Metals In Effluents Research Articles

Enhanced MFC sensor performances and extracellular electron transport efficiency mediated by biochar and underlying biochemical mechanisms

To explore the application of biosensor in real-time monitoring of composite heavy metal polluted wastewater in view of the low performance of MFC sensor, this study used sodium alginate to immobilize biochar to the anode of MFC biosensor, and conducted a study on the sensor performance and related biological processes. The results showed that under the optimal HRT conditions, the output power of the MFC-sensor (BC-300) was 0.432 W/m3 after biochar modification, which was much higher than the highest power density of CG and BC-0 of 0.117 and 0.088 W/m3. The correlation coefficient was greater than that of the control group at the plating wastewater concentration of 0.1–1.0 M and had a wider detection range, and the time to recover the output voltage was 1/3 of that of the control group. The biochar significantly promoted the sensitivity, interference resistance, recovery and anti-interference performance of the MFC-sensor. The intrinsic mechanism was that the composition and structure of biochar lead to a 1.53 fold increase in the abundance of electrogenic microorganisms and the abundance of functional genes such as cytochrome c (MtrABC, CymA, Cox, etc.) and flavin (riba, Rib B, gdh, ushA, IDH, etc.) increased by about 1.03–3.20 times, which promoted the shift of electrons from intracellular to extracellular receptors and significantly improved the electron transfer and the energy metabolism efficiency. The results of this study can provide a reference for the application of MFCsensor to the detection of complex heavy metal effluents.

Effects of root exudates of Vetiver on physicochemical properties and fractionation of heavy metals in tannery effluent contaminated soil

A range of organic substances, referred to as root exudates can be released by plant roots either actively or passively which are the notable source for microbial growth in the root zone and also involved in nutrient cycling and mineralisation of organics thus they could possibly influence the degradation of contaminants in the rhizosphere. The key components of the root exudates of vetiver are total carbohydrates, reducing sugars, total phenolics, flavonoids, total alkaloids, organic acids and total proteins. The organic acids are found in significantly higher amount under heavy metal stress conditions. On addition of this root exudates manually for a period of 60 days yielded in alteration in the physico-chemical properties of the soil and fractionation of chromium and lead – the representative contamiants present in the experimental soil which was collected from the tannery effluent polluted areas of Vellore, Tamil Nadu. The pH and organic carbon content in the soil is increased while the electrical conductivity got decreased. The root exudates application possibly increased the bioavailability of the heavy metals besides reducing the residual form which paves the way for easier remediation of such metals since their availability got increased. The positive effect of root exudates of vetiver provided a new idea to remediate the contaminated soils.

High efficiency removal of heavy metals and organic pollutants from brassware using raw coal: Kinetic adsorption and optimized process

This paper investigates the efficiency in organic matter and heavy metals removal from a synthetic brassware effluent using a natural adsorbent applied for the first time. raw coal used in continuous adsorption experiments was collected from the Jrada region (Morocco). Several analytical methods were adopted to evaluate material adsorption properties before and after the treatment of the effluent, including Scanning Electron Microscopy, Energy-Dispersive X-ray, X-ray Diffraction and Fourier Transform Infrared Spectroscopy. During the experimental part of this study, the adsorption kinetics carried to evaluate the performance of the test column has been investigated with optimization of operating parameters namely granular size, flow rate and column height. Finally, the selected parameters were used to evaluate the Chemical Oxygen Demand (COD) removal abilities. The results obtained show that the fixed column using a granulometry of 40 µm, a flow rate of 3 mL/min and a bed height of 18 cm provides a competitive performance, against both, organic matter and heavy metals. And the removal rates reached are 86 % of COD, 69 % of sulfate and 100 % of the most dominant heavy metals in brassware effluent; particularly Nickel, Silver and Copper.

