Water Science & Technology Vol 55 No 1-2 pp 203–208 © IWA Publishing 2007 doi:10.2166/wst.2007.053
Relationship between the electric conductivity and phosphorus concentration variations in an enhanced biological nutrient removal process
Kwang-Soo Kim*, Ji-Seon Yoo*, Sungyoun Kim*, Hee Ja Lee*, Kwang-Ho Ahn* and In S. Kim**
*Construction Environment Research Dept., Korea Institute of Construction Technology (KICT) 2311 Daehwa-dong, Ilsanseo-gu, Goyang-si, Gyeonggi-do, 411-712, Korea (E-mail: kskim@kict.re.kr)
**Dept. of Env. Sci. and Eng., Gwangju Institute of Science and Technology (GIST) 1 Oryong-dong, Buk-gu, Gwangju, 500-712, Korea
ABSTRACT
Phosphorus release and uptake in a sequencing batch reactor were monitored by the simple on-line measurements of electric conductivity (EC) and oxidation-reduction potential (ORP), and the result was verified by the measurement of phosphate concentration changes. The influence of nitrate ion presence on the phosphorus removal was evaluated by a jar test operated in the cyclic anaerobic (anoxic)–aerobic condition. The relationships of EC, ORP and metal species with phosphorus concentrations were investigated. Under strict anaerobic conditions, EC showed positive correlation with phosphorus concentrations, but it became negligible under anoxic conditions with nitrate present. Strong inverse correlation was found between ORP values and phosphorus concentration. The increase and decrease of magnesium and potassium ions took place in accordance with phosphorus release and uptake, and the relationship between the metal species and phosphorus changes was clearer in the anaerobic condition than anoxic condition.
Keywords: Electric conductivity; metal species; ORP; phosphorus; sequencing batch reactor
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