Reduction Of Heavy Metals Research Articles

Thermal Effects.

This review focuses on the research literature published in 2017 relating to thermal effects in wastewater and solid waste treatment. This review is divided into the following sections: wastewater treatment, recovery of nitrogen and phosphorus, membrane technology, reduction and recovery of heavy metal, and treatment and disposal of solid waste.

Removal of Heavy Metals and Metalloids by Amino‐Modified Biochar Supporting Nanoscale Zero‐Valent Iron

Nanoscale zero-valent iron (nZVI), an environmentally benign material, has been used to remove heavy metals and metalloids from the aqueous phase because of its high reactivity and abundant reactive sites. To improve the stability of nZVI, nanoscale zero-valent iron supported by amino-modified biochar (ZVIA-BC) was prepared and characterized. Its ability to remove heavy metals and metalloid was investigated. Fourier transform infrared spectroscopy analyses showed that the amino group was chemically bound to the functional groups of biochar. X-ray photoelectron spectroscopy (XPS) and X-ray diffraction revealed that zero-valent iron was loaded on the biochar surface. High-resolution transmission electron microscope images showed that the particle size of iron was ∼50 nm and the particles consisted of roughly spherical cores covered with a shell that was uniformly 2- to 3-nm thick. Furthermore, measuring the zeta potentials at various pH values indicated that the iso-electric points occurred within the pH range of 7.50 to 7.56. Additionally, heavy metals and metalloids, including Cd(II), Ni(II), Cu(II), Cr(VI) and As(V) adsorption isotherms, on ZVIA-BC were significantly nonlinear, and ZVIA-BC exhibited a superior ability to remove these heavy metals and metalloids, especially for Cr(VI) and As(V). Characterization with high-resolution XPS revealed that reduction of heavy metals and metalloids occurred on the surface of ZVIA-BC. The main mechanisms for removal were reduction, complexation, co-precipitation, and electrostatic interaction.

The Potential Use of Pottery Jugs as Drinking Water Filters

The use of porous pottery jugs (fired clay) to the purification of drinking water and reductionof heavy metals and other contaminants is the aim of this study. A total of twenty-eight samplesof drinking tap water tested for pH, Turbidity, TDS, Electrical Conductivity, Salinity, TH, Ca++hardness, Mg++ hardness and Total Coliform bacteria, in addition to some heavy metals (Pb, Zn,Mn, Fe, Cd and Cu) in water before and after filtration also inside the jugs through 24 hour. Thepaper discusses the ability for this technique to reduce such these pollutants that may beremaining after treatment. Pottery jugs (B) represented the best one in WQI and AWQI that maybe due to its composition of silt and the high quality of clay. Pottery jugs (B) able to reduce theconcentrations of turbidity, TH, Ca++ and Mg++ hardness. Also, improved its efficiency indecreasing levels of some heavy metals as Mn, Pb, and Cd. Statistical ANOVA tests showed asignificant difference between pottery jugs with physicochemical parameters and filtrationefficiencies. The concentrations of examined physicochemical parameters and heavy metals indrinking tap water and inside the pottery jugs and in the filtrate were within the safe limits ofEMH (2007), WHO (2011) and Egyptian Standards (EEAA, 1994) regulations, except theconcentration of Fe inside and in the filtrate, was above safe limit.

Reduction of histamine and heavy metals in mackerel hydrolyzates produced by catalysts associated-subcritical water hydrolysis

Various catalysts such as formic acid, acetic acid, sodium hydroxide, sodium bicarbonate, carbon dioxide and nitrogen gas were used for hydrolyzates production from deoiled mackerel muscle by subcritical water hydrolysis. Above 99% hydrolysis yield was obtained using sodium bicarbonate catalyst at 260°C/70bar. Histamine and heavy metals concentration were reduced in hydrolyzates. Highest amount of amino acid (400.36mg/g) and reducing sugar (24.75mg/g) were found in hydrolyzate obtained at 260°C/70bar and 220°C/30bar, respectively with sodium bicarbonate catalyst. Antioxidant and ACE-inhibitory activities were significantly higher in hydrolyzates obtained using sodium bicarbonate than that of others.

