Effluent Concentrations Research Articles

Microplastics in two different constructed wetlands systems for wastewater treatment: Removal and fate

Wastewater is one of the main sources of microplastics (MPs) in the environment, but so far, most research has focused on large-scale centralized wastewater treatment plants (WWTPs). This study investigated the removal and fate of MPs in two small-scale WWTPs (S1 and S2) using different constructed wetlands (CWs). Samples from the wastewater, substrates and macroinvertebrates of CWs were collected and analyzed to investigate the fate of MPs. Results showed that the total removal efficiency for MPs was 97 % in both S1 and S2 WWTPs, resulting in effluent concentrations approximately 0.5 particles/L. The CW units of S1 and S2 contributed 92 % and 89 %, respectively, indicating that both VF CWs and HSSF CWs have efficient MPs removal capability. Moreover, fibers were the most abundant shape detected in wastewater (74 % in S1 and 83 % in S2), as well as in substrates and macroinvertebrates. In the S2 CW, fibers had a lower removal efficiency (89 %) compared with other shapes, while in S1 CWs, all shapes had 93 % removal efficiency. The concentration of MPs in surface substrates (0.57–0.71 particles/g dry weight) of CWs did not show any differences between different CWs (p > 0.05). The concentration of MPs inside macroinvertebrates showed a significant decline between S1 CW1 (154.9 particles/g dw on average) and S1 CW2 (94.4 particles/g dw) (p < 0.05), which were consistent with the concentration of MPs in the influent of each CW. This study provides insights into MPs removal by different kinds of CWs and is beneficial for management of MPs with CWs.

Evaluation of physical, chemical, and microbiological characteristics of waste stabilization ponds, Giza, Egypt

Wastewater treatment plants (WWTPs) contain a diverse array of microbes, underscoring the need for regular monitoring to ensure treatment efficacy and protect health. However, detailed studies on waste stabilization ponds (WSPs) are scarce. This study evaluates a full-scale WSP, located in Giza Governorate, Egypt, including anaerobic, facultative, and maturation ponds, examining an array of parameters such as enteric viruses, microeukaryotes (protozoa and algae), bacterial indicators, bacterial pathogens, and physicochemical characteristics. Utilizing multivariate statistical models, we identified significant distinctions in physicochemical parameters and microbial communities, primarily driven by treatment stages rather than temporal variations. In addition, seven viruses (human rotavirus, adenovirus, norovirus, astrovirus, hepatitis A virus, polyomavirus, and papillomavirus) were detected during the different stages (inlet, anaerobic, facultative, and outlet) of the WSP, except norovirus and papillomavirus were absent in the outlet stage. The viral log means reductions ranged from 1.24 to 5.94, depending on the stage and virus type. The removal efficiency of bacterial pathogens was more than 99%. High throughput 18S rRNA gene amplicon sequencing indicated the dominance of animal parasitic Apicomplexa species and Vermamoeba spp. in the WSP. Network analysis indicated significant roles for Ciliophora in virus reduction. Notably, the maturation pond's outlet was dominated by Spirulina maxima, whose mat-forming tendencies may inhibit pathogen removal by providing protective shelters. Although the WSP effectively reduced pathogen levels, the high initial loads resulted in considerable concentrations in the final effluent, posing ongoing public health concerns. This study highlights the imperative of including pathogen standards in national regulations for wastewater reuse.

Autotaxin concentrations in peritoneal dialysis effluent reflect peritoneal function.

Peritoneal equilibration test (PET) has been used to monitor peritoneal function. A more convenient marker would be useful in clinical situations including home medical care. Autotaxin is known to leak into the interstitium as vascular permeability increases during the progression of tissue fibrosis. Therefore, we hypothesized that autotaxin concentrations in peritoneal dialysis (PD) effluent might reflect peritoneal function. This study enrolled 45 patients undergoing PD from 2016 to 2021. Autotaxin concentrations measured in PD effluent were evaluated for their associations with markers obtained from PET. Mean age was 69 years, and 33 patients were men. Univariate and multivariate analyses revealed that autotaxin concentrations are associated with dialysate/plasma creatinine ratio, end/start dialysate glucose ratio, and the dip in the dialysate sodium concentration, a marker of ultrafiltration capacity, at baseline (all p < 0.05). Autotaxin concentrations in PD effluent might be an adjunct marker that reflects peritoneal function.

