Urban lakes are artificial systems that accomplish many functions, such as storing rainwater, avoiding flooding of adjacent urban areas and supporting recreational activities. However, their intrinsic aesthetic value is usually reduced due to eutrophication problems and anoxia processes. The objective of this study is to present the results of the water quality monitoring of a small urban lake (11264 m² and 1.5 m average depth) in Tavernes de la Valldigna (Valencia, Spain) during summer 2016.  The final aim is to determine the better parameters for monitoring urban lakes having into account budget restrictions. La Goleta lake has suffered repeated events of fish deaths and bad odors that cause the alarm of residents and tourists, especially in summer. Municipal authorities undertook a restoration project which first part was developed during the first semester of 2016. Surveillance monitoring should be financed by the Town Council, so limiting the monitored parameters to the most appropriate ones is key for guarantying long-term surveillance. The results of this study show the importance of macrophyte community in determining water quality and maintaining dissolved oxygen levels. Dissolved oxygen is a key parameter easy to measure and a good indicator of lake water quality evolution. Analytical methodologies must be adapted to the high organic matter content of these systems to avoid interferences.

Microbial desalination cells (MDCs), a recent technological discovery, allow for simultaneous wastewater treatment and desalination of saline water with concurrent electricity production. The premise for MDC performance is based on the principles that bioelectrochemical (BES) systems convert wastewaters into treated effluents accompanied by electricity production and the ionic species migration (i.e. protons) within the system facilitates desalination. One major drawback with microbial desalination cells (MDCs) technology is its unsustainable cathode chamber where expensive catalysts and toxic chemicals are employed for electricity generation. Introducing biological cathodes may enhance the system performance in an environmentally-sustainable manner. This study describes the use of autothrophic microorganism such as algae and Anammox bacteria as sustainable biocatalyst/biocathode in MDCs. Three different process configurations of photosynthetic MDCs (using Chlorella vulgaris) were evaluated for their performance and energy generation potentials. Static (fed-batch, SPMDC), continuous flow (CFPMDC) and a photobioreactor MDC (PBMDC, resembling lagoon type PMDCs) were developed to study the impact of process design on wastewater treatment, electricity generation, nutrient removal, and biomass production and the results indicate that PMDCs can be configured with the aim of maximizing the energy recovery through either biomass production or bioelectricity production. In addition, the microbial community analysis of seven different samples from different parts of the anode chamber, disclosed considerable spatial diversity in microbial communities which is a critical factor in sustaining the operation of MDCs. This study provides the first proof of concept that anammox mechanism can be beneficial in enhancing the sustainability of microbial desalination cells to provide simultaneous removal of ammonium from wastewater and contribute in energy generation.

Introduction

Wastewater usually contains a great variety of hazardous organic compounds, being of special concern the so-called emerging compounds. Among these substances, the priority compounds are considered as especially toxic, showing most of them endocrine disruption effects.

The objective of this work was to evaluate the removal of caffeine from water by catalytic wet air oxidation (CWAO), using a Pt based-catalyst supported on a lignocellulosic activated carbon. The effect of the operation conditions, e.g., pressure, temperature and weight of catalyst on the removal of the contaminant and Total Organic Carbon was studied.

MATERIALS AND METHODS

The tested catalytic support was based on a mesoporous activated carbon synthesized from peach stones by chemical activation using H₃PO₄ solution. The active phase of the catalyst was platinum with a metallic content of 3%, using H₂PtCl₆x6H₂O as precursor. The metal was incorporated to the support by incipient wetness impregnation. The textural and morphological properties of the catalyst were explored. The tested operation conditions were the total pressure (20-40 bar), temperature (130-170 ºC) and the weight of catalyst (0.1-0.3 g). The sample analysis were carried out by using HPLC technique.

RESULTS AND DISCUSSION

N₂ adsorption-desorption isotherm of the catalyst can be classified as IV-type, characteristic of mesoporous solids. The specific surface area of the catalyst was of 1100 m².g^-1. BET area decreased after the CWAO process until 900 m².g^-1, probably due to the formation of a carbon deposit on the catalyst surface. Referring to the CWAO process, caffeine and TOC concentration gradually decreased along the reaction time, reaching to a final conversion, after 180 min, of 78-94% and 14-72%, respectively and depending on the reaction temperature.

CONCLUSIONS

The results of the study showed that CWAO of caffeine and TOC in water was successfully carried out using Pt(3%)/activated carbon as catalyst at the tested conditions. This material provides an efficient removal of caffeine, a trace compound of the domestic wastewater pollution.

ACKNOWLEDGEMENTS

The authors gratefully acknowledge the financial support from Ministerio de Economía y Competitividad Contact CTM2014-53485-REDC TRAGUANET, CTQ2014-59011-R REMEWATER and by Comunidad de Madrid through REMTAVARES Network S2013/MAE-2716.

