1,720,968 research outputs found
Disinfection by peracetic acid: influence of inorganic and organic compounds
No full textThe disinfection effectiveness of peracetic acid (PAA) for wastewater applications has been extensively documented; however, PAA decays rapidly in water solution, depending on the water matrix characteristics. Guarantying a proper disinfectant dose is fundamental for the design of a disinfection process, therefore modeling PAA decay as a function of wastewater characteristics is crucial. The aim of this study was to assess PAA consumption in multi-component solutions reflecting realistic situations of a final effluent of a wastewater treatment plant (WWTP) under controlled conditions. Two experimental plans, one for inorganics and another one for organics, were defined using the statistical method of Design of Experiments (DoE), which allowed evaluating the effect of each compound or their interaction on PAA decay. Experiments were performed at laboratory-scale for PAA concentrations between 2-10 mgPAA/L and linear least-square regressions were used to interpolate two models based on the compounds that displayed an effect on PAA decay
Predicting long-term pharmaceutical concentrations during sewer overflows using a census data driven model
Full text linkA new modelling framework, which combines census and georeferenced data with a mechanistic storm water model, was developed to predict concentration dynamics of pharmaceuticals (PhACs) during overflow events. The model was verified with measurements and used to perform a long-term (1 year) risk assessment in a small urban catchment in Switzerland. Results show that census and georeferenced data are useful information that can be used as new type of model inputs to correctly predict PhACs concentration during combined sewer overflow (CSO) events
Modelling the fate of micropollutants in the water cycle at urban and peri-urban scale – An integrated perspective towards the impacts of water reuse
Full text linkAn integrated model was developed, calibrated and validated to predict the fate of micropollutants (MPs) and the human health risks that these substances pose when wastewater is reused for agricultural purposes. Results showed that pharmaceuticals (e.g., the anti-inflammatory drug paracetamol) can form during in-sewer transit from other metabolites and posing a potential risk (Hazard Quotient for infants = 10-2) if wastewater is not treated before irrigation. The model can represent a relevant decision-support tool to plan barriers for reducing the risk associated to MP
A statistical assessment of micropollutants occurrence, time trend, fate and human health risk using left-censored water quality data
Full text linkIn recent years, the presence of micropollutants in drinking water has become an issue of growing global concern. Due to their low concentrations, monitoring databases are usually rich in censored data (e.g. samples with concentrations reported below the limit of quantification, LOQ) which are typically eliminated or replaced with a value arbitrarily chosen between 0 and LOQ. These conventional methods have some limitations and can lead to erroneous conclusions on: presence of micropollutants in the source water, treatment efficiencies, produced water quality and associated human health risk. In this work, an advanced approach, based on Maximum Likelihood Estimation method for left-censored data (MLELC), was applied on monitoring data of 19 contaminants (metals, volatile organic compounds, pesticides and perfluorinated compounds) in 5362 groundwater (GW) and 12,344 drinking water (DW) samples, collected from 2012 to 2017 in 28 drinking water treatment plants in an urbanized area. This study demonstrates the benefits of MLELC method, especially for high percentages of censored data. Data are used to build statistical distributions which can be effectively used for several applications, such as the time trend evaluation of GW micropollutant concentrations and the estimation of treatment removal efficiency, highlighting the adequacy or the need for an upgrade. Moreover, the MLELC method has been applied to assess the human health risk associated with micropollutants, indicating the high discrepancy in the estimations obtained with conventional methods, whose results do not follow precautionary or sustainability criteria
Predicting the fate of pharmaceuticals in integrated urban wastewater systems
No full textA new category of substances, Pharmaceutical Active Compounds (PhACs), has been detected in different parts of integrated urban wastewater and stormwater (IUWS) systems. PhACs are characterized by different fate processes compared to those included in existing MP (MicroPollutants) fate modelling libraries. Thus, existing modelling tools cannot predict the fate of PhACs, and it is not possible to estimate the human and environmental risk due to their discharge in natural water. In this work a dynamic model library was developed to enable the simulation of PhACs across different IUWS elements (sewers, wastewater treatment plants, receiving water bodies). The model performance was assessed by simulating the fate of four PhACs in two different IUWS systems, where measurements were available. Model prediction capability was good, highlighting how the model can be a valuable support tool for a sustainable management of water in urban areas
Modelling the fate of micropollutants in integrated urban wastewater systems: Extending the applicability to pharmaceuticals
