Concentrated Wastewater Research Articles

Kinetics of manganese extraction from pyrolusite using reduction leaching of acidic wastewater from steel plants

ABSTRACT Acidic wastewater from steel works was selected to reduce pyrolusite. The effects of leaching parameters such as the ratio of FeCl2 to MnO2, leaching temperature, liquid–solid ratio and initial HCl concentration in acidic wastewater on the leaching rate of manganese were investigated. The results show that under the conditions including the molar ratio of FeCl2 and MnO2 ( m FeC l 2 / m Mn O 2 ) at 2.2, the leaching temperature of 363 K, a leaching time of 180 min, an L/S ratio of 11:1, and an initial HCl concentration in acidic wastewater of 2.5 mol/L, the leaching rate of manganese in pyrolusite was 97.14%. An unreacted shrinking core model was employed to explore the kinetics of manganese in pyrolusite arising from the reduction leaching of acidic wastewater from steel plants. The results imply that the rate-determining step changed in the leaching process; among which, the first stage (0–100 min) of leaching was subject to the control of interfacial chemical reactions; the second stage (100–180 min) was controlled by internal diffusion. The apparent activation energy of the two stages was 15.57 and 125.48 kJ/mol respectively, and the apparent rate equations were respectively: 1 – ( 1 – r ) 1 / 3 = 0.39 ( m FeC l 2 / m Mn O 2 ) 1.18 [ HCl ] 0.21 ( V L / M S ) 0.62 exp ( − 15.57 / RT ) t 1 – 3 [ ( 1 – r ) / ( 1 – r 1 ) ] 2 / 3 + 2 [ 1 – ( 1 – r 1 ) ( r – r 1 ) 1 / 3 ] = 2.22 × 10 16 ( m FeC l 2 / m Mn O 2 ) 5.81 [ HCl ] exp ( − 125.48 RT ) t

Wastewater-based effective reproduction number and prediction under the absence of shedding information.

Estimating effective reproduction number (Re) and predicting disease incidences are essential to formulate effective strategies for disease control. Although recent studies developed models for inferring Re from wastewater-based data, they require information on shedding dynamics. Here, we proposed a framework of Re estimation and prediction without shedding information. The framework consists of a space-state model for smoothing wastewater-based data and a renewal equation modified for wastewater-based data. The applicability of the framework was tested with simulated data and real-world data on Influenza A virus (IAV) and SARS-CoV-2 concentration in wastewater in 2022/2023 season in the USA. We confirmed the state-space model effectively fits various simulated epidemic curves and real-world data. In simulations, we found wastewater-based Re (Reww) closely aligns with instantaneous clinical Re when shedding dynamics are rapid. For more prolonged shedding, Reww approximates a smoothed Re over time. We also observed the necessary sampling frequency to trace dynamics of wastewater concentration and Reww accurately in the framework varies depending on the precision of detection methods, the epidemic status, the transmissibility of infectious diseases, and shedding dynamics. By applying our framework to real-world data, we found Reww for SARS-CoV-2 showed similar trend and values to clinically-based Re. Reww for IAV ranged from 0.66 to 1.52 with a clear peak in the winter season, which agrees with previously reported Re. We also succeeded in predicting wastewater concentration in a few weeks from available wastewater-based data. These results indicate that our framework potentially enables near real-time monitoring of approximated Re and prediction of infectious disease dynamics through wastewater surveillance, which limits the delay between infection and reporting. Our framework is useful especially for regions where reliable clinical surveillance is not available and notifiable surveillance is abolished, and can be expanded to multiple infectious diseases that have been detected from wastewater.

