Leonor Amaral - Profile on Academia.edu (original) (raw)
Papers by Leonor Amaral
Effects of landfill age, climate, and size on leachate from urban waste landfills in Portugal: A statistics and machine learning analysis
Waste Management
Evaluation of Circular Performance Models in Wastewater Treatment Plants: Portugal Case-Study
Lecture notes in civil engineering, 2024
In an increasing water scarcity and climate-vulnerable global context, treated wastewater represe... more In an increasing water scarcity and climate-vulnerable global context, treated wastewater represents a vital alternative water source, thereby enhancing resource sustainability. Despite its potential, only roughly 2.5 % of the treated wastewater is reused in the European Union, with Portugal's reuse rate being only 1.2 % in 2022. Considering this framework, this study evaluates the feasibility of increasing wastewater reuse in Portugal by focusing on the Tagus River and Ribeiras do Oeste Basins. The regional assessment identified eight key wastewater treatment plants (WWTP) with significant potential for irrigation reuse in the agriculture and tourism sectors. Analysing costs, quality requirements, and technological options, this study considered five treatment lines, incorporating filtration and disinfection methods. The findings indicate that reclaimed water costs may range from 0.02€/m3 to 0.83€/m3, being competitive with other water sources and significantly lower than desalination processes (up to 1.66€/m3). Distribution investments and energy consumption are primary cost drivers, suggesting a relocation of WWTP closer to end-users as a cost-saving strategy. The proposed reuse projects could quadruple regional reuse rates and double the national rate, mitigating water needs for over 2000 ha of agricultural land and golf courses. This study underscores the importance of treated wastewater reuse in addressing water scarcity, advocating for WWTP decentralisation, strategic investments and policy interventions to achieve cost-effective goals. The methodologies and insights presented offer valuable guidance for other regions facing similar challenges, promoting a paradigm shift towards circular water resource management.
Energy Procedia, Oct 1, 2017
District heating networks are commonly addressed in the literature as one of the most effective s... more District heating networks are commonly addressed in the literature as one of the most effective solutions for decreasing the greenhouse gas emissions from the building sector. These systems require high investments which are returned through the heat sales. Due to the changed climate conditions and building renovation policies, heat demand in the future could decrease, prolonging the investment return period. The main scope of this paper is to assess the feasibility of using the heat demand-outdoor temperature function for heat demand forecast. The district of Alvalade, located in Lisbon (Portugal), was used as a case study. The district is consisted of 665 buildings that vary in both construction period and typology. Three weather scenarios (low, medium, high) and three district renovation scenarios were developed (shallow, intermediate, deep). To estimate the error, obtained heat demand values were compared with results from a dynamic heat demand model, previously developed and validated by the authors. The results showed that when only weather change is considered, the margin of error could be acceptable for some applications (the error in annual demand was lower than 20% for all weather scenarios considered). However, after introducing renovation scenarios, the error value increased up to 59.5% (depending on the weather and renovation scenarios combination considered). The value of slope coefficient increased on average within the range of 3.8% up to 8% per decade, that corresponds to the decrease in the number of heating hours of 22-139h during the heating season (depending on the combination of weather and renovation scenarios considered). On the other hand, function intercept increased for 7.8-12.7% per decade (depending on the coupled scenarios). The values suggested could be used to modify the function parameters for the scenarios considered, and improve the accuracy of heat demand estimations.
Water, 2016
To improve nutrient removal, a full-scale hybrid constructed wetland (CW) consisting of pre-treat... more To improve nutrient removal, a full-scale hybrid constructed wetland (CW) consisting of pre-treatment units, vertical-baffled flow wetlands (VBFWs), and horizontal subsurface flow wetlands (HSFWs) was installed in August 2014 to treat sewage wastewater. Artificial aeration (AA) was applied continuously in the VBFW stage to improve the aerobic condition in the hybrid CW. Water samples were collected and analyzed twice a month between the period of August 2015 and July 2016. The results suggest that this new hybrid CW can achieve a satisfactory reduction of chemical oxygen demand (COD), ammonium nitrogen (NH 4 +-N), total nitrogen (TN), and total phosphorus (TP) with average removal rates of 85% ± 10% (35% ± 19 g/m 2 per day), 76% ± 18% (7% ± 2 g/m 2 per day), 65% ± 13% (8% ± 2 g/m 2 per day), and 65% ± 21% (1 g/m 2 per day), respectively. AA significantly improved the aerobic condition throughout the experimental period, and the positive influence of AA on nitrogen removal was found to be higher during summer that during winter. A significant positive correlation between water temperature and nutrient removal (p < 0.01) was observed in the system. Overall, this study demonstrates the application of AA in a full-scale hybrid CW with satisfactory nutrient removal rates. The hybrid CW system with artificial aeration can serve as a reference for future applications areas where land availability is limited.
