Chemical Wastewater Research Articles

Role of Ionic Strength in Solubility of Salts in India

Purpose: The aim of the study was to assess the role of ionic strength in solubility of salts in India. Methodology: This study adopted a desk methodology. A desk study research design is commonly known as secondary data collection. This is basically collecting data from existing resources preferably because of its low cost advantage as compared to a field research. Our current study looked into already published studies and reports as the data was easily accessed through online journals and libraries. Findings: Ionic strength increases, the electrostatic interactions between oppositely charged ions in the salt and the surrounding ions in the solution are weakened, leading to changes in solubility. Higher ionic strength often results in greater solubility of salts due to the shielding effect, which reduces ion pairing and prevents precipitation. However, in some cases, extremely high ionic strength may lead to the "salting out" effect, where solubility decreases as ions compete for solvation. This relationship is essential in fields like chemistry and environmental science, where understanding solubility is crucial for processes such as crystallization and precipitation reactions. Implications to Theory, Practice and Policy: Debye-hückel theory, van’t hoff factor and colligative properties theory may be used to anchor future studies on the role of ionic strength in solubility of salts in India. Industries involved in chemical manufacturing and wastewater treatment should adopt protocols that account for ionic strength when designing their processes. Policymakers should establish regulatory frameworks that promote the inclusion of ionic strength considerations in environmental assessments.

Electrochemical removal of ethylene glycol monobutyl ether in aviation industry wastewater using a porous Ti4O7/Ti electrode

Titanium alloy chemical milling wastewater contains a significant amount of ethylene glycol monobutyl ether (EGBE), which is toxic and difficult to be degraded by microorganisms, and the emission will lead to severe environmental pollution. To solve this problem, the electrocatalytic oxidation method was employed to remove EGBE in the wastewater, in which a porous Ti4O7/Ti electrode were prepared and employed as the anode, while stainless steel acted as the cathode. The effects of current density, interelectrode distance, and stirring mode on the COD removal rate were also investigated. Results show that the COD of the wastewater significantly decreases from 12410 to 15 mg L−1 after 16 h of electrolysis at 10 mA cm−2 and electrode spacing of 1.0 cm as well as aeration stirring at 100 mL min−1. Moreover, pilot-plant scale testing reveals that the COD decreasing from 11980 to 183 mg L−1 after 24 h of electrolysis. Consequently, the utilization of porous Ti4O7/Ti electrode as anode in the electrocatalytic oxidation method presents significant potential in removal of EGBE in aviation industry wastewater.

A deep treatment process for chemical polishing wastewater towards resource recovery: Optimization and performance

The chemical polishing industry generates abundant wastewater that contains high concentrations of phosphoric acid and metal ions. In light of the rapid growth of the economy and the stringent demands for sustainability, developing cost-effective and energy-efficient technologies for wastewater treatment is crucial. Herein, an EPRC-ICT-ANT process integrating electrodialysis, iron contact, and alkali neutralization, was proposed to deeply treat chemical polishing wastewater and achieve optimal recovery of acid, phosphorus, and aluminum. The results indicated that with the electrochemical phosphoric acid recovery cell (EPRC), the maximum recovery efficiency and final phosphoric acid concentration were 34.6 % and 25.2 g/L. Following the iron contact tank and alkali neutralization tank (ICT-ANT) treatment, a remarkable 99.17 % removal of Al3+ and 49.5 kg/t wastewater yield of AlPO4 were achieved. Simultaneously, the released Fe2+ and remaining PO43- triggered the rapid formation of vivianite with a yield of 120.7 kg/t wastewater. This comprehensive treatment strategy led to the near-complete removal of Al3+ and PO43- (∼100 %) with an impressive recovery of Al3+ (∼100 %) and PO43- (75.7 %), emphasizing its immense potential for chemical polishing wastewater treatment.

