Field Of Wastewater Treatment Research Articles

Recent Advances in the Synthesis, Characterization, and Application of Carbon Dots in the Field of Wastewater Treatment: A Comprehensive Review

Carbon dots (CDs), as a revolutionary nanomaterial, exhibit unique advantages in terms of wastewater treatment, offering new opportunities for the development of water treatment technologies due to their simple synthesis methods, excellent biocompatibility, tunable optical properties, and favorable environmental performance. This review systematically discusses the synthesis methods, structural characteristics, and application progress of carbon dots in wastewater treatment, highlighting several key findings. (1) Excellent adsorption performance: CDs can effectively remove heavy metal ions, dyes, and organic pollutants from water. (2) Outstanding photocatalytic performance: Some carbon-dot-enhanced photocatalytic systems can efficiently remove pollutants under visible light. (3) Exceptional selective detection ability: CDs are capable of highly sensitive detection of heavy metals and organic pollutants in water, with the detection limits reaching the nanomolar level. (4) Enhanced membrane separation performance: The high water flux and excellent selectivity of carbon-dot-modified membranes make them suitable for efficient water treatment and water quality separation. (5) Enhancement of biological treatment: In biological treatment systems, CDs can significantly improve the microbial activity and electron transfer efficiency to enhance the efficiency of biological degradation processes. (6) Sustainable utilization of waste as a raw material and regeneration of CDs are conducive to reducing the cost of preparation of CDs. These findings indicate that CDs have broad application potential in wastewater treatment. Furthermore, this review looks ahead to the future development directions of CDs in wastewater treatment, proposing potential innovations in catalytic performance enhancement, cost control, and practical applications, aiming to provide important references and guidance for future research and industrial application of CDs in wastewater treatment.

Drift Correction Method of Wastewater Treatment Model Based on Transfer Learning Across Time Scales

Data is the core foundation of intelligent operation and maintenance, but currently, there is generally insufficient data for wastewater treatment plants, and the status of wastewater treatment systems dynamically evolves with the changes in the internal and external environment. The intelligent operation and maintenance of wastewater plants face difficulties in modeling and model drift caused by system evolution. In response to this issue, the summer and winter seasons with significant differences in wastewater temperature, wastewater quality, and microbial status were selected as typical comparison scenarios. The mechanism model was combined with neural networks to establish a wastewater treatment model drift correction method based on cross-time scale transfer learning. Firstly, in response to the problem of insufficient data, an activated sludge model （ASM） was established and calibrated. Summer operating data was used as input to simulate and calculate operating parameters and effluent data, generating a simulated operating dataset to achieve data augmentation and quality improvement. This was used to train a multi-layer perceptron neural network （MLP） model. The results showed that the average simulation accuracy of the MLP model for summer effluent COD, ammonia nitrogen, total phosphorus, etc., was all over 95%. This indicates the feasibility of training MLP models based on ASM-generated data. Then, the MLP model was used to guide the operation of the pilot A2O project. Experimental data analysis showed that the model drift phenomenon was significant in the field of wastewater treatment. During the operation of the pilot plant guided by the summer model, the accuracy of the predicted values gradually decreased, and the average prediction accuracy of the model for effluent COD gradually decreased from 98.14% to 75.18%. The phenomenon of model drift required effective correction to maximize the effectiveness of the model. In response to the problem of model drift caused by a significant decrease in simulation accuracy in winter operating conditions, a transfer learning approach was introduced. The winter measured data was used as the target domain dataset, and the MLP model was used as the pre-trained model for transfer learning. The experimental results showed that transfer learning methods can significantly improve model performance. After transfer learning, the average simulation accuracy of the MLP model for effluent COD, ammonia nitrogen, total nitrogen, and total phosphorus was relatively improved by 28.58%, 184.44%, 207.56%, and 100.51%, with absolute improvement values of 21.49%, 60.79%, 58.14%, and 46.74%, respectively. This indicates that the cross-time scale transfer learning method proposed in this study can significantly improve model performance, effectively solve model drift problems, and achieve a model-following response to the dynamic evolution of wastewater treatment systems. This study indicates that transfer learning based on pre-trained models only requires a small amount of engineering data and computational complexity to achieve model updating and correction. Compared to model retraining, this method reduces computational complexity and reduces the dependence on engineering data during data-driven model updates.

