Dynamic modeling of active regeneration in catalyzed and non-catalyzed diesel particulate filters

Particulate matter (PM) emissions standards set by the US Environmental Protection Agency (EPA) have become increasingly stringent over the years. The EPA regulation for PM in heavy duty diesel engines has been reduced to 0.01 g/bhp-hr for the year 2010. Heavy duty diesel engines make use of an aftertreatment filtration device, the Diesel Particulate Filter (DPF). DPFs are highly efficient in filtering PM (known as soot) and are an integral part of 2010 heavy duty diesel aftertreatment system. PM is accumulated in the DPF as the exhaust gas flows through it. This PM needs to be removed by oxidation periodically for the efficient functioning of the filter. This oxidation process is also known as regeneration. There are 2 types of regeneration processes, namely active regeneration (oxidation of PM by external means) and passive oxidation (oxidation of PM by internal means). Active regeneration occurs typically in high temperature regions, about 500 - 600 ��C, which is much higher than normal diesel exhaust temperatures. Thus, the exhaust temperature has to be raised with the help of external devices like a Diesel Oxidation Catalyst (DOC) or a fuel burner. The O2 oxidizes PM producing CO2 as oxidation product. In passive oxidation, one way of regeneration is by the use of NO2. NO2 oxidizes the PM producing NO and CO2 as oxidation products. The passive oxidation process occurs at lower temperatures (200 - 400 ��C) in comparison to the active regeneration temperatures. Generally, DPF substrate walls are washcoated with catalyst material to speed up the rate of PM oxidation. The catalyst washcoat is observed to increase the rate of PM oxidation. The goal of this research is to develop a simple mathematical model to simulate the PM depletion during the active regeneration process in a DPF (catalyzed and non-catalyzed). A simple, zero-dimensional kinetic model was developed in MATLAB. Experimental data required for calibration was obtained by active regeneration experiments performed on PM loaded mini DPFs in an automated flow reactor. The DPFs were loaded with PM from the exhaust of a commercial heavy duty diesel engine. The model was calibrated to the data obtained from active regeneration experiments. Numerical gradient based optimization techniques were used to estimate the kinetic parameters of the model.

Pathology working group review of histopathologic specimens from three laboratory studies of diclofenac in trout.

While the pathology peer review/pathology working group (PWG) model has long been used in mammalian toxicologic pathology to ensure the accuracy, consistency, and objectivity of histopathology data, application of this paradigm to ecotoxicological studies has thus far been limited. In the current project, the PWG approach was used to evaluate histopathologic sections of gills, liver, kidney, and/or intestines from three previously published studies of diclofenac in trout, among which there was substantial variation in the reported histopathologic findings. The main objectives of this review process were to investigate and potentially reconcile these interstudy differences, and based on the results, to establish an appropriate no observed effect concentration (NOEC). Following a complete examination of all histologic sections and original diagnoses by a single experienced fish pathologist (pathology peer review), a two-day PWG session was conducted to allow members of a four-person expert panel to determine the extent of treatment-related findings in each of the three trout studies. The PWG was performed according to the United States Environmental Protection Agency (US EPA) Pesticide Regulation (PR) 94-5 (EPA Pesticide Regulation, 1994). In accordance with standard procedures, the PWG review was conducted by the non-voting chairperson in a manner intended to minimize bias, and thus during the evaluation, the four voting panelists were unaware of the treatment group status of individual fish and the original diagnoses associated with the histologic sections. Based on the results of this review, findings related to diclofenac exposure included minimal to slightly increased thickening of the gill filament tips in fish exposed to the highest concentration tested (1,000 ��g/L), plus a previously undiagnosed finding, decreased hepatic glycogen, which also occurred at the 1,000 ��g/L dose level. The panel found little evidence to support other reported effects of diclofenac in trout, and thus the overall NOEC was determined to be >320 ��g/L. By consensus, the PWG panel was able to identify diagnostic inconsistencies among and within the three prior studies; therefore this exercise demonstrated the value of the pathology peer review/PWG approach for assessing the reliability of histopathology results that may be used by regulatory agencies for risk assessment.

A discourse-theoretic approach to negotiated rulemaking

In 1996 and in 1997, Congress ordered the Secretary of Health and Human Services to undertake a process of negotiated rulemaking, which is authorized under the Negotiated Rulemaking Act of 1990, on three separate rulemaking matters. Other Federal agencies, including the Environmental Protection Agency and the Occupational Health and Safety Administration, have also made use of this procedure. As part of the program to reinvent government, President Clinton has issued an executive order requiring federal agencies to engage in some negotiated rulemaking procedures. I present an analytic, interpretative and critical approach to looking at the statutory and regulatory provisions for negotiated rulemaking as related to issues of democratic governance surrounding the problem of delegation of legislative power. The paradigm of law delineated by J��rgen Habermas, which sets law the task of achieving social or value integration as well as integration of systems, provides the background theory for a critique of such processes. My research questions are two. First, why should a citizen obey a regulation which is the result of negotiation by directly interested parties? Second, what is the potential effect of negotiated rulemaking on other institutions for deliberative democracy? For the internal critique I argue that the procedures for negotiated rulemaking will not produce among the participants the agreement and cooperation which is the legislative intent. For the external critique I argue that negotiated rulemaking will not result in democratically-legitimated regulation. In addition, the practice of negotiated rulemaking will further weaken the functioning of the public sphere, as Habermas theorizes it, as the central institution of deliberative democracy. The primary implication is the need to mitigate further development of administrative agencies as isolated, self-regulating systems, which have been loosened from the controls of democratic governance, through the development of a robust public sphere in which affected persons may achieve mutual understanding. ^