Journal of Water and Climate Change, 2021
The presence of salt water from the Tagus Estuary has been identified in the influent at Barreiro... more The presence of salt water from the Tagus Estuary has been identified in the influent at Barreiro/Moita Wastewater Treatment Plant (WWTP), Portugal. The intrusion occurs throughout damaged sections and direct vectors in the wastewater collection system, during high tide levels, changing the wastewater characteristics and impacting the WWTP process. This study designed models to quantify this problem, enabling more effective countermeasures within the right timing. The proposed models estimate the average volume of salt water and sulfate () load for each high tide period. The laboratory results show strong correlations between the influent electrical conductivity (EC) and percentage of salt water in WWTP inflow (0.9909), and between EC and concentration in WWTP influent (0.9797). The forecast models also show good correlation between the high tide levels with volume of salt water (0.9145) and load (0.9162) entering the system. Considering the total monthly inflow, the highest percent...
Water Practice and Technology, 2020
Salt water from the Tagus Estuary has been identified in the influent at Barreiro/Moita Wastewate... more Salt water from the Tagus Estuary has been identified in the influent at Barreiro/Moita Wastewater Treatment Plant (WWTP), Portugal. The saltwater intrusion occurs during high tide levels in the estuary throughout damaged sections and direct vectors in the sewer network, changing the wastewater characteristics impacting the WWTP processes. This work has designed a methodology to assess from which tide level in the Tagus Estuary saltwater intrusion occurs in the sewer network by measuring WWTP influent's electric conductivity (EC). The methodology identifies saltwater intrusion for tide levels higher than 3.10 m, increasing significantly for tide levels higher than 4.00 m. During this study, 86% of the days registered at least one high tide level higher than 3.10 m, and 8% higher than 4.00 m, demonstrating a considerable occurrence of saltwater intrusion in the system with a tendency to increase due to the mean sea level rise registered in the Tagus Estuary. To prevent it, it is ...
Microplastics from Wastewater Treatment Plants—Preliminary Data
Springer Water, 2017
Wastewater treatment plants (WWTIP) are a potential source of microplastics [1,2]. Several types ... more Wastewater treatment plants (WWTIP) are a potential source of microplastics [1,2]. Several types of microplastics, namely microbeads, fibres and fragments, were analysed in two WWTP effluent serving different Portuguese communities. A bigger station treating mixed domestic and industrial wastewater averaging 18000 m day and a smaller station with treating mostly domestic wastewater averaging 7250 m day. A total of 6065 microplastics were observed in 5,5 litres of wastewater sampled. 90% of the microplastics analysed were fragments and 88% were collected from treated effluent (1687 items in average per litre). Fibres presented a higher percentage in the affluent (88%), comparing to treated effluent (12%). Regarding sizes, microplastics with less than 0, 5 mm were the most representative in both WWTP. Fibres with 1 to 2 mm were more common. This study intends to contribute with a standardized methodology to analyse microplastics in wastewater, from sampling to identification, measuring and handling processes in the laboratory.
Journal of Ecological Engineering, 2020
An urban wastewater treatment system was developed in Portugal for posterior in situ feasibility ... more An urban wastewater treatment system was developed in Portugal for posterior in situ feasibility testing at the Bulgarian Antarctic Base, using its domestic wastewater. The aim of this system was to develop a low cost, integrated approach for wastewater treatment and production of nutrient solutions (NS) for hydroponic cultivation of lettuce (Lactuca sativa var. crispa) in Antarctic stations, or any other place where the lack of resources and logistical hardships make the wastewater treatment and reuse impractical. The wastewater treatment system consisted in manual agitation lime chemical precipitation (LCPm) and effluent natural neutralization (NN) by atmospheric CO 2 carbonation reactions (with and without air injection). The resulting effluent/NS had macronutrient values (nitrogen and phosphorous) for the hydroponic cultivation of lettuce below the values of commercial NS and a high pH (pH ≈ 8). The treatment achieved a total coliform removal rate of 100%. Before the LCPm treatment system development, several lime-based reagents were tested under different reaction pH and using mechanical agitation, to access their organic matter removal efficiency, as chemical oxygen demand (COD). The best COD removal results obtained were: commercial Ca(OH) 2 (pH 11.5-89%), reagent grade Ca(OH) 2 (pH 11.5-79%) and CaO (pH 12.0-64%).
