Smelting Wastewater Research Articles

Evaluation of large-scale poultry manure-derived biochar for efficient cadmium removal in zinc smelter wastewater

Cadmium (Cd), a carcinogen, is released from industrial activities like metal refineries and battery runoff, with significant contamination reported near zinc smelters in Korea. This study addresses the issue using an efficient, economical adsorption process with waste-derived biochar-based adsorbents known for high Cd removal. Poultry manure (PM), typically used as fertilizer, can lead to environmental pollution if mismanaged; therefore, it was pyrolyzed to produce biochar. The resulting poultry manure biochar (PMBC) was produced on a large scale (15 ton/day), demonstrating feasibility for large-scale implementation. The effectiveness of PMBC as an adsorbent for Cd was evaluated using wastewater discharged from a zinc smelter. The Cd adsorption capacity of PMBC (60.39 mg/g) was lower than that (302.0 mg/g) of hen manure biochar produced at a laboratory scale in our previous study but was comparable to other biochars reported in the literature. Response surface methodology analysis indicated that reaction time, dose, and agitation significantly influenced Cd removal by PMBC, whereas pH had a negligible impact. Notable contributions to Cd adsorption include the release of K+ from PMBC and the presence of O-containing functional groups. Under continuous flow conditions with real wastewater, Cd was not detected in the effluent for the initial 8 h, and PMBC sustained a removal efficiency of 40.77% until saturation was reached. The results from wastewater treatment and large-scale biochar production offer valuable insights into the potential of biochar as a medium for addressing environmental issues in real-world applications.

Leaching behavior and kinetics of beryllium in beryllium-containing sludge (BCS)

Beryllium-containing sludge (BCS) is a byproduct of the physicochemical treatment of beryllium smelting wastewater. The pollutant element beryllium within BCS is highly unstable and extremely toxic, characterized by its small ionic radius and low charge density, resulting in a high risk of leaching and migration. This study is the first to investigate the leaching behavior, influencing mechanisms, and kinetic processes of beryllium in BCS under various environmental conditions. The results indicate that, under national standard conditions, beryllium exhibits a rapid leaching phase within the first 5 h, which then stabilizes after 10 h, with the total leached content significantly exceeding the leaching toxicity identification standards. Under mildly acidic (pH ≤ 5) or highly alkaline (pH = 14) conditions, beryllium demonstrates pronounced leaching and migration behaviors. Notably, in acidic conditions, the leaching rate exceeds 80% within 5 h. Combining the treatment process of beryllium-containing wastewater with analytical methods such as SEM, XPS, ToF-SIMS, and FTIR, it is revealed that due to the heterogeneous nature of BCS, the particle aggregates dissociate over time under acidic conditions. The particle surfaces become increasingly rough, leading to dissolution and the emergence of more reactive sites, resulting in a high proportion of beryllium leaching. Under these conditions, the gradual reaction of Be(OH)2 in BCS to form soluble Be2+ and its hydrolytic complexes is identified as the primary mechanism for extensive beryllium migration. The process encounters minimal diffusion resistance and is classified as reaction-controlled. In acidic conditions with pH = 4, the leaching rate of beryllium significantly increases with rising temperature. The leaching kinetics equation is [(1−x)−0.44]=e(18.26−53050RT)·t, with an apparent activation energy of 53.05 kJ mol−1.

Efficient cadmium removal from industrial wastewater generated from smelter using chemical precipitation and oxidation assistance.

