Effluent Water Research Articles

Evaluation of Fish Biosolids as a Fertilizer for Organic Tomato Transplant Production

Interest among consumers in the availability of organically produced fruits and vegetables is increasing. Seafood demand is increasingly being met by fish raised using aquaculture methods that provide fish excretory products that can meet organic standards for nutrient sources for organic vegetables. We conducted an experiment in a glass greenhouse to evaluate fish biosolids as a substrate amendment for organic tomato transplant production. We compared the fish biosolids treatment to several different organic fertilizers, along with a commonly used inorganic slow-release fertilizer (Osmocote). All treatments used a target N concentration of 400 mg/L incorporated into the substrate and we also included fish biosolids treatments of 200 and 800 mg N/L. Plant performance was monitored for 4 weeks starting with commercially available 2-week-old seedlings. The results showed that the 800 mg N/L fish biosolids treatment compared very favorably with the conventional Osmocote treatment at the conclusion of the trial. The 800 mg N/L fish biosolids treatment exceeded the Osmocote treatment for chlorophyll content and for leaf number for the first 3 weeks of the 4-week trial. Grower management protocols could further improve seedling performance by providing additional top dressings of fish biosolids or fish effluent waters as plants age.

From Isolation to Application: Utilising Phage-Antibiotic Synergy in Murine Bacteremia Model to Combat Multidrug-Resistant Enterococcus faecalis.

Enterococcus species, natural inhabitants of the human gut, have become major causes of life-threatening bloodstream infections (BSIs) and the third most frequent cause of hospital-acquired bacteremia. The rise of high-level gentamicin resistance (HLGR) in enterococcal isolates complicates treatment and revives bacteriophage therapy. This study isolated and identified forty E. faecalis clinical isolates, with 30% exhibiting HLGR. The HLGR5 isolate, resistant to fosfomycin, vancomycin, and linezolid, was used to isolate the vB_EfaS_SZ1 phage from effluent water. This phage specifically lysed 42% of HLGR isolates. vB_EfaS_SZ1 demonstrated beneficial traits, including thermal stability, acid-base tolerance, a short latent period, and a large burst size. The phage genome comprises a 40,942 bp linear double-stranded DNA with 65 open reading frames (ORFs). The genome closely resembled Enterococcus phages, classifying it within the Efquatrovirus genus. Phage-antibiotic synergy was assessed using checkerboard assays and time-killing analyses, revealing enhanced bacteriolytic activity of ampicillin and fosfomycin, with significant reductions in minimum inhibitory concentration values. In a mouse bacteremia model, phage-antibiotic combinations significantly reduced E. faecalis liver burden compared to monotherapies. Histopathological analysis confirmed therapeutic synergy, showing reduced inflammation and improved hepatocyte regeneration. These findings underscore the potential of phage vB_EfaS_SZ1 as an adjunct to antibiotic therapy for resistant enterococcal bacteremia.

Genomic epidemiology of extended-spectrum beta-lactamase-producing Escherichia coli from humans and a river in Aotearoa New Zealand.

In Aotearoa New Zealand, urinary tract infections in humans are commonly caused by extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli. This group of antimicrobial-resistant bacteria are often multidrug resistant. However, there is limited information on ESBL-producing E. coli found in the environment and their link with human clinical isolates. In this study, we examined the genetic relationship between environmental and human clinical ESBL-producing E. coli and isolates collected in parallel within the same area over 14 months. Environmental samples were collected from treated effluent, stormwater and multiple locations along an Aotearoa New Zealand river. Treated effluent, stormwater and river water sourced downstream of the treated effluent outlet were the main samples that were positive for ESBL-producing E. coli (7/14 samples, 50.0%; 3/6 samples, 50%; and 15/28 samples, 54%, respectively). Whole-genome sequence comparison was carried out on 307 human clinical and 45 environmental ESBL-producing E. coli isolates. Sequence type 131 was dominant for both clinical (147/307, 47.9%) and environmental isolates (11/45, 24.4%). Only one ESBL gene was detected in each isolate. Among the clinical isolates, the most prevalent ESBL genes were bla CTX-M-27 (134/307, 43.6%) and bla CTX-M-15 (134/307, 43.6%). Among the environmental isolates, bla CTX-M-15 (28/45, 62.2%) was the most prevalent gene. A core SNP analysis of these isolates suggested that some strains were shared between humans and the local river. These results highlight the importance of understanding different transmission pathways for the spread of ESBL-producing E. coli.

