Performance of a coagulation–ultrafiltration hybrid process for water supply treatment

AbstractThe combination of coagulation/flocculation and ultrafiltration in the process of drinking water treatment was investigated using natural (chitosan) and chemical (aluminum sulfate) coagulants. A 0.1μm single-channel membrane was applied at pressures of 1bar and 2bar, using the principle of crossflow filtration. The final produced water quality was assessed considering the efficiency of removal of color, turbidity, COD, and compounds that absorb UV at 254nm, among other physico-chemical and microbiological parameters. The coagulation/flocculation with chitosan as coagulant (CFQ) was efficient in removing compounds that add color and turbidity and that absorb UV at 254nm, with levels that were very similar to those obtained with the coagulation/flocculation process with aluminum sulfate as coagulant (CFS). Performance evaluation of the hybrid systems (CFS-UF and CFQ-UF) showed that the permeate quality was increased when compared with individually operated systems (UF, CFS, and CFQ). The CFQ-UF process caused higher membrane fouling (79% at 2bar), but yielded a higher stabilized permeate flux, which was approximately twice that achieved with CFS-UF. Based on the results, one can say that chitosan has a potential application as natural coagulant in CF-UF hybrid processes for treating drinking water with relatively high turbidity

Biosorption of the Copper and Cadmium Ions - a Study through Adsorption Isotherms Analysis

In this work, the biosorption process of copper-cadmium ions binary mixture by using marine algae Sargassum filipendula was investigated. A set of experiments was performed to obtain equilibrium data for the given batch operational conditions - T=30°C, pH=5. The interpretation of equilibrium data was based on the binary adsorption isotherms models in the Langmuir and Freundlich forms. To evaluate the models parameters, nonlinear identification procedure was used based on the Least Square statistical method and SIMPLEX local optimizer. An analysis of the obtained results showed that the marine algae biomass has higher affinity to copper ions than to cadmium ones. The biomass maximum adsorption capacity for the binary system was about 1.16 meq/g

Diagnóstico de uma usina de asfalto visando a implantação de um Sistema de Gestão Ambiental com base na norma ABNT NBR ISO 14001

Currently, organizations are beginning to worry about the environmental impacts they create, because it found that over the years the cost of prevention is lower than the recovery from accidents, or environmental, technological or occupational. The aim of this study was to perform an environmental diagnosis of the Asphalt Plant, with the aim of proposing an Environmental Management System, following the rules of Brazilian ABNT NBR ISO 14001. The methodology involved the application of questionnaires to the staff and a program of visits to the company to observe the production process, the environmental survey, identification and assessment of environmental impacts and possible response to current environmental legislation. Based on the results, it was done several recommendations, among them, it was suggested that the company will need to introduce an environmental management system (EMS), which will require the commitment of the organization towards the environmental management and the creation of a specific sector of environment. This sector will be able to propose and implement solutions to environmental issues identified. Key words: EMS, environmental impact, asphalt plant.Atualmente, as organizações começam a se preocupar com impactos ambientais que geram, pois está constatado que ao longo dos anos o custo da prevenção é menor do que o da recuperação de acidentes, seja de ordem ambiental, tecnológico ou ocupacional. O objetivo principal deste trabalho foi realizar um diagnóstico ambiental de uma Usina de Asfalto, com a finalidade de propor um Sistema de Gestão Ambiental, seguindo as normas brasileiras ABNT NBR ISO 14001. A metodologia utilizada envolveu a aplicação de questionários aos funcionários e um programa de visitas à empresa para observação do processo produtivo, levantamento de aspectos ambientais, identificação e avaliação dos possíveis impactos ambientais e atendimento a legislação ambiental vigente. Com base nos resultados obtidos foram feitas algumas recomendações, entre elas, sugeriu-se a empresa que para a implantação de um Sistema de Gestão Ambiental (SGA), será necessário o compromisso da organização frente ao gerenciamento ambiental e à criação de um setor específico de meio ambiente, que possa propor e implantar soluções para os aspectos ambientais identificados. Palavras chaves: SGA, impacto ambiental, usina de asfalto

