CleanStream NZ has completed several dredging and dewatering projects for local government bodies nationwide. Utilising light and mobile amphibious dredges with modern dewatering equipment, site set-ups are fast and efficient, reducing cost and complexity. This results in efficient silt/sludge removal with a low environmental footprint – dry solids results are second to none.
Accurate polymer dosing is crucial to optimising the solids removal process and minimising environmental impact. However, due to the rapidly changing solids concentration during dredging, this is impossible to do with manual grab sampling. Applied Instruments was engaged to investigate ways to further improve the existing process.
By integrating a Berthold microwave-based solids meter with a Badger Meter mag flow meter, the Applied team designed and commissioned a highly accurate, fast response way to fine tune the polymer dosing. The solids concentration data is fed into a controller along with the flow rate, allowing a total solids rate to be calculated. The Berthold is loaded with empirically derived data of mass flow rate against polymer dose, and the appropriate output flow rate can be sent to the polymer dosing pump in milliseconds. The result: consistently clean filtrate, and a huge increase in retained solids.