THE INHIBITION OF METHANOGENIC ACTIVITY FROM ANAEROBIC DOMESTIC SLUDGES AS A SIMPLE TOXICITY BIOASSAY

A specific toxicity assay to detect heavy metal toxicity to the anaerobic digestion process was evaluated. The relative toxicity of metals, obtained by using the inhibition of methanogenic activity assay, was Zn>Cr>Cu>Cd>Ni>Pb. The sensitivity of this assay to metal toxicity was compared with four microbiological toxicity tests. In general, Microtox®, the Pseudomonas fluorescens growth inhibition (PFNEN) and the inhibition of methane production tests showed the highest sensitivity for the detection of metal toxicity from wastewaters and sludges.