scholarly journals Removal of heavy metals derived from COD analysis wastewater by electrolysis using graphite electrode

2021 ◽  
Vol 63 (3) ◽  
pp. 85-91
Author(s):  
Thi Thanh Diem Ngo ◽  
◽  
Minh Tien Tran ◽  
Keyword(s):  
Heavy Metals ◽  
High Efficiency ◽  
Low Cost ◽  
Treatment Method ◽  
High Concentration ◽  
Graphite Electrodes ◽  
Efficient Treatment ◽  
High Concentrations ◽  
Recycle And Reuse ◽  
A Current

In this study, electrolysis using graphite electrodes was applied to treat wastewater generated from a COD analysis procedure (referred to as COD wastewater). COD wastewater containing high concentrations of H2SO4, Hg2+, and Cr2O72- salts were collected and then treated by electrolysis with graphite electrodes in a lab-scale experiment. The results showed that the electrolysis process was not affected by the electrode’s distance or area. The most efficient treatment for all three metals was achieved at a current value of 31.58 mA, which corresponds to a current density of 1.974 mA/cm2 under a voltage of 3 V, 8-h electrolysis time, wastewater pH<1, electrode distance of 4 cm, and electrode area of 16 cm2. Under these conditions, the concentrations of heavy metals after treatment were 1170.17 mg/l for Hg, 871.20 mg/l for Ag, and 56.3 mg/l for Cr. The treatment efficiencies were 48.15, 66.94, and 50.76%, for Hg, Ag, and Cr, respectively. While this technology is simple, low cost, and achieves a relatively high efficiency, after treatment the COD wastewater still carried a high concentration of heavy metals that exceeded the permissible standards. Therefore, it is necessary to have a further treatment method in place to completely eliminate the heavy metals remaining in wastewater, as well as to recycle and reuse acidic components from wastewater and to treat them up to environmental standards before discharge. In conclusion, electrolysis with graphite electrodes can be applied in practice to treat other sources of wastewater contaminated by heavy metals with low emissions.

Australian Biosolids: Characterization and Determination of Available Copper

2004 ◽  
Vol 1 (2) ◽  
pp. 116 ◽  
Author(s):  
Ian W. Oliver ◽  
Graham Merrington ◽  
Mike J. McLaughlin
Keyword(s):  
Heavy Metals ◽  
Agricultural Land ◽  
Low Cost ◽  
Land Application ◽  
Toxic Heavy Metals ◽  
High Concentration ◽  
Protection Factor ◽  
Metal Concentrations ◽  
Total Metal ◽  
High Concentrations

Environmental Context. Land application of sewage-derived biosolids is both an inexpensive method to dispose of waste and a simple way to increase soil fertility and stability. However, biosolids often contain high concentrations of heavy metals, but not all of the metals are immediately available for uptake by the soil or other organisms. To determine if this toxicologic risk outweighs the benefits, the degree of ecologically available metal, rather than simply the entire metal content, must be known in both the as-disposed and worst conditions scenarios. Application of these principles requires regulatory bodies to amend their guidelines. Abstract. Application of biosolids to agricultural land provides a low-cost disposal option with many potential benefits to soil. However, the practice may result in accumulations of potentially toxic heavy metals, and thus regulations are in place to limit the amount of metals applied to soil in this way. Current Australian regulations are not ideal because they are based on total metal concentrations in soils and biosolids, rather than the fraction that is ecologically available (the fraction accessible by organisms). Therefore more environmentally appropriate regulations, based on the available metal portion, need to be devised. However, before this is possible, more needs to be known about the characteristics of Australian biosolids, including the factors that influence the availability of biosolid metals. Copper is a metal of great concern because of its commonly high concentration in biosolids and because of its relatively high toxicity to certain groups of bacteria and fungi. Therefore an investigation was conducted to characterize the range of properties observed in Australian biosolids, and to determine the fraction of available metals and the factors that influence it (particularly in the case of copper). General properties such as pH, electrical conductivity, organic carbon, and total metal concentrations were measured. Availability of copper was specifically measured using isotopic exchange techniques and a Cu2+ ion-selective electrode. Results showed that total copper concentration and Cu2+ activity could be used to predict available copper. A new system of biosolid land-use regulation that incorporates the available metal fraction and a pH protection factor is proposed.

