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Currently, in sub-Saharan African countries, 65 to 100% of the urban population is served by on-site sanitation systems, typically pit latrines and septic tanks. Faecal sludge dewatering in drying beds is one of the most commonly adopted low-cost treatment technologies in developing countries due to favourable climate conditions in terms of temperature and radiation and because their operation and maintenance are simple. Nevertheless, research in tropical dry zones regarding these processes is scarce. In this paper, a mathematical model for faecal sludge dewatering in sludge drying beds (SDBs) focusing on gravity drainage and evaporation processes is presented and discussed. Experimental campaigns were carried out at a pilot site in Tete, Mozambique, to determine the model parameters. The results suggest that the model can be used to estimate, in similar situations, the dewatering process of different types of faecal sludge. The present research might be considered as a contribution to the design and operation of SDBs, supporting sludge management and allowing the estimation of drying times and optimal loading cycles, namely, the sludge thickness and final moisture content.
Osvaldo Moiambo; Raúl Mutevuie; Filipa Ferreira; José Matos. Modelling Faecal Sludge Dewatering Processes in Drying Beds Based on the Results from Tete, Mozambique. Sustainability 2021, 13, 8981 .
AMA StyleOsvaldo Moiambo, Raúl Mutevuie, Filipa Ferreira, José Matos. Modelling Faecal Sludge Dewatering Processes in Drying Beds Based on the Results from Tete, Mozambique. Sustainability. 2021; 13 (16):8981.
Chicago/Turabian StyleOsvaldo Moiambo; Raúl Mutevuie; Filipa Ferreira; José Matos. 2021. "Modelling Faecal Sludge Dewatering Processes in Drying Beds Based on the Results from Tete, Mozambique." Sustainability 13, no. 16: 8981.
In this paper, an expedited multi-criteria decision analysis framework, capable of tackling several dimensions for the choice of sanitation services, at an early planning stage is presented. The approach combines geographic information systems aided analysis for onsite solutions, with a multi-criteria decision analysis tool capable of suggesting and ranking several viable offsite treatment alternatives, according to the desired criteria. The framework was applied to four coastal cities in Northern Angola, one of the sub-Saharan countries of the west coast of Africa, thus obtaining an indication for city-wide solutions, as an aid to achieve the goal of ensuring full sanitation coverage in those four locations. It included possible onsite collection and storage interfaces, namely Ventilated Improved Pit latrines, fossa alterna, septic tanks or conventional sewer systems. The study also contributed to an informed decision regarding optimal offsite treatment facility type, namely based on dedicated or combined wastewater and faecal sludge treatment (co-treatment), as well as different options for locations and sanitation technologies. Alternatives were compared and ranked according to ten main criteria concerning social, economic, technological and environmental aspects. This work helped demonstrate the usefulness of decision-aiding tools in the multi-stakeholder and complex context of sanitation in a developing country.
Rita Matos; Filipa Ferreira; Liliana Alves; Elsa Ramos; Lucrécio Costa; José Matos. Multi-Criteria Framework for Selection of City-Wide Sanitation Solutions in Coastal Towns in Northern Angola. Sustainability 2021, 13, 5627 .
AMA StyleRita Matos, Filipa Ferreira, Liliana Alves, Elsa Ramos, Lucrécio Costa, José Matos. Multi-Criteria Framework for Selection of City-Wide Sanitation Solutions in Coastal Towns in Northern Angola. Sustainability. 2021; 13 (10):5627.
Chicago/Turabian StyleRita Matos; Filipa Ferreira; Liliana Alves; Elsa Ramos; Lucrécio Costa; José Matos. 2021. "Multi-Criteria Framework for Selection of City-Wide Sanitation Solutions in Coastal Towns in Northern Angola." Sustainability 13, no. 10: 5627.
