Air-Powered Mixer Minimises Maintenance, Reduces Aeration Intensity in Wastewater Treatment Plants

Combining proven long-distance circulation technology with clog-free, air-powered pumping, the new GridBee AP Air-Powered Mixers from Medora Corporation (USA) are ideal for mixing activated sludge basins, both aerated and anoxic, having high total suspended solids (TSS). In aerated basins during off-peak flows, the aeration intensity can be reduced considerably to match the lower oxygen demand without losing the TSS, leading to substantial energy savings. In raw water ponds, lakes, and estuaries, the AP mixers can provide blue-green algae (BGA) control and other water quality improvements.

“Unlike mechanical mixers, the air-powered mixers have no impeller and therefore no moving parts to maintain, and no electricity in the water,” said Joel Bleth, president, Medora Corporation. “The three models have a very high flow rate relative to other air lift pumps on the market, and are self-cleaning. So if stringy material or a rag comes up the intake tube, it flows right through the machine.”

Located just beneath the water surface, the air pump efficiently pumps up to 1,700 gpm while using only 2.3 psi of air pressure (see video). Air can be supplied by the plant's existing air system or by Medora’s optional on-shore blower. Medora’s on-shore blower assembly is housed in a sound-attenuated enclosure and includes a drive system, blower motor, ventilation fan motor air filter, and operating gauges.

GridBee AP mixers come in three standard sizes with 600, 1,100 and 1,700 gpm direct flow. Compact and lightweight, the mixers are easily installed by plant personnel.

Applications for lakes, raw water and storm water

GridBee AP mixers can also be used to control BGA and odours in municipal ponds, lakes and raw-water reservoirs. Their low profile and small footprint are unobtrusive, and with no electricity in the water, the mixers are safe for use around people and pets. In stormwater ponds, thorough mixing helps reduce nutrients and increases detention.