Changes in the ecological properties of organic wastes during their biological treatment

It was revealed, that in the process of anaerobic pretreatment for 15 days, the toxicity increased by a mean of 1.3-, 1.9- and 1.1-fold for OFMSW, SS and OFMSW + SS, respectively. During composting, the toxicity level of these pretreated samples decreased more rapidly as compared with those which were not pretreated. As a result, the toxicity levels of the elutriates from the final composts made of pretreated wastes OFMSW, SS and OFMSW + SS were three-, two- and 17-fold lower for D. magna and 15-, 21- and 12-fold lower for P. caudatum. As follows from phytotoxicity estimations, composts from digested substrates became mature on the 60th day and had a stimulation effect on the plants after the 90th day of incubation. For the composts prepared from raw substrates, a significantly longer period was needed for maturation. On the basis of ecotoxicity changes of the wastes treated, it can be concluded that anaerobic pretreatment of the municipal solid wastes is an effective acceleration tool for further composting and that waste mixtures can be treated more efficient as compared with raw wastes.