Metal oxide nanoparticles: Synthesis and applications in energy, biomedical, and environment sector

AbstractMetal oxide nanoparticles (MONPs), pivotal in cutting‐edge research, are examined comprehensively in this article. Encompassing definition, types, and applications, the focus intensifies on synthesis methods. Detailed discussions include chemical synthesis approaches for silver oxide, zinc oxide, nickel oxide, copper oxide, and tin oxide NPs. Additionally, the article emphasizes the burgeoning significance of green synthesis methods in tailoring these NPs. The applications section underscores their pivotal role in wastewater treatment, water splitting, and biomedical fields. This targeted resource offers in‐depth insights into MONP synthesis, bridging the gap between traditional and environmentally conscious methodologies, for researchers and practitioners in emerging technologies. In this article, future perspectives are also discussed.

Three birds with one stone: Preparation of multifunctional Fe-MOF/PAN nanofiber membranes for wastewater treatment

In this research, a new NH2-MIL-88B(Fe)/polyacrylonitrile nanofiber membrane (NPNFM) was synthesized utilizing a straightforward electrospinning technique. The morphological characteristics and performance of nanofiber membranes were finely tuned via adjusting the dosage of NH2-MIL-88B(Fe) (NM88B, the “stone”). The prepared NPNFM exhibits superhydrophilicity/underwater superoleophobicity, coupled with outstanding photo-Fenton self-cleaning ability (the first two “birds”). This membrane efficiently and swiftly facilitated the separation of various surfactant-stabilized emulsions under gravitational force, achieving a separation efficiency and flux of up to 99.5 % and 350.3 L m-2h−1, respectively. The fouling on the membrane surface can be rapidly decomposed, attributing to the superior photo-Fenton activity of NM88B. Furthermore, the organic dye methylene blue (MB) was degraded by 97.4 % within 40 min under the catalytic influence of the membrane. The nanofiber membrane has good mechanical properties and its tensile strength is about 2.3 times that of the original membrane attributing to the good compatibility between NM88B and the membrane matrix (the third “bird”). This study proposed new Fe-MOF-based photo-Fenton multifunctional membranes with the characteristics of environmental stability and high efficiency in wastewater treatment fields.

Study on the degradation of methyl orange by UV-acetylacetone advanced oxidation system

In recent years, Acetylacetone (abbreviated as AA) has garnered considerable scientific interest, particularly in the field of dye wastewater treatment due to its distinctive enol-keto structures. In this work,degradation of methyl orange(MO) by UV/AA process was explored. Effects of AA dosage, MO concentration, initial pH value and water matrices were investigated.Experimental results showed that under conditions of 298 K, a pH of approximately 5.73, a stirring speed of 1150 rpm, an initial MO concentration of 15 mg/L and an AA dosage of 0.5 mM, the decolorization rate reached nearly 98.4 % after 12 min of photolysis. The decolorization process fitted well with the pseudo-zero-order reaction model in the UV/AA system with an R2 value greater than 0.990. The reaction rate increases as the pH decreases; at approximately pH 2.0, the decolorization rate is 99.3 % after 6 min, while at approximately pH 9.0, it is only 41.2 %. 10 mM HCO3⁻significantly inhibit the system, 0.1 mM Cl⁻has a slight promoting effect at low concentrations but inhibits at high concentrations and NO3⁻inhibits the reaction while SO42- has minimal impact at a concentration of 0.1–10 mM .0.1 mM iron ions accelerated the reaction.The sodium citrate, a printing and dyeing auxiliary, has negative impacts on the MO degradation. Free radical capture experiments and Electron Paramagnetic Resonance (EPR) tests reveal that singlet oxygen (¹O2) is the primary active species in the UV/AA system. UV-Vis absorption spectroscopy indicates that azo bonds are largely destroyed after 12 min, with a decrease in AA concentration as the reaction proceeds. Liquid chromatography-mass spectrometry (LC-MS) results suggest a possible conversion pathway for MO during the UV/AA advanced oxidation process.