Journal of Environmental Sciences, 2019
Increasing concerns have been raised on endocrine disrupting chemicals like the sex hormone 17a-e... more Increasing concerns have been raised on endocrine disrupting chemicals like the sex hormone 17a-ethinylestradiol (EE2), the more since traditional wastewater (WW) treatments appear to be ineffective for their removal. The efficacy of the relatively novel disinfectant peracetic acid (PAA) in EE2 removal was evaluated, as well as its potential effects on WW quality parameters. The treatments tested for EE2 removal were also evaluated in terms of toxicity, through the determination of biochemical responses (antioxidant enzymes, lipid peroxidation and vitellogenin induction) using zebrafish (Danio rerio) as a biological model. PAA contact times less than 20 min appeared insufficient regardless of the PAA dose tested, but a 100% EE2 removal was attained at a PAA concentration of 15 mg/L with a contact time of 20 min. Total suspended solids, chemical oxygen demand and pH in PAA treatments remained well within levels set in European legislation for WW discharge. EE2 induced significant increased vitellogenin (VTG) levels in both female and male fish, indicating increased estrogenic activity, especially in males suggesting an endocrine disruption effect. With the addition of PAA (15 mg/L), however, VTG levels in both sexes returned to control values. Although this PAA treatment showed increased levels of the antioxidant enzyme catalase, the lipid peroxidation levels were similar or even lower than in controls. Overall the results suggest that the use of PAA appears a promising way forward as a less toxic alternative to chlorine disinfection with high efficiency in the removal of EDC like EE2.
Biofilms in RBC with Constant Ages and Thicknesses
Journal of Environmental Engineering, 2019
AbstractWith the exception of some strict kinetic formalism, biofilm thickness constitutes a basi... more AbstractWith the exception of some strict kinetic formalism, biofilm thickness constitutes a basic parameter for analyzing the mechanisms of mass transfer as a result of microbiological growth. A r...
Environmental monitoring and assessment, Jan 2, 2018
The presence of micropollutants that include endocrine-disrupting compounds (EDC) in aquatic envi... more The presence of micropollutants that include endocrine-disrupting compounds (EDC) in aquatic environments is currently one of the most relevant aspects of water quality due to their adverse effects on aquatic organisms and human health. From the several categories of EDC, 17β-estradiol (E2) is a natural hormone, which is prevalent in vertebrates, associated with the female reproductive system and maintenance of the sexual characters. 17α-Ethinylestradiol (EE2) is a synthetic hormone produced from the natural hormone E2 and is an essential component of oral contraceptives. These compounds are susceptible to bioconcentration and have high potential to bioaccumulation. Wastewater treatment plants are the main point source of E2 and EE2 into aquatic environments, but conventional wastewater treatment systems are not specifically designed for steroid removal. To overcome this problem, biological tertiary treatment may be a solution for the removal of emergent pollutants such as E2 and EE...
A Preliminary Assessment of the Present Status of Portuguese Landfills
ABSTRACT In this work we present a preliminary assessment on some landfills from Portugal through... more ABSTRACT In this work we present a preliminary assessment on some landfills from Portugal through following the content in the upflown and dowflown leachate of four target analytes: camphor, octylphenol, diethylphthalate and tributylphosphate. In addition we have tried to simplify the sample treatment using ultrasonic energy in the solid-liquid extraction from the extracting (C 18) column. We have found camphor and octylphenol in the leachates studied whilst diethylphthalate and tributylphosphate were below our detection limits. The use of ultrasonic energy was found inadequate because artifacts were formed that interfere in the subsequent analysis. Some of the landfill leachate treatment plants surveyed are able to diminish the target compounds at the effluent. On the overall our results suggest that it is necessary to undergo a detailed survey in Portugal regarding the performance of landfills plant treatments and its impact in the environment or the nearby zones.
Environmental Monitoring and Assessment, 2013
Biofilms are present in several areas and are studied in microbiology, medical sciences, biology ... more Biofilms are present in several areas and are studied in microbiology, medical sciences, biology and, of course, sanitary engineering. Biofilms are used for the treatment of municipal wastewater, and their application was even before the invention of the activated sludge process. The main objective of this work was to develop a simple, fast and low-cost technique to evaluate the nature of the first decay in the concentration of an organic compound in the presence of a solid material. Though simple, the technique developed has allowed the clarification of whether the initial concentration decay is due to adsorption to the support material or a result of biodegradation. The results show that, with two different support materials, adsorption does not take place, and the biodegradation processes are responsible for the first decay in the organic concentration. The technique used offers a fast and low-cost way of studying the existence of adsorption. Two feed concentration solutions and two different support materials were used.
Environmental Monitoring and Assessment, 2006
Anthropogenic compounds that are able to disrupt the endocrine system of wildlife species are a m... more Anthropogenic compounds that are able to disrupt the endocrine system of wildlife species are a major cause for concern and have led to a demand for new screening methods. The identification and quantification of endocrine disruptor compounds at wastewater treatment plant is of major interest to assess the endocrine activity of wastewater treatment plant discharges into the environment. This study consists of a preliminary survey of concentrations of previously selected endocrine disruptor compounds, undertaken to establish environmental concentrations and to support a biological program assay exposing freshwater fish to them. Selected endocrine disrupting chemicals (APEs, bisphenol A and 17 β-estradiol) were measured in samples from a wastewater treatment plant located in Lisbon (Portugal), using recent commercial enzyme-linked immunosorbent assay kits and also LC-MS/MS. The results show that the wastewater treatment plant treatment process is efficient on the removal of target endocrine disruptor compounds. However, environmentally significant concentrations are still present in the treated effluent. The results also show that enzyme-linked immunosorbent assay kit is suitable for routine analysis of the selected compounds. The results are also useful since the wastewater treatment plant is located in a Mediterranean region, which results in an effluent with its own characteristics.
