T281 Arsenic, Manganese, Chromium, and Other Geogenic Contaminants, Including Radionuclides in Hydrological Systems—Source, Biogeochemical Cycling, Toxicity, and Removal II

Wednesday, 7 November 2018
1:30 PM - 5:30 PM
Room 133

EFFECT OF CALCIUM AND BICARBONATE ON IRON REMOVAL DURING GROUNDWATER TREATMENT

Paper number: T281-5
Program: Technical Sessions
Time: 2:20 PM – 2:40 PM

Authors

Abstract

Groundwater is the main source of drinking water in the North-Brabant Province of the Netherlands. Brabant Water, the public water supply company of the region, pumps 200 million cubic meter of the raw groundwater from a depth between 25-300 meter. The groundwater is treated in 32 plants and supplied to a population of 2.5 million across the province.

Water treatment plant Eindhoven is the largest groundwater water treatment plant of Brabant Water, producing 25 Mm3/year drinking water. The produced drinking water is of high quality. The current treatment scheme comprises tower aeration, pre-rapid sand filtration, lime and potassium permanganate dosing in pre-filtrate and post-rapid sand filtration. In 2018 the treatment facility will have to be renovated and currently the process technology department of Brabant Water is investigating options to optimize the treatment design.

This talk is focused on the influence of calcium and bicarbonate on the filterability of iron particles during rapid sand filtration. Pilot tests at Water Treatment Plant Eindhoven show that dosing calcium and bicarbonate can improve iron removal during rapid sand filtration. Higher concentrations of these ions in raw water may lead to better removal of iron in rapid sand filters. These new insights gave process technologists an extra dimension to look at iron removal. It was already very helpful in optimizing iron removal / lowering turbidity at several groundwater treatment plants of Brabant Water. The specific role of Ca and HCO3 during Fe removal in classic rapid sand filtration need to be studied further to gain mechanistic insights.

Based on the findings, an alternative treatment scheme for water treatment plant Eindhoven has been proposed. The alternative scheme includes caustic soda (NaOH) dosing in the raw water to raise the HCO3 concentration, tower aeration and single step rapid sand filtration. The alternative treatment scheme at Eindhoven is expected to reduce chemical use and maintenance costs besides improving water quality.

Geological Society of America Abstracts with Programs. Vol. 50, No. 6

doi: 10.1130/abs/2018AM-321113

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