Molecular and geochemical basis of microbially induced carbonate precipitation for treating acid mine drainage: The case of a novel Sporosarcina genomospecies from mine tailings.

Microbially induced carbonate precipitation (MICP) immobilizes toxic metals and reduces their bioavailability in aqueous systems. However, its application in the treatment of acid mine drainage (AMD) is poorly understood. In this study, the genomes of Sporosarcina sp. UB5 and UB10 were sequenced. Urease, carbonic anhydrases, and metal resistance genes were identified and enzymatic assays were performed for their validation. The geochemical mechanism of precipitation in AMD was elucidated through geo-mineralogical analysis. Sporosarcina sp. UB5 was shown to be a new genomospecies, with an average nucleotide identity < 95 % (ANI) and DNA-DNA hybridization < 70 % (DDH) whereas UB10 is close to S. pasteurii. UB5 contained two urease operons, whereas only one was identified in UB10. The ureolytic activities of UB5 and UB10 were 122.67 ± 15.74 and 131.70 ± 14.35 mM NH4+ min-1, respectively. Both strains feature several carbonic anhydrases of the α, ß, or γ families, which catalyzed the precipitation of CaCO3. Only Sporosarcina sp. UB5 was able to immobilize metals and neutralize AMD. Geo-mineralogical analyses revealed that UB5 directly immobilized Fe (1-23 %), Mn (0.65-1.33 %) and Zn (0.8-3 %) in AMD via MICP and indirectly through adsorption to calcite and binding to bacterial cell walls. The MICP-treated AMD exhibited high removal rates (>67 %) for Ag, Al, As, Ca, Cd, Co, Cu, Fe, Mn, Pb, and Zn, and a removal rate of 15 % for Mg. This study provides new insights into the MICP process and its applications to AMD treatment using autochthonous strains.

Denim industry wastewater treatment by a heterogeneous solar-Fenton process catalyzed by Fe supported on recycled polyethylene terephthalate (PET) by ultrasonic modification.

The textile industry is an important economic sector; however, its wastewater generates a great impact on the environment. A heterogeneous solar Fenton (HSF) process was evaluated for denim wastewater treatment. The catalyst was obtained through ultrasonic modification of recycled polyethylene terephthalate (PET) with Fe nanoparticles (PET/NPs- Fe3O4). The SFH process was optimized using surface response methodology with a face-centered central composite design considering the effects of the hydraulic retention time (10, 25, and 40 min), hydrogen peroxide dosage (500, 1000, and 1500 mg/L), and mass of the packed catalyst (4, 6 and 8 g) on the color, COD, and turbidity removal efficiencies. The operating conditions for maximum COD removal were H2O2 541.7 mg/L, HRT 33.9 min, and PET/NPs- Fe3O4 dose 7.9 g with solar radiation. The removal of 91.2% COD, 86.2% color, 90.4% turbidity, and 81.9% TOC was obtained at 14.2 kJ/L QUva. PET modification yielded 1.6 mg Fe/g PET, and the modification method does not allow Fe leaching. The effluent obtained from the SFH process complies with the maximum permissible limits in Mexican legislation in terms of COD, TOC, turbidity, and color and allows the reuse of PET.

Sustainable removal of nutrients (n and p) in a wastewater treatment plant, with eggshell (biocalcium).

Biological treatments have become insufficient to treat municipal wastewater with greater toxicity and excess nitrogen and phosphate species, thus affecting the organisms that consume the water. In this work, a process was implemented for the removal of nutrients through three stages: stage A, complete aeration (24 h, 43 months); stage B, decreased aeration (12 h, 17 months); and stage C, decreased aeration with biocalcium (12 h, 19 months). The addition of biocalcium from eggshell promoted the formation of flocks, which resulted in the removal of nitrites (61 %), nitrates (84 %), total nitrogen (57 %), total phosphorus (8.3 %), sedimentable solids (50 %), total suspended solids (69 %), BOD5 (76 %), helminth eggs (50 %) and fecal coliforms (54 %). The statistical analyses in the three stages indicated that there is a strong correlation between the concentration of fats and oils and the removal of sedimentable solids and total suspended solids, since these parameters were correlated by 97 and 89 %, respectively. Sedimentable solids were correlated with total suspended solids by 94 %, while nitrates and total nitrogen were correlated 92 %, which favors the removal of nutrients in wastewater. The increase in the concentration of nitrogen in the sludge in stage C generated a C:N ratio of 7.98. This ratio shows that the sludge is feasible for use as a mediator of soils and a biofertilizer because of the high contents of calcium, phosphorus and nitrogen. In addition, biocalcium promoted the precipitation of hydroxyapatite, struvite, calcite and quartz. In general, the three stages of the treatment contributed to the stabilization of the wastewater treatment plant (WWTP) in an efficient, economical, and safe way.