Graphite Electrodes for Hydrogen Production by Acid Electrolysis

2020 ◽  
Vol 1012 ◽  
pp. 158-163
Author(s):  
Oliveira Marilei de Fátima ◽  
Mazur Viviane Teleginski ◽  
Virtuozo Fernanda ◽  
Junior Valter Anzolin de Souza
Keyword(s):  
Hydrogen Production ◽  
Fossil Fuels ◽  
High Efficiency ◽  
Low Cost ◽  
Electric Energy ◽  
Gas Production ◽  
Hydrogen Fuel Cells ◽  
Graphite Electrodes ◽  
Alkaline Electrolysis ◽  
Selection Of

Nowadays, humanity has become aware of the consequences that the use of fossil fuels entails, and the latest developments in the energy sector are leading to a diversification of energy resources. In this context, researching on alternative forms of producing electric energy is being conducted. At the transportation level, a possible solution for this matter may lie in hydrogen fuel cells. The electrolysis of water is one of the possible processes for hydrogen production, but the reaction to break the water molecule requires a great amount of energy and this is precisely the biggest issue involving this process. In this work, low cost electrodes of 254 stainless steel and electrolytic graphite were used for hydrogen production, allowing high efficiency and reduced oxidation during the process. The selection of these materials allows to obtain a high corrosion resistance electrolytic pair, by replacing the high cost platinum electrode usually employed in the alkaline electrolysis process. The formic acid of biomass origin was used as an electrolyte. It was observed that the developed reactor have no energy losses through heat and it was possible to obtain approximately 82% conversion efficiency in the gas production process.

scholarly journals Contamination of Soil and Plant By the Hazaribagh Tannery Industries

2017 ◽  
Vol 43 (2) ◽  
pp. 207-222 ◽  
Author(s):  
MN Mondol ◽  
A Asia ◽  
AS Chamon ◽  
SMA Faiz
Keyword(s):  
Heavy Metals ◽  
Metropolitan Area ◽  
Food Chain ◽  
Environmental Concern ◽  
Dry Season ◽  
High Concentration ◽  
Wet Season ◽  
Industrial Activities ◽  
Plant Samples ◽  
High Concentrations

An investigation was made at Hazaribagh Tannery area, comprising about 145 industries in Dhaka Metropolitan area. The analyses of soil and plant samples showed that heavy metals contribute significantly towards environmental contamssination resulting from industrial activities. Concentration of heavy metals (Cr, Zn, Pb, Cd, Mn, Fe and Ni) in soil and plant samples cross the MAC (Maximum allowable concentration) in both wet and dry season. In case of soil sample the highest concentration of Cr (172792 ppm) was found at main disposal point. Chromium, Zn, Pb, Cd, Mn, Fe and Ni concentrations at Hazaribagh plant samples respectively ranged from 171-1348, 247-777, 45-96, 1.66-2.17, 72-231, 354-787, and 18-38 ppm respectively in dry season and 75-1142, 209-691, 29- 84, 1.02-2.00, 66-124, 331-664, 11-37 ppm respectively in wet season. Concentration went down gradually with increasing distance from the main disposal point (spot 1). But again high concentration (150708 ppm of Cr) was noted in spot 6. Similar results were found for plant samples. High concentrations of heavy metals were found in plant samples which consequently affect food chain, which may be a major environmental concern. Asiat. Soc. Bangladesh, Sci. 43(2): 207-222, December 2017

Recent Progress on Adsorption Materials for Phosphate Removal

2019 ◽  
Vol 13 (1) ◽  
pp. 3-16 ◽  
Author(s):  
Saeed Ahmed ◽  
Muhammad Naeem Ashiq ◽  
Dianqing Li ◽  
Pinggui Tang ◽  
Fabrice Leroux ◽  
...  
Keyword(s):  
High Performance ◽  
High Efficiency ◽  
Low Cost ◽  
Development Trend ◽  
Phosphate Removal ◽  
High Concentration ◽  
The Public ◽  
Removal Capacity ◽  
Detailed Search ◽  
Double Hydroxides

Background: High concentration of phosphate has been threatening human health and the ecosystem. Adsorption is one of high-efficiency and low-cost techniques to reduce the concentration of phosphate. This mini review aims to summarize the recent development of adsorption materials for phosphate removal. Method: We conducted a detailed search of “adsorption of phosphate” in the published papers and the public patents on the adsorbents for phosphate based on Web of Science database in the period from January 1 2012 to December 31 2017. The corresponding literature was carefully evaluated and analyzed. Results: One hundred and forty one papers and twenty two recent patents were included in this review. An increased trend in scientific contributions was observed in the development of adsorption materials for phosphate removal. Three kinds of promising adsorbents: layered double hydroxides, natural materials, and metal oxides were paid special attention including removal mechanism, performance as well as the relationship between adsorption performance and structure. Both the chemical composition and the morphology play a key role in the removal capacity and rate. Conclusion: The findings of this review confirm the importance of phosphate removal, show the development trend of high-performance and low-cost adsorption materials for phosphate removal, and provide a helpful guide to design and fabricate high-efficiency adsorbents.

scholarly journals Heavy metals in tributaries of Pampulha Reservoir, Minas Gerais

