| EVALUATION OF IN-SITU EXTERNAL CARBON SOURCES FOR HIGH PERFORMANCE OF DENITRIFICATION IN GRAIN DISTILLERY WASTEWATER TREATMENT PLANT |
| Sun-Jip Kim† |
| G&G EnviTech Co., Ltd, Doosan bldg. 6th FL., 39-3 Sungbok-dong, Yongin, Kyunggi-do 449-795, Korea |
Corresponding Author:
Sun-Jip Kim ,Tel: +82-31-260-6092, Fax: +82-31-266-7640, Email: sunjipkim@yahoo.co.kr
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Received: June 12, 2004; Accepted: December 10, 2004. |
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| ABSTRACT |
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The influent organic carbon-to-nitrogen (C/N) ratio of 0.45-3.27 g BODs/g TKN for the extended aeration process at the grain distillery wastewater treatment plant in P distillery company was lower than the theoretical value of 3.71 g BOD.Vg TKN for successful denitrification due to anaerobic pre-treatment when it is considered to be retrofitted to biological nutrient removal system. The impure alcohol produced during the alcohol distillation as a by-product and the raw wastewater decanted with centrifugal decanter (CDE) were evaluated as in-situ external carbon sources for successful denitrification. The high specific denitrification rates (KD) of 254 mgN/gVSS/day and 215 mgN/gVSS/day were observed when the impure alcohol and the CDE characterized as high content of organics and low content of nitrogen were used as external carbon sources. Although higher specific denitrifiation rate for the impure alcohol was achieved, the production rate of the impure alcohol is 0.33-0.67 L/m3 based on the grain distillery wastewater which is short for high performance of nitrogen removal. The CDE was designed to use as a main external carbon source while the impure alcohol was designed to use for flushing of residual oxidized nitrogen. After investigation of denitrification rate equivalent to the CDE dosing by respirometry, the optimum C/N ratio for the CDE was 3.0-4.5 g BOD5/g NOj-N. The Bardcnpho (4 stage) system was operated with dosing of the CDE and the impure alcohol in the pre-anoxic chamber and the post-anoxic chamber with the dosing rates of 5.7% (v/v) of the CDE based on influent flowrate (1,427 mg BOD5/L influent/day) and 0.025% (v/v) of the impure alcohol based on influent flowrate (157.5 mg BOD5/L influent/day). After dosing of the CDE in influent, the BOD5/TKN ratio was increased from 2.55 to 4.10. High denitrification efficiency of 90.1% was achieved with maintenance of high BOD5 removal efficiency of 99.4%. |
| Keywords:
external carbon source | denitrification | nitrogen removal | C/N ratio | grain distillery wastewater |
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