| Affiliation: | (1) Division of Environmental & Geosystem Engineering, Inha University, 253 Yong Hyun Dong, Nam Gu, 402-751 Incheon, Korea;(2) Department of Environmentals, Cheonan National Technical College, 330-717 Cheonan, Korea |
| Abstract: | Zeolite added activated sludge unit (ZU) under anoxic conditions improved nitrate removal efficiency by 48% (i.e., equivalent to approximately 10 mg//) greater than that of a conventional activated sludge unit (CU) regardless of varying C/N ratio ranging from 0 to 4.8. For a C/N ratio of 4, no significant differences of denitrification rate were found between two units showing a range of 6.7 to 6.9 mg NO 3 - -N/g VSS (volatile suspended solids) hr. However, a C/N ratio decrease to 1.6 was ascribed to considerable differences in denitrification rate showing 4.15 mg NO 3 - -N/g VSS ·hr for the ZU, which was 39% greater than that of the CU presenting at 2.98 mg NO 3 - -N/g VSS ·hr. It was decided that the presence of greater concentration of MLVSS (mixed liquor suspended solids) in the ZU can be efficiently used for enhanced denitrification as a potential carbon source due to autolysis, although a lower concentration of COD (i.e., less than 1.6 of C/N ratio) is introduced. |