A circular approach for the treatment of aqueous metal effluent and biomass to generate superparamagnetic nanometal carbon hybrid and hydrogen-rich gas mixture

In this study, simulated water effluent of transition metals (Ni, Zn, Fe, and Cu) and pine needles were integrated and treated hydrothermally for the generation of hydrogen and superparamagnetic carbon hybrid of metal/metal oxides of nano-size in a single-step. The temperature plays a significant role and decides the product yield and the same was varied (300-600 °C) to optimize the product yield. The highest yield of hydrogen was obtained with nickel metal effluent, 17.2 mmol. gram−1 of pine needles at 600 °C followed by other metals i.e., Fe(11.3 mmol.gram−1), Cu (10.64 mmol.gram−1), and Zn (8.86 mmol.gram−1) and greater than 99 % of the heavy metals (HMs) has been recovered from effluents (Ni, Zn, Fe, and Cu) in the form of nanometal carbon hybrid. The synthesized nanometal carbon hybrids were analyzed with the help of X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS), which shows that the metals present in the effluent get transferred to the lignocellulosic matrix of biomass during the supercritical water gasification (SCWG) that eventually gets reduced to pure metal (M(o)) from metal oxide (M(+n)). Metal oxide reduction results in the release of active oxygen, which promote the decomposition of the organics of biomass. Furthermore, the in-situ generated pure metal (M(o)) catalyzes the steam reforming and water gas shift reaction (WGS). Moreover, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and vibrating sample magnetometer (VSM) indicate that synthesized nanometal carbon nanometal hybrid was quasi-spherical or cubical has a size less than <30 nm and are superparamagnetic material.

PH-responsive nonwoven fabric with reversibly wettability for controllable oil-water separation and heavy metal removal

Removal of organic solvents and heavy metals in effluents is of great significance to environmental pollution control and ecological civilization construction. pH-responsive materials have unique advantages in treating complicated oily wastewater. In this work, an intelligent pH-responsive nonwoven fabric with excellent reversible wettability was prepared. The pH-sensitive polymer was synthesized by free radical polymerization (FRP) technique, then dipped with SiO2 on PP fabric. The particular molecular structure of poly (dimethylaminoethyl methacrylate) (PDMAEMA) enabled the fabric surface to switch wettability rapidly between hydrophilic/underwater oleophobic and oleophobic/hydrophobic under pH stimulus and exhibit controllable selective separation of various oil/water mixtures. Furthermore, the fabric removed Pb2+ efficiently under a wide pH range. The experimetal results showed that the separation flux reached 19,229 ± 1656.43 L-h−1-m−2 for water and 19,342 ± 1796.77 L-m−2-h−1 for n-hexane. Besides, the obtained fabric effectively realized the separation and collection process of complex ternary mixtures. The fabric removed Pb2+ in solutions with efficiency up to 90.83%. After immersing in acid and alkali solutions for 24 h, no significant damage to the surface wettability. This economical and intelligent fabric is able to meet the different separation purposes of industrial wastewaters with complex compositions.

Experimental evaluation of vertical metal retardation in stormwater management practices as influenced by cycles of baseline and high salinity

The application of NaCl as a deicer increases salinity of stormwater runoff, which may impact the speciation and mobility of various contaminants, including metals. Salt can remain in the fill media of stormwater management practices for an extended period after application, creating annual cycles of baseline and high salinity. This study evaluated the impacts of NaCl concentration and application cycles on metal retardation in fill media via 1-D continuous flow bench-scale columns. The high salinity scenario of 0.1 M NaCl decreased retardation factors of metals when compared to baseline salinity scenario of 0.01 M NaCl. Application of cycling baseline and high NaCl caused substantial fluctuations in the effluent metal concentration. The metals that were adsorbed during the baseline salinity periods were desorbed during the high salinity periods, leading to elevated concentrations of metals in porewater and effluent. Flushing with water removed only Na from the fill media top layers, while applying cysteine, as an environmentally friendly chelator, was demonstrated to be a promising approach to mobilizing accumulated metals from top layers to deeper layers. The results suggest that incorporating seasonal changes in environmental variables such as salinity enhances accuracy of contaminant transport modeling in fill media.