Chitosan-Promoted TiO2-Loaded Double-Network Hydrogels for Dye Removal and Wearable Sensors.

The loading of photocatalysts on hydrogels can significantly reduce the loss of catalysts and effectively prevent secondary contamination, thus demonstrating great application potential and advantages in the field of wastewater treatment, especially in the removal of dyes. Herein, the semiconductor TiO2 was successfully loaded into a polyacrylic acid/chitosan (PAA/CS) double-network (DN) hydrogel, which exhibited superior removal of dyes in wastewater such as MG, MB, MV, and RhB. The dye degradation process followed first-order kinetics, and the first-order rate constants for dye degradation were further calculated under UV light irradiation. Furthermore, the photocatalytic mechanism of the hydrogel was explored and analyzed. More interestingly, the PAA/CS-TiO2 DN hydrogel has excellent tensile properties and superior electrical conductivity, which can be assembled into flexible sensors for real-time monitoring of mechanical deformations and human joint motions. It is envisioned that these excellent properties make hydrogel photocatalysts promising for a wide range of applications.

Preparation of a novel organic-inorganic composite sludge bioflocculant (SBF) from dewatered sludge as raw material: Characteristics, flocculation mechanism and application for domestic sewage

In this work, a green sludge bioflocculant (SBF) was prepared via chemical hydrolysis of dewatered sludge and applied to flocculation of domestic wastewater. The process parameters for the preparation of the SBF were 1.80 % hydrochloric acid concentration, 60 min extraction time, and 4000 r/min centrifugation speed. SBF is polymeric flocculant composed of organic and inorganic compounds. Flocculation efficiency reached 97.31 ± 0.26 % under optimal flocculation conditions. Charge neutralization promotes the surface adsorption, bridging and net trapping and sweeping of Fe (OH)3, Al (OH)3 and active functional groups O–H/N–H and C = O in SBF, which together achieve efficient flocculation reactions. SBF had high efficiency and stable flocculation performance for phosphorus in urban domestic wastewater, and the concentration of TP in effluent was lower than 0.30 mg/L. Therefore, SBF prepared from dewatered sludge has efficient flocculation properties and is suitable for removing pollutant phosphorus, which has good application prospects in the field of wastewater treatment.

Investigating the catalytic and antibacterial behavior of cesium-doped MoO3 nanostructures against methylene blue dye and MDR E. coli with DFT analysis

Water pollution, exacerbated by inadequate water management practices, has compromised the effectiveness of traditional water treatment technologies. The integration of metal oxide-based nanomaterials in treatment systems has the potential to revolutionize the field of wastewater treatment, providing a sustainable and efficient solution to the growing global water crisis. This study focused on the fabrication of hexagonal cesium (Cs) doped MoO3 nanostructures (NSs) for their potential use as catalytic and antibacterial agents. Various structural, optical, and morphological analysis was conducted to examine these NSs. The UV–Vis spectroscopy results showed that as Cs concentration increased, the band gap energies of MoO3 decreased from 3.5 eV to 3.0 eV. The field emission scanning electron microscopy (FESEM) investigation revealed the plate-like structural morphology of MoO3 formed by overlapping one layer onto another. Cs doping effectively inhibited the recombination of photo-generated charge carriers, resulting in a significant reduction in PL peak intensity for Cs-doped MoO3 compared to MoO3. The prepared NS-reduced methylene blue dye in the absence of light under different pH conditions, reaching 86.8% with 2% Cs-doped MoO3. Density functional theory (DFT), utilizing the Heyd-Scuseria-Ernzerhof hybrid (HSE06) method, was employed to model and compute the interactions between methylene blue (MB) and Cs-doped MoO3 during MB adsorption. Bactericidal experiments on multidrug-resistant Escherichia coli showed that the NSs had remarkable antibacterial action, generating an inhibition zone of 9.15 mm at higher doses using 6% Cs-doped MoO3. Consequently, these findings offer potential significance for research in developing and implementing wastewater disinfection systems.

