Spelling suggestions: "subject:"heavy fetals - removal"" "subject:"heavy fetals - emoval""
31 |
Effects of nickel on activated sludge performance at varying COD:TKN ratiosTrahern, Patti Gremillion January 1982 (has links)
The effects of a continuous dose of 0.5 mg/l nickel on activated sludge performance at varying COD:TKN ratios were investigated. Continuous flow, complete mix, bench-scale reactors were operated over a range of mean cell residence times, and COD removal efficiency, biokinetic coefficients, extent of nitrification, and nickel removal evaluated at each. Data from two earlier studies, in which 0.5 and 1 mg/l nickel doses were applied to similar units, were included for comparison.
Organic removal efficiency was not impaired for the nickel doses considered. Biokinetic coefficients and nitrate production were also unaffected by 0.5 mg/l nickel. In contrast, one mg/l nickel sharply inhibited nitrification, caused an apparent decrease in reactor solids concentration, and related biokinetic changes in coefficients. Nickel removal was erratic. / Master of Science
|
32 |
Availability and distribution of heavy metals from sewage sludge in the plant-soil continuumRappaport, Bruce D. January 1986 (has links)
An investigation was conducted using in situ lysimeters (1.5 m x 2.3 m) to determine Cd, Cu, Ni, and Zn availabilities for barley (Hordeum vulgare L.) and corn (Zea mays L.) grown on four sludge-amended soils. These lysimeters were constructed in Acredale silt loam (Typic Ochraqualf), Bojac loamy sand (Typic Hapludult), Davidson clay loam (Rhodie Paleudult), and Groseclose silt loam (Typic Hapludult) soils. An aerobically digested sewage sludge from a sewage system with major industrial inputs was applied at rates of 0, 42, and 84 dry Mg ha-t to the lysimeters in the poorly-drained Acredale soil. Rates of 0, 42, 84, 126, 168, and 210 dry Mg ha-1 were applied to the lysimeters in the well-drained Bojac, Davidson, and Groseclose soils.
Tissue metal concentrations were determined in 1984 and 1985 for a three crop rotation, which consisted of corn, barley, and corn on the Acredale soil. Increases in sludge-borne Ni and Zn led to increases in Ni and Zn concentrations in corn earleaf, corn grain, and barley silage. Copper concentration was increased in barley silage but not in corn grain and stover. On this poorly-drained soil, metal movement did not occur below the Ap horizon even when Cu was applied in excess of USEPA guidelines. Although there were increases in metal levels, all four metals were within the range considered normal for corn and barley growth.
Soil, corn, and barley plants were sampled in 1984 and 1985 to determine Cd, Cr, Cu, Ni, and Zn availabilities for crops grown on the sludge-amended Bojac, Davidson, and Groseclose soils. Levels of DTPA-extractable Cd, Cu, Ni, and Zn in the Ap horizon of these soils increased linearly with sludge rate. Corn grain and stover yields were not decreased on the Bojac, Davidson, and Groseclose soils when 4.5, 5105, 760, 43.0, 135, and 620 kg ha-1 of Cd, Cr, Cu, Ni, Pb, and Zn were added as a sludge-amendment. Copper and Zn applied in excess of 480 and 60 kg ha- 1 of USEPA guidelines, respectively on the Bojac, Davidson, and Groseclose soils were not phytotoxic to corn plants in 1984. Corn and barley tissue sampled for three consecutive seasons had Cr concentrations <2.8 mg kg-1. / Ph. D.
|
33 |
Community responses of aquatic macroinvertebrates to heavy metals in laboratory and outdoor experimental streamsClements, William H. January 1988 (has links)
This research describes aquatic macroinvertebrate community responses to heavy metals (copper, zinc) in experimental streams and at metal-impacted sites in the field. Experiments employed substrate-filled trays which were colonized in the field and then transferred to laboratory or outdoor streams.
Laboratory experiments conducted over three seasons showed that acute (96 h) exposure to copper (Cu) at 15-32 μg Cu/L significantly reduced macroinvertebrate abundance and number of taxa during each season. Owing to differences in sensitivity among taxa, the percent composition of dominant groups varied between control and dosed streams. Mayflies were quite sensitive to Cu, particularly during the summer when water temperatures were higher.