Electro-galvanic alkalization and treatment of rainwater to obtain drinking water.

Rainwater Electro-Galvanic Alkalization (EGA) was performed using copper and magnesium (1:1) electrode. Efficiently removal of pollutants without external energy consumption was carried out, in addition essential ions were dosed for alkalization of rainwater. The optimal system conditions were obtained using response surface methodology (RSM) by considering the following operating variables: flow rate and concentration of the supporting electrolyte (NaCl and CaCl2). Furthermore, the maximum efficiency of nitrate, ammoniacal nitrogen, colour, and turbidity removal was evaluated. The results showed that the response variables were mainly sensitive to the type of supporting electrolyte used and the flow rate. Under experimental conditions of 0.009 M (NaCl) and 20 mL min-1, the removal rate was 74.19%, 72.49%, and 81.43% for nitrates, colour, and turbidity, respectively, and the lowest concentration of ammoniacal nitrogen (0.99mgL-1) was obtained. The kinetic models for nitrate and colour were fitted to zero-order models with k=0.33mgL-1min-1 and k=0.933Pt-Co, respectively. In addition, turbidity was fitted to a first-order model (k=0.1661min-1), and ammoniacal nitrogen was fitted to a second-order model (k=0.0217Lmg-1min-1). The concentration increases of minerals such as Ca and Mg, which rises the rainwater alkalinity after treatment (pH shift from 6.1 to 8.91), was determined by inductively coupled plasma (ICP) analysis.

Treatment of gaseous streams polluted with H2S: Comparison of electrolytic and electro-Fenton assisted absorption processes.

H2S is a gaseous compound that contributes to air pollution. In this work, the electrochemical oxidation treatment of gaseous streams polluted with H2S is evaluated using a jet mixer and electrochemical cell device, in which the performance of electrolytic and electro-Fenton assisted absorption processes are compared. Results demonstrate the feasibility of both processes to remove H2S, reaching coulombic efficiencies of nearly 100% in the electrolytic assisted absorption, and 70-80% in the electro-Fenton assisted absorption. Aqueous solutions containing phosphate salts as electrolyte were found to be suitable as absorbents for the process. Efficiency in the cathodic production of H2O2 in these solutions using the experimental device was found to be as high as 32.8% (1.184 mgH2O2/min) at 12 °C and atmospheric pressure. Sequential formation of SO2 and SO3 is obtained by the oxidation of H2S contained in the gas. These species are hydrolysed, and a part remained in the absorbent as SO32- and SO42-, while the rest is dragged in the outlet gas. SO3 production is promoted by electrolytic assisted absorption and polysulphides by the electro-Fenton technology. Low concentrations of elemental sulphur are detected in the solid suspensions formed during the process.

Acid mine drainage (AMD) treatment using galvanic electrochemical system Al-Cu.