The presence of pollutants known as emerging contaminants in water and wastewater is a topic of growing interest. Emerging contaminants, which include endocrine disrupting chemicals (EDCs) and pharmaceutical and personal care products (PPCPs), are compounds that remain relatively unknown, although their adverse effects have been proven. Emerging contaminants are not satisfactorily removed by traditional treatment methods; therefore, there is a need for innovative techniques. Advanced oxidation processes (AOPs) have been recognized as successful removal methods for these problematic pollutants. However, technical success is not the only factor that must be considered. Process engineering, environmental, and economic and social parameters were considered. A holistic analysis was completed using a ranking system to determine the performance of several AOPs (ozonation, UV, photocatalysis, the Fenton reaction, and integrated processes). Ultimately, H2O2/O3 presented the highest average ranking (3.45), with the other processes showing similar performance, with the exception of TiO2 photocatalysis (2.11).

The objective of study is to understand challenges in assessing risk due to exposures of mixture of polymers released into water during reuse and recycling activities of plastic materials on human health. A four- step human health risk assessment framework consist of hazard identification, dose response assessment, risk estimation, uncertainty characterization was developed for assessing risk. Mixture of Bisphenol A (BPA) and Di (2-ethylhexyl) phthalate (DEHP): endocrine disrupting substances was taken as an example. Both of these chemicals are used in packaging bottles, beverage and food containers and are probable to occur in water cycle simultaneously, and thus, assessment of their combined risk is required. Information on co-occurrence of these chemicals in water medium, their associated toxic effects to human were obtained from published reports and current knowledge gaps were identified. Findings of this study indicated that there exists data gaps in (1) lack of information on simultaneous exposure of two chemicals,  (2) their combined mode of action,  (3) mixture toxicity dose and concentration  dose- response relationships, (4) lack of knowledge about interaction of chemicals (5) variation of exposure with time and location, (6) complex effects at different level and segments of  community, including indirect effects on ecosystem These identified data gaps need to be filled by conducting more research in this direction so that exposure of population to polymeric compounds and chemicals in water from plastic waste can be estimated with more confidence and efforts for protecting them can be made. This information is required in properly understanding toxic effects of mixture of plastic compounds on human health.

INTRODUCTION

Nowadays the number of hazardous compounds occurring in the water environment is increasing. The substances called as priority compounds, detailed in the Water Framework Directive (2000/60/CE), are of special concern; pesticides such as isoproturon are included in this category.

The objective of this experimental work was to evaluate the removal of isoproturon from water by adsorption onto a commercial activated carbon. Equilibrium and dynamic adsorption experiments were carried out.

MATERIALS AND METHODS

Isoproturon was used in the experiments without any further purification. Ultrapure water was used in the adsorption tests. Granular activated carbon supplied by Calgon was used in the study.

Batch adsorption experiments were accomplished, in order to study the kinetic and equilibrium adsorption data. Therefore, fixed-bed adsorption tests were carried out, obtaining the breakthrough curves of the system. Isoproturon concentration in the samples was determined by HPLC technique.

RESULTS AND DISCUSSION

The equilibrium time onto Calgon F400 activated carbon was achieved after 300 hours. The obtained equilibrium adsorption isotherm could be classified as L1-type, according to Giles classification, with a maximum adsorption capacity of 316 mg.g^-1.

As a result of the fixed-bed adsorption experiments, isoproturon breakthrough curves onto F400 activated carbon at different initial concentration (50-150 µg.L^-1), volumetric flow rate (2.0-3.0 mL.min^-1) and mass of adsorbent (0.1-0.3 g) were obtained. The breakthrough curves showed a low slope-profile, indicating a slow mass transport rate due to a high diffusional resistance, probably attributed to the orientation of the molecule in the inner pores and/or to the high microporous nature of the adsorbent.

CONCLUSIONS

A batch adsorption capacity of 316 mg.g^-1 and saturation adsorption capacities from 9.6 to 21.6 mg.g^-1 were obtained onto the commercial activated carbon. The hydrophobic nature and low water solubility of isoproturon molecule could enhance the affinity towards the hydrophobic surface of the carbon. The presence of an aromatic ring on its structure contributes to a higher interaction with the carbonaceous surface.

ACKNOWLEDGEMENTS

The authors gratefully acknowledge the financial support from Ministerio de Economía y Competitividad Contract CTM2014-53485-REDC-TRAGUANET, CTQ2014-59011-R REMEWATER and by Comunidad de Madrid through REMTAVARES Network S2013/MAE-2716.