Research on Energy Savings through Floating DO Measuring Device in SBR Wastewater Treatment Method

Objectives : The objective of this study is to propose an optimal operational control method to ensure stable effluent water quality and reduce treatment costs in the SBR(Sequencing Batch Reactor) wastewater treatment process. In particular, the study aims to maintain the dissolved oxygen(DO) concentration required for microorganisms while reducing power costs associated with excessive aeration.Methods : To address issues with conventional fixed DO sensors, such as scum formation, inaccuracies caused by bubbles and strong flow velocities during aeration, and reduced reliability due to fluctuating water levels, a floating DO sensor was introduced to measure DO concentrations in real-time. Based on these real-time measurements, the optimal DO concentration required for microbial activity was calculated, and a system was designed to automatically control the airflow rate set value(SV) of the turbo blower.Results and Discussion : The application of a single-variable DO control method effectively reduced the power consumption required for aeration in the SBR aeration tank. This approach prevented energy waste caused by excessive aeration while maintaining the appropriate DO concentration needed for microbial activity. These results demonstrate that the proposed method improves the reliability and efficiency of the system.Conclusion : The real-time DO control method using a floating DO sensor enables energy savings and ensures stable effluent water quality in the SBR process. The proposed method overcomes the limitations of conventional fixed DO sensors, contributing to reduced power costs and improved process efficiency.

Examination of earthworm abundance; biomass andcorrelations of soil organic matter in an irrigated (with river and catfish effluent water) and mulched agroforestry system

Examination of earthworm abundance; biomass andcorrelations of soil organic matter in an irrigated (with river and catfish effluent water) and mulched agroforestry system

Research on Impact of Equity Costs and Environmental Costs on Supply-Side Classified Water Pricing

The classified water pricing system is an effective measure for promoting the rational utilization of water resources under market mechanisms. Studying the water prices of three different types of water sources, including reservoir water, river water, and wastewater treatment plant effluent, is the basis for promoting the use of reclaimed water. However, there remains a spectrum of viewpoints on how to establish a pricing mechanism for reclaimed water at present. This study primarily focuses on the multi-level quality-separated water supply system in Yiwu City, China. It analyzes the limitations of the current water pricing formation mechanism and the externality of integrating reclaimed water into the unified allocation of multiple water sources. Based on the principles of full-cost water pricing and externality theory, a supply-side classified water pricing permit cost and pricing calculation model, covering the entire process of the social water cycle, is proposed. It focuses on the analysis of the impact of equity costs and environmental costs on supply-side classified water pricing. The Shapley value method is used for the technology of cost allocation among stakeholders to reasonably distribute the calculated water pricing of reclaimed water. The price of reclaimed water varies depending on the user type, with residential users paying 2.93 CNY/t, industrial users 4.00 CNY/t, and government allocations at 8.52 CNY/t. Compared with the classified water prices of various stakeholders on the user side of reservoir water, reclaimed water has a significant price advantage. This research demonstrates that the supply-side classified water pricing model, which includes a permit cost and pricing calculation framework, can encourage the supply of higher-quality water at corresponding higher prices, while also providing the internalization of external costs. Furthermore, the Shapley value method of cost allocation can realize the fair burden of stakeholders on the calculated water price and maintain the competitive advantage of reclaimed water prices.

Graphene oxide functionalized with L-asparagine applied to crystal violet dye removal from water and wastewater.

The efficiency of graphene oxide functionalized with L-asparagine (GO@L-Asn) as adsorbent for crystal violet (CV) dye removal from water and wastewater was investigated. The surface and textural properties of this new nanomaterial were characterized by pH at point of zero charge, Fourier-transform infrared spectroscopy, scanning electron microscopy, X-ray diffraction, and Brunauer-Emmet-Teller technique. The main experimental variables involved in dye adsorption process were evaluated and optimized. Adsorption equilibrium was reached after 120min, using 25mL of 50mg L-1 CV, and 30mg of GO@L-Asn at pH 8 and 328K. The Freundlich isotherm model was the most appropriate to correlate the experimental data, showing a maximum adsorption capacity of 102.5mgg-1 (R2 = 0.992). The results of the kinetic study were fitted with the pseudo-first order model (R2 = 0.997). Thermodynamic calculations indicated that the CV removal was an endothermic, spontaneous, and favorable process. Characterization and modeling results showed that an adsorption mechanism involving physisorption was associated with CV removal. This novel adsorbent was applied to remove CV from samples of natural water and textile effluents, obtaining pollutant removal percentages up to 92.0%, which indicated the high efficiency of GO@L-Asn for the treatment of complex matrices.

