Denitrification and biofilm growth in a pilot-scale biofilter packed with suspended carriers for biological nitrogen removal from secondary effluent

• Published in: Journal of environmental sciences (China) Vol. 32; no. 6; pp. 35 - 41
• Main Authors: Shi, Yunhong, Wu, Guangxue, Wei, Nan, Hu, Hongying
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.06.2015
• Subjects: Biofilm; Biofilms - growth & development; Biokinetics; Biological Oxygen Demand Analysis; Biomass; Bioreactors - microbiology; Denitrification; Equipment Design; Ethanol - chemistry; Filtration - instrumentation; Filtration - methods; Nitrogen - isolation & purification; Pilot Projects; Pilot-scale biofilter; Quartz - chemistry; Suspended carriers; Tertiary denitrification; Water Pollutants, Chemical - isolation & purification; Water Purification - instrumentation; Water Purification - methods; 中试; 填料; 悬浮载体; 污水; 生物滤池; 生物脱氮; 生物膜; 生长动力学; Tertiary denitrification; Biofilm; Pilot-scale biofilter; Biokinetics; Suspended carriers
• ISSN: 1001-0742; 1878-7320
• DOI: 10.1016/j.jes.2014.12.012

Tertiary denitrification is an effective method for nitrogen removal from wastewater. A pilot-scale biofilter packed with suspended carriers was operated for tertiary denitrification with ethanol as the organic carbon source. Long-term performance, biokinetics of denitrification and biofilm growth were evaluated under filtration velocities of 6, 10 and 14 m/hr. The pilot-scale biofilter removed nitrate from the secondary effluent effectively, and the nitrate nitrogen（NO_3-N） removal percentage was 82%, 78% and 55% at the filtration velocities of 6, 10 and 14 m/hr, respectively. At the filtration velocities of 6 and 10 m/hr, the nitrate removal loading rate increased with increasing influent nitrate loading rates, while at the filtration velocity of 14 m/hr, the removal loading rate and the influent loading rate were uncorrelated.During denitrification, the ratio of consumed chemical oxygen demand to removed NO_3-N was 3.99-4.52 mg/mg. Under the filtration velocities of 6, 10 and 14 m/hr, the maximum denitrification rate was 3.12, 4.86 and 4.42 g N/（m^2·day）, the half-saturation constant was 2.61, 1.05 and 1.17 mg/L, and the half-order coefficient was 0.22, 0.32 and 0.24（mg/L）1/2/min,respectively. The biofilm biomass increased with increasing filtration velocity and was 2845,5124 and 7324 mg VSS/m^2 at filtration velocities of 6, 10 and 14 m/hr, respectively. The highest biofilm density was 44 mg/cm~3 at the filtration velocity of 14 m/hr. Due to the low influent loading rate, biofilm biomass and thickness were lowest at the filtration velocity of 6 m/hr.