Organic Removal Research Articles

Comparative analysis of hospital laboratory wastewater treatment techniques in Syrian Arab Republic

Background: Hospital wastewater poses a significant threat to human health due to the presence of difficult-to-degrade organic compounds, active pharmaceutical ingredients and multiple inorganic substances that can pollute water resources and ecosystems. Aim: To compare the effectiveness of different techniques for removing organic load from hospital laboratory wastewater in Aleppo, Syria. Methods: We treated wastewater samples from hospital laboratories at Aleppo University Hospital, Syria, using several techniques, including biological treatment with the rotating biological contactor, adsorption with Syrian natural clay, coagulation with aluminium sulphate, advanced oxidation with ultrasound, and a combined treatment using natural clay and ultrasound. We assessed the organic load removal efficiency for each technique under different conditions. Results: The most effective technique was the combination of natural clay and ultrasound. Applying natural clay at a concentration of 1 g/L of wastewater along with ultrasound at 40 kHz for 30 minutes achieved chemical oxygen demand and biochemical oxygen demand values suitable for irrigation, in accordance with the Syrian standard. The chemical oxygen demand value decreased to 212 mg/L with 94% removal rate, and the biochemical oxygen demand value decreased to 82 mg/L with 87% removal rate. Conclusion: Based on our findings, techniques that combine different methods of hospital wastewater treatment, such as combining adsorption with advanced methods like ultrasound, are more effective than those that use single methods. Such techniques should be promoted.

Algae Removal and Release of Algal Organic Matter During Ozonation of Synechococcus sp.

Pre-ozonation can enhance the removal of algae in source water during cyanobacterial blooms; however, little is known about the influence of the co-existing allochthonous natural organic matter (NOM) on algal removal and algal organic matter (AOM) behavior during ozonation. This study aims to elucidate in the presence and absence of allochthonous NOM and the effects of varying ozone doses on Synechococcus sp. cell removal, membrane integrity, and dissolved organic matter (DOM) release and removal. The results indicate that ozone effectively disrupted algal cell membranes, reducing algal density; however, the presence of allochthonous NOM delayed cell rupture by competing for ozone due to aromatic humic-like substances. Pterin-like and protein-like fluorescent compounds were released upon cell disruption. Due to that, excess ozone led to the oxidation of the released pterin-like compounds, with characteristic fluorescence changes correlating to ozone dosage; these changes are potential to be used as an indicator to determine the optimized ozone dosage, avoiding more adverse release of intracellular AOM to form disinfection byproducts.

Dye-sensitized n-n heterojunction {001}TiO2@NH2-MIL-101(Fe) for degradation of rhodamine B under visible light

The {001}TiO2@NH2-MIL-101(Fe) heterojunctions (MT-x) crafted by the fusion of components {001}TiO2 and NH2-MIL-101(Fe) possesses an optimally positioned conduction band. Consequently, MT-x is capable of sensitizing Rhodamine B (RhB) and effectuating its degradation via a photocatalytic mechanism that is driven by visible light irradiation. Specifically, the n-n heterojunction designated as MT-3 achieved a RhB removal rate of 94.45 % within a 3-hour period, which corresponds to a 5.4-fold and 2.2-fold enhancement over the degradation rates observed for {001}TiO2 and NH2-MIL-101(Fe), respectively. Photo-electrocatalytic performance analyses showed that the n-n heterojunction MT-3 effectively inhibited electron-hole pair recombination. Moreover, the intimate interfacial contact between monomer materials enhanced the separation and transfer of photogenerated carriers, which indicates that MT-3 has excellent photocatalytic performance. The free radical trapping and EPR results indicated that ·O2- plays a major role in the photocatalytic degradation of RhB by MT-3, followed by h+ and ·OH. Furthermore, high-resolution liquid chromatography-mass spectrometry was employed to investigate photodegradation intermediates. The destruction of the RhB structure significantly reduced the environmental pollution associated with organic dye. The MT-x heterojunction exhibits remarkable potential for practical applications in organic contaminants removal.

