Receiving Water Bodies Research Articles

Is flow control in a space-constrained drainage network effective? A performance assessment for combined sewer overflow reduction

Recurring combined sewer overflows (CSOs) can have a significant impact on the ecological condition of receiving water bodies. There are several structural measures, like adding retention basins and switching to low impact development solutions, that have been proposed to reduce the number of sewage overflows. Besides, several flow control strategies have been discussed in scientific literature that take advantage of the space within urban drainage networks, which is assumed to be adequate, for temporary storage. The adequacy of such storage space, however, is not a universally valid assumption as a large fraction of drainage networks frequently operate close to their design discharge. In this paper, we investigate the efficacy of flow control for a space-constrained drainage network. We employ a low-cost, heuristic real time control strategy with the use of flow control devices (FCDs) and available in-sewer space to reduce the magnitude of CSOs. We consider the performance of the proposed control strategy and discuss the effect of FCD location on CSO reduction. Our results, based on over 300 rainfall-event simulations, show that the flow control strategy using limited sewer capacity is more efficient during relatively small rainfall events, where the CSO is large enough to enable reduction using the chosen control rules. The CSO is reduced, to varying degrees, for around 80% of rainfall events with peak intensity between 10 and 20 mm h−1. For larger rainfall events, the flow control is more unstable in response to abrupt water release during control operation, which seems to be unavoidable because of the water accumulation effect and the transition to pressurized pipe flow in space-constrained networks. We also found that the flow control performance is highly sensitive to the FCD location – as it depends on the interplay of the peak rainfall intensity and the water level condition immediately upstream of the FCD. The efficacy of a location for flow control is determined by the unfilled capacity (i.e., effective in-sewer storage potential) in the pipe upstream of the FCD during the rainfall peak; furthermore, the location also has to be resistant to the water accumulation effect. Using our analysis, we substantiate two anticipated caveats to flow control strategies when the storage space is limited in a drainage network: diminished performance in CSO reduction and the appearance of additional control-related challenges, which are otherwise mitigated in more spacious networks.

Edge-of-field runoff prediction by a hybrid modeling approach using causal inference

Unforeseen runoff events cause nutrient losses that affect crop production, revenue, and contribute to deteriorated water quality, leading to harmful algal blooms and hypoxia in receiving water bodies in the Great Lakes region. To mitigate the negative impacts caused by runoff events, we developed a hybrid modeling approach by combining physics-based and statistical models to predict the occurrence and level of severity of daily runoff events, supporting agricultural producers to avoid nutrient application before significant runoff events. We chose to use the National Oceanic and Atmospheric Administration’s National Water Model (NWM) as the physical model given its flexible architecture design, technical robustness, model resolution, data availability, and wide application scale. For the statistical model, we developed a data-driven tool built from Directed Information and eXtreme Gradient Boosting (XGBoost) to estimate the occurrence and the level of severity of daily edge-of-eld (EOF) runoff events. This data-driven tool ingests a large variety of variables from NWM operational runs and translates them into the EOF runoff predictions on a daily scale in the Great Lakes region. Without calibrating the large-scale NWM for the local runoff prediction, the results show large improvements in the prediction of the occurrence and level of severity of daily EOF runoff using the hybrid physical-statistical modeling approach. Ultimately, the hybrid approach, when integrated into runoff risk decision support tools, is expected to provide dual benefits to agricultural producers and water quality, retaining more nutrients on their fields and lowering nutrient loads to water bodies during runoff events.

The Py – GC-TOF-MS analysis and characterization of microplastics (MPs) in a wastewater treatment plant in Gauteng Province, South Africa

Wastewater treatment plants (WWTPs) in South Africa, like is the case for most WWTPs around the globe albeit capable of removing substantial quantities of microplastics (MPs) and in fact, the treatments become ineffective for those plastic particles less than 100 µm. As a consequence, the receiving water bodies in which the final effluent is discharged becomes highly polluted. The present research is devoted to the analysis of the pervasive MPs in wastewaters of the treatment plant located in the Gauteng Province, South Africa using Pyrolysis – GC-TOF-MS. Based on the results, there were 23 pyrolyzate products with contributions from PVC, PA, PET and PE with abundances of 47.8%, 13.1%, 17.4% and 4.3% respectively. The remaining 17.4% could be attributed as additives in MPs. The SEM images illustrated that the MPs appeared to be inter – wined, fibrous of different thicknesses and lengths. The highly weathered MPs exhibited the rough surface which was noticeably damaged with peeled off layers presumably because of photo-oxidation during the aging process. The vibrational modes of FTIR revealed the presence of the various functional groups in the corresponding polymers of MPs. The thermal studies confirmed the presence of calcium, aluminum and silicon as residues of catalysts or flame retardants or UV stabilizers in MPs or as adsorbates resulting from the surface adsorption from the surroundings. The Py-GC-TOF-MS confirmed the identity of the various fragments related to the MPs monomers

