Bayesian-Based Approaches to Exploring the Long-Term Alteration in Trace Metals of Surface Water and Its Driving Forces.

Trace metal pollution poses a serious threat to the aquatic ecosystem. Therefore, characterizing the long-term environmental behavior of trace metals and their driving forces is essential for guiding water quality management. Based on a long-term data set from 1990 to 2019, this study systematically conducted the spatiotemporal trend assessment, influential factor analysis, and source apportionment of trace elements in the rivers of the German Elbe River basin. Results show that the mean concentrations of the given elements in the last 30 years were found in the order of Fe (1179.5 ± 1221 µg·L-1) ≫ Mn (209.6 ± 181.7 µg·L-1) ≫ Zn (52.5 ± 166.2 µg·L-1) ≫ Cu (5.3 ± 5.5 µg·L-1) > Ni (4.4 ± 8.3 µg·L-1) > Pb (3.3 ± 4.4 µg·L-1) > As (2.9 ± 2.3 µg·L-1) > Cr (1.8 ± 2.4 µg·L-1) ≫ Cd (0.3 ± 1.1 µg·L-1) > Hg (0.05 ± 0.12 µg·L-1). Wavelet analyses show that river flow regimes and flooding dominated the periodic variations in metal pollution. Bayesian network suggests that the hydrochemical factors (i.e., TOC, TP, TN, pH, and EC) chemically influenced the metal mobility between water and sediments. Furthermore, the source apportionment computed by the Bayesian multivariate receptor model shows that the given element contamination was typically attributed to the geogenic sources (17.5, 95% confidence interval: 13.1-17.6%), urban and industrial sources (22.1, 18.0-27.2%), arable soil erosion (24.2, 16.4-31.5%), and historical anthropogenic activities (35.2, 32.8-43.3%). The results provided herein reveal that both the hydrochemical influence on metal mobility and the chronic disturbance from anthropogenic activities caused the long-term variation in trace metal pollution.

Innovative spiral electrode configuration for enhancement of electrocoagulation-flotation.

The performance of electrocoagulation-flotation (ECF) process can profoundly be affected by the reactor design and electrode configuration. These may, in turn, influence the removal efficiency, flow hydrodynamic, floc formation, and flotation/settling characteristics. The present work aimed at developing a new spiral electrode configuration to enhance the ECF process. To do so, the impacts of parameters such as energy consumption, removal efficiency of the contaminants from industrial wastewater with a composition of turbidity, emulsified oil, and heavy metals (Si, Zn, Pb, Ni, Cu, Cr, and Cd), as well as stirring speed and foaming have been investigated. Comparison was also made between the experimental results of the new electrode configuration with the conventional rectangular cell with plate electrode configuration with the same volume and electrode surface area. The findings revealed that energy consumption of the spiral electrode configuration within the operating times of 10, 20, 30, 32, 48, and 70 min, was approximately 20% lower compared to that of the conventional ECF. Moreover, the maximum and minimum removal efficiency of 97% and 60% were obtained for turbidity and TOC for the stirring speed of 500 rpm and Reynolds number of 10,035, respectively. Finally, the formed gas bubbles tilted toward the center due to the enhanced flow hydrodynamic which resulted in substantial reduction of foam formation.

Global Trends and Drivers in Consumption- and Income-Based Emissions of Polycyclic Aromatic Hydrocarbons.

Polycyclic aromatic hydrocarbons (PAHs) are a class of the most hazardous substances. As unavoidable byproducts of petrogenic and pyrogenic processes, their emissions are dominantly linked to various economic sectors. In international trade, not only final consumption but also primary input can transfer the emissions among regions. Therefore, a long-term impact assessment of the international trade on PAH global emissions based on the final consumption and primary input could significantly benefit worldwide PAH mitigation strategies. This study investigated the changes in consumption- and income-based PAH emissions and interregional flows of worldwide regions, using the latest available data from 1999 to 2014. Results show that in 2014, 16.8 and 10.1% of global PAH emissions were transferred by consumption and primary input through international trade. Meanwhile, the production-, consumption-, and income-based emissions in most regions were decreasing. Furthermore, from the consumption-based perspective, sub-Saharan Africa surpassed China and became the largest net exporter of consumption-based emissions. From the income-based perspective, the net income-based outflows of India and the rest of Asia increased significantly, indicating the income-based emission leakage in emerging markets. From the socioeconomic perspective, emission intensity dominated the global decline in PAH emissions. As the two main factors driving the increase in emissions, the primary input structure (41%) had a larger effect than the final demand level (28%) from 1999 to 2014. Therefore, global cooperation, through the mitigation strategies of reducing emission factors and improving international trade patterns, is posited as an efficient strategy to reduce PAH pollution and related health risks.