Journal of Environmental Sciences, 2010
Two media bed (gravel and Filtralite NR) were tested in a mesocosm to evaluate the removal of org... more Two media bed (gravel and Filtralite NR) were tested in a mesocosm to evaluate the removal of organic matter (as chemical oxygen demand (COD)), ammonia (NH 4-N), nitrite, nitrate and solid matter (as total suspended solids (TSS)) for a synthetic wastewater (acetate-based) and a domestic wastewater. The use of Filtralite allowed average removal rates (6-16.8 g COD/(m 2 •day), 0.8-1.1 g NH 4-N/(m 2 •day) and 3.1 g TSS/(m 2 •day)) and removal efficiencies (65%-93%, 57%-85% and 78% for COD, NH 4-N and TSS, respectively), higher than that observed in the experiments with gravel. The applied loads of COD, ammonia, nitrate and TSS seem to influence the respective removal rates but only for the treatment of domestic wastewater with higher correlation coefficients for Filtralite. Regardless the type of media bed and the type of wastewater, nitrate was completely removed for nitrogen loading rates up to 1.3 g NO 3-N/(m 2 •day). There was no evidence of the influence of nitrate loads on the removal of organic matter.
Bioresource Technology, 2009
I In nf fl lu ue en nc ce e o of f b be ed d m me ed di ia a c ch ha ar ra ac ct te er ri is st t... more I In nf fl lu ue en nc ce e o of f b be ed d m me ed di ia a c ch ha ar ra ac ct te er ri is st ti ic cs s o on n a am mm mo on ni ia a a an nd d n ni it tr ra at te e r re em mo ov va al l i in n s sh ha al ll lo ow w h ho or ri iz zo on nt ta al l s su ub bs su ur rf fa ac ce e f fl lo ow w c co on ns st tr ru uc ct te ed d w we et tl la an nd ds s
Impact of Mass Loading Rate and Vegetation on the Performance of Horizontal Subsurface Flow Constructed Wetlands
ABSTRACT Constructed wetlands (CW) are sustainable wastewater treatment processes, especially for... more ABSTRACT Constructed wetlands (CW) are sustainable wastewater treatment processes, especially for small communities. In order to evaluate the effect of mass loading rates and the presence of plants on the removal of organic matter and ammonia in horizontal subsurface flow CW, two set of experiments were carried out at different organic and ammonia loading rates in two mesocosms, one without plants, other colonized with Phragmites australis. Regardless the mass loading rates, the COD removal was significantly greater in the bed containing plants (70.3% and 75.6%, respectively, for the lower and the higher organic loads) than in the bed without plants (38.5% and 44.4%, respectively). The removal of NH4-N was also significantly higher in the planted bed (59.3% and 47.8%, respectively, for the lower and the higher nitrogen loads) than in bed without plants (34% and 33%, respectively). The removal of organic matter and ammonia was higher in the first section of the bed (first 33 cm) in the unplanted system (> 75%) and was more distributed through the bed in the planted system, which seems to have been associated with the growth of roots and rhizomes that support the biofilm as well as the release of oxygen in the root zone.
Journal of Environmental Sciences, 2010
The estrogenic potency of a wastewater treatment plant (WWTP) was evaluated using chemical and bi... more The estrogenic potency of a wastewater treatment plant (WWTP) was evaluated using chemical and biological analyses, which showed that after the station treatment processes some of the selected endocrine disruptor compounds (EDCs) were still present in the treated effluent (e.g., bisphenol A, alkylphenols, estrone). Thus, the most common endocrine EDCs were identified and quantified and the overall estrogenicity of the treated effluent assessed by integrating the results. Male goldfish (Carassius auratus) were used as biological indicators in a 28-day experiment. Vitellogenin (Vtg), gonadosomatic and hepatosomatic indices, steroids (17β-estradiol and 11-ketotestosterone) and histopathology were biomarkers used in fish to evaluate WWTP treated effluent estrogenicity, in combination with instrumental analyses. The results showed a significant increase (P < 0.01) in plasma and liver Vtg, which were significantly correlated (r = 0.66; P < 0.01). The gonadosmatic index was significantly (P < 0.01) reduced in exposed fish. The steroid analyses revealed significant elevations in 17β-estradiol and depressed 11-ketotestosterone concentrations. The histological examinations show changes in exposed fish gonads, such as regressed testes and in some cases (43% to 75%) the development of ovo-testis in fish exposed to 50% and 100% treated effluent.
