RESUMEN
INTRODUCTION: Governmental measures aiming at social protection, with components of disease control, have potential positive impacts in the nutritional and health outcomes of the beneficiaries. The concomitant presence of these measures with environmental sanitation interventions may increase their positive effect. The context of simultaneous improvement of social protection and environmental sanitation is found in Brazil since 2007 and an assessment of the combined effects of both programs has not been performed so far. OBJECTIVE: To evaluate whether interaction effects between improvement of access to water, sanitation and solid waste collection with the Bolsa Família Program [PBF] were related to better responses in the reduction of morbidity due to diarrhea and malnutrition in children less than five years of age, acknowledging the positive results of these improved conditions and the PBF separately in coping with these diseases. METHODS: Descriptive and inferential analyses were performed through Generalized Linear Models of the Negative Binomial type of fixed effects, with and without addition of zeros. Interaction models were inserted in order to evaluate the outcomes when the two public policies of interest in the current study were present simultaneously in the municipalities. RESULTS: Interaction with negative effect when a concomitantly high municipal coverage of the Bolsa Família Program and adequate access to sanitation and solid waste collection were present. In contrast, regardless of municipal coverage by the PBF, the simultaneous presence of water and sanitation (0.028% / 0.019%); water and solid waste collection (0.033% / 0.014%); sanitation and solid waste collection (0.018% / 0.021%), all resulted in a positive effect, with a decrease in the average morbidity rates for both diseases. CONCLUSION: Investments aimed at universalizing water, sanitation and solid waste collection services should be priorities, aiming at reducing the incidence of morbidity due to malnutrition and diarrhea and preventing deaths from these poverty-related diseases.
Asunto(s)
Diarrea/epidemiología , Programas de Gobierno/economía , Desnutrición/epidemiología , Política Pública , Eliminación de Residuos/economía , Purificación del Agua/economía , Brasil/epidemiología , Preescolar , Ciudades/epidemiología , Femenino , Humanos , Incidencia , Lactante , Recién Nacido , Masculino , Morbilidad , Pobreza , UrbanizaciónRESUMEN
A cluster, randomized control trial was conducted to assess the effects of social marketing approach on purchase rates and water treatment behavior of Klorfasil, a chlorine-based household water treatment product among seven villages in Thomassique, Haiti, from May to December 2016. Villages were randomized to the free-trial (257 households) or cost-sharing (240 households) group. Households in the free-trial group were allowed 30 days of free Klorfasil use before purchase decision. Households who purchased Klorfasil were then followed up for 30, 60, and 180 days. At the last follow-up, respondents were asked if they would like to repurchase Klorfasil. Questionnaire survey and water quality assessment by residual-free chlorine were conducted in each survey. Chi-square test, t-test, and logistic regression were applied. The first purchase rate of the cost-sharing group was significantly higher than that of the free-trial group (79.2% versus 67.3%). By contrast, the repurchase rate of the free-trial group was higher (82.9% versus 66.3%). However, the overall repurchase rate was 71.6% and the proportion of long-term users was significantly higher in the cost-sharing group (56% versus 47%). Water treatment rates in the cost-sharing group were significantly higher than those in the free-trial group in the first and final surveys (odds ratio [OR] = 0.15, OR = 0.32). Households with high and medium economic status both had significantly higher purchase rates than low economic status households (OR = 4.40, OR = 1.94). Households with higher educated respondents had significantly better water treatment practices (OR = 2.15). The free-trial approach did not increase the first purchase rate but increased the repurchase rate later. The cost-sharing approach significantly encouraged long-term usage.