The effective treatment of cadmium (Cd) in smelting wastewater is of great industrial importance. This study investigates the efficient removal of Cd from real industrial smelting wastewater via chemical precipitation using a series of experiments. In particular, the effects of different precipitants, agitation conditions, and the addition of NaOCl on Cd removal and pH variation are investigated. CaO (3.75 g/L), NaOH (3.50 g/L), and Ca(OH)2 (3.75 g/L) are found to be effective in elevating the wastewater pH and achieving high Cd removal rates (>99.9%), while the use of NaOH as a precipitant maintains a high Cd removal rate even at low agitation intensities. The properties of the produced sludge and supernatant are also determined using moisture content, particle size, and sludge leaching analyses due to the importance of economic and environmental sustainability in filtration, dewatering, and waste disposal processes. In addition, the addition of 2% NaOCl is tested, revealing that it can improve the Cd removal efficiency of Ca(OH)2, thus potentially reducing processing costs and enhancing the environmental benefits. Overall, these findings offer valuable insights into the removal of Cd from smelting wastewater, with potential implications for both environmental sustainability and economic viability. PRACTITIONER POINTS: CaO, NaOH, and Ca(OH)2 effectively remove Cd (>99.9%) from smelting wastewater. The use of NaOH leads to high Cd removal rates even at low agitation speeds. Adding 2% NaOCl can reduce the Ca(OH)2 dose for more economical Cd removal.

Correction: Insight into mineralizer modified and tailored scorodite crystal characteristics and leachability for arsenic-rich smelter wastewater stabilization

Correction for ‘Insight into mineralizer modified and tailored scorodite crystal characteristics and leachability for arsenic-rich smelter wastewater stabilization’ by Yonggang Sun et al., RSC Adv., 2018, 8, 19560–19569, DOI: https://doi.org/10.1039/C8RA01721B.

Use of thermally activated Fenton sludge for Cd removal in zinc smelter wastewater: Mechanism and feasibility of Cd removal

Fenton sludge is a byproduct of the Fenton process that contains large amounts of Fe and Ca. Because of the secondary contamination generated during the disposal of this byproduct, ecofriendly treatment methods are needed. In this study, we used Fenton sludge to remove the Cd discharged from a zinc smelter factory, using thermal activation to enhance the Cd adsorption capacity. Among the various temperatures considered (300–900 °C), the Fenton sludge that was thermally activated at 900 °C (TA–FS–900) adsorbed the highest amount of Cd because of its high specific surface area and high Fe content. Cd was adsorbed onto TA–FS–900 via complexation with C–OH, C–COOH, FeO−, and FeOH and cation exchange with Ca2+. The maximum adsorption of TA–FS–900 was 260.2 mg/g, indicating that TA–FS–900 is an efficient adsorbent, comparable to those reported in the literature. The initial Cd concentration in the zinc smelter wastewater discharged was 105.7 mg/L, 98.4% of which was removed by applying TA–FS–900, suggesting the applicability of TA–FS–900 for real wastewater containing high concentrations of various cations and anions. The leaching of heavy metals from TA–FS–900 was within the EPA standard limits. We concluded that the environmental impact of Fenton sludge disposal can be reduced, and the use of Fenton sludge can add value to the treatment of industrial wastewater in terms of the circular economy and environment.

Characterizing the removal of Pb2+ and Zn2+ from an acidic smelting wastewater using electrocatalytic internal Fe0/C micro-electrolysis

The discharge of acid non-ferrous metal smelting wastewater has received unprecedented attention with increasing threat to ecosystems and human health. A combined process of electrocatalytic internal Fe0/C micro-electrolysis (ECIME) fluidized bed was developed at lab scale (2.0L) to investigate the co-removal performance, optimization conditions and reaction characteristics differences of Pb2+ and Zn2+ from acid smelting wastewater. The results of cyclic voltammogram (CV) and XPS reveal that Pb2+ and Zn2+ can be electrodeposited on the carbon microelectrodes surface in ECIME system, and the positive shift degree of the reductive peak potentials under cathodic polarized is positively correlated with the voltage intensity. Metal ions reaction flow direction of ECIME system and SEM, EDS, XPS characterizations indicated that the removal of Pb2+ and Zn2+ were mainly attribute to electroreduction deposition and in-situ iron polymer hydroxyl flocculation, and including four reaction processes of electroreduction on surface of external electrode, iron-carbon particles microelectrode, self-flocculation and secondary flocculation. But the removal of Pb2+ and Zn2+ show different dominant reaction path, Pb2+ removal mainly depended on the electroreduction deposition (64.11%), whereas Zn2+ dominated by iron-based flocculation (62.93%). Response surface optimization based on the average efficiency indicated that the co-removal of Pb2+ and Zn2+ mainly depended on polarization voltage, reaction time, initial pH and electrolyte concentration with optimal conditions of 11.0 V, 58.65 min, 5.0, and 0.08 mol/L, and its optimal average removal efficiency reached 98.52% (initial concentration 100 mg/L), and the residual concentrations were 0.081 mg/L and 1.890 mg/L, respectively. These findings provide insights and theoretical for developing electrochemical platform to realize heavy metal wastewater zero discharge.

