Treatment of volcanic ash-contaminated surface waters through the optimisation of physical and chemical processes
J White, C Stewart, D Wareham, T Wilson.
GNS Science. GNS Science report 2011/35 30 p. SKU: SR_2011-035-pdf
Safe drinking-water, available to everyone, is a fundamental requirement for public health. A safe water supply is also essential for hygiene and sanitation. Volcanic activity can damage or disrupt water supplies in a number of ways. Experience from previous eruptions has shown that in general, for large municipal water treatment systems fed from surface waters such as lakes or reservoirs, the physical impacts of a volcanic ashfall will tend to overwhelm problems caused by chemical contamination resulting from the release of soluble components from the surface of the ash. A particularly important problem is that ash suspended in water increases the turbidity of the raw water supply. Turbidity is a critically important parameter for water treatment, and effective treatment depends on its control. The overall objective of the research described in this report was to investigate a physical (plain settling) and chemical (addition of coagulant) method for removing suspended ash from natural waters.