Water Treatment Processes Research Articles

Innovation of poly(ionic liquid)-stabilized TiO2 for membrane-based dye waste remediation

Organic–inorganic nanohybrids based membrane materials are reported for separation applications. In the present study, poly(ionic liquid)-stabilized TiO2/polysulfone-based mixed matrix membranes are produced using a phase separation technique induced by a nonsolvent. The presence of PIL-stabilized TiO2 nanohybrids and the hydrophilic nature of PIL enhance the overall hydrophilicity of the PSf membrane, reaching an impressive water flux of 158 LMH at an operating pressure of 6 bar. Further, membranes were characterized through, Field emission scanning electron microscopy, X-ray diffraction, Atomic force microscopy, Thermogravimetry, and Zeta potential. The synergistic effect of positively charged PIL and TiO2 nanohybrids enhances the membrane's anionic dye retention capability, achieving retention rates of nearly 90.83% for Methyl Blue, 94.28% for Congo red, 65.89% for Evan's blue, and 30.98% for Methyl orange with respect to dye size. However hydrophilic membrane showed outstanding antifouling property of the M2 membrane achieved ∼77% of flux recovery ratio with minimal of ∼37% total fouling for 1000 ppm of Bovine Serum Albumin as a foulant. Highly efficient nanocomposite membranes exhibit significant potential for dye removal and addressing water contamination issues, making them attractive solutions for sustainable fouling resilient water treatment processes.

Hygienic regulation of harmful chemicals in water – a view through the prism of research by the A.N. Sysin Research Institute

The article is devoted to the history of hygienic regulation of harmful chemicals in water at the A.N. Sysin Research Institute, spanning several decades. The article details the stages of the development of the methodology for hygienic regulation of chemicals in water, starting from the first regulatory documents developed under the guidance of A.N. Sysin in the 1940s to an improved methodology that includes accelerated and in-depth toxicological experiments. The developed step-by-step regulation scheme for chemicals in water combines the experimental method of substantiating maximum allowable concentrations (MACs) based on organoleptic and general sanitary indicators of harmfulness with techniques that allow reducing the duration of toxicological studies where it is possible without loss of quality of the results. There are considered modern approaches to predicting the toxicity of substances and their biotransformation, including the use of data mining methods and quantum chemistry. Special attention is given to studying the issues of ensuring safe water use conditions for the population, the application of new chemical compounds in various industries, as well as the effectiveness and safety of reagents and technologies used in water purification and water treatment processes, including improving criteria and methods for studying the combined effects of substances. The results of studies on the transformation processes of substances under the action of various disinfecting agents are presented. Many years of research by the Institute’s staff are reflected in the Methodological Guidelines for substantiating hygienic standards for chemicals in the water of household and drinking water bodies and recreational water use, Methodological Guidelines for assessing the safety of materials, reagents, and equipment used for water purification and treatment, and the development of hygienic standards for the content of chemicals in water. On this basis, modern main documents on the regulation of chemicals in the environment have been created.

Has lake brownification ceased? Stabilization, re-browning, and other factors associated with dissolved organic matter trends in eastern Canadian lakes

The increase in dissolved organic carbon (DOC) concentrations in freshwater systems has received considerable attention due to its implications for drinking water treatment and numerous limnological processes. While past studies have documented the influence of recovery from acidification and climate change on long-term DOC trends, the emerging importance of these explanatory factors remains less understood. In addition, few studies have followed up on recent trends in sites that have undergone increases in DOC. Using a dataset from 1980 to 2020, we investigated interannual variations in DOC and dissolved organic nitrogen (DON) in 49 lakes across four eastern Canadian regions with a history of increases in DOC. We identified recent shifts in DOC patterns using LOESS smoothing and piecewise regression. We observed a stabilizing pattern or even a decrease (p < 0.001) in high acidification regions (Dorset and Nova Scotia), where increases in DOC were previously documented. At the low acid deposition region, IISD-Experimental Lakes Area, an increasing pattern in DOC stabilized in the early 2000s; however, DOC appears to be increasing again in recent years (p = 0.03). Our analysis identified precipitation and SO4 deposition as the primary explanatory variables for DOC patterns (explaining 56–71% of variance). However, because acid deposition has declined substantially, climate and local watershed factors are becoming increasingly influential, leading to the emergence of new DOC patterns. Long-term changes in DOC and DON were not always synchronous, as these were often correlated with different factors (e.g., DON with ammonium deposition). This resulted in observable shifts in DOC:DON ratios, indicative of changes in dissolved organic matter (DOM) composition. We underscore the importance of ongoing monitoring in diverse regions because of the changing nature of environmental variables and new emerging trends.