Acid mine drainage was evaluated using a galvanic (GV) electrochemical system, Al-Cu (anode/cathode), based on a 32 factorial design. The factors analyzed were anodic area/volume ratios (A/V) of 0.037, 0.072, and 0.112 cm2/cm3, and treatment time from 0.25-8 h, and analyses were performed in duplicate with 11 degrees of freedom. The response variables were the total dissolved solids and concentrations of As, Cu, Co, Cr, Pb, Fe, Ni, and SO42-. The pH, electrical conductivity, and temperature were monitored during the process. Significant differences between treatments were determined by analysis of variance with Tukey's test (p < 0.05) using Statgraphics Centurion XVI.I software. The results showed that a greater electrode surface, A/V ratio, and treatment time improved pollutant removal. The spontaneous reactions generated by the galvanic cell, through the current that flows owing to the potential difference between the Al and Cu electrodes, allows the removal of heavy metals, arsenic, and SO42- by coagulation and precipitation mechanisms. The removal efficiencies achieved were Cu (99.1%), As (76.6%), Ni (80.2%), Pb (83.6%), Cr (100%), Fe (93.71%), and 92.9% for sulfates. The X-ray diffraction and Raman analyses of the solid fraction indicated that cuprite was formed with a purity of 96%, and the recovery of Cu by the GV system may be a viable option for mining companies.

SARS-CoV-2 pharmaceutical drugs: a critical review on the environmental impacts, chemical characteristics, and behavior of advanced oxidation processes in water.

This review summarizes research data on the pharmaceutical drugs used to treat the novel SARS-CoV-2 virus, their characteristics, environmental impacts, and the advanced oxidation processes (AOP) applied to remove them. A literature survey was conducted using the electronic databases Science Direct, Scopus, Taylor & Francis, Google Scholar, PubMed, and Springer. This complete research includes and discusses relevant studies that involve the introduction, pharmaceutical drugs used in the SARS-CoV-2 pandemic: chemical characteristics and environmental impact, advanced oxidation process (AOP), future trends and discussion, and conclusions. The results show a full approach in the versatility of AOPs as a promising solution to minimize the environmental impact associated with these compounds by the fact that they offer different ways for hydroxyl radical production. Moreover, this article focuses on introducing the fundamentals of each AOP, the main parameters involved, and the concomitance with other sources and modifications over the years. Photocatalysis, sonochemical technologies, electro-oxidation, photolysis, Fenton reaction, ozone, and sulfate radical AOP have been used to mineralize SARS-CoV-2 pharmaceutical compounds, and the efficiencies are greater than 65%. According to the results, photocatalysis is the main technology currently applied to remove these pharmaceuticals. This process has garnered attention because solar energy can be directly utilized; however, low photocatalytic efficiencies and high costs in large-scale practical applications limit its use. Furthermore, pharmaceuticals in the environment are diverse and complex. Finally, the review also provides ideas for further research needs and major concerns.

As and [Formula: see text] cooccurrence in drinking water: critical review of the international scenario, physicochemical behavior, removal technologies, health effects, and future trends.

Drinking water contaminated with As and [Formula: see text] is increasingly prevalent worldwide. Their coexistence can have negative effects due to antagonistic or synergistic mechanisms, ranging from cosmetic problems, such as skin lesions and teeth staining, to more severe abnormalities, such as cancer and neurotoxicity. Available technologies for concurrent removal include electrocoagulation ~ adsorption > membranes > chemical coagulation > , and among others, all of which have limitations despite their advantages. Nevertheless, the existence of competing ions such as silicon > phosphate > calcium ~ magnesium > sulfate > and nitrate affects the elimination efficiency. Mexico is one of the countries that is affected by As and [Formula: see text] contamination. Because only 10 of the 32 states have adequate removal technologies, more than 65% of the country is impacted by co-presence problems. Numerous reviews have been published concerning the elimination of As or [Formula: see text]. However, only a few studies have focused on the simultaneous removal. This critical review analyzes the new sources of contamination, simultaneous physicochemical behaviors, available technologies for the elimination of both species, and future trends. This highlights the need to implement technologies that work with actual contaminated water instead of aqueous solutions (55% of the works reviewed correspond to aqueous solutions). Similarly, it is necessary to migrate to the creation of pilot, pre-pilot, or prototype scale projects, because 77% of the existing studies correspond to lab-scale research.

Photo-electrooxidation treatment of Acetaminophen in aqueous solution using BDD-Fe and BDD-Cu systems.

