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Development of a heavy metal sorption system through the P=S functionalization of coconut (Cocos nucifera) fibers

SOUSA, Dayane Almeida de; OLIVEIRA, Elisabeth de; NOGUEIRA, Marcio da Costa; ESPOSITO, Breno Pannia
Fonte: ELSEVIER SCI LTD Publicador: ELSEVIER SCI LTD
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
55.93%
Lignocellulosic residues are interesting materials for the production of heavy metal adsorbents for aquatic systems. Whole fibers taken from coconut (Cocos nucifera) husks were functionalized with the thiophosphoryl (P=S) group by means of the direct reaction with CI(3)P=S, (CH(3)O)(2)CIP=S or (CH(3)CH(2)O)(2)CIP=S in order to obtain an adsorptive system for `soft` metal ions, particularly Cd(2+). These functionalized fibers (FFs) were characterized by means of elemental analysis, infrared spectroscopy, thermal analysis and acid-base titration. Adsorption isotherms for Cd(2+) fitted the Langmuir model, with binding capacities of 0.2-5 mmol g(-1) of FF at 25 degrees C. (C) 2009 Elsevier Ltd. All rights reserved.; Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); FAPESP; CNPq; Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Removal of Pb2+ from aqueous solutions using two Brazilian rocks containing zeolites

Shinzato, M. C.; Montanheiro, T. J.; Janasi, Valdecir de Assis; Andrade, S.; Yamamoto, Jorge Kazuo
Fonte: SPRINGER; NEW YORK Publicador: SPRINGER; NEW YORK
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
56.01%
The removal of Pb2+ from aqueous solution by two Brazilian rocks that contain zeolites-amygdaloidal dacite (ZD) and sandstone (ZS)-was examined by batch experiments. ZD contains mordenite and ZS, stilbite. The effects of contact time, concentration of metal in solution and capacity of Na+ to recover the adsorbed metals were evaluated at room temperature (20A degrees C). The sorption equilibrium was reached in the 30 min of agitation time. Both materials removed 100% of Pb2+ from solutions at concentrations up to 50 mg/L, and at concentrations larger than 100 mg/L of Pb2+, the adsorption capacity of sandstone was more efficient than that of amygdaloidal dacite due to the larger quantities and the type of zeolites (stilbite) in the cement of this rock. All adsorbed Pb2+ was easily replaced by Na+ in both samples. The analysis of the adsorption models using nonlinear regression revealed that the Sips and the Freundlich isotherms provided the best fit for the ZS and ZD experimental data, respectively, indicating the heterogeneous adsorption surfaces of these zeolites.; Fundacao de Amparo a Pesquisa do Estado de Sao Paulo; Fundacao de Amparo a Pesquisa do Estado de Sao Paulo [03/06259-4]

"Tratamento de esgoto pelo sistema de lodos ativados no município de Ribeirão Preto, SP: avaliação da remoção de metais pesados" ; "Sewage treatment through the activated sludge system in Ribeirão Preto, SP: evaluation of heavy metal removal"

Oliveira, Aline da Silva
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 01/02/2006 PT
Relevância na Pesquisa
66.2%
Os sistemas de tratamento de esgotos sanitários são considerados como requisitos básicos de infra-estrutura para as sociedades urbanas, pois possibilitam o controle e a prevenção de muitas doenças, gerando condições de higiene que promovem a saúde pública. Considerando os elementos constituintes dos efluentes urbanos e industriais, além da carga microbiológica, podem conter diversos poluentes químicos que afetam a saúde humana. Dentre os constituintes químicos, destacam-se os metais pesados que, se não devidamente removidos durante o processo de tratamento, podem causar uma poluição significativa no corpo receptor, representando um risco para a saúde humana e ambiental. Em Ribeirão Preto – SP há em funcionamento duas estações de tratamento de esgotos (ETE) sendo a ETE-Caiçara, desde o ano de 2000 e a ETE-Ribeirão Preto, desde 2002. Este estudo teve como objetivo avaliar os níveis de metais pesados em efluentes urbanos, antes e após o tratamento de esgoto pelo sistema de lodos ativados da ETE-Ribeirão Preto. Visou também avaliar os níveis de metais pesados no lodo formado durante o tratamento de esgoto pelo sistema de lodos ativados, considerando sua possível utilização para fins agrícolas. No esgoto bruto e tratado foram analisados os seguintes metais: Cd...