High Strength Anhydrite Cement Based on Lime Mud From Water Treatment Process: One Step Synthesis in Water Environment, Characterization and Technological Parameters

ABSTRACTIn the process of water treatment from surface water sources, lime mud as waste is formed. This waste contains CaO, Ca(OH)2, and CaCO3. The article proposes a comprehensive method for processing lime mud into high‐strength anhydrite cement. The method involves the interaction of lime mud with waste sulfuric acid from the production of polymer fibers using a structure‐controlled method in the (CaO·Ca(OH)2·CaCO3)—H2SO4—H2O system at a temperature of 40°C. X‐ray diffraction analysis showed the presence of CaSO4 and CaSO4·0.62H2O phases with a purity of 99.8%. The structure‐controlled method makes it possible to control the formation and growth of calcium sulfate crystals of the required shape and size, due to which it is possible to obtain anhydrite cement with desired properties. Combined grinding of synthetic anhydrite with activator additives makes it possible to obtain anhydrite cement with a strength of up to 28.5 MPa.

Microplastic fragmentation into nanoplastics by water shear forces during wastewater treatment: Mechanical insights and theoretical analysis

Nanoplastics (NPs) are generated from the fragmentation of microplastics (MPs) through mechanical forces such as mixing, sonication and homogenization in wastewater treatment plants (WWTPs). Despite their environmental significance, the formation mechanisms and size distribution of NPs in WWTPs are not well understood. This study presents an in-depth investigation into the fragmentation mechanisms of polyethylene (PE) and polystyrene (PS) MPs, sized 250 μm and 106 μm, under simulated WWTP conditions. Our findings demonstrate that under water shear forces ranging from 32 to 100 kJ/L weathered PS and PE particles were further disintegrated into nano-sized particles. Nanoparticle tracking analysis results revealed a significant increase in NP numbers from 8.34 × 10⁸ to 1.54 × 101⁰ NPs/mL as the water shear force increased from 32 to 100 kJ/L. Notably, the smallest NP, measuring 54.2 nm, was produced from 106 μm PS particles at 100 kJ/L. Scanning electron microscope images confirmed micro-cracks on the particle surfaces as the dominant fragmentation mechanism. A robust correlation between experimental NP sizes and theoretical predictions underscores the continuous production of NPs during water treatment processes. These results offer groundbreaking insights into the transformation of MPs within WWTPs and underscore the urgent need for effective strategies to mitigate NP pollution.

Artificial humic acid mediated Fe(II) regeneration to restart Fe(III)/PMS for the degradation of atrazine