Sewage Flow Conditions in a Hydroponic Lagoon in Terms of Quality of Treated Wastewater

The aim of this study was to analyse the impact of velocity in the hydroponic lagoon used as the 3rd stage of municipal wastewater treatment on washing out of the particles suspended in the sewage as well as settled on the bottom of the hydroponic ditch. In order to analyse the flow velocity in the lagoon, 12 cross-sections were determined at points where the speed and motion of particles can change. Wastewater samples were taken in the summer month from each of the 12 sampling points (the depth of 0.1 m) and the basic physicochemical parameters of sewage were determined (BOD5, COD, TOC, TSS, turbidity). In selected cross-sections, a granulometric analysis of particles was made to determine the characteristics of suspended solids in the wastewater flow path. Based on the analysis, it was found that velocities in the lagoon during aeration can be ten times higher (0.070 m·s−1) than those assumed by designers (0.006 m·s−1). Such a large difference means that the sedimentation conditions assumed in the project cannot be met, which may result in an increase in the total suspended solids and organic matter concentrations at the outflow to the receiving water body. During the flow through the hydroponic ditch, the highest efficiency of pollutant removal was indicated for BOD5 — 88.7% and TSS — 80%, while the COD removal occurred with the lowest efficiency — 34.1%. Improving flow conditions as designed in the hydroponic lagoon technological project may increase the efficiency of wastewater treatment at the third stage of treatment.

Performance efficiency and water quality index of a two-stage horizontal subsurface flow constructed wetland system polishing anaerobically treated brewery effluent

The disposal of untreated or partially treated brewery wastewater can cause pollution problems to the receiving water bodies. The objective of this study was to evaluate the effectiveness of a two-stage horizontal subsurface flow constructed wetland (HSSFCW) system planted with Cyperus alternifolius and Typha latifolia in polishing an up-flow anaerobic sludge blanket (UASB) reactor treating brewery effluent in Kombolcha, Northern Ethiopia. The system was integrated with the UASB reactor, and its performance efficiency was monitored for a year using standard methods. The first-order kinetic model was used to correlate the influent and effluent pollutant concentrations and estimate the areal rate constant (kA) by fitting the experimental data to the model. The HSSFCW's water quality index (WQI) and oxygen transfer rate (OTR) were also calculated. The findings showed that HSSFCW removed 89% total suspended solids (TSS), 92% chemical oxygen demand (COD), 83.6% total nitrogen (TN), 92.9% ammonium – nitrogen (NH4+ − N), 74.4% total phosphorous (TP), and 79.5% orthophosphate (PO43−). Literature comparable OTR values were obtained for each HSSFCW stage with a total OTR value of 23.5 g−2d−1. Effluent concentrations of COD, TN and NH4+ − N were reasonably correlated (R2 ≥ 0.85) to influent concentrations. The calculated kA (md-1) for TSS, COD, TN, NH4+ − N, TP, and PO43− were 0.26, 0.26, 0.11, 0.18, 0.08, and 0.08, respectively. Further polishing of the effluent with two-stage HSSFCW has shifted the WQI from a good to excellent water quality rating and thus, can be used as a sustainable polishing technique for agro-process wastewaters.