Asunto(s)
Composición Familiar , Población Rural , Purificación del Agua/economía , Purificación del Agua/métodos , Adolescente , Adulto , Recolección de Datos , Femenino , Haití , Halogenación , Humanos , Masculino , Persona de Mediana Edad , Encuestas y Cuestionarios , Adulto JovenRESUMEN
Water pollution by pesticides and other chemical contaminants is a subject of major importance due to the risk for human health and the environment. The search for remediation processes able to withdraw chemical contaminants from water and to allows water reuse is an urgent need. Herein, a simple and cheap system for pesticides removal was constructed and evaluated using water samples contaminated with two widely used herbicides (imazapic and imazethapyr, at g L-1 level). Operation parameters and process efficiency, in terms of removal rate in the reclaimed water and degradation rate of pesticides in the dry residue, were quantitatively determined. The model was tested in real-world field experiments and was able to remove more than 99.95% of both contaminants from a 10â¯L solution containing 4.16⯱â¯0.94â¯g of imazethapyr and 1.31⯱â¯0.17â¯g of imazapic, generating reusable water with minimum volume loss (<2.5%). Liquid chromatography coupled to mass spectrometry was used to determine the herbicides content in all samples and to estimate the degree of degradation of the substances as well as the occurrence of transformation products of imazapic and imazethapyr. The system efficiency in removing contaminants of emerging concern from surface water was also evaluated. The process have generated output water with undetected levels for two fungicides present in a local river in Southern Brazil.
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Plaguicidas/aislamiento & purificación , Contaminantes Químicos del Agua/aislamiento & purificación , Purificación del Agua/instrumentación , Brasil , Cromatografía Liquida/métodos , Imidazoles/aislamiento & purificación , Espectrometría de Masas/métodos , Ácidos Nicotínicos/aislamiento & purificación , Ríos/química , Contaminantes Químicos del Agua/análisis , Purificación del Agua/economía , Purificación del Agua/métodosRESUMEN
Watershed studies that account for nutrient loadings are crucial for suitable river basin and estuarine management. This study aims to contribute to the environmental planning and decision making regarding nitrogen and phosphorus loadings for the watershed of the Vitória Bay Estuarine System (VBES; 1925 km2) in southeast Brazil. Here, we estimate that the VBES had annual loadings (in 2016) from ten tributary river basins of 5480 and 10,784 t for P and N, respectively, based on emission factors for natural and anthropogenic sources. The main contribution sources were related to livestock farming (4801 t of P and 8000 t of N) and domestic wastewater (492 t of P and 1706 t of N). However, urban loadings have higher expressions when considering the input by watershed area (0.25 and 0.87 t km-2 year-1 of P and N yields, respectively), which are mainly due to wastewater since 70% of the sewage is untreated. Urban emissions play a prominent role and have a tendency to be aggravated due to Brazilian population growth (0.8% annual rate). If the current wastewater emissions continue, P and N loadings will likely increase by 1.316% to totals of 713 and 2474 t year-1 in 2050 for P and N, respectively. Considering that the wastewater tertiary treatment cost is US$ 0.50 m-3, and that in the future 70% of all wastewater will be collected, the P and N loadings will drop to 18.4 and 424.1 t year-1, respectively, with a treatment cost of 25 million USD year-1. The model holds well for non-regulated watersheds. However, for regulated basins, such as the Santa Maria de Vitória, the model overestimates the loadings mainly due to the damming systems in these watersheds (accounting for 49% retention of P and 0.13% retention of N).
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Monitoreo del Ambiente , Nitrógeno/análisis , Fósforo/análisis , Ríos/química , Aguas del Alcantarillado/química , Suelo/química , Animales , Brasil , Ganado , Modelos Teóricos , Tecnología de Sensores Remotos , Purificación del Agua/economíaRESUMEN
In the context of a regional Chilean project (FIC Taltape project, BIP code 30158422-0), a multi-effect distillation (MED) pilot plant has been built and installed in a small community in the north of Chile (Taltape, Arica) in order to supply treated water for agricultural and domestic purposes. The aim of this paper is to assess the techno-economic feasibility of this system for supplying water with the required quality to the population. The characterization of the feed water and the effluents from the MED pilot plant (distillate and brine), obtained during five months of operation, has been firstly performed. Then, the prediction of the operation of the water treatment system with solar energy has been carried out using a typical meteorological year and the design of a static solar field that cover the thermal energy needs of the water treatment plant. The annual simulations of the MED pilot plant operating with solar energy showed that the water needs can be mostly covered using a static solar thermal field with a total area of 113.2â¯m2, which would generate roughly 46% of the total heat required by the water treatment plant. The technical analysis has been completed with an exhaustive economic assessment. The specific water costs have been determined for the MED pilot plant and the scale factor when the productivity is increased up to 5000â¯m3/day has been evaluated. The cost of distillated water produced by the MED plant varied from 15.0â¯USD$/m3 for the 10â¯m3/day production capacity to 1.25â¯USD$/m3 when this variable is increased to 5000â¯m3/day.