The degradation efficiency of organic contaminants using Fenton-like system based on Fe(II) and peroxymonosulfate (PMS) has been hindered by the rapid transformation from Fe(II) to Fe(III) and the slow regeneration of Fe(II). To address this challenge, artificial humic acid (AHA) derived from biomass was incorporated into Fe(III)/PMS system to build AHA/Fe(III)/PMS system. The results demonstrated that the degradation rate of atrazine (ATZ) in AHA/Fe(III)/PMS system (98.83%) is significantly superior to those in Fe(III)/PMS (16.51%) and AHA/PMS system (41.76%) within 90 min. Furthermore, Fe(II) measurement experiments revealed that AHA exhibited more significant iron-reducing potential. The analysis of FTIR, 3D-EEM, and liquid NMR indicated that AHA possessed more structures with reductive potential in comparison to commercial humic acid (CHA) and humic acid extracted from lignite (LHA). The results of persistent free radicals indicated that CHA possessed oxidative potential, which also accounted for the lowest Fe(II) concentration in those system containing CHA. Furthermore, quenching experiments, EPR analysis, and PMSO probe analysis have indicated the presence of reactive species such as •OH, SO4•-, and Fe(IV) within AHA/Fe(III)/PMS system. The degradation products from ATZ were identified and determined to exhibit reduced toxicity relative to parent compound. Collectively, these findings presented an in-depth understanding to reactivate Fe(III)/PMS system, offering a promising alternative strategy for efficient degradation of organic pollutants in water treatment processes.

DNA-labeled chitosan nanoparticles: A potential new surrogate for assessing rotavirus attenuation and transport in sand filtration water treatment

Despite being a model in waterborne risk assessment, rotavirus attenuation and transport in sand filtration water treatment remains poorly understood due to a lack of representative surrogates. We investigated the suitability of DNA-labeled chitosan nanoparticles (DCNPs) to mimic rotavirus attenuation and transport in coastal and alluvial sands. Chitosan nanoparticles were synthesized and coupled with a DNA tracer. Compared to rotavirus, DCNPs had similar size (79 ± 7.2 nm vs. 72.5 nm) and buoyant density (1.65 ± 0.07 g/cm³ vs. 1.36–1.40 g/cm³) but a less negative zeta potential (−20.61 ± 1.94 mV vs. −29.77 ± 0.86 mV) and lower hydrophobicity (0% vs. 44%). Filtration experiments (flow rate 1.26–1.27 ml/min, pH 6.0, electrical conductivity 224–226 μs/cm) showed that DCNPs approximated rotavirus attenuation in coastal and alluvial sands (p ≥ 0.07). Repeated dosing of rotavirus and DCNPs caused removal efficiencies to decline in the sand media. Both entities displayed faster and less dispersive transport than a nonreactive solute tracer (NaCl) in sand media. This preliminary study suggested that DCNPs can approximately mimic rotavirus attenuation and transport in coastal and alluvial sands. However, further validation under diverse experimental conditions is necessary. This includes varying flow rates, pH levels, ionic strengths, and the presence of multivalent cations (e.g., Ca2+ and Mg2+) and organic matter. DCNPs, made from a nontoxic, biocompatible, and biodegradable natural biopolymer, hold promise as a safe tool for assessing rotavirus attenuation and transport in sand filtration water treatment and aquifer filtration processes.

Pharmaceutical Removal with Photocatalytically Active Nanocomposite Membranes.

The advancement of pharmaceutical science has resulted in the development of numerous tailor-made compounds, i.e., pharmaceuticals, tuned for specific drug targets. These compounds are often characterized by their low biodegradability and are commonly excreted to a certain extent unchanged from the human body. Due to their low biodegradability, these compounds represent a significant challenge to wastewater treatment plants. Often, these compounds end up in effluents in the environment. With the advancement of membrane technologies and advanced oxidation processes, photocatalysis in particular, a synergistic approach between the two was recognized and embraced. These hybrid advanced water treatment processes are the focus of this review, specifically the removal of pharmaceuticals from water using a combination of a photocatalyst and pressure membrane process, such as reverse osmosis or nanofiltration employing photocatalytic nanocomposite membranes.