Optimized ammonium-nitrate ratios in constructed wetlands for simultaneously efficient nitrogen removal and greenhouse gas reduction

Constructed wetlands (CWs) are increasingly employed for treating secondary tailwater treatment from wastewater treatment plants (WWTPs), addressing the challenges of nitrogen removal and greenhouse gas (GHG) emission reduction. This study explores the potential for enhancing nitrogen removal while reducing GHG emissions in vertical flow CWs by optimizing the influent ammonium-nitrate ratio in real tailwater scenarios. Six different influent ammonium-nitrate ratios (0:15, 1:20, 1:10, 1:5, 1:2, 1:1) were investigated and the results indicate that an ammonium-nitrate ratio of 1:5 achieves the highest total nitrogen (TN) removal efficiency of 77.50 ± 2.40 %, with the effluent concentrations below 4 mg/L. Conversely, a ratio of 1:10 minimized N2O emissions (0.027 mg/(m2⋅h)), representing just 0.054 ‰ of influent TN. Additionally, it was observed that increasing the ammonium-nitrate ratio influences microbial selectivity within the system. Moreover, a life cycle assessment further indicates that a 1:5 ratio poses the lowest potential environmental impact. These insights guide the design optimization of CWs for enhanced nitrogen removal and GHG mitigation, providing valuable strategies for tailwater management from WWTPs.

Treatment of Domestic Wastewater Using Membrane Bioreactor (MBR) Pilot Plant: A Case Study of Wastewater from Kklung Hok’s Treatment Pond and The Environmental Research and Training Centre (ERTC), Pathumthani, Thailand

This research performant of Membrane Bioreactor (MBR) pilot plant for treatment of Wastewater from Khlung Hok’s treatment pond volume of 250 liter and The Environmental Research and Training Centre (ERTC) volume of 100 liter, both wastewater was mix on MBR. Aeration was fed at air flow rate 150 l/min over two hours to provide the oxygen for microorganisms. Further, Aeration was fed continuously for 6 hours. sample were collected every one hour. Result found that: the wastewater variation of pH, DO, BOD, COD, NH4+, NO2– concentration of the feed tank from Khlung Hok’s treatment pond were 7.16, 0.60 mg/l, 95mg/l, 157 mg/l, 34.96 ppm and NO2 not found and from ERTC’s wastewater were 6.87, 0.41 mg/l, 93 mg/l, 160 mg/l, 21.23 ppm and 0.043 ppm, respectively. After air flow in MBR over 2 hour the concentration of influent was found 6.64, 0.60 mg/l, 48 mg/l, 105.67 mg/l, 22.30 ppm and 0.031 ppm, respectively. And during the whole process effluent pH concentration were between 6.64-7.46, DO were between 1.11-5.8 mg/l. The removal BOD efficiency were over 89.58% (on 5th hour), COD were over 75.39% (on 4th hour), NH4 were over 53.61% of (on first hour) and were over NO2 48.71% of (on 2nd hour), respectively. Result indicated that effective removal BOD, COD, NH4+ and NO2– by MBR could be achieved and increased in scale for use in the fieldwork or the treatment of wastewater in the environment.

Robust nitrogen removal via nitrification-partial denitrification / anammox to co-treat acrylic fiber wastewater and sewage without external carbon

Acrylic fiber (AF) wastewater is characterized by high levels of ammonia nitrogen, refractory organic compounds, and toxic substances, making biological nutrient removal challenging. Conventional biological treatment technologies are often ineffective due to the complex composition, high toxicity, and low C/N ratios of AF wastewater. In this study, a two-stage nitrification-partial denitrification/anammox (N-PDA) process was firstly developed for the combined treatment of AF wastewater and domestic sewage, which integrated nitrification-SBR(N-SBR) and partial denitrification/anammox-UASB (PDA-UASB). The N-SBR achieved stable nitrification (ARE=100 %, HRT=4.2 h) with increasing ratios of AF wastewater, while the PDA-UASB utilized organic carbon from domestic sewage to simultaneously remove nitrate (91.7 mg/L) and ammonium (66.3 mg/L) through the PDA pathway (HRT=11.3 h). After 200 days, the relative abundance of Candidatus Brocadia increased from 0.6 to 5.4 %, ensuring robust nitrogen removal performance. The system achieved effluent ammonium and total nitrogen concentrations below 1.0 mg/L and 15.0 mg/L, respectively, with a total nitrogen removal rate of 87 %. This study demonstrates the N-PDA process as an efficient, energy-saving, and cost-effective solution for treating AF wastewater without the additional organic carbon sources, enhancing nitrogen removal efficiency and operational stability.