304L Austenitic Stainless Steel Corrosion Studies in Neutral Environment in Presence of Sulfite Ions

Abstract This paper examined the influence of the sulfite concentration introduced in the electrolyte added to the neutral solution (1 mol L-1 Na2SO4) on the corrosion process of 304L stainless steel material. 304L. The accelerated effect of sulfite ions under corrosion rate of 304L austenitic stainless steel was demonstrated using electrochemical techniques such as linear sweep voltammetry at a low scan rate −1 mV s−1, the Tafel slope method, chronoamperometry, and electrochemical impedance spectroscopy. Electrochemical studies were conducted using a BioLogic SP150 potentiostat/galvanostat. Stainless steels are the most varied and intricate group among all steels. Among them, 304L austenitic stainless steel is one of the most commonly utilized alloys, prized for its excellent corrosion resistance and strength, hygienic and aesthetic properties, affordability, good formability, and effective weldability. [1-3]. In modern industry, the amount of austenitic stainless steel represents only about 2% of the total steel production manufactured globally. This type of steel is commonly employed in chemical engineering, metal extraction, desalination and wastewater treatment plants, the oil and gas sector, transportation and aerospace industries, the food and beverage sector, as well as in architecture and construction engineering. [1].

Development and performance of microalgae-based symbiotic systems for high-strength chemical oxygen demand wastewater treatment from the sugar mills

Agricultural and agro-industrial activities have risen exponentially to meet the ever-growing demand for food, energy, and other important resources. High freshwater consumption occurs in these sectors and is discharged as effluent containing excessive organic loads that require treatment. In this study, microalgal, bacterial, and fungal (yeast) isolates native to the sugar industry effluent were screened for effective chemical oxygen demand (COD) removal from wastewater when co-cultured. The microalgae-bacteria consortium (MBC) comprised Chlorella sorokiniana A7 and three bacterial strains including Rhodococcus sp. B009, Bacillus sp. B010, and B013; whilst the microalgae-yeast consortium (MYC) consisted of Chlorella sorokiniana A7 and Saccharomyces cerevisiae Y2. When the Chlorella sorokiniana-based symbiotic systems were characterized in sugar industry wastewater, excellent COD removal efficiencies were achieved compared to the axenic Chlorella sorokiniana A7. The COD removal efficiencies were 86 %, and 71 % after 96 h of cultivation for MBC, and MYC, respectively. After 168 h of cultivation in wastewater, ≥90 % of COD removal efficiency was observed in both MBC and MYC systems. The MYC also showed improved chlorophyll-a content, photosynthesis, and respiration in Chlorella sorokiniana A7. This study has demonstrated the efficiency of Chlorella sorokiniana-based consortium systems that could be used as eco-friendly and sustainable bioremediation tools for high-strength COD wastewater streams. An insight into mechanisms of interactions between Chlorella sp., and co-cultured microbial strains grown in sugar industry wastewater still needs further studies.

Optimization of Combined Pre-Treatment Process for Bleaching of Cotton Woven Fabric Using Box–Behnken Design

ABSTRACT The conventional bleaching process for cotton woven fabrics is characterized by high consumption of chemicals, water, and energy, resulting in significant environmental impact through elevated energy use and wastewater discharge. To address these concerns and align with sustainable development goals, there is an urgent need for eco-friendly alternatives that minimize environmental footprint while maintaining fabric quality. This study presents the development and optimization of a novel one-bath pre-treatment process for cotton bleaching, employing the Box-Behnken design to enhance sustainability. The optimized process utilizes 32% hydrogen peroxide and 12% sodium hydroxide based on fabric weight, operating at 90°C. The application of the Box-Behnken design facilitated substantial reductions in chemical usage, energy consumption, and wastewater output. The results demonstrated notable improvements in fabric properties, with a whiteness index of 139.5, weight loss of 7.9%, and tensile strengths of 404.9 N (warp) and 259.5 N (weft). Moreover, fabric absorbency increased by 9.3% compared to conventional methods. The findings underscore the efficacy of the Box-Behnken design in optimizing a more sustainable and eco-friendly bleaching process, which not only significantly enhances fabric performance but also offers considerable environmental benefits. This approach presents a promising solution for the textile industry to achieve greener practices while maintaining high-quality standards.

