APPLICABILITY OF FIXED BED BIOFILM REACTOR FOR NITROGEN REMOVAL FROM SEWAGE WITH HIGH NITROGEN CONTENTS

Lee, Hae-Goon; Choi, Myung-Won; Wang, Sung-Hwan; Park, Tae-Joo; Kim, Chang-Won

Environmental Engineering Research 2001;6(2): 55-61.

Hae-Goon Lee^†, Myung-Won Choi, Sung-Hwan Wang, Tae-Joo Park, and Chang-Won Kim

Department of Environmental Engineering, Pusan National University, Pusan 609-735, Korea

Corresponding Author: Hae-Goon Lee ,Tel: 182-51-583-5351, Fax: +82-51-583-5350, Email: poseidon@hyowon.pusan.ac.kr

Received: December 9, 2000; Accepted: March 10, 2001.

ABSTRACT

The objective of this investigation was to evaluate applicability of a fixed bed biofilm reactor for removing nitrogen from sewage mixed with various industrial wastewater and to assure design data for retrofitting Changlim sewage treatment plant, Pusan, Korea. The influent total nitrogen concentration of the plant was relatively high, up to 120 mg/L with an average of 60 mg/L in 1998, whereas the influent BODs concentration was very low, an average of 70 mg/L. The fixed bed biofilm reactor was 11.2 m₃ pilot scale and consisted of anaerobic-anoxic-aerobic zone with bar-type fixed bed inserted. The forty-percent of the influent was directly fed to the anoxic zone for effective denitrification. Two overall hydraulic retention times (7.6 hrs and 10 hrs) were tested under various loading rates and temperature conditions. Sufficient amount of alkalinity and organic matter were added for proper nitrification and denitrification. The removal efficiencies of BOD5 and COD were 87% and 77% under highest organic loading rate of 0.95 kgCOD/m₃ • d, respectively. At HRT of 7.6 hrs, the nitrification efficiency was maintained over 92% until the loading rate reached up to 0.13 kgN/m₃ • d and then the nitrification rate and efficiency were gradually decreased. But at HRT of 10 hrs, the nitrification efficiency was maintained over 95% up to applied loading rate of 0.28 kgN/m3 • d. The denitrification efficiencies were more than 80% in both HRT conditions. The temperature correction factors for nitrification were 8N = 1.08(10~20°C) and BN = 1.02(20 — 25 °C). For denitrification, 8DN was 1.05 at the 20~25°C. Under given influent conditions, the overall HRT of 10 hrs was sufficient to satisfy effluent quality criteria until the temperature reaches 15°C.