The work presented herein was carried out to assess the effect of intermittent pumping events in sewer headspace pressure differentials, as well as their relationship with hydrogen sulfide gas concentration. A full scale gravity sewer in Portugal, located downstream of several pumping stations, was used as the guiding case study. Under normal system operation, pressure difference between the outside atmosphere and the sewer headspace seemed to influence the in and out-gassing of gas pollutants emitted through the venting stack. Wastewater pumping cycles generated maximum pressure differentials of roughly 100 Pa, which in turn originated maximum air velocities of 1.76 m s−1 exiting the venting stack. Each pumping event was followed by a pressure drop of about 50 Pa, quickly attaining null concentrations of H2S at the venting stack. A statistically significant relationship between pressure differentials and air exit velocity was observed, which allowed obtaining an empirical equation for expedite prediction of airflows emitted to the outside atmosphere (R2 = 0.77). Conversely, the same effect was not observed along the length of the sewer pipe, unlike the findings of other studies. The effect of a full flowing pipe at the downstream end of the gravity trunk sewer was also noticeable in downstream sewer pressurization and gas build-up. It was concluded that the magnitude of the gas pollutant emissions may heavily depend on the impacts of hydraulic flows and pumping characteristics in headspace pressure differences, denoting the need for better approaches when designing and installing venting stacks.
Rita Ventura Matos; Filipa Ferreira; José Saldanha Matos. Influence of Intermittence and Pressure Differentials in Hydrogen Sulfide Concentration in a Gravity Sewer. Water 2019, 11, 1780 .
AMA StyleRita Ventura Matos, Filipa Ferreira, José Saldanha Matos. Influence of Intermittence and Pressure Differentials in Hydrogen Sulfide Concentration in a Gravity Sewer. Water. 2019; 11 (9):1780.
Chicago/Turabian StyleRita Ventura Matos; Filipa Ferreira; José Saldanha Matos. 2019. "Influence of Intermittence and Pressure Differentials in Hydrogen Sulfide Concentration in a Gravity Sewer." Water 11, no. 9: 1780.
Gas pollutants emitted during wastewater transport contribute to atmospheric pollution, aggravated risks for utility workers, infrastructure corrosion, and odour nuisance. Field studies have shown that is difficult to effectively obtain reliable correlations between in-sewer air movement and gas pollutant concentrations. This study aimed at investigating the influence of different ventilation and operating conditions in H2S and CH4 horizontal and vertical movement in a section of a gravity sewer, downstream of a pumping station. Relevant liquid and gas phase quality parameters were monitored, and significant H2S concentrations were measured (with lower contents of CH4). Results evidenced that headspace temperature and ventilation played a key effect when analysing H2S and CH4 dynamics. Setups with a similar content of sulfide and chemical oxygen demand resulted in different H2S and CH4 headspace concentrations. It was also observed that an increase in ventilation resulted in a decrease of average headspace relative humidity of over 70%, with clear implications in corrosion potential estimates. Another interesting observation was that the wastewater drag induced by intermittent pumping, in absence of ingassing, originated pressure differences of up to 0.2 Pa m−1 between studied manholes. This differential originated a wave pattern of gas moving upstream and downstream, thus resulting in several gas peaks per pumping event, at the same sections. In addition, in confined setups, full mixing was not observed along the manholes.
Rita Ventura Matos; Filipa Ferreira; Carla Gil; José Saldanha Matos. Understanding the effect of ventilation, intermittent pumping and seasonality in hydrogen sulfide and methane concentrations in a coastal sewerage system. Environmental Science and Pollution Research 2018, 26, 3404 -3414.
AMA StyleRita Ventura Matos, Filipa Ferreira, Carla Gil, José Saldanha Matos. Understanding the effect of ventilation, intermittent pumping and seasonality in hydrogen sulfide and methane concentrations in a coastal sewerage system. Environmental Science and Pollution Research. 2018; 26 (4):3404-3414.
Chicago/Turabian StyleRita Ventura Matos; Filipa Ferreira; Carla Gil; José Saldanha Matos. 2018. "Understanding the effect of ventilation, intermittent pumping and seasonality in hydrogen sulfide and methane concentrations in a coastal sewerage system." Environmental Science and Pollution Research 26, no. 4: 3404-3414.
Production and build-up of sulfide in wastewater systems, especially downstream of rising mains, may lead to severe odour nuisance, toxic environments and high risk of corrosion. Due to increased population migration towards cities and lower area availability for treatment facilities, rising mains for the conveyance of wastewater sludge are becoming more frequent, and research on sulfide build-up in such cases is needed. In this paper the findings of the work carried out in a full scale wastewater sludge rising main, operated during different seasons and under distinct conditions are presented (comprising both the start-up and normal operation stages of the facility). Results showed a sulfide build-up rate of 3.24 g S−2 m−2 d−1 in the summer and of 2.30 g S−2 m−2 d−1 during the winter. The ratio of sulfate reduction to sulfide production (SO4−2/S−2) was of roughly 3 to 1, as expected. Furthermore, obtained results allowed adjusting a second order polynomial empirical equation for the forecasting of sulfide build-up within the sludge rising main. The obtained equation for sludge significantly differs from existing equations obtained for wastewater. Moreover, this work also allowed obtaining new insight into the positive influence of biofilm and hydraulic retention time in the biological sulfide generation, as well as into its variation along the length of the rising main.