2001 ◽  
Vol 61 (3) ◽  
pp. 363-370 ◽  
Author(s):  
A. C. RIETZLER ◽  
A. L. FONSECA ◽  
G. P. LOPES
Keyword(s):  
Heavy Metals ◽  
Water Quality ◽  
Water Quality Management ◽  
Sampling Period ◽  
Control Site ◽  
High Concentration ◽  
Wet Season ◽  
Initial Portion ◽  
High Concentrations ◽  
Belo Horizonte

A great amount of heavy metals enter Pampulha Reservoir via it's main tributaries (Sarandi and Ressaca). Although no water quality classification has been carried out for these tributaries, the reservoir is expected to be in class 2 of the CONAMA-86 system. As part of a monitoring scheme of the Pampulha Watershed, heavy metals (Zn, Pb, Cd, Ni, Cu, Cr, Mn and Fe) were investigated in the water at a control site (considered free from direct human influence) and at potential sites of toxicity and contamination during August (dry season) and November (wet season) of 1998. The results for the first sampling period showed relatively high concentrations of zinc (0.22 mg.L<FONT FACE=Symbol>-</FONT>1) in the upper portion of the reservoir. The highest values of nickel and chromium (0.19 and 0.89 mg.L<FONT FACE=Symbol>-</FONT>1, respectively) were found in the initial portion of the Sarandi Stream, while the highest concentrations of lead (0.05 mg.L<FONT FACE=Symbol>-</FONT>1), cadmium (0.014 mg.L<FONT FACE=Symbol>-</FONT>1), manganese (0.43 mg.L<FONT FACE=Symbol>-</FONT>1) and iron (15.25 mg.L<FONT FACE=Symbol>-</FONT>1) were detected in the Ressaca Stream by the landfill dump of Belo Horizonte. A relatively high concentration of cadmium was also detected at the confluence of the two streams. During the second sampling period, there was an increase in the concentrations of zinc at all sampling sites except the control, with values varying from 0.71 mg.L<FONT FACE=Symbol>-</FONT>1 (the Sarandi Stream) to 2.50 mg.L<FONT FACE=Symbol>-</FONT>1 (the Ressaca Stream). Lead, cadmium, nickel and chromium concentrations were also higher in the Ressaca Stream, but not detected at the other sampling sites. Copper values were higher than in the first period: 0.10 mg.L<FONT FACE=Symbol>-</FONT>1 at the control up to 0.38 mg.L<FONT FACE=Symbol>-</FONT>1 at the confluence of the streams. Similar results were found for manganese and iron, with values reaching up to 19.30 and 125 mg.L<FONT FACE=Symbol>-</FONT>1, respectively. Moreover, all values recorded in the second sampling period were much higher than recommended for class 2 waters. These results emphasize the need for such monitoring in relation to better water quality management of this reservoir.

Study of Gas Production by Anaerobic Fermentation and Microbial Community Changes by In-Situ Microaerobic Desulphurization

2020 ◽  
Vol 14 (4) ◽  
pp. 517-523
Author(s):  
Yan Zhou ◽  
Hucheng Liu ◽  
Wei Kou ◽  
Lijie Shao ◽  
Peihan Liu ◽  
...  
Keyword(s):  
High Throughput Sequencing ◽  
High Efficiency ◽  
Anaerobic Fermentation ◽  
Low Cost ◽  
Total Solid ◽  
Common Species ◽  
Gas Production ◽  
High Concentration ◽  
Fermentation System ◽  
The Stability

The enhancement of biogas quality at low cost and high efficiency process was one of the purposes of biogas engineering. In this work, we designed a reactor for microaerobic desulphurization. We used this reactor to study the anaerobic fermentation in systems that used cow manure with total solid (TS) concentrations of 18.5%, 15% and 10%. The influence of anaerobic fermentation on the stability of gas production and the characteristics of the gas produced with different concentrations of fermentation materials was studied. The strain structure of the fermentation system was obtained by high-throughput sequencing and taxonomy was compared. The H2S removal results showed that the average rates of the H2S removal in concentrations of fermentation materials of 18.5%, 15%, and 10% TS were 99.2%, 97.8%, and 78.8%, respectively. 16SrRNA sequencing was performed in different fermented samples as well as a comparison between samples in order to determine the number of unique species (NUS) and the number of common species (NCS). By comparing TS 18.5 with TS 15 and TS 10 samples, it was determined that under fermentation conditions, NUS were 113 and 106, respectively. Whereas NUS were 31 and 41, respectively, when comparing TS 15 and TS 10. These demonstrated that the number of strain species in the fermentation system with TS 18.5% was far more than those found in the systems with low concentration of fermentation. Also, the ability for disturbance resistance of the microaerobic desulphurization system was stronger at high concentration of the fermentation.

scholarly journals Feasibility of Different Drying Methods to Remedy Deep-sea Mining Tailings Using the Formation of Alginate-rhamnolipid Complexes With Harmful Heavy Metals Contained in Manganese Nodules

