TY - JOUR
T1 - Synergizing carbon and phosphorus recovery from wastewater
T2 - Integrating biofilm-based phosphorus removal in high-rate activated sludge
AU - Sandeep, Rellegadla
AU - Madsen, Jakob Schelde
AU - Marzocchi, Ugo
AU - Vergeynst, Leendert
N1 - Copyright © 2025 The Author(s). Published by Elsevier Ltd.. All rights reserved.
PY - 2025/3/24
Y1 - 2025/3/24
N2 - High-rate activated sludge operated at <2 days biomass age enhances carbon recovery from wastewater, but simultaneous biological recovery of phosphorus remains unachieved. Addressing the reported loss of phosphorus accumulating organisms (PAO) at such short biomass ages, this study investigated the integration of moving bed biofilms into high-rate activated sludge to enhance PAO retention. The results demonstrated sustained biofilm-based PAO activity and complete orthoP removal under short anaerobic-aerobic cycles with a hydraulic retention time of 2.7 h matching high-rate conditions. When combined with high-rate activated sludge in a sequencing batch reactor fed with acetate, complete orthoP removal was sustained. However, using synthetic wastewater promoted the growth of competing heterotrophic bacteria, reducing orthoP removal to 50–65 %. Biofilms served as a continuous source of PAO for the suspended biomass, which contributed to 46–55 % of the overall orthoP removal, even below 2 days biomass age. While acetate-fed microbial communities included known PAOs, using complex feed shifted the community toward less understood putative PAOs. Competition for acetate was likely compensated by a high fermentability of high-rate activated sludge, as PAO activity was maintained while reducing the acetate load in the feed from 20:1 to 5:1 g acetate⋅g P-1. P release and uptake rates were accurately described by the biomass-specific acetate loading rate and the depletion of intracellular polyphosphate, respectively, providing predictive relationships for process optimization. Imposing an anaerobic-aerobic regime enhanced the carbon recovery of high-rate activated sludge from about 37 to 60 %. Integrating biofilms enabled efficient phosphorus removal while maintaining carbon recovery rates of 41–53 %, highlighting the synergistic benefits of this approach.
AB - High-rate activated sludge operated at <2 days biomass age enhances carbon recovery from wastewater, but simultaneous biological recovery of phosphorus remains unachieved. Addressing the reported loss of phosphorus accumulating organisms (PAO) at such short biomass ages, this study investigated the integration of moving bed biofilms into high-rate activated sludge to enhance PAO retention. The results demonstrated sustained biofilm-based PAO activity and complete orthoP removal under short anaerobic-aerobic cycles with a hydraulic retention time of 2.7 h matching high-rate conditions. When combined with high-rate activated sludge in a sequencing batch reactor fed with acetate, complete orthoP removal was sustained. However, using synthetic wastewater promoted the growth of competing heterotrophic bacteria, reducing orthoP removal to 50–65 %. Biofilms served as a continuous source of PAO for the suspended biomass, which contributed to 46–55 % of the overall orthoP removal, even below 2 days biomass age. While acetate-fed microbial communities included known PAOs, using complex feed shifted the community toward less understood putative PAOs. Competition for acetate was likely compensated by a high fermentability of high-rate activated sludge, as PAO activity was maintained while reducing the acetate load in the feed from 20:1 to 5:1 g acetate⋅g P-1. P release and uptake rates were accurately described by the biomass-specific acetate loading rate and the depletion of intracellular polyphosphate, respectively, providing predictive relationships for process optimization. Imposing an anaerobic-aerobic regime enhanced the carbon recovery of high-rate activated sludge from about 37 to 60 %. Integrating biofilms enabled efficient phosphorus removal while maintaining carbon recovery rates of 41–53 %, highlighting the synergistic benefits of this approach.
KW - Biofilm
KW - Enhanced biological phosphorus removal
KW - High-rate activated sludge
KW - Phosphorus accumulating organisms
KW - Resource recovery
KW - Wastewater
UR - http://www.scopus.com/inward/record.url?scp=105001340048&partnerID=8YFLogxK
U2 - 10.1016/j.watres.2025.123546
DO - 10.1016/j.watres.2025.123546
M3 - Journal article
C2 - 40174422
SN - 0043-1354
VL - 280
JO - Water Research
JF - Water Research
M1 - 123546
ER -