In this study, acetaminophen (ACT) in aqueous solution was treated with electrooxidation and photo-electrooxidation processes (PEO). An electrochemical cell was used for the treatment of different concentrations of ACT (10, 50 and 80 mg L-1). A 23 factorial design was proposed, and the variables studied were current intensity 0.5 A (45.45 mA cm-2) and 1.0 A (90.91 mA cm-2), electrode configuration (anode:BDD, cathode:Fe or Cu) and presence/absence of UV light; NaCl 0.043 M (2.5 g L-1) was used as supporting electrolyte, the initial pH was 5.5, and the treatment time was 3 h. The aqueous solutions were characterized before and after the treatment using infrared spectroscopy (FT-IR), Ultraviolet-visible spectroscopy (UV-Vis), chemical oxygen demand (COD), total organic carbon (TOC), total carbon (TC), and fluorescence spectroscopy. The optimal operating conditions using an initial ACT concentration of 80 mg L-1 were 1.0 A, BDD-Fe configuration and UV light (254 nm). The removal efficiencies were 100% of ACT and 82.75% of TOC after 15 min of treatment. At concentrations of 50 and 10 mg L-1, 77.16% and 50.29% of TOC were removed after 10 and 5 min of treatment, respectively. Finally, the kinetic study showed an increase in the rate constants when the UV light was applied.

Defluoridation of drinking water by magnesium and aluminum electrocoagulation in continuous flow-rate: a response surface design.

The goal of this research is to apply an electrocoagulation process in continuous flow for the defluoridation of drinking water. Two sampling sites were studied, Temascalcingo (T), Mexico state and Jerecuaro (J), Guanajuato, with fluoride (F-) concentrations above the norms (2.3 mg L-1 and 4.5 mg L-1, respectively). In addition, a second Temascalcingo sample was enriched (TE) to 9.2 mg L-1 F- to study the effect of the F- concentration. A response surface design was proposed through a Box-Behnken model, and the variables studied were electrode system, flow-rate and current intensity. 51 experiments were performed with T-site to determine the best operating conditions for the system. These conditions were applied to the J-site. The experiments for T, Al/Al system achieves an F- concentration within permissible limits (0.72 mg L-1 F-) at 10 min of treatment, 0.2 A (Current density j 48.78 A m-2) and 10 mL min-1 with a removal efficiency of 68.69%, and after 160 min, the removal increased to 99.56%. AlMg/AlMg needs 10 min to achieve a concentration of 0.75 mg L-1 F- at 0.2 A (j 25 A m-2), 16 mL min-1 with a removal efficiency of 67.39%, and after 100 min, the removal is increased to 92.17%. An important and novel advantage is the use of AlMg allows an acceptable removal of F- (<1.5 mg L-1) at high and low concentrations in short periods of time; this also allows save energy costs and the effluent is free of residual aluminum, avoiding side effects.

Evaluation and comparison of advanced oxidation processes for the degradation of 2,4-dichlorophenoxyacetic acid (2,4-D): a review.

Organochlorine pesticides have generated public concern worldwide because of their toxicity to human health and the environment, even at low concentrations, and their persistence, being mostly nonbiodegradable. The use of 2,4-dichlorophenoxyacetic acid (2,4-D) has increased in recent decades, causing severe water contamination. Several treatments have been developed to degrade 2,4-D. This manuscript presents an overview of the physicochemical characteristics, uses, regulations, environmental and human health impacts of 2,4-D, and different advanced oxidation processes (AOPs) to degrade this organic compound, evaluating and comparing operation conditions, efficiencies, and intermediaries. Based on this review, 2,4-D degradation is highly efficient in ozonation (system O3/plasma, 99.8% in 30 min). Photocatalytic, photo-Fenton, and electrochemical processes have the optimal efficiencies of degradation and mineralization: 97%/79.67% (blue TiO2 nanotube arrays//UV), 100%/98% (Fe2+/H2O2/UV), and 100%/84.3% (MI-meso SnO2), respectively. The ozonation and electrochemical processes show high degradation efficiencies, but energy costs are also high, and photocatalysis is more expensive with a separation treatment used to recover the catalyst in the solution. The Fenton process is a viable economic-environmental option, but degradation efficiencies are often low (50-70%); however, they are increased when solar UV radiation is used (90-100%). AOPs are promising technologies for the degradation of organic pollutants in real wastewater, so evaluating their strengths and weaknesses is expected to help select viable operational conditions and obtain optimal efficiencies.