Characterization of the distribution, source, and potential ecological risk of perfluorinated alkyl substances (PFASs) in the inland river basin of Longgang District, South China

Previous studies of perfluorinated alkyl substances (PFASs) in receiving water bodies of typical industrial parks under the low-carbon development mode are scarce. In the present study, 18 PFASs were analyzed in surface water and sediment samples of the inland river basin in Longgang District in 2017. The ΣPFAS concentrations in surface water (drought and rainy periods) and sediment ranged from 15.17 to 948.50 ng/L, 11.56–561.14 ng/L, and 1.07–28.94 ng/g dw, respectively. Perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA) and perfluorobutane sulfonate (PFBS) were the dominant pollutants in surface water, with maximum concentrations of 867.68 ng/L, 288.28 ng/L, and 245.09 ng/L, respectively. Meanwhile, PFOS, perfluoroundecanoic acid (PFUdA), PFBS, and perfluorodecanoic acid (PFDA) were the major PFASs in the sediment samples, with maximum concentrations of 9.83 ng/g dw, 11.86 ng/g dw, 5.30 ng/g dw, and 5.23 ng/g dw, respectively. In addition, PFOA and PFOS resulted from similar sources in sediment and surface water samples (P < 0.05). The risk quotient value (RQ) results showed that the control of PFOS in the treatment of pollutants in the inland river basin of Longgang District deserves more attention.

Analisis Kebutuhan Lahan Dan Sarana Prasarana Pengelolaan Sampah (Studi Kasus : TPA Ngegong Kota Blitar)

The existence of waste is still a problem that affects almost all regions in Indonesia. Leachate is a liquid produced from the decomposition of waste in landfills which can seep into the ground and can contaminate groundwater and its surroundings. Until now, waste management, such as recycling waste or directly dumping it into a landfill, can be done using the Landfill method (landfilling) or an incinerator (incineration) is still needed to solve the waste problem. This discussion is to examine the impact of leachate channels on the environment, leachate management systems and land requirements. This study was conducted at the location of the Kenep Final Disposal Site in Pasuruan Regency. Therefore, efforts to manage existing leachate water are needed before discharge to a receiving water body or river. In this discussion, the leachate discharge value of 0,689 lt/dt was obtained so that the results for the dimensions of the Leachate Management Installation were obtained for the Stabilization Pool area 85.04 m², depth of 3.5 m, long 10 m, wide 8.5 m, and an efficiency of 67%. The Facultative pool area 198.43 m², depth of 3 m, long 15 m, wide 13.23 m, and an efficiency of 50%. The Maturation Pool area 198.43 m², depth of 3 m, long 15 m, wide 13.23 m and an efficiency of 50%. And it takes a widening of the area for the Kenep Final Disposal Site in Pasuruan Regency by 0.6 hectares or 6000 m².

Articles of Significant Interest in This Issue.

Methane and nitrogen have to be removed from wastewater to enable its discharge into receiving water bodies. Ammonia and methane can potentially be removed by a combination of anaerobic ammonia (anammox)- and methane (N-damo)-oxidizing microorganisms. In a wastewater treatment, these microorganisms will be exposed to oxygen. van Kessel and colleagues (e00043-21) show the simultaneous activity of aerobic and anaerobic ammonia- and methane oxidizing microorganisms in the presence of limiting amounts of oxygen. A stable community was formed, which is important for the potential application of these combined processes in wastewater treatment.

Development and Application of a SWMM-Based Simulation Model for Municipal Scale Hydrologic Assessments

There is growing interest for the installation of green stormwater infrastructure (GSI) to improve stormwater control, increase infiltration of stormwater, and improve receiving water body quality. Planning level tools are needed to inform municipal scale decisions on the type and extent of GSI to apply. Here, a modified methodology is developed for the EPA Storm Water Management Model (SWMM) to create SWMM for Low Impact Technology Evaluation (SWWM-LITE) that enables municipal scale assessment of stormwater control measure (SCM) performance with minimal input data requirements and low processing time. Hydrologic outputs of SWMM-LITE are compared to those for SWMM and the National Stormwater Calculator (SWC) to assess the performance of SWMM-LITE. Three scenarios including the baseline without SCMs and the installation of varying SCMs were investigated. Across the three scenarios, SWMM-LITE estimates of annual average hydrologic performance (runoff, infiltration, and evaporation) were within +/−0.1% of estimates from a rigorously developed SWMM model in the City of Fort Collins, CO, for an evaluation of 30 years of continuous simulation. Analysis conducted for 2 year (y), 10 y, and 100 y storm events showed less than +/−2.5% difference between SWMM and SWMM-LITE hydrologic outputs. SWC provided reasonable estimates of hydrologic parameters for the case study area, but was designed for site level analyses of performance of SCMs rather than on the municipal scale. A sensitivity analysis revealed that the most sensitive parameters were primarily consistent for the SWMM-LITE and the complete SWMM. SWMM-LITE has low input data requirements and processing time and can be applied for assessing the hydrologic performance of SCMs to inform planning level decisions.