Diclofenac sodium removal by powdered activated carbon of coconut endocarp: process optimization, kinetics, and isotherms

ABSTRACT Emerging contaminants (ECs) have been detected in various environmental compartments, particularly aquatic bodies. Diclofenac sodium (DS), one of the most ecotoxic ECs, causes hemodynamic changes, thyroid tumors, and adverse effects under chronic exposure. Therefore, some countries have adopted restrictive legislation, encouraging the development of technology to mitigate this. Among water treatment processes, adsorption is an effective technical and economic alternative. In this context, this study aimed to evaluate, on a bench scale, the efficiency of DS removal in powdered activated carbon (PAC) of coconut endocarp. DS adsorption was analyzed via central composite design (CCD) using four factors: diclofenac sodium concentration (CDS from 50 to 450 mg·L−1 ), adsorbent concentration (CPAC from 0.2 to 5 g·L−1), contact time (Ct from 5 to 45 min), and pH (from 5 to 9). The results supported response modeling for adsorption capacity, pseudo-first-order (PFO) and pseudo-second-order (PSO) kinetics, intraparticle diffusion (IPD), and Langmuir and Freundlich isotherms. DS demonstrated an affinity for adsorption on PAC. The maximum adsorption capacity was 169.39 mg·g-1 for PAC (CDS of 331.64 mg·L−1, CPAC of 0.2 g·L−1, Ct of 40.6 min, and pH 5) obtained through duplicate confirmation batches.

Application of bioflocculants produced by Prestia megaterium for drinking water purification

Quality water is a scarce commodity in the developing countries. This paper aims to evaluate the application of bioflocculants produced by Priestia megaterium (accession number: ON184360) for drinking water purification. A total of twenty-four water samples from stream, ponds and wells were collected in sterile containers from four different Local Government Areas of Niger State, Nigeria. Each sample was treated with varying concentrations of bioflocculant and chemical flocculant (0.05, 0.1, 0.15, 0.2 and 0.5 mg L−1). The microbiological and physicochemical characteristics of the treated and untreated water were determined using standard methods. The results show that water samples from stream, ponds and wells treated with the bioflocculant significantly reduced the microbial load and the physicochemical properties of the water reduced to an acceptable limit, which has practical significance for the safety of drinking water in developing countries. The bioflocculant was effective in aggregating suspended particles and thus, proved its potential to be used as alternative flocculant in the drinking water treatment process.

Examining the Potential of Biogas: A Pathway from Post-Fermented Waste into Energy in a Wastewater Treatment Plant

Biogas has improved due to technological advancements, environmental awareness, policy support, and research innovation, making it a more cost-effective and environmentally friendly renewable energy source. The Generalized Linear Model (GLM) was employed to examine the relationship between purchased and generated energy from 2007 to 2023. Metrics such as deviance, log likelihood, and dispersion phi were examined to assess model fit. The Mann–Kendall test was utilized to detect trends in energy datasets. Biochemical Oxygen Demand (BOD5) and Chemical Oxygen Demand (COD) reduction was significant, exceeding 97% from 2014 to 2023. However, treated sewage displayed limited susceptibility to biological degradation, with COD to BOD5 ratios increasing from 2.28 to 6.59 for raw sewage and from 2.33 to 7.05 for treated sewage by 2023. Additionally, the efficiency of sewage purification processes was calculated, and multivariate regression analysis was conducted on gas composition data. Principal Coordinate Ordination (PCO) and k-means clustering were used for dimensionality reduction and biogas component clustering, respectively. This research showed that biogas from the waste water treatment process can be used, particularly in methane production. Technological advancements have made biogas production more efficient, enhancing energy generation within a circular economy framework.