A Study of Radon in Air and Water in Maine Schools

The transfer coefficient of radon from water to air was investigated in schools. Kitchens, bathrooms and locker rooms were studied for seven schools in Maine. Simulations were done in water-use rooms where radon in air detectors were in place. Quantities measured were radon in water (270-24500 F) and air (0-80 q), volume of water used, emissivities (0.01-0.99) and ventilation rates (0.012-0.066A). Variation throughout the room of the radon concentration was found. Values calculated for the transfer coefficient for kitchens and baths were ranged from 9.6 x to 2.0 x The transfer coefficient was calculated using these parameters and was also measured using concentrations of radon in water and air. This provides a means by which radon in air can be estimated using the transfer coefficient and the concentration in the water in other schools and it can be used to estimate the dose caused by radon released from water use. This project was partially funded by the United States Environmental Protection Agency (grant #X828l2 101-0) and by the State of Maine (grant #10A500178). These are the first measurements of this type to be done in schools in the United States.

Revising the National Ambient Air Quality Standards: The integration of science and policy

Under the Clean Air Act, Congress granted discretionary decision making authority to the Administrator of the Environmental Protection Agency (EPA). This discretionary authority involves setting standards to protect the public's health with an "adequate margin of safety" based on current scientific knowledge. The Administrator of the EPA is usually not a scientist, and for the National Ambient Air Quality Standard (NAAQS) for particulate matter (PM), the Administrator faced the task of revising a standard when several scientific factors were ambiguous. These factors included: (1) no identifiable threshold below which health effects are not manifested, (2) no biological basis to explain the reported associations between particulate matter and adverse health effects, and (3) no consensus among the members of the Clean Air Scientific Advisory Committee (CASAC) as to what an appropriate PM indicator, averaging period, or value would be for the revised standard. ^ This project recommends and demonstrates a tool, integrated assessment (IA), to aid the Administrator in making a public health policy decision in the face of ambiguous scientific factors. IA is an interdisciplinary approach to decision making that has been used to deal with complex issues involving many uncertainties, particularly climate change analyses. Two IA approaches are presented; a rough set analysis by which the expertise of CASAC members can be better utilized, and a flag model for incorporating the views of stakeholders into the standard setting process. ^ The rough set analysis can describe minimal and maximal conditions about the current science pertaining to PM and health effects. Similarly, a flag model can evaluate agreement or lack of agreement by various stakeholder groups to the proposed standard in the PM review process. ^ The use of these IA tools will enable the Administrator to (1) complete the NAAQS review in a manner that is in closer compliance with the Clean Air Act, (2) expand the input from CASAC, (3) take into consideration the views of the stakeholders, and (4) retain discretionary decision making authority. ^

Toxics Release Inventory facilities and childhood cancer: Geographic information systems based approach

Purpose. To examine the association between living in proximity to Toxics Release Inventory (TRI) facilities and the incidence of childhood cancer in the State of Texas. ^ Design. This is a secondary data analysis utilizing the publicly available Toxics release inventory (TRI), maintained by the U.S. Environmental protection agency that lists the facilities that release any of the 650 TRI chemicals. Total childhood cancer cases and childhood cancer rate (age 0-14 years) by county, for the years 1995-2003 were used from the Texas cancer registry, available at the Texas department of State Health Services website. Setting: This study was limited to the children population of the State of Texas. ^ Method. Analysis was done using Stata version 9 and SPSS version 15.0. Satscan was used for geographical spatial clustering of childhood cancer cases based on county centroids using the Poisson clustering algorithm which adjusts for population density. Pictorial maps were created using MapInfo professional version 8.0. ^ Results. One hundred and twenty five counties had no TRI facilities in their region, while 129 facilities had at least one TRI facility. An increasing trend for number of facilities and total disposal was observed except for the highest category based on cancer rate quartiles. Linear regression analysis using log transformation for number of facilities and total disposal in predicting cancer rates was computed, however both these variables were not found to be significant predictors. Seven significant geographical spatial clusters of counties for high childhood cancer rates (p<0.05) were indicated. Binomial logistic regression by categorizing the cancer rate in to two groups (<=150 and >150) indicated an odds ratio of 1.58 (CI 1.127, 2.222) for the natural log of number of facilities. ^ Conclusion. We have used a unique methodology by combining GIS and spatial clustering techniques with existing statistical approaches in examining the association between living in proximity to TRI facilities and the incidence of childhood cancer in the State of Texas. Although a concrete association was not indicated, further studies are required examining specific TRI chemicals. Use of this information can enable the researchers and public to identify potential concerns, gain a better understanding of potential risks, and work with industry and government to reduce toxic chemical use, disposal or other releases and the risks associated with them. TRI data, in conjunction with other information, can be used as a starting point in evaluating exposures and risks. ^

Industrial benzene emissions in Houston: Legal barriers to reducing a public health threat

Decades of research show that environmental exposure to the chemical benzene is associated with severe carcinogenic, hematoxic and genotoxic effects on the human body. As such, the Environmental Protection Agency (EPA) has designated the chemical as a Hazardous Air Pollutant and prescribed benzene air concentration guidelines that provide cities with an ideal ambient level to protect human health. However, in Houston, Texas, a city home to the top industrial benzene emitters in the US who undoubtedly contribute greatly to the potentially unsafe levels of ambient benzene, regulations beyond the EPA���s unenforceable guidelines are critical to protecting public health. Despite this, the EPA has failed to establish National Ambient Air Quality Standards (NAAQS) for benzene. States are thus left to regulate air benzene levels on their own; in the case of Texas, the Texas Commission on Environmental Quality (TCEQ) and state legislature have failed to proactively develop legally enforceable policies to reduce major source benzene emissions. This inaction continues to exacerbate a public health problem, which may only be solved through a legal framework that restricts preventable benzene emissions to protect human health and holds industrial companies accountable for violations of such regulations and standards. This analysis explores legal barriers that the City of Houston and other relevant agencies currently face in their attempt to demand and bring about such change. ^

