EFFECTS OF DETERGENT ZEOLITE IN A NITROGEN REMOVAL ACTIVATED SLUDGE PROCESS

摘要

Two detergent zeolites, Doucil-P and Doucil-A24, were tested for their weighting effect in batch tests and on a nitrogen removal activated sludge process. The batch tests with a long contact time revealed a negative effect of zeolite on sludge filterability. In continuous pilot tests, the zeolite accumulated in sludge causing an increase in sludge suspended solids of up to 25 to 30%. This accumulation improved the activated sludge settling characteristics. The zeolite did not affect the treatment efficiency or the amount of filamentous bacteria. Measurements were made on sludge surface characteristics, i.e. specific surface area, surface potential and surface energy. A slight increase in surface area and decrease in negative surface charge caused by zeolite addition was observed. The aluminium concentrations in sludge increased but there was no correlation to the concentration of the accumulated zeolite in sludge.