Community responses to Cu and Zn in outdoor experimental streams were similar to those observed at metal-impacted sites in the field. Control streams and field reference Stations were dominated by mayflies and Tanytarsini chironomids. In contrast, treated Streams and impacted field sites were dominated by net-Spinning caddisflies (Hydropsychidae) and Orthocladiini chironomids. The similarity of these experimental results to those observed in the field suggest that macroinvertebrate community responses to heavy metals are highly predictable.
Responses of these communities to Cu were greatly influenced by water quality. Effects were more severe in New River Streams, where water hardness and alkalinity were low, compared to Clinch River Streams, where hardness and alkalinity were higher. In soft water Streams, abundance was reduced by 84% after 10 d exposure to Cu (measured concentration = 13 μg/L). In contrast, abundance was reduced by only 45% in hard water Streams after 10 d at Similar Cu levels. These results demonstrate the importance of accounting for water quality characteristics of receiving systems when establishing site-specific criteria for metals.
Chronic exposure (14 d) to sublethal levels of Cu (< 6 μg/L) increased Vulnerability of caddisflies (Hydropsyche morosa and Chimarra sp.) to predation by the Stonefly, Paragnetina fumosa. Caddisflies were also the major component of stonefly diets and were consumed Significantly more frequently in dosed Streams than controls. These results demonstrate that single Species bioassays were inadequate for predicting effects of toxicants on community level processes. / Ph. D.
|
34 |
Complex soil-microorganism-pollutant interactions underpinning bioremediation of hydrocarbon/heavy metal contaminated soil.Phaal, Clinton B. 14 June 2013 (has links)
This study evaluated the efficacy of bioremediation as a treatment option for a
hydrocarbon and heavy metal contaminated soil. Microbial degradation of
hydrocarbons under aerobic, nitrate-reducing and sulphate-reducing conditions was
examined. Nutrient supplementation with nitrogen and phosphate as well as aeration
seemed to be the most important factors for enhancing biodegradation. From initial
batch studies, a carbon: nitrogen ratio of 50: 1 was found to be optimal for
biodegradation. However, very low carbon to nitrogen ratios were undesirable since
these inhibited microbial activity. Manipulation of the pH did not seem to be beneficial
with regard to hydrocarbon biodegradation. However, low pH values induced elevated
concentrations of leachate heavy metals. Aerobic conditions provided optimal
conditions for hydrocarbon catabolism with up to 54% of the original contaminant
degraded after 2 months of treatment. Further treatment for up to 20 months did not
significantly increase hydrocarbon biodegradation. Under nitrate- and sulphatereducing
conditions, 6% and 31 % respectively of the initial contaminant was degraded
after 2 months while after a further 20 months, 50% and 42%, respectively were
degraded. The addition of soil bulking agents and the use of sparging did not
significantly increase biodegradation. Similarly, the addition of inoculum did not
influence biodegradation rates to any great degree. The presence of heavy metals up
to concentrations of 400 mgt1 Mn, 176 mgt1 Zn and 94 mgt1 Ni did not reduce microbial
activity within the soil. During the treatment phase, heavy metal and hydrocarbon
migration were limited even under water saturation and low pH conditions. A
Biodegradation Index was developed and evaluated and may, potentially, find use as
an in situ assessment technique for microbial hydrocarbon catabolism. The
iodonitrophenyltetrazolium salt assay was also found to be an effective and rapid
alternative assay for monitoring bioremediation progress. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 1996.
|
35 |
Assessment of a Mycorrhizal Fungi Application to Treat Stormwater in an Urban BioswaleMelville, Alaina Diane 05 July 2016 (has links)
This study assessed the effect of an application of mycorrhizal fungi to stormwater filter media on urban bioswale soil and stormwater in an infiltration-based bioswale aged 20 years with established vegetation. The study tested the use of commercially available general purpose biotic soil blend PermaMatrix® BSP Foundation as a treatment to enhance Earthlite™ stormwater filter media amelioration of zinc, copper, and phosphorus in an ecologically engineered structure designed to collect and infiltrate urban stormwater runoff before it entered the nearby Willamette River.