Adsorption performance and mechanism of MgO-loaded tobermorite for Mn2+ with high concentration in wastewater

Adsorption performance and mechanism of MgO-loaded tobermorite for Mn2+ with high concentration in wastewater

Nanofluid-peroxydisulfate integrated volumetric solar interfacial evaporation system for water evaporation and organic pollutant removal

Solar evaporation exhibits significant potential for the treatment of high-salt organic wastewater. However, it's also confronted with challenges due to the accumulation of organic pollutants and salts in the concentrated wastewater following evaporation, which compromises the long-term stability of evaporation unit and complicates subsequent treatment processes. To address these challenges, a volumetric solar interfacial evaporation (V-SIE) system by integrating Fe3O4-H2O nanofluids and peroxydisulfate (PDS) were proposed in this study. In V-SIE system, Fe3O4 magnetic nanoparticles (NPs) were prepared as solar receivers to form a volume-absorbing solar energy interface and enhance evaporation efficiency. The results show that the evaporation rate was 1.412 kg/(m2·h) and the solar efficiency reached 93.75% as the temperature rose to 57.2 ℃. Additionally, the high thermal conductivity of Fe3O4 facilitated the effective heat transfer to the fluid and provided sufficient thermal energy to activate PDS, thereby removing 99.3% of Rhodamine B (RhB). Fe3O4 NPs effectively promoted the generation of reactive species including SO4•−, •OH, O2•− and 1O2 from PDS and the four main stages including N-de-ethylation, chromophore cleavage, ring-opening, and mineralization were proposed as the possible degradation pathway of RhB. This study provides a reference for developing V-SIE system and highlights the positive effect of nanofluids in advanced oxidation processes.

Extraction of estrogenic hormones in wastewater samples by using rotating disk and modified clays with ionic liquids

Both synthetic and natural hormones—17α-ethinylestradiol (EE2), 17β-estradiol (E2), and estriol (E3)—are present in wastewater samples in concentrations typically expressed in ng L-1. These concentrations are significant, as the presence of such hormones in water sources poses risks to both living organisms and the environment. Steroidal hormones from human sources are categorized as emerging pollutants and endocrine-disrupting compounds (EDCs), which constitute a health hazard.In this study, the Rotating Disk Sorption Extraction (RDSE) method was used with modified clays incorporating ionic liquids to detect estrogenic hormones in hospital wastewater treatment plant (HWWTP) samples. Sodium montmorillonite was modified to enhance its extractive capacity by intercalating ionic liquids ([C16MIM+][anion-], where anion = Br-, OH-, or BF4-) between its interlayers. Following extraction, the concentrated analytes were measured using liquid chromatography coupled with photodiode array detection (HPLC-PDA). The method achieved absolute recoveries of 61% for EE2, 41% for E2, and 20% for E3; these recoveries were lower than those obtained with a commercial C18 sorbent. However, the technique achieved enrichment factors of 13, 23, and 32 for E3, EE2, and E2, respectively. In wastewater, the intra-disk reproducibility (RSD) was below 12%. The method also provided limits of detection and quantification in HWWTP samples of 0.18–0.42 ng mL-1 for E3, 0.15–0.37 ng mL-1 for E2, and 0.07–0.16 ng mL-1 for EE2 when using the modified adsorbents. Average concentrations in hospital wastewater were measured at 4.30, 3.85, and 7.23 ng mL-1 in the influent (before treatment) and 3.81, 1.33, and 4.00 ng mL-1 in the effluent (after treatment) for E3, E2, and EE2, respectively.

Viral load-dependent masking effect by activated sludge during the aeration process

Emission of bioaerosols from wastewater treatment processes is a significant risk for the workers involved and the residents around, but the driving factors of viral aerosol emission and are not clear. In this study, four model viruses (Phi6, MS2, PhiX174, and T7) were used to investigate the effects of activated sludge on the emission of viral aerosols. It was found that more than 95% of the viruses could be adsorbed by the activated sludge within three hours. During aeration, when the activated sludge was present, the virus-containing aerosols became larger compared to no sludge situation. This implies that some viruses were adsorbed by the sludge particles during the aerosolization. The viral aerosol concentrations in air were proportion to the virus concentrations in the sludge-free wastewater, but much lower when aerosolized from the sludge suspension. This result showed a masking effect by the sludge. However, the masking effect was gradually weakened or even disappeared, when the spiked virus concentrations were less than 107 copies/mL, which are much closer to the presence of pathogenic viruses in the real wastewater. One possible explanation could be that small sludge particles might adsorb viruses preferentially compared to large ones and could help the aerosolization of viruses. This was demonstrated by the increased emission of viral aerosols after reducing the particle size of the activated sludge by sonication. This work reveals evidence that the sludge will actually not mask the aerosolization of pathogenic viruses in the wastewater treatment plant as the concentrations of most viruses are very low, and health risks always exist.