Feasibility Study of Chromium Removal from Paint Sludge with Biological Sludge, Using Vermicompost by Eisenia fetida (Case Study: Saipa Automotive Industry)

Background: During the paint spraying process in the automotive industry, a variety of wastes, including a large amount of paint sludge is produced, which contains a variety of hazardous substances, such as BTEX and heavy metals. The aim of the present study was vermicomposting of paint sludge with sewage sludge and Eisenia fetida as earthworm spices for reduction of heavy metals. Objectives: Vermicomposting process employing earthworms is increasingly being used for conversion of both sewage and some industrial wastes to reduced heavy metals and volatile solid content in bulk of solid wastes. Therefore, in this study, feasibility of chromium removal from paint sludge by using Eisenia fetida worms was investigated. Methods: In this study, the quantitative and qualitative characteristics of paint and biological sewage sludge waste were determined in terms of Cr+6, moisture content, nitrogen and carbon, C/N ratio, pH and temperature. Then the paint sludge was mixed in various proportions with the thickening biological sewage sludge of Saipa’s sewage treatment plant. The decomposition time for the vermicompost samples for each run was 90 days. In order to analyze various parameters, including Cr+6 and volatile solids reduction, sampling from each pilot was performed on 1, 15, 30, 50, 70 and 90 days. The Cr+6 measurements were performed using the AASM method. The paint sludge and sewage sludge were mixed in different ratios. After the mixing, 500 adult Eisenia fetida earthworms were introduced to each box. Results: The results showed that the optimum removal rate for Cr+6 was found in the mixing ratio of 6 kg of biological sludge with 600 g of paint sludge and in this ratio, the amount of Cr+6 concentration fell from 6 mg/kg to less than 0.2 mg/kg in 90 days. In addition, in the same ratio of sludge mixing, the C/N ratio ranged from about 27 on the first day to 14.3 on day 90 and the pH decreased from 7.8 on the first day to 7.3 on the 90th day. Volatile solids decreased from 80.4% on the first day to 37% on the 90th day. Conclusions: Vermicomposting is a good alternative for treating paint sludge with biological sludge, and is advantageous for reduction of pollutants purposes. Research was carried out on bioavailability of heavy metals such as Cr+6 during vermicomposting for 90 days using Eisenia fetida earthworms. Finally, the results showed that, Eisenia fetida could eliminate Cr+6 in low levels.

Reduction of heavy metals content in contaminated vegetables due to the post-harvest treatments

Heavy metals highly contaminated samples of potato, tomato, and cucumber were used to study the effects of washing, shelling and soaking (in vinegar 5% for 5 min.) on heavy metals reduction. Heavy metal levels were determined for untreated and treated samples using Atomic Absorption Spectrophotometer and the reduction ratios of heavy metal levels were calculated. The vinegar (acetic acid) effect could be due to its effect on the pH value that influences the solution chemistry of the heavy metals such as hydrolysis, complexation by organic and inorganic ligands, redox reactions, precipitation and the adsorption availability of the heavy metals. For potato, the results revealed that washing and shelling have removed high ratio of heavy metals, however the reduction was not sufficient to decrease the levels of Pb and Cd to be within the MRLs. While soaking in vinegar in addition to washing and shelling of potato has led to a significant decrease in Pb and Cd concentrations being lower than the MRLs. For tomato and cucumber, the Cd element was not detected after washing of both vegetable kinds. Lead level in tomato was significantly decreased to the MRLs values when washed and shelled, while Pb level in cucumber was still higher than MRLs.

Treatment of the textile industry effluent in a pilot-scale vertical flow constructed wetland system augmented with bacterial endophytes