Isolation, Characterization and Heavy Metals Tolerance Indices of Indigenous Fungal Flora from a Tannery located at Challawa Industrial Estate of Kano State, Nigeria

Seven fungal species (Aspergillus niger, Aspergillus versicolor, Aspergillus flavus, Aspergillus fumigatus, Rhizomucor pusillus, Trichophyton equinum and Rhizopus oryzae) were isolated from the tannery effluent collected at a tannery industry located at Challawa industrial estate of Kano State, Nigeria. Aspergillus niger had the highest percentage occurrence frequency of 36% (31) while Trichophyton equinum had the least percentage occurrence frequency of 4% (5). Consequently, Aspergillus niger recorded the highest mean tolerance indices of 1.175, 0.830, 0.580, 0.780 and 0.630 while Rhizomucor pusillus had the least of the tolerance indices of 0.675, 0.375, 0.346, 0.450 and 0.255 for chromium, cadmium, manganese and lead respectively. Accordingly, furthermore the minimum inhibitory concentration (MIC) and biomass yield of the seven tested fungi isolates cultured in the presence of the five heavy metals used in this study showed different level of growth pattern. Hence the high resistant potentials and tolerance to the selected heavy metals exhibited by the fungal species isolated in this study is an indication that indigenous fungal floral isolated from tannery effluent if properly harnessed may offer a feasible solution to the serious environmental pollution problems associated with the presence of heavy metals in tannery effluent.

Adsorptive removal of Cu(II) by fly ash based geopolymer material

Geopolymer are aluminosilicate inorganic polymer synthesized by polymerization of aluminosilicate with alkaline solutions. These materials possess high surface area hence promising adsorbent. In this paper fly ash and rice husk-based geopolymer type hybrid mass is applied for remediation of Cu(II) ions. Various adsorptive parameters for example contact /reaction time, effluent metal ions concentration, dose of hybrid mass, pH and operating temperature are optimized and fixed for getting maximum removal of aqueous Cu(II) ions. Equilibrium isotherm and kinetic studies revealed that the isotherm data were best described by Langmuir adsorption isotherm and the rate of adsorption follows the pseudo second-order. Thermodynamic studies carried out by applying Van’t Hoff equation, which revealed that the process was exothermic and spontaneous. Results indicate encouraging performance of hybrid mass towards removal of Cu(II) ions.

Physicochemical characterization and heavy metals analysis from industrial discharges in Upper Awash River Basin, Ethiopia

The recent expansion of industries in Addis Ababa is causing additional environmental pollution through wastewater discharges; this is becoming a critical concern. Addis Ababa is located in the upper Awash River basin, and is the main source of industrial pollutants to the river. In this study, physicochemical parameters, nutrients and heavy metal content of wastewaters released from 16 factories, 6 tanneries, 6 beverages and 4 diverse factories, and the Akaki-Kality central wastewater treatment plant in Addis Ababa, were sampled to assess the level of pollutants. Heavy metals were determined using inductively coupled plasma optical emission spectroscopy (ICP-OES). Analysis of nutrients were conducted using Palintest Photometer. Physicochemical characteristics were measured either in situ using a portable micro meter or in the laboratory. Among the measured physicochemical properties, critical issues were observed with electrical conductivity, total dissolved solids and total hardness. Effluents from all of the tanneries, and a number of other factories, were found at levels higher than the maximum limits of various guideline standards. In addition, samples from two of the tanneries (T1 and T5), two beverage factories (B3 and B6) and the central wastewater treatment plant showed elevated concentrations of PO4 3-, which violated the limit (10mg/l) set by Environmental Protection Agency of Ethiopia (ETHEPA). The two tanneries (T1 and T5) also contained higher SO4 2- than the guideline limit of 1000mg/l. On the other hand, only one factory, one brewery (B3), exhibited NO3 - above the standard limit of 20mg/l. Whereas NH3, NH4 +, Cl-, S2- and NO2 - were within the limits in all of the samples. Severe pollution was found in wastewaters from tanneries, where half of them (T1, T5 and T6) contained Cr beyond the maximum limit of 2000µg/l. Furthermore, a third of the tanneries (T1 and T5) and a beverage factory (B5) contained Fe, Mn, Zn and Cu, higher than the ETHEPA limits of 10000, 5000, 5000 and 2000µg/l, respectively. Waste disposal from factories without proper treatment can cause great harm to the local people and the environment. Hence, the results of this study call for regulatory bodies to pay close attention to factories, particularly tanneries, in Addis Ababa in implementing adequate treatments of their wastewater discharges.

