Acidic Wastewater Research Articles

Efficient As(III) removal from acidic wastewater by polymorphism control of FeS

Efficient As(III) removal from acidic wastewater by polymorphism control of FeS

BPPO-based anion exchange membranes for acid recovery via diffusion dialysis

Diffusion dialysis (DD) with anion exchange membranes (AEMs) as the core component is an ideal technology for acid recovery from acidic wastewater.

Removal mechanism of lead by the composite of clinoptilolite, biochar, and Ca(OH)2 and its application in acid wastewater

Removal mechanism of lead by the composite of clinoptilolite, biochar, and Ca(OH)2 and its application in acid wastewater

Heterogeneity in microbial fuel cell stacking influences acidogenic metabolism towards bioelectricity generation, fatty acid synthesis and wastewater treatment

This study explores the influence of varied stacking configurations in microbial fuel cells (MFCs) to channel acidogenic metabolism for enhanced bioelectricity generation, value-added acid synthesis, and wastewater treatment.

Recycling of acidic iron wastewater for production of iron oxalate anode material with superior long cycling lithium storage ability

Recycling of acidic iron wastewater for production of iron oxalate anode material with superior long cycling lithium storage ability

Recyclable phospho-enriched polyamidoxime/alginate gel beads for efffcient extraction of uranium(VI) from acidic mining wastewater

Recyclable phospho-enriched polyamidoxime/alginate gel beads for efffcient extraction of uranium(VI) from acidic mining wastewater

Design parameters for gypsum production from limestone and acidic wastewater of a copper processing plant

Design parameters for gypsum production from limestone and acidic wastewater of a copper processing plant

Removal, conversion and utilization technologies of alkali components in bayer red mud.

Bayer red mud is a highly alkaline industrial solid waste generated during alumina production, and its massive discharge and stockpiling poses significant environmental risks. The strong alkalinity of red mud is a primary challenge limiting its effective utilization. This study systematically analyzes the composition and characteristics of alkaline components in red mud, emphasizing the roles of soluble free alkali and chemically bound alkali in regulating its alkalinity. A comprehensive review of current dealkalization technologies, including acid neutralization, CO2 neutralization, and salt precipitation/replacement methods is presented, focusing on their chemical mechanisms, applicability, advantages, and limitations. Specially, this study present the concept of in-situ conversion and utilization of alkali and highlight the beneficial role of alkali components in red mud recycling. The latest technologies for the conversion and utilization of alkali components, including the special roles and principles of alkali in the reaction processes of cement clinker calcination, cement hydration, geopolymers were systematically summarized. Additionally, the environmental potential of red mud in acid wastewater neutralization and flue gas desulfurization is discussed. This study identifies the technical barriers that need to be solved urgently in the current research and proposes a key direction for future study on the regulation of alkali components in red mud.

Calculation Features of Vertical Settling Tanks for Heavy Metal - Containing Wastewater Treatment

The article discusses the treatment of wastewater containing heavy metal salts before releasing it into natural water bodies or the urban drainage system. The focus is on environmental protection, human health, and the potential for recovering valuable metals from wastewater. A vertical settling tank was selected for its cost-effectiveness in treating metal-containing acidic wastewater. The article provides a general method for calculating these settling tanks during reagent sedimentation, which can be used to remove various types of heavy metal salts. For this purpose, all calculations related to the use of reagents (their quantities, volumes of reagent storage, solution tanks, and neutralization chambers) were conducted in advance. Additionally, corresponding chemical equations for the reagents and various acids, as well as the equations for the reactions occurring between the reagents and heavy metal salts, were formulated.