Rita Ventura Matos; Natércia Matias; Filipa Ferreira; João Santos Silva; José Saldanha Matos. Assessment of sulfide production in a full scale wastewater sludge rising main. Journal of Environmental Management 2018, 209, 505 -514.
AMA StyleRita Ventura Matos, Natércia Matias, Filipa Ferreira, João Santos Silva, José Saldanha Matos. Assessment of sulfide production in a full scale wastewater sludge rising main. Journal of Environmental Management. 2018; 209 ():505-514.
Chicago/Turabian StyleRita Ventura Matos; Natércia Matias; Filipa Ferreira; João Santos Silva; José Saldanha Matos. 2018. "Assessment of sulfide production in a full scale wastewater sludge rising main." Journal of Environmental Management 209, no. : 505-514.
Mass transfer of a range of volatile substances was studied under highly turbulent conditions. The applied setup mimicked drop structures, where the release of volatile organic carbons likely occurs at a high rate. The experiments covered several substances in a range of resistances from residing entirely in the liquid film to being fully in the gas film. The two-film theory yielded a good prediction of the whole measured range. This allowed the experimental validation of a method where two reference substances are applied, to determine the transfer of any other substance - independently of where its resistance to mass transfer resides. One finding was that the range of dimensionless Henry's constants, where both films contributed by more than 5%, was 0.0027 to 1.05, which is over five times higher than the accepted rule of thumb (0.0005‐0.18). Another finding was that the ratio between the liquid and the gas film mass transfer coefficients of the reference substances was similar for the two drop configurations studied. If this holds true over a wider range of configurations, such a ratio constitutes a valuable shortcut to the current practice of ignoring gas film resistance in the estimation of mass transfer rates.
Natércia Matias; Filipa Ferreira; José Saldanha Matos; Asbjørn Haaning Nielsen; Jes Vollertsen. Liquid-Gas Mass Transfer of Volatile Substances in an Energy Dissipating Structure. Water Environment Research 2018, 90, 269 -277.
AMA StyleNatércia Matias, Filipa Ferreira, José Saldanha Matos, Asbjørn Haaning Nielsen, Jes Vollertsen. Liquid-Gas Mass Transfer of Volatile Substances in an Energy Dissipating Structure. Water Environment Research. 2018; 90 (3):269-277.
Chicago/Turabian StyleNatércia Matias; Filipa Ferreira; José Saldanha Matos; Asbjørn Haaning Nielsen; Jes Vollertsen. 2018. "Liquid-Gas Mass Transfer of Volatile Substances in an Energy Dissipating Structure." Water Environment Research 90, no. 3: 269-277.
For engineering purposes it is especially useful to be able to predict and control sewer corrosion rates and odor impacts as well as to design effective measures aiming to reduce effects related to hydrogen sulfide formation and release. Doing so, it is important to use modeling tools that are capable of assessing variations of dissolved oxygen, dissolved sulfide and hydrogen sulfide gas concentrations for a wide range of environmental scenarios. Two such models were assessed: AEROSEPT, an empirical formulation, and WATS, a conceptual and more complex approach. The models were applied to evaluate the effects of transitions between pressure mains and gravity sewers in the air–liquid mass transfer of hydrogen sulfide at the Ericeira sewer system in Portugal. This network is known to have odor and corrosion problems, especially during summer. Despite the unavoidable uncertainties due to the unsteady flow rate and the quantification of air velocity and turbulence, the simulation results obtained with both models have been shown to adequately predict the overall behavior of the system.
Natércia Matias; Rita Ventura Matos; Filipa Ferreira; Jes Vollertsen; José Saldanha Matos. Release of hydrogen sulfide under intermittent flow conditions – the potential of simulation models. Water Science and Technology 2017, 77, 777 -787.