Asunto(s)
Riego Agrícola/métodos , Purificación del Agua/métodos , Riego Agrícola/economía , Chile , Destilación , Agua , Purificación del Agua/economía , Abastecimiento de AguaRESUMEN
The water industry presents several structures in different countries and also within countries. Hence, several studies have been conducted to evaluate the presence of economies of scope and scale in the water industry leading to inconclusive results. The lack of a common methodology has been identified as an important factor contributing to divergent conclusions. This paper evaluates, for the first time, the presence of economies of scale and scope in the water industry using a flexible technology approach integrating operational and exogenous variables of the water companies in the cost functions. The empirical application carried out for the English and Welsh water industry evidenced that the inclusion of exogenous variables accounts for significant differences in economies of scale and scope. Moreover, completely different results were obtained when the economies of scale and scope were estimated using common and flexible technology methodological approaches. The findings of this study reveal the importance of using an appropriate methodology to support policy decision-making processes to promote sustainable urban water activities.
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Industrias/economía , Tecnología/economía , Purificación del Agua/economía , Abastecimiento de Agua/economía , Inglaterra , GalesRESUMEN
A novel arrangement for an electro-Fenton reactor aimed to treat neutral wastewater is presented. The arrangement consists on three-compartments in series, two of them packed with a cation exchange resin and one positioned between these, containing a polarized activated carbon column where the electrochemical generation of the Fenton reagent takes place. While the hydroxyl radicals electrochemically produced in-situ, react with the pollutant species adsorbed on the activated carbon cathode, the resin compartments administrate and collect the iron cation and the hydrated proton species in alternating flow direction cycles. The resulting process is a system that does not require acid or iron chemical addition to the process while at the same time, renders decontaminated water free of iron-dissolved species at neutral pH. The proposed electrochemical reactor arrangement is therefore the basis for the design of commercially viable electro-Fenton reactors in which the addition and subsequent removal of acid and iron chemicals is avoided; two of the currently most limiting features for the development of electro-Fenton technology for treating wastewater.
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Técnicas Electroquímicas/métodos , Peróxido de Hidrógeno/química , Hierro/química , Aguas Residuales/química , Contaminantes Químicos del Agua/análisis , Purificación del Agua/métodos , Análisis Costo-Beneficio , Técnicas Electroquímicas/economía , Electrodos , Radical Hidroxilo/química , Oxidación-Reducción , Purificación del Agua/economíaRESUMEN
Low adoption and compliance levels for household water treatment and safe storage (HWTS) technologies have made it challenging for these systems to achieve measurable health benefits in the developing world. User compliance remains an inconsistently defined and poorly understood feature of HWTS programs. In this article, we develop a comprehensive approach to understanding HWTS compliance. First, our Safe Drinking Water Compliance Framework disaggregates and measures the components of compliance from initial adoption of the HWTS to exclusive consumption of treated water. We apply this framework to an ultraviolet (UV)-based safe water system in a cluster-randomized controlled trial in rural Mexico. Second, we evaluate a no-frills (or "Basic") variant of the program as well as an improved (or "Enhanced") variant, to test if subtle changes in the user interface of HWTS programs could improve compliance. Finally, we perform a full-cost analysis of both variants to assess their cost effectiveness (CE) in achieving compliance. We define "compliance" strictly as the habit of consuming safe water. We find that compliance was significantly higher in the groups where the UV program variants were rolled out than in the control groups. The Enhanced variant performed better immediately postintervention than the Basic, but compliance (and thus CE) degraded with time such that no effective difference remained between the two versions of the program.