Time series-based machine learning for forecasting multivariate water quality in full-scale drinking water treatment with various reagent dosages

Accurately predicting drinking water quality is critical for intelligent water supply management and for maintaining the stability and efficiency of water treatment processes. This study presents an optimized time series machine learning approach for accurately predicting multivariate drinking water quality, explicitly considering the time-dependent effects of reagent dosing. By leveraging data from a full-scale treatment plant, we constructed feature-engineered time series datasets incorporating influent water quality parameters, reagent dosages and effluent water characteristics. Seven predictive models, including both traditional machine learning (ML) and deep learning (DL) models were developed and rigorously evaluated against a naive mean baseline model. Our results demonstrate that traditional ML models, enhanced with time feature engineering, rivaled the performance of both widely used DL models and the naive mean baseline model. Specifically, an XGBoost model achieved superior prediction accuracy in dynamically forecasting four water quality characteristics at a 12-hour time lag step, outperforming the naive baseline model by 3–4 % in terms of Mean Absolute Percentage Error (MAPE). This finding underscores the importance of incorporating a 12-hour interval to effectively capture the delayed impact of reagent dosing on water quality prediction. Furthermore, SHAP model interpretability analysis provided valuable insights into the XGBoost model's decision-making process, revealing its strong data-driven foundation aligned with established water treatment principles. This research highlights the significant potential of optimized machine learning techniques for enhancing water purification processes and enabling more informed, data-driven decision-making in the water supply industry.

Enhanced electrochemical degradation of per- and polyfluoroalkyl substances (PFAS) by activating persulfate on boron-doped diamond (BDD) anode

Per- and polyfluoroalkyl substances (PFAS) remediation remains a challenge, especially for real samples such as aqueous film-forming foams (AFFF) for fire-fighting and PFAS foam fractionate concentrates (FF) produced from the water treatment processes. In this study, electrochemical advanced oxidation process (EAOP) using boron-doped diamond (BDD) anode to activate persulfate (PS) was investigated. The results shown that the electrochemical activation of PS significantly enhanced the removal of PFAS, including oxidation and defluorination. Under the optimal conditions (initial current density of 40 mA/cm2, 5 mM PS, initial pH 3.8), both 50 μM PFOA and 50 μM PFOS reached ∼100 % removal within 2 h, and 60.4 % and 33.1 % defluorination, respectively. By monitoring the degradation intermediates, the degradation pathways and kinetics of PFOA and PFOS were studied, which indicated the excellent capability of BDD/PS process towards the PFAS remediation. In addition, the optimal BDD/PS process was applied to degrade AFFF and FF samples, and the total oxidizable precursor (TOP) assay was used to measure the defluorination effect. The results were unprecedented with a surprising >100 % defluorination for 28 PFAS tested. This research can contribute to the development of a sustainable and efficient technology for PFAS remediation, ultimately mitigating the environmental and health risks associated with these persistent contaminants.

Non-Targeted Screening and Identification of the Transformation Pathway of Carbamazepine in the Saemangeum Watershed, Republic of Korea.

Carbamazepine (CBZ) is a widely used pharmaceutical for various purposes, including as an anticonvulsant, antibiotic, and antiepileptic agent, and it undergoes diverse metabolic pathways in both the environment and the human body. Therefore, this study aimed to explore the distribution of CBZ, the presence of its transformation products (TPs), and the transformation pathways in the Mangyeong and Dongjin Rivers in the Saemangeum watershed of Korea using non-targeted screening. The concentration distribution results for CBZ and its TPs showed that the average concentrations in the Mangyeong and Dongjin Rivers were 128.8 ng/L and 89.0 ng/L, respectively. The Mangyeong River exhibited a higher CBZ concentration than the Dongjin River, which was similar to those of the reported CBZ concentrations in other major domestic and international rivers. The types and detection frequencies of the identified TPs exhibited similar trends. The detection frequencies of the TPs decreased in the following order: CBZ-EP > DiOH-CBZ > 10OH-CBZ > 2OH-CBZ > 9-carboxyacridine > 9-acridinecarboxaldehyde. The detection frequency of the main TPs was high, and some were believed to be generated during the water treatment process. The presence of additional TPs (CBZ-O-quinone, acridine, and iminostilbene) was confirmed by the generated molecular networks. This study presents the transformation pathway of the CBZ and provides foundational data for understanding the environmental behavior of TPs, improving wastewater treatment plants, managing water quality, and establishing water environmental policies.