A novel metal-free perylene-functionalized graphite adsorbent for efficient antibiotic removal from wastewater.

Adsorption remains a widely utilized and effective technique for removing chemical contaminants from polluted water, and novel adsorbents are currently in the process of being developed. The presence of antibiotics residues in aqueous effluents is a potential concern due to their potential adverse effects on living organisms. In this work, perylene tetracarboxylic acid-functionalized expanded graphite (PTCA-EG) was synthesized as a metal-free adsorbent and its potential for efficient treatment of contaminated wastewater with cefalexin (CLX) antibiotic was studied. The experimental variables were modeled and optimized using central composite design (CCD) and response surface methodology (RSM) to maximize adsorption efficiency. In this regard, the contact time of 20min, solution pH of 7.0, adsorbent dosage of 18mg, and initial CLX concentration of 45mg L-1 were found to be the optimum conditions for adsorptive removal of CLX with a maximum efficiency of 99 ± 1.21%. In addition, the adsorption equilibrium data were well analyzed with isotherm, kinetic, and thermodynamic studies. The isotherm results revealed the adsorption process was favorable and took place on the heterogeneous surface. Moreover, the Langmuir maximum adsorption capacity (Qmax) was determined as 220.7mgg-1. Also, thermodynamic parameters revealed the spontaneity and endothermic nature of the adsorption process. The reusability studies demonstrated that the spent PTCA-EG can be easily regenerated through NaOH solution (0.01mol L-1) and reused for six cycles without any significant decrease in its adsorption efficiency. Also, the PTCA-EG showed excellent behavior in adsorptive removal of CLX in real water samples including river water (96.61 ± 1.82%) and hospital effluents (91.91 ± 3.41-93.69 ± 3.06%).

IoT-Based Tryptophan-like Fluorescence Portable Device to Monitor the Indicators for Microbial Quality by E. coli and Biochemical Oxygen Demand (BOD5)

Tryptophan-like fluorescence (TLF) is a key indicator of water contamination, particularly of microbial origin and biodegradable organic compounds. This study introduces an Internet of Things (IoT)-enabled portable device (IoT-TLF-PD) for real-time monitoring of microbial quality and biochemical oxygen demand (BOD5). The device was tested using surface water (S1), secondary wastewater (S2), and final wastewater effluents (S3). Results showed significant correlations between TLF intensity, Escherichia coli (E. coli) counts, and BOD5, with R2 values of 0.77 (S1), 0.61 (S2), and 0.76 (S3) for BOD5, and 0.60 (S2) to 0.68 (S3) for E. coli. Considering various water samples, a strong correlation was found between E. coli and BOD5 with TLF intensity normalized by total organic carbon (TOC) concentration (TLF intensity/TOC). The R2 value for E. coli was 0.92, and for BOD5, it was 0.77. This indicates the necessity of accounting for organic matter concentration when interpreting TLF intensity in water quality assessments. The study confirmed the potential of the IoT-TLF-PD to serve as a cost-effective, real-time indicator for assessing water quality, especially for detecting microbial contamination. This technology offers a valuable tool for environmental monitoring and water management.

Long term performance of Nature-Based Solutions as decentralized wastewater treatment: a case study of a retail store in southern Italy

