Embedding Fe(0) electrocoagulation in a biologically active As(III) oxidising filter bed

Long-term consumption of groundwater containing elevated levels of arsenic (As) can have severe health consequences, including cancer. To effectively remove As, conventional treatment technologies require expensive chemical oxidants to oxidise neutral arsenite (As(III)) in groundwater to negatively charged arsenate (As(V)), which is more...

As(III) removal in rapid filters: Effect of pH, Fe(II)/Fe(III), filtration velocity and media size

In the top layer of aerated rapid sand filtration systems, uncharged As(III) is biologically converted to charged As(V). Subsequently, the main removal mechanism for As(V) is adsorption onto oxidised, flocculated Fe(III) (hydrous ferric hydroxides; HFO). The aim of this research was to understand the interactions between As and Fe in...

Arsenic removal in rapid sand filters

Arsenic (As) mobility in water is worldwide studied since its toxicity was proven in 1888. Intake of As can lead to skin disease, cancer, kidney and heart failure, diabetes and paralysis. In the Netherlands, groundwater used for drinking water production contains As in the range from 0 – 70 μg/L. Currently, all groundwater treatment plants...

Biological As(III) oxidation in rapid sand filters

The objective of this study was to investigate whether arsenic-oxidising bacteria (AsOB) will grow and survive in rapid sand filters. Additionally, the interdependence of other groundwater constituents (Fe(II), Mn(II), NH₄) with biological As(III) oxidation was investigated. For this purpose As(III) oxidation was monitored in pilot...

Effect of supernatant water level on As removal in biological rapid sand filters

Current groundwater treatment facilities, mostly relying on aeration-filtration configurations, aim at the removal of iron (Fe), ammonia (NH ₄ ⁺ ) and manganese (Mn). However, recently water companies expressed the ambition to also reduce arsenic (As) concentrations in these rapid sand filters. The aim of this study was...

As(III) oxidation by MnO₂ during groundwater treatment

The top layer of natural rapid sand filtration was found to effectively oxidise arsenite (As(III)) in groundwater treatment. However, the oxidation pathway has not yet been identified. The aim of this study was to investigate whether naturally formed manganese oxide (MnO₂), present on filter grains, could abiotically be responsible...