Changes in anoxic denitrification rate resulting from prefermentation of a septic, phosphorus-limited wastewater

    Authors

    T. McCue; R. Naik; M. Zepeda; Y. H. Liu; I. Vassiliev;A. A. Randall

    Comments

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    Abbreviated Journal Title

    Water Environ. Res.

    Keywords

    biological nutrient removal; phosphorus; prefermentation; volatile fatty; acids; denitrification; enhanced biological phosphorus removal; biological nitrogen removal; REMOVAL; Engineering, Environmental; Environmental Sciences; Limnology; Water; Resources

    Abstract

    A preliminary bench-scale study of parallel University of Cape Town (UCT) biological nutrient removal systems showed improvement in anoxic denitrification rates resulting from prefermentation of a septic (i.e., high volatile fatty acid [VFA] content), phosphorus-limited (i.e., total chemical oxygen demand/total phosphorus [TP] ratio < 40:1) wastewater. Net phosphorus removals due to enhanced biological phosphorus removal (EBPR) were only improved marginally by prefermentation in spite of significant increases in anaerobic phosphorus release, polyhydroxyatkanoate formation, and higher anoxic and aerobic uptakes. This probably was due to the high VFA/TP ratio in the raw influent relative to the VFA requirements for EBPR because enough VFAs were already present for phosphorus removal prior to prefermentation. An additional assessment of prefermentation using parallel UCT systems with step feed of 50% of the influent to the anoxic zone was completed. This second phase quantified the effect of prefermentation in a step-feed scenario, which prioritized prefermentation use to enhance denitrification rather than EBPR. While specific denitrification rates in the anoxic zone were significantly improved by prefermentation, high denitrification in the clarifiers and aerobic zones (simultaneous denitrification) made definitive conclusions concerning the potential improvements in total system nitrogen removal questionable. The prefermented system always showed superior values of the zone settling velocity and sludge volume index and the improvement became increasingly statistically significant when the prefermenter was performing well.

    Journal Title

    Water Environment Research

    Volume

    76

    Issue/Number

    1

    Publication Date

    1-1-2004

    Document Type

    Article

    Language

    English

    First Page

    23

    Last Page

    28

    WOS Identifier

    WOS:000220013400004

    ISSN

    1061-4303

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