The aim of this study is to evaluate the removal efficiency and the hydraulic behavior of the 10-year-old hybrid treatment wetland (TW) system treating effluents of the IKEA® store of Catania (Eastern Sicily, Italy), under Mediterranean semi-arid climate conditions. The system is placed downstream to the conventional wastewater (WW) treatment of the store, that includes a sequential batch reactor (SBR) followed by a horizontal subsurface treatment wetland (HF) unit and two vertical subsurface flow treatment wetlands (VF1 and VF2) units. The assessment of chemical, physical, and microbiological parameters in treated WW was carried out through regular monitoring activities, occurring approximately on a monthly basis, over a 8-year period spanning from 2016 to 2023. Up to 72 samples were collected for the following parameters measurements: total suspended solids (TSS), BOD5, COD, total phosphorus (TP), ammonia (as NH4), nitrate (as NO3-N), nitrite (as NO2-N), total nitrogen (TN) and E. coli. Hydraulic conductivity at saturation (Ks) measurements and tracer tests were conducted to evaluate the extent of clogging and to characterize the hydraulic behavior within the HF unit. Results obtained during the entire monitoring period show the following mean and standard errors (±) removal efficiency ranges (%): TN 21(±11)-80(±9); TSS 18(±42)-95(±3); COD 28(±23)-93(±2); BOD5 31(±10)-85(±44); TP 14(±6)-49(±19); NH4 50(±50)-95(±3); E. coli was abated with a mean range of 3.3(±0.2)-4.8(±0.4) Ulog reduction, reaching not detectable values in most samples analyzed since 2018. The efficacy of the treatment system is assessed in the context of both national and European regulatory frameworks governing effluent discharge and water reuse standards. Ks values and tracer test results agree in showing the progressive clogging of the HF unit influencing the hydraulic behavior of the unit giving useful on the management of TWs in Mediterranean area. Finally, the performance results also indicate that the overall treatment is not affected by the HF unit clogging.

Exploring plant virus diversity in wastewater and reclaimed water through metagenomic analysis

The use of reclaimed water for agricultural activities is being widely employed to address drought and water scarcity. Nevertheless, the disinfection processes do not consistently facilitate the complete removal of all eukaryotic viruses within these reclaimed waters. Consequently, it may pose a risk not only to humans but also to irrigated plants. We analyzed 48 influent and 48 effluent samples from 4 different wastewater treatment plants (WWTPs) by high-throughput sequencing (HTS) to characterize plant-associated virome over a one-year period. Our results showed high levels of plant viruses in both influent and effluent waters. The predominant family identified was Virgaviridae, recognized for its high environmental persistence. Notably, the identification of Tomato Brown Rugose Fruit virus (ToBRFV), classified as a harmful organism by the European Union and subject to strict containment measures to control its spread, highlights the importance of monitoring reclaimed water to mitigate the spread of such viruses into the environment. These findings underscore the need of analyzing reclaimed water from a One Health perspective, ensuring its safety for humans, animals, plants, and the environment alike.

Hydrocarbon Fuel Cell Membranes: Do We Need New Chemical Durability Testing Protocols?

Hydrocarbon proton exchange membranes (PEMs) for fuel cells have recently received increased attention due to growing environmental concerns about the use of per- and polyfluoroalkyl substances. The chemical accelerated stress test (AST) protocol for membranes developed by the US Department of Energy (DOE), which is based on the understanding of the degradation mechanism of perfluoroalkylsulfonic acid PEMs, has been widely adopted to assess newly developed hydrocarbon PEMs. However, due to different polymer chemistry and membrane degradation mechanisms, the DOE chemical AST protocol may not be suitable for hydrocarbon PEMs.In this study, the influence of two key operating parameters, i.e. relative humidity (RH) and O2 partial pressure (p O2), on the chemical degradation of hydrocarbon PEMs was investigated in order to design a more suitable chemical AST protocol for hydrocarbon PEMs. Sulfonated poly(ether ether ketone) (SPEEK) was selected as a representative material for non-fluorinated hydrocarbon PEMs. Solution-cast membranes of ~22 μm thickness were wet-assembled in a single fuel cell (16 cm2 active area) for fixed time (4 days) open circuit voltage (OCV) holding tests at different RHs and p O2. Under 100% RH, H2/O2, the membrane failed the fastest within 40 hours (Figure 1a). This could be related to higher gas crossover (Figure 1b), which leads to more oxidative radicals, such as HO•, being generated. Fuel cell effluent water was periodically collected from both the anode and cathode sides for analysis by UV-vis spectroscopy and ion chromatography (IC). Hydroquinone-like degradation products were detected by UV-vis spectroscopy. Furthermore, under 100% RH, H2/O2, the degradation products showed the strongest signal in the anodic effluent water. IC results of sulfate ion release suggested that the higher the RH (also p O2), the more severe the membrane degradation. Post-test ion exchange capacity (IEC) measurements showed that the average IEC loss rate is the highest under 100% RH, H2/O2 (~0.15 %/h), while the lowest under 30% RH, H2/air (~0.01 %/h), again indicating that 100% RH, H2/O2 could be a promising protocol for AST of hydrocarbon PEMs. Figure 1