Advanced N removal from low C/N sewage via a plug-flow anaerobic/oxic/anoxic (AOA) process: Intensification through partial nitrification, endogenous denitrification, partial denitrification, and anammox (PNEnD/A)

Achieving low-cost advanced nitrogen (N) removal from municipal wastewater treatment plants (WWTPs) remains a challenge. A plug-flow anaerobic/oxic/anoxic (AOA) system with a mixtures bypass (MBP) integrating partial nitrification (PN), endogenous carbon denitrification (EnD), partial denitrification (PD), and anaerobic ammonium oxidation (Anammox), was constructed to treat actual sewage with a low C/N ratio. The effluent concentrations and removal efficiency of total inorganic nitrogen (TIN) during stable operation were 2.9 ± 0.9 mg/L and 93.1 ± 2.0 %, respectively. EnD was enhanced by the MBP through the efficient utilization of polyhydroxyalkanoates generated in the anaerobic zone. PD was promoted by the addition of carries and sodium acetate to the anoxic tank and the subsequent implantation of the Anammox biofilm successfully coupled PD/A. Stable PN was obtained with a satisfactory nitrite accumulation ratio of 92.6 %, facilitated by carriers and the introduction of hydroxylamine in the oxic zone. Mass balance analysis revealed that EnD and Anammox contributed 40.8 % and 48.2 % of TIN removal, respectively. The enrichment and synergistic effects of ammonia-oxidizing bacteria, denitrifying bacteria, glycogen-accumulating organisms, and anaerobic ammonia-oxidizing bacteria formed a diverses bacterial basis for the establishment of PN, EnD, PD, and Anammox (PNEnD/A) in the AOA system. The successful integration of PNEnD/A into the AOA process provides an innovative approach for low-cost advanced N removal in WWTPs.

PSV-26 Effect of addition of Ascophyllum nodosum and Asparagopsis taxiformis, alone or in combination, to an herbage-based diet on in vitro fermentation in continuous culture

Abstract This study investigated the effect of individual or simultaneous addition of two macroalgae species on in vitro fermentation in continuous culture. Four single-flow continuous culture fermentors were fed an orchardgrass herbage-based (orchardgrass; Dactylis glomerata L.) basal diet and randomly assigned one of four treatments: 1) control (CON), no macroalgae addition; 2) Ascophyllum nodosum dosed at 2.5% dry matter (DM; ASC); 3) Asparagopsis taxiformis dosed at 0.5% DM (ATX); and 4) A. nodosum (2.5% DM) + A. taxiformis (0.5% DM) dosed simultaneously (AS+AT). Four experimental periods were conducted in a randomized block design with 7 d of treatment adaptation and 3 d of sample collection. Fermentors were fed 82 g of DM per day in 4 equal feedings. In the last 3 d of each experimental period, daily samples of total effluent were taken for analyses of ammonia N and volatile fatty acids (VFA). Effluent was composited by fermentor and analyzed for DM, ash, neutral and acid detergent fiber, and crude protein. Purine concentrations of effluent and bacterial isolates were determined to estimate partitioning of N flow into feed, bacterial, and ammonia N fractions. Methane (CH4) emissions were measured in each fermentor every 15 min using a Fourier transform infrared gas analyzer, and pH was recorded every 2 min. Data were analyzed using the MIXED procedure of SAS v 9.4 with pre-planned contrasts comparing each individual macroalgae to CON (CON vs. ASC and CON vs. ATX) and comparing A. taxiformis with and without simultaneous addition of A. nodosum (ATX vs. AS+AT). Significance was declared at P ≤ 0.05 and tendencies at 0.05 &amp;lt; P ≤ 0.10. Nutrient digestibilities, CH4 emissions, pH, and N metabolism variables were not affected (P &amp;gt; 0.10) in ASC compared with CON, but total VFA concentration increased (P &amp;lt; 0.05) by 10%. Contrarily, the ATX diet tended (P = 0.61) to have reduced true organic matter digestibility, reduced (P &amp;lt; 0.05) total VFA concentration by 11%, and reduced (P &amp;lt; 0.05) CH4 production by 99.9% versus CON. Simultaneous the combination of microalgae (AS+AT) did not further reduce (P &amp;gt; 0.10) nutrient digestibility or total VFA concentration compared with ATX, and did not change (P &amp;gt; 0.10) the degree of CH4 inhibition. However, A. nodosum did not mitigate (P &amp;gt; 0.10) any of the negative effects on fermentation associated with A. taxiformis, as nutrient digestibilities and N metabolism variables in AS+AT were also not different (P &amp;gt; 0.10) from ATX. While the macroalgae species, A. nodosum and A. taxiformis, led to different fermentation patterns when added individually to continuous culture fermentors, no negative or positive interactions were observed from their simultaneous addition.

