Abstract
The solids retention time of anaerobic digesters is one of the most important parameters for operational and design purposes. It has been believed to have the potential for process intensification with thermal hydrolysis pretreatment upstream. To assess the extent and impact of digester solids retention time reduction, the digestibility and dewaterability of three pilot-scale, continuous flow, mesophilic anaerobic digesters operating at 15-, 12.5-, and 10-day SRT were evaluated. These 10-liter digesters were fed with 9% total solids CAMBITM THP-processed primary and wasted activated sludge every day for nearly a year. The study revealed that shortening the solids retention time from 15 to 10 days linearly decreased volatile solids reduction from 60.7% to 53.6%, highlighting the reduction in hydrolysis rate as the major drawback. However, other digester performance parameters such as methane yield, rheology, and dewaterability largely remained unchanged.
The solids retention time in anaerobic digesters has long been considered as a potential parameter for process intensification, particularly with the installation of thermal hydrolysis pretreatment upstream. This pilot study aims to assess the impact of further reducing digester SRT from 15 to 12.5 days and then to 10 days on the digestibility and dewaterability. It is anticipated to provide engineering guidance for utilities that consider pursuing process intensification of THP-AD systems.
Author(s)Y. Li 1; H. Luo 1 ; M. Strawn 2; L. Racey 2; F. Haile 3; B. Balchunas 4; C. Moline 4; L. Hentz 4; Z. Wang 1; Y. Li 1;
Author affiliation(s)Department of Civil and Environmental Engineering, Virginia Tech 1; Department of Civil and Environmental Engineering, Virginia Tech, Blacksburg, Virginia 24061, United States 1 ; Arlington County Water Pollution Control Bureau 2; Arlington County Water Pollution Control Bureau 2; Arlington County Water Pollution Control Bureau 3; HDR 4; HDR Engineering, Inc. 4; HDR Engineering 4; Department of Biological Systems Engineering, Virginia Tech 1; 1;
SourceProceedings of the Water Environment Federation
Document typeConference Paper
Print publication date Oct 2023
DOI10.2175/193864718825159151
Volume / Issue
Content sourceWEFTEC
Copyright2023
Word count22