Release Of Contaminants Research Articles

Algorithm for steady contaminant distribution in ventilation systems with air recirculation: Contaminant release in ventilation ducts

When contaminants are released naturally or deliberately in ventilation ducts, they can contaminate the supply air and rooms through the return air recirculation of the ventilation and air conditioning system. Few studies have considered the impact of contaminant transport through air recirculation on the non-uniform indoor contaminant distribution. In this study, a method for calculating the steady-state contaminant distribution in a ventilation system with air recirculation when there is a contaminant release from the ventilation duct is presented. The ventilation ducts are considered as a virtual room and modelled separately from the rooms, both using linear superposition expressions based on accessibility indicators to obtain a relationship between contaminant concentrations at the outlet and inlet. A total of four sub-methods are proposed considering different treatments for the return and supply air ducts connected to each air handling unit (AHU). The proposed methods (Methods 1–3) considering the non-uniform characteristics of the ducts are shown to have an accuracy comparable to that of CFD (computational fluid dynamics) simulations, with an average prediction deviation of less than 5%, whereas the use of well-mixed assumption in the ducts (Method 4) results in an average prediction deviation of up to 45% in one of the rooms when the contaminant source is close to the diversion position of the supply air duct. The proposed method avoids the need for holistic modelling and iterative simulation of complex ventilation and air-conditioning system and multiple rooms, and allows for rapid prediction of contaminant distribution.

An enhanced fourier neural operator surrogate for radioactive plume transport forecasting

Accurate real-time forecasts of atmospheric plume behavior are crucial for effective management of environmental release incidents. However, the computational demands of weather simulations and particle transport codes limit their applicability during emergencies. In this study, we employ a U-Net enhanced Fourier Neural Operator (U-FNO) to statistically emulate the calculations of the WSPEEDI dose forecasting numerical simulator, using pre-calculated ensemble simulations. The developed emulator is capable of effectively simulating any radioactive-release scenario and generating the time series of dose distribution in the environment 4000 times faster than the numerical simulator, while still maintaining high accuracy. It predicts the plume direction, extent, and dose-rate magnitudes using initial- and boundary-condition meteorological data as input. The speed and efficiency of this framework offers a powerful tool for swift decision-making during emergencies, facilitating risk-informed protective actions, evacuation execution, and zone delineation. Its application extends to various contaminant release and transport problems, and can be instrumental in engineering tasks requiring uncertainty quantification (UQ) for environmental risk assessment.

Ventilation performance evaluation of an operating room with temperature-controlled airflow system in contaminant control: A numerical study

This article investigates the efficacy of temperature-controlled airflow systems in modern operating rooms for contaminant control, a critical factor in preventing surgical site infections. We have conducted experimental measurements in an operating room equipped with temperature-controlled ventilation to map the airflow field and contaminant dispersion (airborne particles with diameters ranging from 0.5 to 1 μm). The results were used to validate the computational fluid dynamics code, which was then employed to simulate and examine different conditions, including contaminant release locations and air supply rates. Realizable k-epsilon and passive scalar models were utilized to simulate airflow and airborne particle phases. We assessed the airflow distribution and contaminant dispersion, utilizing indices such as ventilation and air change efficiency scales. The analysis provided quantitative insights into the distribution and removal of contaminants, as well as the speed at which the room air was replaced. Contamination was found to be effectively reduced when contaminants were released near exhaust outlets or under central unidirectional inlets. The presence of the operating table caused a big distortion of the central downward airflow, forming a horizontal air barrier at the periphery. Under this unique interior configuration, an appropriate air supply ratio between central and periphery zones was required to achieve optimal overall ventilation performance.