These results show that the application of PermaMatrix® BSP Foundation biotic soil amendment to Earthlite™ stormwater filter media contributed to the reduction of extractable zinc in bioswale soil (-24% and -26%), as compared to the control, which received a treatment of Earthlite™ stormwater filter media only, and experienced an increase in extractable zinc levels (23% and 39%). The results presented also show evidence that after establishment mycorrhizal treatment demonstrated lowered levels of phosphorus in bioswale soil (-41%) and stormwater (-100%), in contrast to the control, which had increased phosphorus levels. The treatment contributed to reductions between 67% and 100% in every metric detected in stormwater after an establishment period of 17 weeks, while the bioswale with no mycorrhizal treatment had increases between 50% and 117%. Treatment also appeared to enhance the reduction of ammonium and nitrates, while contributing to a greater increase in soil pH.
|
36 |
Sorption of heavy metals by laterite from Vinh Phuc and Hanoi, VietnamNguyen, Hoang Phuong Thao, Nguyen, Thi Hoang Ha, Bui, Thi Kim Anh 07 January 2019 (has links)
This study was carried out to evaluate the sorption capacity of Pb, As, Cd, Zn, and Mn by laterite from Tam Duong District (Vinh Phuc Province) and Thach That District (Hanoi City). Laterite samples were exposed to different initial concentrations of heavy metals in solutions (2.5, 5.0, 10, 20, and 50 mg/l) at pH = 5.5 during 24 hours. The results demonstrated that sorption capacity of heavy
metals was in the following order: Pb> As> Cd> Zn>Mn. The highest sorption capacity of Pb, As, Cd, Zn, and Mn of laterite from Tam Duong was 1553, 756, 397, 281, and 143 mg/kg, respectively and the highest removal efficiency was 94, 76, 70, 56 and 37%. The results indicated that laterite from Tam Duong District showed lower sorption capacity than that from Thach That District. The
disparity sorption capacity of Pb, As, Cd, Zn, Mn between laterite from Thach That and Tam Duong was 10.3–11.6, 11.9–17.9, 11.5–13.7, 9.5–17.6, and 11.1–14.3%, respectively. Laterites from Tam Duong and Thach That are a promising environmental material which can be used in the removal of heavy metals from wastewater. / Nghiên cứu này được thực hiện nhằm đánh giá khả năng hấp phụ Pb, As, Cd, Zn, và Mn bởi laterit đá ong khu vực huyện Tam Dương (Vĩnh Phúc) và huyện Thạch Thất (Hà Nội). Mẫu đá ong được tiến hành thí nghiệm trong các dung dịch có hàm lượng kim loại nặng ban đầu khác nhau (2,5; 5,0; 10; 20 và 50 mg/l) tại pH=5,5 trong 24 giờ. Kết quả nghiên cứu cho thấy mức độ hấp phụ kim loại nặng bởi laterit đá ong lần lượt là Pb> As> Cd> Zn>Mn. Dung lượng hấp phụ Pb, As, Cd, Zn và Mn cao nhất của laterit Tam Dương lần lượt là 1553, 756, 397, 281 và 143 mg/kg và hiệu suất hấp phụ cao nhất lần lượt là 94, 76, 70, 56 và 37%. Dung lượng hấp phụ kim loại nặng của laterit huyện Tam Dương thấp hơn khu vực huyện Thạch Thất. Sự chênh lệch về dung lượng hấp phụ Pb, As, Cd, Zn và Mn giữa laterit Thạch Thất và laterit Tam Dương lần lượt là 10,3–11,6; 11,9–17,9; 11,5– 13,7; 9,5–17,6 và 11,1–14,3%. Kết quả nghiên cứu bước đầu cho thấy đá ong khu vực huyện Tam Dương và Thạch Thất là vật liệu hấp phụ tiềm năng phục vụ ứng dụng trong xử lý nước thải bị nhiễm kim loại nặng.
