Wastewater treatment plant replaces unreliable digester gas mixing with Vaughan Rotamix

As a result of poor mixing and troublesome foaming problems caused by outdated gas mixing technology, the Tauranga City Council required a new approach that would provide better mixing for their two 15.5 metre diameter digesters. Pump Systems Ltd was called on to design and supply two Vaughan Rotamix digester mixing systems that would replace the failing equipment and provide improved overall mixing performance.

Being a fully operational plant, one digester would remain in service while the other was retrofitted with the new Rotamix mixing equipment. Before this could be done, all existing central and peripheral gas sparges and edcuctor tubes had to be removed. Two double floor mounted Rotamix nozzle assemblies were then fixed permanently in position at predetermined angles within the digester. Glass lined and hardened to Rockwell 73C, each Rotamix nozzle assembly comes with a full 10 year replacement warranty, and with no moving parts inside the tank the result is a cleaner, more dependable mixing design.

Each Rotamix system would be powered by it's own externally mounted Vaughan HE6W8 end suction mixing pump, direct coupled to a 30 kilowatt, 4-pole speed electric motor. Unlike recessed impeller pumps or screw impeller pumps, the unique chopping action of the Vaughan chopper pump ensures reliable long term mixing performance by constantly preconditioning the sludge and thereby eliminating the risk of clogging.

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Rotamix sludge mixing systems supplied for new greasy wastes facility in Singapore

The new Greasy Wastes Receiving Facility at the Jurong Water Reclamation Plant in Singapore required a proven solution for mixing difficult plant sludge containing high levels of fats, oils and grease. The sludge was to be kept in a fully mixed and preconditioned state in order to eliminate material floating on the surface. To solve the problem, Pump Systems Ltd offered two Vaughan Rotamix nozzle mixing systems.

For mixing the two 8 metre diameter below ground sludge tanks, each Rotamix system comprised of three Rotamix nozzle assemblies and one heavy duty Vaughan SP8N10 self priming chopper pump fitted with a 45 kW, 985 rpm electric motor. By using variable frequency drives, the mixing systems are designed to operate over a range of capacities to accommodate for changing sludge levels. Within the tanks, the glass lined and hardened Rotamix nozzles provide calculated high velocity mixing patterns required to keep solids in suspension, and all with no moving parts.

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Lackeby non-clog sludge heat exchangers installed at local wastewater treatment plant

Pump Systems Ltd have recently supplied six large Lackeby sludge heat exchangers as well as other specialist sludge pumping equipment to a wastewater treatment plant in Christchurch, New Zealand as part of a new plant room upgrade package. The all stainless steel heat exchangers were custom built to meet the special requirements of the client, and were supplied complete with closed circuit water loop pumps.

The unique design offered by Lackeby provides many process and cost benefits when compared to traditional heat exchanger designs. Efficiency of digestion and hygenisation is enhanced, equilisation of the sludge temperature profile is improved, and unlike spiral heat exchangers, the innovative large sludge channel and open end turning chamber design minimises the risk of clogging.

To view further information on Lackeby Sludge Heat Exchangers please click here

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