Towards a decentralized solution for sewer leakage detection - a review.

Sewer pipelines often leak due to physical, operational, and environmental deterioration factors. Due to the hidden infrastructure of the sewer systems, leakage detection is often costly, challenging, and crucial at the city scale. Various sewer inspection methods (SIMs) have been developed and implemented at this time. This study evaluates the existing SIMs and categorizes them based on their area of impact (AoI) into three classes. Tier-one (T-I) methods, such as deterioration models and hotspot mapping, tend to grasp a broader and reliable understanding of the sewer systems' structural health and pinpoint the network sections that are more prone to leakage. As an intermediate solution, Tier-two (T-II) non-destructive methods, such as aerial thermal imagery (ATI) and electrical resistivity tomography (ERT), inspect the potential pipe clusters regardless of their material and visualize the leaked plume generated from defects and cracks. Tier-three (T-III) methods include in-pipe SIMs, such as visual and multi-sensory inspections, that can provide an in-depth understanding of the pipe and its deterioration stage. In this study, we suggest that a sustainable sewer inspection plan should include at least two SIMs belonging to different tiers to provide a dual investigation of precision and AoI, a balance between cost and time as well as an equilibrium between self-sufficiency and decentralization.

Consumption- and Income-Based Sectoral Emissions of Polycyclic Aromatic Hydrocarbons in China from 2002 to 2017.

China is the largest emitter of polycyclic aromatic hydrocarbons (PAHs) in the world. Because of their negative influences on human health, the characteristics and potential driving forces of PAH emissions should be evaluated to establish effective mitigation strategies for different economic sectors. This study is the first to quantify the embodied and enabled PAH emissions of 108 sectors in China in 2002, 2007, 2012, and 2017. The results show that the total sectoral emissions increased by 92% (from 28.0 to 53.7 kt) from 2002 to 2012 and decreased to 53.0 kt in 2017. The eight aggregated sectors had different characteristics according to their production-, consumption-, and income-based emissions. Both the embodied and enabled emission flows increased (from 13.8 to 29.2 kt and from 11.3 to 20.5 kt, respectively) with time. The influences of the major final demands and primary inputs reversed from increasing to decreasing emissions over time. In particular, the primary input structure had a stronger impact on decreasing emissions than the final demand structure. The results revealed that different mitigation policies should be applied to different sectors and that adjusting primary input behaviors might be a relatively efficient method to reduce PAH emissions.

Growth of science in activated sludge modelling - a critical bibliometric review.

In this paper, the tool of bibliometric analysis is applied to the field of activated sludge modelling and its suitability as a first step of a literature analysis is assessed. The analysis is applied to the total dataset considered as well as a time-based classification. It can be shown that this tool is very well suited to filtering the relevant authors and publications, thus enabling a subsequent visual review. The methodology presented can also be applied to sub-disciplines or other subject areas. However, the sole use of the multiple statistical and visual tools is critically questioned. Thus, misinterpretations and apparent findings can result from structural problems in the data or parameters used. Not all of the metrics used are suitable for finding relevant publications, but rather for ranking the criteria studied. However, the latter represents the most widespread application of bibliometrics. From the analysis of the keywords, it could be deduced that there has been a temporal shift from fundamental model aspects to detailed questions such as the integration of sorption and adsorption processes or anaerobic digestion. The modelling of biological phosphorus removal has also surprisingly lost a great amount of importance in the scientific literature.

Organic matter parameters in WWTP - a critical review and recommendations for application in activated sludge modelling.

This paper includes a comprehensive literature review of sludge composition data from wastewater treatment plants. 722 data sets from 249 sources were used to establish typical ratios between COD and solids-based parameters and to verify rule-of-thumb values, respectively. Confirmation of these typical ratios can also be accomplished by using biochemical composition data. It is shown that a correlation between data from proteins, lipids and carbohydrates analysis can be related to COD/VSS ratios. Finally, using the findings from the literature review, the organic and inorganic conversion factors of COD fractions in activated sludge models are adjusted to solids-based parameters. It was shown that with the adjustments of the factors and a partition of the particulate inert fraction into a fraction assigned to the influent and a fraction assigned to the endogenous products, a better agreement with the ratios of COD/VSS in the individual sludge streams can be established.

Is There a Role for Environmental and Metabolic Factors Predisposing to Severe COVID-19?

The severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) pandemic affects people around the world. However, there have been striking differences in the number of infected individuals and deaths in different countries. Particularly, within Central Europe in countries that are similar in ethnicity, age, and medical standards and have performed similar steps of containment, such differences in mortality rates remain inexplicable. We suggest to consider and explore environmental factors to explain these intriguing variations. Countries like Northern Italy, France, Spain, and UK have suffered from 5 times more deaths from the corona virus infection than neighboring countries like Germany, Switzerland, Austria, and Denmark related to the size of their respective populations. There is a striking correlation between the level of environmental pollutants including pesticides, dioxins, and air pollution such as NO2 known to affect immune function and healthy metabolism with the rate of mortality in COVID-19 pandemic in these European countries. There is also a correlation with the use of chlorination of drinking water in these regions. In addition to the improvement of environmental protective programs, there are possibilities to lower the blood levels of these pollutants by therapeutic apheresis. Furthermore, therapeutic apheresis might be an effective method to improve metabolic inflammation, altered vascular perfusion, and neurodegeneration observed as long-term complications of COVID-19 disease.

Characterizing the anthropogenic-induced trace elements in an urban aquatic environment: A source apportionment and risk assessment with uncertainty consideration.

The spatial distribution of water quality status, especially in water bodies near intensively urbanized areas, is tightly associated with patterns of human activities. For establishing a robust assessment of the sediment quality in an urban aquatic environment, the source apportionment and risk assessment of Cr, Mn, Ni, Cu, Zn, As, Cd, Hg, and Pb in sediments from an anthropogenic-influenced lake were carried out with considering uncertainties from the analysis methods, random errors in the sample population and the spatial sediment heterogeneity. The distribution analysis of the trace metals with inverse distance weighting-determined method showed that the pollutants were concentrated in the middle and southern areas of the lake. According to the self-organizing map and constrained positive matrix factorization receptor model, agricultural sources (24.8%), industrial and vehicular sources (42.5%), and geogenic natural sources (32.7%) were the primary contributors to the given metals. The geogenic natural had the largest random errors, but the overall result was reliable according to the uncertainty analysis. Furthermore, the stochastic contamination and ecological risk models identified a moderate/considerable contamination level and a moderate ecological risk to the urban aquatic ecosystem. With consideration of uncertainties from the spatial heterogeneity, the contamination level of Hg, and the ecological risk of Cd in had a 20-30% probability of the increase.

Meshness of sewer networks and its implications for flooding occurrence.

Understanding the factors that affect the occurrence of failures in urban drainage networks (UDNs) is a key concept for developing strategies to improve the reliability of such systems. Although a lot of research has been done in this field, the relationship between UDN structure (i.e. layout) and its functional failures is still unclear. In this context, the present study focuses first on determining which are the most common sewer layout topologies, based on a data set of 118 UDNs, and then on analyzing the relationship between these and the occurrence of node flooding using eight subnetworks of the sewer system of Dresden, Germany, as a study case. A method to 'quantify' the topology of a UDN in terms of similarity to a branched or meshed system, referred to as Meshness, is introduced. Results indicate, on the one hand, that most networks have branched or predominantly branched topologies. On the other hand, node flooding events in networks with higher Meshness values are less likely to occur, and have shorter durations and smaller volumes than in predominantly branched systems. Predominantly meshed systems are identified then as more reliable in terms of flooded nodes and flooding volumes.

The influence of heavy metals in road dust on the surface runoff quality: Kinetic, isotherm, and sequential extraction investigations.

This study examines the adsorption and desorption characteristics of heavy metals in road dust (RD) for the aspect of integrated stormwater management. The chemical fractionations of Cu, Zn, Ni, and Cd were determined by a three-step sequential extraction protocol. Pseudo-first-order and Pseudo-second-order kinetic models, along with Langmuir, Freundlich, and Temkin isotherms were adopted to simulate the batch experimental data. The proportional shift of metals' chemical fractionations in original RD, adsorption equilibrium, and desorption equilibrium were determined. Results show that RD has a remarkable affinity to adsorb heavy metal within a short time. The adsorption processes were well described by the Pseudo-second-order kinetic model (R2 = 0.98-0.99) and Freundlich isotherm (R2 = 0.89-0.98) for most of the given metals indicating that the chemical adsorption was probably the rate-controlling step and the binding energy for each site was not identical. The maximum adsorption capacities for Cu, Cd, Zn, and Ni were 6300 mg kg-1, 5800 mg kg-1, 4000 mg kg-1, and 3200 mg kg-1, respectively. A linear fit to the equilibrium pH and the total amounts of the adsorbed metals indicates a strong pH-dependent adsorption. According to the proportional shift of metals' chemical fractionations during the adsorption and desorption processes, the exchangeable fractions of heavy metals in RD were irreversible. It suggests that a portion of the surface sites of RD would be not exchangeable once it was occupied.