Bioremoval of Different Heavy Metals in Industrial Effluent by the Resistant Fungal Strain Aspergillus niger

Developing countries are increasingly concerned with pollution due to toxic heavy metals in the environment. Unlike most organic pollutants which can be destroyed, toxic metal ions released into the environment often persist indefinitely circulating and eventually accumulating throughout the food chain thus posing a serious threat to mankind. The use of biological materials for heavy metal removal or recovery has gained importance in recent years due to their good performance and low cost. Among the various sources, both live and inactivated biomass of organisms exhibits interesting metal binding capacities. Their complex cell walls contain high content of functional groups like amino, amide, hydroxyl, carboxyl, and phosphate which have been implicated in metals binding. In the present study, Aspergillus niger was used to analyze the metal uptake from an aqueous solution. The determination of Cu+2, Pb+2, Cd+2, Zn+2, Co-2 and Ni+2 in samples was carried out by differential Pulse Anodic Voltammetry (DPASV) and the Voltammograms. Production of oxalic acid was carried out by submerged fermentation. The organism used in the present study has the ideal properties to sequester toxic metals and grow faster.

Assessment of significant metals in effluents, soil, and pond water of tanneries south of capital of Sudan state

In the present study, impact of tannery effluents and their subsequent on accumulation of some metals (Ca, K, Na, Mg, Cl, S, Cr, Fe, Mn, Pb, and Zn) in water and soil samples in and around South Khartoum industrial area, Khartoum-Sudan were studied. Concentration of metals in tannery effluents (SA), adjacent contaminated pond water (SB), Soil (SC), and uncontaminated water (SD) were assessed by atomic absorption photometer. The results showed high levels of Ca, K, Na, Mg, Cl, S, Cr, Fe, Mn, Pb, and Zn within the water from all sampling point (SA, SB and SC). The investigation exhibited that tanneries wastewater has high mean concentrations of Cr, Fe, Mn, and Pb in all sampling point of effluent, pond water, soil, and uncontaminated water, except Zn which is high only in soil sampling point (SC). The significant metals accumulation displayed a pattern of mean concentration as follow: Soil &gt; Effluent &gt;contaminated pond water &gt; Un contaminated water. Significant metals toxicity levels within the totally different sampling points were compared with water from WHO. Mean metal concentrations in un contaminated water were among the allowable limit set by WHO except for Magnesium (Mg). The comparison indicated that soil (SC) within the neighboring industrial area accumulated metals, enhanced levels of toxic of metals such as Cr, Ni, Zn and Pb, which also demonstrated higher concentration levels in the adjacent contaminated pond water samples. increased levels of poisonous, that additionally incontestable higher concentration levels within the contaminated pond water.

Assessment of significant metals in effluents, soil, and pond water of tanneries south of capital of Sudan state

Assessment of significant metals in effluents, soil, and pond water of tanneries south of capital of Sudan state

New challenges and applications of supported liquid membrane systems based on facilitated transport in liquid phase separations of metallic species

The linear economic model based on “take-make-dispose” has become unsustainable, revealing the necessity of shifting towards a circular economy approach, in which secondary raw materials play a key role in closing material cycles. In this context, industrial effluents with metallic content, are considered a potential secondary source for these elements, the lack of the availability of the appropriate technology being the main barrier when implementing circular economy principles at industrial scale. In this regard, supported liquid membrane systems based on facilitated transport may be decisive. Thus, the objective of this research paper is to show the potential of facilitated transport systems to foster the transition to a more sustainable management of industrial metallic effluents. To accomplish that, three different applications of supported liquid membrane systems in acidic industrial effluents will be presented: a) Zn/Fe separation, b) Ni/Cd separations and c) Removal of hexavalent Cr. Additionally, the recovery and separation of two different critical raw materials, i.e. Li and rare earth elements will be discussed. Although facilitated transport systems have been successfully applied to both, Zn/Fe and Ni/Cd separation, as well as to hexavalent Cr removal, further work should be done for the successful recovery and separation of Li and rare earths with supported liquid membrane systems, especially in terms of selectivity improvement and validation with real industrial effluents.

