Distinct effects of conductive materials on anaerobic sulfate-rich wastewater treatment under varying operational modes.

Conductive materials (CMs) have shown great potential in enhancing anaerobic digestion of sulfate-rich wastewater by improving electron transfer. However, how the effectiveness of CMs varies under different reactor operational modes that shape microbial communities and influence system performance remains poorly understood. This study systematically compared sequencing batch reactors (SBRs) and continuous-flow reactors (CFRs) amended with magnetite (Fe₃O₄) or powdered activated carbon (PAC) for treating sulfate-rich wastewater.

Tetracycline in anaerobic digestion: Microbial inhibition, removal pathways, and conductive material mitigation.

Tetracycline enters the environment due to its incomplete absorption in humans and animals, posing a significant ecological threat. Tetracycline can hinder the biosystems when treating tetracycline-containing wastewater/waste through anaerobic digestion. This review summarizes the role of tetracycline in inhibiting system performance and related functional microorganisms in holistic process of anaerobic digestion.

Ethanol metabolism in anaerobic digestion systems for better renewable energy recovery from waste feedstocks.

Ethanol plays a key role in advancing the sustainable technology of anaerobic digestion. A comprehensive understanding of ethanol metabolism is essential for optimizing the enhanced recovery of renewable energy from waste feedstocks via anaerobic digestion. This review aims to summarize key findings on ethanol metabolism, focusing on metabolic pathways, kinetics and ecological applications, as well as functional microorganisms and their enrichment strategies.

Enhancement of volatile fatty acids degradation and rapid methanogenesis in a biochar-assisted anaerobic membrane bioreactor via enhancing direct interspecies electron transfer.

In this investigation, we assessed the efficacy of a biochar-supported anaerobic membrane bioreactor (BC-AnMBR) for continuously treating swine wastewater (SWW) under varying NH-N stress levels. Our findings revealed that as the NH-N concentration escalated from 440 mg/L to 1400 mg/L, the BC-AnMBR exhibited a notable 14.5 % improvement in NH-N removal under heightened ammonia pressure compared to the conventional AnMBR (CG-AnMBR).

CFD modelling and simulation of anaerobic digestion reactors for energy generation from organic wastes: A comprehensive review.

Anaerobic digestion (AD) has been recognized as one of the most viable options for the treatment of a wide range of waste materials. Complex structure of wastes is safely broken down to destroy pollutants and pathogens. Biogas is produced as a by-product of this process which is considered as a clean energy resource.

Microbial transitions and degradation pathways driven by butyrate concentration in mesophilic and thermophilic anaerobic digestion under low hydrogen partial pressure.

Butyrate accumulation significantly affects the efficiency and stability of anaerobic digestion, while its specific impact on methane yield and butyrate degradation remains unclear. This study investigated how butyrate concentrations (2.0, 5.

Strategies for enriching targeted sulfate-reducing bacteria and revealing their microbial interactions in anaerobic digestion ecosystems.

Deciphering relationships between sulfate-reducing bacteria (SRB) and other microorganisms is crucial for stable operation of anaerobic digestion systems when treating sulfate-containing wastewater. However, few studies have differentiated the incomplete oxidizing SRB (IO-SRB) and complete oxidizing SRB (CO-SRB) in anaerobic digestion ecosystems. Four ethanol-fed bioreactors were operated under two operational modes (sequencing batch reactor, SBR; and continuous-flow reactor, CFR) and two chemical oxygen demand (COD) to sulfate ratios (1 and 2) to systematically explore strategies for enriching IO-SRB and/or CO-SRB and their microbial interactions with other microorganisms.

Unacclimated activated sludge improved nitrate reduction and N selectivity in iron filling/biochar systems.

Iron (Fe)-based denitrification is a proven technology for removing nitrate from water, yet challenges such as limited pH preference range and low N selectivity (reduction of nitrate to N) persist. Adding biochar (BC) can improve the pH preference range but not N selectivity. This study aimed to improve nitrate reduction and N selectivity in iron filling/biochar (Fe/BC) systems with a simplified approach by coupling unacclimated microbes (M) in the system.

