In 2018, the Beaufort Jasper Water and Sewer Authority (BJWSA) comprehensively upgraded the Hardeeville Water Reclamation Facility (WRF), expanding the design flow capacity from 1 to 2.7 MGD. Designed by HDR, the upgrade also enhanced the facility’s nutrient removal efficiency, improving the water quality of the Savannah River.
BioMix Compressed Gas Mixing System operating during startup of anoxic selectors.
0٫09
hp/1,000 FT3 mixing efficiency
60
% energy savings
Challenge
HDR and BJWSA evaluated several mixing technologies, searching for one that provided easy adaptation to changing mixing requirements, required minimal maintenance, and offered the lowest operating cost.
Solution
EnviroMix’s BioMix Compressed Gas Mixing System was integrated into two processes — the equalization basin and the activated sludge anoxic selectors — that have different hydraulic characteristics, variable operating levels, and application specific nozzle density and firing parameters.
BioMix is a unique solution in that both systems receive mixing air from a common, centralized compressor system, while mixing parameters and operating efficiency are automatically controlled by system control logic and instrumentation feedback.
BioMix nozzle headers are designed for any tank geometry or configuration.
The liquid level in the flow equalization basin varies, whereas the liquid level in the anoxic selectors remains constant. The BioMix control system automatically maintains a fixed air flow rate to individual processes and controls the volume of air released to the air control valves and corresponding header supply piping. This feature is utilized to optimize operating efficiency, as well as to provide increased, localized mixing intensities when operating levels drop to the low end of the expected operating range.
The BioMix system also requires minimal maintenance. All in-tank components are maintenance free, non-clogging, and self-cleaning. Electrical requirements are limited to the power needed to operate the air compressor and the valve modules. Systems require minimal maintenance of out-of-tank components (compressors, receivers, and air control valves) in controlled environments.
Results
The BioMix system offered BJWSA the lowest operating cost of any available mixing technology. When compared to mechanical mixing, the plant’s costs were reduced by 74% for the equalization basin and 66% for the anoxic selectors.
The Hardeeville WRF demonstrates how the BioMix Compressed Gas Mixing System provides a high degree of operational flexibility and is an energy efficient alternative that plays a key role in biological nutrient removal.