Phosphate removal from food industry wastewater by chemical precipitation treatment with biocalcium eggshell.

The physicochemical treatment (PT) of food industry wastewater was investigated. In the first stage, calcium magnesium acetate (CaMgAc4) was synthesized using eggshell (biocalcium), magnesium oxide and acetic acid in a 1:1:1 stoichiometric ratio. In the synthesis process, the thermodynamic parameters (ΔH, ΔS and ΔG) indicated that the reaction was endothermic and spontaneous. The samples were characterized by infrared spectroscopy (IR), scanning electronic microscopy (SEM), X-ray diffraction (XRD) and electron X-ray dispersive spectroscopy (EDS). CaMgAc4 was used to precipitate the phosphate matter. IR analysis revealed that the main functional groups were representative of the acetate compounds and the presence of OH- groups and carbonates. In the physicochemical treatment, a response surface design was used to determine the variables that influence the process (pH, t, and concentration), and the response variable was phosphorus removal. The treatments were carried out in the wastewater industry with an initial concentration of 658 mg/L TP. The optimal conditions of the precipitation treatment were pH 12, time 12 min, and a CaMgAc4 concentration of 13.18 mg/L. These conditions allowed the total elimination (100%) of total phosphorus and phosphates, 81.43% BOD5 and 81.0% COD, 98.9% turbidity, 95.01% color, and 92% nitrogen matter.

Industrial wastewater treatment using magnesium electrocoagulation in batch and continuous mode.

In the present study, the electrocoagulation (EC) performance of a Mg-Mg system was applied for the industrial wastewater treatment, from an industrial park that covers different activities such as: food, automotive, pharmaceutical, chemistry and cosmetics, after primary clarification. The effects of major operating parameters such as pH, reaction time, and current density were investigated for chemical oxygen demand (COD), color, and turbidity removal efficiency. The batch system was found convenient, achieving 63.52% COD, 96% color, and 99.32% turbidity removal at optimized operating conditions of pH 7.12, reaction time of 75 min, and current density of 201.5 A/m2. On the other hand, for continuous EC, the process removed approximately 46.58%, 95.96%, and 87.19% of the COD, color, and turbidity respectively, at 90 min of retention time, current density 440 A/m2, and a rate of 20 mL/min. Additionally, concerning nutrient removal (N and P), the EC system with Mg electrodes was highly efficient; batch treatment removed 97% of total phosphorus and 67% of ammoniacal nitrogen, whereas the continuous treatment removed 98.5% of total phosphorus and 83% of ammoniacal nitrogen. The sludge characterization before and after EC treatment was made by SEM, EDS, Fluorescence spectroscopy, IR spectroscopy. Minerals such as chlorite, crossite, richterite, pyroaurite, langbeinite as weel as aliphatic and polysubstituted aromatics compounds, sulfates and phosphates inorganic ions, and organic phosphorus were reduced. The energy cost in the batch EC is US$0.05/m3. A numerical CFD model was used to estimate the velocity fields and guarantee the presence of turbulent kinetic energy within a continuous flow reactor.

Assessing the viability of electro-absorption and photoelectro-absorption for the treatment of gaseous perchloroethylene.

This work focuses on the development of electro-absorption and photoelectro-absorption technologies to treat gases produced by a synthetic waste containing the highly volatile perchloroethylene (PCE). To do this, a packed absorption column coupled with a UV lamp and an undivided electrooxidation cell was used. Firstly, it was confirmed that the absorption in a packed column is a viable method to achieve retention of PCE into an absorbent-electrolyte liquid. It was observed that PCE does not only absorb but it was also transformed into phosgene and other by-products. Later, it was confirmed that the electro-absorption process influenced the PCE degradation, favoring the transformation of phosgene into final products. Opposite to what is expected, carbon dioxide is not the main product obtained, but carbon tetrachloride and trichloroacetic acid. Both species are also hazardous but their higher solubility in water opens possibilities for a successful and more environmental-friendly removal. The coupling with UV-irradiation has a negative impact on the degradation of phosgene. Finally, a reaction mechanism was proposed for the degradation of PCE based on the experimental observations. Results were not as expected during the planning of the experimental work but it is important to take in mind that PCE decomposition occurs in wet conditions, regardless of the applied technology, and this work is a first approach to try to solve the treatment problems associated to PCE gaseous waste flows in a realistic way.