An evaluation of the Cypress Creek watershed for inorganic chemical load as it flows into Lake Houston

Background. The Cypress Creek is one of the main tributaries of Lake Houston, which provides drinking water to 21.4 million customers. Furthermore, the watershed is being utilized for contact and non-contact recreation, such as canoeing, swimming, hiking trail, and picnics. Water along the creek is impacted by numerous wastewater outfalls from both point and non-point sources. As the creek flows into Lake Houston, it carries both organic and inorganic contaminants that may affect the drinking water quality of this important water source reservoir. Objective. This study was carried out to evaluate the inorganic chemical load of the water in Cypress Creek along its entire length, from the headwaters in Waller County and up to the drainage into Lake Houston. The purpose was to determine whether there are hazardous concentrations of metals in the water and what would be the likely sources. Method. Samples were collected at 29 sites along the creek and analyzed for 29 metals, 17 of which were on the Environmental Protection Agency priority pollution list. Public access sites primarily at bridges were used for sample collection. Samples were transported on ice to the University Of Texas School Of Public Health laboratory, spiked with 2 ml HNO3 kept overnight in the refrigerator, and the following day transported to the EPA laboratory for analysis. Analysis was done by EPA Method 200.7-ICP, Method 200.8ICP/MS and Method 245.1-CVAAS. Results. Metals were present above the detection limits at 65% of sites. Concentrations of aluminum, iron, sodium, potassium, magnesium, and calcium, were particularly high at all sites. Aluminum, sodium, and iron concentrations greatly exceeded the EPA secondary drinking water standards at all sites. ^ Conclusion. The recreational water along Cypress Creek is impacted by wastewater from both permitted and non-permitted outfalls, which deposit inorganic substances into the water. Although a number of inorganic contaminants were present in the water, toxic metals regulated by the EPA were mostly below the recommended limits. However, high concentrations of aluminum, sodium, and iron in the Cypress Creek bring forward the issue of unauthorized discharges of salt water from mining, as well as industrial and domestic wastewater.^

A standard operation procedure and a pilot water testing for herbicides in northwest Harris County, Texas

Herbicides are used to control the growth of weeds along highways, power lines, and many other urban locations. Exposure to herbicides has been linked to adverse health outcomes. This study was initiated to pretest for the presence of herbicides in multiple water sources near intersections in a corridor in the Northwest Harris County (specifically in the Highway 6/FM 1960, North Freeway 45, US 290 and S 99 corridor). Roadside water and tap water samples were collected and analyzed for herbicides using the established Environmental Protection Agency (EPA) Method 515.4: "Determination of Chlorinated Acids in Drinking Water by Liquid-Liquid Micro-extraction, Derivatization, and Fast Gas Chromatography with Electron Capture Detection." A standard operating procedure (adapted from the US EPA Method 515.4) was developed for subsequent, larger studies of environmental fate of herbicides and non-occupational exposure risks. Preliminary testing of 16 water samples was performed to pretest the existence of trace herbicides; all concentrations that were greater than the minimum reporting limits of each analyte are reported with a 99 percent confidence. This study failed to find concentrations above the limits of detection of the method in any of the samples collected on June 15, 2008. However, this does not indicate that the waters around the NW Harris County are free of herbicides and metabolites. A larger and repeated sampling in the region would be necessary to make that claim. ^

A cross-sectional analysis of the association between polycyclic aromatic hydrocarbons and diesel particulate matter exposures and hypertension among individuals of Mexican origin residing in Houston, TX

Background. Research has shown that elevations of only 10 mmHg diastolic blood pressure (BP) and 5 mmHg systolic BP are associated with substantial (as large as 50%) increases in risks for cardiovascular disease, a leading cause of death, worldwide. Epidemiological studies have found that particulate matter (PM) increases blood pressure (BP) and many biological mechanisms which may suggest that the organic matter of PM contributes to the increase in BP. To understand components of PM which may contribute to the increase in BP, this study focuses on diesel particulate matter (DPM) and polycyclic aromatic hydrocarbons (PAHs). To our knowledge, there have been only four epidemiological studies on BP and DPM, and no epidemiological studies on BP and PAHs. ^ Objective. Our objective was to evaluate the association between prevalent hypertension and two ambient exposures: DPM and PAHs amongst the Mano a Mano cohort. ^ Methods. The Mano a Mano cohort which was established by the M.D. Anderson Cancer Center in 2001, is comprised of individuals of Mexican origin residing in Houston, TX. Using geographical information systems, we linked modeled annual estimates of PAHs and DPM at the census track level from the U.S. Environmental Protection Agency's National-Scale Air Toxics Assessment to residential addresses of cohort members. Mixed-effects logistic regression models were applied to determine associations between DPM and PAHs and hypertension while adjusting for confounders. ^ Results. Ambient levels of DPM, categorized into quartiles, were not statistically associated with hypertension and did not indicate a dose response relationship. Ambient levels of PAHs, categorized into quartiles, were not associated with hypertension, but did indicate a dose response relationship in multiple models (for example: Q2: OR = 0.98; 95% CI, 0.73���1.31, Q3: OR = 1.08; 95% CI, 0.82���1.41, Q4: OR = 1.26; 95% CI, 0.94���1.70). ^ Conclusion. This is the first assessment to analyze the relationship between ambient levels of PAHs and hypertension and it is amongst a few studies investigating the association between ambient levels of DPM and hypertension. Future analyses are warranted to explore the effects DPM and PAHs using different categorizations in order to clarify their relationships with hypertension.^

Associations between ambient levels of combustion pollutants and small for gestational age infants in Texas