Development and application of metal–organic frameworks and spherical carbon particles for efficient recovery of phenols and oils from coal chemical wastewater: A new full-process adsorption treatment mode

To address the challenges of high energy consumption and low efficiency in recovering phenols and oils from coal chemical wastewater (CCW), this study focused on the design and synthesis of metal–organic frameworks and spherical carbon particle (MOFs/SCP) adsorbents with a high adsorption capacity and ease of desorption. Additionally, a new comprehensive treatment mode named “adsorption-desorption-regeneration-recovery” (ADRR) was developed to efficiently recover phenols and oils from CCW. The results revealed that the ADRR treatment mode maintained high adsorption and desorption efficiencies of MOFs/SCP, which remained consistently above 95 %. Additionally, methanol regeneration reached ∼ 90 %, and the recovery efficiency of phenols and oils was ∼ 83 %. The analysis of the adsorption behavior model indicated that the adsorption of phenols and oils by MOFs/SCP mainly involved monolayer chemical adsorption characterized by spontaneity, heat absorption, and disorder. The dynamic adsorption model exhibited a strong correlative ability to predict and assess the adsorption capacity, rate, equilibrium, and operating parameters. Finally, structural analyses and molecular dynamics simulations revealed that the micro-interaction mechanisms between MOFs/SCP and phenols and oils mainly depended on the distinctive hydrophobic nature and porous adsorption capabilities of MOFs/SCP. These interactions were mainly facilitated by electrostatic interactions, π–π interactions, and hydrogen bonding. The findings of the study are crucial for achieving high-value recovery of phenols and oils from CCW and, promoting the clean and sustainable growth of the coal chemical industry.

Research on a harmless treatment method for oily sludge in coal chemical wastewater and the pollutant transformation mechanism of oily sludge during the treatment process

This study developed an ultrasound synergistic subcritical hydrothermal treatment method (U-SHT) to address the challenges posed by the high oil and water content, complex composition, and hazardous nature of oily sludge (OS) generated during the pretreatment of coal chemical wastewater. The study investigated the efficiency of this method for the harmless disposal and resource recovery of OS, and the migration-transformation mechanism of hazardous organic pollutants in OS. The findings revealed that U-SHT achieved a removal efficiency of chemical oxygen demand in OS of 91.16 %, an oil resource recovery efficiency of 96.60 %, and a residual oil rate of 0.28 %, meeting API emission standards. Further research indicated that the solubilizing effect of the surfactant on the oil enhanced the demulsifying effect of ultrasonic cavitation on the emulsified structure of OS, enabling ultrasound to efficiently release and disperse pollutants within OS. This promoted the decomposition and transformation of pollutants under subcritical hydrothermal conditions, with synergistic removal efficiencies for typical pollutants such as long-chain alkanes, polycyclic aromatic hydrocarbons, and phenols reaching 96.61 %, 97.63 %, and 97.76 %, respectively. Economic evaluation indicated that the cost of OS treatment was $29.66/m3, significantly lower than existing methods, demonstrating promising practical application prospects.

Tuning FeO covalency boosts catalytic ozonation over spinel oxide for chemical industrial wastewater decontamination

AbstractHeterogeneous catalytic ozonation (HCO) emerges as a promising chemical industrial wastewater treatment solution, offering enhanced ozone utilization and reduced secondary pollutants. However, challenges in scaling HCO arise from a limited understanding of the catalytic mechanisms of metal oxides, particularly in generating active ozone sites. Here, we demonstrated the improvement of catalytic ozonation efficiency by enhancing the covalent bonding between FeO in Fe/Co spinel oxides. This alteration exploits the stronger electron‐donating capacity of Fe (II), enhancing FeOM bonds and electron enrichment at iron sites, leading to a significant reduction in the activation energy for ozone. Pilot experiments demonstrated a 75.3% COD removal efficiency and a threefold increase in ozone utilization efficiency compared to pure ozone system for chemical industrial wastewater treatment. This study not only advances our understanding of spinel oxides in ozone catalysis but also opens new avenues for practical HCO applications in water treatment.

