EFFECT OF ANAEROBIC STABILIZATION OF SEWAGE SLUDGES ON THE SURVIVAL OF ASCARIS-SUUM UNDER LABORATORY CONDITIONS

Survival of Ascaris suum eggs was studied during a laboratory anaerobi c stabilization of sewage sludges at a mesophilic and a thermophilic t emperatural range. The effect of a 20- and a 30-day sludge hydraulic r etention time (HRT) was also followed up with mesophilic stabilization . Mesophilic aerobic stabilization (36 degrees C) with the 20-day HRT showed the mean of 76.8% and with the 30-day HRT 76.2% of viable eggs, which is statistically not an important difference (P<0.01). The mean of 94% of viable eggs were detected in control after 30 days. Analysi s of the effect physico-chemical parameters of stabilization on the su rvival of eggs showed no dependence of the percentage of viable eggs i n fermenters with the 20-day HRT on pH and in fermenters with the 30-d ay HRT on pH and concentration of volatile fatty acids. Aerobic thermo philic stabilization (at 54 degrees C) reduced the viable nonembryonat ed eggs Ascaris suum from 82.4 to 9% in 10 min. After 10 min of stabil ization all eggs were eliminated.