|
37 |
Magnetic adsorption separation process for industrial wastewater treatment using polypyrrole-magnetite nanocomposite.Muthui, Muliwa Anthony. January 2013 (has links)
M.Tech. Engineering: Chemical. / Aims at demonstrating the application of semi-continuous and continuous magnetic adsorption separation (MAS) techniques to extract Cr (VI) ions from wastewater streams using PPy-Fe3O4 nanocomposite. Specifically, the research aims to achieve the following objectives: to design, synthesize and characterize new generation PPy-Fe3O4 nanocomposite with varied magnetite composition for hexavalent chromium removal ; to generate batch adsorption kinetic data in a continuously stirred tank reactor (CSTR) and apply existing kinetic models to aid in water treatment system design.; to design and construct magnetic adsorption separation (MAS) device that can operate in a semi-continuous and continuous mode and explore their performances and to optimize the systems' performance.
|
38 |
Sunkiųjų metalų šalinimas iš nuotėkų dumblo elektrocheminiu būdu / Heavy Metals Removal from Sewage Sludge using Electrochemical MethodBarišauskas, Giedrius 05 June 2005 (has links)
SUMMARY
Heavy Metals Removal from Sewage Sludge using Electrochemical Method
Giedrius Barišauskas
Magister thesis, 50 pages, 14 figure, 7 tables, 85 references.
Research object – municipal sewage sludge.
Research subject – electrochemical removal of heavy metals from sewage sludge.
Aim of this study – to investigate the efectiveness of electrochemical Pb, Cd and Cu removal from simulated heavy metal solutions and liquid organic wastes.
Tasks – to analyze scientific literature as well as normative documents regulating quality parameters of organic wastes and their products used in agriculture in respect of heavy metals. To investigate variation of Pb, Cd and Cu concentrations in Kaunas and Raseiniai sewage sludge; to carry out laboratory experiments of Pb, Cd and Cu removal from model heavy metal solutions as well as sewage sludge, evaluating decrease of both mobile and total metal concentrations.
Methods and instrumentation – following methods have been applied: chemical extraction (preparation of samples), gravitometric, ionometric, atomic absorption spectrophotometric. Results were evaluated using methods of statistical analysis.
Results – in case of monocomponent simulated heavy metal solutions 60–90 efficiency have been reached after 10 hours of electrochemical treatment, while in multicomponent systems and natural liquid sludge the removal percentage appeared to be lower. Depending upon removal from sludge efficiency heavy metals ranked in the... [to full text]
|
39 |
Remoção de metais pesados (Cd, Pb, Zn) utilizando como adsorventes argilas nacionais: Chocobofe e Chocolate B. / Removal of heavy metals (Cd, Pb, Zn) using as adsorbent national clays: Chocobofe and Chocolate B.SILVA, José Vanderley do Nascimento. 16 March 2018 (has links)
Submitted by Johnny Rodrigues (johnnyrodrigues@ufcg.edu.br) on 2018-03-16T18:41:45Z
No. of bitstreams: 1
JOSÉ VANDERLEY DO NASCIMENTO SILVA - TESE PPGEQ 2015..pdf: 2308601 bytes, checksum: 9f12a4c2a7b8abc9470ef017ee29755e (MD5) / Made available in DSpace on 2018-03-16T18:41:45Z (GMT). No. of bitstreams: 1
JOSÉ VANDERLEY DO NASCIMENTO SILVA - TESE PPGEQ 2015..pdf: 2308601 bytes, checksum: 9f12a4c2a7b8abc9470ef017ee29755e (MD5)
Previous issue date: 2015-02 / Capes / O aumento da produção industrial tem proporcionado à geração de efluentes aquosos contaminados com íons de metais pesados. Esses devem ser tratados antes de serem descartados no meio ambiente. Por este motivo é muito importante à utilização de processos para reduzir ou eliminar metais pesados presentes em efluentes industriais. Dentre os vários processos existentes, a adsorção apresenta grande eficiência na remoção de metais presentes em baixas concentrações. As argilas têm apresentado ótimos resultados em processos de adsorção de metais pesados, o que motiva a busca por argilas que possuam maior afinidade com cada tipo de metal. Neste trabalho as argilas naturais esmectiticas Chocobofe e Chocolate B proveniente do estado da Paraíba foram investigadas com o objetivo de avaliar sua afinidade e capacidade para remoção de cádmio, chumbo e zinco. Realizou-se, inicialmente, a caracterização das argilas pelas técnicas: Difração de Raios X; Análises químicas; Análises térmicas (diferencial e gravimétrica); Espectroscopia na região do infravermelho; Adsorção Física de Nitrogênio; Microscopia eletrônica de varredura e capacidade de troca de cátions. Depois de caracterizadas, as argilas foram avaliadas quanto a sua capacidade de remoção (qeq) e seu percentual de remoção (%Rem) para os metais (Cádmio, Chumbo e Zinco), presentes em efluente sintético, através de sistema de banho finito. De forma a se obter uma maior eficiência na remoção dos metais, foi realizado um planejamento fatorial 22 avaliando duas variáveis de entrada: concentração inicial de metais pesados (10, 30 e 50 ppm) e pH (3, 4 e 5), para determinar as melhores condições de trabalho, no qual se