On the FT-ICR mass spectrometry analysis of dissolved organic matter released by adsorbent during coal chemical wastewater treatment

This study analyzed the dissolved organic matter (DOM) released by adsorbent during wastewater treatment. It was found that the adsorption method resulted in an organic removal efficiency of over 97 % for coal-to-olefin (CTO) wastewater, with the lowest value of 15.7 mg/L. The Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FT-ICR MS) detected 4111 DOM in the wastewater, 4052 remaining DOM after first-stage anthracite (ANC) adsorption, and 1013 after second-stage macroporous adsorption resin (MAR). The removal degree of lipids in wastewater was the highest, followed by aliphatic/amino-acid/mini-peptides and lignin. During the adsorption process, the proportion of halogenated compounds (HCs) declined from 59.86 % to 38.63 % and 21.67 %. Additionally, freshly produced 2035 and 311 DOMs were found in the adsorption effluent of ANC and MAR, respectively, with HCs accounting for 34.71 % and 67.96 %. Upon flowing ultra-pure water through ANC and MAR, the effluent dissolved organic carbon (DOC) ranges were 1.118–3.574 mg/L and 1.014–2.557 mg/L, respectively. There were 159 and 131 species of DOM detected, respectively, with HCs content of 59.06 % and 45.02 %. Comparative experiments revealed the complex components of the wastewater promoting the release of organic matter on the adsorbent surface that further reacted to generate organic matter. However, fewer substances were released by the adsorbent.

Preparation of low-cost sludge-based highly porous biochar for efficient removal of refractory pollutants from agrochemical and pharmaceutical wastewater

Producing a high-performance sludge biochar through a feasible method is a great challenge and is crucial for practicability. Herein, we reported a highly porous sludge biochar synthesized from agrochemical-pharmaceutical and municipal sludge blends through a novel pyrolysis-acid treatment-post pyrolysis method. The optimized biochar named ASMS91 obtained interconnected pores with a total pore volume of 0.894 cm3/g and a surface area of 691.4 m2/g through extended acid wash and subsequent post-pyrolysis, which is superior to non-activated sludge biochar. ASMS91 removed 45.3 % of wastewater COD (156 mg/L) in 24 h, which was rapid and higher performance than commercial activated carbon (1000 iodine number). This outstanding performance is due to its high adsorption ability of long-chain aliphatic compounds (e.g., 2,4-Di-tert-butylphenol, neophytadiene and eicosane) into mesopores, which accounts for 71.8 % of pore filling. ASMS91 was highly recyclable, and adsorption was reduced by only 5.3 % after the 4th cycle. It also outperformed other sludge biochar in literature in removing perfluorooctanoic acid (PFOA), 6:2 fluorotelomer sulfonate (6:2 FTS), sulfamethoxazole, methylene blue, and methylene orange. Finally, the feasibility of our proposed method was validated by a brief techno-economic analysis. This feasible approach may support future research regarding sludge valorization and low-cost chemical wastewater treatment.

Self-assembled iron (II) phthalocyanine modified oxygen vacancy-rich WO3 nanofibers with unique S-scheme heterojunctions for efficient tetracycline hydrochloride degradation and CO2 reduction

The advancement of efficient photocatalysts is crucial for the conversion of carbon dioxide (CO2) into chemical fuels and wastewater treatment, due to the significant role in promoting energy sustainability and environmental remediation. In this work, we synthesized iron (II) phthalocyanine modified oxygen vacancy-rich (FePc/OVs-rich WO3) photocatalyst with an S-scheme structure through electrospinning-calcination and electrostatic self-assembly. The optimized FePc/WO3–2 nanocomposite demonstrated approximately 3.69-fold enhancement in photoactivity for the conversion of CO2 to CO and CH4, as compared with the OVs-rich WO3 nanofibers. Furthermore, the FePc/WO3–2 catalyst demonstrated outstanding efficacy in activating peroxymonosulfate (PMS) for the degradation of tetracycline hydrochloride (TC), achieving an efficiency of 84.9 % within 60 min and a rate constant of 0.924 h−1. The improved photocatalytic performance is attributed to the prolonged absorption of visible light, enhanced charge separation and the increased density of catalytic reaction sites. The enhancement in charge separation is predominantly linked to the unique S-scheme transfer process, which is characterized by non-overlapping optical absorption, in-situ X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT). This process is further facilitated by the catalytic activity of central Fe2+ in FePc for the degradation of TC. The π-π interaction between FePc and the WO3 nanofibers, which have a high concentration of oxygen vacancies, resulted in a fast electron transfer pathway, allowing efficient transport of photoelectrons. This paper comprehensively examines the advancement of high-performance S-scheme FePc/OVs-rich WO3 photocatalysts for the photocatalytic reduction of CO2 and degradation of tetracycline through the photo-assisted activation of PMS.