Asunto(s)
Desinfección/métodos , Agua Potable/análisis , Conocimientos, Actitudes y Práctica en Salud , Purificación del Agua/métodos , Análisis Costo-Beneficio , Desinfección/economía , Desinfección/instrumentación , Composición Familiar , Humanos , México , Población Rural , Rayos Ultravioleta , Microbiología del Agua , Purificación del Agua/economía , Purificación del Agua/instrumentación , Abastecimiento de Agua/economía , Abastecimiento de Agua/métodosRESUMEN
Household water treatment can reduce diarrheal morbidity and mortality in developing countries, but adoption remains low and supply is often unreliable. To test effects of marketing strategies on consumers and suppliers, we randomized 1,798 households in rural Haiti and collected data on purchases of a household chlorination product for 4 months. Households received randomly selected prices ($0.11-$0.56 per chlorine bottle), and half received monthly visits from sales agents. Each $0.22 drop in price increased purchases by 0.10 bottles per household per month (P < 0.001). At the mean price, each 1% drop in price increased purchases by 0.45% (elasticity = 0.45). There is suggestive evidence that household visits by some sales agents increased purchases at mid-range prices; however, the additional revenue did not offset visit cost. Choosing the lowest price and conducting visits maximizes chlorine purchase, whereas slightly raising the retail price and not conducting visits maximizes cost recovery. For the equivalent cost, price discounts increase purchases 4.2 times as much as adding visits at the current retail price. In this context, price subsidies may be a more cost-effective use of resources than household visits, though all marketing strategies tested offer cost-effective ways to achieve incremental health impact. Decisions about pricing and promotion for health products in developing countries affect health impact, cost recovery, and cost-effectiveness, and tradeoffs between these goals should be made explicit in program design.
Asunto(s)
Cloro , Desinfectantes , Agua Potable/normas , Purificación del Agua/economía , Purificación del Agua/métodos , Análisis Costo-Beneficio , Composición Familiar , Haití , Humanos , Población Rural , Calidad del AguaRESUMEN
The biotechnology sector is continually seeking sustainable and more economical bioprocesses. Fermentation media produced with cheap components or wastes reduce production costs. Moreover, if wastes are used, they contribute to avoid environmental pollution. In this work, microbial growth media based on molasses or acidified glycerol as carbon sources and fertilizer as nitrogen source were tested for the production of a whole-cell catalyst that could be used in Cr(VI)-containing wastewater treatments. Results showed that the highest biomass production yield was obtained with a medium containing acidified glycerol 5% v/v and fertilizer 0.6% v/v. The biomass produced using this medium was immobilized in calcium alginate beads and used as catalyst in the biotransformation of Cr(VI) into Cr(III). The catalyst could be efficiently used for 5 reduction cycles of 40 mg/l Cr(VI) each. Cr(III) retention assays were performed to determine whether Cr(III) could be retained by the catalyst avoiding its solubilization in the supernatants. The retention capacity of the catalyst at 32 °C and pH 3.0 was 3 mg Cr(III)/g. Both an alternative and economical fermentation medium is here proposed for the optimization of Cr(VI)-containing wastewater treatment.
El sector industrial biotecnológico continuamente busca bioprocesos más económicos y sustentables. El uso de medios de cultivo producidos con componentes de bajo costo o con residuos reduce el presupuesto global del proceso y, particularmente si se utilizan residuos, se contribuye, además, a evitar la contaminación ambiental. En este trabajo se probaron medios de cultivo basados en melaza de caña o glicerol ácido como fuentes de carbono y energía, y fertilizante como fuente de nitrógeno, para la producción de un biocatalizador que podría ser usado para el tratamiento de aguas residuales que contienen Cr(VI). Los resultados mostraron que el mayor rendimiento de producción de biomasa se obtuvo con un medio que contenía 5% v/v de glicerol ácido y 0,6% v/v de fertilizante. Utilizando este medio se produjo la biomasa suficiente para la biotransformación de Cr(VI) a Cr(III), luego de ser inmovilizada en alginato de calcio. El proceso pudo ser aplicado eficientemente durante 5 ciclos de reducción de 40 mg/l de Cr(VI) cada uno. Además, se realizaron ensayos de retención de Cr(III) para determinar si esta especie química podría ser removida de la solución por interacción con el biocatalizador. La capacidad de retención obtenida por el biocatalizador a 32 °C y pH 3 fue de 3 mg de Cr(III)/g. De esta manera, se propone un medio de cultivo alternativo y económico para la efectivización de un tratamiento de aguas residuales que contengan Cr(VI).
