%0 Journal Article
%T Anaerobic digestion at high-pH and alkalinity for biomethane production: Insights into methane yield, biomethane purity, and process performance
%A Diniz, B. C.
%A Wilfert, P.
%A Sorokin, D. Y.
%A Loosdrecht, M. C. M. van
%J Bioresource Technology
%D 2025
%V 429
%@ 0960-8524
%F Diniz_etal2025
%O exported from refbase (http://www.uhydro.de/base/show.php?record=305), last updated on Thu, 28 Aug 2025 13:27:30 +0200
%X The role of high-pH conditions in anaerobic digestion (AD) has traditionally been confined to it’s use in pre-treatment processes. However, operating AD at elevated pH and alkalinity offers significant advantages, including in-situ upgrading of biogas to biomethane. This study examines the potential and scalability of AD under these conditions (pH ∼ 9.3; alkalinity ∼ 0.5 eq/L). The substrate used was the alkaline waste generated from the extraction of extracellular polymeric substances (EPS) from aerobic granular sludge (AGS), and the inoculum used was a haloalkaliphile microbial community from soda lake sediments. To evaluate the system’s performance, the organic loading rate (OLR) was incrementally increased. The highest methane production obtained was 8.4 ± 0.1 mL/day/gVSadded at a hydraulic retention time (HRT) of 15 days and an OLR of 1 kgVS/day/m3. At this loading rate, methanogenesis became the rate limiting conversion. The maximum volatile solids conversion was 48.1 ± 1.1 %. Throughout the reactor operation, methane purity in the biogas consistently exceeded 90 % peaking at 96.0 ± 0.2 %, showcasing the potential for in-situ biogas purification under these conditions. In addition, no ammonia inhibition was observed, even with free-ammonia (NH3) concentrations reaching up to 14 mM. This study underscores the potential of high-pH anaerobic digestion as a sustainable method for both waste treatment and energy recovery.
%K Anaerobic digestion
%K High-pH
%K High-alkalinity
%K Biogas upgrading
%K
%K Alkaline waste
%U https://www.sciencedirect.com/science/article/pii/S0960852425004717
%P 132505