Effect of granular activated carbon adsorption on mitigating microfiltration membrane fouling by algal organic matter

Abstract

Algal blooms can seriously affect the operation of water treatment processes including low-pressure (micro- and ultrafiltration) and high-pressure (nanofiltration and reverse osmosis) membranes mainly due to the accumulation of algae-derived organic matter (AOM). This study investigated the effect of granular activated carbon (GAC) pretreatment on PVDF microfiltration performance for the removal of AOM. Dissolved organic matter (DOM) solution of commercial humic acid, extra- and intracellular organic matter from two species of algae, and Cyanobacteria were used for the investigation of the fouling potential of the membrane. A comparison study of different DOM removal and fouling behaviors of microfiltration (MF) after GAC adsorption as pretreatment was evaluated under variable GAC dosage and solution pH. Almost 15–20% improvement in flux and decline in irreversible fouling occurred due to the pretreatment using 1.0 g/L of GAC for an hour. The intracellular material caused higher membrane fouling than humic acid due to the hydrophilic nature of the AOM. Membrane fouling and decline in flux increased with increasing pH in the range of 5.0–8.0. The comparison results might help to provide insights into the real challenge of dealing with the treatment of algal-laden water. HIGHLIGHTS Up to 72.23 and 85.95% of DOC and UV254 for CV-IOM can be removed by the GAC-MF process.; A greater flux decline and irreversible fouling were observed from AOM than HA.; Intermediate and standard blocking were the main fouling mechanisms for most DOMs.; IOM from each algae shows greater flux decline, and more irreversible fouling than EOM.;

Keywords

• activated carbon
• adsorption
• algal organic matter
• membrane fouling
• microfiltration