There is scant evidence regarding the associations between ambient levels of combustion pollutants and small for gestational age (SGA) infants. No studies of this type have been completed in the Southern United States. The main objective of the project presented was to determine associations between combustion pollutants and SGA infants in Texas using three different exposure assessments. ^ Birth certificate data that contained information on maternal and infant characteristics were obtained from the Texas Department of State Health Services (TX DSHS). Exposure assessment data for the three aims came from: (1) U.S. Environmental Protection Agency (EPA) National Air Toxics Assessment (NATA), (2) U.S. EPA Air Quality System (AQS), and (3) TX Department of Transportation (DOT), respectively. Multiple logistic regression models were used to determine the associations between combustion pollutants and SGA. ^ For the first study looked at annual estimates of four air toxics at the census tract level in the Greater Houston Area. After controlling for maternal race, maternal education, tobacco use, maternal age, number of prenatal visits, marital status, maternal weight gain, and median census tract income level, adjusted ORs and 95% confidence intervals (CI) for exposure to PAHs (per 10 ng/m3), naphthalene (per 10 ng/m3), benzene (per 1 ��g/m3), and diesel engine emissions (per 10 ��g/m3) were 1.01 (0.97���1.05), 1.00 (0.99���1.01), 1.01 (0.97���1.05), and 1.08 (0.95���1.23) respectively. For the second study looking at Hispanics in El Paso County, AORs and 95% confidence intervals (CI) for increases of 5 ng/m3 for the sum of carcinogenic PAHs (�� c-PAHs), 1 ng/m3 of benzo[a]pyrene, and 100 ng/m3 in naphthalene during the third trimester of pregnancy were 1.02 (0.97���1.07), 1.03 (0.96���1.11), and 1.01 (0.97���1.06), respectively. For the third study using maternal proximity to major roadways as the exposure metric, there was a negative association with increasing distance from a maternal residence to the nearest major roadway (Odds Ratio (OR) = 0.96; 95% CI = 0.94���0.97) per 1000 m); however, once adjusted for covariates this effect was no longer significant (AOR = 0.98; 95% CI = 0.96���1.00). There was no association with distance weighted traffic density (DWTD). ^ This project is the first to look at SGA and combustion pollutants in the Southern United States with three different exposure metrics. Although there was no evidence of associations found between SGA and the air pollutants mentioned in these studies, the results contribute to the body of literature assessing maternal exposure to ambient air pollution and adverse birth outcomes. ^

Maternal exposure to hazardous air pollutants and oral clefts among offspring: Texas, 1999-2008

Birth defects are a leading cause of infant mortality in the United States. About one in 33 births in the United States is diagnosed with birth defects. Common birth defects include neural tube defects, Down syndrome and oral clefts. The present study focused on oral clefts. ^ Oral clefts refer to the malformation of lip, mouth or both. Birth prevalence of oral clefts in Texas is about 11 per 10,000 births. Etiologically, oral clefts have been classified into two groups, cleft lip with or without cleft palate (CL��P) and isolated cleft palate (CP). In spite of their high prevalence and clinical significance, the etiology of oral clefts in humans has not been well understood. Though a number of risk factors have been identified in epidemiological studies, most of them do not explain the majority of the cases. The need to identify novel risk factors associated with oral clefts provided the motivation for this study. The present study focused on maternal exposure to several hazardous air pollutants. A common subgroup of hazardous air pollutants is the volatile organic compounds found in petroleum derivatives. Four important hydrocarbons in this group are benzene, toluene, ethyl benzene and xylenes (BTEX). ^ The specific aim of this study was to evaluate the association between maternal exposure to environmental levels of BTEX and oral clefts among offspring in Texas for the period 1999-2008. ^ A case-control study design was used to assess if maternal exposure to BTEX increased the risk of oral clefts. The Texas Birth Defects Registry provided data on cases of non-syndromic oral clefts delivered in Texas during the period 1999-2008. Census tract level maternal exposure to BTEX concentrations were obtained from the Hazardous Air Pollutant Exposure Model (HAPEM) developed by the U.S. Environmental Protection Agency. Unconditional logistic regression was used to assess the relationship between maternal exposure to BTEX levels and risk of oral clefts in offspring. ^ In the selected population, mothers who had high estimated exposure to any of the BTEX compounds were not more likely to deliver an offspring with oral clefts. Future research efforts will focus on additional birth defects and thorough assessment of additional potential confounders.^

Incidencia del agua consumida en la zona de influencia del centro de salud n�� 127 El Cortaderal, como determinante de prevalencia de hipertensi��n arterial en sus habitantes, Malarg��e, 2011

La EPA (Environmental Protection Agency) ha establecido est��ndares de seguridad para m��s de 80 contaminantes que pueden encontrarse en el agua potable y presentan un riesgo a la salud humana. Los efectos agudos ocurren dentro de unas horas o d��as posteriores al momento en que la persona consume un contaminante. Casi todos los contaminantes pueden tener un efecto agudo si se consume en niveles extraordinariamente altos en el agua potable, en esos casos los contaminantes m��s probables que causen efectos agudos son las bacterias y virus. Los contaminantes en el agua potable que pueden causar efectos cr��nicos son los qu��micos (tales como solventes y plaguicidas), radionucl��idos (tal como el radio) y minerales (tal como el ars��nico y algunas sales). Entre los ejemplos de efectos cr��nicos de los contaminantes del agua potable, est��n el c��ncer, problemas del h��gado o ri��ones o dificultades en la reproducci��n. Este estudio persigue los siguientes objetivos: -Determinar si las caracter��sticas del agua de consumo de El Manzano son determinante de la alta prevalencia de HTA entre sus habitantes -Conocer las caracter��sticas f��sicas de la composici��n del agua de consumo del Paraje El Cortaderal. -Comparar la calidad del agua de consumo de las localidades de El Cortaderal y El Manzano. -Comparar si los h��bitos alimenticios de los parajes estudiados presentan diferencias significativas que pudieran incidir en la aparici��n de las Patolog��as como la HTA y la Fluorosis