AMA StyleNatércia Matias, Rita Ventura Matos, Filipa Ferreira, Jes Vollertsen, José Saldanha Matos. Release of hydrogen sulfide under intermittent flow conditions – the potential of simulation models. Water Science and Technology. 2017; 77 (3):777-787.
Chicago/Turabian StyleNatércia Matias; Rita Ventura Matos; Filipa Ferreira; Jes Vollertsen; José Saldanha Matos. 2017. "Release of hydrogen sulfide under intermittent flow conditions – the potential of simulation models." Water Science and Technology 77, no. 3: 777-787.
P. Póvoa; José Matos; Adrian Oehmen. Modelling operational costs of a large water resource recovery facility receiving stormwater contributions. Urban Water Journal 2017, 15, 23 -31.
AMA StyleP. Póvoa, José Matos, Adrian Oehmen. Modelling operational costs of a large water resource recovery facility receiving stormwater contributions. Urban Water Journal. 2017; 15 (1):23-31.
Chicago/Turabian StyleP. Póvoa; José Matos; Adrian Oehmen. 2017. "Modelling operational costs of a large water resource recovery facility receiving stormwater contributions." Urban Water Journal 15, no. 1: 23-31.
Over the last decades, considerable progress has been made in the understanding of the sulfur cycle in sewer systems. In spite of a wealth of experimental and field studies that have addressed the release of hydrogen sulfide from free surface flows in gravity sewers and the corresponding air-water mass transfer, little is known about hydrogen sulfide emission under highly turbulent conditions (e.g., drop structures, hydraulic jumps). In this study, experimental work was carried out to analyze the influence of characteristics of drops on reaeration. Physical models were built, mimicking typical sewer drop structures and allowing different types of drops, drop heights, tailwater depths and flow rates. In total, 125 tests were performed. Based on their results, empirical expressions translating the relationship between the mass transfer of oxygen and physical parameters of drop structures were established. Then, by applying the two-film theory with two-reference substances, the relation to hydrogen sulfide release was defined. The experiments confirmed that the choice of the type of drop structure is critical to determine the uptake/emission rates. By quantifying the air-water mass transfer rates between free-fall and backdrop types of drop, the latter resulted in considerably lower oxygen uptake rates.
Natércia Matias; Asbjèrn Haaning Nielsen; Jes Vollertsen; Filipa Ferreira; José Matos. Erratum: Water Science and Technology 75 (10), 2257–2267: Liquid-gas mass transfer at drop structures, Natércia Matias, Asbjørn Haaning Nielsen, Jes Vollertsen, Filipa Ferreira and José Saldanha Matos, doi: 10.2166/wst.2017.103. Water Science and Technology 2017, 76, 1584 -1594.
AMA StyleNatércia Matias, Asbjèrn Haaning Nielsen, Jes Vollertsen, Filipa Ferreira, José Matos. Erratum: Water Science and Technology 75 (10), 2257–2267: Liquid-gas mass transfer at drop structures, Natércia Matias, Asbjørn Haaning Nielsen, Jes Vollertsen, Filipa Ferreira and José Saldanha Matos, doi: 10.2166/wst.2017.103. Water Science and Technology. 2017; 76 (6):1584-1594.
Chicago/Turabian StyleNatércia Matias; Asbjèrn Haaning Nielsen; Jes Vollertsen; Filipa Ferreira; José Matos. 2017. "Erratum: Water Science and Technology 75 (10), 2257–2267: Liquid-gas mass transfer at drop structures, Natércia Matias, Asbjørn Haaning Nielsen, Jes Vollertsen, Filipa Ferreira and José Saldanha Matos, doi: 10.2166/wst.2017.103." Water Science and Technology 76, no. 6: 1584-1594.
Over the last decades, considerable progress has been made in the understanding of the sulfur cycle in sewer systems. In spite of a wealth of experimental and field studies that have addressed the release of hydrogen sulfide from free surface flows in gravity sewers and the corresponding air-water mass transfer, little is known about hydrogen sulfide emission under highly turbulent conditions (e.g., drop structures, hydraulic jumps). In this study, experimental work was carried out to analyze the influence of characteristics of drops on reaeration. Physical models were built, mimicking typical sewer drop structures and allowing different types of drops, drop heights, tailwater depths and flow rates. In total, 125 tests were performed. Based on their results, empirical expressions translating the relationship between the mass transfer of oxygen and physical parameters of drop structures were established. Then, by applying the two-film theory with two-reference substances, the relation to hydrogen sulfide release was defined. The experiments confirmed that the choice of the type of drop structure is critical to determine the uptake/emission rates. By quantifying the air-water mass transfer rates between free-fall and backdrop types of drop, the latter resulted in considerably lower oxygen uptake rates.