verificou que o pH= 5 e concentração inicial de 50 mg/g foram as condições que
apresentaram melhores resultados alcançando Valores de 88,54-99,44% de
percentagem de remoção e 3,36-4,43 mg/g de capacidade de remoção. A partir
desses dados foram desenvolvidos estudos cinéticos e isotermas de equilíbrio que
serviram de dados para avaliar a capacidade de adsorção das argilas com ajustes
feitos através dos modelos de Langmuir, Freundlich e Redlich-Peterson. Os
resultados dos testes cinéticos indicaram que o processo de remoção dos íons Cd2+,
Pb2+ e Zn2+ pelas argilas se aplicam ao mecanismo do modelo de velocidade de
pseudo-segunda ordem, sendo necessário um tempo de 10 minutos para alcançar o
equilíbrio. Os modelos matemáticos adotados para a modelagem dos dados
experimentais descreveram adequadamente a dinâmica da adsorção, produzindo
isotermas teóricas com comportamento bastante próximos daqueles encontrados
com as isotermas experimentais e que dos modelos utilizados, verifica-se que os
modelos de Langmuir e Redlich-Peterson apresentaram melhor ajuste aos dados
experimentais. A capacidade máxima de adsorção obtida pelas argilas Chocobofe e
Chocolate B foram: 18,35 -21,88 mg. g-1 para o Pb2+; 10,0-11,20 mg. g-1 para o Cd2;
8,64-8,69 mg.g-1 para o Zn2, indicando uma seletividade das argilas em relação aos
metais em estudo uma sequência de afinidade: Pb2+ > Cd2 > Zn2. Assim, os
resultados experimentais indicaram que as argilas bentonitas podem ser utilizadas
como adsorventes para a eliminação dos metais Cádmio, Chumbo e Zinco de aguas
e efluentes contaminados por meio do mecanismo de adsorção. / The increase in industrial production has provided the generation of wastewater
contaminated with heavy metal ions. These must be treated before disposal into the
environment. For this reason it is very important to the use of processes to reduce or
eliminate heavy metals from industrial effluents. Among the many existing processes,
adsorption has great efficiency in the removal of metals present in low
concentrations. Clays have shown excellent results in heavy metal adsorption
processes, which motivates the search for clays having higher affinity with each type
of metal. In this work the smectite clays natural Chocobofe and Chocolate B from the
state of Paraíba were investigated in order to evaluate their affinity and capacity for
the removal of cadmium, lead and zinc. Held, initially, the characterization of clays by
techniques: X-ray diffraction; Chemical analysis; Thermal analysis (differential and
gravimetric); Spectroscopy in the infrared region; Adsorption Nitrogen Physics;
Scanning electron microscopy and capacity of cation exchange. After characterized
the clays were evaluated for removal capacity (q and q) and its removal percentage
(% Rem) to metals (cadmium, lead and zinc) present in synthetic wastewater through
finite bath system. In order to achieve greater efficiency in the removal of metals a 22
factorial experimental design was conducted to evaluate two input variables: initial
concentration of heavy metals (10, 30 and 50 ppm) and pH (3, 4 and 5) to determine
the best working conditions, which revealed that the pH = 5 and initial concentration
of 50 mg/g were the conditions that showed better results from 88.54 to 99.44%
reaching values of percentage removal and 3,36- 4.43 mg/g of removability. From
these data were developed kinetic and equilibrium isotherms that served data to
evaluate the adsorption capacity of clays with adjustments made through the
Langmuir, Freundlich and Redlich-Peterson. The results of the kinetic tests indicated
that the removal of Cd2+ ions, Pb2+ and Zn2+ the clay are applied to the mechanism of
the pseudo-second-order rate model, a time of 10 minutes is required to reach
equilibrium. The mathematical models used to model the experimental data
adequately describe the dynamics of adsorption, producing theoretical isotherms
quite close to those found behavior with experimental isotherms and that of the
models used, it appears that the Langmuir and Redlich-Peterson showed better fit to
the experimental data. The maximum adsorption capacity obtained by clays
Chocobofe and Chocolate B were 18.35 -21.88 mg. g-1 for Pb2+; 10.0 to 11.20 mg. g-1
for Cd2+; 8.64 to 8.69 mg.g-1 for Zn2+, indicating a selectivity of clays in relation to
studying a metal affinity sequence: Pb2+> Cd2+> Zn2+. Thus, the experimental results
indicate that the bentonite clays can be used as adsorbents for the removal of metals
cadmium, lead and zinc contaminated water and effluent by adsorption mechanism.
