Desalination of Borneo tropical brackish peat water with adsorption process in continuous electrocoagulation treatment

Abstract

Borneo tropical brackish peat water is originated from the decomposed living materials in peatland areas. The water source is naturally formed as resulted by the intrusion between peat water and sea water at the river delta during high tide. In Sarawak, Malaysia, brackish peat water is available in the coastal rural areas in which some of these areas are associated with water supply shortage. Recent studies report that electrocoagulation treatment is effective in reducing total organic content from peat water sources. However, the application of such treatment to reduce salinity levels in brackish peat water is yet to be investigated. As such, this study aims to investigate the feasibility of continuous electrocoagulation treatment to reduce salinity levels in Borneo tropical brackish peat water with adsorption process. Correspondingly, the objectives of this study are (i) to conduct an experimental study to reduce salinity levels in brackish peat water by using continuous electrocoagulation treatment with aluminium electrodes, (ii) to develop adsorption theorem and kinetic models to determine the salinity adsorption capacity and constant rate of salinity reduction in brackish peat water respectively, and (iii) to identify the salts elements on the produced flocs with Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray (EDX). This study reports the highest salinity reduction efficiency for brackish peat water with an initial salinity level of 0.50%. At an initial salinity level of 0.50%, the salinity level has reduced from 4507 mg/L to 527 mg/L with 88.3062% of salinity reduction efficiency. According to Freundlich adsorption theorem, the salinity reduction in brackish peat water is possibly due to multilayer adsorption in continous electrocoagulation treatment. Additionally, the salinity reduction in brackish peat water follows the non-linear pseudo-first-order model at constant rate of 2.62 min−1. Lastly, the SEM and EDX analysis have revealed the presence of salts elements which are calcium, silica, sulphate, chloride, magnesium, and sodium on the produced flocs. The presence of salts elements on the produced flocs signify adsorption process is the precursor to the salinity reduction in brackish peat water. Overall, continuous electrocoagulation treatment which produces aluminium hydroxides is feasible to reduce salinity levels in Borneo tropical brackish peat water with adsorption process.