PTSD Predicts Smoking Cessation Failure in a Trauma-Exposed Population.

OBJECTIVE: The objective of the study was to investigate whether a diagnosis of posttraumatic stress disorder (PTSD; full or partial) or specific PTSD symptom clusters predicted failure in quitting smoking in a trauma-exposed population. Methods: Participants were 310 smokers who attempted quitting smoking, either successfully (quitters, n = 213) or not (relapsers, n = 97), who lived in slums and were attending a family doctor program. Measurements included a general questionnaire covering sociodemographic characteristics, clinical status and life habits, and the Posttraumatic Stress Disorder Checklist - Civilian Version. Differences in sociodemographic, clinical and lifestyle characteristics between quitters and relapsers were compared using a chi-square test. Because of the small sample size, full and partial PTSD were collapsed into a single category. Results: Significant differences (p ≤ .15) between quitters and relapsers were found in age, body mass index (BMI), income, alcohol consumption, and in the presence of full/partial PTSD diagnosis and of all three symptom clusters separately. Four logistic regression models predicting smoking cessation were modeled to control for confounding factors and included as independent variables a full/partial PTSD diagnosis and the three posttraumatic symptom clusters. The avoidance/numbing cluster presented the strongest association with relapse status (ORa 2.04, 95% CI [1.15, 3.63], p = .015), followed by the full/partial PTSD (ORa 1.80, 95% CI [1.04, 3.14], p = .038). The re-experiencing and the hyperarousal clusters were non-significantly associated with smoking cessation (ORa 1.34, 95% CI [0.80, 2.31], ns and ORa 1.65, 95% CI [0.96, 2.84], ns, respectively). Conclusions: Full/partial PTSD and posttraumatic symptom clusters uniquely predict risk for smoking relapse and thus may be a useful therapeutic target in trauma-exposed smokers.

Hemodiafiltración en línea como terapia de reemplazo renal crónica. Primera experiencia nacional en el Hospital Universitario / Online haemodiafiltration therapy to treat chronic kidney disease. First national experience in the university hospital / Hemodiafiltração on line como terapia de substituição da função renal crônica. Primeira experiência nacional no hospital universitário

Resumen: La enfermedad renal crónica tiene una prevalencia estimada de 6,5% a 8% en los adultos mayores de 18 años en Uruguay. A pesar de los esfuerzos por realizar un diagnóstico temprano y retrasar su progresión un porcentaje de pacientes requiere terapia de reemplazo renal (TRR) mediante diálisis, con una tasa de incidencia anual de 166 pacientes/millón de población. A pesar de las mejoras en el cuidado nefrológico y en las técnicas de hemodiálisis, la mortalidad anual de los pacientes en esta técnica es elevada en nuestro país (16,5%) y en todo el mundo. Con el objetivo de mejorar estos aspectos se han ensayado técnicas dialíticas que asocian la convección como estrategia para depurar moléculas de mayor tamaño que habitualmente no se depuran en la hemodiálisis convencional. La hemodiafiltración en línea (HDF-OL) es una técnica convectiva. Cuando se utiliza como TRR crónica se asocia a una reducción de la mortalidad de 30%-35% comparada con la hemodiálisis convencional. En el año 2014 se instrumentó esta técnica en el Hospital de Clínicas, siendo el centro pionero en el país en contar con ella como TRR crónico. El proceso de implementación implicó cambios de la infraestructura (monitores de diálisis, centro de tratamiento del agua), formación de recursos humanos, cambios en el funcionamiento y controles microbiológicos programados. El control de calidad sistemático y los diferentes estudios realizados en este período de cinco años han mostrado que es una técnica segura, capaz de remover solutos de tamaño medio y de disminuir los requerimientos de eritropoyetina. No se encuentra aún financiada por el sistema de salud, lo que puede constituir una barrera en su difusión a nivel nacional. En el presente trabajo se revisan las características fundamentales de la hemodiafiltración, su beneficio comparado con la hemodiálisis convencional, y el proceso de implementación de la técnica junto con algunos resultados iniciales en el Hospital de Clínicas.