Evaluation of a pilot-scale anaerobic biofilm reactor for the treatment of slaughterhouse effluents in rural areas

ABSTRACT Rural slaughterhouses often lack strict effluent treatment rules, resulting in inadequate treatment prior to release into water bodies. Slaughterhouse wastewater (SWW) is a high-strength effluent, posing risks of contamination to ecosystems and human health. To tackle the need for suitable technologies in these areas, this study evaluated a 215 L pilot-scale fixed-bed biofilm reactor (FBBR), known for its simplicity in implementation, operation, and maintenance. During the operation, an initial startup period, with the liquid fraction of fruit and vegetable waste (LF-FVW) was conducted, followed by a gradual transition to SWW, creating a co-digestion period during the substrate transition. Organic load variations (1.59, 3.35, and 4.00 kgCOD/m3·d), corresponding to flow rates of 50, 75, and 120 L/d, respectively, were implemented to address potential alterations in effluent concentration and composition in authentic rural settings. Removal rates of up to 83.69, 91.81, 87.00, and 92.00% were achieved for COD, sCOD, TS, and VS, respectively, with an average removal of 32.00% for TN, and biogas production exceeded 300 L/h at 4.00 kgCOD/m3·d. These results suggest that FBBR implementation in rural areas effectively confronts SWW treatment challenges by reducing contamination, generating biogas, and adapting to rural conditions.

Estimating release of the antibiotic metronidazole into the environment from hospital effluents and assessment of the associated ecological risk: a case study in Isfahan, Iran (2023)

Hospital effluents are important sources for the release of pharmaceuticals into the environment. Metronidazole (MTZ) is one of the most popular antimicrobial agent, widely used in veterinary and human medicine. This study aims to determine the concentrations of MTZ in the effluent of hospitals and to evaluate ecotoxicological risk for aquatic organisms. Grab samples were taken from the effluents of 15 large hospitals in Isfahan City (Iran) and MTZ concentrations were analyzed using HPLC-UV. Average daily MTZ prescriptions for patients in each hospital was also determined. MTZ was detected in effluents of all 15 hospitals in the range of 0.3 to 9.5 µg/L (mean = 4.8 ± 6.4 µg/L). A significant correlation was observed between MTZ concentration in hospital effluent and MTZ prescription as well as the hospital beds. Ecological risk assessment showed MTZ contamination of hospital effluent from 7 of 15 hospitals had median risk (risk quotient of 0.1 to 1) for green algae (Chlorella sp.) while the effluent of all hospitals had minimal risk (risk quotient <0.1) for gram-negative bacteria (Vibrio fischeri) and aquatic crustaceans (Daphnia magna). It is necessary to develop efficient treatment methods for the removal of MTZ from the hospital effluents before discharging them into the municipal wastewater systems.

Two-step polyhydroxybutyrate production from hydrogenic effluent by freshwater microalgae Coelastrella sp. KKU-P1 and Acutodesmus sp. KKU-P2 under mixotrophic cultivation

This study aimed to produce PHB using hydrogenic effluent discharged from the biohydrogen production process with freshwater microalgae including Coelastrella sp. KKU-P1, and Acutodesmus sp. KKU-P2. Batch experiments explored the influence of initial pH and hydrogenic effluent concentration, revealing optimal conditions at 10 % (v/v) effluent concentration and a pH of 6.5 for both KKU-P1 and KKU-P2. Subsequently, medium formulation and photoperiods were optimized to maximize biomass and PHB accumulation. The results showed that the optimal condition for PHB accumulation with KKU-P1 and KKU-P2 was nitrogen phosphorus (NP)-limited Bold's Basal Medium (BBM) under dark conditions. A two-step PHB accumulation in the upscale bioreactor was investigated under optimal conditions. The results showed that KKU-P1 achieved maximum PHB, protein, carbohydrate, and lipid contents of 4.57 %, 29.37 %, 24.76 %, and 13.21 %, respectively, whereas KKU-P2 achieved 6.35 %, 31.53 %, 16.16 %, and 4.77 %, respectively. Based on these findings, it appears that a mixotrophic approach under nutrient-limiting conditions is effective for PHB production in both KKU-P1 and KKU-P2 strains.