Produção e caracterização de quitosana imobilizada em substratos visando adsorção de ions metalicos; Production and characterization of chitosan immobilized on substrates targeting metal ions adsorption

Juliana Queiroz Albarelli
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 15/12/2009 PT
Relevância na Pesquisa
66.03%
A quitosana é um polímero natural muito estudado devido à sua boa capacidade adsorvente. A aplicação deste biopolímero para remoção de metais pesados tem sido estudada desde o início dos anos 1970 sendo que o número de trabalhos sobre este tema cresceu rapidamente desde então. No entanto, o uso da quitosana como adsorvente em maior escala enfrenta alguns obstáculos, devido à sua baixa resistência mecânica. Uma possível alternativa para melhorar aspectos mecânicos e que também contribui para uma melhor transferência de massa do adsorbato no adsorvente é a imobilização da quitosana em matrizes sólidas utilizando-se técnicas de recobrimento de partículas. Neste contexto, este trabalho visou investigar a imobilização da quitosana em substratos para a aplicação em sistemas de adsorção. Inicialmente foram testados como suporte para imobilização da quitosana vidro, polipropileno, borracha vulcanizada, porcelana e tecido de algodão. O substrato de vidro, utilizado na forma de esferas, apresentou melhor interação com a solução de recobrimento e características adequadas para aplicação em processos de adsorção. As esferas de vidro foram recobertas por diferentes métodos utilizando quitosana 2,5% (m/v) em solução de ácido acético 3% (v/v). O material recoberto foi utilizado em sistemas de adsorção em batelada e contínuo a fim de se analisar a capacidade de remoção de cobre pelo filme de quitosana. Dentre as diferentes técnicas de revestimento estudadas...

Biosorption of heavy metal and dyes : a promising technology leather wastewater treatment

Rosales, E.; Pazos, M.; Sanromán, M. A.; Tavares, M. T.
Fonte: Centro para a Valorização de Resíduos (CVR) Publicador: Centro para a Valorização de Resíduos (CVR)
Tipo: Conferência ou Objeto de Conferência
Publicado em 04/03/2011 ENG
Relevância na Pesquisa
56.23%
The presence of dyes and heavy metals is usual in industrial processes like chrome tanning in tannery industry and their removal may be an environmental problem. Different techniques were developed and applied for the treatment of dyes and heavy metals in effluents. Among them, adsorption showed to be an economic, simple operation and an effective technique. Zeolites have a strong affinity for cations of transition metals, but only little affinity for anions and non-polar organic molecules. The application of a zeolite to heavy metal removal may be improved by the presence of microorganisms. The aim of this work is the treatment of an effluent containing dyes and toxic metals. Several operation parameters such as pH, concentration and kinetic behavior were studied. This innovative process for treating dyes and heavy metal effluents showed that the zeolite-biomass system is able to perform the removal of a combination of Azure B and chromium(VI). A mixture of dye and metal solutions was treated reaching a removal higher than 50% in the case of chromium (VI) and higher than 99% for dye, in 8 days.

Characterization of desmodesmus pleiomorphus isolated from a heavy metal-contaminated site: biosorption of zinc

Monteiro, Cristina M.; Marques, Ana P. G. C.; Castro, Paula M. L.; Malcata, F. Xavier
Fonte: Springer Verlag Publicador: Springer Verlag
Tipo: Artigo de Revista Científica
Publicado em //2009 ENG
Relevância na Pesquisa
56.19%
Microalgae have been proven efficient biological vectors for heavy metal uptake. In order to further study their biosorption potential, a strain of Desmodesmus pleiomorphus (L) was isolated from a strongly contaminated industrial site in Portugal. Under different initial Zn2? concentrations, metal removal by that strain reached a maximum of 360 mg Zn/g biomass after 7 days, at 30 mg Zn/l, after an initial rapid phase of uptake. Comparative studies were carried out using a strain of the same microalgal species that is commercially available (ACOI 561): when exposed to 30 mg Zn/l, it could remove only 81.8 mg Zn/g biomass. Biosorption experiments using inactivated biomass of the isolated strain reached a maximum Zn2? uptake of 103.7 mg/g. Metal removal at various initial pH values was studied as well; higher removal was obtained at pH 5.0. The microalga strain L, isolated from the contaminated site, exhibited a much higher removal capacity than the commercial strain, and the living biomass yielded higher levels of metal removal than its inactivated form.