Groundwater, salt and contaminant transport in a coastal aquifer system with a low‐permeability layer in the intertidal zone

AbstractLow‐permeability layer (LPL), formed by natural deposit or artificial reclamation and commonly found below the intertidal zone of coastal groundwater system, can retard the ingress of seawater and contaminants, and shorten the travel time of the land‐sourced contaminant to the marine environment compared with a homogenous sandy coastal aquifer. However, there is limited understanding on how an intertidal LPL, a condition occurred in a coastal aquifer at Moreton Bay, Australia, influences the groundwater and contaminant transport across the shallow beach aquifer system. We characterized the aquifer hydrological parameters, monitored the in situ groundwater heads, and constructed a 2‐D numerical model to analyses the cross‐shore hydrological processes in this stratified system. The calibrated model suggests that in the lower aquifer, the inland‐source fresh groundwater flowed horizontally towards the sea, upwelled along the freshwater–saltwater interface, and exited the aquifer at the shore below the LPL. Whereas in the upper aquifer, the tidally driven seawater circulation formed a barrier that prevented fresh groundwater from horizontal transport and discharge to the beach above the LPL, thereby directing its leakage to the lower aquifer. A contaminant represented by a conservative tracer was ‘released’ the upper aquifer in the model and results showed that the spreading extent of the contaminant plume, the maximum rate of contaminant discharge to the ocean, and its plume length decreased compared with a simulation case in a homogenous sandy aquifer. Sensitivity analysis was also conducted to investigate the characteristics of the LPL, including its continuity and hydraulic conductivity, which were found to vary along the beach at Moreton Bay. The result shows that with a lower hydraulic conductivity and continuous layer of LPL reduced the groundwater exchange and contaminant transport between upper and lower aquifer. The findings from the combined field and modelling investigations on the impact of an intertidal LPL on coastal aquifer systems highlight its significant implications to alter the groundwater and mass transport across the land–ocean interface.

Factors Influencing Microbial Contamination of Groundwater: A Systematic Review of Field-Scale Studies.

Pathogenic microorganisms released onto the soil from point or diffuse sources represent a public health concern. They can be transported by rainwater that infiltrates into subsoil and reach the groundwater where they can survive for a long time and contaminate drinking water sources. As part of the SCA.Re.S. (Evaluation of Health Risk Related to the Discharge of Wastewater on the Soil) project, we reviewed a selection of field-scale studies that investigated the factors that influenced the fate of microorganisms that were transported from the ground surface to the groundwater. A total of 24 studies published between 2003 and 2022 were included in the review. These studies were selected from the PubMed and Web of Science databases. Microbial contamination of groundwater depends on complex interactions between human activities responsible for the release of contaminants onto the soil, and a range of environmental and biological factors, including the geological, hydraulic, and moisture characteristics of the media traversed by the water, and the characteristics and the viability of the microorganisms, which in turn depend on the environmental conditions and presence of predatory species. Enterococci appeared to be more resistant in the underground environment than thermotolerant coliforms and were suggested as a better indicator for detecting microbial contamination of groundwater.

Bioaccumulation of carcinogenic metals in river fish: A quantitative investigation of public health risk

The rivers are severely contaminated by human activities due to its massive outflow and industrial effluents. Three economically significant fish species Sperata seenghala, Wallago attu, and Cyprinus carpio from the river water were selected for the assessment of heavy metals (HMs). The edible part of the collected fish from the river sampling sites were analyzed to determine the metal concentrations and potential health risks to humans. The Atomic Absorption Spectroscopy (AAS) technique was used to measure HMs including lead (Pb), chromium (Cr), and copper (Cu) for both water and fish samples. Order of HMs in the fish was found as Pb > Cd > Cr. Levels of HMs in all species were found higher than the European Commission (EC) recommended acceptable levels. The metal pollution index (MPI) indicates that W. attu and S. seenghala, two highly consumed fish species, have accumulated HMs in higher concentrations. Wallago attu has the highest bioaccumulation factor (BAF) for both Pb and Cd permissible levels. For adult and children, the Hazard Index (HI) and Targeted Hazard Quotient (THQ) values were less than 1, which indicated that there would be no non-carcinogenic health consequences. Carcinogenic risk (CR) exposure to Pb, Cd, and Cr for all consumers was found to be higher than the permitted limit (10−6-10−4), while children were found more vulnerable than adults in terms of CR values. The study findings identified several sources of contaminants in the area, including agricultural waste, lubricant usage, and electroplating material production dumping near into the river water. Based on the results of the analysis, metal concentrations exceeded the thresholds for carcinogenic health risks, indicating that fish from the area are generally unsafe to consume. Therefore, immediate action must be taken to reduce or prevent the discharge of contaminants into the river. Additionally, regular monitoring of the river's water quality should be conducted to control the contamination of water.