Mechanistic understanding of acclimation and energy metabolism of acetoclastic methanogens under different substrate to microorganism ratios.

Mechanistic understanding of acetoclastic methanogenesis is pivotal for optimizing anaerobic digestion for efficient methane production. In this study, two different operational modes, continuous flow reactor (CFR) and sequencing batch reactor (SBR), accompanied with solids retention times (SRT) of 10 days (SBR and CFR) and 25 days (SBR and CFR) were implemented to elucidate their impacts on microbial communities and energy metabolism of methanogens in acetate-fed systems. Microbial community analysis revealed that the relative abundance of Methanosarcina (16.

Powdered activated carbon facilitated degradation of complex organic compounds and tetracycline in stressed anaerobic digestion systems.

Tetracycline exerts an inhibitory effect on anaerobic digestion, inducing stressed microbial activities and even system failure. Continuous-flow reactors (CFRs) and sequencing batch reactors (SBRs) were employed along with the dosage of powdered activated carbon (PAC) to enhance tetracycline removal during anaerobic digestion of complex organic compounds. PAC increased the maximum methane production rate by 15.

Operational mode and powdered activated carbon promoting syntrophic propionate oxidation during anaerobic digestion of complex organic substances.

Operational mode and powdered activated carbon (PAC) are key factors facilitating microbial syntrophy and interspecies electron transfer during anaerobic digestion, consequently benefiting process stability and efficient methanogenesis. In this study, continuous-flow reactor (CFR) and sequencing batch reactor (SBR), with and without the addition of PAC, respectively, were operated to examine their effects on system performance and methanogenic activity. Based on the cycle-test result, the PAC-amended CFR (CFR) recorded both the highest methane yield (690.

Deciphering anaerobic ethanol metabolic pathways shaped by operational modes.

Efficient anaerobic digestion requires the syntrophic cooperation among diverse microorganisms with various metabolic pathways. In this study, two operational modes, i.e.

Role of suspended solids on the co-precipitation of pathogenic indicators and antibiotic resistance genes with struvite from digested swine wastewater.

Struvite recovered from wastewater contains high concentration of fecal indicator bacteria (FIB), porcine adenoviruses (PAdV) and antibiotic resistance genes (ARGs), becoming potential resources of these microbial hazards. Understanding the precipitation behavior of pathogenic indicators and ARGs with suspended solids (SS) will provide the possible strategy for the control of co-precipitation. In this study, SS was divided into high-density SS (separated by centrifugation) and low-density SS (further separated by filtration), and the role of SS on the co-precipitation of FIB, PAdV and ARGs was investigated.

Revealing impacts of operational modes on anaerobic digestion systems coupling with sulfate reduction.

Anaerobic digestion (AD) is promising for treating high-strength wastewater. However, the effect of operational parameters on microbial communities of AD with sulfate is not yet fully understood. To explore this, four reactors were operated under rapid- and slow-filling modes with different organic carbons.

Co-precipitation of heavy metals with struvite from digested swine wastewater: Role of suspended solids.

Struvite production can recover ammonia and phosphorous from digested wastewater as fertilizer. During struvite generation, most of the heavy metals was co-precipitated with ammonia and phosphorous into struvite. Understanding the precipitation behavior of heavy metals with suspended solids (SS) might provide the possible strategy for the control of co-precipitation.

Quorum sensing responses of r-/K-strategists Nitrospira in continuous flow and sequencing batch nitrifying biofilm reactors.

A better understanding of r-/K-strategists nitrifiers will help to balance the design and operation of bioprocesses for efficient pollution removal from wastewater. The objectives of study were to investigate the nitrite oxidation biokinetics, biofilm property, microbial community and quorum sensing (QS) of nitrifying biofilm in a continuously flow reactor (CFR) and a sequencing batch reactor (SBR). Results showed that nitrite-oxidizing bacteria were estimated to have a nitrite half saturation constant of 76.