Biosorption of zinc ions from aqueous solution by the microalga Scenedesmus obliquus

Monteiro, Cristina M.; Castro, Paula M. L.; Malcata, F. Xavier
Fonte: Universidade Católica Portuguesa Publicador: Universidade Católica Portuguesa
Tipo: Artigo de Revista Científica
Publicado em //2011 ENG
Relevância na Pesquisa
56.13%
Aquatic environments are often exposed to toxic heavy metals, which gain access to the food chain via microalgae and may cause severe problems at higher trophic levels. However, such a metabolic specificity can be taken advantage of in bioremediation strategies. The potential of a novel wild strain of Scenedesmus obliquus, previously isolated from a heavy metal-contaminated site in northern Portugal, to remove Zn from aqueous solutions was thus studied, using several initial concentrations. The removal extent reached its maximum by 1 day: 836.5 mg Zn/g biomass, at the initial concentration of 75 mg/L, mainly by adsorption onto the cell surface. Comparative studies encompassing a commercially available strain of the same microalgal species led to a maximum removal extent of only 429.6 mg Zn/g biomass, under identical conditions. Heat-inactivated cells permitted a maximum removal of 209.6 mg Zn/g biomass, at an initial concentration of 50 mg Zn/L. The maximum adsorption capacity of Zn, estimated via Langmuir’s isotherm, was 330 mg Zn/g biomass. Finally, Zn removal was highest at pH 6.0–7.0. It was proven, for the first time, that such a wild microalga can uptake and adsorb Zn very efficiently, which unfolds a particularly good potential for bioremediation. Its performance is far better than similar (reference) species...

Characterization of plant antioxidative system in response to abiotic stresses: a focus on heavy metal toxicity

Mourato, Miguel; Reis, Rafaela; Martins, Maria Luísa Louro
Fonte: InTech Publicador: InTech
Tipo: Parte de Livro
Publicado em /04/2012 ENG
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56.05%
During their life span, plants can be subjected to a number of abiotic stresses, like drought, temperature (both high and low), radiation, salinity, soil pH, heavy metals, lack of essential nutrients, air pollutants, etc. When affected by one, or a combination of abiotic stresses, a response is induced by changes in the plant metabolism, growth and general development. Reactive Oxygen Species (ROS) are a natural consequence of the aerobic metabolism, and plants have mechanisms to deal with them in normal conditions, controlling the formation and removal rates. Under stress conditions, cell homeostasis is disrupted and ROS production can increase a lot putting a heavy burden on the those antioxidative mechanisms, some of which are activated in order to eliminate the excess ROS (Mittler et al., 2004). Trace element contamination cause abiotic stress in plants and it can affect crop production and quality. Certain metals, like copper, are essential for plants, but at high concentrations (depending on plant species) can be considered toxic. Other elements like cadmium and arsenic (a metalloid), while not essential elements for plants, are widespread pollutants that are present in nature due to both natural and manmade activities. Plants have developed different strategies to cope with these stresses. Some use an avoidance strategy to reduce trace element assimilation while others use internal defence mechanisms to cope with the increasing levels of the toxic species. Phytotoxic amounts of trace elements are known to affect several physiological processes and can cause oxidative stress. Plants have developed several trace element defence mechanisms...

Heavy metals removal in dual media filters

Santos, Pedro Deyrieux Centeno Ogando
Fonte: Faculdade de Ciências e Tecnologia Publicador: Faculdade de Ciências e Tecnologia
Tipo: Dissertação de Mestrado
Publicado em //2012 ENG
Relevância na Pesquisa
56.13%
Dissertação para obtenção do Grau de Mestre em Engenharia do Ambiente – Perfil de Engenharia Sanitária; The purpose of this study was to investigate physicochemical mechanisms for the removal of heavy metals from the effluent of Harnaschpolder’s WWTP Pilot Installation in the South of Netherlands. This effluent is partially submitted to tertiary treatment in a water reuse pilot which aims the production of water for two different end‑uses: crop irrigation in greenhouses and surface‑type water. Tertiary filters were mounted and started up at the reuse pilot and specific concentrations of heavy metals were dosed in the filters. Removal efficiencies were then calculated after the end of the experiments. As a parallel research project, the removal of HM was also carried out by inoculating selected bacteria (biosorption). Solubility curves were calculated for the dosed heavy metals (Cd, Cu, Ni, Zn) using PHREEQc programme, to predict if heavy metal precipitation occurred in the filters (using the same experimental data: temperature, pH , alkalinity, etc.). Results show that physicochemical precipitation was not the primary removal mechanism for heavy metals. The results suggest that other mechanisms such as adsorption and/or chelation may be involved in the removal of these species.

