Nitrification-denitrification and activated sludge settlement
(EN)
Andreadakis, AD
(EN)
Bench scale activated sludge units, fed with sewage from the main sewer of Athens, were used to study the biological removal of nitrogen. Nitrification and denitrification rates for different solids retention times, temperatures and carbon to nitrogen ratios were measured. A solids retention time of eight days was found to be adequate for complete nitrification throughout the year. Sludge settling characteristics, in terms of dilute sludge volume index, DSVI, were correlated to the concentrations of nitrates in the effluent. Due to the lower concentration of nitrates, the denitrifying activated sludge had better settling characteristics. Zone settling velocity measurements were used to determine values for the constants incorporated in the flux theory. Application of this theory indicated that a substantial reduction of the area of the final clarifier may be realized with a nitrification-denitrification system.
(EN)