Effects of landfill age, climate, and size on leachate from urban waste landfills in Portugal: A statistics and machine learning analysis
Waste Management
Evaluation of Circular Performance Models in Wastewater Treatment Plants: Portugal Case-Study
Lecture notes in civil engineering, 2024
In an increasing water scarcity and climate-vulnerable global context, treated wastewater represe... more In an increasing water scarcity and climate-vulnerable global context, treated wastewater represents a vital alternative water source, thereby enhancing resource sustainability. Despite its potential, only roughly 2.5 % of the treated wastewater is reused in the European Union, with Portugal's reuse rate being only 1.2 % in 2022. Considering this framework, this study evaluates the feasibility of increasing wastewater reuse in Portugal by focusing on the Tagus River and Ribeiras do Oeste Basins. The regional assessment identified eight key wastewater treatment plants (WWTP) with significant potential for irrigation reuse in the agriculture and tourism sectors. Analysing costs, quality requirements, and technological options, this study considered five treatment lines, incorporating filtration and disinfection methods. The findings indicate that reclaimed water costs may range from 0.02€/m3 to 0.83€/m3, being competitive with other water sources and significantly lower than desalination processes (up to 1.66€/m3). Distribution investments and energy consumption are primary cost drivers, suggesting a relocation of WWTP closer to end-users as a cost-saving strategy. The proposed reuse projects could quadruple regional reuse rates and double the national rate, mitigating water needs for over 2000 ha of agricultural land and golf courses. This study underscores the importance of treated wastewater reuse in addressing water scarcity, advocating for WWTP decentralisation, strategic investments and policy interventions to achieve cost-effective goals. The methodologies and insights presented offer valuable guidance for other regions facing similar challenges, promoting a paradigm shift towards circular water resource management.
Energy Procedia, Oct 1, 2017
District heating networks are commonly addressed in the literature as one of the most effective s... more District heating networks are commonly addressed in the literature as one of the most effective solutions for decreasing the greenhouse gas emissions from the building sector. These systems require high investments which are returned through the heat sales. Due to the changed climate conditions and building renovation policies, heat demand in the future could decrease, prolonging the investment return period. The main scope of this paper is to assess the feasibility of using the heat demand-outdoor temperature function for heat demand forecast. The district of Alvalade, located in Lisbon (Portugal), was used as a case study. The district is consisted of 665 buildings that vary in both construction period and typology. Three weather scenarios (low, medium, high) and three district renovation scenarios were developed (shallow, intermediate, deep). To estimate the error, obtained heat demand values were compared with results from a dynamic heat demand model, previously developed and validated by the authors. The results showed that when only weather change is considered, the margin of error could be acceptable for some applications (the error in annual demand was lower than 20% for all weather scenarios considered). However, after introducing renovation scenarios, the error value increased up to 59.5% (depending on the weather and renovation scenarios combination considered). The value of slope coefficient increased on average within the range of 3.8% up to 8% per decade, that corresponds to the decrease in the number of heating hours of 22-139h during the heating season (depending on the combination of weather and renovation scenarios considered). On the other hand, function intercept increased for 7.8-12.7% per decade (depending on the coupled scenarios). The values suggested could be used to modify the function parameters for the scenarios considered, and improve the accuracy of heat demand estimations.
Water, 2016
To improve nutrient removal, a full-scale hybrid constructed wetland (CW) consisting of pre-treat... more To improve nutrient removal, a full-scale hybrid constructed wetland (CW) consisting of pre-treatment units, vertical-baffled flow wetlands (VBFWs), and horizontal subsurface flow wetlands (HSFWs) was installed in August 2014 to treat sewage wastewater. Artificial aeration (AA) was applied continuously in the VBFW stage to improve the aerobic condition in the hybrid CW. Water samples were collected and analyzed twice a month between the period of August 2015 and July 2016. The results suggest that this new hybrid CW can achieve a satisfactory reduction of chemical oxygen demand (COD), ammonium nitrogen (NH 4 +-N), total nitrogen (TN), and total phosphorus (TP) with average removal rates of 85% ± 10% (35% ± 19 g/m 2 per day), 76% ± 18% (7% ± 2 g/m 2 per day), 65% ± 13% (8% ± 2 g/m 2 per day), and 65% ± 21% (1 g/m 2 per day), respectively. AA significantly improved the aerobic condition throughout the experimental period, and the positive influence of AA on nitrogen removal was found to be higher during summer that during winter. A significant positive correlation between water temperature and nutrient removal (p < 0.01) was observed in the system. Overall, this study demonstrates the application of AA in a full-scale hybrid CW with satisfactory nutrient removal rates. The hybrid CW system with artificial aeration can serve as a reference for future applications areas where land availability is limited.
