The city of St. Helens, Oregon, and the town’s major industry, Boise Paper, share the wastewater treatment plant as well as the NPDES permit. To meet their goal of cost effective operation, officials installed solar-powered circulation mixers from SolarBee, Inc. and cut aeration runtime costs more than 50 percent. As a result of the initiative, the City of St. Helens received an Oregon Leaders Award for industrial energy efficiency.

Solving odor problems in wastewater treatment ponds should begin with a few investigative questions: How was the pond designed? Has the operation of the pond changed over the years? What is the purpose and operational theory of each pond, and have ponds been added or closed? Why are odors apparent on some days and not others? Understanding these “hows” and “whys” will provide clues to successfully solving odor problems in a variety of wastewater treatment plants.

To prevent water aging and breakdown of disinfection chemicals, municipal water system operators have tended to rely on normal cycling of water in and out of the tank.  However, this “passive” mixing” is often not enough to prevent temperature stratification and its associated problems.  An alternate solution is continuous, active mixing.  When combined with periodic chemical boosts, continuous, active mixing has been shown to eliminate sampling inconsistencies, thermal stratification and water aging.

To prevent water aging and breakdown of disinfection chemicals, municipal water system operators have tended to rely on normal cycling of water in and out of the tank. However, this “passive” mixing” is often not enough to prevent temperature stratification and its associated problems. An alternate solution is continuous, active mixing. When combined with periodic chemical boosts, continuous, active mixing has been shown to eliminate sampling inconsistencies, thermal stratification and water aging.

Electrical aeration is used intensively in reactor basins at activated-sludge wastewater treatment plants to supply the mixing and oxygenation needed for digestion. Officials at Eden, North Carolina, investigated the ability of solar-powered circulation technology (SPC) to reduce their operational expense.

The goal was to meet National Pollution Discharge Elimination System (NPDES) standards while reducing grid-powered aeration and operating a single SPC unit in one basin. Study objectives were to compare effluent water quality parameters and grid-power usage and cost during one year of SPC treatment with comparable data from the immediately preceding year when only aeration was used.

Delivering water with stable and predictable concentrations of disinfectant can be a challenge for municipal engineers. Faced with poor circulation and loss of chlorine in a 4 MG potable reservoir, engineers at a central Illinois town found a solution to the problem by circulating the water using solar-powered technology. Circulation improved the consistency of disinfectant while helping to reduce the cost of chemicals and provided a more manageable system for employees to operate.

The New Hampshire Department of Environmental Services studied three wastewater treatment plants to evaluate the ability of solar powered circulation (SPC) technology to reduce or eliminate the need for grid-powered aeration. SPC was expected to supply all required mixing and at least some of the required oxygen through diffusion at the air-to-water interface and entrainment of photosynthetically produced oxygen. As a result, operational costs declined as SPC reduced or eliminated the need for aeration while maintaining or improving effluent quality. This white paper describes the water quality, odor control, sludge thickness, and kilowatt-hour (kWh) consumption and expenditure data 1 year prior to, and 1.25 years during, SPC treatment.

When the San Francisco Public Utilities Commission (SFPUC) transitioned to chloramines as a secondary disinfectant, the utility anticipated nitrification problems at several oversized distribution reservoirs. The largest distribution reservoir, Sunset Reservoir South Basin, was chosen as a test site for evaluating methods to thoroughly mix the water. One of the tests assessed the ability of a single SolarBee unit to mix, destratify and disperse chlorine in Sunset Reservoir. The SFPUC concluded that the single mixer could circulate water, break thermal stratification and disperse chlorine throughout the reservoir.