Plant utilizes efficient mixing technology

Problem: The 4 mgd activated sludge wastewater treatment plant in Albion, Michigan, has two parallel trains that make it easy to adjust one side while holding the other constant. Kent Phillips, plant superintendent, hypothesized that modulating mixer speed would reduce dissolved oxygen, maintaining mixing while reducing surface churning, thus improving biological phosphorus removal and allowing him to reduce chemical and energy use. After promising test results, he began experimenting and decided to install a more efficient mixer.

Solution: The facility acquired a Flygt 4200 Series mixer to replace the existing 2 hp mixer, which drew a continuous 1.3 kW. The new mixer has an IE4 equivalent permanent magnet motor, enabling previously unobtainable motor efficiency. The team can run the mixer at a much lower speed and still maintain effluent quality.

Result: After experimentation, Phillips reached acceptable agitation at less than 0.2 hp. In the end, he found he could turn the unit all the way down to 0.1 kW — 8 percent of what the old mixer used — and still have satisfactory mixing. 855-995-4261; www.flygtus.com

Mixing technology helps maintain temperature in reservoir 

Problem: The Reading Area (Pennsylvania) Water Authority sought a solution to mix a 15-million-gallon water reservoir (300 feet diameter) to maintain uniform temperature and chlorine residual. The system needed to be in its own all-weather enclosure.

Solution: BCM Engineers designed a Pulsed Hydraulics (PHI) system with 16 bubble-forming plates and two PHI-500 enclosures that each house PHI 360 components and a 15 hp compressor. Using two compressors connected and controlled by the PHI software limits the start surge power to prevent the plant’s electrical infrastructure from overloading.

Result: Temperature readings from predetermined test points showed a temperature differential of 0.1 degree F. Before mixer installation and startup, the reservoir water was stratified and readings showed a 6 degree F temperature variance. 800-641-1726; www.phiwater.com

Sliding Frame offers loading reliability

Problem: The Puyallup (Washington) Wastewater Treatment Facility has made a series of upgrades to its biosolids facility. One issue was consistent truck loading. The 8 mgd facility, with a small staff, needed “set it and forget it” equipment requiring minimal maintenance and operator support.

Solution: They chose the Schwing Bioset Sliding Frame with 170 cubic yards capacity and the required loading consistency. A truck driver pulls into the loading bay, causing gates to open and fill the truck at multiple points. The system is integrated to meter biosolids into each truck and uses load cells in the automated loading sequence to avoid overfilling trucks and overweight trucks. It is nearly maintenance-free and requires no additional staffing.

Result: Facility management was happy with the low-profile design and the system’s vertical sidewalls that maximize usable space. This profile allowed the system to be built immediately next to the solids building and still accept the conveyor feed system, which originates from a floor below. 715-247-3433; www.schwingbioset.com