Non-target screening to track contaminant removal and release during nature-based water treatment

Non-target screening to track contaminant removal and release during nature-based water treatment

HydroFATE (v1): a high-resolution contaminant fate model for the global river system

Abstract. Pharmaceuticals and household chemicals are neither fully consumed nor fully metabolized when routinely used by humans, thereby resulting in the emission of residues down household drains and into wastewater collection systems. Since treatment systems cannot entirely remove these substances from wastewaters, the contaminants from many households connected to sewer systems are continually released into surface waters. Furthermore, diffuse contributions of wastewaters from populations that are not connected to treatment systems can directly (i.e., through surface runoff) or indirectly (i.e., through soils and groundwater) contribute to contaminant concentrations in rivers and lakes. The unplanned and unmonitored release of such contaminants can pose important risks to aquatic ecosystems and ultimately human health. In this work, the contaminant fate model HydroFATE is presented, which is designed to estimate the surface-water concentrations of domestically used substances for virtually any river in the world. The emission of compounds is calculated based on per capita consumption rates and population density. A global database of wastewater treatment plants is used to separate the effluent pathways from populations into treated and untreated and to incorporate the contaminant pathways into the river network. The transport in the river system is simulated while accounting for processes of environmental decay in streams and in lakes. To serve as a preliminary performance evaluation and proof of concept of the model, the antibiotic sulfamethoxazole (SMX) was chosen, due to its widespread use and the availability of input and validation data. The comparison of modelled concentrations against a compilation of reported SMX measurements in surface waters revealed reasonable results despite inherent model uncertainties. A total of 409 000 km of rivers were predicted to have SMX concentrations that exceed environmental risk thresholds. Given the high spatial resolution of predictions, HydroFATE is particularly useful as a screening tool to identify areas of potentially elevated contaminant exposure and to guide where local monitoring and mitigation strategies should be prioritized.

The Effect of Zinc Concentration on Bioaccumulation in Milkfish <i>(Chanos chanos)</i> Use of <sup>65</sup>Zn as a Radioactive Tracer

Bioaccumulation studies of zinc (Zn) in milkfish (Chanos chanos) have been carried out in the laboratory using a 65Zn radiotracer. The research was conducted to determine the effect of Zn concentration on the ability of Chanos chanos to accumulate and release these contaminants. Zn absorption follows the single-compartment model, and experiments were carried out until stable conditions were achieved. The stages of research were biota collection, acclimatization, bioaccumulation, and elimination. Acclimatization was carried out for biota adaptation in the experimental environment. Bioaccumulation was carried out for 7 days by placing the biota in an aquarium filled with seawater added with 65Zn radiotracer contaminants. The elimination process involves the release of contaminants from the biota by placing them in contaminant-free seawater for 7 days. The results of the bioaccumulation experiment showed that the concentration factor (CF) ranged from 0.67 - 18.18 mLgr-1 at a concentration of ZnCl2 of 1.5 ppm, and the absorption constant (ku) 1.878 - 3.267d-1 and R2 was 0.0276. The release of contaminants in depuration experiments was highest at ZnCl2 2 ppm concentrations. The percentage of retention during depuration was between 14.61 - 79.91 %, the elimination constant (ke) was 8.681, and R2 was 0.7213.