Kinetics of manganese extraction from pyrolusite using reduction leaching of acidic wastewater from steel plants

ABSTRACT Acidic wastewater from steel works was selected to reduce pyrolusite. The effects of leaching parameters such as the ratio of FeCl2 to MnO2, leaching temperature, liquid–solid ratio and initial HCl concentration in acidic wastewater on the leaching rate of manganese were investigated. The results show that under the conditions including the molar ratio of FeCl2 and MnO2 ( m FeC l 2 / m Mn O 2 ) at 2.2, the leaching temperature of 363 K, a leaching time of 180 min, an L/S ratio of 11:1, and an initial HCl concentration in acidic wastewater of 2.5 mol/L, the leaching rate of manganese in pyrolusite was 97.14%. An unreacted shrinking core model was employed to explore the kinetics of manganese in pyrolusite arising from the reduction leaching of acidic wastewater from steel plants. The results imply that the rate-determining step changed in the leaching process; among which, the first stage (0–100 min) of leaching was subject to the control of interfacial chemical reactions; the second stage (100–180 min) was controlled by internal diffusion. The apparent activation energy of the two stages was 15.57 and 125.48 kJ/mol respectively, and the apparent rate equations were respectively: 1 – ( 1 – r ) 1 / 3 = 0.39 ( m FeC l 2 / m Mn O 2 ) 1.18 [ HCl ] 0.21 ( V L / M S ) 0.62 exp ( − 15.57 / RT ) t 1 – 3 [ ( 1 – r ) / ( 1 – r 1 ) ] 2 / 3 + 2 [ 1 – ( 1 – r 1 ) ( r – r 1 ) 1 / 3 ] = 2.22 × 10 16 ( m FeC l 2 / m Mn O 2 ) 5.81 [ HCl ] exp ( − 125.48 RT ) t

Mechanism study of the effect of copper ions on the stability of As(III) sulfuration precipitation in acidic copper smelting wastewater.

Sulfide precipitation is considered as a very efficient method for removing arsenic from actual copper smelting acidic wastewater. However, the arsenic removal process can be affected by copper ions. This study focuses on the mechanism of copper ions' influence on the stability of As(III) sulfuration precipitation. Sulfuration reaction experiments are carried out using Na2S in three different simulated highly acidic wastewaters with initial As(III) concentrations of 2000mg/L (LAs), 5000mg/L (MAs), and 10000mg/L (HAs), and the implications of processes variables of S/As ratio and copper concentration on the stability of As(III) sulfuration precipitation are discussed. The results show that the As(III) sulfuration precipitation is significantly affected by copper ions in the LAs reaction systems, whereas in the MAs and HAs reaction systems, which can be noticeably affected by copper ions only when the S/As is not greater than 1.5 (≤ 1.5), i.e., when the amount of Na2S is insufficient. Person correlation analysis also demonstrates a remarkable negative correlation (correlation coefficient is around - 0.96) between the S/As ratio and copper ion concentration on As(III) removal efficiency in the LAs reaction systems. The effect of copper ions on As2S3 is further investigated, and it is detected that copper ions cause approximately 3.3% of the precipitated As2S3 to be re-dissolved. This study proves that copper ions not only compete with As(III) for S2-, but also cause the precipitated As2S3 to re-dissolve. Therefore, in the actual manufacturing process, it is essential to control not only the sulfiding dose, but also the copper ions. This study provides a specific reference for actual enterprises to sulfurize As(III) from highly acidic wastewater and is of great significance for controlling actual industrial processes.

Utilization of Bottom Ash from Biomass Combustion in a Thermal Power Plant to Remove Cadmium from the Aqueous Matrix.

This study provides a cost-effective method for using bottom ash from biomass combustion, which would otherwise constitute waste, to remove cadmium from acidic industrial wastewater. The X-ray powder diffraction method was used to identify the crystal forms, i.e., the arrangement of atoms in the crystal lattice, and to determine the composition of bottom ash, and the X-ray fluorescence method was used to obtain information on the elemental composition of bottom ash. The Fourier Transform Infrared method was used to analyse and identify the different functional groups occurring in bottom ash. Scanning Electron Microscopy with energy-dispersive X-ray was used to obtain detailed information on the bottom ash surface. The effect of various factors on Cd removal was studied, and optimal experimental conditions were found. The kinetic and thermodynamic equations showed that the removal of Cd2+ using bottom ash from biomass combustion was a single-layer chemical adsorption meeting the requirements of pseudo-second-order kinetics. The limiting parameter for the effective adsorption of Cd2+ using bottom ash from biomass combustion is its alkaline nature. It can only be used for solutions with pH < 2, which, on the other hand, is its advantage in practical application, namely, in the final treatment of acidic industrial wastewater.