A pilot-scale vertical flow constructed wetland (VFCWs) system was designed, implemented and operated for one year for the treatment of dye-rich real textile effluent. Brachiaria mutica was vegetated to develop VFCWs in which five different textile effluent degrading endophytic bacteria were inoculated. These bacteria were screened based on their dye degrading and plant growth promoting capabilities. The system's performance was evaluated by monitoring physicochemical parameters, nutrients removal, heavy metals reduction, detoxification potential, and persistence of endophytic bacteria in the plant rhizo- and endosphere. Although VFCWs were able to remove a majority of the pollutants from the wastewater, bacterial augmentation further enhanced the remediation efficiency. The system promoted an increase in dissolved oxygen up to 188% and, concomitantly, a substantial decrease in the chemical oxygen demand (81%), biochemical oxygen demand (72%), total dissolved solids (32%), color (74%), nitrogen (84%), phosphorous (79%), and heavy metals [Cr(97%), Fe(89%), Ni(88%), Cd(72%)] was recorded. Wastewater treated with VFCWs augmented with bacteria was found to be non-toxic and inoculated bacteria showed persistence in the root and shoot interior of B. mutica. Conclusively, VFCWs proved to be an effective methodology for treatment of textile effluent whereas its smaller size with high efficiency is an advantage for field-scale applications.

Enhanced biotreatment of acid mine drainage in the presence of zero-valent iron and zero-valent copper

Abstract Batch laboratorial experiments were conducted to evaluate the potential of Fe0, Cu0 and sulfate-reducing bacteria (SRB) for reduction and removal of sulfate and heavy metals from synthetic acid mine drainage. The variation in solution pH indicates that the Fe0/Cu0 bimetallic system provided favorable conditions for SRB growth and sulfate reduction. When the SO42− concentration of wastewater was 3,000 mg/L, the SO42− removal efficiency was 51.6% for the SRB system, 76.3% for the Fe + SRB system, and 92.0% for the Fe/Cu + SRB system. Moreover, Pb2+, Cu2+ and Zn2+ ions were completely removed. The results demonstrate that the Fe/Cu + SRB system had apparent advantages over the SRB system, especially at low pH. This study demonstrates that an Fe/Cu + SRB system could be a promising technology for treating wastewater containing high concentrations of sulfate and heavy metals.

Phycobiliproteins production and heavy metals reduction ability of Porphyridium sp

Porphyridium sp is a unicellular red microalgae from Rhodophyta class which produces several high value polymers like polysaccharides, polyunsaturated fatty acids and phycobiliproteins. The phycobiliproteins contents are phycoerythrins, phycocyanins, and allophycocyanins. Porphyridium sp has the ability to reduce heavy metals pollution in the environment. This research was conducted in order to find out the potential use of Porphyridium sp for phycobiliproteins production and its ability in reducing the heavy metals Fe3+ and Co2+ in culture media. In this research, Porphyridium sp was cultivated in F2 non-silicate medium. The growth curve of Porphyridium sp was analyzed by cultivation at room temperature for 7 days and the OD 690 was monitored every day. Phycobiliproteins production was evaluated by analyzing the absorbance of the extracts at the wavelengths of 565, 620, and 650 nm. The ability of Porphyridium sp in the reduction of heavy metals Fe3+ and Co2+ was analyzed by AAS and calculated as bioconcentration factor (BCF). The data showed that the growth of Porphyridium sp in the media containing heavy metals Fe3+ and Co2+ was faster than in the control. The highest content of phycoerythrins, phycocyanins, and allophycocyanins of Porphyridium sp was reached after 4 days of cultivation with the addition of Fe3+ at 6.30 ppm. Porphyridium sp reduced Fe3+ and Co2+ in media with BCF values of 10.5804 and 0.1151, respectively.

Transcriptome analysis of silver, palladium, and selenium stresses in Pantoea sp. IMH

Heavy metal contamination is a significant environmental issue. Using bacteria for removal and reduction of heavy metals is an attractive alternative owing to its low-cost and eco-friendly properties. However, the mechanisms of resistance to and reduction of Ag(I), Pd(II), and Se(IV), especially in the same strain, remain unclear. Here, Pantoea sp. IMH was examed for its reduction of Ag(I), Pd(II), and Se(IV) to nanoparticles (NPs), and the molecular mechanism was investigated by transcriptome analysis. The results revealed that genes encoding binding, transport, catalytic activity, and metabolism were differentially expressed in cells exposed to Ag(I), Pd(II), and Se(IV). The same resistance mechanisms for all metals included multiple stress resistance protein BhsA and glutathione detoxification metabolism. However, zinc transport protein and sulfate metabolism played an important role in the resistance to cationic metals (Ag+ and Pd2+), while the oxalate transporter and arsenic resistance mechanisms were specifically involved in the resistance to and reduction of anion (SeO32−). In addition, Ag(I) was speculated to be reduced to AgNPs by glucose and cytochrome CpxP was involved in Pd(II) reduction. Our results provided new clues on the mechanisms of resistance to and reduction of Ag(I), Pd(II), and Se(IV).