Long‐term evaluation of hydrocarbon degradation rates within the source zone under natural and enhanced attenuation for site closure purposes

AbstractDespite addressing the cleanup of petroleum hydrocarbon contamination plumes in groundwater, challenges with site closure persist due to the ongoing long‐term contaminant release from source zones. Thus, source zone monitoring even in the presence of residual light nonaqueous‐phase liquid (LNAPL) is mandated by many countries' regulatory agencies before site closure. In this study, four independent controlled‐release sites, each containing a particular fraction of ethanol in gasoline, that is, 10%, 24%, 25%, and 85% (v/v), were subjected to monitored natural attenuation (MNA) alone (E24 and E85), and with nitrate (E25) and sulfate (E10) biostimulation at the vicinity of the source zone. To the best of the authors' knowledge, this is the longest controlled gasohol release monitoring study performed to date at the source zone for site closure (nearly 18 years of monitoring). Both natural source zone depletion and biostimulation were found to reduce benzene concentrations to acceptable remediation target levels according to environmental regulatory councils. Benzene biodegradation rates (λs) were one order of magnitude higher than those reported in the literature for diluted concentrations in groundwater plumes. The decay rate of benzene varied between 0.45 and 1.75/year and was strongly influenced by the mass of ethanol. Compared to biostimulation with nitrate (half‐life of 1.52 years), MNA alone resulted in faster benzene removal rates (half‐life of 0.96 years). Anaerobic biostimulation with sulfate had negligible effects on benzene, toluene, ethylbenzene, and xylene (o‐, m‐, and p‐xylene [BTEX]) biodegradation compared to natural attenuation alone. The highest ethanol concentration (E85) led to faster benzene removal (with a half‐life of 0.40 years), which was even higher than MNA under lower ethanol concentrations (E24). Benzene half‐life was 2.2‐fold slower in the site with the lowest ethanol (E10) compared to E85, indicating that the negative effects of ethanol on BTEX biodegradation appeared to be short‐lived and may need to be re‐evaluated over the long term. Benzene decay rates were approximately six times slower in the source zone than the rates obtained for groundwater plumes, emphasizing the importance of targeting the LNAPL after plume retreat. The study's findings can assist practitioners in better predicting the lines of evidence for BTEX bioremediation and remediation cleanup times at a lower cost in the presence of ethanol, as well as providing guidance for determining whether biostimulation is necessary to expedite source zone remediation for site closure.

Determination of potentially toxic elements bioaccumulated in the commercially important pelagic fish narrow-barred Spanish mackerel (Scomberomorus commerson)

Anthropogenic activities have increased the discharge of marine contaminants threatening marine life. Small gulfs, such as the Arabian Gulf, are vulnerable to accumulating potentially toxic elements in marine species due to slow water exchange. The concentration of 21 elements was determined in the tissues of Scomberomorus commerson from Umm Al Quwain (United Arab Emirates) and Bandar Abbas (Iran). Chromium, Copper, and Iron exceeded internationally established maximum permissible limits. Sites could not be distinguished based on Principle Component Analyses of elements. Elevated Cu and Cr in muscle are of concern to marine species as well as humans. Metal Pollution Index showed a significant difference between sites, with 20.34 % and 100 % of individuals suffering high metal toxicity and poor body conditions, respectively. The Arabian Gulf is experiencing an increase in discharge of industrial wastes. Implementation of strict policies to reduce discharge of toxic substances is required to protect marine organisms and humans.

Mono and polycyclic aromatic hydrocarbons in waterpipe wastewater: Level and ecotoxicological risk assessment

