title: Removal of nitrogen and phosphorus from the secondary effluent in tertiary denitrifying biofilters combined with micro-coagulation.
abstract: Effective control of nitrogen and phosphorus in secondary effluent can reduce or avoid the eutrophication of receiving water bodies. Two denitrifying biofilters (DNBFs) packed with different sizes of quartz sands combined with micro-coagulation were operated for simultaneous removal of nitrogen and phosphorus from the secondary effluent. The quartz sand size in one DNBF was 2-4 mm (DNBFS), and in the other was 4-6 mm (DNBFL). In both DNBFs, methanol was used as the electron donor and different organic carbon to nitrogen (C/N) ratios were applied. Under C/N ratios of 1.5, 1.25, and 0.75 g/g, the nitrate nitrogen (NO3(-)-N) removal percentages were 73%, 77%, and 50% in DNBFS, and 43%, 25%, and 21% in DNBFL; the effluent total phosphorus concentrations were 0.15, 0.14, and 0.18 mg/L in DNBFS, and 0.29, 0.35, and 0.24 mg/L in DNBFL. The performance of both biofilters was quite stable within a backwashing cycle. The NO3(-)-N reduction rates were 1.31, 1.10, and 0.48 mg/(L·min) in DNBFS, and 0.97, 0.27, and 0.10 mg/(L·min) in DNBFL. For biomass detached from both biofilters, their denitrifying activities were similar. Biofilm biomass in DNBFS was higher than that in DNBFL, inducing a high denitrification efficiency in DNBFS.
authors.affiliation: Key Laboratory of Microorganism Application and Risk Control (MARC) of Shenzhen, Graduate School at Shenzhen, Tsinghua University, Shenzhen, Guangdong 518055, China E-mail: wu.guangxue@sz.tsinghua.edu.cn.
authors.forename: Nan
authors.initials: N
authors.lastname: Wei
authors.affiliation: Key Laboratory of Microorganism Application and Risk Control (MARC) of Shenzhen, Graduate School at Shenzhen, Tsinghua University, Shenzhen, Guangdong 518055, China E-mail: wu.guangxue@sz.tsinghua.edu.cn.
authors.forename: Yunhong
authors.initials: Y
authors.lastname: Shi
authors.affiliation: Key Laboratory of Microorganism Application and Risk Control (MARC) of Shenzhen, Graduate School at Shenzhen, Tsinghua University, Shenzhen, Guangdong 518055, China E-mail: wu.guangxue@sz.tsinghua.edu.cn.
authors.forename: Guangxue
authors.initials: G
authors.lastname: Wu
authors.affiliation: Key Laboratory of Microorganism Application and Risk Control (MARC) of Shenzhen, Graduate School at Shenzhen, Tsinghua University, Shenzhen, Guangdong 518055, China E-mail: wu.guangxue@sz.tsinghua.edu.cn.
authors.forename: Hongying
authors.initials: H
authors.lastname: Hu
authors.affiliation: Kunming Dianchi Water Group Co. Ltd., Kunming, Yunnan 650228, China.
authors.forename: Yumei
authors.initials: Y
authors.lastname: Guo
authors.affiliation: Kunming Dianchi Water Group Co. Ltd., Kunming, Yunnan 650228, China.
authors.forename: Yihui
authors.initials: Y
authors.lastname: Wu
authors.affiliation: Kunming Dianchi Water Group Co. Ltd., Kunming, Yunnan 650228, China.
authors.forename: Hui
authors.initials: H
authors.lastname: Wen
mesh_terms: D018441:Biofilms; D018533:Biomass; D019149:Bioreactors; D058440:Denitrification; D009566:Nitrates; D009584:Nitrogen / Q000302:isolation & purification*; D010758:Phosphorus / Q000302:isolation & purification*; D018508:Water Purification / Q000379:methods*
chemical_list: D009566:Nitrates; D010758:Phosphorus; D009584:Nitrogen