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Water 2014, 6(5), 1300-1311; doi:10.3390/w6051300
Article

Tertiary Denitrification of the Secondary Effluent by Denitrifying Biofilters Packed with Different Sizes of Quartz Sand

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Received: 1 March 2014; in revised form: 18 April 2014 / Accepted: 29 April 2014 / Published: 13 May 2014
(This article belongs to the Special Issue Wastewater Treatment and Reuse)
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Abstract: Tertiary denitrification of the secondary effluent in wastewater treatment plants is necessary to control the eutrophication of receiving water bodies. Two denitrifying biofilters (DNBF), one packed with quart sand with sizes of 2–4 mm (DNBFS) and the other of 4–6 mm (DNBFL), were operated for tertiary denitrification under empty bed retention times (EBRTs) of 30 min, 15 min and 7.5 min, respectively. Under EBRTs of 30 min, 15 min and 7.5 min, the NO3-N removal percentages were 93%, 82% and 83% in DNBFS, and were 92%, 68% and 36% in DNBFL, respectively. The nitrogen removal loading rates increased with decreasing EBRTs, and at the EBRT of 7.5 min, the rate was 2.15 kg/(m3·d) in DNBFS and 1.08 kg/(m3·d) in DNBFL. The half-order denitrification coefficient of DNBFS increased from 0.42 (mg/L)1/2/min at the EBRT of 30 min to 0.70 (mg/L)1/2/min at the EBRT of 7.5 min, while did not vary much in DNBFL with values from 0.22 to 0.25 (mg/L)1/2/min. The performance of both DNBFs was stable within each backwashing cycle, with the NO3-N removal percentage variation within 5%. Better denitrification was achieved in DNBFS but with a slightly high decreased flow rate during the operation.
Keywords: tertiary denitrification; denitrifying biofilters; media size; secondary effluent; empty bed retention times tertiary denitrification; denitrifying biofilters; media size; secondary effluent; empty bed retention times
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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MDPI and ACS Style

Wei, N.; Shi, Y.; Wu, G.; Hu, H.; Wu, Y.; Wen, H. Tertiary Denitrification of the Secondary Effluent by Denitrifying Biofilters Packed with Different Sizes of Quartz Sand. Water 2014, 6, 1300-1311.

AMA Style

Wei N, Shi Y, Wu G, Hu H, Wu Y, Wen H. Tertiary Denitrification of the Secondary Effluent by Denitrifying Biofilters Packed with Different Sizes of Quartz Sand. Water. 2014; 6(5):1300-1311.

Chicago/Turabian Style

Wei, Nan; Shi, Yunhong; Wu, Guangxue; Hu, Hongying; Wu, Yihui; Wen, Hui. 2014. "Tertiary Denitrification of the Secondary Effluent by Denitrifying Biofilters Packed with Different Sizes of Quartz Sand." Water 6, no. 5: 1300-1311.


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