Urbanization and industrialization are increasing extreme weather events, causing water quantity and quality reduction. Global water scarcity impacts 32.5 % of the urban population and is growing. ...Brazil has also witnessed water scarcity, notably in the southeast (2014–2015) and south (2019–2020), with reservoirs dropping below 20 % capacity. Water reuse is vital for mitigating scarcity, though it presents risks due to contaminants. Risk analysis studies are crucial for evaluating contamination sources, pathways, and exposure scenarios in water reuse practices. Various methodologies, including quantitative, semi-quantitative, and qualitative analyses, can be employed. Given the uncertainty and diverse factors, qualitative methods are recommended for non-potable water reuse risk analysis. This work presents a qualitative risk analysis methodology that allows to evaluate non-potable water reuse categories. It assesses factors affecting human health and the environment, considering exposure scenarios, characteristics of the receptors, and sources of reused water. The risk analysis of water reuse was carried out focusing on agricultural reuse, considering as alternatives the irrigation of soybean and sugarcane crops. By reviewing literature, the probability of occurrence and the magnitude of impact of the risk factors were identified and rated, using an increasing relative numeric scale. This process resulted in an overall risk value for comparing agricultural irrigation alternatives. The obtained results indicate a promising risk analysis model that can be adjusted and applied to various water reuse modalities and key factors. This adaptable risk analysis model is mainly related to water treatment methods, prompting the proposal of risk control measures.
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•The risk assessment methodology is applied for scenarios and non-potable water reuse.•Risks are evaluated, considering factors affecting human health and the environment.•Case studies of risk assessments are presented, focusing on agricultural use.•Adaptation to water reuse categories, sites, and controls are highlighted.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The stabilized sewage sludge, biosolid, has been widely investigated but despite numerous studies few ones have monitored the retention potential of metal ions of this material. This study aimed to ...investigate the zinc retention in biosolid-soil mixtures with different biosolid contents. The potential of zinc retention was evaluated using a physical model in a geotechnical centrifuge. The physical model was designed to represent a waste barrier of 3.75 m and to simulate a 1-year zinc percolation through the biosolid-soil layer. During the percolation, the zinc effluent was collected to monitoring its concentration over the time. Results show that the addition of 50% of biosolid in the soil, among other investigated proportions provided reductions up to 95% of the initial zinc concentration, considering a 300 days zinc percolation, while the natural soil, for the same period, provided reduction of 33%. The results clearly demonstrate that the incorporation of biosolid in the soil improved the zinc retention capacity. Chemical analysis suggested that the retention behavior of the biosolid is associated with the presence of organic matter and the pH value. The results are promising regarding the use of biosolid-soil mixtures in waste landfill barriers.
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It is increasingly important to find solutions for the problem of the aluminium anodising industry which generates a large amount of acid and alkaline wastewater, composed of high amounts of ...phosphates, sulphates, nitrates and aluminium. The sulphate removal trough ettringite precipitation is a simple process and involves a low-cost operating. The ettringite can be also formed during the cement hydration in soil-cement mixtures which causes several damages such as expansion. However, the effect of ettringite on the compressive strength, tensile strength and microstructure have few studies. This paper presents a novel experimental study on the influence of the industrial effluent treatment ettringite in resistance and microstructure of soil-cement mixtures. Experimental tests were performed using natural soil, soil mixed with 5% and 6% of cement and soil mixed with 5% and 6% of cement and ettringite for each material. The resistance of the materials was evaluated by unconfined compressive strength and indirect tensile strength, after 3, 7 and 14 days of cure. Additionally, several characterization tests and microstructure analysis were performed. Regarding the experimental results, the compressive strength and tensile strength decreases about 75% and 85%, respectively, when ettringite was added in soil-cement mixtures. The microstructure of natural soil, soil-cement and soil-cement-ettringite mixtures shows that the addition of cement and ettringite, simultaneously, increases the ettringite crystal formation mainly because the cement functions as a source of sulfate ions contributing with the formation of more crystals. Experimental results indicate that the incorporation of ettringite in soil-cement mixtures is not suitable for geotechnical applications.
Sulfate removal from waste chemicals by precipitation Benatti, Cláudia Telles; Tavares, Célia Regina Granhen; Lenzi, Ervim
Journal of environmental management,
2009, 2009-Jan, 2009-1-00, 20090101, Volume:
90, Issue:
1
Journal Article
Peer reviewed
Chemical oxidation using Fenton's reagent has proven to be a viable alternative to the oxidative destruction of organic pollutants in mixed waste chemicals, but the sulfate concentration in the ...treated liquor was still above the acceptable limits for effluent discharge. In this paper, the feasibility of sulfate removal from complex laboratory wastewaters using barium and calcium precipitation was investigated. The process was applied to different wastewater cases (two composite samples generated in different periods) in order to study the effect of the wastewater composition on the sulfate precipitation. The experiments were performed with raw and oxidized wastewater samples, and carried out according to the following steps: (1) evaluate the pH effect upon sulfate precipitation on raw wastewaters at pH range of 2–8; (2) conduct sulfate precipitation experiments on raw and oxidized wastewaters; and (3) characterize the precipitate yielded. At a concentration of 80
g
L
−1, barium precipitation achieved a sulfate removal up to 61.4% while calcium precipitation provided over 99% sulfate removal in raw and oxidized wastewaters and for both samples. Calcium precipitation was chosen to be performed after Fenton's oxidation; hence this process configuration favors the production of higher quality precipitates. The results showed that, when dried at 105
°C, the precipitate is composed of hemidrate and anhydrous calcium sulfate (∼99.8%) and trace metals (∼0.2%: Fe, Cr, Mn, Co, Ag, Mg, K, Na), what makes it suitable for reuse in innumerous processes.