Organics removal from a hypersaline wastewater in epichlorohydrin production via electrochemical oxidation and resin adsorption: Performance and process optimization

Epichlorohydrin (ECH) as a raw material is widely used as an indispensable intermediate in the production of synthetic glycerin and epoxy resin. However, epichlorohydrin wastewater (EW) with high salinity and concentration of organics was generated during ECH production process. In this work, the removal of organics in EW by single electrochemical oxidation (EO), resin adsorption, and their hybrid process were explored. Effects of operating parameters such as current density, time, initial pH on EO and adsorption process were comprehensively optimized by single-factor experimental method. The optimal reaction parameters of combined EO-adsorption process were pinpointed: an initial pH of 4, a current density of 100mA/cm2, a solid-liquid ratio of 1:4 and a temperature of 298.15K. The combined EO-adsorption process achieved an excellent organic removal rate of 90.24%, while reduced the energy consumption and increased current efficiency. Additionally, the results of excitation-emission matrix (EEM) confirmed that the organics was removed efficiently by combined EO-adsorption process. The mechanism of organics removal by EO was elucidated, which mainly reacted with organics by oxidizing active substance produced by anode. The results of adsorption kinetic showed that the adsorption process was suitable for the pseudo-second-order model. The results above demonstrated that the combined EO-adsorption process was a potential technology for organics removal in EW.

Predicting organic matter and nutrient removal efficiency in a constructed wetland using data mining

Vertical and horizontal flow constructed wetlands (VF and HF CWs) are most widely used in the treatment of domestic sewage, storm runoff and selected industrial wastewaters. Current research focuses on the search for new applications, alternative substrates and developing mathematical and statistical methods to model the process of removing pollutants in CWs. This is important from a scientific and practical point of view. The performance of VF CWs with two types of substrate (gravel and Certyd - a waste material) was investigated over a two-year period. The following parameters were analyzed: biological oxygen demand (BOD5), chemical oxygen demand (COD), ammonia nitrogen (N-NH4), total nitrogen (N-Total), total phosphorus (P-Total) and dissolved oxygen (DO). At the same time, both the temperature of the inlet sewage and the air temperature were monitored. A support vector machine with a Gaussian kernel function was used to model the treatment efficiency. To select the model parameters, a 10-fold cross-validation was applied. The models applied were characterized by a very good fit. The expected average efficiency of organic removal was 88.3% (BOD5) and 80.8% (COD) in the bed filled with Certyd, and 83.8% (BOD5) and 76.9% (COD) in the bed with a classic filling. The predicted average efficiency of N-NH4 and N-Total removal in CWs filled with Certyd and gravel were 80.4 and 74.2%, and 59.6% and 57.0% respectively.

Global soil microplastic assessment in different land-use systems is largely determined by the method of analysis: A meta-analysis

Although microplastics (1 μm - 5 mm, MP) are increasingly recognised as a novel entity of pollutants, we still lack a basic understanding of their prevalence in different terrestrial environments. Here, we aimed at performing comparisons of MP concentrations (items kg−1) in different agro-ecosystems, with specific focus on input pathways and land uses, while accounting for the plethora of method variations available, such as analysed MP sizes, sampling depths, density separation solutions, as well as removal of organic matter. We found that the current global means of MP loads, from 89 studies (553 sites), benchmarks 2900 ± 7600 MP items kg−1 soil, substantially more than the global median of 480 MP items kg−1. Roughly 81 % of the studies were conducted in Asia; hence, continent-wider comparisons are still hampered by low study numbers for most regions. Maximum MP numbers were found for soils under both greenhouses and plastic mulching (5200 ± 8300 items kg−1), followed by arable soils with sludge amendments (3700 ± 8800 items kg−1), surprisingly without evidence of elevated MP loads in horticultural fields relative to other agricultural management practices. Intriguingly, global MP loads significantly increased with decreasing levels of urbanisation, i.e., they were highest in rural areas. Yet, quantitative comparisons among sites are biased by the methodology selected for MP analyses. Apart from inconsistencies in sampling depth and size of screened MP particles, across all sites and treatments, largest MP loads were commonly found when using high-density solutions rather than low-density ones, and when soil organic matter removal was performed after and not before the density separation step.