Pea Pod–Derived Biochar–Zeolitic Imidazolate Framework Composite for the Photocatalytic Degradation of Two Organic Dyes Crystal Violet and Victoria Blue

ABSTRACTThe rapid increase of water pollution globally is a vital environmental concern that requires the immediate attention of researchers to find new innovative ways to remove unwanted environmental pollutants from our water sources. With the advances in the field of sustainable engineering, there is a high demand for the effective utilization of biomass resources for the removal of aqueous environmental contaminants. Biochar is carbon carbon‐enriched substance obtained by biomass pyrolysis; it is inexpensive and has received wide attention in the field of wastewater treatment. Herein, we describe the synthesis of pea pod (PO) biochar‐reinforced zeolitic imidazolate framework (ZIF‐8) nanocomposite (PO@ZIF‐8) through the in situ precipitation of ZIF‐8 onto the biochar surface. The crystal growth, morphology, chemical composition, and optical characteristics of fabricated PO@ZIF‐8 nanocomposite were scrutinized through PXRD, SEM, TEM, UV‐DRS, PL, and XPS analysis. The dodecahedral‐shaped PO@ZIF‐8 particles have an average size between 140 and 160 nm. The biochar‐reinforced ZIF‐8 nanocomposite showed significantly higher photocatalytic activity than the pure ZIF‐8 for the degradation of two commonly found organic dyes crystal violet (CV) and Victoria Blue (VB) in the presence of direct sunlight irradiation. The PO@ZIF‐8 nanocomposite showed the highest degradation efficiency of ~87% and ~80% within 50 min of irradiation time at a catalyst dosage of 20 mg for 30 ppm CV and VB dye solutions at pH 8. First‐order kinetics were obeyed during the photodegradation with 0.041 and 0.030 min−1 as the constant of degradation for the removal of CV and VB. The radical scavenger experiment and the photoluminescence analysis confirm the active participation of ·OH radical in the degradation of both dyes. LC–MS and TOC analysis was also performed to determine the degradation products and for evaluation of the degradation progress. Moreover, the synthesized PO@ZIF‐8 composite also exhibit good stability till the fourth cycle with high degradation efficiency thus making it a good choice of catalyst in the field of environmental decontamination.

A Review on wastewater and its use in Agriculture in Morocco: Situation, Case Study and Recommendations

Situated in a geographical location characterized by semi-arid to dry conditions, Morocco is currently grappling with the escalating issue of water scarcity. Within the framework of the circular economy concept, the utilization of treated wastewater in agricultural practices is presently being regarded as a viable approach to address the challenges of water scarcity and pollution. In recent years, Morocco has made significant progress in the field of urban wastewater treatment through the implementation of the National Wastewater Program (PNA). Nevertheless, there have been considerable delays in the implementation of rural sanitation initiatives. In this review, we discuss Moroccan water resources, an overview of Moroccan wastewater production and treatment plants, Moroccan legislation and standards for wastewater reuse in agriculture, and conclude with a discussion of practical cases of wastewater irrigation in Morocco and the results obtained with some recommendations.

Conversion of Lignin to Nitrogenous Chemicals and Functional Materials.

Lignin has long been regarded as waste, readily separated and discarded from the pulp and paper industry. However, as the most abundant aromatic renewable biopolymer in nature, lignin can replace petroleum resources to prepare chemicals containing benzene rings. Therefore, the high-value transformation of lignin has attracted the interest of both academia and industry. Nitrogen-containing compounds and functionalized materials are a class of compounds that have wide applications in chemistry, materials science, energy storage, and other fields. Converting lignin into nitrogenous chemicals and materials is a high-value utilization pathway. Currently, there is a large amount of literature exploring the conversion of lignin. However, a comprehensive review of the transformation of lignin to nitrogenous compounds is lacking. The research progress of lignin conversion to nitrogenous chemicals and functional materials is reviewed in this article. This article provides an overview of the chemical structure and types of industrial lignin, methods of lignin modification, as well as nitrogen-containing chemicals and functional materials prepared from various types of lignin, including their applications in wastewater treatment, slow-release fertilizer, adhesive, coating, and biomedical fields. In addition, the challenges and limitations of nitrogenous lignin-based materials encountered during the development of applications are also discussed. It is believed that this review will act as a key reference and inspiration for researchers in the biomass and material field.