This paper investigates the presence of Legionella in the water distribution systems of buildings of the University of Perugia (Italy). Further, as the genus Legionella comprises many different species and serogroups, of which L. pneumophila sg1 is the most often associated to human lung infections, a molecular characterization of the retrieved Legionella isolates is reported.

Legionella was monitored by standard methods analyzing more than 300 water samples collected from 100 taps throughout the university campus. Legionella was absent in the great majority of the samples, while it was found in only five buildings of the entire campus. Molecular analysis indicated that the contaminations were only partially ascribed to L. pneumophila sg1, as other serogroups (sg8 and sg10) as well as other species (L. taurinensis and L. anisa) were also found. Further, in only three cases the levels of contamination were above the limit at which, according to international guidelines, remedial actions are required. In particular, a thermal disinfection, i.e., raising the water temperature above the level at which Legionella cells do not survive, was applied to the hot water supply systems where high temperature could be maintained throughout. On the contrary, in a building in which Legionella contamination originated inside the heat exchanger, a chemical disinfection with silver hydrogen peroxide was carried out.

The case study herein reported indicates how a multidisciplinary approach that integrates microbiological analysis with the survey of building’s plumbing systems can lead to the definition of effective strategies for Legionella prevention and control.

Short-term water demand forecasting is a useful tool for water distribution system management. In fact, an accurate prediction of water consumptions of a network or a part of it can support the scheduling of the main devices of the network, such as pumping stations or valves.

In this paper a model for short term water demand forecasting is proposed. The model is structured in order to provide at each hour the water demand forecast for the next 24 hour basing on coefficients estimated according to a short moving window of previously observed data.

More in details, the hourly forecast is performed in two steps: in the first step the average water demand for the next 24 hours (Q24) is forecasted multiplying the average water consumption observed in the last 24 hours by a previously estimated coefficient; in the second step, the water consumption of each of the next 24 hours is forecasted multiplying the forecasted Q24 by hourly coefficients. The coefficients’ values (both the one used to forecast the Q24 and those used to forecast the hourly values) are updated at each hour on the basis of the water demands observed in the last n (e.g. n=4) weeks.

The model is applied to a real case study; the analysis of the results, and their comparison with those provided by another short term water demand forecasting model already presented in the scientific literature, highlights that the proposed model provides an accurate and robust forecast, resulting in an efficient tool for real time management of water distribution networks requiring a very small effort for its parameterization.

Water supply systems are exposed to events that affect the normal service provision. Water companies should follow their own policy rules to manage and overcome these types of threats. In this article, resilience is identified as the capacities of the system to delimit the impacts of hazardous event, which may be characterized by its severity and duration. The effects of disruptive events to the water service delivery are classified into water scarcity, discontinuity of water supply, discontinuity of hydraulic conditions and discontinuity of drinking water quality. The loss of service level is established by failure thresholds named as a standard level, a normative level, an accepted level and a critical level. These thresholds allow formulating management actions at different stages to reach the standard level of service that identifies when the systems returns to normal conditions. The global model defined by the loss of service and time is used to measure resilience by means of a resilience factor. It depends on each type of defined threat and considers the mentioned failure thresholds. The methodology is applied to a complex real-life system, managed by Canal de Isabel II Gestión (Spain) for different study cases: a drought, pipe breaks and events that affect the water quality conditions. Real data allow contrasting the protocols of management established by the water company. The methodology helps water utilities update their protocols for a certain hazard and provide useful information to plan their investments in order to improve the system resilience.

As aging infrastructures require increasing investment for providing a specific level of service to consumers, efficient replacement polices become essential. The key for a better asset management is to set criteria, methods and systems to facilitate that improvement of efficiency at the decision making process while minimizing possible service disturbance events.

 The proposed paper will describe the development of a reliable asset lifetime model as a method for improving replacement efficiency in water supply systems. In this regard, investments will be lead to previously selected elements according to its likelihood of failure and their impact in service provision to the end user. Therefore, the method presents two steps. First of all, a failure prediction model is proposed. In a second step, consequences of failures are measured in terms of service interruption impact.

 As accuracy in failure predictions is increased, renewal investments turn out to be more efficient. Thus, the model has been built through collected data from Madrid distribution network which comprises more than 17.000 km with over 400.000 water mains. The failure prediction model is founded on the statistical analysis of historical network data from over 55.000 system failures gathered during the last four years. Likewise, detailed information from more than 4.400 disturbance events, where data has been carefully recorded through field visits and laboratory essays of soil and pipe materials when failures were repaired, has contributed to its development. The study of such large series of information has allowed not only the identification of intrinsic and dynamic explanatory factors of failures but also the establishment of reliable periods for model’s calibration and validation.

 As replacement priorities change according to system conditions and previous investments, this method will provide a tool for annual forecasting the set of elements that should be renewed to minimize service disturbance.