Experimental Study on the Optimization of an Integrated Treatment Process for Micro-polluted Surface Water by Response Surface Methodology

Experimental Study on the Optimization of an Integrated Treatment Process for Micro-polluted Surface Water by Response Surface Methodology

Standardization of FTIR-Based Methodologies for Microplastics Detection in Drinking Water: A Meta-Analysis Indeed and Practical Approach

The detection of microplastics (MPs) in drinking water presents significant environmental and public health challenges. This study comprises two stages: a meta-analysis aimed at standardizing Fourier Transform Infrared Spectroscopy (FTIR) methods for MP detection, followed by the practical implementation of these findings in the laboratory. The review of studies conducted from 2019 to 2023 identifies 0.45 μm cellulose nitrate filters and Nile red staining as the most effective techniques for fluorescent detection. Experimental results demonstrate the superior retention capabilities of cellulose nitrate filters and the uniformity of Nile red staining. This dual approach not only optimizes water treatment processes but also enhances the accuracy of MP detection. The findings contribute to improved water quality management and public health protection by establishing robust protocols for MP analysis.

Stepwise increasing TMC concentration in NF membranes fabrication for controlled PA layer thickness, compactness, and charge distribution: Maintaining high permeance, enhancing desalination, and mechanistic insights

Piperazine (PIP)-based polyamide (PA) nanofiltration (NF) membranes exhibit limited rejection of divalent cations due to their negatively charged surfaces and insufficient compactness, restricting their broader application in various water treatment processes. To overcome this challenge, a novel strategy—stepwise increasing TMC concentration (SITC) during the interfacial polymerization (IP)—was proposed to optimize the PA layer structure. Conventional PA layer demonstrates a vertical diffusion structure: a compact barrier region underneath a thick and loose region. The regulatory goal of SITC is to enhance compactness while minimizing the increase in hydraulic resistance. The regulatory mechanism suggested SITC could regulate the IP reaction in both over time (throughout the IP process) and across the reaction region. During the initial IP stage, SITC reduced the reaction rate and increased PIP/TMC ratio in the bottom reaction zone, thereby improving the compactness and potential of final bottom barrier region. Thus, SITC can effectively restrict the permeation of cations, significantly increasing MgCl2 rejection from 33.70 % to 92.12 %. In the subsequent diffusion-limited stage, SITC enhanced the restriction on PIP diffusion, decreasing the thickness of the final upper loose region and surface potential. Those advantageous characteristics allowed the membrane to maintain a high rejection for Na2SO4 (>98.44 %). Concurrently, the membrane maintained a high water permeance (13.00 L·m−2·h−1·bar−1), attributed to the thin (16.69 nm) and optimized compactness distribution of its PA layer. This study provided a novel mechanism insight into the functional customization of NF membranes by decoupling the synthesis-property-performance relationship.

Luminescent iron phthalocyanine organic polymer nanosheets with space-separated dual-active sites for the detection and photocatalytic reduction of Cr(Ⅵ) from wastewater

Cr(Ⅵ) residues in livestock and poultry wastewater are a rising concern for human health and biotic environments. For the removal of Cr(Ⅵ), its simultaneous reduction and adsorption represents a sustainable and efficient strategy. Herein, iron nodes on covalently bonded two-dimensional phthalocyanine organic polymer (PcOP-Fe) nanosheets with space-separated dual-active sites are developed for the simultaneous detection and removal of Cr(VI) from wastewater. In the FeN4 structure of PcOP-Fe nanosheets, Fe acts as an electron capture center, effectively facilitating the accumulation of photogenerated electrons and transferring them to Cr(VI), thereby achieving its photocatalytic reduction. Meanwhile, pyrrolic nitrogen provides excellent adsorption sites, enabling the adsorption of Cr(III) or Cr(0). Fe accumulates the photogenerated electrons from pyrrole N and transfer them to Cr(Ⅵ). The formation of N-Cr(Ⅲ) bonds causes a space-separation between Cr(Ⅵ) and Cr(III). In addition, PcOP-Fe can be used for a Cr(Ⅵ) detection agent. The photoluminescence intensity decreases linearly with increasing Cr(Ⅵ) concentration from 80 μM to 2 mM, with a limit of detection of 0.18 μM. The PcOP-Fe nanosheets exhibit good Cr(Ⅵ) detection and reduction performance in livestock and poultry wastewater, suggesting their suitability for practical sensing applications. Thus, the PcOP-Fe nanosheets with space-separated dual-active sites are promising for the simultaneous detection and removal of Cr(Ⅵ) in water treatment processes.

