Abstract
The anaerobic fate of six tetraalkylammoniums (TAAs) of the general formula R4N+Br- (R = C1∼6) and with different alkyl chain lengths were investigated with laboratory-scale equipment. The results showed that tetramethylammonium, tetraethylammonium, tetra-n-propylammonium and tetra-n-butylammonium were degraded at different levels by anaerobic bacteria, but that tetra-n-pentylammonium and tetra-n-hexylammonium were difficult to degrade and had acute toxicity to biogas production at concentrations of over 50 mgC · l-1. TAA showed increasing inhibitory activity to the metabolism of glucose with an increase in alkyl chain length under anaerobic condition. A complete bioactivity recovery of anaerobic sludge inhibited by five TAA (C1∼5) could be achieved in two months. Nevertheless, the toxicity of tetra-n-hexylammonium to anaerobic microorganisms was irreversible, which was considered a substance highly hazardous to anaerobic microorganisms, particularly, methanogens.