Biosorption of Mn (II), Co (II) and Cr (VI) in a horizontal rotating tubular bioreactor: experiments and evaluation of the integral bioprocess model

Rezić,T.; Rezić,I.; Zeiner,M.; Hann,S.; Stingeder,G.; Šantek,B.
Fonte: Brazilian Society of Chemical Engineering Publicador: Brazilian Society of Chemical Engineering
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/09/2014 EN
Relevância na Pesquisa
56.05%
In this research, a multi heavy metals removal process with mixed microbial culture was examined in a horizontal rotating tubular bioreactor (HRTB) with different combinations of process parameters. Three metals were selected as examples of cations (manganese and cobalt) and oxy-anion (hexavalent chromium). Hydrodynamic conditions and biomass sorption capacity in the HRTB had the main impact on the heavy metals removal efficiencies, which were for Mn2+ 87.0-93.6%, Co2+ 89.0-95.7% and Cr6+ 99.7-100%, respectively. For the bioprocess description in the HRTB, the integral bioprocess model that combines hydrodynamics, mass transfer and kinetics was used. This model was evaluated for the new experimental conditions and average variances between experimental and simulated data were in the range of 0.12 - 3.21·10-3. The results obtained clearly show that the integral bioprocess model is able to describe the heavy metal removal process in the HRTB.

Studies on heavy metal removal efficiency and antibacterial activity of chitosan prepared from shrimp shell waste

Mohanasrinivasan, V.; Mishra, Mudit; Paliwal, Jeny Singh; Singh, Suneet Kr.; Selvarajan, E.; Suganthi, V.; Subathra Devi, C.
Fonte: Springer Berlin Heidelberg Publicador: Springer Berlin Heidelberg
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
66.03%
Chitosan, a natural biopolymer composed of a linear polysaccharide of α (1–4)-linked 2-amino 2-deoxy β-d glucopyranose was synthesized by deacetylation of chitin, which is one of the major structural elements, that forms the exoskeleton of crustacean shrimps. The present study was undertaken to prepare chitosan from shrimp shell waste. The physiochemical properties like degree of deacetylation (74.82 %), ash content (2.28 %), and yield (17 %) of prepared chitosan indicated that that shrimp shell waste is a good source of chitosan. Functional property like water-binding capacity (1,136 %) and fat-binding capacity (772 %) of prepared chitosan are in total concurrence with commercially available chitosan. Fourier Transform Infra Red spectrum shows characteristic peaks of amide at 1,629.85 cm−1 and hydroxyl at 3,450.65 cm−1. X-ray diffraction pattern was employed to characterize the crystallinity of prepared chitosan and it indicated two characteristic peaks at 10° and 20° at (2θ). Scanning electron microscopy analysis was performed to determine the surface morphology. Heavy metal removal efficiency of prepared chitosan was determined using atomic absorption spectrophotometer. Chitosan was found to be effective in removing metal ions Cu(II)...

A novel approach to exploit indigenous mining algal-microbes in a photo-rotating biological contactor for heavy metal removal from acid mine drainage

