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The two-stage anaerobic digestion (AD) for biohythane production is a sustainable solution, but it is sensitive to organic shock load that disrupts reactors and inhibits biohythane production. This study investigated biohythane production, reactor performance, and the possibility of post-failure restoration in a two-stage AD system designed for treating high-strength organic wastewater. Sudden shock load was applied by increasing the OLR threefold higher after reaching steady state phase. During shock load phase, hydrogen content, hydrogen yield and methane production rate (MPR) reached its peak values of 62.61 %, 1.641 mol H 2 /mol glucose, and 1.003 L CH 4 /L⋅d respectively before declining significantly. Interestingly, during the restorative phase, hydrogen production sharply declined to nearly zero, while methane production exhibited a resilience and reached its peak methane content of 52.2 %. The study successfully demonstrated the system's resilience to sudden shock load, ensuring stable methane production, while hydrogen production did not exhibit the same capability., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Pharmaceutical compounds are among the environmental contaminants that cause pollution of water resources and thereby threaten ecosystem services and the environmental health of the past decades. Antibiotics are categorized as emerging pollutants due to their persistence in the environment that are difficult to remove by conventional wastewater treatment. Ceftriaxone is one of the multiple antibiotics whose removal from wastewater has not been fully investigated. In this study, TiO 2 /MgO (5% MgO) the efficiency of photocatalyst nanoparticles in removing ceftriaxone was analyzed by XRD, FTIR, UV-Vis, BET, EDS, and FESEM. The results were compared with UVC, TiO 2 /UVC, and H 2 O 2 /UVC photolysis processes to evaluate the effectiveness of the selected methods. Based on these results, the highest removal efficiency of ceftriaxone from synthetic wastewater was 93.7% at the concentration of 400 mg/L using TiO 2 /MgO nano photocatalyst with an HRT of 120 min. This study confirmed that TiO 2 /MgO photocatalyst nanoparticles efficiently removed ceftriaxone from wastewater. Future studies should focus on the optimization of reactor conditions and improvements of the reactor design to obtain higher removal of ceftriaxone from wastewater., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Recently, graphitic carbon nitride (g-C 3 N 4 ) has received significant attention as a non-metallic, visible-light-activated photocatalyst for treating water and wastewater by degrading contaminants. Accordingly, previous review articles have focused on the photocatalytic properties of g-C 3 N 4 -based materials. However, g-C 3 N 4 has several other notable features, such as high adsorption affinity towards aromatic substances and heavy metals, high thermal and chemical resistances, good compatibility with various materials, and easily scalable synthesis; therefore, in addition to simple photocatalysis, it can be widely used in other decontamination systems based on activation of oxidants and electrocatalysis. This critical review provides a comprehensive summary of recent advancements in g-C 3 N 4 -based materials and their use in treating polluted water and wastewater via the following routes (1) activation of oxidizing agents (e.g., hydrogen peroxide, ozone, peroxymonosulfate, and persulfate): and (2) photoelectrocatalysis using fabricated g-C 3 N 4 -based photocathodes and photoanodes. For each route, we briefly summarize the primary mechanisms, distinctive features, and performances of various water treatment systems using g-C 3 N 4 -based catalysts. We also highlight the specific roles of g-C 3 N 4 in improving the efficiencies of these treatment processes. The advantages and limitations of previously reported water treatment systems using g-C 3 N 4 -based materials are also described and compared in this review. Finally, we discuss the challenges and prospects of improving g-C 3 N 4 -based water purification applications., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Wastewater reuse is considered one of the most promising practices for the achievement of sustainable water management on a global scale. In the context of the safe reuse of water, membrane filtration is a competitive technique due to its superior efficiency in several processes. However, membrane fouling by organics is an inevitable challenge that is encountered during the practical application of membrane processes. The resolution of the membrane fouling challenge requires an in-depth understanding of many complex interactions between organic foulants and the membrane. In the last few decades, the forward osmosis (FO) membrane process, which exploits osmosis as a driving force, has emerged as an effective technology for water production with low energy consumption, thus leveraging the water-energy nexus. However, their successful application is severely hampered by membrane fouling, which is caused by such complex fouling mechanisms as cake enhanced osmotic pressure (CEOP), reverse salt diffusion (RSD), internal, and external concentration polarization as well as by the traditional fouling processes encompassing colloids, microbial (biofouling), inorganic, and organic fouling. Of these fouling types, the fouling potential of organic matter in FO has not been given sufficient attention, in particular, when FO is applied to wastewater treatment. This paper aims to provide a comprehensive overview of FO membrane fouling for wastewater applications with a special focus on the identification of the major factors that lead to the unique properties of organic fouling in this filtration process. Based on the critical assessment of organic fouling formation and the governing mechanisms, proposals were advanced for future research aimed at the mitigation of FO membrane fouling to enhance process efficiency in wastewater applications., (Copyright © 2019 The Authors. Published by Elsevier Ltd.. All rights reserved.)

