As part of the Tahuna Wastewater Treatment Plant Stage 2 Upgrade, Pump Systems Ltd was awarded a contract to design and supply two Rotamix sludge mixing systems to mix one 1,000 m3 Thickened Waste Activated Sludge (TWAS) Storage Tank and one 300 m3 Pre-Gravity Belt Thickener (GBT) Flow Balance Tank. The new process at the plant meant that sludge levels in each tank would continuously vary throughout the day. To accommodate this, extra-low-profile Rotamix nozzles were selected and variable speed drives recommended to control the flow output from each Vaughan mixing pump. Detailed CFD simulations carried out prior to installation predicted excellent mixing of both tanks. The results showed that the mixing systems would achieve active volume mixing rates of between 91.5 and 97.8 percent, surpassing Vaughan Co.’s requirement of 90% or greater active volume mixing for all systems.
This custom engineered, 16 foot long Vaughan vertical recirculating chopper pump has been running reliably at the Green Island WWTP, Dunedin, New Zealand since it was supplied in the year 2000. The pump handles incoming sludge cake and wastewater with dry solids concentrations up to 20%. Adjustable levers at surface level allow plant operators to aim the pump’s integrated discharge nozzle to direct flow to different areas and levels of the pit to prevent solids from settling out. A three-way valve then allows flow to be switched to the main discharge line for complete pit pump out as required. The client, Dunedin City Council, decided to purchase a complete replacement unit in 2013 and the original pump is now held as a standby unit.
As part of a major upgrade works at the Christies Beach WWTP in South Australia, Pump Systems designed and supplied three Vaughan Rotamix Process Mixing Systems for mixing sludge in the plant’s three 21.3 metre diameter anaerobic digesters. Two of the Rotamix systems would replace older gas mixing equipment in existing Digesters 1 and 2, while the third Rotamix system would be installed in a newly constructed identical Digester.
For more than a decade, the Rosedale Wastewater Treatment Plant on Auckland’s North Shore has been using Vaughan horizontal end suction chopper pumps to recirculate sludge in the plant’s four anaerobic digesters. With advances in technology over the years, the originally installed Vaughan HP-Series chopper pumps have been upgraded to the new and improved Vaughan E-Series design.
Pump Systems Ltd’s local representative in Melbourne – Metaval Consolidated Pty Ltd, completed a project at the Mt Martha STP for the supply of four new Vaughan vertical dry pedestal chopper pumps for digester sludge. The equipment was sized to replace existing macerators and PD pumps that were prone to clogging. As rag and fibrous material was a known issue at the plant, the pumps were fitted with 18.5kW, 4-pole speed motors to provide plenty of chopper power and torque in case of heavy solids loadings.
Pump Systems completed an interesting project at the Palmerston North City Council’s Totara Road WWTP for a state-of-the-art waste reception facility, which takes a combination of food wastes, raw septage and piggery wastes before being processed and injected into the digesters at the plant. The introduction of fats, oils and greases (FOG) into anaerobic digesters can greatly enhance methane gas production. Vaughan Chopper Pumps were preferred for the site due to their proven ability in handling difficult solids and to eliminate the risk of clogging.
Pump Systems Ltd, working in association with W2W Alliance successfully completed a project for Water Corporation in Western Australia. The scope included the design and supply of two Vaughan Rotamix process mixing systems for two combined thickened sludge tanks, a new process at the plant. Due to the unique sludge characteristics, a customised mixing design was supplied based on extensive CFD modeling work.
Plagued by poor mixing and foaming problems, the Tauranga City Council required a new approach that would provide better mixing for their two 15.5 metre diameter digesters. Pump Systems was called on to design and supply two Rotamix nozzle mixing systems to replace the outdated gas mixing equipment and to provide improved overall active volume mixing. Unlike recessed impeller or screw impeller pumps, the unique chopping action of the Vaughan chopper pump ensures reliable long term performance by continuously preconditioning incoming sludge and thereby eliminating the risk of clogging.
The Greasy Wastes Receiving Facility at the Jurong Water Reclamation Plant in Singapore required a proven solution for mixing thick and heavy plant sludge containing high levels of fats, oils and grease in two 8 metre diameter storage tanks. The sludge was to be kept in a fully mixed and preconditioned state in order to eliminate material floating on the surface. Pump Systems designed and supplied two Rotamix systems, each comprising of three Rotamix nozzle assemblies and one heavy duty Vaughan SP8N10 self priming chopper pump.
In 2006, Pump Systems Ltd supplied two Rotamix process mixing systems for an upgrade project at West Camden WWTP in Sydney, Australia. The mixing systems were designed to mix two identical 10 metre diameter flow balancing tanks containing undigested Thickened Waste Activated Sludge (TWAS). Innovative through-the-wall style Rotamix nozzles were used to eliminate the need for internal pipe work and to provide higher mixing efficiency over a range of levels.