Natural Triterpenoid-Tailored Phosphate: In Situ Reduction of Heavy Metals Spontaneously to Generate Electrochemical Hybrid Gels.

In this work, we reported a biocompatible nature product-based soft material which could convert heavy metals to nanoparticles (NPs) in situ spontaneously in a simple step. We have designed and synthesized a natural triterpenoid-tailored phosphate (methyl glycyrrhetate phosphate (MGP)), and this amphiphilic MGP could form the stable hydrogel and extract gold salt from water, followed by spontaneous in situ AuNP formation without external reductants. Notably, the AuNPs were mainly localized on nanofibers instead of gel cavities, and the resulting MGP-AuNPs hybrid gel exhibited attractive electrocatalytic and conductive properties. In addition, as an efficient leaching extraction agent, MGP hydrogel showed higher affinity toward heavy metals over other common metals on account of the high reduction potential of heavy metals. Our work not only provides a novel yet simple way in generating electrochemical hybrid gels by in situ reduction of heavy metals spontaneously but also expands the application of nature product-based functional materials.

Synergetic removal of Pb(II) and dibutyl phthalate mixed pollutants on Bi2O3-TiO2 composite photocatalyst under visible light

A highly efficient Bi2O3-TiO2 composite, prepared by a facile hydrothermal method, can be used for the removal of heavy metal Pb(II) and refractory organic dibutyl phthalate (DBP) from wastewater under visible light irradiation. The photo-induced electrons and holes separately transfer to different locations on the composite, resulting in different photocatalytic reaction sites for the refractory organic oxidation and the heavy metal reduction. This separation in space, thereby greatly improves the photocatalytic efficiency of both reactions. The energy level adjustment caused by Fermi levels matching at the n–p heterojunction, resulted in the Pb(II) being reduced to Pb(0) on the Bi2O3-TiO2 composite in visible light in both the Pb(II)-only and Pb(II)-DBP mixed systems. In contrast, no reduction was observed in visible light using only a Bi2O3 or TiO2 catalyst. Furthermore, the presence of refractory organic DBP in the system significantly increased the removal of Pb(II) while the presence of the more easily degradable phenol increased it to a lesser extent. These results indicate that coupling the reduction rate of heavy metals and the oxidation rate of organics can efficiently enhance the photocatalytic activity of the entire system.

Influence of the use of EM preparations on the content of heavy metals in the soil

The effect of microbiological preparations Baikal EM-1, Emochky-fertility, Orhanik-balance, Vermisol, Tseliulad, Biofosforyn on reduction of heavy metals (lead, cadmium, copper and zinc) concentration in soil. The coefficient of technogenic concentration of heavy metals in the soil for the use of EM preparations has been calculated. The prospect of using technologies of effective microorganisms for reducing soil pollution by heavy metals has been substantiated.

English

The present study investigated the removal of toxic pollutants and reduction of heavy metals from tannery wastewater using Chlorella vulgaris. The physiochemical parameters like pH, electrical conductivity (EC), biological oxygen demand (BOD), chemical oxygen demand (COD), total solids (TS), total dissolved solids (TDS), chloride, total hardness (TH), bicarbonate, magnesium, ammoniacal nitrogen, phosphate and heavy metals (Cu, Cr, Zn, Ni and Fe) were analysed using standard methods. Functional group of toxic chemicals in tannery wastewater and C. vulgaris treated wastewater were analysed by Fourier transforms infrared spectroscopy (FT-IR) and gas chromatography – mass spectrometry (GC-MS). 20 to 60% of chemicals (bicarbonate, chloride, nitrogen, phosphate and magnesium) were reduced by the treatment using C. vulgaris within 28 days. FT-IR and GC-MS analysis reveals that the functional group of azo compounds was not in C. vulgaris treated wastewater. Thus, the results obtained conclude that C. vulgaris can be used as a suitable tool for the removal of toxic chemicals of tannery wastewater. Key words: Chlorella vulgaris, toxic chemicals, tannery wastewater, physio-chemicals, Fourier Transforms Infrared Spectroscopy (FT-IR), Gas Chromatography – Mass Spectrometry (GC-MS).

