TY - JOUR
T1 - Improving and upgrading an existing activated sludge with a compact MBBR
T2 - disc filters parallel line for municipal wastewater treatment in touristic alpine areas
AU - Desa, L.
AU - Kängsepp, Pillä
AU - Quadri, L.
AU - Bellotti, G.
AU - Sorensen, K.
AU - Pellicer-Nacher, C.
PY - 2020
Y1 - 2020
N2 - 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.
AB - 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.
KW - activated sludge
KW - alpine climate
KW - compact upgrade
KW - microscreen
KW - moving bed biofilm reactor (MBBR)
KW - touristic load variations
U2 - 10.2166/wpt.2020.043
DO - 10.2166/wpt.2020.043
M3 - Article
VL - 15
SP - 515
EP - 527
JO - Water Practice and Technology
JF - Water Practice and Technology
SN - 1751-231X
IS - 2
ER -