Advanced neutralization technique for the treatment of highly acidic wastewater from steel rolling mills of western Rajasthan.

In this study, we developed an economical treatment process for highly acidic effluents from steel rolling mills containing toxic heavy metals. Our method involves a pH-dependent approach using mining waste and hydrated lime. The treatment occurs in two steps: First, metal oxides precipitate at pH3-3.5 using mining waste, followed by lime precipitation at pH9-9.5. The process, completed in less than 6h without heavy machinery, reduces sludge formation by extracting high-purity gypsum, a valuable industrial product. Water quality posttreatment matches local groundwater standards. Compared to conventional methods like common effluent treatment plant (CETP) in Jodhpur, India, our approach reduces operational costs by over 58%. In this study, we also characterized the by-product formed, that is, gypsum using various characterization tools and performed a detailed cost analysis. PRACTITIONER POINTS: A quick, efficient, and economical treatment process for extremely acidic (pH ~ 1) wastewater from steel industries. Stepwise treatment strategy without involving heavy machinery or high manpower. Processed water quality closely resembles groundwater with all the major heavy metals been removed. Sludge quantity reduced by regeneration of pure gypsum (96% purity). Reduced the overall operation cost of effluent treatment by 58%.

Enhanced removal of Fe, Cu, Ni, Pb, and Zn from acid mine drainage using food waste compost and its mechanisms

Heavy metals (HMs) in acid mine drainage (AMD) pose serious threats to aquatic life and soil. Biosorbents are promising materials to remove HMs from wastewater. Herein, food waste compost was used as a low-cost and sustainable biosorbent to remove Fe3+, Cu2+, Ni2+, Pb2+, and Zn2+ from an AMD and other model solutions with an initial pH of 2.24. Batch adsorption tests were conducted to systematically investigate the influences of initial pH, compost dose, the presence of Fe3+ and SO42− ions, and the pH-induced Fe precipitates on the removal performance. The involved removal mechanisms were explored by conducting stepwise precipitation tests, sequential extraction tests, and Fourier transform infrared spectroscopy (FTIR) characterization. It was found that the addition of the compost removed over 90% of Zn, Ni, Cu, and Pb at pH 5.80, 5.50, 4.50, and 3.00, respectively. At low compost doses, the presence of Fe3+ and SO42− ions hindered the removal since the competition effect of Fe3+ ion and lower absorbability of metal-sulfate complexes, respectively. Sequential extraction tests revealed that higher fractions of Fe, Cu, and Pb were strongly immobilized through complexation and precipitation relative to Ni and Zn. Additionally, the pH-induced Fe precipitates did not favor the removal of the HMs, probably due to the adsorption of organic components released from the compost. This study suggests that compost have the potential to remove HMs from acidic wastewater without pre-neutralization.

Synergistic flocculation performance and underlying mechanisms of a novel bioflocculant flocan with coagulant iron salt

Flocculation is an integral part of wastewater treatment units and various flocculants have been employed to strengthen the flocs formation and produce clean water. Natural polysaccharides have been employed as eco-friendly bioflocculants for the treatment of turbid water. In the study, flocan is a named exopolysaccharide (EPS) isolated from a coastal mudflat with a high yield of 8.3g/L. Flocan consisted of glucose, mannose, galactose, and glucuronic acid in a molar ratio of 2:3:1:1, along with pyruvate modifications. As the bioflocculant agent, flocan exhibited more than 85% removal efficiency in kaolin suspension in terms of a concentration of 10mg/L at pH 3. The addition of iron salts with flocan showed high flocculation efficiency in acidic kaolin suspension (99.37%) and acidic coal wastewater (99.44%). The carboxyl/hydroxyl groups and branched structure of flocan provided ionic interactions and promoted higher bridging between bioflocculants and negatively charged particles. Coagulants FeCl3 enhanced the flocculating activity via neutralizing and stabilizing the residual negative charge of functional groups. Treatment with EDTA decreased the ionic interactions and reversed the flocculation significantly. Compared with the current bioflocculants, the superior production, low dosage, and excellent flocculating activity implied that flocan showed great potential in acidic wastewater treatment industrially. The coagulants/bioflocculants combination appears to be a promising and sustainable technology for wastewater flocculation.