Improvement of Coagulation and Membrane Filtration Performance in Hybrid Coagulation-UF-RO System for Chemical Mechanical Polishing Wastewater Treatment: Effect of Coagulants

Improvement of Coagulation and Membrane Filtration Performance in Hybrid Coagulation-UF-RO System for Chemical Mechanical Polishing Wastewater Treatment: Effect of Coagulants

Systematic Review of Poultry Slaughterhouse Wastewater Treatment: Unveiling the Potential of Nanobubble Technology

Aeration is crucial for the biological decomposition of organic compounds in wastewater treatment. However, it is a highly energy-intensive process in traditional activated sludge systems, accounting for 50% to 75% of a plant’s electricity consumption and making it a major cost driver for wastewater treatment plants. Nanobubbles (NBs), characterized by their tiny size with diameters less than 200 nm, have emerged as a potential alternative to the low efficiency of aeration and high sludge production in aeration systems. NBs proved effective in removing COD and other pollutants from wastewater. For example, when applied in flotation, aeration, and advanced oxidation, NBs achieved up to 95%, 85%, and 92.5% COD removal, respectively. Considering the recent advancements in wastewater treatment, a compelling need arises for a thorough investigation of the effectiveness and mechanisms of nanobubbles in this field. This systematic review summarizes recent advancements in understanding nanobubbles (NBs) and their unique properties that enhance physical, chemical, and biological water and wastewater treatment processes. Moreover, this study reviews various methods for generating NBs and provides an in-depth review of their applications in wastewater treatment, with a particular focus on poultry slaughterhouse wastewater (PSW) treatment.

Construction of coal fly ash-based spherical grain adsorbents and their adsorption characteristics on phenolic compounds

Addressing the significant emissions and severe pollution hazards posed by coal fly ash waste in the coal chemical industry, as well as the challenges in recovering phenolic substances from coal chemical wastewater, this study utilized coal fly ash as a raw material to construct two types of spherical grain adsorbents: coal fly ash and coal gangue spherical grain (CFAGsg) and coal fly ash and pyrite spherical grain (CFAPsg). The adsorption performance of CFAGsg and CFAPsg towards phenolic substances in coal chemical wastewater was investigated. The research results demonstrated that CFAGsg and CFAPsg exhibited adsorption capacities of 20.31 mg/L and 30.42 mg/L for phenol, respectively, and maintained stable adsorption performance even after multiple regeneration cycles. Further analysis using kinetic, isotherm, and thermodynamic models, along with various characterization techniques, revealed that the adsorption of phenol onto CFAGsg and CFAPsg was primarily governed by physical and chemical adsorption, involving an endothermic reaction. Moreover, the study on the adsorption mechanism of phenol revealed that the adsorption behavior of CFAGsg and CFAPsg was mainly driven by pore filling, π-π stacking, and hydrogen bonding. Additionally, hydrophobic interactions were involved in the adsorption of phenol onto CFAGsg, while surface complexation forces played a role in the adsorption of phenol onto CFAPsg. Overall, the research findings provide vital theoretical support and practical application prospects for the high-value utilization of coal fly ash and the clean production of the coal chemical industry.

MnFe2O4/MoS2 catalyst used for ozonation: optimization and mechanism analysis of phenolic wastewater treatment.

The performance of catalytic ability of MFe2O4/MoS2 in the ozonation process was investigated in this work. The synthesized MnFe2O4/MoS2 was optimize prepared and then characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photo-electron spectroscopy, and magnetic saturation strength. The results showed that when Cphenol = 200 mg/L, initial pH = 9.0, Q = 0.10 L/min, and CMnFe2O4/MoS2 = 0.10 g/L, MnFe2O4/MoS2 addition improved the degradation efficiency of phenol by 20.0%. The effects of pH, catalyst dosage, and inorganic ions on the phenol removal by the MnFe2O4/MoS2 catalytic ozonation were investigated. Five cycle experiments proved that MnFe2O4/MoS2 had good recyclability and stability. MnFe2O4/MoS2 also showed good catalytic performance in the treatment of coal chemical wastewater pesticide wastewater. The MnFe2O4 doped with MoS2 could provide abundant surface active sites for ozone and promote the stable cycle of Mn2+/Mn3+and Fe2+/Fe3+, thus generating large amounts of •OH and improving the degradation of phenol by ozonation. The MnFe2O4/MoS2/ozonation treatment system provides a technical reference and theoretical basis for industrial wastewater treatment.

