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Research on the use of peracetic acid (PAA) activated by nonmetal solid catalysts for the removal of dissolved refractory organic compounds has gained attention recently due to its improved efficiency and suitability for advanced water treatment (AWT). Among these catalysts, nanocarbon (NC) stands out as an exceptional example. In the NC-based peroxide AWT studies, the focus on the mechanism involving multimedia coordination on the NC surface (reactive species (RS) path, electron reduction non-RS pathway, and singlet oxygen non-RS path) has been confined to the one-step electron reaction, leaving the mechanisms of multichannel or continuous electron transfer paths unexplored. Moreover, there are very few studies that have identified the nonfree radical pathway initiated by electron transfer within PAA AWT. In this study, the complete decomposition (kobs = 0.1995) and significant defluorination of perfluorooctanoic acid (PFOA, deF% = 72%) through PAA/NC has been confirmed. Through the use of multiple electrochemical monitors and the exploration of current diffusion effects, the process of electron reception and conduction stimulated by PAA activation was examined, leading to the discovery of the dynamic process from the PAA molecule → NC solid surface → target object. The vital role of prehydrated electrons (epre–) before the entry of resolvable electrons into the aqueous phase was also detailed. To the best of our knowledge, this is the first instance of identifying the nonradical mechanism of continuous electron transfer in PAA-based AWT, which deviates from the previously identified mechanisms of singlet oxygen, single-electron, or double-electron single-path transfer. The pathway, along with the strong reducibility of epre– initiated by this pathway, has been proven to be essential in reducing the need for catalysts and chemicals in AWT.
Intensifying Anaerobic Digestion with a Side-Stream Vacuum-Based Biosolids Treatment Technology: Process Validation Exceeding ExpectationsAbstractThis study evaluates the application of a novel ex-situ vacuum-enhanced anaerobic digestion technology, referred to as IntensiCarbTM (IC), for process intensification through decoupling SRT from HRT, and ammonia recovery. Findings revealed that the IC sustain almost the same methane yield and COD destruction efficiency as the control at three times the organic loading rate (OLR). Furthermore, the ammonia concentration in IC- digester operating at 3 times higher organic loading was pretty much the same as the control, demonstrating the effectiveness of IC-technology in elutriating a large fraction of ammonia from IC-digester into the condensate. This leads to stable digester operation as well as a potential to generate revenue. The combination of high organic loading and low ammonia concentrations resulted in the prevalence of the higher growth rate Methanosarcinaceae in the IC-digester compared to the low growth rate Methanoseata predominance in the control.A novel ex-situ vacuum-enhanced anaerobic digestion technology was evaluated for process intensification in anaerobic digesters. This technology, referred to as IntensiCarbTM (IC), could increase the OLR and volumetric loading by 3 times while maintaining stable methane yields and COD destruction. Ammonia recovery, reduced digester size, as well as reduced nitrogen loadings in sidestreams, are the major advantage of IC-technology.SpeakerKhadir, AliPresentation time13:30:0013:50:00Session time13:30:0015:00:00SessionAdvances in Anaerobic Digestion and Sidestream TreatmentSession locationRoom S404a - Level 4TopicIntermediate LevelTopicIntermediate LevelAuthor(s)Khadir, AliAuthor(s)A. Khadir 1; F. Omoye 2 ; E. Jang 3; D. Santoro 4; J. Walton 4; C. Muller 5; A. Al-Omari 6; K. Bell 7; G. Nakhla 8;Author affiliation(s)Western University, Canada 1; Western University, Canada 2 ; USP Technologies, Canada 3; USP Technologies, Canada 4; USP Technologies, Canada 4; Brown and Caldwell, USA 5; Brown and Caldwell, USA 6; Brown and Caldwell 7; Western University, Canada 8;SourceProceedings of the Water Environment FederationDocument typeConference PaperPublisherWater Environment FederationPrint publication date Oct 2023DOI10.2175/193864718825158983Volume / Issue Content sourceWEFTECCopyright2023Word count15
Abstract This paper includes survey results from 17 full‐scale water resource recovery facilities (WRRFs) to explore their technical, operational, maintenance, and management‐related challenges during COVID‐19. Based on the survey results, limited monitoring and maintenance of instrumentation and sensors are among the critical factors during the pandemic which resulted in poor data quality in several WRRFs. Due to lockdown of cities and countries, most of the facilities observed interruptions of chemical supply frequency which impacted the treatment process involving chemical additions. Some plants observed influent flow reduction and illicit discharges from industrial wastewater which eventually affected the biological treatment processes. Delays in equipment maintenance also increased the operational and maintenance cost. Most of the plants reported that new set of personnel management rules during pandemic created difficulties in scheduling operator's shifts which directly hampered the plant operations. All the plant operators mentioned that automation, instrumentation, and sensor applications could help plant operations more efficiently while working remotely during pandemic. To handle emergency circumstances including pandemic, this paper also highlights resources and critical factors for emergency responses, preparedness, resiliency, and mitigation that can be adopted by WRRFs.
Rotating belt filtration (RBF) is a technology designed for the removal of suspended solids, and effluent organic matter from wastewater that has been recently undergoing intensive development and testing. Generally, RBF can remove solids to meet Ten State Standards (‘Primary settling of normal domestic wastewater can be expected to remove approximately one-third of the influent BOD5 when operating at an overflow rate of 41 m3/(m2 d) [1,000 gallons per day/square foot]’) and European council directive standards (at least 50% total suspended solids (TSS) and 20% Biological Oxygen Demand (BOD) removal). Recent testing have also shown that, when a polymer is added upstream of the RBF, solids and organics removal is significantly enhanced. Advantages of RBF include reduced space requirement, ability to support small mesh without clogging, reduced civil engineering site work, and modular construction allowing for reduced design work, faster installation, and ease of plant expansion. Additional site-specific advantages may include reduced capital and operation costs, and energy savings (e.g. reduced aeration costs following the addition of primary solids removal by RBF against the baseline case where primary solids removal is not practiced). As a matter of fact, when RBF is operated as a pretreatment to remove 50% of the incoming TSS prior to the biological aerated tank, a significant decrease in power consumption ranging from 22 to 28% can be expected if compared to the case where no primary treatment is used. This paper focuses on the current status of development of the technology and provides a literature review of recent experimental studies focused on testing RBF.