Water, energy and climate benefits of urban greening throughout Europe under different climatic scenarios

Urban greening is an effective mitigation option for climate change in urban areas. In this contribution, a European Union (EU)-wide assessment is presented to quantify the benefits of urban greening in terms of availability of green water, reduction of cooling costs and CO2 sequestration from the atmosphere, for different climatic scenarios. Results show that greening of 35% of the EU’s urban surface (i.e. more than 26,000 km2) would avoid up to 55.8 Mtons year−1 CO2 equivalent of greenhouse gas emissions, reducing energy demand for the cooling of buildings in summer by up to 92 TWh per year, with a net present value (NPV) of more than 364 billion Euro. It would also transpire about 10 km3 year−1 of rain water, turning into “green” water about 17.5% of the “blue” water that is now urban runoff, helping reduce pollution of the receiving water bodies and urban flooding. The greening of urban surfaces would decrease their summer temperature by 2.5–6 °C, with a mitigation of the urban heat island effect estimated to have a NPV of 221 billion Euro over a period of 40 years. The monetized benefits cover less than half of the estimated costs of greening, having a NPV of 1323 billion Euro on the same period. Net of the monetized benefits, the cost of greening 26,000 km2 of urban surfaces in Europe is estimated around 60 Euro year−1 per European urban resident. The additional benefits of urban greening related to biodiversity, water quality, health, wellbeing and other aspects, although not monetized in this study, might be worth such extra cost. When this is the case, urban greening represents a multifunctional, no-regret, cost-effective solution.

Detection and molecular characterization of enteric adenovirus in treated wastewater in the Brazilian Federal District

Human enteric viruses, such as enteric adenoviruses (HAdV), are known to be involved with gastrointestinal disorders, especially acute gastroenteritis. Several studies have used HAdV as an indicator of water quality, since they are considered highly stable and widely distributed viruses in water matrices. The aim of this study was to detect and genotype HAdVs in water matrices impacted by discharges of treated effluents from wastewater treatment plants (WWTPs). Wastewater treatment plants from the sanitary system of the Brazilian Federal District were assessed in 2018 and 2019. Samples were collected upstream and downstream from discharge points for each WWTP. Viral concentration based on adsorption-elution and conventional PCR was used for molecular detection, and positive samples were sequenced for phylogenetic analysis. Pluviosity data for the period in which the samples were collected were obtained. Our results demonstrated the presence of HAdVs in 27.2% (61/224) of the samples. The positivity was significantly higher in downstream samples compared to upstream. Moreover, the HAdV positivity was higher in downstream samples collected from receiving water bodies impacted by secondary-level WWTPs in comparison with those impacted by tertiary-level WWTPs. Phylogenetic analysis demonstrated the presence of genotypes 40 and 41, with prevalence of HAdV genotype 41. Despite the predominance of HAdV-41, an increasing frequency of the HAdV-40 was associated with higher pluviosity. In conclusion, this study is the first documentation in the Brazilian Federal District dealing with the prevalence and diversity of HAdVs in several WWTP, along with their correlation with rainfall index.

N, P, and COD conveyed by urban runoff: a comparative research between a city and a town in the Taihu Basin, China.

Stormwater runoff containing various pollutants exerts adverse effects on receiving water bodies and deteriorates the urban aquatic environment. Although numerous studies have been conducted on runoff pollution, research comparing its characteristics in cities with those in towns is rare in the literature. To close this gap, the present study was conducted. The instantaneous concentrations of ammonia-N, TN, TP, and COD during the rainfall events in the town were higher than those in the city in most conditions. The outfall concentrations increased with the increase of rainfall intensity. EMCs (the average value of EMC) and CV (coefficient of variation) of TN and DTN in the town were higher than those in the city, which may lie in the differences of urban environment planning and management, road cleaning methods, garbage disposal methods, industrial enterprise, etc. On the one hand, EMCs and CV of TP in the city's industrial areas were lowest among three functional areas, while on the other hand, in the town it was in the commercial areas rather than the industrial areas that EMCs and CV were the lowest, which may be caused by the low level of economic development of small towns in China. The concentrations of COD in the town were generally higher than that in the city. Compared with the city, the correlation among COD and various forms of N was stronger in the town, which may illustrate a stronger similarity of pollutant sources in the town. According to the results, road runoff in the town contributed more to urban aquatic pollution; thus, further research should concentrate on this particular type of runoff.

