The presence of worms in aerobic wastewater treatment may lead to a substantial sludge reduction, but the practical application of worms for sludge reduction is uncontrollable because of unstable worm growth. We have tested the survival and reproductive activity of schizogenetic clones of Aeolosoma hemprichi and Aeolosoma viride in cultures where the medium was made of activated sludge from a wastewater treatment plant. We were able to maintain the survival of worms in cultures for more than three months, using activated sludge from the oxidation stage of the wastewater treatment plant as a medium. The reproductive activity of the worms decreased in the cultures maintained on sludge compared to control cultures; the number of filial zooids per day was reduced to 34% in Aeolosoma hemprichi and to 30% in Aeolosoma viride. The effect of the worms on volumetric sludge reduction was assessed in small-scale experiments with a minimal concentration of 7 worms per ml. Sludge reduction increased during the first three days and reached approximately 11-12%. Higher concentrations of worms (20, 35 worms per ml) produced similar effects of sludge volumetric reduction. A cyclical process model of volumetric reduction of sludge in the presence of effective densities of worms was tested; in each cycle the effective density of worms was obtained using part of the sludge from the previous cycle to prompt the reproduction of worms and the process of volumetric reduction in new sludge. The first test, which lasted fifteen days and involved 4 cycles, gave a general volumetric reduction of 22% in the sludge treated with Aeolosoma hemprichi and 29% of that treated with Aeolosoma viride. The second test, lasting 60 days and involving 15 cycles, produced a volumetric reduction of 27% of the sludge treated with Aeolosoma hemprichi and 31% of that treated with Aeolosoma viride. A hypothetical model built on the basis of the experimental results foresees on an annual basis 121 cycles and an overall volumetric reduction of 25% of the sludge treated with Aeolosoma hemprichi and 45% of that treated with Aeolosoma viride.
Reduction rates and growth of two species of Aeolosomatidae on activated sludge / Falconi R.; Cristiani E.; Tomba G.; Zaccanti F. - In: SHUISHENG SHENGWU XUEBAO. - ISSN 1000-3207. - STAMPA. - 31:(2007), pp. 166-171. (Intervento presentato al convegno 10 ISAO 2006 - The Thenth International Symposium on Aquatic Oligochaeta tenutosi a Wuhan China nel 16-21 OTTOBRE 2006).
Reduction rates and growth of two species of Aeolosomatidae on activated sludge.
FALCONI, ROSANNA;ZACCANTI, FRANCESCO
2007
Abstract
The presence of worms in aerobic wastewater treatment may lead to a substantial sludge reduction, but the practical application of worms for sludge reduction is uncontrollable because of unstable worm growth. We have tested the survival and reproductive activity of schizogenetic clones of Aeolosoma hemprichi and Aeolosoma viride in cultures where the medium was made of activated sludge from a wastewater treatment plant. We were able to maintain the survival of worms in cultures for more than three months, using activated sludge from the oxidation stage of the wastewater treatment plant as a medium. The reproductive activity of the worms decreased in the cultures maintained on sludge compared to control cultures; the number of filial zooids per day was reduced to 34% in Aeolosoma hemprichi and to 30% in Aeolosoma viride. The effect of the worms on volumetric sludge reduction was assessed in small-scale experiments with a minimal concentration of 7 worms per ml. Sludge reduction increased during the first three days and reached approximately 11-12%. Higher concentrations of worms (20, 35 worms per ml) produced similar effects of sludge volumetric reduction. A cyclical process model of volumetric reduction of sludge in the presence of effective densities of worms was tested; in each cycle the effective density of worms was obtained using part of the sludge from the previous cycle to prompt the reproduction of worms and the process of volumetric reduction in new sludge. The first test, which lasted fifteen days and involved 4 cycles, gave a general volumetric reduction of 22% in the sludge treated with Aeolosoma hemprichi and 29% of that treated with Aeolosoma viride. The second test, lasting 60 days and involving 15 cycles, produced a volumetric reduction of 27% of the sludge treated with Aeolosoma hemprichi and 31% of that treated with Aeolosoma viride. A hypothetical model built on the basis of the experimental results foresees on an annual basis 121 cycles and an overall volumetric reduction of 25% of the sludge treated with Aeolosoma hemprichi and 45% of that treated with Aeolosoma viride.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
