In late 2015 Queenstown Lakes District Council (QLDC) commissioned Veolia to trial the ACTIFLO® process at Beacon Point Intake, which is one of two intakes on Lake Wanaka for the Wanaka drinking water supply. Since 2008 the supply has been experiencing increasing amounts of algae being drawn from the intake into the water supply.
Actiflo is a compact high rate clarification system developed and patented by Veolia that utilises micro-sand enhanced flocculation (MEF) in conjunction with lamella settlers. The micro-sand particles provide a large surface area and act as a seed for floc formation, whilst also providing ballast which increases the settling velocity of these particles. Whilst this treatment system has been employed at a wide variety of reference sites worldwide, most of these sites experience a turbidity of > 500 NTU. This paper specifically highlights the success of the technology in removing algae in Lake Wanaka’s low turbidity water.
A completely self-contained Veolia pilot system was used for simulating the operating conditions of a full scale Actiflo installation. The primary purpose of the trial exercise for QLDC was to determine the suitability of the Actiflo treatment process for full scale reduction in the amount of algae drawn into the drinking water supply.
A successful demonstration of Actiflo feasibility was proven during the trial.