Increasing of tobacco consumption around the world has led to the production of a large volume of waterpipe wastewater that enter the environment (e.g., coastal areas)and threaten aquatic creatures. However, until now, no research has been carried out on the amounts of monocyclic and polycyclic aromatic hydrocarbons (PAHs) in hookah wastewater. In the current study, the levels of PAHs and BTEX compounds in waterpipe wastewater resulting from the use of different tobacco brands were determined and their eco-toxicological effects were also evaluated. The mean levels of ƩPAHs in waterpipe wastewater of Al Tawareg, Al-Fakher, Nakhla, Tangiers and traditional tobacco brands samples were 3.48 ± 1.65, 3.33 ± 1.52, 3.08 ± 1.25, 2.41 ± 0.87 and 0.70 ± 0.13 μg/L, respectively. The mean levels of ƩBTEX in waterpipe wastewater of Al Tawareg, Al-Fakher, Nakhla, Tangiers and traditional tobacco brands samples were also 2.53 ± 0.61, 2.65 ± 0.78, 2.51 ± 0.72, 2.35 ± 0.56, and 0.78 ± 0.12 μg/L, respectively. The maximum level of PAHs and BTEX compounds in all brands/flavors samples were for naphthalene (Naph) and toluene, respectively. The concentrations of some PAHs (fluoranthene (Flrt), anthracene (Ant), benzo(b)fluoranthene (BbF), benzo(b)fluoranthene (BkF), benzo (g,h,i)perylene (BghiP) and dibenzo (a, h) anthracene (DahA)) and BTEX compounds (benzene) in the waterpipe wastewater samples were more than recommended guidelines and standards by the international reputable organizations such as World Health Organization (WHO) for water quality. Waterpipe wastewater can be introduced as an important origin for the release of these dangerous contaminants into the environmental matrixes. Therefore, more stringent regulations should be considered for the safe disposal of such hazardous wastes including waterpipe wastewater.

Progress in the Elimination of Organic Contaminants in Wastewater by Activation Persulfate over Iron-Based Metal-Organic Frameworks.

The release of organic contaminants has grown to be a major environmental concern and a threat to the ecology of water bodies. Persulfate-based Advanced Oxidation Technology (PAOT) is effective at eliminating hazardous pollutants and has an extensive spectrum of applications. Iron-based metal-organic frameworks (Fe-MOFs) and their derivatives have exhibited great advantages in activating persulfate for wastewater treatment. In this article, we provide a comprehensive review of recent research progress on the significant potential of Fe-MOFs for removing antibiotics, organic dyes, phenols, and other contaminants from aqueous environments. Firstly, multiple approaches for preparing Fe-MOFs, including the MIL and ZIF series were introduced. Subsequently, removal performance of pollutants such as antibiotics of sulfonamides and tetracyclines (TC), organic dyes of rhodamine B (RhB) and acid orange 7 (AO7), phenols of phenol and bisphenol A (BPA) by various Fe-MOFs was compared. Finally, different degradation mechanisms, encompassing free radical degradation pathways and non-free radical degradation pathways were elucidated. This review explores the synthesis methods of Fe-MOFs and their application in removing organic pollutants from water bodies, providing insights for further refining the preparation of Fe-MOFs.

Effect of an innovative sorbent material coupled to continuous flow process in the protein and oxidative stability of white wines

In this work the impact of an innovative protein stabilization method (TiO2-based composite sorbent material coupled with a prototype device operating under continuous flow) has been tested in terms of protein and oxidative stability of white wines. Optimal process parameters (duration 60 min; flow rate 1.5 ± 0.1 L/h in 6 cycle rates/h) ensured an average 32.5 % reduction of total proteins; the nanoporous TiO2 film supported on inert glass beads acted as selective sorbent for pathogenesis-related proteins (PRPs, 10–60 kDa) responsible for wine instability, based on the protein stability studies (heat-test) performed in the experimental wines. The stabilization process has been tested for the release of contaminants (Ti), and the innovative treatment has been proven to preserve wine from oxidation also delaying the browning onset under extreme storage conditions.

The implementation of the environmental impact assessment in Fukushima contaminated water discharge: an analysis of the international legal framework

