Aeration & Mixing

In 2014-15 Water Corporation constructed Stage 1A of the East Rockingham WWTP, which included two (2) Oxidation Ditches (ODs). Each OD with approx. dimensions 115m L x 25m W x 6.1m D at (Top Water Level) TWL, was fitted with two (2) pier mounted surface aerators. Initially each OD would treat 3 ML/day increasing to 10 ML/day of screened & degritted sewage. The system was designed so that in subsequent upgrade stages Primary Settling Tanks will be installed upstream of the ODs, that will allow future treatment of up to 20 ML/d per OD. The NSA-series Low Speed Aerator model NSA5-300B (220 kW) supplied by DBS Manufacturing was selected for this project due to its low power usage and demonstrated performance in many similar applications.

A large Victorian Municipal Water Authority was upgrading its wastewater lagoons to cater for additional loads and required an aeration system to improve the wastewater treatment process. Key requirements for the aeration system included: • Shallow draft as the lagoons are only 1.5m deep • Quiet operations due to proximity of local residents (<70DbA) Aeration Demand requirements • BOD (Peak) – 231 kg O2/d, Actual Oxygen Transfer Rate (Peak) – 15 kg O2/hr

Renison Tin Operation is the largest tin producer in Australia, one of the world’s largest and highest-grade tin mines and through the Metals X equity interest, one of the few publicly held tin projects in the world. Their ore leaching plant incorporates several thickeners where ore-liquid slurry is densified to a slurry containing most of the solids, and an overflow of essentially clear water. Each of the 20 ft diameter thickeners is fitted with an internal rake that is turned and lifted by an electro-mechanical drive mounted on a bridge that spans the thickener tank. The old Eimco Process Equipment W36 drives with power lift installed on the thickeners had become unserviceable, which directly impacted mine production. Repairing the drives was possible but expensive and required extended plant down-time that would interrupt mining operations. The mine opted for complete brand-new DBS replacement drives that are direct bolt-in replacements for the existing Eimco drive units. The DBS replacement drives were found to be more economical than rebuilding the old drives and required less plant downtime to install. The mine installed DBS replacement drives for two leaching plant thickeners in 2020, and for another two thickeners in 2021.