Recent Advances in Metal-Organic Framework (MOF)-Based Composites for Organic Effluent Remediation.

Environmental pollution caused by organic effluents emitted by industry has become a worldwide issue and poses a serious threat to the public and the ecosystem. Metal-organic frameworks (MOFs), comprising metal-containing clusters and organic bridging ligands, are porous and crystalline materials, possessing fascinating shape and size-dependent properties such as high surface area, abundant active sites, well-defined crystal morphologies, and huge potential for surface functionalization. To date, numerous well designated MOFs have emerged as critical functional materials to solve the growing challenges associated with water environmental issues. Here we present the recent progress of MOF-based materials and their applications in the treatment of organic effluents. Firstly, several traditional and emerging synthesis strategies for MOF composites are introduced. Then, the structural and functional regulations of MOF composites are presented and analyzed. Finally, typical applications of MOF-based materials in treating organic effluents, including chemical, pharmaceutical, textile, and agricultural wastewaters are summarized. Overall, this review is anticipated to tailor design and regulation of MOF-based functional materials for boosting the performance of organic effluent remediation.

The Photocatalytic Ozonation Oxidation Synergistic Degradation on Organic Pollutants In Coal Chemical Phenol-Ammonia Wastewater by Two-Dimensional Nanosheets Bi2WO6

The Photocatalytic Ozonation Oxidation Synergistic Degradation on Organic Pollutants In Coal Chemical Phenol-Ammonia Wastewater by Two-Dimensional Nanosheets Bi2WO6

Hazard Identification and Risk Analysis of Liquid Effluent Treatment Plant Apply in Chemical Process Industry

The chemical process industry is one of the categories of highly polluting industries and generates strong wastewater of high COD along with hazardous waste which requires effective treatment and disposal/reuse of effluents. In this review, the various sources of wastewaters in the chemical industry are identified and the best available technologies to remove them are critically evaluated. The aim of the present research work was to determine the behavior of various parameters of the chemical wastewater. During the entire study evaluate, monitor, and check various environmental parameters whether they are complying with a given standard or not given by regulatory authority at chemical Industry,. The India based industry produced bulk drugs, fatty acids, fatty alcohol, food additives, personal care products, and others. The monitoring data of the effluent treatment plant will give information on the pollution control by the company and the management of waste. Overall analysis showed that there is no significant difference in pH, BOD, COD, and ammoniacal Nitrogen. The use of conventional treatment methods along with membrane reactors and advanced post-treatment methods resulting in a Coagulation wastewater treatment technology appears to be the best

Hydrothermal synthesis of high crystallinity ZSM-5 zeolite from coal gasification coarse slag and mother liquor circulation for efficient coal chemical wastewater purification.

A hydrothermal synthesis method was developed to produce high crystallinity ZSM-5 zeolite using coal gasification coarse slag (CGCS) as the raw material. Instead of the expensive NaOH(s.), Na2SiO3(s.) was utilized to activate, depolymerize, and recombine Si and Al elements in the CGCS. The mother liquor circulation technology was employed to recover and reuse raw materials and residual reagents (Na2SiO3(aq.) and TPABr), reducing waste emissions and enhancing resource utilization efficiency. The synthesized ZSM-5 had a specific surface area of 455.675 m2g-1, pore volume of 0.284 cm3g-1, and pore diameter of 2.496nm. The influence of various factors on the morphology and crystallinity of ZSM-5 was investigated, resulting in the production of ZSM-5 with higher specific surface area and pore volume. Adsorption experiments showed that WU-ZSM-5 exhibited a removal efficiency of 85% for ammonia nitrogen (NH4+-N(aq.)), validating its effectiveness in coal chemical wastewater purification. The mother liquor recycling technology enabled zero-emission utilization of solid waste resources and improved the utilization rate of alkali and template to 90%. These results demonstrate the potential application of the developed method in the efficient treatment of coal chemical wastewater.