Ca(ClO) pretreatment enhancing suspended solids removal through flocculation from digested dairy wastewater and its mechanisms.

Intensive animal farming produces large volume of digested liquid, and overdose application often causes the pollution of surface water and groundwater. Therefore, post-treatment is very necessary for the discharging of surplus digested liquid, but the removal of high concentrations of suspended solids (SS) in the digested liquid is a challenge. In this study, the effect of Ca(ClO) pretreatment on SS flocculation removal of digested dairy wastewater was investigated.

Distinguishing responses of acetoclastic and hydrogenotrophic methanogens to ammonia stress in mesophilic mixed cultures.

A shift from the acetoclastic to the hydrogenotrophic pathway in methanogenesis under ammonia inhibition is a common observation in anaerobic digestion. However, there are still considerable knowledge gaps concerning the differential ammonia tolerance of acetoclastic and hydrogenotrophic methanogens (AMs and HMs), their responses to different ammonia species (NH, NH), and their recoverability after ammonia inhibition. With the successful enrichment of mesophilic AMs and HMs cultures, this study aimed at addressing the above knowledge gaps through batch inhibition/recovery tests and kinetic modeling under varying total ammonia (TAN, 0.

Role of iron(II) sulfide in autotrophic denitrification under tetracycline stress: Substrate and detoxification effect.

Autotrophic denitrification using inorganic compounds as electron donors has gained increasing attention in the field of wastewater treatment due to its numerous advantages, such as no need for exogenous organic carbon, low energy input, and low sludge production. Tetracycline (TC), a refractory contaminant, is often found coexisting with nutrients (NO and PO) in wastewater, which can negatively affect the biological nutrient removal process because of its biological toxicity. However, the performance of autotrophic denitrification under TC stress has rarely been reported.

Distribution of extracellular amino acids and their potential functions in microbial cross-feeding in anaerobic digestion systems.

Anaerobic digestion is a prevalent bioenergy production process relying on a complex network of symbiotic interactions, where the nutrient based cross-feeding is an essential microbial mechanism. Here, the cross-feeding function was assessed by analyzing extracellular polymeric substances-associated amino acids in microbial aggregates collected from 14 lab-scale anaerobic digesters, as well as deciphering their genetically biosynthetic potential by syntrophic bacteria and methanogens. The total concentration of essential amino acids ranged from 1.

Greenhouse gas emissions from municipal wastewater treatment facilities in China from 2006 to 2019.

Wastewater treatment plants (WWTPs) alleviate water pollution but also induce resource consumption and environmental impacts especially greenhouse gas (GHG) emissions. Mitigating GHG emissions of WWTPs can contribute to achieving carbon neutrality in China. But there is still a lack of a high-resolution and time-series GHG emission inventories of WWTPs in China.

Synergistic ammonia and nitrate removal in a novel pyrite-driven autotrophic denitrification biofilter.

Pyrite is one kind of cost-effective electron donors for nitrate denitrification. In this study, a pyrite-driven autotrophic denitrification biofilter was applied for simultaneous removal of NH and NO over the 150-day. The influent NH/NO ratio (0.

The r/K selection theory and its application in biological wastewater treatment processes.

Understanding the characteristics of functional organisms is the key to managing and updating biological processes for wastewater treatment. This review, for the first time, systematically characterized two typical types of strategists in wastewater treatment ecosystems via the r/K selection theory and provided novel strategies for selectively enriching microbial community. Functional organisms involved in nitrification (e.

Stimulatory effects of biochar addition on dry anaerobic co-digestion of pig manure and food waste under mesophilic conditions.

The stimulatory effect of biochar addition on dry anaerobic digestion (AD) has been rarely investigated. In this study, the effects of commonly used biochars (bamboo, rice husk, and pecan shell) on dry co-AD were investigated using mesophilic batch digesters fed with pig manure and food waste as substrates. The results show that the specific methane yield was mildly elevated with the addition of biochars by 7.