Understanding Durability of Polymer Electrolyte Membrane Water Electrolyzers

Hydrogen is positioned to play a pivotal role in the future energy landscape, bolstered by the increasing adoption of renewable energy sources. The U.S. Department of Energy (DOE) has initiated the Hydrogen earth shot, with a goal of achieving a cost target of $1 per kilogram of hydrogen within a decade. Polymer electrolyte membrane water electrolyzers (PEMWE) are at the forefront of enabling hydrogen production from renewable electricity. Yet, achieving the 80000 h operational lifetime remains a critical challenge for the commercial viability of PEMWE.1 An in-depth understanding of the conditions affecting the degradation of critical PEMWE components including the catalyst layer, membrane, and porous transport layers is crucial for achieving the durability target of PEMWE.In this study, we explore the effect of various operating conditions, such as temperature, pressure, and cycling vs. hold of voltage or current, and the membrane electrode assembly composition, including catalyst loading, membrane thickness, and incorporation of gas recombination catalyst (GRC), on degradation in PEMWE. To assess the degradation rate, our protocol involved long duration durability tests, alternating between high and low current density cycles with long holding periods and rapid cycling. Electrochemical characterization including polarization curve, electrochemical impedance spectroscopy, and cyclic voltammetry will be presented. Additionally, electron microscopy and X-ray spectroscopy analysis provides insight into changes in the catalyst layer. The second part of the study focuses on understating membrane degradation in PEMWEs. Through periodic analysis of the cathode and anode effluent water during long duration current density holds, the fluorine emission rate (FER) was estimated, a key metric for assessing membrane and ionomer loss. Preliminary investigation reveals that incorporation of GRC in the membrane reduces hydrogen crossover, thereby lowering the FER and the degradation rate. This study enhances our understanding of PEMWE degradation, offering critical data to develop accelerated stress test (AST) protocols.Acknowledgment:This research is supported by the U.S. Department of Energy (DOE) Hydrogen and Fuel Cell Technologies Office through the Hydrogen from Next-generation Electrolyzers of Water (H2NEW) consortium.Reference: Tomic, A. Z., Pivac, I., Barbir, F., Journal of Power Sources (2023) 557

Durability Study of Membrane Electrode Assembly for Heavy-Duty Fuel Cells

Polymer electrolyte membrane fuel cells (PEMFCs) are a zero emission replacement for heavy duty applications due to their range, energy density and fast refueling times.[1] In 2020, the U.S. Department of Energy (DOE) lunched the Million Mile Fuel Cell Truck (M2FCT) consortium to fund fuel cell R&D to meet heavy duty truck standards.[2] Durability studies focusing on heavy-duty applications for advanced materials testing under the M2FCT consortium have been extensively explored and continue to be analyzed to standardize the evaluation of next generation fuel cell materials.This study combines in situ electrochemical characterization with ex situ analysis of single cell PEMFCs membrane electrode assemblies (MEAs) to predict long-term durability for heavy-duty applications. Various accelerated stress test (AST) parameters were analyzed to determine the stressors affecting the long-term durability. Local degradation resulting from repeated high voltage to low current cycles was analyzed by testing state-of-the-art materials. High potential holds at various conditions were analyzed to determine membrane chemical degradation. Repeated wet and dry cycles were performed to test the membrane mechanical durability. In situ electrochemical analysis include mass activity, electrochemical surface area, hydrogen crossover, and polarization curves were collected and compared among the MEAs. Ex situ analysis includes quantification of membrane thinning at end of life and fluoride emission rate measurement for water effluent throughout the test was conducted to study the membrane degradation. Acknowledgement: This work was supported by the Hydrogen and Fuel Cell Technologies Office (HFTO), Office of Energy Efficiency and Renewable Energy (EERE), US DOE through the Million Mile Fuel Cell Truck (M2FCT) consortium, technology managers G. Kleen and D. Papageorgopoulos.