PM2.5, PM10, and PM10-associated elements in the air in Bamako, Mali (2012-2013)

Saharan dust incursions and particulates emitted from human activities degrade air quality throughout West Africa, especially in the rapidly expanding urban centers in the region. Particulate matter (PM) that can be inhaled is strongly associated with increased incidence of and mortality from cardiovascular and respiratory diseases and cancer. Air samples collected in the capital of a Saharan-Sahelian country (Bamako, Mali) between September 2012 - July 2013 were found to contain inhalable PM concentrations that exceeded World Health Organization (WHO) and US Environmental Protection Agency (USEPA) PM2.5 and PM10 24-h limits 58 - 98% of days and European Union (EU) PM10 24-h limit 98% of days. Mean concentrations were 1.2-to-4.5 fold greater than existing limits. Inhalable PM was enriched in transition metals, known to produce reactive oxygen species and initiate the inflammatory reaction, and other potentially bioactive and biotoxic metals/metalloids. Eroded mineral dust composed the bulk of inhalable PM, whereas most enriched metals/metalloids were likely emitted from oil combustion, biomass burning, refuse incineration, vehicle traffic, and mining activities. Human exposure to inhalable PM and associated metals/metalloids over 24-h was estimated. The findings indicate that inhalable PM in the Sahara-Sahel region may present a threat to human health, especially in urban areas with greater inhalable PM and transition metal exposure.

La reutilizaci��n de efluentes depurados en Espa��a: retrospectiva, desarrollo del marco normativo, estudio de las tecnolog��as de regeneraci��n frente a los biorreactores de membrana y sus costes en funci��n del uso