Wastewater disinfection processes are typically designed according to heuristics derived from batch experiments in which the interaction among wastewater quality, reactor hydraulics, and inactivation kinetics is often neglected. In this paper, a computational fluid dynamics (CFD) study was conducted in a nondeterministic (ND) modeling framework to predict the Escherichia coli inactivation by peracetic acid (PAA) in municipal contact tanks fed by secondary settled wastewater effluent. The extent and variability associated with the observed inactivation kinetics were both satisfactorily predicted by the stochastic inactivation model at a 95% confidence level. Moreover, it was found that (a) the process variability induced by reactor hydraulics is negligible when compared to the one caused by inactivation kinetics, (b) the PAA dose required for meeting regulations is dictated equally by the fixed limit of the microbial concentration as well as its probability of occurrence, and (c) neglecting the probability of occurrence during process sizing could lead to an underestimation of the PAA dose required by as much as 100%. Finally, the ND-CFD model was used to generate sizing information in the form of probabilistic disinfection curves relating E. coli inactivation and probability of occurrence with the average PAA dose and PAA residual concentration at the outlet of the contact tank.
This book introduces the 3R concept applied to wastewater treatment and resource recovery under a double perspective. Firstly, it deals with Innovative technologies leading to: Reducing energy requirements, space and impacts; Reusing water and sludge of sufficient quality; and Recovering resources such as energy, nutrients, metals and chemicals, including biopolymers. Besides targeting effective C,N&P removal, other issues such as organic micropollutants, gases and odours emissions are considered. Most of the technologies analysed have been tested at pilot- or at full-scale. Tools and methods for their Economic, Environmental, Legal and Social impact assessment are described.The 3R concept is also applied to Innovative Processes design, considering different levels of innovation: Retrofitting, where novel units are included in more conventional processes; Re-Thinking, which implies a substantial flowsheet modification; and Re-Imagining, with completely new conceptions. Tools are presented for Modelling, Optimising and Selecting the most suitable plant layout for each particular scenario from a holistic technical, economic and environmental point of view.ISBN: 9781780407869 (Paperback)ISBN: 9781780407876 (eBook)
It is generally thought that antibiotics confer upon the producing bacteria the ability to inhibit or kill neighboring microorganisms, thereby providing the producer with a significant competitive advantage. Were this to be the case, the concentrations of emitted antibiotics in the vicinity of producing bacteria might be expected to fall within the ranges of MICs that are documented for a number of bacteria. Furthermore, antibiotic concentrations that bacteria are punctually or chronically exposed to in environments harboring antibiotic-producing bacteria might fall within the range of minimum selective concentrations (MSCs) that confer a fitness advantage to bacteria carrying acquired antibiotic resistance genes. There are, to our knowledge, no available in situ measured antibiotic concentrations in the biofilm environments that bacteria typically live in. The objective of the present study was to use a modeling approach to estimate the antibiotic concentrations that might accumulate in the vicinity of bacteria that are producing an antibiotic. Fick's law was used to model antibiotic diffusion using a series of key assumptions. The concentrations of antibiotics within a few microns of single producing cells could not reach MSC (8 to 16 μg/L) or MIC (500 μg/L) values, whereas the concentrations around aggregates of a thousand cells could reach these concentrations. The model outputs suggest that single cells could not produce an antibiotic at a rate sufficient to achieve a bioactive concentration in the vicinity, whereas a group of cells, each producing the antibiotic, could do so. IMPORTANCE It is generally assumed that a natural function of antibiotics is to provide their producers with a competitive advantage. If this were the case, sensitive organisms in proximity to producers would be exposed to inhibitory concentrations. The widespread detection of antibiotic resistance genes in pristine environments suggests that bacteria are indeed exposed to inhibitory antibiotic concentrations in the natural world. Here, a model using Fick's law was used to estimate potential antibiotic concentrations in the space surrounding producing cells at the micron scale. Key assumptions were that per-cell production rates drawn from the pharmaceutical manufacturing industry are applicable in situ, that production rates were constant, and that produced antibiotics are stable. The model outputs indicate that antibiotic concentrations in proximity to aggregates of a thousand cells can indeed be in the minimum inhibitory or minimum selective concentration range.
Summary Nuclear magnetic resonance (NMR) microscopy is a completely noninvasive technique that can be used to acquire images with high spatial resolution through opaque objects such as plant organs and tissue parts. The image contrast can be chosen to represent the anatomical details or to visualize the spatial distribution of a range of physico‐chemical parameters such as the apparent diffusion constant of water or the velocity of water flow within plants in vivo . In addition, images can be generated which show the spatial distribution of metabolites. Furthermore, it is possible to detect chemical compounds labelled with the stable isotope 13 C and to generate images showing the spatial distribution of the 13 C label in the intact plant. The ability to monitor water flow and transport of 13 C‐labelled tracer in intact plants with NMR microscopy favours the use of this technique in the investigation of long‐distance transport processes in plants. A short introduction into the technical principles of NMR microscopy is provided and the problems associated with applications to plants are summarized. The potential of the technique is explained with applications to Zinnia elegans plants, wheat grains and Brassica napus siliques.
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