Development and application of an intelligent nitrogen removal diagnosis and optimization framework for WWTPs: Low-carbon and stable operation

Optimizing nitrogen removal is crucial for ensuring the efficient operation of wastewater treatment plants (WWTPs), but it is susceptible to variations in influent conditions and operational parameter constraints, and conflicts with the energy-saving and carbon emission reduction goals. To address these issues, this study proposes a hybrid framework integrating process simulation, machine learning, and multi-objective genetic algorithms for nitrogen removal diagnosis and optimization, aiming to predict the total nitrogen in effluent, diagnose nitrogen over-limit risks, and optimize the control strategies. Taking a full-scale WWTP as a case study, a process time-lag simulation-enhanced machine learning model (PTLS-ML) was developed, achieving R2 values of 0.94 and 0.79 for the training and testing sets, respectively. The proposed model successfully identified the potential reasons of nitrogen over-limit risks under different influent conditions and operational parameters, and accordingly provided optimization suggestions. In addition, the multi-objective optimization (MOO) algorithms analysis further demonstrated that maintaining 4–6 mg/L total nitrogen concentration in effluent by adjusting process operational parameters can effectively balance multiple objectives (i.e., effluent water quality, operating costs, and greenhouse gas emissions), achieving coordinated optimization. This framework can serve as a reference for stable operation, energy-saving, and emission reduction in the nitrogen removal of WWTPs.

Study of an electrochemical system with dual cathodes for the treatment of mariculture wastewater

The salinity properties of mariculture wastewater make it a suitable candidate for electrochemical treatment. In this study, an electro-Fenton synergistic electrocatalytic system was developed using a mixed metal oxide anode, often called Dimensionally Stable Anodes (DSA), and dual cathodes, an iron-carrying activated carbon sheet as the first cathode and a stainless-steel plate as the second cathode, to treat mariculture wastewater. The reaction conditions of the system were investigated and optimized. The chemical oxygen demand (COD) removal rate reached 100 % after 80 min under the optimal conditions: an applied voltage of 3.39 V, a plate spacing of 1.07 cm, and an aeration rate of 34.84 L·h−1. The system effectively removed COD and nitrogen from mariculture wastewater. Analyses using GC–MS, UV–visible spectroscopy, and Fourier-transform infrared spectroscopy showed that the system could degrade macromolecular organic pollutants in the wastewater. Mechanistic studies revealed that active chlorine and hydroxyl radicals play crucial roles in pollutant removal. The dynamic operation study indicated that the optimal operating conditions included a vertical water flow direction through the electrodes, and a flow rate of 10 mL·min−1. The oxidant reuse experiment determined a reflux ratio of 1:1 and a reaction time of 60 min, achieving effluent COD and NH3-N concentrations that met the primary discharge standards. The study on residual chlorine removal showed that the input amount of sodium thiosulfate was 0.36 kg, with a treatment cost of 0.32 yuan per ton of water, and the treated effluent met the discharge standards. These results provide a reference for the industrial application of electrochemical methods in treating mariculture wastewater.

Fe3+ augmentation enhancing the nitrogen and phosphorus control in denitrification biofilter based on water supply sludge: Performance and microbial characteristics

The intricate mechanisms of iron (Fe) enhancing the simultaneous nitrogen (N) and phosphorus (P) removal in the denitrification biofilter (DNBF) remain enigmatic and warrant further investigation. Fe2+ and Fe3+ were added to compare the enhancing performances and the dosage concentration was optimized in this study, and the effects of Fe3+ on microbial characteristics were elucidated furtherly. Results demonstrated that the N removal performance with Fe3+ enhancing was better than Fe2+, and the optimal FeCl3 concentration was 0.56 mg/L. The effluent concentrations of total phosphorus (TP), total nitrogen (TN), and chemical oxygen demand (COD) lowed to 0.27, 4.2, and 13.4 mg/L, respectively. Fe3+ promoted microbial richness and diversity, with Proteobacteria, Bacteroidetes and Firmicutes emerging as the advantageous phyla for N and P removal in the DNBF. Microorganisms facilitated Fe3+ reduction to enhance denitrification process, and P was predominantly removed through the precipitation formed by the interaction of Fe and P. Furthermore, Fe3+ was noted to promote functional metabolism, thereby aiding in N removal. This study can reveal the effect of Fe3+ on N removal in the DNBF, and provide a theoretical foundation for advanced N and P removal.