No full textPharmaceutical active compounds (PhACs) are a category of micropollutants frequently detected across integrated urban wastewater systems. Existing modelling tools supporting the evaluation of micropollutant fate in such complex systems, such as the IUWS_MP model library (which acronym IUWS stands for Integrated Urban Wastewater System), do not consider fate processes and fractions that are typical for PhACs. This limitation was overcome by extending the existing IUWS_MP model library with new fractions (conjugated metabolites, sequestrated fraction) and processes (consumption-excretion, deconjugation). The performance of the extended library was evaluated for five PhACs (carbamazepine, ibuprofen, diclofenac, paracetamol, furosemide) in two different integrated urban wastewater systems where measurements were available. Despite data uncertainty and the simplicity of the modelling approach, chosen to minimize data requirements, model prediction uncertainty overlapped with the measurements ranges across both systems, stressing the robustness of the proposed modelling approach. Possible applications of the extended IUWS_MP model library are presented, illustrating how this tool can support urban water managers in reducing environmental impacts from PhACs discharges
Risk assessment of contaminants of emerging concern in the context of wastewater reuse for irrigation: An integrated modelling approach
Full text linkDirect reuse of reclaimed wastewater (RWW) in agriculture has recently received increasing attention as a possible solution to water scarcity. The presence of contaminants of emerging concern (CECs) in RWW can be critical, as these chemicals can be uptaken in irrigated crops and eventually ingested during food consumption.In the present study, an integrated model was developed to predict the fate of CECs in water reuse systems where RWW is used for edible crops irrigation. The model was applied to a case study where RWW (originating from a municipal wastewater treatment plant) is discharged into a water channel, with subsequent irrigation of silage maize, rice, wheat and ryegrass. Environmental and human health risks were assessed for 13 CECs, selected based on their chemical and hazard characteristics. Predicted CEC concentrations in the channel showed good agreement with available measurements, indicating potential ecotoxicity of some CECs (estrogens and biocides) due to their limited attenuation. Plant uptake predictions were in good agreement with existing literature data, indicating higher uptake in leaves and roots than fruits. Notably, high uncertainties were shown for weakly acidic CECs, possibly due to degradation in soil and pH variations inside plants. The human health risk due to the ingestion of wheat and rice was assessed using the threshold of toxicological concern and the hazard quotient. Both approaches predicted negligible risk for most CECs, while sulfamethoxazole and 17α-ethinylestradiol exhibited the highest risk for consumers. Alternative scenarios were evaluated to identify possible risk minimization strategies (e.g., adoption of a more efficient irrigation system)
Powdered activated carbon as a tertiary treatment for pharmaceuticals and polycyclic musk fragrances removal from domestic wastewaters
No full textPharmaceuticals and Personal Care Products (PPCPs), such as polycyclic musk fragrances (PMFs), are a heterogeneous and commonly-used group of chemicals. Discharges of wastewater treatment plants (WWTPs), not optimized for the removal of these persistent compounds, can be relevant sources of PPCPs for the aquatic environment. PPCPs are biologically active and may pose a risk for human health and the environment. Among EU Member States, Italy registered the highest consumption of PMFs, with a consequent release in large amounts into the aquatic environment.
Usually, to improve the removal of organic micropollutants from wastewaters, different advanced treatments may be applied. Among them, technologies based on powdered activated carbon (PAC) adsorption as additional removal process emerged in recent years due to their effective performance.
The aim of our study, carried out within the framework of PerFORMWATER 2030 project co-founded by Regione Lombardia, was to evaluate the application of PAC in an Actiflo® Carb (patented Veolia technology) pilot plant for the removal of PPCPs in a WWTP located in northern Italy. Since removal efficiency depends on different parameters, including characteristics and dosed amount of PAC, adsorbate-adsorbent contact time, adsorbent retention time, molecular structure and properties of contaminants, concentration of organic matter in wastewater, an extensive experimental campaign was performed for assessing the influence of operating conditions and wastewater characteristics. In detail, following ranges of operating conditions were studied on two types of PAC: PAC dosage 5-20 mg/L, system PAC concentration 0.2-1 g/L, wastewater flowrate 6-9 m3/
Application of a model for supporting risk assessment of emerging contaminant in the context of wastewater reuse for irrigation
Full text linkAbout 17% of the European territories suffer from water scarcity. The situation is expected to worsen over the next years, with potentially severe socio-economic implications. Recently, EU member states agreed that agricultural reuse of reclaimed urban wastewater should be enhanced whenever this is safe, leading to the proposal of minimum requirements for safe reuse [1]. The proposal also recognized the need of including in the risk assessment (where relevant) contaminants of emerging concern, whose threat for environment and human health is well recognized. Given the general lack of measurements and the challenges inherent to field monitoring, integrated chemical fate models represent valuable tools to (i) predict exposure concentrations (for assessing the current risk) and (ii) to evaluate alternative scenarios (i.e. identify risk minimization strategies). However, these models are usually applied within the boundaries of urban areas or for hypothetical wastewater reuse scenarios [2], lacking significant validation for real cases. In this study, an integrated dynamic model was developed and tested for a highly urbanized area in northern Italy, where treated municipal wastewater is discharged into an irrigation canal. Calibration and validation were performed at different locations and risk indicators were calculated to assess environmental and human health safety associated to the exposure to several emerging contaminants
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