Desferrioxamine B (DFOB) assisted nanofiltration system for the recycling of gallium from low concentrated wastewater

Gallium is classified as a technology metal as it is important for technological innovations. It is also referred to as a strategic metal, which emphasizes its economic relevance. In addition, gallium is a critical raw material that is strategically important but only available in limited quantities. However, recycling dissolved gallium from low-concentration wastewater is often not done due to the lack of suitable technologies. This research presents a membrane-based approach using the siderophore Desferrioxamine B for the recycling of gallium. Nanofiltration membranes were used to separate gallium from other metal impurities (such as arsenic). The membranes recovered about 70 % of gallium from low-concentrated synthetic wastewater. Afterward, the membranes were tested using industrial wastewater, and a similar recovery rate was observed. A model was developed to predict operation parameters that would lead to the highest recovery rate of gallium with the minimum impurities. The model showed that recycling more than 90 % of gallium from wastewater is possible using this approach. Therefore, the siderophore-assisted nanofiltration approach demonstrated in this research showed great potential for the sustainable recycling of gallium from industrial wastewater.

Study on the effects of stroke ratio, velocity ratio, and duty cycle on the diffusion characteristics of pulsed buoyant jets in crossflow

Pulsed buoyancy jet diffusion dilution is characterized by low cost and high efficiency, so it is widely used in wastewater discharge dilution projects. This study, based on three-dimensional numerical simulations, investigates the effects of stroke ratio (1.71 ≤ L/D ≤ 8.57), velocity ratio (2.4 ≤ R ≤ 12), and duty cycle (0.17 ≤ η ≤ 0.83) on the diffusion of low-frequency pulsed buoyant triple jets. A large number of simulations were conducted for each parameter, and the concentration field, vorticity field, and flow field at different sections during the initial stage of the jet were analyzed. The results reveal the evolution patterns of the vortex structure in pulsed triple buoyant jets and their diffusion characteristics. The vortex structure at the initial stage of the jet exhibits continuous vortex ring characteristics, which later evolve into a vortex street and counter-rotating vortex pair (CVP) combination structure. Meanwhile, the buoyancy effect enhances the development and diffusion of the vortex structure in both the X and Z directions. As the stroke ratio decreases, the wastewater concentration distribution becomes more concentrated, and the dynamic interaction between the jets intensifies. The increase in duty cycle enhances the interaction between the jets, significantly improving the horizontal diffusion capacity, but the vertical penetration depth is less than that of continuous jets. The Strouhal number (St) is composed of the stroke ratio, velocity ratio, and duty cycle. These three parameters control the motion state of pulsed jets in the crossflow. The established relationships and equations arising from this research offer vital reference values for predicting sewage leakage and wastewater diffusion in engineering applications, contributing substantively to the theoretical framework governing multiple buoyant jets.

Phycoremediation of rice bran oil processing wastewater and biodiesel production using green microalgae, Scenedesmus obliquus: a green approach to environmental protection and remediation.