The gas-liquid partitioning behavior of major odorants (acetic acid, propionic acid, isobutyric acid, n-butyric acid, i-valeric acid, n-valeric acid, hexanoic acid, phenol, p-cresol, indole, skatole, and toluene (as a reference)) commonly found in microbially digested wastewaters was investigated by two experimental approaches. Firstly, a simple vaporization method was applied to measure the target odorants dissolved in liquid samples with the aid of sorbent tube/thermal desorption/gas chromatography/mass spectrometry. As an alternative method, an impinger-based dynamic headspace sampling method was also explored to measure the partitioning of target odorants between the gas and liquid phases with the same detection system. The relative extraction efficiency (in percent) of the odorants by dynamic headspace sampling was estimated against the calibration results derived by the vaporization method. Finally, the concentrations of the major odorants in real digested wastewater samples were also analyzed using both analytical approaches. Through a parallel application of the two experimental methods, we intended to develop an experimental approach to be able to assess the liquid-to-gas phase partitioning behavior of major odorants in a complex wastewater system. The relative sensitivity of the two methods expressed in terms of response factor ratios (RFvap/RFimp) of liquid standard calibration between vaporization and impinger-based calibrations varied widely from 981 (skatole) to 6,022 (acetic acid). Comparison of this relative sensitivity thus highlights the rather low extraction efficiency of the highly soluble and more acidic odorants from wastewater samples in dynamic headspace sampling.

This study aims to investigate the effect of operational conditions on organic fouling occurring in a direct contact membrane distillation (DCMD) system used to treat wastewater. A mixed solution of sodium alginate (SA) and bovine serum albumin (BSA) was used as a feed solution to simulate polysaccharides and proteins, respectively, assumed as the main organic foulants. The permeate flux was observed at two feed temperatures 35 and 50 °C, as well as three feed solution pH 4, 6, and 8. Higher permeate flux was observed for higher feed temperature, which allows higher vapor pressure. At higher pH, a smaller particle size was detected with lower permeate flux. A mathematical model based on mass balance was developed to simulate permeate flux with time by assuming (i) the cake formation controlled by attachment and detachment of foulant materials and (ii) the increase in specific cake resistance, the function of the cake porosity, as the main mechanisms controlling membrane fouling to investigate the fouling mechanism responsible of permeate flux decline. The model fitted well with the experimental data with R2 superior to 0.9. High specific cake resistance fostered by small particle size would be responsible for the low permeate flux observed at pH 8. [ABSTRACT FROM AUTHOR]

• Membrane distillation is a thermally-driven membrane separation process. • MD performance varies greatly depending upon intrinsic properties of materials. • Membrane materials is one of the key features to improve MD performance. • Membrane fouling and wetting needs to be overcome with novel MD materials. • MD process can be considered as a post-treatment in wastewater treatment and reuse. Membrane distillation (MD) is a thermally driven membrane separation process in which only vapor molecules can be transferred through hydrophobic membrane. Significant efforts have been made with MD membrane especially for seawater desalination, but its application is expanded quickly for wastewater treatment and reuse. Membrane performance in MD process varies strongly depending upon the intrinsic properties of membrane materials. This paper provides critical reviews on MD membrane focusing on fabrication methods and membrane materials as well as its applications for wastewater treatment and reuse. To achieve high effluent quality for wastewater reuse purposes, the MD process is integrated with membrane bioreactor (MBR) although both organic and inorganic fouling are the main issues to be resolved in hybrid MD system. [ABSTRACT FROM AUTHOR]

Abstract This study aims to develop a mathematical model to estimate the initial permeate flux of a direct contact membrane distillation process operated with various solids concentrations and Cross Flow Velocities (CFVs). Digestate produced from an anaerobic digestion of livestock wastewater was used as a feed solution for the laboratory scale membrane distillation. Heat transfer coefficients and Nusselt number constants were determined from the distillation experiments performed with various CFVs and feed solution temperatures. An empirical function was derived to reflect the effect of solids concentration on the flux prediction. A statistical analysis supported that the flux predicted by the model fitted very well with the observed flux. By using the developed model, numerical experiments were performed to simulate the flux according to various CFVs, feed solution temperatures, and solids concentrations (0–2200 mg/L). Also, Temperature Polarization Coefficient (TPC) values were calculated by using the results simulated from the numerical experiments. The developed model can be used to predict the initial flux of the membrane distillation process specifically to treat wastewater including high solids contents, and the modeling works can provide more insights on the relationship among flux, CFV, temperature difference, solids concentrations, and heat transfer efficiency. Graphical abstract fx1 Highlights • A mathematical model developed to predict the permeate flux of the DCMD process. • Suspended solids had more significant influence on the flux than dissolved solids. • Flux with suspended solids concentration was suggested as J = B { P f 0 (1 − a C ss ) − P p 0 }. • Modeling provided more understandings on the membrane distillation process. [ABSTRACT FROM AUTHOR]

Highlights: [•] Gas chromatography direct injection (GC-DI) is used commonly to quantify VFAs in waste water. [•] The extent of uncertainties in the GC-DI based analysis of VFA has scarcely been evaluated. [•] The pattern of bias in GC-DI analysis of VFA is evaluated against a more reliable TD method. [ABSTRACT FROM AUTHOR]