News

Picture-Perfect Mixing

Water and Wastes Digest
Fri, 04/22/2011
By Patrick J. Schnaidt

SolarBee mixers improve water quality for Yuma, AZ residents

Whoever said tanks were just for holding water? In Yuma, Arizona, the city’s three potable water tanks are works of art. Featuring colorful murals of the local landscape, the 50-foot high and 100-foot wide tanks are a drive-by gallery on display to anyone on Interstate 8. What’s more important, of course, is the quality of the water inside the tanks. Thanks to SolarBee mixers, Yuma’s drinking water is now picture-perfect.

It hasn’t always been that way, according to Bill Barbieri, chief plant officer for Yuma’s water department. The city’s tanks—each with a maximum storage capacity of 3 MG—had problems with short-circuiting and stratification. The result of inadequate mixing, these problems led to uneven water age and inconsistent chlorine residuals in the tanks.

“We never had a problem meeting compliance regulations, nor were taste or odor an issue,” said Mr. Barbieri. “But we were creeping up on our levels of THMs (trihalomethanes, a disinfection by-product) and we knew the tanks had stratified. Because of short-circuiting, we didn’t have full use of the capacity of the tank.”

At first, city officials considered installing diverters on the inlets. Instead of directing water straight into the tank, a 45-degree elbow would divert it higher up into the tank. However, upon further study, officials concluded that such a solution would be cost-prohibitive and ineffective.

Then Mr. Barbieri learned of SolarBee mixers while visiting Las Vegas for a conference. SolarBee mixers are installed in the water system there. After further study, the City of Yuma installed one SolarBee SB2500v12 unit in each of the three tanks.

Energy-efficient solar technology

The solar-powered, floating SolarBee mixers in Yuma’s water tanks operate day and night with a permanent-magnet, low-voltage motor and an onboard battery system for continuous, energy-efficient water quality improvement. The unique SolarBee flow pattern ensures consistent dispersion of disinfectant throughout the tank volume, including constant replacement at the walls, in the bottom three feet of the tank and at the floor, where bacterial growth would otherwise flourish due to lack of disinfectant. By actively mixing Yuma’s potable water storage tanks, SolarBee mixers help ensure uniform distribution of disinfectant, eliminate thermal stratification and prevent stagnation and short-circuiting. In addition, well-mixed tanks eliminate the need for energy–intensive deep-cycling or tank flushing.

“We liked the greener approach of solar-powered mixing,” said Mr. Barbieri. “The tanks are in an isolated area with a limited amount of electrical power. We also liked the fact that the SolarBee mixers are capable of stand-alone operation.” An added plus was SolarBee’s BeeKeeper service program, which provides on-site maintenance, power system upgrades and repair of damaged equipment, even if the damage is caused by an act of nature.

Since the SolarBee mixers were installed, the city’s own comprehensive monitoring has confirmed that water temperatures are uniform throughout each tank, stratification issues have been resolved, and there is no longer any short-circuiting. The city uses less chlorine for disinfection, and chlorine residuals are now more consistent. Furthermore, average concentrations of THMs dropped from 71 μg/L to 46 μg/L in the first two years since the SolarBee mixers began circulating tank water.

Yuma water officials constantly look for ways to deliver the highest-quality water to residents. With SolarBee mixers, they are assured that the water supply is not only safe and tasty, it’s even sustainable. That idea is pretty as a picture.

About SolarBee

SolarBee Inc. provides mixing, disinfectant boosting, and THM removal technologies to solve water quality problems in the potable water storage market. SolarBee’s award-winning and patented long-distance circulation technology (LDC) thoroughly mixes potable water storage tanks, eliminating stagnation and thermal stratification, providing a uniform water age, consuming less disinfectant, and producing fewer DBPs. SolarBee offers a complete line of cost-effective mixers in grid-powered and solar-powered options to mix any tank shape and size. SolarBee’s LDC can also be applied to lakes and raw water reservoirs, wastewater lagoons and basins, and other water reservoirs.