Removal of arsenic from copper smelting wastewater using zinc slag to synthesize scorodite

Removal of arsenic from copper smelting wastewater using zinc slag to synthesize scorodite

Heterotrophic anodic denitrification coupled with cathodic metals recovery from on-site smelting wastewater with a bioelectrochemical system inoculated with mixed Castellaniella species

Although Castellaniella species are crucial for denitrification, there is no report on their capacity to carry out denitrification and anode respiration simultaneously in a bioelectrochemical system (BES). Herein, the ability of a mixed inoculum of electricigenic Castellaniella species to perform simultaneous denitrification and anode respiration coupled with cathodic metals recovery was investigated in a BES. Results showed that 500 mg/L NO3−-N significantly decreased power generation, whereas 100 and 250 mg/L NO3−-N had a lesser impact. The single-chamber MFCs (SCMFCs) fed with 100 and 250 mg/L NO3−-N concentrations achieved a removal efficiency higher than 90% in all cycles. In contrast, the removal efficiency in the SCMFCs declined dramatically at 500 mg/L NO3−-N, which might be attributable to decreased microbial viability as revealed by SEM and CLSM. EPS protein content and enzymatic activities of the biofilms decreased significantly at this concentration. Cyclic voltammetry results revealed that the 500 mg/L NO3−-N concentration decreased the redox activities of anodic biofilms, while electrochemical impedance spectroscopy showed that the internal resistance of the SCMFCs at this concentration increased significantly. In addition, BES inoculated with the Castellaniella species was able to simultaneously perform heterotrophic anodic denitrification and cathodic metals recovery from real wastewater. The BES attained Cu2+, Hg2+, Pb2+, and Zn2+ removal efficiencies of 99.86 ± 0.10%, 99.98 ± 0.014%, 99.98 ± 0.01%, and 99.17 ± 0.30%, respectively, from the real wastewater. Cu2+ was bio-electrochemically reduced to Cu0 and Cu2O, whereas Hg0 and HgO constituted the Hg species recovered via bioelectrochemical reduction and chemical deposition, respectively. Furthermore, Pb2+ and Zn2+ were bio-electrochemically reduced to Pb0 and Zn0, respectively. Over 89% of NO3−-N was removed from the BES anolyte during the recovery of the metals. This research reveals promising denitrifying exoelectrogens for enhanced power generation, NO3−-N removal, and heavy metals recovery in BES.

Removal of Cd2+ from zinc smelter wastewater using graphene oxide foam cross-linked with epichlorohydrin: comprehensive optimization, isotherms, kinetics, and real water column studies

Removal of Cd2+ from zinc smelter wastewater using epichlorohydrin-cross-linked chitosan-GO (EPCSGO).

Highly effective remediation of high arsenic-bearing wastewater using aluminum-containing waste residue

Wastewater from non-ferrous metal smelting is known as one of the most dangerous sources of arsenic (As) due to its high acidity and high arsenic content. Herein, we propose a new environmental protection process for the efficient purification and removal of arsenic from wastewater by the formation of an AlAsO4@silicate core-shell structure based on the characteristics of aluminum-containing waste residue (AWR). At room temperature, the investigation with AWR almost achieved 100% As removal efficiency from wastewater, reducing the arsenic concentration from 5500 mg/L to 52 μg/L. With Al/As molar ratio of 3.5, the structural properties of AWR provided good adsorption sites for arsenic adsorption, leading to the formation of arsenate and insoluble aluminum arsenate with As. As-containing AWR silicate shells were produced under alkaline conditions, resulting in an arsenic leaching concentration of 1.32 mg/L in the TCLP test. AWR, as an efficient As removal and fixation agent, shows great potential in the treatment of copper smelting wastewater, and is expected to achieve large-scale industrial As removal.