|
40 |
Humic acid pretreatment for enhancing microbial removal of metals from a synthetic 'wastewater'.Desta, Tsegazeab Goje. January 2004 (has links)
The presence of heavy metal ions in waste streams is one of the most pervasive
environmental issues of present times. A rotating biological contactor (RBC) was used
to investigate the potential capacity of microbial biofilms in remediation of the metal
ion species from a mixed metal contaminated effluent solution containing Cr+3
, Pb+2
and Cu+2
, each at a concentration of 200 mg r1
• In the first part of this study the
effectiveness of various support materials for the development of microbial biofilms
capable of removing heavy metals from a synthetic effluent was investigated. EDX
analysis showed that none of the support matrices investigated, viz. gravel, polyester
batting and sand, adsorbed metal ions on their surfaces; hence, metal adsorption was
due purely to microbial activities. The biofilms attached more firmly and uniformly to
polyester batting than to gravel and sand. The characteristics of polyester batting which
made it a superior support matrix were its surface roughness and porous hydrophilic
nature, which provided a larger surface area for the adhesion of microorganisms and
attraction of nutrients during the biofilm development process.
The selective accumulation of metal ion specIes by various microbial populations
grown as biofilm using polyester batting as support matrix in separate compartments of
a single-stage RBC bioreactor was examined. Lead ions were readily accumulated by
almost all the microbial biofilms tested. Fungus-dominated biofilms selectively
accumulated chromium ions whereas biofilms comprising mainly bacteria more readily
accumulated copper ions from the mixed metal contaminated effluent solution.
However, where interactions between the bacterial and fungal components were
encouraged the mechanical stability of the biofilms was enhanced so that large amounts
of all three metal ion species were removed by this biofilm.
The combined effect of a series of bench-scale columns containing liquid humic acid
and a three stage RBC bioreactor on the removal of metal ion species from a mixed
metal contaminated effluent was investigated. After seven days of treatment the
combined system had removed approximately 99% of the Cr+3, 98% of the Pb+2 and 90% of the Cu+2 ions from the mixed metal contaminated synthetic effluent.
Complexation of the metal ions with humic acid was the predominant factor accounting
for approximately 68-86% Cr+3
, 70-86% Pb+2 and 53-73% Cu+2 removal levels within
the columns. A large proportion of the remaining Cr+3 and Pb+2, but not of the Cu+2,
was removed in compartment 1 of the RBC. This suggested that the presence of the
former two metals in solution might have reduced the removal of the Cu+2 ions from the
system. The removal of substantially large amounts of the competing ions chromium
and lead during the initial stages of the treatment process meant that copper was
successfully taken up in the second and third RBC compartments. Hence, the economy
of the treatment process was improved as larger quantities of the metal ions were
removed in a shorter period of time than was possible when using the individual
treatments (humic acid-metal complexation and biofilm adsorption) separately. More
than 75%,92% and 86% of the adsorbed Cr+3
, Pb+2 and Cu+2 ions, respectively, were
recovered from the three RBC bioreactor compartments following repeated washing of
the biofilms with 0.1 M HCI. This relatively easy desorption suggested that the metal
ions were simply adsorbed onto the surfaces of the biofilm cells rather than being taken
into the cytoplasm of the cells. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2004.
|
Page generated in 0.1815 seconds