Molybdenum recovery from acidic industrial wastewater using Bayesian optimization algorithm-based ANN model: A case study by applying chemical precipitation followed by solvent extraction

Molybdenum recovery from acidic industrial wastewater using Bayesian optimization algorithm-based ANN model: A case study by applying chemical precipitation followed by solvent extraction

Geochemical studies of potential acid-forming classification materials to reduce acid mine drainage formation

Abstract Acid mine drainage (AMD) is acidic wastewater produced in coal mining operations due to sulfide mineral oxidation. In compliance with the regulations of good mining practice procedures, each mining operation must conduct a geochemical study of the distribution of material classification categories to identify the potential acid-forming (PAF) or not acid-forming (NAF) materials to mitigate the AMD. This research conducted a field observation at one of the post-mining lakes of a coal mining operation in South Kalimantan. It determined materials or rocks that have the potential for acid formation using static tests with the Net Total Acid Producing Potential (NTAPP) method. The results of coring samples were processed to obtain rock lithology data for four drilling points, demonstrating one layer of low-capacity PAF material in borehole point A, one layer of low-capacity PAF material, and one layer of PAF material in borehole point B. Only one layer of PAF material was in borehole point C and borehole point D. These PAF/NAF data highlighted essential information about PAF/NAF, underscoring the significant role of our work in improving the strength and accuracy of mitigation plans and reducing acid mine drainage.

On the Influence of Recycled Graphite Properties for Anode Preparation and Efficiency in LIBs

The consumption of rechargeable batteries, and especially lithium-ion batteries (LIBs) has exponentially grown since their first commercialization. They are currently dominating the market, both for stationary and mobile applications: from one LIB to power a cellphone to a pack of six cells in a laptop or thousands in an electric vehicle (E.V.). In short, the number of LIBs currently in use and in need for end-of-life management in the coming years is tremendous. Furthermore, considering the new regulations following commitments to allow for the energy transition, the E.V. market is expected to continue to grow, which on one hand implies a surge in the international battery demand, which incidentally puts pressure on the stock and on the availability of the valuable elements composing the battery, and on the other hands, requires solving their end-of-life management. For both these reasons, the LIBs recycling became a necessity as it offers several advantages, including: (i) providing a sustainable feedstock of battery components; (ii) avoiding mining of raw limited minerals; (iii) adding value to a system (i.e. the battery pack) that was meant to be discarded; (iv) avoiding the creation of waste.At the end of life, the LIBs are usually crushed to obtain a “black mass” from which minerals must be extracted. Nowadays, most of the spent batteries actually end their life in China, where pyrometallurgy is used (i.e. heating up the batteries to high temperature (e.g. 1000°C)) to recover cobalt, and nickel. However, lithium can not be recovered using the pyro-metallurgical process as it will be lost in the slag, as well as aluminium. Graphite is also destroyed in this process. Another technique is hydrometallurgy to recover the valuable metals in solution as well as the graphite as a solid. Moreover, lithium can also be recovered in this recycling process, by precipitation of lithium carbonate. However, the currently used hydrometallurgy processes often imply the use of H2SO4/H2O2 mixture which is detrimental to the graphitic structure and lead to acidic wastewater generation.Even though graphite was recently classified as “critical” by Canada, so far, the focus in the LIBs recycling field wad mainly placed on the recovery and regeneration of the critical minerals that compose the cathode (Lithium, Cobalt, Nickel), due to their high value on the market. This explains the currently developed methods that were detrimental to this long forgotten critical mineral. Therefore, we hereby present a recycling process that, in addition to being efficient for the recovery of transition metals, takes into account the regeneration of graphite. As demonstrated with XRD, Raman and analytical results, by developing and tailoring a soft hydrometallurgy leaching treatment of black mass, the graphitic structure of the residues was preserved while still being purified from their contaminants. In addition, the large acidic wastewater usually generated by hydrometallurgy was avoided. It was also demonstrated that thanks to the preservation of the graphitic structure during its purification, the material only needed low temperature and soft conditions for its refinement. The physico-chemical properties of this new graphite feedstock were thoroughly evaluated and compared to battery-grade graphite to understand their implications in both the electrode making and LIB efficiency.