Natércia Matias; Asbjørn Haaning Nielsen; Jes Vollertsen; Filipa Ferreira; José Matos. Liquid-gas mass transfer at drop structures. Water Science and Technology 2017, 75, 2257 -2267.
AMA StyleNatércia Matias, Asbjørn Haaning Nielsen, Jes Vollertsen, Filipa Ferreira, José Matos. Liquid-gas mass transfer at drop structures. Water Science and Technology. 2017; 75 (10):2257-2267.
Chicago/Turabian StyleNatércia Matias; Asbjørn Haaning Nielsen; Jes Vollertsen; Filipa Ferreira; José Matos. 2017. "Liquid-gas mass transfer at drop structures." Water Science and Technology 75, no. 10: 2257-2267.
The main objective of this paper is to demonstrate the importance of applying dynamic modelling and real energy prices on a full scale water resource recovery facility (WRRF) for the evaluation of control strategies in terms of energy costs with aeration. The Activated Sludge Model No. 1 (ASM1) was coupled with real energy pricing and a power consumption model and applied as a dynamic simulation case study. The model calibration is based on the STOWA protocol. The case study investigates the importance of providing real energy pricing comparing (i) real energy pricing, (ii) weighted arithmetic mean energy pricing and (iii) arithmetic mean energy pricing. The operational strategies evaluated were (i) old versus new air diffusers, (ii) different DO set-points and (iii) implementation of a carbon removal controller based on nitrate sensor readings. The application in a full scale WRRF of the ASM1 model coupled with real energy costs was successful. Dynamic modelling with real energy pricing instead of constant energy pricing enables the wastewater utility to optimize energy consumption according to the real energy price structure. Specific energy cost allows the identification of time periods with potential for linking WRRF with the electric grid to optimize the treatment costs, satisfying operational goals.
P. Póvoa; Adrian Oehmen; P. Inocêncio; José Matos; A. Frazão. Modelling energy costs for different operational strategies of a large water resource recovery facility. Water Science and Technology 2017, 75, 2139 -2148.
AMA StyleP. Póvoa, Adrian Oehmen, P. Inocêncio, José Matos, A. Frazão. Modelling energy costs for different operational strategies of a large water resource recovery facility. Water Science and Technology. 2017; 75 (9):2139-2148.
Chicago/Turabian StyleP. Póvoa; Adrian Oehmen; P. Inocêncio; José Matos; A. Frazão. 2017. "Modelling energy costs for different operational strategies of a large water resource recovery facility." Water Science and Technology 75, no. 9: 2139-2148.
The presence and fate of hydrogen sulfide in wastewater systems were studied in two stretches of an intercepting sewer system located in a coastal village, in Portugal. A range of hydraulic parameters were obtained and liquid and gas phase measurements were carried out, both continuously and through intensive sampling campaigns. Upstream, where flow rates were relatively low, dissolved sulfide concentrations around 12 mg S L−1 and hydrogen sulfide gas concentrations above 250 ppm were observed, along with limited corrosion damage. It is believed this is due to the low relative humidity detected along the atmosphere of the studied sewer system. Downstream, gas concentrations were always below 40 ppm. Despite that, high signs of corrosion were detected, particularly in manholes with drop structures. It is thought that condensation of spray produced by the fall is the main cause of the phenomenon. Another relevant observation was the rapid decline in dissolved sulfide contents along gravity trunk sewers following the discharge of rising mains, with loss rates as high as 40 mg S L−1 h−1. Air-flow velocities corresponded to 15–50% of wastewater flows, an observation which agrees with other authors' publications addressing relatively small pipes and moderate water flows.
Natércia Matias; Rita Ventura Matos; Filipa Ferreira; Jes Vollertsen; José Matos. Release of hydrogen sulfide in a sewer system under intermittent flow conditions: the Ericeira case study, in Portugal. Water Science and Technology 2017, 75, 1702 -1711.