A flexible Ag2S QD sensitized TiO2 Janus photocatalytic nanofiber membrane for visible light organic pollutant degradation and COD removal

A flexible Ag2S QD sensitized TiO2 Janus photocatalytic nanofiber membrane for visible light organic pollutant degradation and COD removal

Uncovering the causal relationships in plant-microbe ecosystems: A time series analysis of the duckweed cultivation system for biomass production and wastewater treatment

The complex interplay among plants, microbes, and the environment strongly affects productivity of vegetation ecosystems; however, determining causal relationships among various factors in these systems remains challenging. To address this issue, this study aimed to evaluate the potential of a data analytical framework called empirical dynamic modeling, which identifies causal links and directions solely from time series data. By cultivating duckweed, a promising aquatic plant for biomass production and wastewater treatment, we obtained a 63-day time series data of plant productivity, microbial community structure, wastewater treatment performance, and environmental factors. We confirmed that empirical dynamic modeling can identify the correct causal directions among temperature, light intensity and plant growth, solely from time series data. Extending the analysis to microbial community data suggested that the bacterial family Comamonadaceae positively affects host duckweed growth and nitrogen removal. Additionally, the predicted abundance of bacterial genes relevant to xenobiotics biodegradation was shown to have a positive effect on organic pollutant removal, supporting the significant role of bacterial metabolism in phytoremediation performance. These results demonstrate the effectiveness of empirical dynamic modeling in uncovering causal relationships within vegetation ecosystems, which are difficult to examine comprehensively through conventional experiment-based approaches.

Biomethane Production Through Performance Enhancement of Anaerobic Digestion and Sludge Dewatering Processes in a Wastewater Treatment Plant

Sewage sludge management poses a persistent challenge due to increasing volumes and stringent environmental regulations. Current municipal wastewater treatment technologies are energy intensive, produce large quantities of residuals and fail to recover the potential resources available in wastewater. Anaerobic digestion (AD) is widely recognized for its cost-effective stabilization, high organic matter removal, and biogas production potential. However, the hydrolysis phase remains a bottleneck in AD, limiting methane yield. Furthermore, its application for low strength municipal wastewater is limited. To address such challenges, the effects of combined microwave-ultrasonic and combined microwaveoxidative pre-treatment of thickened excess activated sludge and mixed sludge on the performance enhancement of conventional mesophilic digester and on two-stage digesters are presented in this study. Microwave-ultrasonic pretreatment was optimized for enhanced cell disruption, while microwave oxidation pretreatment incorporated hydrogen peroxide to generate reactive oxygen species for accelerated organic solubilization. Experimental setups included single- and two-stage anaerobic digesters operated under mesophilic and thermophilic conditions. Results demonstrated that combined microwave-ultrasonic pretreatment improved cumulative methane production by 18% and total solids reduction by 31%, compared to microwave-only pretreatment. Microwave oxidation pretreatment with 1% H₂O₂ achieved 40% volatile solids solubilization, significantly enhancing methane yield and sludge dewaterability. The two-stage AD process further improved performance, achieving 76.4 mL/g TCOD methane yield and 58% methane content in biogas, outperforming single-stage systems. Findings indicate that hybrid pretreatments synergistically enhance hydrolys

Influence of inoculum-to-substrate ratio on biomethane production via anaerobic digestion of biomass.

The influence of the inoculum-to-substrate ratio (ISR) on anaerobic digestion (AD) of biomass in terms ofmethane yield and microbial community, was explored in this paper. The level of ISR can affect the AD performance in several ways. At extremely low ISR, volatile fatty acids (VFAs) accumuate, while inhibition occur at higher level of ISR. An ISR ranging from 1.0-2.0 was found optimal resulting in higher methane yield, organic matter removal and VFA degradation. Furthermore,a high ISR (2.0-4.0) is favourable to methanogenesis, while a lower ISR (<1.0) is prone to irreversible acidification. The range of ISR can shift the methanogenic pathway of AD to favour an acetoclastic or hydrogenotrophic response, indicated by the enriched group of microorganisms. The genus Methanosaeta (acetoclastic) and Methanobacterium (hydrogenotrophic) are the most enriched methanogens across all ISRs, while Firmicutes, Bacteroidetes, Proteobacteria and Spirochaetae are dominantin the bacterial community. Additionally, the interplay of substrate biodegradability and ISR potentially affects AD performance. Finally, novel equations are developed and proposed for characterizing the quantity of inoculum and substrate.