Orandi, S.; Lewis, D.; Eslami, A.; Mohebbi, A.
Fonte: IMWA; Australia Publicador: IMWA; Australia
Tipo: Conference paper
Publicado em //2013 EN
Relevância na Pesquisa
66.07%
Extremophilic acidic microbial biofilms, that thrive in acidic mine drainages (AMD), are well known as natural metal-resistant biosorbents for removing heavy metals throught active and passive cellular functions. To benefit from the resistant and cleansing nature of these microorganisms and to develop a system applicable to mining sites, an indigenous AMD biofilm was immobilized in a laboratory scale photo-rotating biological contactor (PRBC) to investigate its heavy metal removal potential from AMD. The microbial consortium used for biofilm development contained filamentous green micro-algae, bacteria, fungi and yeasts, collected from AMD and the Sarcheshmeh copper mine in Iran. The PRBC was operated with synthesised AMD representing the multi-ion and acidic composition of the wastewater (composing 18 elements with a pH of 3.5+0.3) from which the microbial consortium was collected. Light, nutrient dosing and rotational speeds were optimised to encourage biofilm development. Electron microscopy was used to monitor the development of the algal-microbial biofilm on the PROBC discs over a 60 day batch mode operation. The PRBC was then run continuously with a 24 h hydraulic residence time (HRT) over a ten week period. The weekly average of water analysis results demonstrated the ability for the algal-microbial biofilm to remove 15-50% of various metals in the order of Cu> Ni> Mn> Zn> Sb> Cr> Co> Al. These results clearly indicate the significant potential for indigenous AMD biofilm to be exploited within a PRBC for AMD treatment.; http://www.imwa.info/imwa-meetings/proceedings/264-proceedings-2012.html; Sanaz Orandi...

Biofilm establishment and heavy metal removal capacity of an indigenous mining algal-microbial consortium in a photo-rotating biological contactor

Orandi, S.; Lewis, D.; Moheimani, N.
Fonte: Nature America Inc Publicador: Nature America Inc
Tipo: Artigo de Revista Científica
Publicado em //2012 EN
Relevância na Pesquisa
66.12%
An indigenous mining algal-microbial consortium was immobilised within a laboratory-scale photo-rotating biological contactor (PRBC) that was used to investigate the potential for heavy metal removal from acid mine drainage (AMD). The microbial consortium, dominated by Ulothrix sp., was collected from the AMD at the Sar Cheshmeh copper mine in Iran. This paper discusses the parameters required to establish an algal-microbial biofilm used for heavy metal removal, including nutrient requirements and rotational speed. The PRBC was tested using synthesised AMD with the multi-ion and acidic composition of wastewater (containing 18 elements, and with a pH of 3.5 ± 0.5), from which the microbial consortium was collected. The biofilm was successfully developed on the PRBC's disc consortium over 60 days of batch-mode operation. The PRBC was then run continuously with a 24 h hydraulic residence time (HRT) over a ten-week period. Water analysis, performed on a weekly basis, demonstrated the ability of the algal-microbial biofilm to remove 20-50 % of the various metals in the order Cu > Ni > Mn > Zn > Sb > Se > Co > Al. These results clearly indicate the significant potential for indigenous AMD microorganisms to be exploited within a PRBC for AMD treatment.; S. Orandi...

BATCH AND BENCH-SCALE FIXED-BED COLUMN EVALUATIONS OF HEAVY METAL REMOVALS FROM AQUEOUS SOLUTIONS AND SYNTHETIC LANDFILL LEACHATE USING LOW-COST NATURAL ADSORBENTS

Li, Chenxi
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado Formato: 5000314 bytes; application/pdf
EN; EN
Relevância na Pesquisa
76.23%
In this project, three separate experiments were conducted to assess heavy metal removal from metal aqueous solutions and synthetic landfill leachate by adsorption using low-cost natural adsorbents. Fundamental batch investigations indicated that the 4.0-4.75 mm crushed mollusk shells and the Sphagnum peat moss were the best adsorbents for cadmium and nickel removal, respectively. Peat moss was also found to have the highest adsorption capacities for manganese and cobalt adsorption. The adsorption capacities of the peat moss and crushed mollusk shells used as natural adsorbents for the adsorption of cadmium and nickel from binary aqueous solutions in fixed-bed columns under continuous flow conditions were investigated. The life expectancy of each adsorbent in the fixed-bed columns was also assessed for different hydraulic loading rates. The flow rate of 1.5 mL/min (surface loading of 27.52 cm3/cm2•day) and bed depth of 15 cm were identified as the better operational conditions from the column testing. The results indicated that 47.9% and 42.7% cadmium and nickel removal efficiencies could obtained under these operational conditions, respectively. Finally, the peat moss and the crushed mollusk shells were packed in bench-scale down-flow fixed-bed columns to evaluate their adsorption capacities as natural low-cost adsorbents for the removal of heavy metals from aerated and non-aerated synthetic landfill leachate. The flow rate applied in this operation was 1.5 mL/min (surface loading of 27.52 cm3/cm2•day). Peat was found to have the best adsorption capacities in columns treating aerated synthetic leachate for cadmium (78.6%) and nickel (83.8%) removal efficiencies.; Thesis (Master...