Asunto(s)
Biotransformación , Purificación del Agua/métodos , Tecnología de Bajo Costo/economía , Biocatálisis , Aguas Residuales/microbiología , Cromo/análisis , Purificación del Agua/economíaRESUMEN
The biotechnology sector is continually seeking sustainable and more economical bioprocesses. Fermentation media produced with cheap components or wastes reduce production costs. Moreover, if wastes are used, they contribute to avoid environmental pollution. In this work, microbial growth media based on molasses or acidified glycerol as carbon sources and fertilizer as nitrogen source were tested for the production of a whole-cell catalyst that could be used in Cr(VI)-containing wastewater treatments. Results showed that the highest biomass production yield was obtained with a medium containing acidified glycerol 5% v/v and fertilizer 0.6% v/v. The biomass produced using this medium was immobilized in calcium alginate beads and used as catalyst in the biotransformation of Cr(VI) into Cr(III). The catalyst could be efficiently used for 5 reduction cycles of 40mg/l Cr(VI) each. Cr(III) retention assays were performed to determine whether Cr(III) could be retained by the catalyst avoiding its solubilization in the supernatants. The retention capacity of the catalyst at 32°C and pH 3.0 was 3mg Cr(III)/g. Both an alternative and economical fermentation medium is here proposed for the optimization of Cr(VI)-containing wastewater treatment.
Asunto(s)
Biodegradación Ambiental , Cromo/metabolismo , Medios de Cultivo , Fermentación , Pseudomonas/efectos de los fármacos , Aguas Residuales/química , Contaminantes Químicos del Agua/metabolismo , Purificación del Agua/métodos , Biomasa , Carbono/metabolismo , Catálisis , Células Inmovilizadas , Cromo/análisis , Medios de Cultivo/economía , Medios de Cultivo/farmacología , Fertilizantes , Glicerol/economía , Glicerol/farmacología , Indicadores y Reactivos/economía , Melaza , Nitrógeno/metabolismo , Pseudomonas/crecimiento & desarrollo , Pseudomonas/metabolismo , Solubilidad , Aguas Residuales/economía , Contaminantes Químicos del Agua/análisis , Purificación del Agua/economíaRESUMEN
The objective of this study was to examine the ability of a solid waste produced during beneficiation of ornamental rocks to remove mercury (Hg) from an industrial effluent and aqueous solutions under various conditions. Batch studies have been carried out by observing the effects of pH, concentration of the adsorbate, contact time, and so on. Various sorption isotherm models such as Langmuir, Freundlich, and Tóth have been applied for the adsorbent. Film and intraparticle diffusion were both found to be rate-limiting steps. Adsorption was properly described by the Freundlich model (capacity constant of 0.3090 (mg g(-1))(mg L(-1))(-1/n) and adsorption intensity indicator of 2.2939), which indicated a favorable sorption and encouraged subsequent studies for treatment of Hg-containing industrial effluent. Industrial effluent treatment efficiency reached Hg removals greater than 90% by using ornamental rock solid waste (ORSW). Besides, desorption studies indicated that the maximum recovery of mercury was 100 ± 2% for 1 mol L(-1) HNO3 and 74 ± 8% for 0.1 mol L(-1) HNO3. The ORSW could be reused thrice without significant difference on the Hg removal rate from industrial effluent. These findings place ORSW as a promising efficient and low-cost adsorbent for the removal of Hg from aqueous solutions and industrial effluent.