Journal of Water and Climate Change, 2021
The presence of salt water from the Tagus Estuary has been identified in the influent at Barreiro... more The presence of salt water from the Tagus Estuary has been identified in the influent at Barreiro/Moita Wastewater Treatment Plant (WWTP), Portugal. The intrusion occurs throughout damaged sections and direct vectors in the wastewater collection system, during high tide levels, changing the wastewater characteristics and impacting the WWTP process. This study designed models to quantify this problem, enabling more effective countermeasures within the right timing. The proposed models estimate the average volume of salt water and sulfate () load for each high tide period. The laboratory results show strong correlations between the influent electrical conductivity (EC) and percentage of salt water in WWTP inflow (0.9909), and between EC and concentration in WWTP influent (0.9797). The forecast models also show good correlation between the high tide levels with volume of salt water (0.9145) and load (0.9162) entering the system. Considering the total monthly inflow, the highest percent...
Water Practice and Technology, 2020
Salt water from the Tagus Estuary has been identified in the influent at Barreiro/Moita Wastewate... more Salt water from the Tagus Estuary has been identified in the influent at Barreiro/Moita Wastewater Treatment Plant (WWTP), Portugal. The saltwater intrusion occurs during high tide levels in the estuary throughout damaged sections and direct vectors in the sewer network, changing the wastewater characteristics impacting the WWTP processes. This work has designed a methodology to assess from which tide level in the Tagus Estuary saltwater intrusion occurs in the sewer network by measuring WWTP influent's electric conductivity (EC). The methodology identifies saltwater intrusion for tide levels higher than 3.10 m, increasing significantly for tide levels higher than 4.00 m. During this study, 86% of the days registered at least one high tide level higher than 3.10 m, and 8% higher than 4.00 m, demonstrating a considerable occurrence of saltwater intrusion in the system with a tendency to increase due to the mean sea level rise registered in the Tagus Estuary. To prevent it, it is ...
Microplastics from Wastewater Treatment Plants—Preliminary Data
Springer Water, 2017
Wastewater treatment plants (WWTIP) are a potential source of microplastics [1,2]. Several types ... more Wastewater treatment plants (WWTIP) are a potential source of microplastics [1,2]. Several types of microplastics, namely microbeads, fibres and fragments, were analysed in two WWTP effluent serving different Portuguese communities. A bigger station treating mixed domestic and industrial wastewater averaging 18000 m day and a smaller station with treating mostly domestic wastewater averaging 7250 m day. A total of 6065 microplastics were observed in 5,5 litres of wastewater sampled. 90% of the microplastics analysed were fragments and 88% were collected from treated effluent (1687 items in average per litre). Fibres presented a higher percentage in the affluent (88%), comparing to treated effluent (12%). Regarding sizes, microplastics with less than 0, 5 mm were the most representative in both WWTP. Fibres with 1 to 2 mm were more common. This study intends to contribute with a standardized methodology to analyse microplastics in wastewater, from sampling to identification, measuring and handling processes in the laboratory.
Journal of Ecological Engineering, 2020
An urban wastewater treatment system was developed in Portugal for posterior in situ feasibility ... more An urban wastewater treatment system was developed in Portugal for posterior in situ feasibility testing at the Bulgarian Antarctic Base, using its domestic wastewater. The aim of this system was to develop a low cost, integrated approach for wastewater treatment and production of nutrient solutions (NS) for hydroponic cultivation of lettuce (Lactuca sativa var. crispa) in Antarctic stations, or any other place where the lack of resources and logistical hardships make the wastewater treatment and reuse impractical. The wastewater treatment system consisted in manual agitation lime chemical precipitation (LCPm) and effluent natural neutralization (NN) by atmospheric CO 2 carbonation reactions (with and without air injection). The resulting effluent/NS had macronutrient values (nitrogen and phosphorous) for the hydroponic cultivation of lettuce below the values of commercial NS and a high pH (pH ≈ 8). The treatment achieved a total coliform removal rate of 100%. Before the LCPm treatment system development, several lime-based reagents were tested under different reaction pH and using mechanical agitation, to access their organic matter removal efficiency, as chemical oxygen demand (COD). The best COD removal results obtained were: commercial Ca(OH) 2 (pH 11.5-89%), reagent grade Ca(OH) 2 (pH 11.5-79%) and CaO (pH 12.0-64%).