Eco-friendly and easy-to-prepare three-dimensional network constructed by tannic acid/polypyrrole/sodium alginate via triple action mechanism of Fe3+ for highly-efficient solar evaporation

Solar-driven interfacial evaporation (SIE) represents a promising desalination technology leveraging solar energy and seawater. Nevertheless, the majority of SIE systems face constraints such as high costs, intricate fabrication processes, and limited tolerance to salt. Therein, we designed and developed an eco-friendly, simple, and low-cost way to construct independent and elastic three-dimensional networks using tannic acid (TA), polypyrrole (PPy), and sodium alginate (SA) via the triple action mechanism of Fe3+ for efficient water evaporation (TPS-x). When the mass ratios of PPy and TA are designed as 1:2, 1:1, 2:1, and 3:1, and crosslinked with sodium alginate and FeCl3, four composites (TPS-1, TPS-2, TPS-3, and TPS-4) are obtained, in which the light absorption and evaporation properties of TPS-3 are the optimal, with an evaporation rate up to 2.451 kg m−2 h−1 and a photothermal conversion efficiency up to 84.74 %. Additionally, the TPS-3 evaporator has excellent stability and salt tolerance, maintaining more than 95.5 % of its original evaporation rate after 20 days of cycling tests. Due to its exceptional photothermal evaporation performance, TPS-3 shows potential for practical commercial applications, particularly in the fields of wastewater treatment and desalination.

Unraveling the residual sludge-mediated waste transformation and physiological regulation mechanism of Tetradesmus obliquus

The accumulation of residual sludge as process waste from water treatment engineering needs to be addressed urgently. Tetradesmus obliquus is an important algal species in the field of wastewater treatment. In this study, T. obliquus was cultured in different sludge extract to determine its ability to utilize wastes from the liquid phase and convert them into biomass, and to analyze the response of the microalgae to toxic stress using proteomics. The results showed that the sludge extract medium was superior to the BG11 medium in accumulating biomass, with dry weights, proteins and polysaccharides at least 1.09, 1.12 and 1.28 times higher than those of BG11 medium. In toxic group, T. obliquus reduced TOC from an initial 426.8±20.0 mg/L to 180.4±8.5 mg/L with a simultaneous 48.4 % reduction in toxicity. Toxic sludge extract produced greater damage to the photosystem of T. obliquus compared to the blank, significantly inhibiting the expression of two photosystem II core proteins, A0A383VSL5 (0.290 down) and A0A383V2Z3 (0.308 down), on day 5. However, these impairments were reversible, and at day 20, the expression of A0A383VSL5 was not inhibited, the inhibitory effect of A0A383V2Z3 (0.575 down) was attenuated. These results fill a gap on the treatment of various types of residual sludge by T. obliquus and provide promising strategies for microalgae treatment of residual sludge, whether non-toxic or toxic.

A Review on Bioflocculant-Synthesized Copper Nanoparticles: Characterization and Application in Wastewater Treatment.

Copper nanoparticles (CuNPs) are tiny materials with special features such as high electric conductivity, catalytic activity, antimicrobial activity, and optical activity. Published reports demonstrate their utilization in various fields, including biomedical, agricultural, environmental, wastewater treatment, and sensor fields. CuNPs can be produced utilizing traditional procedures; nevertheless, such procedures have restrictions like excessive consumption of energy, low production yields, and the utilization of detrimental substances. Thus, the adoption of environmentally approachable "green" approaches for copper nanoparticle synthesis is gaining popularity. These approaches involve employing plants, bacteria, and fungi. Nonetheless, there is a scarcity of data regarding the application of microbial bioflocculants in the synthesis of copper NPs. Therefore, this review emphasizes copper NP production using microbial flocculants, which offer economic benefits and are sustainable and harmless. The review also provides a characterization of the synthesized copper nanoparticles, employing numerous analytical tools to determine their compositional, morphological, and topographical features. It focuses on scientific advances from January 2015 to December 2023 and emphasizes the use of synthesized copper NPs in wastewater treatment.

