Special Issue "New Insights on Sludge Fermentation"

A special issue of Fermentation (ISSN 2311-5637). This special issue belongs to the section "Industrial Fermentation".

Deadline for manuscript submissions: 15 November 2023 | Viewed by 3741

Special Issue Editor

State Key Laboratory of Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Tongji University, Shanghai, China
Interests: waste-activated sludge; food waste; anaerobic fermentation; volatile fatty acids

Special Issue Information

Dear Colleagues,

The effective disposal of waste-activated sludge (WAS) has been extremely significant and urgent for the highly efficient operation of wastewater treatment plants considering the increasing amounts of WAS being generated. Meanwhile, scarcity of resources and energy drive the public to seek for more efficient and sustainable treatment approaches for WAS disposal and resource recovery. Anaerobic fermentation has been widely accepted as an effective and eco-friendly strategy for WAS disposal. Indeed, high-value products and energy could be recovered via this process. However, the WAS fermentation performance is restricted by various parameters, such as pH, temperature, sludge retention time, the efficiency of solubilization and hydrolysis, etc. How to effectively improve WAS fermentation efficiency through the development of novel and advanced methods is of vital importance. In parallel, the WAS fermentation is mainly a biological process; hence, the functional microorganisms as well as their metabolic functions and activities play vital roles in the transformation and valorization of WAS. It is also necessary to efficiently regulate and maintain the high metabolic activity and functions of microorganisms involved in WAS fermentation. Also, the disclosure of underlying mechanisms via advanced techniques and methods at the levels of microbial community, metabolic pathways, genetic expression levels were also urgent to uncover. The relevant studies will provide new sights into sludge fermentation and guidance for sludge disposal.

We are inviting research papers and reviews about novel insights on sludge fermentation. The aim of this Special Issue is to provide an insight into the latest findings of sludge fermentation, including the biologically volatile fatty acids, hydrogen and polyhydroxyalkanoates (PHA) production from WAS, and novel and advanced methods for enhancing WAS fermentation efficiency. Moreover, the illustration of the specific microbial functions in microbial consortia, elucidation of the biological principles and main controlling factors that regulate the metabolic bioprocesses, and provision of biotechnological solutions and regulation strategies are also encouraged. If you have any questions, please contact the editor to discuss the topic relevance.

Dr. Yang Wu
Guest Editor

Manuscript Submission Information

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Keywords

  • waste-activated sludge
  • anaerobic fermentation
  • solubilization
  • hydrolysis
  • acidification
  • pretreatment
  • microorganisms
  • metabolic functions
  • volatile fatty acids
  • hydrogens
  • PHA

Published Papers (4 papers)