First principle investigation of boron functionalized graphene to detect the presence of “arsenic” in water

Heavy metals in industrial effluents create severe water pollution, leading to adverse effects on human beings. Thus, to save mankind from the ill effects of these heavy metals and to monitor its’ concentration within the permissible limits, effective sensors are required to be marked in terms of sensitivity, selectivity, and simplicity. In this work, boron functionalized graphene (BG) has been examined for its sensing ability towards Arsenic (As) by analyzing its band structure, density of states, and current–voltage characteristics in both vacuum and aqueous environments. The findings of the vacuum environment reveal that the arsenic interacts strongly with BG sheet owing to its high binding energy −2.63eVthat results in an opening of a bandgap of ~0.206 eV, infers the sensing ability of the sheet towards arsenic. Further, to comprehend the effect of an aqueous environment on the sheet's sensitivity, calculations are carried out in the presence of water molecule. The findings show that the BG sheet can detect the As in water with a sensitivity of ~15% at a low applied voltage of 400 mV.

Heavy Metal Uptake of Leafy Vegetable Irrigated with Different Source of Industrial Effluents

The accumulation of heavy metals in vegetable and food crops irrigated by different industrial effluents is considered a consequential environmental problem in several countries such as Bangladesh, where wastewater is routinely used as a water source for irrigation of crop fields. The present investigation was conducted to assess the prevalence of different heavy metals like iron, manganese, zinc, copper, nickel, cadmium, chromium, and lead in Indian spinach irrigated with three different (pharmaceutical, beverage and dyeing) sources of industrial effluents. The results showed a considerable amount of heavy metals present in the effluent water and deposited in the soil after irrigation. The plant (root, stem and leaves) also accumulated the heavy metals from the contaminated soil. The range of different metals in effluent treated plant leaves was 177-294, 14.14-23.13, 19.15-33.99,7.53-12.49, 7.38-12.55, 0.98-1.17, 5.26-7.06, and 4.12-7.35 mg/kg for iron (Fe), manganese (Mn), zinc (Zn), copper (Cu), nickel (Ni), cadmium (Cd), chromium (Cr) and lead (Pb), respectively. The transfer factor from soil to other plant parts was highest in the root for all the three types of effluents and the transfer factor from root to other parts was more than 1 in case of copper (Cu) and nickel (Ni).

Heavy metals assay of herbal pharmaceutical effluent

Environmental pollution particularly from heavy metals in effluent is the gravest problem in developing countries like Pakistan. Effluents of Herbal Pharmaceutical are waste water generated during Herbal Medicines manufacturing process. When these effluents deprived of appropriate treatment are released directly into the environment, results in potential adverse effects on human health and the environment. This research work examined the heavy metals parameters of effluents discharged by Herbal pharmaceutical industry in Karachi, Pakistan. In all, 08 parameters were studied. These include Cr, Mn, Fe, Co, Ni, Cu, Ag and Pb. The study revealed that ranges of Ag and Fe were exceeding the allowable limit of WHO (World Health Organization) and NEQS (National Environmental Quality Standards). This calls for an immediate use of latest treatment plants to decrease the harmfulness that results from waste water.