Phosphoric acid functionalized superhydrophilic and underwater superoleophobic UiO-66/polyester fabric composite membrane for efficient oil/water separation and Gd(III) recovery

Efficient treatment of complex rare earth (RE) smelting wastewater has drawn great attention due to its potential environmental toxicity and the high demand of RE in modern technologies. However, it is still a challenge to achieve the simultaneous recovering RE and separating oil from wastewater. This study makes the first attempt to fabricate a versatile membrane, namely H-UiO-66-PF2, by loading 2-hydroxyphosphono acetic acid functionalized UiO-66 on polyester fabric through one-pot reaction strategy, and reports for the first time the simultaneous separation of oil/water mixtures and recovery of Gd(III). The H-UiO-66-PF2 exhibits standout oil/water separation performance with water flux up to 126,300 L·m−2·h−1 and separation efficiency above 99.8 %. Besides, the maximum adsorption capacity of H-UiO-66-PF2 for Gd(III) is reached 156.5 mg/g, adsorption equilibrium time is within 60 min. Moreover, the H-UiO-66-PF2 possesses high stability and recyclability, even after 20 cycles, separation efficiency and flux are 98.9 % and 105,200 L·m−2·h−1, respectively. Most notably, in addition to the separation of oil/water emulsion, complete Gd(III) capture is achieved from wastewater through filtration process. Therefore, this work provides a new design strategy to fabricate the composite membrane with great prospects for sophisticated smelting wastewater cleanup.

Study on membrane pollution caused by rare earth waste water treatment by membrane electrolysis process

ABSTRACT The membrane electrolysis technology is one of the treatment technologies for REx(CO3)y (rare earth carbonate) wastewater treatment. However, because the wastewater contains a few rare earth elements, it is easy to cause membrane contamination due to rare earth deposition on the membrane surface during membrane electrolysis treatment. This paper investigates the causes of membrane contamination caused by rare earth elements and the cleaning treatment of membranes to understand the mechanism of membrane contamination and improve membrane service life. Formation and composition of membrane pollutant produced in electrolysis process was analyzed and SEM micro-morphology analysis was done to study membrane pollutant. With the assistance of composition analysis by EDX and XRD, the main content of the membrane pollutant was determined to be RE(OH)3 amorphous precipitate. The influence of pH value of the electrolyte, the types of rare earth elements inside the electrolyte and the temperature of electrolyte on the pollution to the membrane was studied by pollutant absorption on the membrane and the ion flux change on the membrane. It was discovered that the adsorptive membrane pollution caused by Ce, Tb, and Y was relatively serious than other rare earth elements among the 16 rare earth elements, which concluded that the distribution of yttrium was higher in the heavy rare earth ore and the membrane pollution was severe when treating the smelting waste water of RE x (CO3) y produced by heavy rare earth ore by membrane electrolysis than by light rare earth ore. It was found that the mixed cleaning agent of HCl-NaClO had a good cleaning effect. The most considerable ion flux of the ion membrane after cleaning recovered to 96.5%. This study is expected to provide a valuable reference for the treatment of rare earth wastewater by membrane electrolysis.

As(III)‐to‐As(V) Oxidation in Copper Smelter Wastewater by In Situ‐Generated Ozone

AbstractAs(III) is the most common arsenic species in copper smelter wastewater but is difficult to remove, and an oxidation to As(V) is desirable. The oxidation of As(III) to As(V) in copper smelter wastewater was studied using in situ‐generated ozone, which has a high oxidation capacity and does not create secondary contaminants. With the aim to determine adequate conditions for As(III) oxidation, experiments considering pH, ozonation time, and oxygen flow rate as variables were done. Experimental tests showed that the best pH was at 2 and with a moderate oxygen flow rate. The complete oxidation of As(III) in both synthetic wastewater and real wastewater was achieved nearly after the same time of ozonation. Pseudo‐first‐order kinetics could model the As(III)‐to‐As(V) oxidation by ozone.