Journal of Environmental Sciences, 2019
Increasing concerns have been raised on endocrine disrupting chemicals like the sex hormone 17a-e... more Increasing concerns have been raised on endocrine disrupting chemicals like the sex hormone 17a-ethinylestradiol (EE2), the more since traditional wastewater (WW) treatments appear to be ineffective for their removal. The efficacy of the relatively novel disinfectant peracetic acid (PAA) in EE2 removal was evaluated, as well as its potential effects on WW quality parameters. The treatments tested for EE2 removal were also evaluated in terms of toxicity, through the determination of biochemical responses (antioxidant enzymes, lipid peroxidation and vitellogenin induction) using zebrafish (Danio rerio) as a biological model. PAA contact times less than 20 min appeared insufficient regardless of the PAA dose tested, but a 100% EE2 removal was attained at a PAA concentration of 15 mg/L with a contact time of 20 min. Total suspended solids, chemical oxygen demand and pH in PAA treatments remained well within levels set in European legislation for WW discharge. EE2 induced significant increased vitellogenin (VTG) levels in both female and male fish, indicating increased estrogenic activity, especially in males suggesting an endocrine disruption effect. With the addition of PAA (15 mg/L), however, VTG levels in both sexes returned to control values. Although this PAA treatment showed increased levels of the antioxidant enzyme catalase, the lipid peroxidation levels were similar or even lower than in controls. Overall the results suggest that the use of PAA appears a promising way forward as a less toxic alternative to chlorine disinfection with high efficiency in the removal of EDC like EE2.
Biofilms in RBC with Constant Ages and Thicknesses
Journal of Environmental Engineering, 2019
AbstractWith the exception of some strict kinetic formalism, biofilm thickness constitutes a basi... more AbstractWith the exception of some strict kinetic formalism, biofilm thickness constitutes a basic parameter for analyzing the mechanisms of mass transfer as a result of microbiological growth. A r...
Environmental monitoring and assessment, Jan 2, 2018
The presence of micropollutants that include endocrine-disrupting compounds (EDC) in aquatic envi... more The presence of micropollutants that include endocrine-disrupting compounds (EDC) in aquatic environments is currently one of the most relevant aspects of water quality due to their adverse effects on aquatic organisms and human health. From the several categories of EDC, 17β-estradiol (E2) is a natural hormone, which is prevalent in vertebrates, associated with the female reproductive system and maintenance of the sexual characters. 17α-Ethinylestradiol (EE2) is a synthetic hormone produced from the natural hormone E2 and is an essential component of oral contraceptives. These compounds are susceptible to bioconcentration and have high potential to bioaccumulation. Wastewater treatment plants are the main point source of E2 and EE2 into aquatic environments, but conventional wastewater treatment systems are not specifically designed for steroid removal. To overcome this problem, biological tertiary treatment may be a solution for the removal of emergent pollutants such as E2 and EE...
A Preliminary Assessment of the Present Status of Portuguese Landfills
ABSTRACT In this work we present a preliminary assessment on some landfills from Portugal through... more ABSTRACT In this work we present a preliminary assessment on some landfills from Portugal through following the content in the upflown and dowflown leachate of four target analytes: camphor, octylphenol, diethylphthalate and tributylphosphate. In addition we have tried to simplify the sample treatment using ultrasonic energy in the solid-liquid extraction from the extracting (C 18) column. We have found camphor and octylphenol in the leachates studied whilst diethylphthalate and tributylphosphate were below our detection limits. The use of ultrasonic energy was found inadequate because artifacts were formed that interfere in the subsequent analysis. Some of the landfill leachate treatment plants surveyed are able to diminish the target compounds at the effluent. On the overall our results suggest that it is necessary to undergo a detailed survey in Portugal regarding the performance of landfills plant treatments and its impact in the environment or the nearby zones.
Environmental Monitoring and Assessment, 2013
Biofilms are present in several areas and are studied in microbiology, medical sciences, biology ... more Biofilms are present in several areas and are studied in microbiology, medical sciences, biology and, of course, sanitary engineering. Biofilms are used for the treatment of municipal wastewater, and their application was even before the invention of the activated sludge process. The main objective of this work was to develop a simple, fast and low-cost technique to evaluate the nature of the first decay in the concentration of an organic compound in the presence of a solid material. Though simple, the technique developed has allowed the clarification of whether the initial concentration decay is due to adsorption to the support material or a result of biodegradation. The results show that, with two different support materials, adsorption does not take place, and the biodegradation processes are responsible for the first decay in the organic concentration. The technique used offers a fast and low-cost way of studying the existence of adsorption. Two feed concentration solutions and two different support materials were used.
Environmental Monitoring and Assessment, 2006
Anthropogenic compounds that are able to disrupt the endocrine system of wildlife species are a m... more Anthropogenic compounds that are able to disrupt the endocrine system of wildlife species are a major cause for concern and have led to a demand for new screening methods. The identification and quantification of endocrine disruptor compounds at wastewater treatment plant is of major interest to assess the endocrine activity of wastewater treatment plant discharges into the environment. This study consists of a preliminary survey of concentrations of previously selected endocrine disruptor compounds, undertaken to establish environmental concentrations and to support a biological program assay exposing freshwater fish to them. Selected endocrine disrupting chemicals (APEs, bisphenol A and 17 β-estradiol) were measured in samples from a wastewater treatment plant located in Lisbon (Portugal), using recent commercial enzyme-linked immunosorbent assay kits and also LC-MS/MS. The results show that the wastewater treatment plant treatment process is efficient on the removal of target endocrine disruptor compounds. However, environmentally significant concentrations are still present in the treated effluent. The results also show that enzyme-linked immunosorbent assay kit is suitable for routine analysis of the selected compounds. The results are also useful since the wastewater treatment plant is located in a Mediterranean region, which results in an effluent with its own characteristics.