A Review of Surfactant Role in Soil Clogging Processes at Wastewater Exfiltration Locations in Sewers.

Wastewater contains significant sources of pollutants and contaminants. often the failure of a pipe, inadequate sealing or corrupt pipe-connections cause the loss of raw sewage, which percolates into the nearby soil. As a consequence, a colmation layer in conjunction with soil clogging is developing, which regulates the exfiltration rate. Recently, literature has emerged that offers findings about the effects of wastewater surfactants on the change of physical properties of the soil. A survey of published literature in this field provides information highlighting the influential mechanisms of surfactants in soil clogging through physical, chemical and biological processes. Therefore, to provide a comprehensive approach, this review describes the adsorption mechanisms of surfactants on organic and inorganic particles, at gas-bubbles and at biomass. We also provided our own input to the description of the adsorption of surfactants at fluid/fluid and fluid/solid interfaces in porous media associated with the clogging process.

A black-box model for generation of site-specific WWTP influent quality data based on plant routine data.

This paper presents a simple method for the generation of continuous influent quality datasets for wastewater treatment plants (WWTPs) that is based on incomplete available routine data, only, without referring to any further measurement. In the approach, Weibull-distributed random data are fitted to the available routine data, such that the resulting distribution of influent quality data shows the identical statistical characteristics. Beside the description of the method, this paper contains a comprehensive analysis of robustness and universality of the approach. It is shown that incomplete datasets with only 10% remaining influent quality data can be filled with this method with nearly the same statistical parameters as the original data. In addition, the use with datasets of different WWTP plants sizes results always in a good agreement between original and filled datasets.

Quantitative measurement and control of optical Moiré pattern in an autostereoscopic liquid crystal display system.

A quantitative description of an optical moiré pattern produced in an autostereoscopic liquid crystal display system is proposed using a contrast sensitivity function. The numerical simulation, carried out in the spatial frequency domain, is applied to a directional backlit, spatially and temporally hybrid controlled display system. The moiré pattern produced from the superimposed binary optical components is examined systematically, and the results show that the visibility of the moiré pattern can be manipulated with proper grating settings. Good agreement between experiment and simulation demonstrates that the proposed theory can be applied as a design guideline to remove the moiré patterns occurring in an autostereoscopic display system.

The chemical fractionation and potential source identification of Cu, Zn and Cd on urban watershed.

This study showcases the chemical fractionation and primary source identification of Cu, Zn and Cd in road-deposited sediment. Results show that Zn and Cd were identified as easily mobilised and biologically available metals that pose high risks to the receiving aquatic environments. However, Cu was released in substantial amounts only under relatively extreme conditions. With the assistance of principal component analysis and chemical fractionation, two primary contributors to heavy metals in road-deposited sediment were tentatively identified as vehicle-related sources (especially, auto brake pad erosion for Cu and tyre debris for Zn) and atmospheric deposition (especially for Cd).

Assessing antibiotic resistance of microorganisms in sanitary sewage.

The release of antimicrobial substances into surface waters is of growing concern due to direct toxic effects on all trophic levels and the promotion of antibiotic resistance through sub-inhibitory concentration levels. This study showcases (1) the variation of antibiotics in sanitary sewage depending on different timescales and (2) a method to assess the antibiotic resistance based on an inhibition test. The test is based on the measurement of the oxygen uptake rate (OUR) in wastewater samples with increasing concentrations of the selected antibiotic agents. The following antibiotics were analysed in the present study: clarithromycin (CLA) was selected due to its high toxicity to many microorganisms (low EC50), ciprofloxacin (CIP) which is used to generally fight all bacteria concerning interstitial infections and doxycyclin (DOX) having a broad spectrum efficacy. Results show that CLA inhibited the OUR by approximately 50% at a concentration of about 10 mg L⁻¹, because Gram-negative bacteria such as Escherichia coli are resistant, whereas CIP inhibited about 90% of the OUR at a concentration equal to or greater than 10 mg L⁻¹. In the case of DOX, a moderate inhibition of about 38% at a concentration of 10 mg L⁻¹ was identified, indicating a significant antibiotic resistance. The results are consistent with the corresponding findings from the Clinical and Laboratory Standards Institute. Thus, the presented inhibition test provides a simple but robust alternative method to assess antibiotic resistance in biofilms instead of more complex clinical tests.

High-quality autostereoscopic display with spatial and sequential hybrid control.