Preparation of positively charged acid-resistant hollow fiber nanofiltration membrane with excellent separation performance by surface modification

There is a significant requirement for acid-resistant nanofiltration (NF) membranes with positively charged surface in order to effectively treat and recycle acidic industrial wastewater that contains heavy metal ions. Currently, acid-resistant nanofiltration membranes still exhibit low water permeance and typically display only weak positively charged or even negatively charged surface, which presents a vast challenge for the effective removal of heavy metal ions. In this work, we successfully produced a positively charged hollow fiber (HF) NF membrane with outstanding water permeability by combining interfacial polymerization and surface modification approaches. The interfacial polymerization reaction was conducted on the inner surface of an HF polysulfone substrate using polyethyleneimine as the aqueous monomer and cyanuric chloride as the organic monomer. This process results in the formation of a positively charged polyamine selective layer. Subsequently, the surface of the selective layer was modified with an aqueous solution of (3-bromopropyl) trimethylammonium bromide (BPTAB) via a Hoffman alkylation process, which increases the positive charge density and hydrophilicity of the HF NF membrane. Consequently, the BPTAB-modified HF NF membrane achieves a water permeance of 44.5 L m−2 h−1 MPa−1, which is a 130 % increase compared to the unmodified baseline HF NF membrane. Meanwhile, it exhibits excellent desalination performance, corresponding to a rejection of 97.3 %, 99.3 % and 99.1 %, for MgCl2, CoCl2 and MnCl2, respectively. Additionally, it demonstrates excellent resistance to acids, which remains a 93.3 % MgCl2 rejection after being submerged in pH = 1 HNO3 solution for 60 d.

Municipal secondary-treated effluent data seem to be a suitable source of information for human viral trends

Employing a long-time series of municipal wastewater samples collected in 2020, the present study aims to confirm whether the appearance of SARS-CoV-2 influences the environmental load and behaviour of both JC Virus and Norovirus, determine the ability of the selected wastewater treatment plant (WWTP) to remove viral genomes, and assess if secondary-treated effluent data is somehow related to the incidence of the viral diseases reported by the local hospital. From the 11 raw influent and 52 secondary-treated effluent samples tested, JC Virus data present an occurrence frequency of 100 %, showing two different abundance patterns along the year, before and after the appearance of SARS-CoV-2. The constant detection of JC nucleic acids in wastewater reinforces the idea that urine is responsible for transmitting this virus. The Norovirus genogroup (G) II was detected more frequently than GI, both in influents and effluents, and their characteristic incidence peaks were not observed in late 2020. Regarding SARS-CoV-2 RNA, it appeared only in 5.8 % of the effluents, possibly due to the iron dosing used by the WWTP to reduce both phosphorus and organic matter concentrations in order to meet the requirements of European legislation, and/or the pre-filtration laboratory step which neglected the possibility of viral association with the solid fraction. The results suggest a poor performance of the WWTP, since Log removal values below 1.8 were determined. We were able to trace the development of local Norovirus outbreaks in the effluent samples to some extent, suggesting that secondary-treated effluents may be used to monitor human viruses by following viral nucleic acid levels.