Greening of a water treatment plant

South Taranaki District Council is currently constructing a new water treatment plant to supply potable water to the Hawera urban area and some industrial and rural customers. The plant is a membranebased process with initial treated water capacity of 13,000m 3 /d and ultimate capacity of 19,000m 3 /d. To meet the Council's objectives of minimising operational and whole of life costs and being environmentally responsible, several innovative features were incorporated into the plant design, including:

• A heat pump utilising bore water as the heat source to heat water for membrane chemical cleaning solutions.
• Purchase of chemicals in forms that minimise the purchase costs, primarily by using forms that reduce freight costs.
• Modifications to plant hydraulics to maximise energy efficiency.
• A self-adjusting hydraulic flocculation baffle system which minimises energy use.
• Environmentally sustainable design features included in the amenity area design.

This "greening" approach to the plant design has resulted in an estimated reduction in oper ating costs in excess of $36,000/annum at the initial plant capacity in comparison to conventional approaches. The cost reductions implemented are all energy related - either directly by reduced electricity usage for pumping and heating, or indirectly in the case of reduced transportation costs.