A novel design of an autostereoscopic display system with full resolution, low crosstalk, and weak Moiré pattern is presented. The system involves the usage of an LED backlight array and a liquid crystal display (LCD) panel, in conjunction with a Fresnel lens array, to form a 3D optical image system. The finer temporal synchronization is made possible with a dynamic synchronized backlight, so that the scanning of the LCD is in phase with the backlight array. The systematic optimization presents a full HD, or even an ultra HD, display for a single left or right channel. The achieved minimum systematic crosstalk is 2.64%, a sufficiently low value reported so far with an autostereoscopic system.

The adaptation of nitrifying microorganisms to inhibiting substances at meso- and psychrophilic temperature conditions.

This paper deals with adaption capacity of nitrifiers to allylthiourea (ATU) as a model inhibitor at two temperature levels. Nitrifying communities were developed at 15 (BM15) and 30 °C (BM30). The activity of the nitrifiers was determined by using short-time respiration (STR) tests, oxygen monitoring and in-situ measurements. The oxygen monitoring provided information about the temperature-dependent time delay between the dosage of NH4(+)-N or ATU and reaching its characteristic level of effect. The greatly scattered results from the STR tests for BM15 were thus explained by the time delay, which was two to three times higher than for BM30. Furthermore, combining the results of oxygen-monitoring and in-situ measurements it can be stated that an adaption to ATU at psychrophilic temperature conditions was not achieved, whereby up to 40% of nitrification was sustained for BM30 at an ATU-concentration over 7 mg/l. The nitrification by BM15 did not start until ATU was degraded to 1-2 mg/l, the typical inhibition concentration for ATU. Hence, the results indicate a population drift to adapted nitrifiers at mesophilic conditions and ATU-degrading microorganisms at psychrophilic temperature conditions, which can have a considerable influence on domestic wastewater treatment in cold climates receiving industrial effluents.

Investigating non-point pollution mitigation strategies in response to changing environments: A cross-regional study in China and Germany.

Climate change and urbanization have altered regional hydro-environments. Yet, the impact of future changes on the pollution risk and associated mitigation strategies requires further exploration. This study proposed a hydraulic and water-quality modeling framework, to investigate the spatiotemporal characteristics of pollution risk mitigation by low impact development (LID) strategies under future Representative Concentration Pathways (RCP) and Shared Socioeconomic Pathways (SSP) scenarios. Results demonstrated that the LID strategies exhibited an effective performance of pollutant removal in the current hydro-environment, with the removal rates ranging from 33% to 56%. In future climate and urbanization scenarios, the LID performance declined and turned to be uncertain as the greenhouse gas (GHG) emissions increased, with the removal rates ranging from 12% to 59%. Scenario analysis suggested that the LID performance was enhanced by a maximum of 73% through the diversified implementation of LID practices, and the performance uncertainty was reduced by a maximum of 67% through the increased LID deployment. In addition, comparative analysis revealed that the LID strategies in a well-developed region (Dresden, Germany) were more resilient in response to changing environments, while the LID strategy in a high-growth region (Chaohu, China) exhibited a better pollutant removal performance under low-GHG scenarios. The methods and findings in this study could provide additional insights into sustainable water quality management in response to climate change and urbanization.

Regional and temporal differences in the relation between SARS-CoV-2 biomarkers in wastewater and estimated infection prevalence - Insights from long-term surveillance.

Wastewater-based epidemiology provides a conceptual framework for the evaluation of the prevalence of public health related biomarkers. In the context of the Coronavirus disease-2019, wastewater monitoring emerged as a complementary tool for epidemic management. In this study, we evaluated data from six wastewater treatment plants in the region of Saxony, Germany. The study period lasted from February to December 2021 and covered the third and fourth regional epidemic waves. We collected 1065 daily composite samples and analyzed SARS-CoV-2 RNA concentrations using reverse transcription-quantitative polymerase chain reaction (RT-qPCR). Regression models quantify the relation between RNA concentrations and disease prevalence. We demonstrated that the relation is site and time specific. Median loads per diagnosed case differed by a factor of 3-4 among sites during both waves and were on average 45 % higher during the third wave. In most cases, log-log-transformed data achieved better regression performance than non-transformed data and local calibration outperformed global models for all sites. The inclusion of lag/lead time, discharge and detection probability improved model performance in all cases significantly, but the importance of these components was also site and time specific. In all cases, models with lag/lead time and log-log-transformed data obtained satisfactory goodness-of-fit with adjusted coefficients of determination higher than 0.5. Back-estimation of testing efficiency from wastewater data confirmed state-wide prevalence estimation from individual testing statistics, but revealed pronounced differences throughout the epidemic waves and among the different sites.