Coliform die-off rate constants in a high rate algal pond and the effect of operational and environmental variables

H. J. Fallowfield, N. J. Cromar, L. M. Evison

    Research output: Contribution to journalConference article

    33 Citations (Scopus)

    Abstract

    High rate algal ponds (HRAPs) are an adaptation of waste stabilization ponds, in which increased treatment efficiency and reduced pond area are achieved by optimizing conditions for algal photosynthetic oxygen production. If the treated effluent is subsequently to be reused for irrigation of crops and recreational areas, from a public health viewpoint it is important to reduce the risk of contamination by pathogenic organisms. The microbiological quality of effluents is traditionally assessed by enumerating the coliform group of organisms. Die-off rate constants (Kb) of 0.35 - 2.34 d-1 were measured for E. coli in outdoor ponds operating on synthetic sewage mix with acetate as the carbon source (260 kg COD ha-1 d-1) at a range of depths from 12 to 34 cm. There were significant positive effects of pH, irradiance and pond depth on Kb. Light penetration throughout the pond depth was calculated and shown to be a useful parameter for the prediction of Kb. Multiple regression equations describing the influence of these environmental parameters on die-off rate constant were derived. Dry matter concentration negatively affected light penetration but had a positive influence upon pH. Pond operating conditions to maximize E. coli die-off are discussed.

    Original languageEnglish
    Pages (from-to)141-147
    Number of pages7
    JournalWater Science and Technology
    Volume34
    Issue number11
    DOIs
    Publication statusPublished - 1 Jan 1996
    EventProceedings of the 18th Biennial Conference of the International Association on Water Quality. Part 8 - Singapore, Singapore
    Duration: 23 Jun 199628 Jun 1996

    Keywords

    • Depth
    • Die-off rate constant
    • E. coli
    • High rate algal ponds
    • Irradiance
    • Light penetration
    • Pathogen removal
    • pH
    • Wastewater treatment

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