2020 ◽  
Author(s):  
Aleum Lee ◽  
KYOUNGREN KIM
Keyword(s):  
Heavy Metals ◽  
Deep Sea ◽  
High Performance ◽  
High Efficiency ◽  
Drying Methods ◽  
Manganese Nodules ◽  
Performance Technology ◽  
Good Potential ◽  
High Concentrations ◽  
High Temperature Drying

Abstract This study investigated the usability of two drying methods to recover heavy metals contained in manganese nodules. Materials containing harmful heavy metals would be discharged during deep-sea mining processes. To improve the efficiency of future remediation practices, high-performance technology should have to be applied. Herein, two nontoxic and bio-derived substances, alginate and rhamnolipids, were used to form complexes. The complexes formed a complicated alginate-rhamnolipid (Alg-Rh) structure and that could prohibit heavy metals from being discharged by solidifying them within the complex. The content, appearance, composition, and particles of the Alg-Rh complexes formed by two drying methods—freeze-drying and high-temperature drying—were studied. In particular, metal compositions were observed between the different drying methods. These methods were found to provide good potential for remediating high concentrations of target heavy metals. Therefore, these findings can be used as a basis for future remediation technologies, including useful heavy metal recovery and high-efficiency separation.

scholarly journals INFLUENCE OF CHLORIDES AND SULPHATES ON QUALITY OF BIOLOGICAL WASTEWATER TREATMENT USING ENZYME PREPARATIONS

2004 ◽  
Vol 12 (3) ◽  
pp. 91-95 ◽  
Author(s):  
Audra Skaisgiriene ◽  
Pertas Vaitiekūnas ◽  
Vytenis Zabukas
Keyword(s):  
Biological Treatment ◽  
High Efficiency ◽  
Low Cost ◽  
Energy Levels ◽  
Sewage Treatment ◽  
Treatment Method ◽  
Active Sludge ◽  
Enzyme Preparations ◽  
Biochemical Oxygen Consumption

The biological treatment method is widely used in Lithuania due to its high efficiency, low cost and suitability for treating various types of wastewater. After technological processes various mineral substances, such as chlorides and sulphates, get into water bodies. These substances are not removed from wastewater by the biological treatment method. The purpose of this study is to determine the concentrations of chlorides and sulphates, investigate the influence of enzyme preparations upon quality and energy consumption and assess energy changes in the trophic food chain during biological treatment. To analyse the mineral salt influence of the biooxidation process a series of laboratory tests was carried out: biochemical oxygen consumption (BOD), activated sludge concentration and other indexes. It is found experimentally that a 400 mg/1 concentration of chlorides disarranges the activity of microorganisms, and at a 700 mg/1 concentration active sludge is no longer suitable for biological treatment. Also, we investigated the effect of a ferment preparation “Roebic” on effluence of sewage treatment. In a tank with an enzyme the total amount of energy after treatment increases by 5–30 %. It is determined by calculating the accumulation of energy in an active‐sludge system that an enzyme preparation increases the energy levels of the system.

scholarly journals The efficacy of European fruit lecanium, Parthenolecanium corni (Bouché, 1844) control using natural products

2019 ◽  
Vol 46 (No. 4) ◽  
pp. 195-200
Author(s):  
Michal Skalský ◽  
Jana Niedobová ◽  
Jan Popelka
Keyword(s):  
Pest Management ◽  
Plant Extract ◽  
Canola Oil ◽  
High Efficiency ◽  
Cropping Systems ◽  
High Concentration ◽  
Natural Insecticide ◽  
Synthetic Pesticides ◽  
High Concentrations ◽  
Effective Product

European fruit lecanium, Parthenolecanium corni (Bouché, 1844) is among the leading worldwide pests of fruits such as plums, currants, jostaberry, grapevine and many others. This study is focused on testing the effectiveness of natural insecticide treatments compared with conventional insecticides on overwintering nymphs of the European fruit lecanium. In February of 2017, two experiments were conducted under laboratory conditions. The tested products were Boundary SW<sup>®</sup> (plant extract), Konflic<sup>®</sup> (plant extract), Ekol<sup>®</sup> (canola oil) and a tank-mix of Ekol<sup>®</sup> + Reldan 22<sup>®</sup> (canola oil and chlorpyrifos-methyl) as a chemical standard. The most effective product tested was the chemical standard tank-mix of Ekol<sup>®</sup> and Reldan 22<sup>®</sup>, which was 100% effective in all experiments. High efficiency was also achieved with Ekol<sup>®</sup> (canola oil) in high concentrations. We can summarize, that using canola oil in high concentration has almost the same effect as the chemical standard. Using canola oil against European fruit lecanium meets the principles of Integrated Pest Management (IPM) and also the need to design cropping systems that are less dependent on synthetic pesticides.

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