Effective R Emoval of Chlorine Ion from Copper Smelting Wastewater by N235 Extraction and Mechanism Analysis

Effective R Emoval of Chlorine Ion from Copper Smelting Wastewater by N235 Extraction and Mechanism Analysis

Green and circular method for chloride separation from acid wastewater: Application in zinc smelter

• A circular dechlorination process was proposed. • Dechlorination rate of bismuth absorbing materials exceeded 90%. • The elution rate of the dechlorination residue reached 93.64%. • Bismuth antichlor exhibits excellent cyclic performance. • Chlorine in the wastewater was converted to sodium chloride eventually. A circular method for dechlorination of acid wastewater and application in a zinc smelter was proposed based on thermodynamic calculations, where bismuth oxide was used as the dechlorination agent, and the entire process comprised bismuth oxide acidification–adsorptive dechlorination – alkaline washing – regeneration. First, bismuth oxide (Bi 2 O 3 ) was converted to clusters of rod-like bismuth sulfate or basic bismuth sulfate by sulfuric acid maturation, after which Clin the acid solution was adsorbed and formed a BiOCl precipitate. The rate of Clremoval from the zinc smelter wastewater reached more than 90% under the following optimum conditions: initial pH of 1.5, reaction temperature of 40 °C, 10-fold concentration of bismuth relative to the amount of Cl and reaction time of 1 h. BiOCl was then subjected to alkaline washing for dechlorination and regeneration of Bi 2 O 3 . The morphology of the dechlorination residue was rod-like, and a high concentration of NaCl solution was obtained at a temperature of 90 °C, reaction time of 1 h, NaOH concentration of 80 g/L, and liquid–solid ratio of 5:1, where the chlorine elution rate reached 93.64%. Finally, the bismuth oxide was acidified again with sulfuric acid and again dechlorinated. Tests showed that the dechlorination rate of regenerated bismuth oxide was still over 90% after 10 cycles. The process actually consumes only cheap sodium hydroxide due to the reuse of bismuth oxide, thus reducing the production costs and has potential industrial application given its simplicity.

FeOOH and nZVI combined with superconducting high gradient magnetic separation for the remediation of high-arsenic metallurgical wastewater

Metallurgical wastewater with high arsenic (As) concentration presents important challenges to human health and the environment because of its high toxicity and carcinogenicity. Iron (Fe)-based adsorbents can effectively detoxify low As-containing wastewater but are less helpful for high concentration of As and for solid–liquid separation. Herein, an advanced strategy is proposed to dispose high As wastewater using nano-zerovalent iron (nZVI) and ferric oxyhydroxide (FeOOH) combined with superconducting high gradient magnetic separation (HGMS) technology. The superconducting HGMS technology promoted the removal of As by nZVI and FeOOH via a magnetic flocculation reaction, while simultaneously separating reaction products adsorbed As from wastewater. Interestingly, nZVI could be corroded to release Fe(II) ions which then generated Fenton reaction under aerobic conditions, facilitating the oxidization of As(III)/Fe(II) to As(V)/Fe(III) ions. The Fe(II) and Fe(III) hydrolyzed in the form of hydroxy hydroxide and further generated the magnetic flocculates and coprecipitate. The results showed that 99.06% of As was successfully removed from wastewater with an initial As concentration of 5358 mg/L, at a dosage of 20 g/L, a magnetic field strength of 5 T, and a flow velocity of 500 mL/min. Compared with FeOOH, nZVI showed more favorable adaptability for lead smelting wastewater. Removal of As from wastewater by using nZVI combined with superconducting HGMS technology has a great potential to achieve industrial application for metallurgical heavy metal wastewater.

Ultra low-cost and bio-sustainable carbonized green algae for wastewater purification in gold smelting industry.

As a promising solar energy conversion technology, solar water evaporation has been regarded as an energy-efficient approach to alleviate the freshwater shortage caused by industrial water pollution. In this paper, we developed a straightforward method with a solar-driven steam generator (SSG) based on the carbonized green algae (CGA) as a light-to-heat conversion material (LHCM) to deal with the industrial wastewater of gold smelting. CGA SSG exhibited excellent light absorption, hydrophilicity, and water evaporation rate (1.66 kg·m-2·h-1). It accomplished the non-selective removal of heavy metal ions (Cu2+, Pb2+, Zn2+, Hg2+) and CN- in the treatment of gold smelting wastewater, and the ion removal rate was 99%. Compared with traditional and complex wastewater treatment technologies, the solar-driven CGA SSG presented many advantages (low cost, simple preparation, and high performance) in water purification, which could be employed in backward areas to obtain clean water.

