Vacuum degassing of activated sludge was tested at eight different Swedish wastewater treatment plants with laboratory-scale equipment in batch mode in order to evaluate its efficiency on improvement of sludge compaction and settling properties. The results show that the efficiency of the degassing technique is mainly dependent on the initial sludge volume index (SVI) of the target sludge which was found to be related to its process configuration. Facilities with full activated sludge-based nitrogen removal processes, including both nitrification and denitrification, had high SVIs (>300 mL g) and were strongly affected by vacuum degassing with reduction of SVI up to 30%. Nitrogen removal facilities also including biological phosphorus removal showed better compaction and settling properties with relatively lower SVIs and were affected to a lesser extent by degassing with SVI reduction of 10-20%. Wastewater treatment plants without full biological nitrogen removal, lacking either nitrification or denitrification (or both) processes in the activated sludge had the lowest SVIs observed with almost no effect of vacuum degassing.
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http://dx.doi.org/10.1080/09593330.2016.1251498 | DOI Listing |
Environ Microbiol
January 2025
Department of Civil, Environmental, and Geo-Engineering, University of Minnesota, Minneapolis, Minnesota, USA.
Shotgun and proximity-ligation metagenomic sequencing were used to generate thousands of metagenome assembled genomes (MAGs) from the untreated wastewater, activated sludge bioreactors, and anaerobic digesters from two full-scale municipal wastewater treatment facilities. Analysis of the antibiotic resistance genes (ARGs) in the pool of contigs from the shotgun metagenomic sequences revealed significantly different relative abundances and types of ARGs in the untreated wastewaster compared to the activated sludge bioreactors or the anaerobic digesters (p < 0.05).
View Article and Find Full Text PDFEnviron Res
January 2025
Research & Development Institute in Shenzhen, School of Chemistry and Chemical Engineering, Northwestern Polytechnical University, China. Electronic address:
Adding additives exogenously is an effective strategy to enhance methanogenic activity and improve AD stability. Corn straw-based biochar@MIL-88A(Fe) (BM) was synthesized herewith and used as an exogenous additive to boost methane (CH) production. After adding BM at 250 mg/g WAS VS, the accumulative CH production and maximum CH yield increased by 1.
View Article and Find Full Text PDFEnviron Pollut
January 2025
College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China.
Sludge landfilling is widely used in China, accounting for approximately 65% of total sludge disposal, due to its simplicity and cost-effectiveness. However, with increasing land scarcity and stricter environmental regulations, the Chinese government has emphasized reducing sludge landfilling. Despite these efforts, sludge historically disposed of in landfills continues to pose risks, including heavy metal leaching and contamination of groundwater and soil.
View Article and Find Full Text PDFBioresour Technol
January 2025
Faculty of Geosciences and Civil Engineering Kanazawa University Kanazawa Japan. Electronic address:
Mitigating the release of extracellular antimicrobial resistance genes (exARGs) from wastewater treatment plants (WWTPs) is crucial for preventing the spread of antimicrobial resistance from human domains into the environment. This study aimed to evaluate the applicability of intI1 as a performance indicator for securing the removal of exARGs at WWTPs. We investigated the reduction of exARGs and intI1 in a full-scale WWTP, where identical wastewater was treated using conventional activated sludge (CAS) and membrane bioreactor (MBR) systems.
View Article and Find Full Text PDFBioresour Technol
January 2025
School of Environment and Ecology, Jiangnan University, Wuxi 214122 China; Jiangsu Collaborative Innovation Center of Water Treatment Technology and Material, Suzhou University of Science and Technology, Suzhou 215011 China. Electronic address:
Caproic acid has broad applications and can be produced from activated sludge via fermentation, but its quality is hindered by ammonia (NH-N) and reactive phosphorus (RP) in the fermentation broth. However, flow-electrode capacitive deionization (FCDI), a novel ion separation technology that operates continuously without secondary pollution seems to be an efficient process that separates the ions. The results showed that at pH 5.
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