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Residuos Industriales , Mercurio/aislamiento & purificación , Aguas Residuales , Contaminantes Químicos del Agua/aislamiento & purificación , Purificación del Agua/métodos , Adsorción , Brasil , Análisis Costo-Beneficio , Concentración de Iones de Hidrógeno , Residuos Industriales/análisis , Temperatura , Aguas Residuales/análisis , Purificación del Agua/economíaRESUMEN
Several studies have reported the adverse effects of recalcitrant compounds and emerging contaminants present in industrial effluents, which are not degradable by ordinary biological treatment. Many of these compounds are likely to accumulate in living organisms through the lipid layer. At concentrations above the limits of biological tolerance, these compounds can be harmful to the ecosystem and may even reach humans through food chain biomagnification. In this regard, advanced oxidation processes (AOPs) represent an effective alternative for the removal of the pollutants. This study focused on the AOP involving the use of ultraviolet radiation in homogeneous and heterogeneous systems. Based on the literature review, comparisons between natural and artificial light were established, approaching photoreactors constructive and operational characteristics. We concluded that the high availability of solar power in Brazil would make the implementation of the AOP using natural solar radiation for the decontamination of effluents feasible, thereby contributing to clean production and biodiversity conservation. This will serve as an important tool for the enforcement of environmental responsibility among public and private institutions.
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Energía Solar , Purificación del Agua/métodos , Brasil , Oxidación-Reducción , Luz Solar , Rayos Ultravioleta , Aguas Residuales , Purificación del Agua/economíaRESUMEN
A modified version of the QuEChERS method has been evaluated for the determination of 21 pharmaceuticals and 6 personal care products (PPCPs) in drinking-water sludge samples by employing ultra high liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The performance of the method was evaluated through linearity, recovery, precision (intra-day), method detection and quantification limits (MDL and MQL) and matrix effect. The calibration curves prepared in acetonitrile and in the matrix extract showed a correlation coefficient ranging from 0.98 to 0.99. MQLs values were on the ng g(-1) order of magnitude for most compounds. Recoveries between 50% and 93% were reached with RSDs lower than 10% for most compounds. Matrix effect was almost absent with values lower than 16% for 93% of the compounds. By coupling a quick and simple extraction called QuEChERS with the UPLC-MS/MS analysis, a method that is both selective and sensitive was obtained. This methodology was successfully applied to real samples and caffeine and benzophenone-3 were detected in ng g(-1) levels.
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Fraccionamiento Químico/métodos , Cosméticos/aislamiento & purificación , Agua Potable/química , Preparaciones Farmacéuticas/aislamiento & purificación , Seguridad , Aguas del Alcantarillado/química , Purificación del Agua/métodos , Cromatografía Líquida de Alta Presión , Cosméticos/análisis , Preparaciones Farmacéuticas/análisis , Espectrometría de Masa por Ionización de Electrospray , Espectrometría de Masas en Tándem , Contaminantes Químicos del Agua/análisis , Contaminantes Químicos del Agua/aislamiento & purificación , Purificación del Agua/economíaRESUMEN
The so-called social technologies have been widely used in many places around the world as a viable alternative for low-income populations to gain access to opportunities for employment and income and other aspects related to quality of life, including basic sanitation. This paper conducts a cost-benefit analysis of using a low cost technology for drinking water used in several countries, namely the SODIS system. The study was conducted in riverside communities living in the island area of Belem municipality, located in the Brazilian Amazon. Data were collected through questionnaires answered by families living on three islands: Jutuba, Nova and Urubuoca. The results were positive, considering the cost-benefit analysis of the project, which demonstrates the economic viability of using the SODIS system in the situation investigated.
Asunto(s)
Promoción de la Salud/economía , Promoción de la Salud/métodos , Purificación del Agua/economía , Purificación del Agua/métodos , Abastecimiento de Agua/economía , Abastecimiento de Agua/normas , Brasil , Análisis Costo-Beneficio , Desinfección , Humanos , Características de la Residencia , SociologíaRESUMEN
As chamadas tecnologias sociais vêm sendo largamente usadas em muitos lugares do mundo como alternativa viável para que populações de baixa renda tenham acesso a oportunidades de ocupação e renda e outros aspectos relacionados à qualidade de vida, inclusive o saneamento básico. O presente trabalho realiza uma avaliação custo-benefício do uso de uma tecnologia de baixo custo para abastecimento de água potável utilizada em vários países, o sistema SODIS. O estudo foi realizado em comunidades ribeirinhas que vivem na área insular do município de Belém (PA), localizado na Amazônia brasileira. Os dados foram obtidos por meio de questionários respondidos por famílias moradoras de três ilhas: Jutuba, Nova e Urubuoca. Os resultados mostraram-se positivos, considerando a análise de custo-benefício do projeto, o que comprova a viabilidade econômica do uso do sistema SODIS na situação investigada.
