Effects of substrate loading on co-metabolic transformation pathways and removal rates of pharmaceuticals in biofilm reactors

TY - JOUR

T1 - Effects of substrate loading on co-metabolic transformation pathways and removal rates of pharmaceuticals in biofilm reactors

AU - Liang, Chuanzhou

AU - Carvalho, Pedro N.

AU - Bester, Kai

PY - 2022/12

Y1 - 2022/12

N2 - This study focused on the effects of substrate (raw wastewater) on the biological removal of 20 pharmaceuticals in moving bed biofilm reactors. This is the first study discriminating experimentally between effects of adaptation (45 d) and stimulation (100 h) on the removal of micropollutants. The results presented in this paper show: i) Tramadol and venlafaxine are subject to microbial N-oxidation (besides the known demethylation). ii) Changes in substrate loading, changed the preferential degradation pathways, e.g., from N-oxidation (under starvation) to N-demethylation of both model compounds: tramadol and venlafaxine, during adaptation and stimulation to high substrate supply. iii) In starving biofilms, the effects of stimulation on removal rates are minor (−100 to +150 %) in comparison to those caused by adaptation (−100 to +700 %). iv) Adaptation to high loadings resulted in increased removal rates (up to 700 % in selected cases) v) Adaptation to high loadings followed by high loading of stimulation, resulted in the highest increase of removal rates (+49 % to +1800 %) for hard-to-degrade compounds (e.g., diclofenac). All in all, this study shows that the efficiency of biofilm reactors is heavily dependent on their adaptation to substrate.

AB - This study focused on the effects of substrate (raw wastewater) on the biological removal of 20 pharmaceuticals in moving bed biofilm reactors. This is the first study discriminating experimentally between effects of adaptation (45 d) and stimulation (100 h) on the removal of micropollutants. The results presented in this paper show: i) Tramadol and venlafaxine are subject to microbial N-oxidation (besides the known demethylation). ii) Changes in substrate loading, changed the preferential degradation pathways, e.g., from N-oxidation (under starvation) to N-demethylation of both model compounds: tramadol and venlafaxine, during adaptation and stimulation to high substrate supply. iii) In starving biofilms, the effects of stimulation on removal rates are minor (−100 to +150 %) in comparison to those caused by adaptation (−100 to +700 %). iv) Adaptation to high loadings resulted in increased removal rates (up to 700 % in selected cases) v) Adaptation to high loadings followed by high loading of stimulation, resulted in the highest increase of removal rates (+49 % to +1800 %) for hard-to-degrade compounds (e.g., diclofenac). All in all, this study shows that the efficiency of biofilm reactors is heavily dependent on their adaptation to substrate.

KW - Co-metabolism

KW - Moving bed biofilm reactor

KW - Pharmaceuticals

KW - Rate constant

KW - Transformation product

KW - Wastewater treatment

UR - http://www.scopus.com/inward/record.url?scp=85138085177&partnerID=8YFLogxK

U2 - 10.1016/j.scitotenv.2022.158607

DO - 10.1016/j.scitotenv.2022.158607

M3 - Journal article

C2 - 36089036

AN - SCOPUS:85138085177

SN - 0048-9697

VL - 853

JO - Science of the Total Environment

JF - Science of the Total Environment

M1 - 158607

ER -