Improving and upgrading an existing activated sludge with a compact MBBR - disc filters parallel line for municipal wastewater treatment in touristic alpine areas.

L. Desa, Pille Kängsepp, L. Quadri, G. Bellotti, K. Sorensen, C. Pellicer-Nacher

    Research output: Contribution to journalArticlepeer-review

    1 Citation (Scopus)

    Abstract

    Many wastewater treatment plants (WWTP) in touristic areas struggle to achieve the effluent requirements due to seasonal variations in population. In alpine areas, the climate also determines a low wastewater temperature, which implies long sludge retention time (SRT) needed for the growth of nitrifying biomass in conventional activated sludge (CAS). Moreover, combined sewers generate high flow and dilution. The present study shows how the treatment efficiency of an existing CAS plant with tertiary treatment can be upgraded by adding a compact line in parallel, consisting of a Moving Bed Biofilm Reactor (MBBR)-coagulation-flocculation-disc filtration. This allows the treatment of influent variations in the MBBR and a constant flow supply to the activated sludge. The performance of the new 2-step process was comparable to that of the improved existing one. Regardless significant variations in flow (10,000-25,000 m(3)/d) and total suspended solids (TSS) (50-300 mg/L after primary treatment) the effluent quality fulfilled the discharge requirements. Based on yearly average effluent data, TSS were 11 mg/L, chemical oxygen demand (COD) 27 mg/L and total phosphorus (TP) 0.8 mg/L. After the upgrade, ammonium nitrogen (NH4-N) dropped from 4.9 mg/L to 1.3 mg/L and the chemical consumption for phosphorus removal was reduced.

    Original languageEnglish
    Pages (from-to)515-527
    Number of pages12
    JournalWater Practice and Technology
    Volume15
    Issue number2
    DOIs
    Publication statusPublished - 2020

    Swedish Standard Keywords

    • Natural sciences (1)
    • Engineering and Technology (2)

    Keywords

    • activated sludge
    • alpine climate
    • compact upgrade
    • microscreen
    • moving bed biofilm reactor (MBBR)
    • touristic load variations

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