Summary: Chronic kidney disease has an estimated prevalence of 6.5% to 8% in adults older than 18 years old in Uruguay. Despite efforts to make an early diagnosis and delay its progression, a percentage of patients require renal replacement therapy (RRT) with dialysis, the annual incidence rate being 166 patients per million population. Regardless of improvements in nephrology care and hemodialysis techniques, annual mortality ratex for this technique is high in our country (16.5%) and around the world. In order to improve these aspects, different dialysis techniques associating convection as a strategy to purify larger molecules that are rarely purified in conventional hemodialysis have been tried out. Online haemodiafiltration (OL-HDF) is a convective technique. When used as a chronic RRT it is associated to a 30-35% reduction in mortality compared to conventional hemodialysis. In 2014 this technique was introduced in the University Hospital, being it the first center that offered it as chronic renal replacement therapy. The implementation process implied changes in infrastructure (dialysis computer screens, water treatment center), the training of human resources, changes in the operation system and programmed microbiological controls. A systematic quality control and the different studies conducted in this 5-year period have proved it is a safe technique that removes average size solutes and reduces the erythropoietin requirements. This technique is still not funded by the health system, what may result in an obstacle for it to be applied nationally. This study reviews the main features of haemodiafiltration, its benefits when compared to conventional hemodialysis and the process needed to implement the technique, along with initial results in the University Hospital.

Resumo: No Uruguai a doença renal crônica tem uma prevalência estimada de 6.5 a 8% nos adultos maiores de 18 anos. Apesar dos esforços para realizar um diagnóstico precoce e retardar sua progressão uma porcentagem de pacientes requer terapia de substituição da função renal (TSFR) mediante diálise, com uma taxa de incidência anual de 166 pacientes/milhão de habitantes. Independentemente das melhorias na atenção nefrológica e nas técnicas de hemodiálise, a mortalidade anual dos pacientes em tratamento com esta técnica é elevada no Uruguai (16.5%) e no mundo todo. Buscando melhorar esses aspectos foram ensaiadas varias técnicas dialíticas que associam a convecção como estratégia para depurar moléculas de maior tamanho que habitualmente não são depuradas na hemodiálise convencional. A hemodiafiltração on line (HDF-OL) é uma técnica convectiva. Quando é utilizada como TSFR crônica está associada a uma redução da mortalidade de 30-35% comparada com a hemodiálise convencional. Esta técnica foi instrumentada em 2014 no Hospital de Clínicas, sendo este o centro pioneiro no Uruguai em utilizá-la como TSFR crônico. O processo de implementação impôs mudanças na infraestrutura (monitores de diálise, centro de tratamento da água), formação de Recursos Humanos e mudanças no funcionamento e controles microbiológicos programados. O controle de qualidade sistemático e os diferentes estudos realizados neste período de 5 anos mostraram que é uma técnica segura, capaz de remover solutos de tamanho médio e de reduzir os requerimentos de eritropoietina. A atual falta de financiamento pelo sistema de saúde pode ser uma barreira para sua difusão no país. Neste trabalho faz-se uma revisão das características fundamentais da hemodiafiltração, seu beneficio comparado com a hemodiálise convencional, o processo de implementação da técnica e alguns resultados iniciais do Hospital de Clínicas.

Removal of inorganic chemical species and organic matter from slaughterhouse wastewater via calcium acetate synthesized from eggshell.