The efficacy of wastewater treatment plant on removal of perfluoroalkyl substances and their impacts on the coastal environment of False Bay, South Africa

Per- and polyfluoroalkyl substances (PFASs), which have their origins in both industrial processes and consumer products, can be detected at all treatment stages in wastewater treatment plants (WWTPs). Quantifying the emissions of PFAS from WWTPs into the marine environment is crucial because of their potential impacts on receiving aquatic ecosystems. In this study, the levels of five PFAS were measured in both influent and effluent sewage water samples obtained from a municipal WWTP, the discharges of which flow into False Bay, on the Indian Ocean coast of Cape Town, South Africa. Additionally, seawater, sediment, and biota samples from eight sites along the False Bay coast were also analysed. Results showed high prevalence of PFAS in the different environmental matrices. Perfluorononanoic acid was most dominant in all these matrices with maximum concentration in wastewater, 10.50 ng/L; seawater, 18.76 ng/L; marine sediment, 239.65 ng/g dry weight (dw); invertebrates, 0.72–2.45 µg/g dw; seaweed, 0.36–2.01 µg/g dw. The study used the chemical fingerprint of five PFASs detected in WWTP effluents to track their dispersion across a large, previously pristine marine environment and examined how each chemical accumulated in different marine organisms. The study also demonstrates that primary and secondary wastewater treatment processes cannot fully remove such compounds. There is thus a need to improve effluent quality before its release into the environment and promote continuous monitoring focusing on the sources of PFAS, including their potential transformation products, their environmental fate and ecological risks, particularly in areas receiving effluents from WWTP.

Water treatment of recirculating aquaculture system (RAS) effluent water through microalgal biofilms

This research studied the growth of microalgae (Chlorella vulgaris and Phaeodactylum tricornutum) on a biofilm reactor using effluent water from salmon production in a recirculating aquaculture system (RAS). RAS effluent water contains considerable amounts of nitrate and small amounts of phosphate, that stem from dissolved excess feed and fish faeces. In microalgae growth experiments, we tested a twin-layer biofilm reactor, which has one layer for substrate distribution (RAS effluent water-based medium) and adhered onto that, a carrier layer for biofilm cultivation. First, we tested five different carrier materials (newsprint, filter paper, polypropylene, viscose/polyester mix, viscose) to assess the microalgae's attachment ability of the material, where the viscose fibre material proved to be the most suitable. The biofilm reactor design had to be improved for saltwater suitability, as water evaporation caused changes in salinity and nutrient concentrations and ultimately led to the formation of salt crusts on the biofilm and clogging of the irrigation system. A dilution of the medium with osmosis water compensated the evaporation rate and a technical improvement of the irrigation system established stable cultivation conditions. The biofilm reactor was then tested for all three water types (Chlorella for freshwater, Phaeodactylum for brackish water and saltwater) that are discharged during a RAS production cycle for salmon. Microalgae paste was used for inoculation of the biofilm carrier material and after a short maturation phase the biofilm reactor was harvested every three days. This study demonstrated that a complete uptake of nitrate and phosphate from RAS effluent water through microalgae cultivation is possible, and the biofilm reactor is able to handle changes in nutrient concentrations and salinity. Biomass productivity for Phaeodactylum cultivated on brackish RAS medium was highest (15.28 g m−2 d−1), compared to saltwater RAS medium (4.35 g m−2 d−1) and Chlorella on freshwater RAS medium (4.25 g m−2 d−1).

Determination of Polycyclic Aromatic Hydrocarbons in Water Samples Using Solid‐Phase Extraction Procedure and High‐Performance Liquid Chromatography With Fluorescence Detection

ABSTRACTSolid phase extraction (SPE) procedure followed by high‐performance liquid chromatography with fluorescence detection was evaluated for determination of 14 priority polycyclic aromatic hydrocarbons (PAHs) pollutants in water samples. Diverse parameters affecting extraction efficiency such as the nature and volume of eluent solvent, volume and pH of the water sample, and quantity and nature of sorbent phase were studied and optimized. SPE was carried out on Bond Elut C18 cartridge and high recoveries were obtained using 1000 mg of the sorbent for the treatment of a 500 mL water sample. PAH recoveries ranged from 60.3% to 93.3% for 500 mL treated water samples. The developed method gives very low detection limits ranging between 0.03 and 12 ng/mL and it has been applied successfully to different environmental water samples such as tap water, mineral water, surface water, treated wastewater, and industrial effluents. Results showed the presence of PAHs especially in industrial effluent from the Bizerte region with ∑PAHs means value of 33.76 mg/L and in treated wastewater samples collected from North Tunisia with ∑PAHs concentrations levels of 0.81, 1.17, 0.97, and 0.72 mg/L in Bizerte, Tunis, Ben Arous, and Beja wastewater treatment plants, respectively.