Cr(VI) reduction and physiological toxicity are impacted by resource ratio in Desulfovibrio vulgaris

Desulfovibrio spp. are capable of heavy metal reduction and are well-studied systems for understanding metal fate and transport in anaerobic environments. Desulfovibrio vulgaris Hildenborough was grown under environmentally relevant conditions (i.e., temperature, nutrient limitation) to elucidate the impacts on Cr(VI) reduction on cellular physiology. Growth at 20 °C was slower than 30 °C and the presence of 50 μM Cr(VI) caused extended lag times for all conditions, but once growth resumed the growth rate was similar to that without Cr(VI). Cr(VI) reduction rates were greatly diminished at 20 °C for both 50 and 100 μM Cr(VI), particularly for the electron acceptor limited (EAL) condition in which Cr(VI) reduction was much slower, the growth lag much longer (200 h), and viability decreased compared to balanced (BAL) and electron donor limited (EDL) conditions. When sulfate levels were increased in the presence of Cr(VI), cellular responses improved via a shorter lag time to growth. Similar results were observed between the different resource (donor/acceptor) ratio conditions when the sulfate levels were normalized (10 mM), and these results indicated that resource ratio (donor/acceptor) impacted D. vulgaris response to Cr(VI) and not merely sulfate limitation. The results suggest that temperature and resource ratios greatly impacted the extent of Cr(VI) toxicity, Cr(VI) reduction, and the subsequent cellular health via Cr(VI) influx and overall metabolic rate. The results also emphasized the need to perform experiments at lower temperatures with nutrient limitation to make accurate predictions of heavy metal reduction rates as well as physiological states in the environment.

Preliminary study on heavy metal removal and turbidity reduction from groundwater by using apple pectin (bioflocculant)

Apple pectin, Malus pumila is used as an alternative flocculant in the water treatment of groundwater for removal of heavy metal (As, Cd, Cr, Fe and Pb) and turbidity reduction. There is 97.71% turbidity reduction achieved by using apple pectin with the optimum dosage of magnesium chloride, 15 mg/L at pH 10. From the heavy metal analysis, the results have shown that before treated with pectin, it has been found that all selected elements, As, Cd, Cr, Fe and Pb with concentration of 0.136 mg/L, 0.076 mg/L, 0.089 mg/L, 1.374 mg/L and 0.099 mg/L respectively exceed the standard. After the treatment conducted with apple pectin, only the concentration of Fe (0.107 mg/L) is accepted within the standard limit.

Preliminary study on heavy metal removal and turbidity reduction from groundwater by using apple pectin (bioflocculant)

Apple pectin, Malus pumila is used as an alternative flocculant in the water treatment of groundwater for removal of heavy metal (As, Cd, Cr, Fe and Pb) and turbidity reduction. There is 97.71% turbidity reduction achieved by using apple pectin with the optimum dosage of magnesium chloride, 15 mg/L at pH 10. From the heavy metal analysis, the results have shown that before treated with pectin, it has been found that all selected elements, As, Cd, Cr, Fe and Pb with concentration of 0.136 mg/L, 0.076 mg/L, 0.089 mg/L, 1.374 mg/L and 0.099 mg/L respectively exceed the standard. After the treatment conducted with apple pectin, only the concentration of Fe (0.107 mg/L) is accepted within the standard limit.

