EFFECTS OF SUBSTITUENTS OF SOME AROMATIC COMPOUNDS AND PARTICULARLY OF ACID AZO DYES ON THE RESPIRATORY INHIBITION OF MICROBIAL POPULATIONS IN ACTIVATED SLUDGE

Abstract

The waste waters of industries that is drained in the municipal sewage plants bring often about the lowering of the purificatory ability because of the toxic properties for the microbes in the activated sludge. In order to elucide these toxic properties of the components in the waste water, the oxygen uptake rates of the microbes were measured in the media containing aromatic compounds such as anilines, phenols, naphtholsulphonic acids or acid azo dyes, and thereby the effects of the substituents of these compounds on the respiratory inhibition were investigated. The results are as follows. All of the compounds used are inhibitory to the respiration of the microbes in the activated sludge. The introduction of some substituents e. g. -CH₃, -NO₂, -SO₃H, -COOH etc. to the compounds or the replacement of the benzene ring by the naphthalene ring weakens the inhibition, while the introduction of -Cl or -Br strengthens it.