Results of three semi-continuous anaerobic tests were reported and discussed. Each test was carried out by two parallel anaerobic reactors fed with waste activated sludge, either as it was sampled from the sewage treatment plant of Rome North or previously disintegrated by ultrasound treatment. Activated sludge was sonicated at the energy input of 5,000 or 2,500 kJ kg21 dry solids corresponding to a disintegration degree of approximately 8 or 4%, respectively. Sonication proved to be effective both in increasing VS destruction and cumulative biogas production. The best increase of VS destruction (from 30 to 35%) was achieved in test #3 carried out at high organic load (10 d residence time) and low energy input (2,500 kJ kg21 dry solids). The best increase in cumulative biogas production (from 472 to 640 NL after 67 d of tests i.e.) was obtained in test #1 at low organic load (20 d residence time) and high energy input (5,000 kJ kg21 dry solids). Specific biogas production varied in the tests carried out with untreated sludge (0.55 - 0.67Nm3 kg21 VS destroyed) but was practically unchanged for all the tests with sonicated sludge (0.7Nm3 kg21 VS destroyed).
IS SONICATION EFFECTIVE TO IMPROVE BIOGAS PRODUCTION AND SOLIDS REDUCTION IN EXCESS SLUDGE DIGESTION?
BRAGUGLIA CM;MININNI G;GIANICO A
2008
Abstract
Results of three semi-continuous anaerobic tests were reported and discussed. Each test was carried out by two parallel anaerobic reactors fed with waste activated sludge, either as it was sampled from the sewage treatment plant of Rome North or previously disintegrated by ultrasound treatment. Activated sludge was sonicated at the energy input of 5,000 or 2,500 kJ kg21 dry solids corresponding to a disintegration degree of approximately 8 or 4%, respectively. Sonication proved to be effective both in increasing VS destruction and cumulative biogas production. The best increase of VS destruction (from 30 to 35%) was achieved in test #3 carried out at high organic load (10 d residence time) and low energy input (2,500 kJ kg21 dry solids). The best increase in cumulative biogas production (from 472 to 640 NL after 67 d of tests i.e.) was obtained in test #1 at low organic load (20 d residence time) and high energy input (5,000 kJ kg21 dry solids). Specific biogas production varied in the tests carried out with untreated sludge (0.55 - 0.67Nm3 kg21 VS destroyed) but was practically unchanged for all the tests with sonicated sludge (0.7Nm3 kg21 VS destroyed).I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.