Solute transport in stochastic discrete fracture-matrix systems: Impact of network structure

Obtaining a comprehensive understanding of solute transport in fractured rocks is crucial for various geoengineering applications, including waste disposal and construction of geo-energy infrastructure. It was realized that solute transport in fractured rocks is controlled by stochastic discrete fracture-matrix systems. However, the impacts and specific uncertainty caused by fracture network structures on solute transport in discrete fracture-matrix systems have yet not been fully understood. In this article, we aim to investigate the influence of fracture network structure on solute transport in stochastic discrete fracture-matrix systems. The fluid flow and solute transport are simulated using a three-dimensional discrete fracture matrix model with considering various values of fracture density and size (i.e., radius). The obtained results reveal that as the fracture density or minimum fracture radius increases, the corresponding fluid flow and solute transport channels increase, and the solute concentration distribution range expands in the matrix. This phenomenon, attributed to the enhanced connectivity of the fracture network, leads to a rise in the effluent solute concentration mean value from 0.422 to 0.704, or from 0.496 to 0.689. Furthermore, when solute transport reached a steady state, the coefficient of variation of effluent concentration decreases with the increasing fracture density or minimum fracture radius in different scenarios, indicating an improvement in the homogeneity of solute transport results. The presented analysis results of solute transport in stochastic discrete fracture-matrix systems can be helpful for uncertainty management in the geological disposal of high-level radioactive waste.

A novel and cost-effective biological denitrification associated with membrane process for treating pesticide wastewater: Excellent nitrogen removal effect and higher environment benefits

A two-phase anaerobic/aerobic/integrated deoxygenated and anoxic reactor associated with membrane process, namely biological denitrification associated with membrane process (BDMP), was designed to achieving effluent TN below 10 mg/L for pesticide wastewater. For 397 days, COD, TN, NH4+−N and alkali demand were investigated under different hydraulic retention times (HRTs) compared with conventional biological treatment process (CBTP), which was composed of anoxic-anaerobic-anoxic-aerobic process. The average COD effluent concentration of BDMP and CBTP was 36.41 mg/L and 984.42 mg/L. The average TN removal efficiency of BDMP (97.3 %) was significantly higher than that of CBTP (85.6 %), and the average NH4+−N removal efficiency of BDMP was 99.3 %. The alkali demand in BDMP decreased by 11.56 %. Through calculation, similar capital cost (776.132 and 753.812 US$ × 104) and operating cost (1.69 and 1.70 US$ × 104) and superior environmental benefits (746.71 and 695.72 US$/m3·d) were seen in BDMP and CBTP.

The perfluorooctanoic acid accumulation and release from pipelines promoted growth of bacterial communities and opportunistic pathogens with different antibiotic resistance genes in drinking water

The spread of opportunistic pathogens (OPs) and antibiotic resistance genes (ARGs) through drinking water has already caused serious human health issues. There is also an urgent need to know the effects of perfluorooctanoic acid (PFOA) on OPs with different ARGs in drinking water. Our results suggested that PFOA accumulation and release from the pipelines induced its concentration in pipelines effluents increase from 0.03 ± 0.01 μg/L to 0.70 ± 0.01 μg/L after 6 months accumulation. The PFOA also promoted the growth of Hyphomicrobium, Microbacterium, and Bradyrhizobium. In addition, PFOA accumulation and release from the pipelines enhanced the metabolism and tricarboxylic acid (TCA) cycle processes, resulting in more extracellular polymeric substances (EPS) production. Due to EPS protection, Pseudomonas aeruginosa and Legionella pneumophila increased to (7.20 ± 0.09) × 104 gene copies/mL, and (8.85 ± 0.11) × 102 gene copies/mL, respectively. Moreover, PFOA also enhanced the transfer potential of different ARGs, including emrB, mdtB, mdtC, mexF, and macB. The main bacterial community composition and the main OPs positively correlated with the main ARGs and mobile genetic elements (MGE)-ARGs significantly. Therefore, PFOA promoted the propagation of OPs with different ARGs. These results are meaningful for controlling the microbial risk caused by the OPs with ARGs and MGE-ARGs in drinking water.