PERFORMANCE OF FILTERS COMPOSED OF BANANA STALK IN SWINE WASTEWATER TREATMENT

ABSTRACT Using organic filters produced in local communities with low financial cost can reduce the environmental impacts caused by the disposal of untreated wastewater into receiving water bodies. In this study, the objective was to evaluate the efficiency of the filtration of swine wastewater (SWW) using banana stalk as an alternative material in an organic filter. SWW was applied to the organic filter and the filtered volume was converted into pore volume. Analyses of total solids, turbidity, color, total phosphorus, and total nitrogen were performed in the filter feed solution and effluent to evaluate treatment efficiency. Regression analyses were used to obtain equations in the estimation of the filtration performance in removing these variables from wastewater, with pore volume as an independent variable. The banana stalk filter did not remove total solids and color from the feed solution applied. Removal of 10–50% of SWW turbidity were obtained by the banana stalk. Banana stalk was highly efficient in removing nitrogen and phosphorus from SWW, reaching mean removals of 67% and 62%, respectively. In general, a banana stalk filter can be considered a promising alternative in the primary treatment of SWW.

Evaluating Instream Restoration Effectiveness in Reducing Nitrogen Export from an Urban Catchment with a Data‐Model Approach

AbstractUrbanization increases stormwater runoff into streams, resulting in channel erosion, and increases in sediment and nutrient delivery to receiving water bodies. Stream restoration is widely used as a Best Management Practice to stabilize banks and reduce sediment and nutrient loads. While most instream nutrient retention measurements are often limited to low flow conditions, most of the nutrient load is mobilized at high stream flows in urban settings. We, therefore, use a process‐based stream ecosystem model in conjunction with measurements at low flows and focus on estimation of stream nitrogen retention over the full streamflow distribution. The model provides a theoretical framework to evaluate the geomorphic, hydrologic, and ecological factors that are manipulated by stream restoration, and drive nitrogen retention. We set a model for a pool‐riffle sequence restored stream (190 m) in Baltimore County, Maryland and calibrated the model to the in situ measured primary production (Nash–Sutcliffe model efficiency coefficient [NSE] NSE = 0.89), respiration (NSE = 0.74), and nitrate uptake lengths (R2 = 0.88). At the daily scale, simulations showed low nitrogen retention during high flows due to high transport rates, mobilization of stored hyporheic nitrogen, and scouring of periphyton biomass. This result underscores the need to reduce contributing watershed runoff flashiness to promote aquatic nutrient cycling and retention. At monthly and yearly time scale, model predicted a higher percent reduction in summer than in winter and estimated 5.7%–9.5% of annual nitrate reductions. While the model was tested in a pool‐riffle sequence restoration design, the approach can be adapted to evaluate a range of channel restoration design characteristics, and the effects of upland watershed restoration to mitigate stormwater loading through both restored and unrestored streams.

Pineapple peel biochar and lateritic soil as adsorbents for recovery of ammonium nitrogen from human urine

Human urine is a rich source of nitrogen which can be captured to supplement the existing sources of nitrogen fertilizers thus contributing to enhanced crop production. However, urine is the major contributor of macronutrients in municipal wastewater flows resulting into eutrophication of the receiving water bodies. Herein, pineapple peel biochar (PPB), and lateritic soil (LS) adsorbents were prepared for the safe removal of ammonium nitrogen (NH4+-N) from human urine solutions. Physicochemical properties of PPB, and LS were characterized by scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS), X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA) to investigate the relationship of their properties with NH4+-N adsorption. Langmuir, Freundlich, and Dubinin-Radushkevich (D-R) isotherm models were employed to correlate the experimental equilibrium adsorption data. The effect of contact time and initial concentration of NH4+-N adsorption was also evaluated. The D-R isotherm model best described the behaviour of NH4+-N adsorption on both PPB and LS based on the coefficient of correlation values. This model showed that the adsorption of NH4+-N on both samples was a physical process with PPB and LS having mean surface adsorption energies of 1.826 × 10−2, and 1.622 × 10−2 kJ/mol, respectively. The PPB exhibited a slightly higher adsorption capacity for NH4+-N (13.40 mg/g) than LS (10.73 mg/g) with the difference attributed to its higher surface area and porosity. These values are good indicators for assessing the effectiveness of the materials for adsorption of NH4+-N from human urine.