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Research

Communication
Research on the Promotion of Sludge Anaerobic Fermentation with Sodium Citrate under Low Concentrations of Polyaluminum Chloride
Fermentation 2023, 9(8), 776; https://doi.org/10.3390/fermentation9080776 - 21 Aug 2023
Viewed by 422
Abstract
Polyaluminum chloride (PAC) is used widely and increasingly in wastewater treatment plants, resulting in its inevitably high production in sludge. Previous studies have indicated that the production of short-chain fatty acids (SCFAs) is inhibited by the existence of PAC in sludge anaerobic fermentation, [...] Read more.
Polyaluminum chloride (PAC) is used widely and increasingly in wastewater treatment plants, resulting in its inevitably high production in sludge. Previous studies have indicated that the production of short-chain fatty acids (SCFAs) is inhibited by the existence of PAC in sludge anaerobic fermentation, so it is necessary to study how to promote sludge anaerobic fermentation under low concentrations of PAC. In this study, sodium citrate (SC) was first used to improve the efficiency of anaerobic fermentation under low concentrations of PAC. The results showed that the production of SCFAs increased with SC, especially when the ratio of PAC to SC was 1:2, and the maximum production of SCFAs reached 2890 mg/L, which is 2.5 times more than when PAC only exists. The mechanism studies showed that SC could remove the Al3+ in the sludge floc, which led to deflocculation of the sludge floc, accelerated the destruction of extracellular polymers (EPS), and released soluble substances in the sludge. At the same time, the key enzymes that were bound and hidden originally in the sludge were also released, which promoted the further degradation of organic matter and shortened the anaerobic fermentation period. However, the higher concentration of SC was not conducive to sludge dehydration. Therefore, the optimal distribution ratio of PAC to SC should be 1:1. This study provides a new idea for the research and practical application of sludge anaerobic fermentation. Full article
(This article belongs to the Special Issue New Insights on Sludge Fermentation)
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Article
Bio-Drying of Municipal Wastewater Sludge: Effects of High Temperature, Low Moisture Content and Volatile Compounds on the Microbial Community
Fermentation 2023, 9(6), 570; https://doi.org/10.3390/fermentation9060570 - 16 Jun 2023
Viewed by 740
Abstract
This study examined microbiological processes during the bio-drying of municipal wastewater sludge (WS) from the waste treatment facilities of the Moscow region (Russia). In just 21 days of bio-drying, the moisture content of the mixture of WS and wood chips decreased by 19.7%. [...] Read more.
This study examined microbiological processes during the bio-drying of municipal wastewater sludge (WS) from the waste treatment facilities of the Moscow region (Russia). In just 21 days of bio-drying, the moisture content of the mixture of WS and wood chips decreased by 19.7%. It was found that members of the genus Bacillus were the main organic matter destructors. In the period from 7 to 14 days, the rates of organic matter mineralization and moisture loss were the highest, and bacteria of the genus Bacillus dominated, accounting for 43.5 to 84.6% of the bacterial community with a total number of 1.20 (±0.09) × 106 to 6.70 (±0.44) × 105 gene copies µg−1. The maximum number of Amaricoccus was (15.7% of the total bacterial community) in the middle of bio-drying. There was an active accumulation of nitrate nitrogen due to the oxidation of nitrogen-containing substances during the same period of time. Bacteria of the genera Sphingobacterium, Brevundimonas, Brucella, Achromobacter and fungi of the genus Fusarium dominated in the biofilter, which removed volatile compounds from the waste air by 90%. The obtained results allow to model the further intensification of bio-drying, as well as its efficiency and safety. Full article
(This article belongs to the Special Issue New Insights on Sludge Fermentation)
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Article
Vermi-Conversion of Anaerobic Sludges by Eisenia fetida Earthworms
Fermentation 2023, 9(6), 512; https://doi.org/10.3390/fermentation9060512 - 26 May 2023
Viewed by 584
Abstract
Sludge management is considered a difficult and challenging task and is a priority of environmental policy. This study evaluates the transformation of the anaerobic sludge of agroindustrial wastes (cow manure, anaerobic sludge mixtures) directly to compost using Eisenia fetida earthworms (vermicomposting) in relation [...] Read more.
Sludge management is considered a difficult and challenging task and is a priority of environmental policy. This study evaluates the transformation of the anaerobic sludge of agroindustrial wastes (cow manure, anaerobic sludge mixtures) directly to compost using Eisenia fetida earthworms (vermicomposting) in relation to sludge quality; moreover, it investigates the effects of different sludge compositions on vermicompost physicochemical properties. In particular, the biostabilization of anaerobic sludge (AS1) produced in excess from the wastewater treatment plant (WWTP) of Patras, Greece, and mixed anaerobic sludge (AS2) originating from the effluents of a laboratory anaerobic co-digestion system treating an agroindustrial waste mixture (olive mill wastewater, cheese whey, and liquid cow manure in a ratio of 55: 40: 5 (w/w), respectively) mixed with cow dung (CD) using Eisenia fetida earthworms was examined. Comparing the mixtures of CD-AS1 to CD-AS2, superior results were obtained with the use of AS2 since an increase in N-P-K was observed when either 10% (22%, 51.8%, and 2.4%, respectively) or 15% of AS2 (38.7%, 14.1%, and 8.1% respectively) was used. Although a reduction in earthworms’ growth was observed compared to 100% CD, during the vermicomposting of the CD-AS mixtures, 410 and 250 mg/earthworm was sustained in the mixtures of 85% CD-15% AS2 and 80% CD-20% AS2 after a period of 63 and 70 days of vermicomposting, respectively. Full article
(This article belongs to the Special Issue New Insights on Sludge Fermentation)
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Article
Comparing VFA Composition, Biomethane Potential, and Methane Production Kinetics of Different Substrates for Anaerobic Fermentation and Digestion
Fermentation 2023, 9(2), 138; https://doi.org/10.3390/fermentation9020138 - 31 Jan 2023
Cited by 3 | Viewed by 1174
Abstract
Solid waste is one of the largest sources of greenhouse gases (GHGs) today. The carbon footprint of landfills also has a large impact on global warming. Therefore, it is becoming more urgent to study the possibility of better environmentally friendly approaches for solid [...] Read more.
Solid waste is one of the largest sources of greenhouse gases (GHGs) today. The carbon footprint of landfills also has a large impact on global warming. Therefore, it is becoming more urgent to study the possibility of better environmentally friendly approaches for solid waste management and its safe disposal. The digestion of solid waste is a biological process that breaks down the organic content of the solid waste and thus stabilizes it. It also allows the recovery of valuable resources (such as biogas) and the utilization of stabilized waste in various industries. In this study, six substrates were studied to determine their biomethane potential (BMP) in anaerobic digestion. The substrates were fermented and digested anaerobically, and the biogas production was measured. The methane yield of food waste substrates had a higher methane yield between 354 and 347 mL/g-TCOD, and a biodegradability of 89–87%. Wastewater sludge substrates yielded between 324 and 288 mL/g-TCOD with a biodegradability of 81–73%. A kinetics analysis using first-order and Gompertz models was performed for biodegradation and methane production. Full article
(This article belongs to the Special Issue New Insights on Sludge Fermentation)
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