Microwave-Assisted Synthesis of CdS-MOF MIL-101 (Fe) Composite: Characterization and Photocatalytic Performance.

The present study outlines the synthesis of cadmium sulfide-metal-organic framework (CdS-MOF) MIL-101 (Fe) heterojunctions achieved via fast microwave-assisted reactions. Thus, different CdS-MOF MIL-101 (Fe) ratios were prepared to study their effectiveness as photocatalysts. These compounds were employed in the photocatalytic degradation of methylene blue (MB) under UV and visible irradiation. Structural, morphological, textural, compositional, and optical properties of the synthesized compounds determined by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), UV-vis spectroscopy, Raman spectroscopy, and Fourier transform infrared (FTIR) spectroscopy were utilized to characterize the structural, morphological, textural, compositional, and optical properties. Electrochemical impedance spectroscopy (EIS) was also employed to determine photovoltage and photocurrent densities. The resulting valence band offset (Vfb) and band gap energy values were utilized to construct an energy band scheme. Our research revealed that the CdS-MOF MIL-101 (Fe) heterojunction enhances the efficiency of electron-hole pair separation, thereby mitigating charge carrier recombination effects. Moreover, the type I electronic band structure established an efficient reaction mechanism, effectively suppressing the recombination of photogenerated electron-hole pairs. The photocatalytic system demonstrated exceptional behavior, achieving complete MB removal within 30 min of reaction time and exhibiting outstanding stability and reusability after four reaction cycles. These findings highlight the potential of the synthesized compounds in the field of wastewater treatment for organic pollutants, offering a promising alternative to current environmental issues.

Hysteresis response of carbon release and nitrate reduction in polymer denitrification systems

Polymer denitrification has received much attention in the field of advanced wastewater treatment. It can release carbon source stably during long-term operation, which can be used as electron donor for denitrification. However, the response of the polymer denitrification system to the transient changes of nitrate is not sufficiently disclosed yet. In this study, the response of a polymer denitrification system to nitrate was comprehensively investigated through a series of experiments. Therefore, real-time response and hysteresis response phenomena were identified. The time dependence of microorganisms in the system and the recovery of the hysteresis response were elucidated. The experimental results revealed distinct response patterns before and after the hysteresis tipping point. The denitrifying microorganisms, which showed a high adaptive capacity, exhibited a real-time response over a range of low nitrate concentration variations (∼20–30 mg/L). In contrast, microbial recovery is poor over a range of high nitrate concentration variation (∼35–40 mg/L), which is referred to as a hysteresis response. Finally, the hysteresis response mechanism was revealed by monitoring the recovery of denitrification enzymes, gene and microbial communities. The results showed that transient shocks of high nitrate loads affect microbial community structure stability, denitrifying enzyme activity and gene expression. Meanwhile, the abundance of Microbacterium associated with carbon release was reduced. The combination of these factors leads to a hysteresis response in denitrification and carbon release. This work contributes to a deeper understanding of the hysteresis behavior in polymer denitrification systems, offering critical insights for optimizing system performance and improving nitrogen removal efficiency.

APPLICATION OF INNOVATIVE TECHNOLOGIES IN THE FIELD OF WASTEWATER TREATMENT: FOREIGN AND KAZAKHSTANI EXPERIENCE

The article discusses modern innovative technologies used in the field of wastewater treatment. Special attention is paid to the principles of operation, advantages and applications of technologies such as membrane bioreactors, anaerobic reactors, aerobic granular precipitation, photocatalytic and electrochemical purification, as well as bio- and nanofiltration. The analysis of the experience of the implementation of these technologies in various countries, including successful cases demonstrating the improvement of the quality of water resources and increasing the efficiency of water treatment systems. The experience of Kazakhstan is considered separately, where the use of advanced wastewater treatment methods is becoming an important element of environmental safety. A comparative analysis of the effectiveness of the use of technologies in Kazakhstan and abroad is carried out, the main factors influencing the success of their implementation in the country are highlighted.