A novel approach for multivariate time series interval prediction of water quality at wastewater treatment plants.

This study proposes a novel approach for predicting variations in water quality at wastewater treatment plants (WWTPs), which is crucial for optimizing process management and pollution control. The model combines convolutional bi-directional gated recursive units (CBGRUs) with adaptive bandwidth kernel function density estimation (ABKDE) to address the challenge of multivariate time series interval prediction of WWTP water quality. Initially, wavelet transform (WT) was employed to smooth the water quality data, reducing noise and fluctuations. Linear correlation coefficient (CC) and non-linear mutual information (MI) techniques were then utilized to select input variables. The CBGRU model was applied to capture temporal correlations in the time series, integrating the Multiple Heads of Attention (MHA) mechanism to enhance the model's ability to comprehend complex relationships within the data. ABKDE was employed, supplemented by bootstrap to establish upper and lower bounds of the prediction intervals. Ablation experiments and comparative analyses with benchmark models confirmed the superior performance of the model in point prediction, interval prediction, the analysis of forecast period, and fluctuation detection for water quality data. Also, this study verifies the model's broad applicability and robustness to anomalous data. This study contributes significantly to improved effluent treatment efficiency and water quality control in WWTPs.

Measuring Microplastic Concentrations in Water by Electrical Impedance Spectroscopy

Plastics are vital for society, but their usage has grown exponentially and contributes to the growth of pollution worldwide. The World Health Organization, WHO, already reported that microplastics (MPs) are found everywhere, in waste and fresh water, and in the air and soil. Regarding water effluents, waste-water treatment plants only minimize the problem, trapping only larger size particles. In contrast, smaller ones remain in oxidation ponds or sewage sludges, or are even released to aquifers environment. Classic procedures for MPs detection are still quite laborious, and are usually conducted off-line, involving several steps and expensive equipment. Electrical Impedance Spectroscopy, EIS, is a technique that allows the analysis of a system’s electrical response, yielding helpful information about its domain-dependent on physical-chemical properties. Due to the superficial electronegativity of MPs’ particles, EIS may allow to attain the purpose of the present work: to provide a fast and reliable method to detect/estimate MPs’ concentration in water effluents. Among the most common microplastics are Polyethylene, PE, and Polyvinyl Chloride, PVC. Using the developed setup and experimental data collection methodology, the authors could differentiate between MPs’ suspensions containing the same concentration of the different evaluated MPs, PVC and PE, and assess PVC concentration variation, in the interval between 0.03 to 0.5 g (w/w), with an error, estimated based on the obtained impedance modulus, around or below 3% for the entire stimulus signal frequency range (from 100 Hz to 40 MHz) for the PVC particles.

Microplastic Contamination in Landfill Leachate and Surface Water: Assessment of Wastewater Treatment Efficiency at the Nonthaburi Waste Management Center, Thailand

Microplastics (MPs), plastic particles smaller than 5 mm, have emerged as a significant environmental concern, particularly as contaminants originating from landfills. Landfills can serve as a major source of MPs, potentially releasing them into surface water through leachate. This study aims to investigate the contamination of MPs in leachate and surface water, as well as to evaluate the efficiency of landfill wastewater treatment in removing these particles. The research was conducted at the Waste Management Center of the Nonthaburi Provincial Administrative Organization, Thailand, with samples collected in June 2023. Sampling included two leachate sources, influent and effluent from the treatment system and surface water. The abundance and characteristics of MPs in each sample were analyzed. Results indicated a significant presence of MPs in leachate, with an average concentration of 173.98 pieces/L, while concentrations in influent, effluent and surface water were 38.40 pieces/L, 10.80 pieces/L and 11.33 pieces/L, respectively. MPs in all samples were predominantly in the size range of 16-100 µm, corresponding to 71.28-93.75% of the total particles. Polypropylene was the dominant polymer in leachate (69.66%) and effluent (48.94%), whereas acrylate copolymer (96.53%) and polytetrafluoroethylene (44.12%) were the major types found in influent and surface water, respectively. The wastewater treatment system of the landfill demonstrated an overall removal efficiency of 71.88% for MPs in leachate. These findings highlight the extent of MP contamination in landfill environments and the importance of improving treatment processes to mitigate their release into surrounding ecosystems.