The current study investigated the enhancement of biomass in S. obliquus, using rice bran oil processing (RBOP) wastewater in different RBOP wastewater concentrations, while also aiming to produce biofuel and treat the wastewater simultaneously. The strain was grown in Blue Green-11 (BG11) media as well as RBOP wastewater at different wastewater concentrations with distilled water at 10%, 25%, 50%, 75%, and 100% under controlled experimental settings. The study findings demonstrated a notable enhancement in the characteristics of RBOP wastewater during a 16-day growth period. The 75% RBOP wastewater concentration demonstrated superior efficacy as a growth medium for producing biomass as well as lipids, among other wastewater concentrations. Accordingly, physicochemical parameters and heavy metal percent of the RBOP wastewater were assessed. The collected biomass was employed in the production of biodiesel, and the fatty acid methyl esters (FAME) were measured, along with an assessment of its characteristics. Physicochemical analysis indicated that S. obliquus was able to effectively decrease levels of nitrate, phosphate, sulfur, and chemical oxygen demand (COD) in RBOP wastewater. The heavy metal reduction percentages for iron (Fe), zinc (Zn), nickel (Ni), copper (Cu), and arsenic (As) were 69.43%, 72.94%, 72.99%, 90.49%, and 91.5%, respectively, following treatment with S. obliquus. FTIR indicated the existence of various functional groups (including alcohol, carboxylic acid) on the surface of the microalgal biomass. The FAME profile of S. obliquus exhibited a moderate level of saturated and unsaturated fatty acid content. S. obliquus demonstrated significant phycoremediation capabilities and potential for lipid production. This study has indicated that S. obliquus is a potential candidate for the treatment of wastewater.

Pharmaceutical Wastewater Treatment Using Activated Carbon in a Fixed-Bed Column

Though beneficial for health, pharmaceuticals have emerged as persistent environmental contaminants over recent decades. Discharges from wastewater treatment plants are a primary source of these pharmaceuticals in natural water bodies, as conventional treatment methods often fail to remove them effectively. Fixed-bed columns with GRANULATED ACTIVATED CARBON (GAC) are widely used in water treatment facilities to eliminate organic micropollutants; however, their efficiency in systematically removing pharmaceutical waste from wastewater still needs to be explored. This study evaluates the performance of a GAC fixed-bed adsorption column for removing ibuprofen, paracetamol, and ciprofloxacin from wastewater, focusing on contact time as a critical parameter. Key Findings: Initial concentrations of ibuprofen, paracetamol, and ciprofloxacin in the wastewater were 0.068 mg/L, 0.08486 mg/L, and 0.068 mg/L, respectively. After 45 minutes, the column achieved removal efficiencies of 100% for ibuprofen, 92.8% for paracetamol, and 67.6% for ciprofloxacin, with no significant changes in concentrations observed at 90 minutes. These results suggest that GAC fixed-bed adsorption columns can rapidly and effectively reduce pharmaceutical concentrations in wastewater, with ibuprofen showing complete removal in under an hour. This study contributes to understanding GAC’s effectiveness in treating pharmaceutical wastewater. It highlights the potential of optimised contact time for efficient removal, underscoring its viability as an industrial treatment option. Keywords: Pharmaceutical wastewater; emerging contaminants, adsorption

Selective removal and monitoring of Pb(II) ions in wastewater using fluorescence-enhanced silicon quantum dot composites

In this study, we developed a novel composite film composed of silicon quantum dot (SiQD)-nanoSiO2-polyvinyl alcohol (PVA) (referred to as SSP). This composite film exhibits dual functionality for monitoring and removing heavy metal ions from wastewater. The composition and structure of the SSP composite film were confirmed through various techniques, such as via Fourier-transform infrared spectroscopy, thermogravimetry/differential scanning calorimetry, scanning electron microscopy SEM, and X-ray photoelectron spectroscopy. The evaluation of film adsorption performance revealed that the thermodynamic behavior of the adsorption process was consistent with the theoretical predictions of the Freundlich model. However, the adsorption kinetics were more accurately described by the Elovich model. At pH 6.0, SSP achieved a maximum adsorption capacity of 263.66 mg/g at 20 °C, as determined by the Langmuir model. Additionally, the adsorption of Pb(II) ions increased the fluorescence intensity of the composite material, enabling the monitoring of Pb(II) ion concentrations in wastewater. This composite film efficiently removed Pb(II) ions with high selectivity and sustained strong adsorption performance through five cycles, emphasizing its outstanding regeneration capability. Therefore, the proposed composite material exhibits significant potential for practical applications in wastewater treatment.

