Evaluation of laterite as filter media to remove arsenic from groundwater
Arsenic (As) in drinking water has a chronic effect on humans and thus is a global health issue. Mostly people of Pakistan use groundwater for drinking, consequently prone to As toxicity. The objective of this study was to evaluate laterite as an adsorbent media for As removal, and subsequent preparation of a low-cost As filter. Laterite was tested for As adsorption capacity through batch sorption experiment and fitting Langmuir model. Two identical filters were prepared using a variable particle size of laterite and substrate material ratios (sand, activated carbon, and brick chips). Arsenic contaminated water was poured daily and collected at the bottom for analysis. The water samples were analyzed for As using an atomic absorption spectrophotometer coupled with hydride generation assembly. Other water quality parameters viz., electrical conductivity (EC), pH, chloride (Cl), total suspended solids (TSS), total dissolved salts (TDS), nitrate (NO-3), calcium (Ca), magnesium (Mg), sodium (Na), potassium (K), carbonate (CO-3), bicarbonate (HCO-3), and sulfate (SO-4) were also tested. Filter1 had an As removal efficiency of about 83 to 93 % while Filter 2 had about 67 to 85 %. Most of the water quality parameters remained under the WHO recommended limits indicating no harmful addition to the filtered water by substrates. It appears that laterite may serve as an economical option for As removal from contaminated groundwater.