Prediction of Biochar Adsorption of Uranium in Wastewater and Inversion of Key Influencing Parameters Based on Ensemble Learning.

With the rapid development of industrialization, the problem of heavy metal wastewater treatment has become increasingly serious, posing a serious threat to the environment and human health. Biochar shows great potential for application in the field of wastewater treatment; however, biochars prepared from different biomass sources and experimental conditions have different physicochemical properties, resulting in differences in their adsorption capacity for uranium, which limits their wide application in wastewater treatment. Therefore, there is an urgent need to deeply explore and optimize the key parameter settings of biochar to significantly improve its adsorption capacity. This paper combines the nonlinear mapping capability of SCN and the ensemble learning advantage of the Adaboost algorithm based on existing experimental data on wastewater treatment. The accuracy of the model is evaluated by metrics such as coefficient of determination (R2) and error rate. It was found that the Adaboost-SCN model showed significant advantages in terms of prediction accuracy, precision, model stability and generalization ability compared to the SCN model alone. In order to further improve the performance of the model, this paper combined Adaboost-SCN with maximum information coefficient (MIC), random forest (RF) and energy valley optimizer (EVO) feature selection methods to construct three models, namely, MIC-Adaboost-SCN, RF-Adaboost-SCN and EVO-Adaboost-SCN. The results show that the prediction model with added feature selection is significantly better than the Adaboost-SCN model without feature selection in each evaluation index, and EVO has the most significant effect on feature selection. Finally, the correlation between biochar adsorption properties and production parameters was discussed through the inversion study of key parameters, and optimal parameter intervals were proposed to improve the adsorption properties. Providing strong support for the wide application of biochar in the field of wastewater treatment helps to solve the urgent environmental problem of heavy metal wastewater treatment.

3D-printed controllable bio-accelerators with sustained release property to boost chromium (VI) inhibited denitrification recovery

Although soluble bio-accelerators have proven effective in mitigating Cr(VI) inhibition within denitrification system, issues persist in immobilizing bio-accelerators and making them slow-release for sustained regulation. In this study, a novel strategy was proposed to fabricate immobilized bio-accelerators with controlled structure, sustained release property by 3D printing technology. Notably, the sustained release of bio-accelerators from 3D-printed bio-accelerators (3DP-B) lasted for at least 144 h. Compared to control group, 3DP-B with basic components (3DP-BB) shortened the recovery time by 1.4 folds, and the COD and NO3--N removal efficiency was 36.5 % and 38.0 % higher than that of natural recovery. Correspondingly, the activity of key enzymes (nitrate reductase, nitrite reductase, nitric oxide reductase, and nitrous oxide reductase), electron transfer system activity and extracellular polymer substances of denitrification biofilm maintained at relatively high levels. Furthermore, introducing 60 mg·L-1 anthraquinone-2,6-disulfonate (AQDS) into the ink showed noticeable superiority on the bio-inhibition release over 1000 mg·L-1 AQDS. The released AQDS facilitated the electron transport capacity by 1.25 times compared with control group. The groundbreaking findings of this study could advance the development of 3D printing technology and utilization of bio-accelerators in the field of wastewater treatment.

A review of advancements in humic acid removal: Insights into adsorption techniques and hybrid solutions

Humic acid (HA) is a prominent contaminant in wastewater, and its elimination is crucial to ensure purified drinking water. A variety of sources of HA in wastewater exist, ranging from agricultural runoff, industrial discharges, and natural decomposition. Adsorption is a technique that has been heavily investigated in this direction. The process complexities, technological advancements, and sustainable approaches are discussed in this review. A range of adsorbents can be employed for HA removal, including modified membranes, carbon nanotubes (CNTs), clay nanoparticles, and acid-modified natural materials. This work compares the effectiveness of the preceding adsorbents along with their advantages and limitations. This review also discusses the optimization of various process parameters, such as pH, ionic strength, and temperature, with an emphasis on response surface methodology for process optimization. Furthermore, the challenges and limitations associated with each removal technique are discussed, along with the potential areas for improvement and future directions in the field of wastewater treatment.