Morbidity of SARS-CoV-2 in the evolution to endemicity and in comparison with influenza

BackgroundThere are three possible SARS-CoV-2 post-pandemic scenarios: (i) ongoing severity, (ii) influenza-like severity, and (iii) a transition to an endemic disease with lesser morbidity similar to that of other human coronaviruses.MethodsTo assess a possible evolution of the pandemic under the three scenarios, we use data from the US National Covid Cohort Collaborative, CDC COVID-NET, and CDC Fluview and from the WastewaterSCAN Dashboard. We include influenza disease and treatment response as benchmark. The US National Covid Cohort Collaborative allows the quantification of viral-specific morbidity using electronic health records from 424,165 SARS-CoV-2 cases, 53,846 influenza cases, and 199,971 uninfected control subjects from 2021–2022. Evolution of hospitalization rates is estimated from the correlation between national SARS-CoV-2 and influenza hospitalization data and viral gene copies in wastewater.ResultsOur findings reveal that medically attended SARS-CoV-2 infections exhibit similar morbidity to influenza [indicative of scenario (ii)], but SARS-CoV-2 hospitalization rates are one order of magnitude lower than influenza when considering virus concentration in wastewater [indicative of scenario (iii)]. Moreover, SARS-CoV-2 displays a more favorable response to antiviral therapy.ConclusionsOur analysis confirms a rapid decline in SARS-CoV-2 morbidity as it transitions to an endemic state.

Detection and assessment of antimicrobial resistance promotion risk in the Little Akaki River wastewater.

The misuse of antimicrobial agents in healthcare and animal farming has led to their release into the environment through wastewater, contributing to the emergence of resistant bacteria. This study analyzed selected antimicrobial concentration and antimicrobial resistance (AMR) risk in the Little Akaki River wastewater. Samples collected from March to December 2019, June 2020, and August 2022 were processed using solid phase extraction with a hydrophilic-lipophilic balance (HLB) cartridge and analyzed through ultra-high-performance liquid chromatography (UHPLC) with mass spectrometry. Risk quotients (RQ) were calculated as the ratio of measured environmental concentrations (MEC) to predicted no-effect concentrations (PNEC). Ciprofloxacin concentrations ranged from 5.62 to 9.34 µg/L, cefotaxime from 1.89 to 64.79 µg/L, and sulfamethoxazole from 29.11 to 248.77 µg/L, with higher concentrations observed during the wet season. MECs for ciprofloxacin, cefotaxime, and sulfamethoxazole exceeded their PNECs (RQ > 2), indicating a high risk of resistance development. Sulfamethoxazole posed the greatest risk due to its consistently elevated levels. In contrast, erythromycin concentrations remained below the PNEC, suggesting minimal resistance risk. These findings highlight the urgent need for wastewater treatment strategies to mitigate AMR risks in aquatic environments.

Forecasting SARS-CoV-2 outbreak through wastewater analysis: a success in wastewater-based epidemiology

The COVID-19 pandemic, caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), triggered a global emergency that exposed the urgent need for surveillance approaches to monitor the dynamics of viral transmission. Several epidemiological tools that may help anticipate outbreaks have been developed. Wastewater-based epidemiology is a non-invasive and population-wide methodology for tracking the epidemiological evolution of the virus. However, thorough evaluation and understanding of the limitations, robustness, and intricacies of wastewater-based epidemiology are still pending to effectively use this strategy. The aim of this study was to train highly accurate predictive models using SARS-CoV-2 virus concentrations in wastewater in a region consisting of several municipalities. The chosen region was Catalonia (Spain) given the availability of wastewater SARS-CoV-2 quantification from the Catalan surveillance network and healthcare data (clinical cases) from the regional government. By using various feature engineering and machine learning methods, we developed a model that can accurately predict and successfully generalize across the municipalities that make up Catalonia. Explainable Machine Learning frameworks were also used, which allowed us to understand the factors that influence decision-making. Our findings support wastewater-based epidemiology as a potential surveillance tool to assist public health authorities in anticipating and monitoring outbreaks.