Study on the hydrolysis characteristics of polymeric aluminum chloride forced by fine bubbles and its key factors affecting the efficiency and capacity of forcing hydrolysis

Enhanced coagulation is an important way to remove natural organic matter and reduce disinfection by-products in traditional water treatment processes, in which the micromolecular organic matter that is difficult to be removed during conventional coagulation can be enhanced more conveniently by modulating the dominant Al species in the traditional metal salt coagulants (e.g., polymeric aluminum chloride, PACl). Based on the forcing hydrolysis characteristics of fine bubbles due to the adsorption of hydroxide ions on their surfaces, this study verified the adaptability of the forced PACl hydrolysis by fine bubbles under different operating conditions objectively and comprehensively. The morphological changes of PACl before and after forced hydrolysis by fine bubbles were characterized figuratively, and the evolution of the dominant Al species before and after forced hydrolysis by fine bubbles was reasonably elaborated. The experimental results showed that fine bubbles had the effect of forcing the hydrolysis of PACl with different degrees of alkalinity and modulating the dominant Al species. It was innovatively found that the mass transfer efficiency of the fine bubbles determined their efficiency in forcing PACl hydrolysis (Pearson's r = -0.9423) and the concentration of fine bubbles affected their capacity to force PACl hydrolysis (Pearson's r = 0.8189). At pH = 7 and an air flow rate of 20 mL/min, the DOC concentration of micromolecular organics and the DOC removal efficiency of total organics could be reduced by 0.54 mg/L and enhanced by 12.6 %, respectively, after forced PACl hydrolysis by fine bubbles. While deepening the mechanism of forced PACl hydrolysis by fine bubbles, the above results preliminarily verified the relevance and feasibility of modulating the dominant Al species through forced PACl hydrolysis by fine bubbles to improve the coagulation efficiency, which provided theoretical and data support for the construction of a fine bubble-enhanced coagulation process for drinking water treatment plants.

Mathematical model of dissolved microbial products in sewage treatment system

Water is the source of life, but all kinds of water resources in the world are suffering from different degrees of pollution. Water pollution leads to a serious shortage of available fresh water resources, and sewage treatment is the main way to solve water pollution. For the sewage after biological treatment of activated sludge, the organic matter contained in the effluent is mainly the dissolved microbial products (SMPs) produced in the process of microbial metabolism. The composition of SMPs is complex, mainly including macromolecular substances such as protein, polysaccharide, humic acid and DNA and cell fragments. The mathematical model of activated sludge is a quantitative description of the mathematical relationship between substrate degradation parameters and microbial growth. Starting from the Monod equation representing the relationship between substrate consumption and microbial growth, it combines the reactor theory and microbiology theory in the chemical field. Based on the principle of conservation of materials and Monod equation, the mathematical expression of organic degradation model was determined according to the collected data and empirical values of parameters. The general idea of activated sludge model No.1 (ASM1) for activated sludge process simulation was introduced, and the influence of sludge concentration on SBR process water treatment was explored. It was found that the removal rate of COD, ammonia nitrogen, total nitrogen and total phosphorus increases with the increase of sludge concentration. When C/N=8, the removal rate of ammonia nitrogen increased from 62% to 81%, and the removal rate of total nitrogen increased from 64% to 82%, with the most obvious effect.