Modelling of the pH effect on the biosorption of heavy metals by marine algae Sargassum filipendula

Modelling of the pH effect on the biosorption of heavy metals by marine algae Sargassum filipendula. In this paper the biosorption of metal ions Cu(2+), Cd(2+) and Zn(2+) in single-component system by Sargassum filipendula pre-treated with 0.5 M CaCl(2) was studied. The experiments were carried out in a batch reactor at different fixed pH (3.0, 4.0, 5.0 and 6.0) and 30 degrees C. All the equilibrium data obtained were described using two pH-dependent isotherm models, based on the Langmuir isotherm. Artificial neural networks was also used to represent the pH effect on the biosorption equilibrium. The input of the networks were the equilibrium concentration of the metal in the fluid phase and the pH. As output the concentration of the metallic specie in the biosorbent was used. The results showed that the modeling using artificial neural networks technique represented the equilibrium data much better than the conventional modeling by the pH-dependent isotherm models.33443944

Biossorção de cromo(III) em coluna de leito fixo

The chromium (III) uptake on pre-treated seaweed Sargassum filipendula biomass was investigated in fixed bed. In the experiments 8 g of the biosorbent of 2.6 mm diameter medium were deposited in the column. The operation conditions were: feed solution pH of 3, temperature of 30ºC, flow rate of 6 mL.min-1 and feed concentrations of chromium of 0.95, 1.45, 1.99, 2.82, 4.79 and 5.78 meq.L-1. The experimental equilibrium data in the column and batch systems have been analyzed using the irreversible isotherm (qmax = 1.93 meq.g-1) and the Langmuir isotherm, respectively, for simulate the sorption of chromium ion. The rupture curves obtained experimentally were modeled mathematically using a model that considers the mass transfer in the solid phase as the controlling step. The mass transfer in the solid (K) was influenced by the initial chromium concentration in the studied range. Key words: biosorption, chromium, bed fixed.A remoção de cromo (III) empregando a biomassa da alga marinha pré-tratada Sargassum filipendula foi investigada em coluna de leito fixo. Nos experimentos realizados cerca de 8 g do biossorvente de diâmetro médio 2,6 mm foram depositados na coluna. As condições de operação foram: pH da solução de alimentação de 3,0, temperatura de 30ºC, vazão de 6 mL.min-1 e concentrações de alimentação de cromo de 0,95, 1,45, 1,99, 2,82, 4,79 e 5,78 meq.L-1. Os dados experimentais de equilíbrio obtidos foram ajustados empregando o modelo da isoterma irreversível (qmax= 1,93 meq.g-1) e o modelo de Langmuir obtido em sistema batelada foram utilizados para simular a biossorção do íon cromo. As curvas de ruptura obtidas experimentalmente foram modeladas matematicamente empregando-se um modelo que considera a transferência de massa na fase sólida como etapa controladora do processo. A transferência de massa no sólido (K) foi influenciada pela concentração inicial do cromo na faixa estudada. Palavras-chave: biossorção, cromo, leito fixo

Efeito da vazão volumétrica nas curvas de ruptura para o sistema de biossorção de Cr (III) e Ni (II)

In a fixed bed, sorption behavior is based on the mass transfer zones (MTZ). For a given operational flow rate, in which the column yields breakthrough curves close to ideality, the MTZ is smaller and the diffusional resistances are minimal. Thus, the objective of this work was to investigate the effect of the flow rate on the breakthrough curves for the process of monocomponent biosorption of chromium and nickel ions by Sargassum filipendula pre-treated biomass. The concentration of ions in the feed was kept constant around 2 meq/L, while the flow rate was varied: 2, 4, 6, and 8 mL/min. The obtained results pointed out to the volumetric flow rate of 2 mL/min as the best operational condition for both systems, presenting the largest capacity of the packed bed (tu/tt) and the highest retention of metallic ions (Qtu). Key words: fixed bed, biosorption, volumetric flow rate.Em um leito fixo, o comportamento de adsorção baseia-se nas zonas de transferência de massa (ZTM). Para uma vazão de operação na qual a coluna forneça curvas de ruptura próximas a idealidade, tem-se uma menor ZTM e uma minimização das resistências difusionais. Assim, o objetivo deste trabalho foi investigar o efeito da vazão nas curvas de ruptura para o processo de biossorção monocomponente do íon cromo e níquel pela biomassa de Sargassum filipendula pré-tratada. A concentração de alimentação dos íons foi mantida constante em torno de 2 meq/L, enquanto a vazão foi variada em 2, 4, 6 e 8 mL/min. Os resultados obtidos indicaram a vazão volumétrica de 2 mL/min como a melhor condição de operação para ambos os sistemas, apresentando a maior capacidade útil do leito empacotado (tu/tt) e retenção dos íons metálicos (Qtu). Palavras-chave: leito fixo, biossorção, vazão volumétrica