La reutilizaci��n de efluentes depurados siempre ha sido una opci��n en lugares con d��ficit coyuntural o estructural de recursos h��dricos, se haya o no procedido a la regulaci��n y planificaci��n de esta pr��ctica. La necesidad se crea a partir de las demandas de una zona, normalmente riego agr��cola, que ven un mejor desarrollo de su actividad por contar con este recurso. Espa��a es el pa��s de la UE que m��s caudal reutiliza, y est�� dentro de los diez primeros a nivel mundial. La regulaci��n de esta pr��ctica por el RD 1620/2007, ayud�� a incorporar la reutilizaci��n de efluentes depurados a la planificaci��n hidrol��gica como parte de los programas de medidas, con objeto de mitigar presiones, como son las extracciones de agua superficial y subterr��nea, o mejoras medioambientales evitando un vertido. El objeto de este trabajo es conocer la situaci��n de la reutilizaci��n de efluentes depurados en Espa��a, los diferentes escenarios y planteamientos de esta actividad, el desarrollo del marco normativo y su aplicabilidad, junto a los tratamientos que permiten alcanzar los l��mites de calidad establecidos en la normativa vigente, en funci��n de los distintos usos. Adem��s, se aporta un an��lisis de costes de las distintas unidades de tratamiento y tipolog��as de l��neas de regeneraci��n, tanto de las utilizadas despu��s de un tratamiento secundario como de otras opciones de depuraci��n, como son los biorreactores de membrana (MBRs). Para el desarrollo de estos objetivos, en primer lugar, se aborda el conocimiento de la situaci��n de la reutilizaci��n en Espa��a a trav��s de una base de datos dise��ada para cubrir todos los aspectos de esta actividad: datos de la estaci��n depuradora de aguas residuales (EDAR), de la estaci��n regeneradora (ERA), caudales depurados, reutilizados, vol��menes utilizados y ubicaci��n de los distintos usos, tipos de l��neas de tratamiento, calidades del agua reutilizada, etc. Las principales fuentes de informaci��n son las Confederaciones Hidrogr��ficas (CCHH) a trav��s de las concesiones de uso del agua depurada, las entidades de saneamiento y depuraci��n de las distintas comunidades aut��nomas (CCAA), ayuntamientos, Planes Hidrol��gicos de Cuenca (PHC) y visitas a las zonas m��s emblem��ticas. Adem��s, se revisan planes y programas con el fin de realizar una retrospectiva de c��mo se ha ido consolidando y desarrollando esta pr��ctica en las distintas zonas de la geograf��a espa��ola. Se han inventariado 322 sistemas de reutilizaci��n y 216 tratamientos de regeneraci��n siendo el m��s extendido la filtraci��n mediante filtro arena seguido de una desinfecci��n mediante hipoclorito, aunque este tratamiento se ha ido sustituyendo por un f��sico-qu��mico con decantaci��n lamelar, filtro de arena y radiaci��n ultravioleta, tratamiento de regeneraci��n convencional (TRC), y otros tratamientos que pueden incluir membranas, tratamientos de regeneraci��n avanzados (TRA), con dosificaci��n de hipoclorito como desinfecci��n residual, para adaptarse al actual marco normativo. El uso m��s extendido es el agr��cola con el 70% del caudal total reutilizado, estimado en 408 hm3, aunque la capacidad de los tratamientos de regeneraci��n esperada para 2015, tras el Plan Nacional de Reutilizaci��n de Aguas (PNRA), es tres veces superior. Respecto al desarrollo normativo, en las zonas donde la reutilizaci��n ha sido pionera, las administraciones competentes han ido desarrollando diferentes recomendaciones de calidad y manejo de este tipo de agua. El uso agr��cola, y en zonas tur��sticas, el riego de campos de golf, fueron los dos primeros usos que tuvieron alg��n tipo de recomendaci��n incluso reglamentaci��n. Esta situaci��n inicial, sin una normativa a nivel estatal ni recomendaciones europeas, cre�� cierta incertidumbre en el avance de la reutilizaci��n tanto a nivel de concesiones como de planificaci��n. En la actualidad sigue sin existir una normativa internacional para la reutilizaci��n y regeneraci��n de efluentes depurados. Las recomendaciones de referencia a nivel mundial, y en concreto para el uso agr��cola, son las de la OMS (Organizaci��n Mundial de la Salud) publicadas 1989, con sus posteriores revisiones y ampliaciones (OMS, 2006). Esta norma combina tratamientos b��sicos de depuraci��n y unas buenas pr��cticas basadas en diferentes niveles de protecci��n para evitar problemas sanitarios. Otra normativa que ha sido referencia en el desarrollo del marco normativo en pa��ses donde se realiza esta pr��ctica, son las recomendaciones dadas por la Agencia Medioambiente Estadunidense (USEPA, 2012) o las publicadas por el Estado de California (T��tulo 22, 2001). Estas normas establecen unos indicadores y valores m��ximos d��nde el tratamiento de regeneraci��n es el responsable de la calidad final en funci��n del uso. Durante 2015, la ISO trabajaba en un documento para el uso urbano donde se muestra tanto los posibles par��metros que habr��a que controlar como la manera de actuar para evitar posibles riesgos. Por otro lado, la Comisi��n Europea (CE) viene impulsando desde el 2014 la reutilizaci��n de aguas depuradas dentro del marco de la Estrategia Com��n de Implantaci��n de la Directiva Marco del Agua, y fundamentalmente a trav��s del grupo de trabajo de ���Programas de medidas���. Para el desarrollo de esta iniciativa se est�� planteando sacar para 2016 una gu��a de recomendaciones que podr��a venir a completar el marco normativo de los distintos Estados Miembros (EM). El Real Decreto 1620/2007, donde se establece el marco jur��dico de la reutilizaci��n de efluentes depurados, tiende m��s a la filosof��a implantada por la USEPA, aunque la UE parece m��s partidaria de una gesti��n del riesgo, donde se establecen unos niveles de tolerancia y unos puntos de control en funci��n de las condiciones socioecon��micas de los distintos Estados, sin entrar a concretar indicadores, valores m��ximos o tratamientos. Sin embargo, en la normativa estadounidense se indican una serie de tratamientos de regeneraci��n, mientras que, en la espa��ola, se hacen recomendaciones a este respecto en una Gu��a sin validez legal. Por tanto, queda sin regular los procesos para alcanzar estos est��ndares de calidad, pudiendo ser ��stos no apropiados para esta pr��ctica. Es el caso de la desinfecci��n donde el uso de hipoclorito puede generar subproductos indeseables. En la Gu��a de recomendaciones para la aplicaci��n del RD, publicada por el Ministerio de Agricultura y Medioambiente (MAGRAMA) en 2010, se aclaran cuestiones frecuentes sobre la aplicaci��n del RD, prescripciones t��cnicas b��sicas para los sistemas de reutilizaci��n, y buenas pr��cticas en funci��n del uso. Aun as��, el RD sigue teniendo deficiencias en su aplicaci��n siendo necesaria una revisi��n de la misma, como en las frecuencias de muestreo incluso la omisi��n de algunos par��metros como huevos de nematodos que se ha demostrado ser inexistentes tras un tratamiento de regeneraci��n convencional. En este sentido, existe una tendencia a nivel mundial a reutilizar las aguas con fines de abastecimiento, incluir indicadores de presencia de virus o protozoos, o incluir ciertas tecnolog��as como las membranas u oxidaciones avanzadas para afrontar temas como los contaminantes emergentes. Otro de los objetivos de este trabajo es el estudio de tipolog��as de tratamiento en funci��n de los usos establecidos en el RD 1620/2007 y sus costes asociados, siendo base de lo establecido a este respecto en la Gu��a y PNRA anteriormente indicados. Las tipolog��as de tratamiento propuestas se dividen en l��neas con capacidad de desalar y las que no cuentan con una unidad de desalaci��n de aguas salobres de ��smosis inversa o electrodi��lisis reversible. Se realiza esta divisi��n al tener actuaciones en zonas costeras donde