AMA StyleNatércia Matias, Rita Ventura Matos, Filipa Ferreira, Jes Vollertsen, José Matos. Release of hydrogen sulfide in a sewer system under intermittent flow conditions: the Ericeira case study, in Portugal. Water Science and Technology. 2017; 75 (7):1702-1711.
Chicago/Turabian StyleNatércia Matias; Rita Ventura Matos; Filipa Ferreira; Jes Vollertsen; José Matos. 2017. "Release of hydrogen sulfide in a sewer system under intermittent flow conditions: the Ericeira case study, in Portugal." Water Science and Technology 75, no. 7: 1702-1711.
J. Pisoeiro; A. Galvão; Helena Pinheiro; Filipa Ferreira; José Matos. Determining stoichiometric parameters of detached biomass from a HSSF-CW using respirometry. Ecological Engineering 2017, 98, 388 -393.
AMA StyleJ. Pisoeiro, A. Galvão, Helena Pinheiro, Filipa Ferreira, José Matos. Determining stoichiometric parameters of detached biomass from a HSSF-CW using respirometry. Ecological Engineering. 2017; 98 ():388-393.
Chicago/Turabian StyleJ. Pisoeiro; A. Galvão; Helena Pinheiro; Filipa Ferreira; José Matos. 2017. "Determining stoichiometric parameters of detached biomass from a HSSF-CW using respirometry." Ecological Engineering 98, no. : 388-393.
Hydrogen sulfide emissions from wastewater affect human health and equipment durability, thus presenting a complex issue for utilities. Several VOC emission models have been used before to predict H2S in collection systems and water resources recovery operations, even if with restrictions. By contrast, fewer studies focus on biosolids emissions and modelling. This paper presents a dynamic modelling approach to predict H2S concentration in a tank headspace of a wastewater biosolids recovery facility. Data from one of the largest Portuguese water resources recovery facilities was collected under different facility operating modes. The developed model adequately predicted H2S concentration, with R2 values of 0.89 and 0.78, for different periods of the year, thus showing how modelling may reliably contribute to utility operation decisions.
Rita Ventura Matos; Natércia Matias; Filipa Ferreira; José Matos. Dynamic Modeling of Hydrogen Sulfide within Enclosed Environments in Biosolids Recovery Facilities. Water Environment Research 2016, 88, 2209 -2218.
AMA StyleRita Ventura Matos, Natércia Matias, Filipa Ferreira, José Matos. Dynamic Modeling of Hydrogen Sulfide within Enclosed Environments in Biosolids Recovery Facilities. Water Environment Research. 2016; 88 (12):2209-2218.
Chicago/Turabian StyleRita Ventura Matos; Natércia Matias; Filipa Ferreira; José Matos. 2016. "Dynamic Modeling of Hydrogen Sulfide within Enclosed Environments in Biosolids Recovery Facilities." Water Environment Research 88, no. 12: 2209-2218.
High quality services of wastewater treatment require a continuous assessment and improvement of the technical, environmental and economic performance. This paper demonstrates a comprehensive approach for benchmarking wastewater treatment plants (WWTPs), using performance indicators (PIs) and indices (PXs), in a ‘plan-do-check-act’ cycle routine driven by objectives. The performance objectives herein illustrated were to diagnose the effectiveness and energy performance of an oxidation ditch WWTP. The PI and PX results demonstrated an effective and reliable oxidation ditch (good–excellent performance), and a non-reliable UV disinfection (unsatisfactory–excellent performance) related with influent transmittance and total suspended solids. The energy performance increased with the treated wastewater volume and was unsatisfactory below 50% of plant capacity utilization. The oxidation ditch aeration performed unsatisfactorily and represented 38% of the plant energy consumption. The results allowed diagnosing opportunities for improving the energy and economic performance considering the influent flows, temperature and concentrations, and for levering the WWTP performance to acceptable–good effectiveness, reliability and energy efficiency. Regarding the plant reliability for fecal coliforms, improvement of UV lamp maintenance and optimization of the UV dose applied and microscreen recommissioning were suggested.
C. Silva; José Matos; M. J. Rosa. A comprehensive approach for diagnosing opportunities for improving the performance of a WWTP. Water Science and Technology 2016, 74, 2935 -2945.