Nanofluid-peroxydisulfate integrated volumetric solar interfacial evaporation system for water evaporation and organic pollutant removal

Solar evaporation exhibits significant potential for the treatment of high-salt organic wastewater. However, it's also confronted with challenges due to the accumulation of organic pollutants and salts in the concentrated wastewater following evaporation, which compromises the long-term stability of evaporation unit and complicates subsequent treatment processes. To address these challenges, a volumetric solar interfacial evaporation (V-SIE) system by integrating Fe3O4-H2O nanofluids and peroxydisulfate (PDS) were proposed in this study. In V-SIE system, Fe3O4 magnetic nanoparticles (NPs) were prepared as solar receivers to form a volume-absorbing solar energy interface and enhance evaporation efficiency. The results show that the evaporation rate was 1.412 kg/(m2·h) and the solar efficiency reached 93.75% as the temperature rose to 57.2 ℃. Additionally, the high thermal conductivity of Fe3O4 facilitated the effective heat transfer to the fluid and provided sufficient thermal energy to activate PDS, thereby removing 99.3% of Rhodamine B (RhB). Fe3O4 NPs effectively promoted the generation of reactive species including SO4•−, •OH, O2•− and 1O2 from PDS and the four main stages including N-de-ethylation, chromophore cleavage, ring-opening, and mineralization were proposed as the possible degradation pathway of RhB. This study provides a reference for developing V-SIE system and highlights the positive effect of nanofluids in advanced oxidation processes.

Stability of a novel integrated photocatalysis-ultrafiltration reactor: Algal organic matter removal and membrane fouling alleviation mechanism

Stability of a novel integrated photocatalysis-ultrafiltration reactor: Algal organic matter removal and membrane fouling alleviation mechanism

Insight into the ferrate(VI)/ozone process: Multiple oxidation systems promote the elimination of electron-deficient pollutants

The utilization of ferrate(VI) (Fe(VI)) is constrained by its limited efficacy in removing electron-deficient pollutants. This study provided insights into the enhanced removal of such pollutants by employing a blend of ozone (O3) and Fe(VI). The removal of electron-deficient pollutants by individual Fe(VI) (50 μM) or O3 (25 μM) ranged from 5 % to 50 % at pH 8.0. The synergistic Fe(VI)/O3 process enhanced the removal to a range of 60 %-95 %, while the pollutants removal rate constant showed a significant increase ranging from 3 to 14 times. The Fe(VI)/O3 process exhibited an increase in total organic carbon removal by 40–90 %. Multiple enhanced oxidation systems were constructed by intermediates derived from the Fe(VI) and O3. The self-decomposition of Fe(VI) released H2O2, which coupled with O3 to form ·OH. Revealed through XPS analysis, the Fe(III) flocs derived from Fe(VI) decomposition contained structures of Fe2O3 and FeOOH. The combined flocs/O3 processes facilitated the production of both ·OH and Fe(IV)/Fe(V). Product analysis and Fukui function calculation demonstrated that, many hydroxylated initial products were exclusively found in the Fe(VI)/O3 process. ·OH initially transforms electron-deficient pollutants into electron-rich products, rendering them more susceptible to electrophilic attack by Fe(IV)/Fe(V). The employment of the Fe(VI)/O3 method demonstrates a concurrent increased production of ·OH and Fe(IV)/Fe(V), presenting a potential resolution for tackling the issue related to stubborn electron-deficient pollutants.

Enhanced degradation and mineralization of OFX in water: Triggering the shift of dominant role from •OH to O2•- in dielectric barrier discharge plasma system

Faced with the threat to water environment posed by non-standard antibiotic usage, enhanced removal and mineralization of ofloxacin (OFX) were achieved concurrently by adding MnFe2O4/MXene to trigger the dominant role of O2•- based on dielectric barrier discharge plasma (DBDP). The electron (e-)-hole (h+) pairs formed by the action of high-energy electrons or photons in DBDP on MnFe2O4/MXene created the majority of the O2•- through catalyzing H2O2 and O2. Besides, multiple advanced oxidation processes (AOPs), Fenton-like reaction and O3 catalysis for example, were also involved in the MnFe2O4/MXene-DBDP system. MXene effectively inhibited the recombination of e--h+ pairs, while also facilitating the charge transfer from Mn/Fe sites to the antibonding orbits of the adsorbed H2O2, O2 and O3. Notably, the predicted serial toxicities of potential intermediates confirmed the necessity of focusing on mineralization efficacy. This study provided a promising alternative for refractory organic pollutant removal and enriched the catalytic mechanism at the micro level.