Biossorção de cromo(III) em coluna de leito fixo

The chromium (III) uptake on pre-treated seaweed Sargassum filipendula biomass was investigated in fixed bed. In the experiments 8 g of the biosorbent of 2.6 mm diameter medium were deposited in the column. The operation conditions were: feed solution pH of 3, temperature of 30ºC, flow rate of 6 mL.min-1 and feed concentrations of chromium of 0.95, 1.45, 1.99, 2.82, 4.79 and 5.78 meq.L-1. The experimental equilibrium data in the column and batch systems have been analyzed using the irreversible isotherm (qmax = 1.93 meq.g-1) and the Langmuir isotherm, respectively, for simulate the sorption of chromium ion. The rupture curves obtained experimentally were modeled mathematically using a model that considers the mass transfer in the solid phase as the controlling step. The mass transfer in the solid (K) was influenced by the initial chromium concentration in the studied range. Key words: biosorption, chromium, bed fixed.A remoção de cromo (III) empregando a biomassa da alga marinha pré-tratada Sargassum filipendula foi investigada em coluna de leito fixo. Nos experimentos realizados cerca de 8 g do biossorvente de diâmetro médio 2,6 mm foram depositados na coluna. As condições de operação foram: pH da solução de alimentação de 3,0, temperatura de 30ºC, vazão de 6 mL.min-1 e concentrações de alimentação de cromo de 0,95, 1,45, 1,99, 2,82, 4,79 e 5,78 meq.L-1. Os dados experimentais de equilíbrio obtidos foram ajustados empregando o modelo da isoterma irreversível (qmax= 1,93 meq.g-1) e o modelo de Langmuir obtido em sistema batelada foram utilizados para simular a biossorção do íon cromo. As curvas de ruptura obtidas experimentalmente foram modeladas matematicamente empregando-se um modelo que considera a transferência de massa na fase sólida como etapa controladora do processo. A transferência de massa no sólido (K) foi influenciada pela concentração inicial do cromo na faixa estudada. Palavras-chave: biossorção, cromo, leito fixo

Single and multi-component adsorption of psychiatric pharmaceuticals onto alternative and commercial carbons

This work describes the adsorptive removal of three widely consumed psychiatric pharmaceuticals (carbamazepine, paroxetine and oxazepam) from ultrapure water. Two different adsorbents were used: a commercial activated carbon and a non-activated waste-based carbon (PS800-150-HCl), produced by pyrolysis of primary paper mill sludge. These adsorbents were used in single, binary and ternary batch experiments in order to determine the adsorption kinetics and equilibrium isotherms of the considered pharmaceuticals. For the three drugs and both carbons, the equilibrium was quickly attained (with maximum equilibrium times of 15 and 120 min for the waste-based and the commercial carbons, respectively) even in binary and ternary systems. Single component equilibrium data were adequately described by the Langmuir model, with the commercial carbon registering higher maximum adsorption capacities (between 272 ± 10 and 493 ± 12 μmol g-1) than PS800-150-HCl (between 64 ± 2 and 74 ± 1 μmol g-1). Multi-component equilibrium data were also best fitted by the single component Langmuir isotherm, followed by the Langmuir competitive model. Overall, competitive effects did not largely affect the performance of both adsorbents. Binary and ternary systems maintained fast kinetics, the individual maximum adsorption capacities were not lower than half of the single component systems and both carbons presented improved total adsorption capacities for multi-component solutions.publishe