Effective partial nitritation of dewatered liquor from dry methane fermentation using the submerged aerobic fixed film reactor (SAFFR)

Characterized as more concentrated wastewater, the treatment of dewatered liquor from dry methane fermentation via the nitritation process was investigated in the present study. The transition from synthetic to the dewatered liquor has gone through severe deterioration: a loss of nitritation capacity and increased nitration. Several modifications were implemented: replacing the fixed beds to remove accumulated sludge and refresh the biofilm, adjusting the aeration rate based on Ammonia versus Nitrite (AvN) control, and maintaining free ammonia (FA) concentration to inhibit NOB. Through continuous monitoring and incremental adjustments, nitrite conversion rate (NCR) was gradually improved to 1.4 gN/L/d, with effluent nitrate levels below 42 mgN/L. The effluent ratio of NO2–/NH4+ fluctuated within the range of 0.96–1.41, indicating successful partial nitritation of the target wastewater for the downstream anammox process. This acclimation experience underscores the importance of early adaptation to actual wastewater and the implementation of integrated strategies to effectively suppress nitrite oxidizing bacteria (NOB).

A comparative study on the chronic responses of titanium dioxide nanoparticles on aerobic granular sludge and algal-bacterial granular sludge processes.

The chronic effects of titanium dioxide nanoparticles (TiO2 NPs) on aerobic granular sludge (AGS) and algal-bacterial granular sludge (ABGS) was examined in this study. Sequencing batch bioreactors (SBRs) and photo sequencing batch bioreactors (PSBRs) were operated with synthetic wastewater containing 0, 1, 5, 10, 20, 30, and 50mg L-1 TiO2 NPs for 10days. Nanoparticles at concentrations of 1 and 5mg L-1 did not impact nutrient removal but led to an increase in extracellular polymeric substances (EPSs), primarily in protein (PN). With increasing nanoparticle concentration, the negative effect became more pronounced, mainly in the AGS SBRs. At 50mg L-1 TiO2, chemical oxygen demand (COD), ammonia-nitrogen (NH3-N), and phosphorus (PO43-) removal decreased by 20.9%, 12.2%, and 35.1% in AGS, respectively, while in ABGS, they reached only 13.4%, 5.7%, and 14.2%. ABGS exhibited steady-state nutrient removal at 30 and 50mg L-1 TiO2 NPs after around 5days. The higher microbial activity and EPS content in the sludge, coupled with the symbiotic relationship between algae and bacteria, contributed to the higher tolerance of ABGS to nanoparticles. Finally, although nanoparticles reduced biomass in both types of bioreactors, the accumulation of TiO2 NPs in the sludge, confirmed by Energy-dispersive X-ray spectroscopy analysis, and the absence of detectable titanium concentrations in the effluent wastewater, measured by Inductively-coupled plasma mass spectrometry, may be attributed to the specific operational conditions of this study, including the relatively short operation period (10days) and high initial MLSS concentration (6g L-1).

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.