The Influence of Organic Matter Application Upon The Effectiveness of Reduction of Heavy Metals: Lead (Pb) and Cadmium (Cd) by Hyperaccumulator Plant

Organic matter is able to bind heavy metals. Soil enrichment with organic matter can reduce the availability of metal species as a result of the complexing of heavy metal free ions. This research examined the chelation of lead (Pb) and cadmium (Cd) waste-source heavy metals by organic matter, and the utilization of hyperaccumulator plants to remediate contaminated lands. The study was aimed to (a) analyze the influence of guano organic matter application to reduce heavy metals, Pb and Cd, and the combined effectiveness with plants; (b) to identify the capability of three plants as hyperaccumulator plants. Guano was used as an organic matter source in soils artificially contaminated with Cd and Pb from industrial solid waste. The research was conducted in two phases. The first research phaseused a combination of artificial Pb and Cd with guano. The second Research phase involved two dosages of guano and three concentrations of waste. Three plants were used as hyperaccumulator plants: elephant grass (Pennisetum purpureum), chinese cabbage (Amarantus tricolor), and water spinach (Ipomoea aquatica). The study results indicated that guano had the capability to chelate more than 90% of Pb and a maximum of 61% of Cd, hence reducing the concentration of Pb and Cd. Other results showed that the three hyperaccumulator plants generated different responses toward the addition of heavy metals (Pb and Cd). From the calculation of the Bio-Accumulation Factor (BAF), the value for Cd showed that P. Purpureum and A. Tricolor had good potential as hyperaccumulators. Only P purpureum had the capacity as a hyperaccumulator for Pb, while I.aquatica was not a hyperaccumulator plant for Cd or Pb. Keywords: heavy metals; hyperaccumulator; guano; bioaccumulation factor

Sediment core data reconstruct the management history and usage of a heavily modified urban lake in Berlin, Germany.

Urban surface waters face several stressors associated with industry and urban water management. Over much of the past century, the wastewater treatment in Berlin, Germany, relied on inefficient sewage farms, which resulted in severe eutrophication and sediment contamination in the recipient surface waterbodies. A prominent example is Lake Tegel, where a multitude of management measures were applied in the last decades for the purpose of ecosystem restoration. In this study, we analyzed sediment cores of three lakes with X-ray fluorescence spectroscopy: Lake Tegel, Lake Großer Wannsee, which is environmentally similar but has a different management history, and Lake Userin, which serves as a reference located in a nature protection area. Multivariate statistical methods (principal component analysis, k-means clustering, and self-organizing maps) were used to assess the sediment quality and to reconstruct the management history of Lake Tegel. Principal component analysis established two main gradients of sediment composition: heavy metals and lithogenic elements. The impact of the management measures was visualized in the lake sediment composition changing from high abundance of heavy metals and reducing redox conditions to less-impacted sediments in recent layers. The clustering techniques suggested heterogeneity among sites within Lake Tegel that probably reflect urban water management measures. The abundance of heavy metals in recent lake sediments of Lake Tegel is similar to a lake with low urban impact and is lower than in Lake Großer Wannsee suggesting that the management measures were successful in the reduction of heavy metals, which are still a threat for surface waters worldwide.

Reduction of heavy metal (Pb2+) biosorption in zebrafish model using alginic acid purified from Ecklonia cava and two of its synthetic derivatives

Heavy metal contamination has become a major problem that causes severe environmental and health issues due to their biosorption, bioaccumulation, and toxicity. This study was designed to evaluate heavy metal chelating abilities of alginic acid (AA) extracted from the brown seaweed Ecklonia cava and two of its derivatives prepared by the partial oxidation of the 2° OH groups (OAA) and partial carboxylation of the monomeric units (CAA) upon reducing the heavy metal biosorption in zebrafish (Danio rerio) modal. Metal ions were quantified using ICP-OES and biopolymers were characterized by FTIR and XRD analysis. All investigated biopolymers indicated potential ability for chelating Pb2+, Cu2+, Cd2+, As3+, and Ag+. The sorption capacities were in the order of CAA>OAA>AA. All biopolymers indicated a comparatively higher chelation towards Pb2+. AA, OAA, and CAA could effectively reduce Pb2+ induced toxicity and Pb2+ stress-induced ROS production in zebrafish embryos. Besides, they could reduce the biosorption of Pb2+ in adult zebrafish which could lead to bioaccumulation. Since alginic acid purified from E. cava and its derivatives could be utilized as seaweed derived biopolymers to purify heavy metals contaminated water and as a dietary supplement to reduce heavy metal biosorption in organisms.