The so-called social technologies have been widely used in many places around the world as a viable alternative for low-income populations to gain access to opportunities for employment and income and other aspects related to quality of life, including basic sanitation. This paper conducts a cost-benefit analysis of using a low cost technology for drinking water used in several countries, namely the SODIS system. The study was conducted in riverside communities living in the island area of Belem municipality, located in the Brazilian Amazon. Data were collected through questionnaires answered by families living on three islands: Jutuba, Nova and Urubuoca. The results were positive, considering the cost-benefit analysis of the project, which demonstrates the economic viability of using the SODIS system in the situation investigated.
Asunto(s)
Humanos , Promoción de la Salud/economía , Promoción de la Salud/métodos , Purificación del Agua/economía , Purificación del Agua/métodos , Abastecimiento de Agua/economía , Abastecimiento de Agua/normas , Brasil , Análisis Costo-Beneficio , Desinfección , Características de la Residencia , SociologíaRESUMEN
Excess greenhouse gas emissions and the concomitant effect on global warming have become significant environmental, social and economic threats. In this context, the development of renewable, carbon-neutral and economically feasible biofuels is a driving force for innovation worldwide. A lot of effort has been put into developing biodiesel from microalgae. However, there are still a number of technological, market and policy barriers that are serious obstacles to the economic feasibility and competitiveness of such biofuels. Conversely, there are also a number of business opportunities if the production of such alternative biofuel becomes part of a larger integrated system following the Biorefinery strategy. In this case, other biofuels and chemical products of high added value are produced, contributing to an overall enhancement of the economic viability of the whole integrated system. Additionally, dual purpose microalgae-bacteria-based systems for treating wastewater and production of biofuels and chemical products significantly contribute to a substantial saving in the overall cost of microalgae biomass production. These types of systems could help to improve the competitiveness of biodiesel production from microalgae, according to some recent Life Cycle Analysis studies. Furthermore, they do not compete for fresh water resources for agricultural purposes and add value to treating the wastewater itself. This work reviews the most recent and relevant information about these types of dual purpose systems. Several aspects related to the treatment of municipal and animal wastewater with simultaneous recovery of microalgae with potential for biodiesel production are discussed. The use of pre-treated waste or anaerobic effluents from digested waste as nutrient additives for weak wastewater is reviewed. Isolation and screening of microalgae/cyanobacteria or their consortia from various wastewater streams, and studies related to population dynamics in mixed cultures, are highlighted as very relevant fields of research. The species selection may depend on various factors, such as the biomass and lipid productivity of each strain, the characteristics of the wastewater, the original habitat of the strain and the climatic conditions in the treatment plant, among others. Some alternative technologies aimed at harvesting biomass at a low cost, such as cell immobilization, biofilm formation, flocculation and bio-flocculation, are also reviewed. Finally, a Biorefinery design is presented that integrates the treatment of municipal wastewater with the recovery of oleaginous microalgae, together with the use of seawater supplemented with anaerobically digested piggery waste for cultivating Arthrospira (Spirulina) and producing biogas, biodiesel, hydrogen and other high added value products. Such strategies offer new opportunities for the cost-effective and competitive production of biofuels along with valuable non-fuel products.