Efficiency and Kinetic Rate of Nanoscale and Microscale of Zero Valent Iron and Zinc Oxide particles for Chromium, Cadmium, and Lead Removal from Pak Thong Chai Silk Dyeing Effluent, Thailand

This present study involved the application and comparison of nanoscale particles in remediation for contaminated heavy metal effluent discharge. It aimed to investigate the removal efficiency and kinetic removal rate of the heavy metals including lead, chromium, and cadmium in silk dyeing effluent discharge by using nano and microscale of ZVI and ZnO particles. The contaminated samples were collected and later treated by one of the particles in the laboratory at 25 oC. The mixtures were incubated for the required period before the heavy metal concentrations were measured. The overall results showed that the optimum dosage of all four particle types for heavy metal treatments was 60 mg/L with an optimal time of 60 minutes. The experiments with nZVI demonstrated the highest removal efficiency for all heavy metal types followed by that of nZnO, ZVI, and ZnO, respectively. The removal efficiency rate by all four type particles for Cr was higher than that of Cd and Pb, respectively. In addition to this, the kinetic removal rate of nZVI was also faster than that of nZnO, ZVI, and ZnO, respectively..

Production of H2S with a Novel Short-Process for the Removal of Heavy Metals in Acidic Effluents from Smelting Flue-Gas Scrubbing Systems.

Direct sulfidation using a high concentration of H2S (HC-H2S) has shown potential for heavy metals removal in various acidic effluents. However, the lack of a smooth method for producing HC-H2S is a critical challenge. Herein, a novel short-process hydrolysis method was developed for the on-site production of HC-H2S. Near-perfect 100% efficiency and selectivity were obtained via CS2 hydrolysis over the ZrO2-based catalyst. Meanwhile, no apparent residual sulfur/sulfate poisoning was detected, which guaranteed long-term operation. The coexistence of CO2 in the products had a negligible effect on the complete hydrolysis of CS2. H2S production followed a sequential hydrolysis pathway, with the reactions for CS2 adsorption and dissociation being the rate-determining steps. The energy balance indicated that HC-H2S production was a mildly exothermic reaction, and the heat energy could be maintained at self-balance with approximately 80% heat recovery. The batch sulfidation efficiencies for As(III), Hg(II), Pb(II), and Cd(II) removal were over 99.9%, following the solubilities (Ksp) of the corresponding metal sulfides. CO2 in the mixed gas produced by CS2 hydrolysis did not affect heavy metals sulfidation due to the presence of abundant H+. Finally, a pilot-scale experiment successfully demonstrated the practical effects. Therefore, this novel on-site HC-H2S production method adequately achieved heavy metals removal requirements in acidic effluents.

Production of biomass and exopolysaccharides obtained from Pleurotus hybrid strains under different pHs to remove heavy metals in aquaculture effluents.

Production of biomass and exopolysaccharides obtained from Pleurotus hybrid strains under different pHs to remove heavy metals in aquaculture effluents.

Diethylenetriamine as a selective pyrrhotite depressant: Properties, application, and mitigation strategies

AbstractPyrrhotite (Po) is an abundant iron sulphide mineral that occurs in nickel sulphide deposits, such as those in Sudbury, Ontario. Due to its low economic value and its high contribution to SO2 emissions produced during smelting, Po is rejected into the tailings during mineral processing. The rejection of Po can be accomplished in several ways, including by using chelating agents such as diethylenetriamine (DETA) as depressants in froth flotation. DETA can significantly improve nickel recovery and concentrate grades; however, it is challenging to manage in the tailings area. DETA, when used, forms stable chelates with Ni2+ and Cu2+ which cannot be precipitated with traditional lime treatment. Once in the tailings management area, DETA can desorb from Po solids upon dilution or with changes in temperature and/or pH. The species chelated with DETA can also change depending on the availability of the ions in solution. The use of DETA can, therefore, lead to concentrations of Ni2+ and Cu2+ in final effluent that exceed the regulated amounts. Due to the challenges with chelated metals in effluent, it is recommended that the chelating agents be removed from the tailings stream before it is deposited. Although DETA‐metal chelates are rarely discussed in the literature, some mitigation and degradation strategies investigated by industry are discussed in this review. DETA degradation methods are also discussed, with the primary focus being on biodegradation. DETA has generally been described as recalcitrant to biodegradation although there is evidence that proper acclimation should allow bacteria to develop DETA degradation pathways.