Surface modification of fibres using bipolar pulsed driven DBD plasma based KrCl* and XeI* exciplex sources

This work demonstrates the application of DBD plasma-based exciplex UV technology for surface modification of natural fibres. KrCl* (222 nm) and XeI* (253 nm) exciplex lamps have been developed and characterized in terms of the applied voltage, applied frequency, gas pressure, and absolute UV light intensity. The measured radiated intensities are 2.45 mW/cm2 and 1.91 mW/cm2 for 222 nm and 253 nm exciplex lamps, respectively. The change in physicochemical properties such as tensile strength, weight loss, wettability, surface morphology, and chemical composition, are evaluated using different characterization techniques ̶ like Contact Angle Goniometry, Thermogravimetric Analysis (TGA), Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy (ATR-FTIR), Field Emission Scanning Electron Microscopy (FE-SEM), and Energy Dispersive X-ray (EDX) analysis, etc. The results are compared with untreated fibres to see the effect of different doses of UV222 and UV253 on the different properties of fibres. It is inferred that the exciplex UV222 treated fibres have a higher concentration of different polar groups (− OH, − COOH, etc.). Much improvement in the dyebath ability of the natural fibre is achieved using a 222 nm exciplex light source, which reduces the dye concentration in the textile effluents and improves the dye adhesion to the fibre. It has been found that the fibre's hydrophilicity and dye bath capabilities have improved significantly.

Wastewater treatment process using immobilized microalgae.

Microalgae biomass products are gaining popularity due to their diverse applications in various sectors. However, the costs associated with media ingredients and cell harvesting pose challenges to the scale-up of microalgae cultivation. This study evaluated the growth and nutrient removal efficiency (RE) of immobilized microalgae Tetradesmus obliquus in sodium alginate beads cultivated in swine manure-based wastewater compared to free cells. The main findings of this research include (i) immobilized cells outperformed free cells, showing approximately 2.3 times higher biomass production, especially at 10% effluent concentration; (ii) enhanced organic carbon removal was observed, with a significant 62% reduction in chemical oxygen demand (383.46-144.84 mg L-1) within 48 h for immobilized cells compared to 6% in free culture; (iii) both immobilized and free cells exhibited efficient removal of total nitrogen and total phosphorus, with high REs exceeding 99% for phosphorus. In addition, microscopic analysis confirmed successful cell dispersion within the alginate beads, ensuring efficient light and substrate transfer. Overall, the results highlight the potential of immobilization techniques and alternative media, such as biodigested swine manure, to enhance microalgal growth and nutrient RE, offering promising prospects for sustainable wastewater treatment processes.

Acute toxicity of Oreochromis niloticus fingerlings exposed to effluent from Delta State University, Abraka Nigeria boys hostel

Studies on aquatic pollution are crucial for maintaining environmental health. This study assessed the toxicity of effluents from the male hostel site II at Delta State University (DELSU) on Oreochromis niloticus fingerlings. Behavioral responses and mortality rates were observed as toxicity indicators. The physicochemical characteristics of the raw effluent were evaluated and compared with standard methods. In a 96-hour static bioassay, 20 fingerlings were exposed to varying effluent concentrations: 0%, 20%, 40%, 60%, 80%, and 100%, with the experiment triplicated. Analysis showed pH (5.6), temperature (26.1°C), TDS (304 mg/L), dissolved oxygen (5.7 mg/L), chlorine (5.55 mg/L), ammonia (0.21 mg/L), and hardness (0.79 mg/L). Water analysis over 12-96 hours ranged for pH (5.45-5.62), temperature (22.50-26.30°C), TDS (61.50-237.50 mg/L), DO (4.45-6.00 mg/L), chlorine (0.84-3.98 mg/L), ammonia (0.14-0.37 mg/L), and hardness (6.52-31.93 mg/L), with no statistically significant differences (p&gt;0.05). Behavioral responses included air gulping, irregular swimming, and lack of reflex. Mortality depended on effluent concentration, with no deaths at 0%-80% but 80% mortality at 100%. Lethal times for 50% and 95% mortality at 100% concentration were 48.6 and 102.8 hours, respectively. Diluting or treating wastewater before release is necessary to prevent fish mortality in the wild.