Japan is discharging nuclear contaminated water from the 2011 Fukushima incident into the sea after treatment with the Advanced Liquid Processing System (ALPS). This process is expected to continue for decades, as planned by the Japanese government. This decision sparks opposition from many countries and international organizations, as well as constant protests from people in Japan and neighboring countries. Although there are no international documents specifically addressing the discharge of contaminants from a nuclear accident, it is found that the LOS Convention, treaties on nuclear safety, and international environmental laws provide the basis and legal framework for requiring Japan to implement environmental impact assessments throughout the entire process of Fukushima contaminated water discharge. First, this paper evaluates the consistency between the measures taken before Japan’s decision to discharge contaminated water into the sea and the requirements under international laws. Second, this paper further examines the substantive and procedural requirements under international law for the entire process of Fukushima contaminated water discharge. It identifies substantive criteria to be applied in assessing the environmental impact of Fukushima contaminated water discharge based on international documents and explores the procedural requirements to assure transparency, prudence, and accountability of the assessment. Finally, given the potential transboundary damage caused by the discharge of nuclear-contaminated water into the sea, this paper proposes that a new multi-stakeholder cooperative mechanism is necessary to achieve effective and credible monitoring and respond to the claims of potentially affected parties. In addition to providing a legal framework for the environmental impact assessment in the Fukushima case, this paper may also contribute to the proper disposal of nuclear contaminants in future nuclear accidents.

Tackling Low-Value Plastics: Environmental and Health Concerns

Plastic pollution, spanning macroplastics to nanoplastics, poses multifaceted challenges. Low-value plastics (LVP), like multi-layered plastics (MLP) and soft plastics, are often discarded, exacerbating environmental issues. LVP's classification, with high collection costs and complex recycling, demands immediate attention. This study explores LVP management solutions, including converting to plastic lumber and RDF products. Anticipated advancements in multilayer plastic recycling offer hope, with downcycling as an option. LVP's environmental and health impacts, including microplastic contamination and toxin release during incineration, underscore the need for sustainable waste practices and plastic alternatives. Addressing LVP is crucial for environmental and human health, ensuring sustainability. Keywords: Low-value plastics, Multi-Layered Plastic (MLP), Health implications, Recycling challenges

Reviewing Perovskite Oxide-Based Materials for the Effective Treatment of Antibiotic-Polluted Environments: Challenges, Trends, and New Insights

Society confronts the pressing environmental challenges posed by the pervasive presence of toxic pollutants in aquatic ecosystems. The repercussions of contaminant release extend far and wide, endangering marine life and human well-being. While various techniques such as bioremediation, filtration, and adsorption have been employed for wastewater treatment, they grapple with cost effectiveness and overall efficiency issues. Advanced oxidative processes, including photocatalysis and Fenton, have emerged as viable solutions in response to the emerging contaminants. However, the efficacy of photocatalysis largely hinges on the choice of catalyst. Their distinctive attributes, such as chemical defects and exceptional stability, make perovskite oxides a promising catalyst. These materials can be synthesized through diverse methods, rendering them versatile and adaptable for widespread applications. Ongoing research endeavors are diligently focused on enhancing the performance of perovskite oxides, optimizing their integration into catalytic processes, and exploring innovative approaches for material immobilization. This comprehensive review seeks to elucidate the most pivotal advances in perovskite oxides and their composites within the wastewater treatment domain. Additionally, it sheds light on burgeoning research trends and multifaceted challenges confronting this field, which present insights into techniques for treating the antibiotic-contaminated environment, delving into innovative strategies, green technologies, challenges, and emerging trends.

Nanocomposite materials for decontamination of highly toxic acid dye from aqueous streams

ABSTRACT The rising issue of water pollution, driven by industry, urbanisation, and population increase, needs urgent action to address the release of contaminants. This study tackles the critical need for a low-cost, highly efficient adsorbent to extract toxic dyes from aqueous streams. The innovation lies in the synthesis of Cu/TiO2-CWSP composite, and composites with varying percentages of copper doping and comparing Cu/TiO2-CWSP composites with other nanocomposites, such as Li/TiO2-CWSP, Na₂SiO₃-CWSP, and various CaO-Fe-based composites. The works thoroughly optimised important parameters, including adsorbent dosage, pH, initial dye concentration, and exposure period, demonstrating their major influence on dye removal efficiency. Furthermore, the study assessed the effect of beginning pH on the adjustment of final pH, demonstrating variable efficiency levels depending on initial conditions. Recent research has evaluated numerous adsorbents, analysed by SEM. The highest % removal of acid green dye using Cu/TiO2-CWSP composite was at pH 7, dose of 0.5 g/L with a value of 99.12% achieved after 60 minutes only. The removal effectiveness of acid green dye improved as the percentage of Cu/TiO2 in the composite increased. Cu/TiO2-CWSP composite showed the presence of very fine particles at the surface of composite in SEM micrograph having a zeta Potential value of −20.9 mV. In conclusion, this study presents an innovative approach for efficiently removing acid green dye from aqueous solutions through adsorption-photocatalysis synergy. The findings contribute to addressing the critical issue of water pollution, especially in the textile industry, offering a sustainable path towards cleaner water resources.