The physicochemical treatment (PT) of slaughterhouse wastewater (SWW) was investigated. In the first stage, calcium acetate (Ca(Ac)2) was synthesized in five different ways: (1) acetic acid (HAc) and chicken eggshell (CaAc1), (2) lime (CaAc2), (3) a 1:1 eggshell and lime mixture (CaAc3), (4) a 1:2 eggshell and lime mixture (CaAc4), and (5) calcium oxide via the calcination of eggshell (CaAc5). The synthesized Ca(Ac)2 samples were characterized by IR, SEM, XRD, and EDS. Subsequently, the samples were used to precipitate oxyanions and organic matter. The experiments were carried out at pH 4 and 12. For the treatment with CaAc1 at pH 4, an acid (HCl, H2SO4, or HAc) was also added. The best results for CaAc1 in acid media were attained with HCl, where removal efficiencies of 82.23% total suspended solids, 76% turbidity, 81.43% color, 53.86% Fe, 69.74% Cu, and 14.64% Na were observed. This treatment also removed ∼99% fecal and total coliforms, 26.49% COD, and 78.39% TOC. The experiments were also performed at pH 12 using CaAc1. These afforded removal efficiencies of 92.7% turbidity, 84.7% color, 40.5% phosphates (PO43-), and 64.7% sulfates (SO42-). In addition, this method removed metals, 35.37% COD and 99% fecal and total coliforms.

Pre-treatment of soft drink wastewater with a calcium-modified zeolite to improve electrooxidation of organic matter.

Wastewater from soft drink manufacturing, having a high organic load (chemical oxygen demand (COD) = 4,500 mg L-1) and high alkalinity (2,653.7 mg L-1 CaCO3; pH 12), was pretreated with a calcium-modified zeolite to reduce the alkalinity and improve the electrooxidation of organic matter. The natural zeolite clinoptilolite was modified in various ways with Ca(OH)2 and CaCl2. The CaCl2-modified zeolite (ZSACaCl-72h) was more effective for the treatment of soft drink wastewater than the congener modified with Ca(OH)2, where the former reduced the alkalinity by 86% after 8 h. Electrooxidation of soft drink wastewater without zeolite pre-treatment was carried out with boron-doped diamond (BDD) electrodes under the optimal conditions (current intensity: 3 A; sample pH: 12), with 98% and 94.05% reduction of the COD and total organic carbon (TOC), respectively, after 14 h of treatment. Soft drink wastewater pretreated with calcium-modified clinoptilolite was also electrooxidized using the BDD system. The results showed that the pre-treatment was extremely convenient, reducing the treatment time to 6 h compared to the electrooxidation of wastewater. At a current intensity of 3 A, the treatment time was 8 h, with 100% reduction of colour and COD and 97.5% reduction of TOC.

Chemical activity relation of phosphorus and nitrogen presence in trace elements incorporation into underground water.

Anthropogenic activities can deteriorate the quality of groundwater destined for human use and consumption due to the fact that human activities cause changes in groundwater chemistry. The changes are induced by chemical species coming from industrial waste, which interacts with rocks and minerals. These trigger agents (phosphorus and nitrogen nutrients) which can incorporate trace elements (As, Fe, Mn, Pb, Cd, Ni, Zn). The main objective of the present work was to study the phosphate ions' and nitrogenous species' effects on the incorporation of trace elements into groundwater used for human consumption and to determine the physicochemical processes that participate in the incorporation of trace elements. The physicochemical analysis and elemental analysis by ICP of the groundwater that supplies the study area showed that the phosphorus (P) activity contributes in the incorporation of trace elements into the water. Significant correlations between the activities of P and Fe (0.516), Mn (0.553), Pb (0.756), and As (- 0.747) as well as the correlation of NH4+ with As indicate that the presence of chemical species such as PO43- (2.50-32.20 mg L-1), NO3- (0.89-30.80 mg L-1), and NH4+ (0.2-12.70 mg L-1) are triggering agents that favor the dissolution and mobility of As (0.014-0.020 mg L-1), Fe (0.020-1.14 mg L-1), Mn (0.007-0.254 mg L-1), Ni (0.002-0.0141 mg L-1), Zn (0.009-0.459 mg L-1), and Pb (0.009-0.0170 mg L-1), species with adverse health effects because they are considered carcinogenic. Adequate control of the nitrogenous and phosphated material prevents the dissolution and mobility of trace elements into the water.