AMA StyleC. Silva, José Matos, M. J. Rosa. A comprehensive approach for diagnosing opportunities for improving the performance of a WWTP. Water Science and Technology. 2016; 74 (12):2935-2945.
Chicago/Turabian StyleC. Silva; José Matos; M. J. Rosa. 2016. "A comprehensive approach for diagnosing opportunities for improving the performance of a WWTP." Water Science and Technology 74, no. 12: 2935-2945.
Sludge (or biosolids) management is highly complex and has a significant cost associated with the biosolids disposal, as well as with the energy and flocculant consumption in the sludge processing units. The sludge management performance indicators (PIs) and indices (PXs) are thus core measures of the performance assessment system developed for urban wastewater treatment plants (WWTPs). The key PIs proposed cover the sludge unit production and dry solids concentration (DS), disposal/beneficial use, quality compliance for agricultural use and costs, whereas the complementary PIs assess the plant reliability and the chemical reagents' use. A key PI was also developed for assessing the phosphorus reclamation, namely through the beneficial use of the biosolids and the reclaimed water in agriculture. The results of a field study with 17 Portuguese urban WWTPs in a 5-year period were used to derive the PI reference values which are neither inherent to the PI formulation nor literature-based. Clusters by sludge type (primary, activated, trickling filter and mixed sludge) and by digestion and dewatering processes were analysed and the reference values for sludge production and dry solids were proposed for two clusters: activated sludge or biofilter WWTPs with primary sedimentation, sludge anaerobic digestion and centrifuge dewatering; activated sludge WWTPs without primary sedimentation and anaerobic digestion and with centrifuge dewatering. The key PXs are computed for the DS after each processing unit and the complementary PXs for the energy consumption and the operating conditions DS-determining. The PX reference values are treatment specific and literature based. The PI and PX system was applied to a WWTP and the results demonstrate that it diagnosis the situation and indicates opportunities and measures for improving the WWTP performance in sludge management.
C. Silva; J. Saldanha Matos; M.J. Rosa. Performance indicators and indices of sludge management in urban wastewater treatment plants. Journal of Environmental Management 2016, 184, 307 -317.
AMA StyleC. Silva, J. Saldanha Matos, M.J. Rosa. Performance indicators and indices of sludge management in urban wastewater treatment plants. Journal of Environmental Management. 2016; 184 ():307-317.
Chicago/Turabian StyleC. Silva; J. Saldanha Matos; M.J. Rosa. 2016. "Performance indicators and indices of sludge management in urban wastewater treatment plants." Journal of Environmental Management 184, no. : 307-317.
Over the last two decades, remarkable progress in the Portuguese drinking water and wastewater services sector has been achieved. Nevertheless, it faces a serious challenge in trying to ensure long-term sustainability. There is equally scope for considerable efficiency and effectiveness gains. The national strategic plan for the period 2014–2020 has assigned a prominent role to infrastructure asset management (IAM) in the paradigm shift required in water services. This paper discusses the progress made, the critical issues and the challenges faced by the Portuguese water sector regarding IAM, based on a comparative analysis of international and national contexts. Various worldwide initiatives are presented. The main drivers to start using IAM were quite diverse. In Portugal, legislation initially contributed to attracting the attention of the sector to IAM, but LNEC, a research institute, has played a leading role in this process. The water services regulator has also been playing a very important role. The highly fragmented structure, the politicised nature of municipal water utility management and the existing accounting procedures are some of the main barriers to the spread of IAM best practices. The sector's ongoing restructuring and the new tariff regulation will be key enabling opportunities and challenges in coming years.
R. Amaral; H. Alegre; José Matos. Highlights of key international water infrastructure asset management initiatives, and trends, challenges and developments in Portugal. Water Policy 2016, 19, 128 -146.
AMA StyleR. Amaral, H. Alegre, José Matos. Highlights of key international water infrastructure asset management initiatives, and trends, challenges and developments in Portugal. Water Policy. 2016; 19 (1):128-146.
Chicago/Turabian StyleR. Amaral; H. Alegre; José Matos. 2016. "Highlights of key international water infrastructure asset management initiatives, and trends, challenges and developments in Portugal." Water Policy 19, no. 1: 128-146.
José Saldanha Matos; Antonio Monteiro; José Silva Ferreira; Filipa Ferreira; Yohann Leboeuf; Ruth Lopes; João Guimarães; Rodrigo Oliveira; António Frazão; Pedro Botelho. Controlo de inundações em meio urbano - intervenções estruturantes previstas para a cidade de Lisboa. Águas e Resíduos 2016, 83 -93.