Degradation of the Antibiotic Sulfamethoxazole by Ozonation: A Comprehensive Review

ABSTRACTSulfamethoxazole (SMX) is an antibiotic widely used for the treatment of several diseases, especially respiratory and urinary. Due to its widespread use, its presence in the environment has been on the rise. This study discusses the degradation of the antibiotic SMX through the ozonation process. SMX is preferentially degraded by the direct action of O3 on the molecule, starting by breaking the double bonds in the aromatic ring. Through ozonation it is possible to obtain complete SMX degradation within 10 min, but the mineralization of the solution is not achieved, reaching total organic carbon removal efficiencies of 5%–60%, depending on the reaction time. Factors such as the presence of organic matter (OM) and the pH of the solution interfere with the degradation of SMX. The OM acts as a radical scavenger, decreasing the efficiency of degradation, while the pH interferes with the decomposition of O3 into radicals and the dissolution of the oxidant in the medium, in addition to influencing the state of ionization of the SMX making it more or less prone to reactions. In general, most other remediation processes are carried out on a laboratory scale. To increase the level of these processes to a full scale, more pilot‐scale studies are needed. In addition, it is necessary to focus on the practice of reusing materials, avoiding the generation of secondary pollution, and increasing the useful life of the material. The review also discusses the reaction mechanisms, intermediate compounds formed, mineralization of the solution, and factors that influence the process, which can help in making decisions for future studies to be carried out in the area. Prospects in the research area revolve around using metal–organic frameworks as molecular imprinting technology to modify heterogeneous catalysts, integration of external energy, bimetallic systems, and evaluation of deactivation mechanisms.

Effect of Different Biomass Levels of Eichhornia crassipes and Pistia stratiotes on Nutrients, Organics, and Heavy Metals Removal from Wastewater

Effect of Different Biomass Levels of Eichhornia crassipes and Pistia stratiotes on Nutrients, Organics, and Heavy Metals Removal from Wastewater

Upgrading the eastern wastewater treatment plant effluent quality in Egypt for reuse by means of in-line coagulation followed by ultrafiltration

ABSTRACT Providing clean water to Egyptian citizens is one target of the 2030 sustainable development goals. Ultrafiltration (UF) has been investigated as an advanced treatment of the largest treatment plant in Alexandria. Although UF membranes have been widely used to treat secondary effluent, fouling remains a major challenge. The effects of green and conventional coagulants on controlling ultrafiltration fouling were examined. Two different dosages of each coagulant and a combination of ferric chloride and sodium ferrate were studied in a bench-scale setup that was built and operated under identical circumstances. The results showed that the combined ferrate and ferric chloride pretreatment had the highest performance in terms of the removal of organics and turbidity as well as the reduction of membrane fouling. Fouling can be managed in terms of the normalized flux drop with only 0.5 mg/L of ferrate, which performs similarly to 2.5 mg/L of ferric chloride. The higher the dosage of alum used, the lesser the fouling control observed. The green coagulant, when used as an in-line coagulant aid/oxidant with ferric chloride at very low doses, has a favorable potential to reduce membrane fouling and improve permeated wastewater quality, making it suitable for Grade A for reuse purposes.

Synthesis, (bio)degradation, and utilization of starch-derived biopolymers in defined hard waters

Climate change is causing a change in local rainfall, which generally brings with it a reduction in rainfall and, consequently, an increase in water hardness. This study explores the suitability and stability of various dextrin-derived polymers for cation removal in simulated hard water conditions. Thermal analysis and Fourier-transform infrared spectroscopy confirm the polymers' thermal stability and proper formation. Biodegradability assessments reveal KLEPTOSE®LINECAPS (LC) and GLUCIDEX2® (Glu2) dextrin with pyromellitic dianhydride (PMDA) derivatives have higher durability as they were able to endure enzymatic activity. Adsorption experiments at 300 and 600 ppm indicate significant variations influenced by monomer and crosslinker types, with linear monomers demonstrating superior performance. Notably, different crosslinkers exhibit varying affinities for calcium and magnesium ions, with PMDA derivatives excelling for magnesium and citric acid (CA) derivatives for calcium. Kinetic and isotherm studies reveal a favorable trend towards quasi-second-order kinetics and Freundlich isotherm models, attributed to cavity heterogeneity and diverse attachment points as evidenced in existing literature. These findings suggest promising applications for these polymers, traditionally employed for organic contaminant removal, as additional filters to mitigate water hardness.

