Bacterial biomass was characterised in supernatants from activated sludge from a nutrient removal plant after settling before and after applying gentle shear (G approximately 600 s(-1)). Free-swimming and floc-associated bacteria were quantified by microscopy and their identity was determined by fluorescence in-situ hybridization (FISH). Total cell numbers in the supernatant after settling ranged within 2-9 x 10(7)cells/mL. Most cells (60-70%) were associated with microcolonies or small flocs, which made up 5-10% of the total number of particles. The remaining 30-40% of the cells corresponded to free-swimming, single cells. The small flocs in the supernatants (diameter=2.5-35 microm) accounted only for approximately 1% of the total number of particles; however, they greatly contributed to the total volume of biomass in suspension (57% and 75%). The shear applied (G approximately 600 s(-1)) induced some floc detachment and higher cell numbers in the supernatants (10-70 x 10(7)cells/mL). The identity of bacteria in suspension was as diverse as that in the settled sludge; however, bacteria belonging to Planctomycetes, Firmicutes and Deltaproteobacteria were in higher abundance in the sludge supernatants and were enriched in the supernatants due to gentle shear. Potentially active bacteria were quantified based on the ratio of the number of cells fluorescing with the EUBmix gene probe targeting most bacteria to the total number of cells stained with DAPI. Lower ratios of EUBmix to total cells were measured in the supernatants (50%) than in the settled sludge (80%), suggesting that cells in the dispersed fraction of the sludge were potentially less active than those in the average settleable floc. In conclusion, the attachment properties of bacteria in activated sludge were different among groups, rendering floc fractions more susceptible to detachment and suspension depending on their abundance and activity level.
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http://dx.doi.org/10.1016/j.watres.2007.08.026 | DOI Listing |
J Microsc
January 2025
Ningbo Key Laboratory of Micro-Nano Motion and Intelligent Control, Ningbo University, Ningbo, PR China.
The types and quantities of microorganisms in activated sludge are directly related to the stability and efficiency of sewage treatment systems. This paper proposes a sludge microorganism detection method based on microscopic phase contrast image optimisation and deep learning. Firstly, a dataset containing eight types of microorganisms is constructed, and an augmentation strategy based on single and multisamples processing is designed to address the issues of sample deficiency and uneven distribution.
View Article and Find Full Text PDFJ Environ Manage
January 2025
Biogas Institute of Ministry of Agriculture and Rural Affairs, Chengdu, 610041, PR China; Laboratory of Development and Application of Rural Renewable Energy, Ministry of Agriculture and Rural Affairs, Chengdu, 610041, PR China. Electronic address:
To solve the problem of low chemical oxygen demand (COD)/N and poor efficiency of single-stage sequencing batch reactor (SBR) or anoxic/oxic process (A/O) in treatment of digested effluent of swine wastewater, combined SBR-A/O and A/O-SBR processes were employed in the addition ratios of 0, 10%, 30%, and 40% (V/V)) of raw swine wastewater (RS). Analysis of pollutants removal performance of SBR-A/O and A/O-SBR systems showed no significant difference between the two systems without RS addition. However, after adding RS, the pollutants removal efficiency of the two systems increased with the increase in the ratio of RS, with SBR-A/O system presenting better pollutants removal performance than A/O-SBR system.
View Article and Find Full Text PDFFront Plant Sci
January 2025
College of Horticulture, Hebei Agricultural University, Baoding, China.
Continuous cropping has emerged as a significant challenge affecting yield and quality in greenhouse strawberries, particularly as the cultivation of strawberries as a protected crop continues to increase. To address this issue, substrates with 0 or 2 years of continuous cropping were fertilized with two types of organic materials: vermicompost derived from either sludge or cattle manure. A control group consisted of substrate without the addition of vermicompost.
View Article and Find Full Text PDFBiotechnol Appl Biochem
January 2025
Department of Civil Engineering, Guru Ghasidas Vishwavidyalaya, Bilaspur, Chhattisgarh, India.
This study evaluates the efficacy of garbage enzyme (GE) in bioremediation to reduce pollutants in sewage drains that discharge into the natural streams and rivers. Garbage enzyme is prepared with help of brown sugar, fruit, vegetable wastes, and water in the proportion 1:3:10 (by weight), which is then applied to the samples collected from various drainage sites in Jaunpur district, Uttar Pradesh, India. Different concentrations of GE (ranging from 0% to 20%) are mixed with sewage to assess pollution reduction.
View Article and Find Full Text PDFEnviron Microbiome
January 2025
Basecamp Research Ltd, Unit 510 Clerkenwell Workshops, 27 Clerkenwell Close, London, EC1R 0AT, UK.
Background: Despite being recognised as a global problem, our understanding of human-mediated antimicrobial resistance (AMR) spread to remote regions of the world is limited. Antarctica, often referred to as "the last great wilderness", is experiencing increasing levels of human visitation through tourism and expansion of national scientific operations. Therefore, it is critical to assess the impact that these itinerant visitors have on the natural environment.
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