Performance study of an industrial RO plant for seawater desalination

In this work, an approach to study the long-term performance of an industrial water desalination plant is described. Operational data corresponding to the time period of 454 days were analysed and from the results obtained it was found that the normalized water permeability coefficient declined by about 7%. Due mainly to the temperature effects, the salt permeability coefficient exhibit significant changes only during the summer period. The equations used allowed a good description of the performance of the plant.http://www.sciencedirect.com/science/article/B6TFX-4NF2VNK-X/1/4cb299a29681a2b1bcbca4c5bfa3d4d

Removal of Chloride in the Kraft Chemical Recovery Cycle of Pulp Mills Using the Ion-Exchange Process

High levels of chloride in the kraft recovery cycle of pulp mills can cause serious problems, particularly in recovery boiler operation. The treatment of ash collected from the electrostatic precipitator (ESP) for chloride removal was investigated experimentally using the ion-exchange process based on an amphoteric resin (BIORAD AG 11 A8). Saturation and regeneration experiments in a fixed bed were carried out for different flow rates. Experimental adsorption results obtained in the saturation step were well predicted with a mathematical model that takes into account dispersed plug flow for the bulk liquid, external mass-transfer resistance, intraparticle mass transfer by pore diffusion, and instantaneous equilibrium of adsorption at the pore/wall interface. The equilibrium was modeled using an extended Langmuir−Freundlich isotherm for three components (Cl-, SO42-, and CO32-) based on single-component equilibrium data. The resin performance was tested during cyclic operation, in which a chloride removal efficiency of higher than 89% was achieved, along with a sulfate recovery of 67−74%

Reduction of AOX in the Bleach Plant of a Pulp Mill

The reconfiguration of an existing five-stage bleaching D0E1D1E2D2 sequence is proposed to ensure the minimal formation of organochlorine compounds, expressed as AOX, in the bleach plant of a kraft pulp mill processing Eucalyptus globulus wood. This reduction of the load of AOX in the effluents can be achieved without introducing new and expensive technologies in the bleaching process. In practice, this goal can be achieved by eliminating the washing step between the D0 and the E1 stages. With this strategy, the total AOX in the liquid effluent of the bleach plant can be reduced by almost 65% while maintaining a level of 90% ISO brightness of the pulp and even diminishing the degradation of its polysaccharides. With this process redesign, the total AOX discharge from the bleach plant can be decreased from 1.2 to 0.42 kg/t prior to any biological treatment. Furthermore, the proposed modified (D0E1)D1E2D2 sequence enables the reduction of the total flow rate of effluent to be treated and also the total consumption of water, which is quite critical in these types of plants. Moreover, with this strategy, one is able to move the first drum washer of a conventional bleaching sequence to the entrance of the bleach plant. This gives rise to a cleaner pulp and therefore to lower requirements of chlorine dioxide, which in turn will enable further reductions in the global AOX generation

Highly selective solvent extraction of Zn( II ) and Cr( III ) with trioctylmethylammonium chloride ionic liquid

This study investigates the recovery of Zn(II) and Cr(III) from aqueous solutions based on solvent extraction with trioctylmethylammonium chloride [TOMA+][Cl-], commercialy named Aliquat 336. Single metal solutions and binary mixtures of both metals were considered. The effect of relevant operating conditions such as pH, contact time, initial concentration, O/A phase volumetric ratio, and temperature were evaluated. Additionally, loading capacity and stripping studies were performed. Results showed that [TOMA+][Cl−] is an effective extracting agent for Zn(II), reaching maximum removal capacity at pH 1.8 and demonstrating fast extraction kinetics. Extraction efficiencies above 99% were achieved at 0.5, 0.75, and 1.00 O/A volumetric phase ratios for 0.1 g/L initial Zn(II) concentration. At 1 g/L and 10 g/L concentration, for the same O/A ratios, approximately 88% of the initial Zn(II) was extracted. In contrast, it was found that negligible amounts of Cr(III) were transferred to the [TOMA+][Cl−] phase at the 1-5 pH range. Selectivity studies showed that Zn(II) removal is boosted in the presence of Cr(III), although no Cr(III) is extracted. [TOMA+][Cl−] exhibited a high Zn(II) storage capacity, since after 25 loading cycles with 1 g/L, the loading capacity reached approximately 13.5 g/L, and after five loading cycles with 5 g/L, the capacity reached 19.4 g/L. Stripping tests revealed that NaOH is an efficient agent for the removal of Zn(II) from the ionic liquids, reaching 98.5% removal after two cycles, whereas HNO3 is not a suitable agent, reaching less than 40% removal after three cycles. [TOMA+][Cl−] revealed high potential for separating Zn(II) from Cr(III)

Determination of the Biosorption of Cd(Ⅱ) by Coconut Fiber

Made available in DSpace on 2015-05-04T17:07:34Z (GMT). No. of bitstreams: 2 license.txt: 1914 bytes, checksum: 7d48279ffeed55da8dfe2f8e81f3b81f (MD5) mirian_pereiraetal_IOC_2014.pdf: 279050 bytes, checksum: 56b80540ed54c2c0f81bacc18831da2f (MD5) Previous issue date: 2014Universidade Federal do Rio Grande do Norte. Centro Tecnológico. Engenharia Mecânica. Natal. RN, Brasil / University of Coimbra. Centre of Chemical Processes Engineering and Forest Products (CIEPQPF), Coimbra, Portugal / Universidade Federal do Rio Grande do Norte. Faculdade de Ciências da Saúde do Traíri. Santa Cruz, RN, Brasil.Universidade Federal do Rio Grande do Norte. Centro Tecnológico. Engenharia Mecânica. Natal. RN, Brasil .Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Laboratório de Ultraestrutura Celular. Rio de Janeiro, RJ, Brasil.Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Laboratório de Ultraestrutura Celular. Rio de Janeiro, RJ, Brasil.Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Laboratório de Ultraestrutura Celular. Rio de Janeiro, RJ, Brasil.Universidade Federal do Rio Grande do Norte. Departamento de Análises Clínicas. Natal, RN, Brasil.Universidade Federal do Rio Grande do Norte. Departamento de Engenharia Têxtil. Natal, RN, Brasil.University of Coimbra. Centre of Chemical Processes Engineering and Forest Products (CIEPQPF). Coimbra, Portugal.University of Coimbra. Centre of Chemical Processes Engineering and Forest Products (CIEPQPF). Coimbra, Portugal.Universidade Federal do Rio Grande do Norte. Centro Tecnológico. Engenharia Mecânica. Natal. RN, Brasil / Fundação Oswaldo Cruz. Laboratório de Ultraestrutura Celular. Rio de Janeiro, RJ, Brasil.The coconut fiber is produced in large quantities in Brazil, even though very small quantities are being used by some industries, mainly cordage mats and handicrafts. An alternative usage would be the use of these fibers in biosorption of heavy metals from aqueous solutions. This present study aimed to evaluate the potentiality of cadmium biosorption by coconut fiber. The coconut fibers were used at kinetic analysis, influence of pH and adsorption isotherms were also carried out. It can be concluded that there is great potential for the use of coconut fiber, and the optimum pH for adsorption was around 5.0. The adsorption kinetics is fast and equilibrium occurs within 120 min. The Langmuir isotherm was considered the most suitable to describe the experimental data