EFFECTS OF AN ORGANOTIN PVC STABILISER ON ANOXIC DEGRADATION OF ORGANIC MATTER / Effekter av en tennorganisk PVC stabilisator på den syrefria nedbrytningen av organiskt material

Many organotin compounds are toxic, thus their occurrence in the environment is of considerable concern, and several of these substances are regarded as priority pollutants that require further investigation. Organotins are used primarily as heat stabilisers in PVC plastic, and they are therefore found in landfills in which discarded PVC products have been deposited. In an earlier study, it was found that a widely used methyl tin PVC stabi-liser inhibited microbial generation of CH4 during anoxic degradation, and the objective of the present study was to elucidate possible mechanisms of such inhibition. CH4 and fermentation products were measured continuously for a period or 219 days in waste material amended with a methyl tin stabiliser. The results show that CH4 formation was retarded for 84-198 days during fermentation of the waste material. Furthermore, it seemed that not only the methyl tins, but also their sulphur organic ligands, play an important role in retarding the formation of CH4,. The methyl tin stabiliser apparently affected both the fermentative organisms that provided the substrate for the methanogens, as well as the methanogens.