PFAS in landfill leachate: Practical considerations for treatment and characterization.

Per- and polyfluoroalkyl substances (PFAS) are widely used in consumer products and are particularly high in landfill leachate. The practice of sending leachate to wastewater treatment plants (WWTPs) is an issue for utilities that have biosolids land application limits based on PFAS concentrations. Moreover, landfills may face their own effluent limit guidelines for PFAS.

Quantifying Elastic Properties of Environmental Biofilms using Optical Coherence Elastography.

Biofilms are complex biomaterials comprising a well-organized network of microbial cells encased in self-produced extracellular polymeric substances (EPS). This paper presents a detailed account of the implementation of optical coherence elastography (OCE) measurements tailored for the elastic characterization of biofilms. OCE is a non-destructive optical technique that enables the local mapping of the microstructure, morphology, and viscoelastic properties of partially transparent soft materials with high spatial and temporal resolution.

Partial Nitritation/Anammox and biological phosphorus removal integration in a single bioreactor under mainstream conditions.

Anammox-based nitrogen removal and enhanced biological phosphorus removal (EBPR) are increasingly applied for nutrient removal from wastewater, but are typically operated in separate reactors. Here, a novel process for integrated partial nitritation/anammox (PN/A) and EBPR in a single reactor employing integrated fixed film activated sludge was tested. The reactor was fed with mainstream municipal wastewater (5.

Tailoring polyvinyl alcohol-sodium alginate (PVA-SA) hydrogel beads by controlling crosslinking pH and time.

Hydrogel-encapsulated catalysts are an attractive tool for low-cost intensification of (bio)-processes. Polyvinyl alcohol-sodium alginate hydrogels crosslinked with boric acid and post-cured with sulfate (PVA-SA-BS) have been applied in bioproduction and water treatment processes, but the low pH required for crosslinking may negatively affect biocatalyst functionality. Here, we investigate how crosslinking pH (3, 4, and 5) and time (1, 2, and 8 h) affect the physicochemical, elastic, and process properties of PVA-SA-BS beads.

Enhancing resource recovery via cranberry syrup waste at the Wisconsin Rapids WRRF: An experimental and modeling study.

The Wisconsin Rapids Wastewater Treatment Plant (WRWWTP) is faced with a more stringent effluent phosphorus requirement that will drive capital investment between 2020 and 2025. The facility will need to achieve a monthly average value of 0.36 mg L of total phosphorus (TP).

Impact of operational strategies on a sidestream enhanced biological phosphorus removal (S2EBPR) reactor in a carbon limited wastewater plant.

Water resource recovery facilities are faced with stringent effluent phosphorus limits to reduce nutrient pollution. Enhanced biological phosphorus removal (EBPR) is the most common biological route to remove phosphorus; however, many facilities struggle to achieve consistent performance due to limited carbon availability in the influent wastewater. A promising process to improve carbon availability is through return activated sludge (RAS) fermentation via sidestream EBPR (S2EBPR).

Effect of nitrous oxide (NO) on the structure and function of nitrogen-oxide reducing microbial communities.

Nitrous oxide (NO) is a potent greenhouse gas that can be produced by nitrifying and denitrifying bacteria. Yet the effects of NO on microbial communities is not well understood. We used batch tests to explore the effects of NO on mixed denitrifying communities.

Simultaneous nitrification-denitrification in biofilm systems for wastewater treatment: Key factors, potential routes, and engineered applications.

Simultaneous nitrification-denitrification (SND) is an advantageous bioprocess that allows the complete removal of ammonia nitrogen through sequential redox reactions leading to nitrogen gas production. SND can govern nitrogen removal in single-stage biofilm systems, such as the moving bed biofilm reactor and aerobic granular sludge system, as oxygen gradients allow the development of multilayered biofilms including nitrifying and denitrifying bacteria. Environmental and operational conditions can strongly influence SND performance, biofilm development and biochemical pathways.

Lab-scale data and microbial community structure suggest shortcut nitrogen removal as the predominant nitrogen removal mechanism in post-aerobic digestion (PAD).

Implementing an aerobic digestion step after anaerobic digestion, referred to as "post aerobic digestion" (PAD), can remove ammonia without the need for an external carbon source and destroy volatile solids. While this process has been documented at the lab-scale and full-scale, the mechanism for N removal and the corresponding microbial community that carries out this process have not been established. This research gap is important to fill because the nitrogen removal pathway has implications on aeration requirements and carbon demand, that is, short-cut N-removal requires less oxygen and carbon than simultaneous nitrification-denitrification.

Layered viscoelastic properties of granular biofilms.

Granular biofilms are dense spherical complex biological systems composed mainly of multi-microbial cells, water, and extracellular polymeric substances (EPS). They facilitate efficient purification and settling of activated sludge in wastewater treatment processes. The viscoelastic properties of these complex biofilm systems are important characteristics that control their growth and dictate how they respond to hydrodynamic forces and chemical stimuli.

Pushing the limits of solids retention time for enhanced biological phosphorus removal: process characteristics and Accumulibacter population structure.

