TY - JOUR
T1 - Short sludge age denitrification as alternative process for energy and nutrient recovery
AU - Tirkey, Vishal
AU - Goonesekera, Estelle M.
AU - Kovalovszki, Adam
AU - Smets, Barth F.
AU - Dechesne, Arnaud
AU - Valverde-Pérez, Borja
PY - 2022
Y1 - 2022
N2 - High rate activated sludge (HRAS) systems redirect organics into highly biodegradable sludge and nutrients into microbial proteins. This study evaluates anoxic HRAS for nitrogen and carbon recovery. The reactor treated synthetic wastewater at solids retention times (SRTs) of 5, 3 and 1 days. Denitrification rates varied between 0.15 and 0.19 g-NO3-N g-TSS-1 d-1 (total suspended solids per day) and all conditions showed favourable settling. The highest sludge yield, obtained at SRT 1 d, was 0.75 g-TSS g-COD-1removed, double that observed for aerobic HRAS. The highest methane yield (322 mL-CH4 g-VS-1sludge) was obtained from sludge wasted at 3 d SRT. Both 1 d and 3 d SRTs showed favourable energy recovery, with 14 % of the organics recovered as methane. All conditions yielded sludge with protein content ranging between 24 and 27 % of dry weight and similar amino acid profile, comparable to traditional proteins. Thus, denitrifying HRAS recovers resources as its aerobic counterpart, allowing for nitrogen removal via denitrification, more stable compared to mainstream partial nitritation anammox typically combined with aerobic HRAS.
AB - High rate activated sludge (HRAS) systems redirect organics into highly biodegradable sludge and nutrients into microbial proteins. This study evaluates anoxic HRAS for nitrogen and carbon recovery. The reactor treated synthetic wastewater at solids retention times (SRTs) of 5, 3 and 1 days. Denitrification rates varied between 0.15 and 0.19 g-NO3-N g-TSS-1 d-1 (total suspended solids per day) and all conditions showed favourable settling. The highest sludge yield, obtained at SRT 1 d, was 0.75 g-TSS g-COD-1removed, double that observed for aerobic HRAS. The highest methane yield (322 mL-CH4 g-VS-1sludge) was obtained from sludge wasted at 3 d SRT. Both 1 d and 3 d SRTs showed favourable energy recovery, with 14 % of the organics recovered as methane. All conditions yielded sludge with protein content ranging between 24 and 27 % of dry weight and similar amino acid profile, comparable to traditional proteins. Thus, denitrifying HRAS recovers resources as its aerobic counterpart, allowing for nitrogen removal via denitrification, more stable compared to mainstream partial nitritation anammox typically combined with aerobic HRAS.
KW - Resource recovery
KW - High rate denitrifying sludge
KW - Biogas
KW - Microbial protein
U2 - 10.1016/j.biortech.2022.128184
DO - 10.1016/j.biortech.2022.128184
M3 - Journal article
C2 - 36283659
SN - 0960-8524
VL - 366
JO - Bioresource Technology
JF - Bioresource Technology
M1 - 128184
ER -