Heavy metal removal from MSS fly ash by thermal and chlorination treatments

Liu, Jingyong; Chen, Jiacong; Huang, Limao
Fonte: Nature Publishing Group Publicador: Nature Publishing Group
Tipo: Artigo de Revista Científica
Publicado em 25/11/2015 EN
Relevância na Pesquisa
66.2%
The thermal behavior of heavy metals in the co-incineration of municipal solid waste-sludge incinerator fly ash (MSS fly ash) was studied using a laboratory-scale tube furnace. The results indicate that without the addition of chlorinating agents, temperature was an important parameter and had significantly influenced on heavy metal removal, whereas the residence time had a weak effect. Between 900 and 1000 °C for 60 to 300 min, heavy metals reacted with chloride-inherent in the fly ash, and approximately 80 to 89% of Pb, 48% to 56% of Cd, 27% to 36% of Zn and 6% to 24% of Cu were removed. After the adding chlorinating agents, the evaporation rate of the heavy metals improved dramatically, where the evaporation rates of Cu and Zn were larger than that of Pb and Cd. As the amount of added chlorinating agents increased, the removal rate of heavy metals increased. However, the effect of the type of chlorinating agent on the chlorination of heavy metals differed considerably, where NaCl had the weakest effect on the removal rate of Cu, Cd and Zn. In terms of resource recovery and decontamination, MgCl2 and CaCl2 are the best choices due to their efficient removal of Zn.

Heavy metal removal by yeast strains

Marques, Paula A. S. S.; Pinheiro, H. M.; Teixeira, J. A.; Rosa, M. F.
Fonte: Universidade do Minho Publicador: Universidade do Minho
Tipo: Conferência ou Objeto de Conferência
Publicado em 10/09/1996 ENG
Relevância na Pesquisa
56.06%
Cu'2+ removal from aqueous solutions (O.1mM) was compared using viable cells of two yeast strains, grown both in the presence and in the absence of the metal. The flocculent yeast strain (S. cerevisiae NRRL Y265) presented significantly higher removal yields in both cases (respectively, 62 and 99% versus 7 and 12% for the non-flocculent strain of S. carlsbergensis). The effect of the ion metal concentration on the biosorption capacity of S. cerevisiae NRRL Y265 was also tested in aqueous solutions of Cu 2'+, Cd'2+ and Pb2'+ ( 0.1, 0.25, 0.5 and 1mM). Cells were more efficient for Pb2'+ removal (90-100%) than for the others, being Cu 2'+ the least biosorbed ion. While for Pb 2' + there was no yield modification with concentration, for the other ·two ions a significant yield decrease was observed with the increase of ion concentration. On the contrary, in aqueous mixtures of two or three of these cations, only for the highest concentration tested (1mM) was a removal yield decrease observed. Similar data were obtained with non-viable cells of another flocculent yeast from a brewing. industry (UNICER). In every system analysed...

Removal Of Metals From Laboratory Solutions And Landfill Leachate By Greensand Filters

Spoljaric, N.; Crawford, W.A.
Fonte: Newark, DE: Delaware Geological Survey, University of Delaware Publicador: Newark, DE: Delaware Geological Survey, University of Delaware
Tipo: Relatório
EN_US
Relevância na Pesquisa
55.93%
Distilled water spiked with heavy metal cations was passed at a rate of 2-4 ml/min through a filter composed of greensand containing about 80 percent glauconite. The capability of the greensand to trap metal cations is increased by prolonging the contact time between the leachate and the greensand. Flushing the charged greensand filter with water does not cause significant release of cations back into solution, suggesting that polluted greensand might be disposed in landfills without adding pollutants to either ground or surface water in the vicinity.