Characterization and distribution of different phosphorus types in the agricultural areas of Daecheong Lake Watershed, South Korea.

Agricultural areas utilize various types of agrichemicals to enhance crop growth and production. As a consequence, areas treated with excessive amounts of agrichemicals become primary sources of environmental pollutants. This study was conducted to analyze the different types of phosphorus (P) in the agricultural soils in Deacheong Lake Watershed. The effects of cultivation activities in the availability of nutrients that can potentially cause eutrophication of receiving water bodies were also assessed. The total phosphorus (T-P) and phosphate (PO4-P) concentrations in the tributaries draining into the Daecheong Lake were found to be three to seven times higher than the T-P and PO4-P concentrations in Daecheong Lake. The P concentrations in the waterways exhibited significant correlations (p < 0.05) with the soil P, implying that agricultural activities may influence the water quality in Daecheong Lake. Dry field soils had higher T-P concentrations (1246.1 ± 579.9 mg/kg) as compared to paddy fields and in situ soils due to the continuous accumulation of P in the soil strata. Non-apatite inorganic phosphorus (NAI-P) was the most dominant type of P in paddy field soils, whereas organic-P had the highest fraction in dry field soils. Paddy fields can have higher potentials of contributing to eutrophication, since NAI-P is an indicator of algal-available P. T-P concentrations in agricultural soils planted with different crops follows the order: tobacco > corn > perilla > soybean > Chinese cabbage > barley > sweet potato > garlic > potato > red pepper > rice. Generally, shifts in agricultural practices can be used to assess the contribution of agricultural areas in the eutrophication potential of water bodies.

Modelling local nanobiomaterial release and concentration hotspots in the environment

Nanobiomaterials (NBMs) are a special category of nanomaterials used in medicine. As applications of NBMs are very similar to pharmaceuticals, their environmental release patterns are likely similar as well. Different pharmaceuticals were detected in surface waters all over the world. Consequently, there exists a need to identify possible NBM exposure routes into the environment. As the application of many NBMs is only carried out at specific locations (hospitals), average predicted environmental concentrations (PECs) may not accurately represent their release to the environment. We estimated the local release of poly(lactic-co-glycolic acid) (PLGA), which is investigated for their use in drug delivery, to Swiss surface waters by using population data as well as type, size and location of hospitals as proxies. The total mean consumption of PGLA in Switzerland using an explorative full-market penetration scenario was calculated to be 770 kg/year. 105 hospitals were considered, which were connected to wastewater treatment plants and the receiving water body using graphic information system (GIS) modelling. The water body dataset contained 20,167 river segments and 210 lake polygons. Using the discharge of the river, we were able to calculate the PECs in different river segments. While we calculated high PLGA releases of 2.24 and 2.03 kg/year in large cities such as Geneva or Zurich, the resulting local PECs of 220 and 660 pg/l, respectively, were low due to the high river discharge (330 and 97 m3/s). High PLGA concentrations (up to 7,900 pg/l) on the other hand were calculated around smaller cities with local hospitals but also smaller receiving rivers (between 0.7 and 1.9 m3/s). Therefore, we conclude that population density does not accurately predict local concentration hotspots of NBMs, such as PLGA, that are administered in a hospital context. In addition, even at the locations with the highest predicted PLGA concentrations, the expected risk is low.

Seasonal and spatial dynamics of selected pesticides and nutrients in a small lake catchment – Implications for agile monitoring strategies

Intensive anthropogenic pressure such as high inputs of nutrients and pesticides severely threaten most European water bodies. Small catchments ≤10 km2 are not monitored under the Water Framework Directive but play an important role in freshwater ecosystems. The high complexity in seasonal and spatial dynamics require more than a one-size-fits-all approach in water quality monitoring. Often located in rural areas with a high agricultural activity, small catchments often carry high amounts of nutrients, pesticides and their transformation products affecting drinking water resources. With a low-cost approach of a monthly sampling campaign over the course of one year combined with meaningful indicators for potential pollution sources within the catchment this study could elucidate catchment dynamics and two hotspots for pesticides and nutrients. Two different groups of pesticides were observed (I) pesticides on long-term use which were applied in high amounts over the last decades (e.g., chloridazon and its transformation products) and (II) pesticides on short-term use, newly introduced into the market. Especially transformation products of pesticides from group (I) together with nitrate showed a steady release from two fields into the receiving water bodies over the year, probably being stored in the soil layers over the years of application slowly leaching out. Pesticides from group (II) showed a strong seasonality, released from another hotspot area probably due to run-off shortly after application. Streamlining this knowledge into targeted measures and an agile monitoring strategy for the respective catchments may allow a sustainable improvement of water quality and a better ecosystem protection.