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Establishing a treatment process for practical and economic disposal of laboratory wastewaters has become an urgent environmental concern of the Department of Chemical Engineering of the Universidade ...Estadual de Maringá (State University of Maringá), Brazil. Fenton and related reactions are potentially useful oxidation processes for destroying toxic organic compounds in water. In these reactions, hydrogen peroxide is combined with ferrous or ferric iron in the presence or absence of light to generate hydroxyl radicals (
OH). The feasibility of Fenton's reagent to treat waste chemicals from an academic research laboratory was investigated in this study. A response surface methodology was applied to optimize the Fenton oxidation process conditions using chemical oxygen demand (COD) removal as the target parameter to optimize, and the reagent concentrations, as related to the initial concentration of organic matter in the effluent, and pH as the control factors to be optimized. Maximal COD removal (92.3%) was achieved when wastewater samples were treated at pH 4 in the presence of hydrogen peroxide and iron in the ratios COD:H
2O
2=1:9 and H
2O
2:Fe
2+=4.5:1. Under these conditions, it was possible to obtain simultaneously maximal COD removal and minimal chemical sludge after treatment, which is a residue that needs further processing.
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As estações de tratamento de água (ETA’s) de ciclo completo realizam a potabilização das águas naturais por meio das etapas de coagulação, floculação, decantação, filtração, desinfecção, fluoretação ...e correção de pH. Para que haja a garantia do provimento de água tratada com boa qualidade, é necessário que seja avaliado o desempenho das etapas de tratamento de modo a assegurar a eficiência de cada uma delas. Pensando nisso, o presente trabalho visa avaliar o desempenho de uma ETA localizada no interior do Paraná por meio de indicadores fundamentados na qualidade da água bruta, coagulada, decantada, filtrada e tratada, nas características construtivas e operacionais das unidades de tratamento constituintes da ETA e no atendimento à norma técnica NBR 12216/92, às legislações Resolução CONAMA nº 357/5 e Portaria nº 888/21 e às considerações/recomendações realizadas pela literatura. Apesar da qualidade da água bruta mostrar-se comprometida, verificou-se que a qualidade da água tratada se encontra em conformidade com o padrão de potabilidade estabelecido pela Portaria nº888/21. Foram identificados, entretanto, aspectos construtivos e operacionais da ETA a serem melhorados. Devido a isso, o presente trabalho apresenta subsídios que visam melhorar a eficiência da ETA e possibilitar a sustentabilidade do seu sistema de tratamento de água.
Abstract The presence of nitrate in groundwater and surface water in concentrations above levels suitable for human consumption is an increasingly common problem. This is mainly due to human ...activity, such as the excessive use of fertilizers and the inadequate deactivation of pits. Water analysis laboratories very often carry out analyses to determine nitrate to control the presence of this anion in water intended for human consumption. One of the most commonly used methods is spectrophotometry, both with commercially available kits and by direct measurement of specific wavelengths. However, in these methods, the presence of organic matter and chloride can influence the results obtained. Thus, in this study, the applicability of the simplification (without acidification) of two methods for the determination of nitrate in water by ultraviolet–visible absorbance was verified in the presence of the above-mentioned interfering factors, and it was found that the absorbance method at 220 nm corrected for the absorbance at 275 nm, in its simplified form without acidification, can be used with concentrations of organic matter of 20 mg L−1 for high nitrate concentrations (10 mg L−1 NO3-N).
Fenton's process has proven to be a viable alternative for the oxidation of organic pollutants in mixed waste chemicals, with a high efficiency in the removal of heavy metals from the effluent as a ...side effect. However, a solid residue loaded with metals is obtained as a by-product. In this paper, the solids originating from the Fenton's oxidation of mixed waste chemicals from an academic laboratory were studied. The process was applied to different wastewater cases (two composite samples generated in different periods) in order to study the effect of their characteristics on the residues composition. Residues were evaluated and classified according to their leaching properties. In addition, a most comprehensive assessment of metal mobility in the residues was obtained by chemical speciation. The Fenton's residues were classified as hazardous according to Brazilian waste regulations. The application of the sequential dissolution procedure indicated that the metals in the Fenton's residues are mainly constituted of amorphous material (over 80%). Furthermore, the reactive fractions of the residues (exchangeable and amorphous iron oxide fractions) retain most of remaining metals. Therefore, the Fenton's residues present great potential for environmental contamination, and require an administration system and control of their final disposal.
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