el agua de mar entra en los colectores, adquiriendo el agua residual un contenido en sales que es limitante en algunos usos. Para desarrollar este objetivo se han estudiado las unidades de tratamiento m��s implantadas en ERAs espa��olas en cuanto a fiabilidad para conseguir determinada calidad y coste, tanto de implantaci��n como de explotaci��n. El TRC, tiene un coste de implantaci��n de 28 a 48 ���.m-3.d y de explotaci��n de 0,06 a 0,09 ���. m-3, mientras que, si se precisara desalar, este coste se multiplica por diez en la implantaci��n y por cinco en la explotaci��n. En caso de los usos que requieren de TRA, como los domiciliarios o algunos industriales, los costes ser��an de 185 a 398 ���.m-3.d en implantaci��n y de 0,14 a 0,20 ���.m-3 en explotaci��n. En la selecci��n de tecnolog��as de regeneraci��n, la capacidad del tratamiento en relaci��n al coste es un indicador fundamental. Este trabajo aporta curvas de tendencia coste-capacidad que sirven de herramienta de selecci��n frente a otros tratamientos de regeneraci��n de reciente implantaci��n como son los MBR, u otros como la desalaci��n de agua de mar o los trasvases entre cuencas dentro de la planificaci��n hidrol��gica. En Espa��a, el aumento de las necesidades de agua de alta calidad en zonas con recursos escasos, aumento de zonas sensibles como puntos de captaci��n para potables, zonas de ba��o o zonas de producci��n pisc��cola, y en ocasiones, el escaso terreno disponible para la implantaci��n de nuevas plantas depuradoras (EDARs), han convertido a los MBRs, en una opci��n dentro del marco de la reutilizaci��n de aguas depuradas. En este trabajo, se estudia esta tecnolog��a frente a los TRC y TRA, aportando igualmente curvas de tendencia coste-capacidad, e identificando cuando esta opci��n tecnol��gica puede ser m��s competitiva frente a los otros tratamientos de regeneraci��n. Un MBR es un tratamiento de depuraci��n de fangos activos donde el decantador secundario es sustituido por un sistema de membranas de UF o MF. La calidad del efluente, por tanto, es la misma que el de una EDAR seguida de un TRA. Los MBRs aseguran una calidad del efluente para todos los usos establecidos en el RD, incluso dan un efluente que permite ser directamente tratado por las unidades de desalaci��n de OI o EDR. La implantaci��n de esta tecnolog��a en Espa��a ha tenido un crecimiento exponencial, pasando de 13 instalaciones de menos de 5.000 m3. d-1 en el 2006, a m��s de 55 instalaciones en operaci��n o construcci��n a finales del 2014, seis de ellas con capacidades por encima de los 15.000 m3. d-1. Los sistemas de filtraci��n en los MBR son los que marcan la operaci��n y dise��o de este tipo de instalaciones. El sistema m��s implantado en Espa��a es de membrana de fibra hueca (MFH), sobre todo para instalaciones de gran capacidad, destacando Zenon que cuenta con el 57% de la capacidad total instalada. La segunda casa comercial con mayor n��mero de plantas es Kubota, con membranas de configuraci��n placa plana (MPP), que cuenta con el 30 % de la capacidad total instalada. Existen otras casas comerciales implantadas en MBR espa��oles como son Toray, Huber, Koch o Microdym. En este documento se realiza la descripci��n de los sistemas de filtraci��n de todas estas casas comerciales, aportando informaci��n de sus caracter��sticas, par��metros de dise��o y operaci��n m��s relevantes. El estudio de 14 MBRs ha posibilitado realizar otro de los objetivos de este trabajo, la estimaci��n de los costes de explotaci��n e implantaci��n de este tipo de sistemas frente a otras alternativas de tratamiento de regeneraci��n. En este estudio han participado activamente ACA y ESAMUR, entidades p��blicas de saneamiento y depuraci��n de Catalu��a y Murcia respectivamente, que cuentan con una amplia experiencia en la explotaci��n de este tipo de sistemas. Este documento expone los problemas de operaci��n encontrados y sus posibles soluciones, tanto en la explotaci��n como en los futuros dise��os de este tipo de plantas. El trabajo concluye que los MBRs son una opci��n m��s para la reutilizaci��n de efluentes depurados, siendo ventajosos en costes, tanto de implantaci��n como de explotaci��n, respecto a EDARs seguidas de TRA en capacidades por encima de los 10.000 m3.d-1. ABSTRACT The reuse of treated effluent has always been an option in places where a situational or structural water deficit exists, whether regulatory and/or planning efforts are completed or not. The need arises from the demand of a sector, commonly agricultural irrigation, which benefits of this new resource. Within the EU, Spain is ahead in the annual volume of reclaimed water, and is among the top ten countries at a global scale. The regulation of this practice through the Royal Decree 1620/2007 has helped to incorporate the water reuse to the hydrological plans as a part of the programme of measures to mitigate pressures such as surface or ground water extraction, or environmental improvements preventing discharges. The object of this study is to gain an overview of the state of the water reuse in Spain, the different scenarios and approaches to this activity, the development of the legal framework and its enforceability, together with the treatments that achieve the quality levels according to the current law, broken down by applications. Additionally, a cost analysis of technologies and regeneration treatment lines for water reclamation is performed, whereas the regeneration treatment is located after a wastewater treatment or other options such as membrane bioreactors (MBR). To develop the abovementioned objectives, the state of water reuse in Spain is studied by means of a database designed to encompass all aspects of the activity: data from the wastewater treatment plants (WWTP), from the water reclamation plants (WRP), the use of reclaimed water, treated water and reclaimed water annual volumes and qualities, facilities and applications, geographic references, technologies, regeneration treatment lines, etc. The main data providers are the River Basin authorities, through the concession or authorization for water reuse, (sanitary and wastewater treatment managers from the territorial governments, local governments, Hydrological Plans of the River Basins and field visits to the main water reuse systems. Additionally, a review of different plans and programmes on wastewater treatment or water reuse is done, aiming to put the development and consolidation process of this activity in the different regions of Spain in perspective. An inventory of 322 reuse systems and 216 regeneration treatments has been gathered on the database, where the most extended regeneration treatment line was sand filtration followed by hypochlorite disinfection, even though recently it is being replaced by physical���chemical treatment with a lamella settling system, depth sand filtration, and a disinfection with ultraviolet radiation and hypochlorite as residual disinfectant, named conventional regeneration treatment (CRT), and another treatment that may include a membrane process, named advanced regeneration treatment (ART), to adapt to legal requirements. Agricultural use is the most extended, accumulating 70% of the reclaimed demand, estimated at 408 hm3, even though the expected total capacity of WRPs for 2015, after the implementation of the National Water Reuse Plan (NWRP) is three times higher. According to the development of the water reuse legal framework, there were pioneer areas where competent authorities developed different quality and use recommendations for this new resource. Agricultural use and golf course irrigation in touristic areas were the first two uses with recommendations and even legislation. The initial lack of common legislation for water reuse at a national or