AMA StyleJosé Saldanha Matos, Antonio Monteiro, José Silva Ferreira, Filipa Ferreira, Yohann Leboeuf, Ruth Lopes, João Guimarães, Rodrigo Oliveira, António Frazão, Pedro Botelho. Controlo de inundações em meio urbano - intervenções estruturantes previstas para a cidade de Lisboa. Águas e Resíduos. 2016; (1):83-93.
Chicago/Turabian StyleJosé Saldanha Matos; Antonio Monteiro; José Silva Ferreira; Filipa Ferreira; Yohann Leboeuf; Ruth Lopes; João Guimarães; Rodrigo Oliveira; António Frazão; Pedro Botelho. 2016. "Controlo de inundações em meio urbano - intervenções estruturantes previstas para a cidade de Lisboa." Águas e Resíduos , no. 1: 83-93.
This study aimed at analysing the performance of horizontal subsurface flow constructed wetlands (CWs) to treat combined sewer overflow (CSO). Four horizontal subsurface flow CWs, organized in two groups (A and B) each with a planted (Phragmites australis) and a non-planted bed, were loaded with simulated CSO, with group B receiving twice the hydraulic load of group A. Beds were monitored for pH, dissolved oxygen, conductivity, redox potential, chemical oxygen demand (COD), total suspended solids (TSS) and enterococci. Porosity variations were also estimated. Monitoring was conducted during spring and wintertime, with regular and irregular loading frequencies. Results showed an average treatment efficiency of 90-100 % for TSS, 60-90 % for COD and 2-6 log for enterococci. Removal rates were especially relevant in the first 24 h for COD and TSS. TSS and enterococci removal did not exhibit the influence of macrophytes or the applied hydraulic load while COD's removal efficiency was lower in the higher load group and in planted beds.
J. Pisoeiro; Ana Galvão; F. Ferreira; J. Matos. Potential for CSO treatment with horizontal flow constructed wetlands: influence of hydraulic load, plant presence and loading frequency. Environmental Science and Pollution Research 2016, 23, 20591 -20599.
AMA StyleJ. Pisoeiro, Ana Galvão, F. Ferreira, J. Matos. Potential for CSO treatment with horizontal flow constructed wetlands: influence of hydraulic load, plant presence and loading frequency. Environmental Science and Pollution Research. 2016; 23 (20):20591-20599.
Chicago/Turabian StyleJ. Pisoeiro; Ana Galvão; F. Ferreira; J. Matos. 2016. "Potential for CSO treatment with horizontal flow constructed wetlands: influence of hydraulic load, plant presence and loading frequency." Environmental Science and Pollution Research 23, no. 20: 20591-20599.
Planning for urban sanitation in developing contexts is one of the major development challenges of this century. Particularly, the relevance of a broad perspective in sanitation decision-making processes has been increasingly discussed. One possible contribution to achieve comprehensive decisions is through the use of planning guidelines, also called process guides. The present work first identified categories of relevant decision elements, namely: (a) the multi-sectoral approach, (b) the multiplicity of sustainable dimensions, (c) the system analysis perspective and (d) the co-existence of planning scales. Then, for each category, a comparative analysis of urban sanitation process guides was conducted with a focus on technology decision-making. It was found that the importance of considering those categories is increasingly reflected in process guides, although not always in a detailed supportive way. Recommendations are provided to increase the added value of process guides regarding technology selection, as well as, to better integrate them into urban planning.
A. Ramôa; C. Lüthi; J. McConville; J. Matos. Urban sanitation technology decision-making in developing countries: a critical analysis of process guides. International Journal of Urban Sustainable Development 2016, 8, 191 -209.
AMA StyleA. Ramôa, C. Lüthi, J. McConville, J. Matos. Urban sanitation technology decision-making in developing countries: a critical analysis of process guides. International Journal of Urban Sustainable Development. 2016; 8 (2):191-209.
Chicago/Turabian StyleA. Ramôa; C. Lüthi; J. McConville; J. Matos. 2016. "Urban sanitation technology decision-making in developing countries: a critical analysis of process guides." International Journal of Urban Sustainable Development 8, no. 2: 191-209.