Reducing the solids retention time (SRT) of the enhanced biological phosphorus removal (EBPR) process can increase organic carbon diversion to the sidestream for energy recovery, thereby realizing some of the benefits of the high rate activated sludge (HRAS) process. Determining the washout (i.e.

In situ groundwater remediation with bioelectrochemical systems: A critical review and future perspectives.

Groundwater contamination is an ever-growing environmental issue that has attracted much and undiminished attention for the past half century. Groundwater contamination may originate from both anthropogenic (e.g.

Towards mechanical characterization of granular biofilms by optical coherence elastography measurements of circumferential elastic waves.

Microbial granular biofilms are spherical, multi-layered aggregates composed of communities of bacterial cells encased in a complex matrix of hydrated extracellular polymeric substances (EPS). While granular aggregates are increasingly used for applications in industrial and municipal wastewater treatment, their underlying mechanical properties are poorly understood. The challenges of viscoelastic characterization for these structures are due to their spherical geometry, spatially heterogeneous properties, and their delicate nature.

Using kinetics and modeling to predict denitrification fluxes in elemental-sulfur-based biofilms.

Elemental sulfur (S ) can serve as an electron donor for water and wastewater denitrification, but few researchers have addressed the kinetics of S -based reduction of nitrate (NO ), nitrite (NO ), and nitrous oxide (N O). In addition, S -based denitrifying biofilms are counter-diffusional. This is because the electron donor (S ) is supplied from the biofilm attachment surface while the acceptor, for example, NO , is supplied from the bulk liquid.

Comammox Nitrospira are the dominant ammonia oxidizers in a mainstream low dissolved oxygen nitrification reactor.

Recent findings show that a subset of bacteria affiliated with Nitrospira, a genus known for its importance in nitrite oxidation for biological nutrient removal applications, are capable of complete ammonia oxidation (comammox) to nitrate. Early reports suggested that they were absent or present in low abundance in most activated sludge processes, and thus likely functionally irrelevant. Here we show the accumulation of comammox Nitrospira in a nitrifying sequencing batch reactor operated at low dissolved oxygen (DO) concentrations.

A Serial Biofiltration System for Effective Removal of Low-Concentration Nitrous Oxide in Oxic Gas Streams: Mathematical Modeling of Reactor Performance and Experimental Validation.

Wastewater treatment plants (WWTPs) are among the major anthropogenic sources of NO, a major greenhouse gas and ozone-depleting agent. We recently devised a zero-energy zero-carbon biofiltration system easily applicable to activated sludge-type WWTPs and performed lab-scale proof-of-concept experiments. The major drawback of the system was the diminished performance observed when fully oxic gas streams were treated.

Nondestructive characterization of soft materials and biofilms by measurement of guided elastic wave propagation using optical coherence elastography.

Biofilms are soft multicomponent biological materials composed of microbial communities attached to surfaces. Despite the crucial relevance of biofilms to diverse industrial, medical, and environmental applications, the mechanical properties of biofilms are understudied. Moreover, most of the available techniques for the characterization of biofilm mechanical properties are destructive.

Nitrous oxide emissions from biofilm processes for wastewater treatment.

This paper discusses the microbial basis and the latest research on nitrous oxide (NO) emissions from biofilms processes for wastewater treatment. Conditions that generally promote NO formation in biofilms include (1) low DO values, or spatial DO transitions from high to low within the biofilm; (2) DO fluctuations within biofilm due to varying bulk DO concentrations or varying substrate concentrations; (3) conditions with high reaction rates, which lead to greater formation of intermediates, e.g.

Mechanisms of nitrous oxide (N O) formation and reduction in denitrifying biofilms.

Nitrous oxide (N O) is a potent greenhouse gas that can be formed in wastewater treatment processes by ammonium oxidizing and denitrifying microorganisms. While N O emissions from suspended growth systems have been extensively studied, and some recent studies have addressed emissions from nitrifying biofilms, much less is known about N O emissions from denitrifying biofilm processes. This research used modeling to evaluate the mechanisms of N O formation and reduction in denitrifying biofilms.

Predicting NO emissions from nitrifying and denitrifying biofilms: a modeling study.

Wastewater treatment plants can be significant sources of nitrous oxide (NO), a potent greenhouse gas. While our understanding of NO emissions from suspended-growth processes has advanced significantly, less is known about emissions from biofilm processes. Biofilms may behave differently due to their substrate gradients and microbial stratification.

Kinetics of nitrous oxide (NO) formation and reduction by Paracoccus pantotrophus.

Nitrous oxide (NO) is a powerful greenhouse gas emitted from wastewater treatment, as well as natural systems, as a result of biological nitrification and denitrification. While denitrifying bacteria can be a significant source of NO, they can also reduce NO to N. More information on the kinetics of NO formation and reduction by denitrifying bacteria is needed to predict and quantify their impact on NO emissions.

Hydroxylamine diffusion can enhance N₂O emissions in nitrifying biofilms: a modeling study.

Wastewater treatment plants can be significant sources of nitrous oxide (N2O), a potent greenhouse gas. However, little is known about N2O emissions from biofilm processes. We adapted an existing suspended-growth mathematical model to explore N2O emissions from nitrifying biofilms.