Occurrence and fate of CECs (OMPs, ARGs and pathogens) during decentralised treatment of black water and grey water

Decentralised wastewater treatment is becoming a suitable strategy to reduce cost and environmental impact. In this research, the performance of two technologies treating black water (BW) and grey water (GW) fractions of urban sewage is carried out in a decentralised treatment of the wastewater produced in three office buildings. An Anaerobic Membrane Bioreactor (AnMBR) treating BW and a Hybrid preanoxic Membrane Bioreactor (H-MBR) containing small plastic carrier elements, treating GW were operated at pilot scale. Their potential on reducing the release of contaminants of emerging concern (CECs) such as Organic Micropollutants (OMPs), Antibiotic Resistance Genes (ARGs) and pathogens was studied. After 226 d of operation, a stable operation was achieved in both systems: the AnMBR removed 92.4 ± 2.5 % of influent COD, and H-MBR removed 89.7 ± 3.5 %. Regarding OMPs, the profile of compounds differed between BW and GW, being BW the matrix with more compounds detected at higher concentrations (up to μg L−1). For example, in the case of ibuprofen the concentrations in BW were 23.63 ± 3.97 μg L−1, 3 orders of magnitude higher than those detected in GW. The most abundant ARGs were sulfonamide resistant genes (sul1) and integron class 1 (intl1) in both BW and GW. Pathogenic bacteria counts were reduced between 1 and 3 log units in the AnMBR. Bacterial loads in GW were much lower than in BW, being no bacterial re-growth observed for the GW effluents after treatment in the H-MBR. None of the selected enteric viruses was detected in GW treatment line.

A study of theoretical mechanism on wastewater components of paper industry with process generated radicals in gaseous and aqueous phase

The paper and pulp industries release a diverse array of hazardous chemicals into the atmosphere, water bodies, and soil. Papermaking is characterized by intricate stages including debarking, pulping, bleaching and washing. Each of these stages possesses the capacity to generate a spectrum of toxic pollutants which may be present in both gaseous and liquid phases. This includes substances such as fatty acids, aromatic compounds, polycyclic aromatic hydrocarbons, acetaldehyde, chlorinated phenols, lignin, cellulose, hemicellulose and wood extractives. Consequently, these industrial discharges contribute to the contamination of wastewater with a complex mixture of harmful compounds. Some of these compounds persist even after the secondary treatment process. The effluent from these industries contains benzaldehyde which is one of the aromatic aldehydes with the highest reported retention time. The present study focuses on the reactions between benzaldehyde and atmospheric radicals (NO, NO2, HO2, O2, and OH radical) using computational methods. The study holds prime importance in understanding reactions involving these compounds and eventually assessing their impact on the environment. Density Functional Theory (DFT) is used to calculate Gibbs’s free energy which shows the spontaneity of reactions. The results show that the production of nitrobenzaldehyde is more feasible with ∼ -53.64 kcal/mol than the other products, and these nitro derivatives are proven to have a role in the formation and growth of the secondary organic aerosols. The aqueous solution environment promotes the production of these compounds, and they have a higher reaction energy of ∼ -3.34 kcal/mol than the gas phase. The products of these reactions adversely impact health and the atmosphere, making it a necessity to decrease the reactivity of these reactions or to take necessary actions to restrict the release of these toxic contaminants before they react with atmospheric radicals.