THE MONITORING OF AEROBIC FLOC-LIKE
SLUDGE INFLUENCED BY CALCIUM IONS

Yoon, Young H.; Park, Jae Ro; Kim, In S.

doi:2006.11.3.127

Environmental Engineering Research 2006;11(3): 127-133. DOI: https://doi.org/10.4491/eer.2006.11.3.127

THE MONITORING OF AEROBIC FLOC-LIKE SLUDGE INFLUENCED BY CALCIUM IONS

Young H. Yoon¹, Jae Ro Park¹, and In S. Kim²^†

¹'Construction and Environment research division, Korea Institute of Construction Technology, Daehwa-dong, Goyang, Gyeonggi 411-712, Korea
²Dept. of Environ. Sci. & Eng., Gwangju Institute of Science and Technology (GIST), 1 Oryong-dong, Buk-gu, Gwangju 500-712, Korea

Corresponding Author: In S. Kim ,Tel: +82-62-970-2436 , Fax: +82-62-970-2434, Email: iskim@gist.ac.kr

Received: January 7, 2006; Accepted: March 9, 2006.

ABSTRACT

Aerobic floc-like sludge was formed in a batch reactor and the effect of cations on the formation of aerobic floc-like sludge was studied. In order to enhance the formation (rate) of aerobic floc-like sludge, cations such as KT, Na+, Ca2+, and Mg2+ were added to the seed sludge. It was found that Ca2+ had positive effect on the formation of floc-like sludge, as measured by sludge volume index (SVI) for settle ability. The formation of floc-like sludge was confirmed by the microscopic observation after DAPI staining. The scattered forms of sludge samples at the initial stage became aggregated to form floes after Ca"T addition. To ensure the functions of sludge floes in a treatment plant, the gradient of ionic species around the surfaces of floc-like sludge was monitored by ion selective microelectrodes for NH4 , NO3", and pH. The effective concentration of Ca2+ ion to form floc-like sludge was determined to be 750 mg/L (0.15 mg Ca27mg MLSS). Under the effective Ca2+ condition, the SVI value was the lowest and large distribution of nitrifying bacteria at the outer surface was observed in the aerobic floc-like sludge. From the results, it was found that the calcium ion functioned as an agent for the formation of aerobic floc-like sludge, resulting in the enhanced nitrification.

Keywords: Aerobic floc-like sludge | Calcium ion | Ion-selective microelectrodes (ISEs) | Sludge volume index(SVI)