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Bacterias/metabolismo , Biocombustibles/microbiología , Reactores Biológicos/microbiología , Microalgas/metabolismo , Aguas Residuales/microbiología , Purificación del Agua/métodos , Animales , Microalgas/crecimiento & desarrollo , Aguas Residuales/economía , Purificación del Agua/economíaRESUMEN
An electro-coagulation laboratory scale system using aluminium plates electrodes was studied for the removal of organic and inorganic pollutants as a by-product from leather finishing industrial process. A fractional factorial 2(3) experimental design was applied in order to obtain optimal values of the system state variables. The electro-coagulation (EC) process efficiency was based on the chemical oxygen demand (COD), turbidity, total suspended solid, total fixed solid, total volatile solid, and chemical element concentration values. Analysis of variance (ANOVA) for final pH, total fixed solid (TFS), turbidity and Ca concentration have confirmed the predicted models by the experimental design within a 95% confidence level. The reactor working conditions close to real effluent pH (7.6) and electrolysis time in the range 30-45 min were enough to achieve the cost effective reduction factors of organic and inorganic pollutants' concentrations. An appreciable improvement in COD removal efficiency was obtained for electro-coagulation treatment. Finally, the technical-economical analysis results have clearly shown that the electro-coagulation method is very promising for industrial application.
Asunto(s)
Aluminio/química , Técnicas Electroquímicas/métodos , Curtiembre , Eliminación de Residuos Líquidos/métodos , Purificación del Agua/métodos , Análisis de Varianza , Calcio/análisis , Costos y Análisis de Costo , Electricidad , Técnicas Electroquímicas/economía , Electrodos , Electrólisis , Concentración de Iones de Hidrógeno , Hierro/química , Cinética , Nefelometría y Turbidimetría , Factores de Tiempo , Compuestos Orgánicos Volátiles/análisis , Eliminación de Residuos Líquidos/economía , Contaminantes Químicos del Agua/aislamiento & purificación , Purificación del Agua/economíaRESUMEN
A major challenge in developing countries concerning domestic wastewaters is to decrease their treatment costs. In the present study, a new cost-effective reactor called gradual concentric chambers (GCC) was designed and evaluated at lab-scale. The effluent quality of the GCC reactor was compared with that of an upflow anaerobic sludge bed (UASB) reactor. Both reactors showed organic matter removal efficiencies of 90 percent; however, the elimination of nitrogen was higher in the GCC reactor. The amount of biogas recovered in the GCC and the UASB systems was 50 percent and 75 percent of the theoretical amount expected, respectively, and both reactors showed a slightly higher methane production when the feed was supplemented with an additive based on vitamins and minerals. Overall, the economical analysis, the simplicity of design and the performance results revealed that the GCC technology can be of particular interest for sewage treatment in developing countries.
Asunto(s)
Coliformes/análisis , Coliformes/prevención & control , Purificación del Agua/economía , Purificación del Agua/métodos , Reactores Biológicos , Biocombustibles/métodos , Cámaras/métodos , Costos y Análisis de Costo/economía , Costos y Análisis de Costo/métodos , Países en Desarrollo/economíaRESUMEN
Mercury (Hg) is one of the most toxic heavy metals commonly found in the global environment. Its toxicity is related to the capacity of its compounds to bioconcentrate in organisms and to biomagnify through food chain. A wide range of adsorbents has been used for removing Hg(II) from contaminated water. Chitosan is obtained by alkaline deacetylation of chitin. The adsorption capacity of chitosan depends on the origin of the polysaccharide, and on the experimental conditions in the preparation, that determine the degree of deacetylation. A great number of chitosan derivatives have been obtained by crosslinking with glutaraldehyde or epichlorohydrin among others or by grafting new functional groups on the chitosan backbone with the aim of adsorbing Hg(II). The new functional groups are incorporated to change the pH range for Hg(II) sorption and/or to change the sorption sites in order to increase sorption selectivity. The chemical modification affords a wide range of derivatives with modified properties for specific applications. Hg(II) adsorption on chitosan or chitosan derivatives is now assumed to occur through several single or mixed interactions: chelation or coordination on amino groups in a pendant fashion or in combination with vicinal hydroxyl groups, electrostatic attraction in acidic media or ion exchange with protonated amino groups. This review reports the recent developments in the Hg(II) removal in waste water treatment, using chitosan and its derivatives in order to provide useful information about the different technologies. When possibly the adsorption capacity of chitosan and chitosan derivatives under different experimental conditions is reported to help to compare the efficacy of the Hg(II) removal process. A comparison with the adsorption capacity of other low-cost adsorbents is also tabled.