Removal of cyanide from alumina smelter wastewater using precipitation and filtration technique

Aluminum is a metal that is used in many products because of its good conducting properties. However, in the production process, aluminum is not obtained easily but through a long process. In aluminum smelting process, wastewater that is produced indicates the existence of pollutants as determined by several indicators of water pollution, one of which is cyanide that will threaten human and environmental health if not treated properly. This study was conducted to determine the optimal dose of ferrous sulfate to remove cyanide, the precipitation and filtration process efficiency in reducing cyanide, and its effect on pH of wastewater. Data were collected from an aluminum smelting company, and experiments were conducted in the laboratory. Based on results, ferrous sulfate dose of 93 mg/l is the most optimal dose in removing cyanide with an efficiency of 58.74±0.51%, while filtration process provides an efficiency of 81.65±0.42%. Precipitation with ferrous sulfate makes pH value of wastewater decrease, but filtration process increases the value again. Throughout the whole process, cyanide can be reduced by a combination of precipitation and filtration process with the efficiency of 92.43±0.26% and an average final effluent concentration of 0.78 mg/L from an initial concentration of 10.3 mg/L.

Separation and stabilization of arsenic in copper smelting wastewater by zinc slag

Copper smelting wastewater shows strong acidity, has a high arsenic concentration and has many types of heavy metals, which not only restricts the sustainable development of copper smelting enterprises but also poses a danger to the ecological environment. Here, we propose a new process for treating copper smelting wastewater with zinc slag. We studied both the solid-liquid chemical reaction process as well as the mechanism by which zinc slag removes arsenic in copper smelting wastewater in a water bath at 85 °C under atmospheric pressure. Specifically, 5 g of zinc slag reacted with copper smelting wastewater with an initial arsenic concentration of 6000 mg/L for 4 h resulted in an arsenic removal rate of 99.65%, and the leaching concentration of arsenic in the toxicity characteristic leaching procedure experiment was only 0.52 mg/L. Zinc slag is dissolved in Copper smelting wastewater to release iron ions and silicate. The solid-liquid reaction of the two is accompanied by coprecipitation of iron arsenate and the in-situ covering of silica gel, resulting in a core-shell precipitate with iron arsenate as the core and silica gel as the shell. The colloidal chemistry of silica gel and cations and its chemical stability can effectively prevent the dissolution of arsenic ions and significantly improve the stability of iron arsenate. Zinc slag, a dual functional material for removing arsenic and fixing arsenic, shows extraordinary potential for the removal and fixation of arsenic in copper smelting wastewater. This approach could further improve wastewater treatment in the non-ferrous smelting industry.

PH-dependent photochemical transformation of arsenic sulfide sludge catalyzed by Fe ions under visible light irradiation

Arsenic sulfide sludge (ASS) is a typical precipitation product of acid smelting wastewater. Previous study reported that when exposed to sunlight, the release and oxidation of As(III) in ASS were markedly accelerated. However, the key factor to trigger the photocatalytic transformation of ASS is still unclear. Herein, we revealed that the coexisting Fe(II)/Fe(III) ions were critical to promote the photo-oxidation of released As(III) under visible light. We further validated that Fe(II)-stimulated photo-oxidation mechanism of As(III) in ASS was pH-dependent. In acid conditions, OH and SO4− were promoted by Fe(II)/Fe(III) cycling catalysis with the assistance of the reductive sulfur species from ASS, e.g. S2− and SO32−, and thus accelerated the oxidation of As(III). While in neutral conditions, the nascent ferric hydroxide colloids enhanced the oxidation rate of As(III) via photo-induced ligand-to-metal-charge transfer (LMCT) mechanism. These findings help in predicting and controlling the fate of real arsenic-containing sludge in sunlit environments.