LAquatic Natural Organic Matter (NOM) Removal in Biological Filters

摘要

The aim of this work was to study the biodegradability of aquatic natural organic matter (NOM) through measurements of the biodegradable dissolved organic carbon (BDOC) in several water samples. Two different bioassays were used to determine BDOC; theBillen-Servais method (inoculum: raw water) and the Joret-Levi method (inoculum: acclimated sand) and three different types of water were studied in this work: a natural water from the IJzquiza Reservoir (Burgos, Spain), a synthetic water prepared usingnatural fulvic acids extracted from the IJzquiza Reservoir and a synthetic water prepared using a commercially suppliedhumic acid. The natural water from the Uzquiza Reservoir (Burgos, Spain) showed the most biodegradable NOM whereas the solutions of pure humic substances had a low biodegradability, showing values slightly higher the fulvic acids. The Billen-Servais method (inoculum: raw water) gave substantially lower BDOC values than the Joret-Levi method (inoculum: acclimated sand) for the three types of NOM studied. Additionally, several filtration tests were performed using columns filled with either sand (a non-adsorbing media) or granular activated carbon: GAC (an adsorbing media), including two operating conditions: sterile filtration and biologically active filtration. GAC filters showed a substantially greater TOC removal than sand filters, due to the high adsorptive capacity of GAC for humic substances; biologically active filters showed a slightly greater efficiency (about 3%) than sterile filters, which was similar regardless of the type of filter used (GAC or sand).