Electrochemical technology for removing heavy metals present in synthetic produced water

Souza,K. R.; Silva,D. R.; Mata,W.; Martínez-Huitle,C. A.; Mata,A. L. M. L.
Fonte: Latin American applied research Publicador: Latin American applied research
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/04/2012 EN
Relevância na Pesquisa
55.99%
The performance of an electrocoagulation (EC) system with aluminium and iron electrodes for removing heavy metal ions (Cd2+, Cu2+, Cr3+, Sr2+ and Zn2+) present in synthetic produced water on laboratory scale was studied systematically. Experimental parameters such as applied current, flow effluent and sacrificial electrodes were investigated in order to understand their influence on the EC process. Increasing the current density accelerated the electrocoagulation process, but made it less efficient. Cd2+, Cu2+, Sr2+ and Zn2+ showed similar removal rates, under similar conditions, indicating a uniform electrochemical behavior. The study gave indications on the removal mechanisms of the investigated metals. Cd2+, Cu2+ and Zn2+ ions are hydrolyzed and co-precipitated as hydroxides. Cr4+, was proposed to be reduced first to Cr3+ at the cathode before precipitating as hydroxide. The process expenditure was estimated and reported showing the viability of this process as a green alternative, obtaining modest costs using Fe electrodes.

Removal of nutrient and heavy metal loads from sewage effluent using vetiver grass, Chrysopogon zizanioides (L.) Roberty

Mudhiriza,T; Mapanda,F; Mvumi,BM; Wuta,M
Fonte: Water SA Publicador: Water SA
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/07/2015 EN
Relevância na Pesquisa
56.08%
Urban cities in many developing nations face the challenge of relieving the pressure exerted on overloaded sewage treatment works. Apart from limited financial capacity, complementary treatment methods like phyto-extraction of pollutants from the effluent have not been fully exploited, particularly in southern Africa. A study was conducted in Harare, Zimbabwe, to assess the potential of vetiver grass, Chrysopogon zizanioides, in removing N, P, Zn, Mn and Ni loads in sewage effluent from primary clarification, under hydroponic conditions. Vetiver grass was grown from tillers on floating trays suspended in effluent, and the total concentrations of selected parameters were monitored in both effluent and vetiver grass at 0, 7, 14 and 21 days of retention in effluent. Higher pollutant reduction (62-100%) in effluent, with respect to all parameters, under vetiver grass compared to no vetiver treatment (9-27%), was recorded by Day 21. Effluent pH remained stable at 7.44-7.64. Smaller changes were found for N (9.8 from 27.5 mg.ℓ-1) and P (2.0 from 5.3 mg.ℓ-1) than for the heavy metals. Vetiver grass dry biomass accumulated at 3.8-4.7 g-tiller-1-week-1, while heavy metal extraction (up to 6.2 mg Zn, 3.3 mg Mn and 0.06 mg Ni tiller-1) by root uptake increased with time at an exponential rate (R²...

Industrial effluent treatments using heavy-metal removing bacterial bioflocculants

Lin,J; Harichund,C
Fonte: Water SA Publicador: Water SA
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/04/2011 EN
Relevância na Pesquisa
55.98%
Bioflocculants produced by Herbaspirillium sp. CH7, Paenibacillus sp. CH11, Bacillus sp. CH15 and a Halomonas sp. were preliminarily evaluated as flocculating agents in the treatment of industrial wastewater effluents. Industrial (1 local chemical-industry and 2 textile-industry: Biavin 109-medium blue dye and Whale dye) effluent (9 mℓ) containing various heavy metals was vortexed with 1 mℓ of bioflocculant in a 25 mℓ test tube. One mℓ of water (Millipore Elix purification system, 17 megaΩ) was substituted for the bioflocculant in the control. After 5 min, the heavy metal concentrations, the microbial population and the turbidity of the top layer of the industrial effluent were determined using ICP-OES, spread-plate technique and a turbidity meter respectively. The flocculating activity was calculated based on absorbance at a wavelength of 550 nm. Bioflocculants produced in this study were capable of removing several heavy metals from industrial effluents simultaneously and effectively. This was significant (p < 0.05) when applied to Biavin medium blue dye, with 95% of Cr2+ and 94% of Ni2+ removed by the presence of bioflocculants. Bioflocculants also removed almost all of the bacteria and reduced 50-80% of the turbidity of the chemical effluent sample...