Quality by design optimization of a liquid chromatographic-tandem mass spectrometric method for the simultaneous analysis of structurally heterogeneous pharmaceutical compounds and its application to the rapid screening in wastewater and surface water samples by large volume direct injection

This study focused on the Analytical Quality by Design (AQbD) optimization of the chromatographic separation and mass spectrometric detection of a wide group of structurally heterogeneous model pharmaceutical compounds (PhCs) and transformation products (TPs), chosen to cover the challenging issues of the co-presence of compounds characterized by (i) a wide range of physicochemical properties, (ii) the same mass transitions, and (iii) different ionisation modes. Italian consumption of PhCs were also considered as election criteria of target analytes. Octadecyl and pentafluorophenyl stationary phases, acetonitrile/methanol ratios and acidity of the eluents, column temperature, initial organic phase percentage, and elution gradient were investigated by AQbD, aiming at optimizing critical resolutions, sensitivities, and analysis time. Statistically significant models were obtained in most cases with fitting and cross-validation coefficients in the ranges of 0.681-0.998 and 0.514-0.967, respectively. After optimization, the analysis of target analytes was performed in a single chromatographic run, adopting a mixed acquisition mode based on scheduled acquisition windows comprising both single polarity and continuous polarity switching. For most investigated analytes the method provided detection limits in the sub-ng/L to low ng/L range, meeting for macrolides the sensitivity requested by the “Watch List” 2018/840/EU. The optimized method was applied to the direct injection analysis of PhCs and TPs in four wastewater treatment plant (WWTP) effluents and surface water (SW) samples collected in the receiving water bodies. Absolute values of matrix effect were found to be far higher than 20% for most target analytes in most samples. Seventeen PhCs and two TPs were quantified in at least one sample, at the wide concentration range of about 1-3200 ng/L. The most occurring PhCs in both WWTP effluents and SWs were levofloxacin (202-1239 and 100-830 ng/L), furosemide (865-3234 and 230-880 ng/L), ketoprofen (295-1104 and 270-490 ng/L), and ibuprofen (886-3232 and 690-1440 ng/L).

Contribution of sewage to occurrence of phosphodiesterase-5 inhibitors in natural water

Phosphodiesterase-5 inhibitors (PDE-5i, such as Sildenafil, Tadalafil and Vardenafil, mainly prescribed to treat erectile dysfunction) and their generic drug equivalents have been widely marketed and consumed in Korea. From the concentrations detected in wastewater, we could deduce that relatively large amounts of PDE-5i were consumed without a legal prescription. Thus, PDE-5i’s presence in the environment via sewage is unavoidable, and their environmental fate within a sewage treatment plant (STP) should be evaluated. In this study, we investigated the occurrence of three PDE-5i analogs in the influent and effluent of two STPs and the receiving water bodies. The PDE-5i concentration in total reached 62 ± 12 (STP#1) and 88 ± 37 ng L−1 (STP#2) in the sewage influent; about 70% of it was Sildenafil in both STPs. However, they were hardly removed by the STPs as the removal efficiency of the STPs was less than 10% ± 5%. Therefore, the pharmaceuticals were detected in the receiving water (lower than 7 ng L−1as a total amount) and the concentration slightly increased downstream of the STPs. A simple mass balance model applied for the compounds in the STP effluent and receiving water bodies also confirmed that the discharged PDE-5i were quite persistent. Lastly, we identified temporal and regional patterns in the consumption of the drugs from daily variations of PDE-5i in the influent to these two STPs. For instance, the levels of PDE-5i in the sewage significantly increased on weekends (from Friday to Saturday), and especially in the area where adult-entertainment businesses are common. We estimated that the amount of PDE-5i consumption in this area was 31% higher than that in the area with fewer nightlife spots. Considering that they are pharmaceutically active and resistant to treatment processes within an STP, it is advised that a regular monitoring and management program for PDE-5i should be developed to prevent the discharge of the pharmaceuticals into the water environment.