Improvement of biogas productivity from distillery wastewater by partial potassium reduction pretreatment using two-step microfiltration and nanofiltration

The main purpose of the current study was to employ filtration pretreatment to lower the K concentration in distillery wastewater (DW) from a very high level (8800 mg/L) close to severe inhibition (>12000 mg/L) to 4350 mg/L, which was in the moderate toxic range (2500–4500 mg/L) for methanogens. The filtration pretreatment system consisted of the two steps of microfiltration (MF) to remove large solid particles and nanofiltration (NF) to reduce K concentration in the retained DW. Both steps of MF and NF were operated in batch mode with continuous recirculation. The permeate of the MF step was fed to the NF unit in conjunction with different dilution ratios (dilution water volume-to-feed volume) to lower the K content in the retentate. The higher the cumulative dilution ratio, the lower the K concentration in the retentate of the NF step. However, it has to be traded off against the increasing total volume of permeate with the higher cumulative dilution ratio. Thus, at the optimum cumulative dilution ratio of 0.5:1, the DW from filtration pretreatment with a high COD value of 111500 mg/L and a low K content of 4350 mg/L was found to have significantly higher methanogenic productivities in terms of average production rate and yields of both biogas and methane with a higher optimum COD loading rate, as compared to those of the untreated DW. Moreover, the use of the two-step filtration in this investigation could significantly lower the dilution ratio as compared to the sole dilution method (0.5:1 against 2:1).

Evaluation of the Impact of Recycled Distillery Effluent on the Cultivation of Wheat and Sorghum

With increasing global water scarcity, the reuse of treated wastewater for agricultural irrigation offers a promising solution, particularly in arid regions. This study evaluates the impact of distillery wastewater from Kinmen Kaoliang Liquor Inc. (KKL) on the growth of wheat and sorghum in the Kinmen region. The field experiment applied varying proportions of KKL wastewater to assess its effects on soil properties, nutrient distribution, and crop performance. The results showed that wastewater irrigation increased soil concentrations of key nutrients, such as potassium (K), sodium (Na), magnesium (Mg), and phosphorus (P), but also raised the electrical conductivity (EC) and sodium adsorption ratio (SAR) beyond acceptable irrigation standards. K, Mg, Ca, and P primarily accumulated in the stems and grains, while Na was concentrated in the roots. However, higher wastewater concentrations negatively affected soil permeability due to Na accumulation, and elevated salinity levels led to reduced plant biomass. This study concludes that although wastewater irrigation improves nutrient availability, careful management is essential to mitigate salinity risks and ensure sustainable agricultural practices. These findings offer valuable insights into the potential of wastewater reuse in water-scarce regions and provide practical recommendations for managing associated risks.

Toxicity of selected pharmaceuticals and their mixtures to the aquatic indicators Daphnia magna and Aliivibrio fischeri.

Despite the benefits derived from the use of pharmaceuticals, these compounds are currently considered contaminants of emerging concern because of their presence and persistence in the environment. This study aimed to determine the toxicity of 27 pharmaceuticals and the interaction effects of binary mixtures of selected compounds towards two model organisms: the microcrustacean Daphnia magna and the bacterium Aliivibrio fischeri (Microtox test). Six compounds, namely polymyxin B, polymyxin E, fluoxetine, diphenhydramine, clenbuterol and ketoprofen exhibited moderate toxicity towards D. magna. Additionally, three compounds (cefotaxime, polymyxin B, polymyxin E) also showed a moderate toxic effect on A. fischeri. The comparison of such results with model estimations showed inaccuracy in the predicted data, highlighting the relevance of experimental ecotoxicological assays. The assayed mixtures contained four selected drugs of high-hazard according to their reported concentrations in wastewater and surface water (diphenhydramine, trimethoprim, ketoprofen, and fluoxetine); data revealed interactions only in the fluoxetine-containing mixtures for D. magna, while all mixtures showed interactions (mostly synergistic) for Microtox. Chronic effects on the reproduction of D. magna were observed after exposure to fluoxetine and diphenhydramine, although higher sensitivity was determined for the latter, while the mixture of these compounds (which showed acute synergy in both models) also affected the reproduction patterns. Nonetheless, all the effects described at the acute or chronic level (for individual compounds or mixtures) were determined at concentrations higher than commonly reported at environmental levels. This work provides valuable ecotoxicological information for the risk assessment of pharmaceuticals and their mixtures in the environment.