European level created some doubts which affected the implementation of water reuse, both from a planning and a licensing point of view. Currently there is still a lack of common international legislation regarding water reuse, technologies and applications. Regarding agricultural use, the model recommendations at a global scale are those set by the World Health Organization published in 1989, and subsequent reviews and extensions about risk prevention (WHO, 2006). These documents combine wastewater treatments with basic regeneration treatments reinforced by good practices based on different levels of protection to avoid deleterious health effects. Another relevant legal reference for this practices has been the Environmental Protection Agency of the US (USEPA, 2012), or those published by the State of California (Title 22, 2001). These establish indicator targets and maximum thresholds where regeneration treatment lines are responsible for the final quality according to the different uses. During 2015, the ISO has worked on a document aimed at urban use, where the possible parameters to be monitored together with risk prevention have been studied. On the other hand, the European Commission has been promoting the reuse of treated effluents within the Common Implementation Strategy of the Water Framework Directive, mainly through the work of the Programme of Measures Working Group. Within this context, the publication of a recommendation guide during 2016 is intended, as a useful tool to fill in the legal gaps of different Member States on the matter. The Royal Decree 1620/2007, where the water reuse regulation is set, resembles the principles of the USEPA more closely, even though the EU shows a tendency to prioritize risk assessment by establishing tolerance levels and thresholds according to socioeconomic conditions of the different countries, without going into details of indicators, maximum thresholds or treatments. In contrast, in the US law, regeneration treatments are indicated, while in the Spanish legislation, the only recommendations to this respect are compiled in a non-compulsory guide. Therefore, there is no regulation on the different treatment lines used to achieve the required quality standards, giving room for inappropriate practices in this respect. This is the case of disinfection, where the use of hypochlorite may produce harmful byproducts. In the recommendation Guide for the application of the Royal Decree (RD), published by the Ministry of Agriculture and Environment (MAGRAMA) in 2010, clarifications of typical issues that may arise from the application of the RD are given, as well as basic technical parameters to consider in reuse setups, or good practices according to final use. Even so, the RD still presents difficulties in its application and requires a review on issues such as the sampling frequency of current quality parameters or even the omission of nematode eggs indicator, which have been shown to be absent after CRT. In this regard, there is a global tendency to employ water reuse for drinking water, including indicators for the presence of viruses and protozoans, or to include certain technologies such as membranes or advanced oxidation processes to tackle problems like emerging pollutants. Another of the objectives of this study is to provide different regeneration treatment lines to meet the quality requirements established in the RD 1620/2007 broken down by applications, and to estimate establishment and operational costs. This proposal has been based on what is established in the above mentioned Guide and NWRP. The proposed treatment typologies are divided in treatment trains with desalination, like reverse osmosis or reversible electrodialisis, and those that lack this treatment for brackish water. This separation is done due to coastal facilities, where sea water may permeate the collecting pipes, rising salt contents in the wastewater, hence limiting certain uses. To develop this objective a study of the most common treatment units set up in Spanish WRPs is conducted in terms of treatment train reliability to obtain an acceptable relationship between the required quality and the capital and operational costs. The CRT has an establishment cost of 28 to 48 ���.m-3.d and an operation cost of 0.06 to 0.09 ���.m-3, while, if desalination was required, these costs would increase tenfold for implementation and fivefold for operation. In the cases of uses that require ART, such as residential or certain industrial uses, the costs would be of 185 to 398 ���.m-3.d for implementation and of 0.14 to 0.20 ���.m-3 for operation. When selecting regeneration treatment lines, the relation between treatment capacity and cost is a paramount indicator. This project provides cost-capacity models for regeneration treatment trains. These may serve as a tool when selecting between different options to fulfill water demands with MBR facilities, or others such as sea water desalination plants or inter-basin water transfer into a water planning framework. In Spain, the requirement for high quality water in areas with low resource availability, the increasing number of sensitive zones, such as drinking water extraction, recreational bathing areas, fish protected areas and the lack of available land to set up new WWTPs, have turned MBRs into a suitable option for water reuse. In this work this technology is analyzed in contrast to CRT and ART, providing cost-capacity models, and identifying when and where this treatment option may outcompete other regeneration treatments. An MBR is an activated sludge treatment where the secondary settling is substituted by a membrane system of UF or MF. The quality of the effluent is, therefore, comparable to that of a WWTP followed by an ART. MBRs ensure a sufficient quality level for the requirements of the different uses established in the RD, even producing an effluent that can be directly treated in OI or EDR processes. The implementation of this technology in Spain has grown exponentially, growing from 13 facilities with less than 5000 m3.d-1 in 2006 to above 55 facilities operating by the end of 2014, 6 of them with capacities over 15000 m3.d-1. The membrane filtration systems for MBR are the ones that set the pace of operation and design of this type of facilities. The most widespread system in Spain is the hollow fiber membrane configuration, especially on high flow capacities, being Zenon commercial technology, which mounts up to 57% of the total installed capacity, the main contributor. The next commercial technology according to plant number is Kubota, which uses flat sheet membrane configuration, which mounts up to 30% of the total installed capacity. Other commercial technologies exist within the Spanish MBR context, such as Toray, Huber, Koch or Microdym. In this document an analysis of all of these membrane filtration systems is done, providing information about their characteristics and relevant design and operation parameters. The study of 14 full scale running MBRs has enabled to pursue another of the objectives of this work: the estimation of the implementation and operation costs of this type of systems in contrast to other regeneration alternatives. Active participation of ACA and ESAMUR, public wastewater treatment and reuse entities of Catalu��a and Murcia respectively, has helped attaining this objective. A number of typical operative problems and their possible solutions are discussed, both for operation and plant design purposes. The conclusion of this study is that MBRs are another option to consider for water reuse, being advantageous in terms of both implementation and operational costs, when compared with WWTPs followed by ART, when considering flow capacities above 10000 m3.d-1.