Removal of molluscicide compound: A comparison of metaldehyde removal performance between rubber-based aerobic granules and molasses-based aerobic granules

Abstract

Rubber-based aerobic granules (RAGS) were developed in a bioreactor. Outside of the bioreactor, RAGS were supplemented with molasses wastewater to produce molasses-based aerobic granules (MAGS). Rates of RAGS and MAGS elimination and growth were calculated across a range of 180–330 mg/L of metaldehyde. Metaldehyde removal rates for RAGS and MAGS were 84 % and 85 %, correspondingly. Rates of biodegradation (K1) ranged from 0.402 to 0.063 h−1 for RAGS and from 0.404 to 0.065 h−1 for MAGS. There was a negative correlation between metaldehyde concentration and the first-order rate constant. MAGS had somewhat higher metaldehyde removal capacities than RAGS, with a lower Ks value (234 mg/L) than RAGS (282 mg/L). The MAGS had a higher μmax (0.188 day−1) value than the RAGS (0.129 day−1). RAGS and MAGS show promise for use in aerobic granular sludge remedy of wastewater due to their ability to degrade metaldehyde.