduced into the industry. Finally, our

post aerators).

wastewater utility and the City of Fayetteville again led the way

Under normal conditions, LOX is introduced into the effluent

in conducting operations in the most environmentally sustain-

flow via course-bubble diffusers at the beginning of the efflu-

able fashion, ultimately saving manufacturing, transportation,

ent channel. A significant portion of that would be released

and electricity demands.

to the atmosphere as soon as it was introduced into the

channel, similar to bubbles of the top of a soft drink. Using

Testing Process and Technical

the BlueInGreen system, the micro bubbles slowly rise to the

surface, thus extending the time the oxygen was in the water

Observations

and achieving a much greater oxygen transfer efficiency.

BlueInGreen tested the SDOX-300 system in the effluent chan-

The oxygen level in the channel was easily adjusted to

nel to determine whether the system could reduce LOX and

achieve the desired level with much greater precision than

energy while maintaining a dissolved oxygen level above

with the previous system, further enhancing the efficiency.

the permitted limit of 10 mg/L. The system was set up to use

Other than normal maintenance checks on the equipment, it

treated plant effluent from the postaeration basin as the sup-

appears to be a fairly hands-free system.

ply water to inject into a pressure tank, supersaturate it with

The components used to make up this system are off-the-shelf

Liquid Oxygen (LOX), and release it into the effluent channel.

and should therefore be readily available for future necessary

BlueInGreen connected a line from the existing LOX tank to

repairs.