Journal of Environmental Sciences, 2010
Two media bed (gravel and Filtralite NR) were tested in a mesocosm to evaluate the removal of org... more Two media bed (gravel and Filtralite NR) were tested in a mesocosm to evaluate the removal of organic matter (as chemical oxygen demand (COD)), ammonia (NH 4-N), nitrite, nitrate and solid matter (as total suspended solids (TSS)) for a synthetic wastewater (acetate-based) and a domestic wastewater. The use of Filtralite allowed average removal rates (6-16.8 g COD/(m 2 •day), 0.8-1.1 g NH 4-N/(m 2 •day) and 3.1 g TSS/(m 2 •day)) and removal efficiencies (65%-93%, 57%-85% and 78% for COD, NH 4-N and TSS, respectively), higher than that observed in the experiments with gravel. The applied loads of COD, ammonia, nitrate and TSS seem to influence the respective removal rates but only for the treatment of domestic wastewater with higher correlation coefficients for Filtralite. Regardless the type of media bed and the type of wastewater, nitrate was completely removed for nitrogen loading rates up to 1.3 g NO 3-N/(m 2 •day). There was no evidence of the influence of nitrate loads on the removal of organic matter.
Bioresource Technology, 2009
I In nf fl lu ue en nc ce e o of f b be ed d m me ed di ia a c ch ha ar ra ac ct te er ri is st t... more I In nf fl lu ue en nc ce e o of f b be ed d m me ed di ia a c ch ha ar ra ac ct te er ri is st ti ic cs s o on n a am mm mo on ni ia a a an nd d n ni it tr ra at te e r re em mo ov va al l i in n s sh ha al ll lo ow w h ho or ri iz zo on nt ta al l s su ub bs su ur rf fa ac ce e f fl lo ow w c co on ns st tr ru uc ct te ed d w we et tl la an nd ds s
Impact of Mass Loading Rate and Vegetation on the Performance of Horizontal Subsurface Flow Constructed Wetlands
ABSTRACT Constructed wetlands (CW) are sustainable wastewater treatment processes, especially for... more ABSTRACT Constructed wetlands (CW) are sustainable wastewater treatment processes, especially for small communities. In order to evaluate the effect of mass loading rates and the presence of plants on the removal of organic matter and ammonia in horizontal subsurface flow CW, two set of experiments were carried out at different organic and ammonia loading rates in two mesocosms, one without plants, other colonized with Phragmites australis. Regardless the mass loading rates, the COD removal was significantly greater in the bed containing plants (70.3% and 75.6%, respectively, for the lower and the higher organic loads) than in the bed without plants (38.5% and 44.4%, respectively). The removal of NH4-N was also significantly higher in the planted bed (59.3% and 47.8%, respectively, for the lower and the higher nitrogen loads) than in bed without plants (34% and 33%, respectively). The removal of organic matter and ammonia was higher in the first section of the bed (first 33 cm) in the unplanted system (> 75%) and was more distributed through the bed in the planted system, which seems to have been associated with the growth of roots and rhizomes that support the biofilm as well as the release of oxygen in the root zone.
Journal of Environmental Sciences, 2010
The estrogenic potency of a wastewater treatment plant (WWTP) was evaluated using chemical and bi... more The estrogenic potency of a wastewater treatment plant (WWTP) was evaluated using chemical and biological analyses, which showed that after the station treatment processes some of the selected endocrine disruptor compounds (EDCs) were still present in the treated effluent (e.g., bisphenol A, alkylphenols, estrone). Thus, the most common endocrine EDCs were identified and quantified and the overall estrogenicity of the treated effluent assessed by integrating the results. Male goldfish (Carassius auratus) were used as biological indicators in a 28-day experiment. Vitellogenin (Vtg), gonadosomatic and hepatosomatic indices, steroids (17β-estradiol and 11-ketotestosterone) and histopathology were biomarkers used in fish to evaluate WWTP treated effluent estrogenicity, in combination with instrumental analyses. The results showed a significant increase (P < 0.01) in plasma and liver Vtg, which were significantly correlated (r = 0.66; P < 0.01). The gonadosmatic index was significantly (P < 0.01) reduced in exposed fish. The steroid analyses revealed significant elevations in 17β-estradiol and depressed 11-ketotestosterone concentrations. The histological examinations show changes in exposed fish gonads, such as regressed testes and in some cases (43% to 75%) the development of ovo-testis in fish exposed to 50% and 100% treated effluent.