Arsenic removal from drinking water using treated laterite-based adsorbent

Abstract

Access to safe drinking water is an essential element for sustainable life. Arsenic poisoning in groundwater has been a cause of concern since decades and is one of the most hazardous contaminants of potable groundwater. The major sources of contamination are geogenic, agricultural, and industrial as well. This chapter presents the development of a novel adsorbent using naturally occurring laterite soil that has proved to be an excellent material for the removal of arsenic from groundwater. Natural laterite has been acid-activated using acid alkali treatment process under optimized process conditions to prepare treated laterite (TL) having 40 times higher adsorption capacity compared to the untreated material. The enhanced adsorption capacity of 8 mg/g for As(III) and 24.1 mg/g for As(V) is the highest among all natural adsorbents or their derivatives reported so far and also has the advantage of a granular nature that rules out high-pressure drop during operation. The adsorbent also meets the safe disposal guidelines and can even be used for road laying purpose without any risk of leaching. The laboratory-scale column run experiments are carried out to study the effect of incoming concentration, flow rate, bed height, and the presence of co-ions. The adsorption equilibrium and kinetics using TL as an adsorbent are studied in detail, and a kinetic model has been established. The model parameters required for upscaling are determined by comparing with the experimental results. Different aspects of scale-up of the technology in the form of integrated filters designed for domestic applications (capacity 100 L/day) as well as community-scale filters (capacity 2 m³/h) are discussed in brief. A transport-based model to predict the permeate concentration and filter life is also presented in detail that can be of immense help at different stages of product life, including design, installation, and maintenance.