Explainable predictions of a machine learning model to forecast the postoperative length of stay for severe patients: machine learning model development and evaluation.

Predicting the length of stay in advance will not only benefit the hospitals both clinically and financially but enable healthcare providers to better decision-making for improved quality of care. More importantly, understanding the length of stay of severe patients who require general anesthesia is key to enhancing health outcomes. Here, we aim to discover how machine learning can support resource allocation management and decision-making resulting from the length of stay prediction. A retrospective cohort study was conducted from January 2018 to October 2020. A total cohort of 240,000 patients' medical records was collected. The data were collected exclusively for preoperative variables to accurately analyze the predictive factors impacting the postoperative length of stay. The main outcome of this study is an analysis of the length of stay (in days) after surgery until discharge. The prediction was performed with ridge regression, random forest, XGBoost, and multi-layer perceptron neural network models. The XGBoost resulted in the best performance with an average error within 3days. Moreover, we explain each feature's contribution over the XGBoost model and further display distinct predictors affecting the overall prediction outcome at the patient level. The risk factors that most importantly contributed to the stay after surgery were as follows: a direct bilirubin laboratory test, department change, calcium chloride medication, gender, and diagnosis with the removal of other organs. Our results suggest that healthcare providers take into account the risk factors such as the laboratory blood test, distributing patients, and the medication prescribed prior to the surgery. We successfully predicted the length of stay after surgery and provide explainable models with supporting analyses. In summary, we demonstrate the interpretation with the XGBoost model presenting insights on preoperative features and defining higher risk predictors to the length of stay outcome. Our development in explainable models supports the current in-depth knowledge for the future length of stay prediction on electronic medical records that aids the decision-making and facilitation of the operation department.

Synergistic Effects in MoS2/Co3O4/Cu2O Nanocomposites for Superior Solar Cell and Photodegradation Efficiency

Herein, we synthesized a Cu2O and Co3O4 incorporation with MoS2 to produce MoS2/Co3O4/Cu2O nanocomposites by facile sonication assisted hydrothermal methods. The phase structure and elemental composition of MoS2/Co3O4/Cu2O nanocomposites were investigated using X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) techniques. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) morphology studies confirm that MoS2/Co3O4 nanostructure self-assembles in a mixed nanosheet configuration after the introduction of Cu2O. The synthesized samples were used as new types of Pt-free counter electrodes (CE) for DSSCs. Among all, the DSSCs based on the MoS2/Co3O4/Cu2O CE yields a maximum power conversion efficiency of 3.68% (Jsc = 8.2mAcm-2, Voc = 0.71mV and FF = 0.629%) under the standard AM 1.5G illumination, which is 2.5 times higher than that of pure MoS2. To assess the photocatalytic activity, prepared samples were used to suppress methylene blue (MB) and rhodamine B (RhB) dye under UV-visible light irradiation. The MoS2/Co3O4/Cu2O nanocomposites had the highest photocatalytic degradation efficiency of all the samples. It increased degradation efficiency from 43% to 91% for MB dye after 100minutes, and from 47% to 92% for RhB dye after 90minutes. Scavengers test analysis proved that the superoxide radical (•O2-) play a major role in the MoS2/Co3O4/Cu2O photocatalytic system. After four consecutive photocatalytic cycles, the crystal structure and surface morphology of the MoS2/Co3O4/Cu2O nanocomposites used in the 4th cycle were more stable, and this was confirmed by SEM, EDAX and XRD studies. The broader significance of these findings provides a straightforward approach for synthesizing a low-cost and high-efficiency MoS2/Co3O4/Cu2O nanocomposite for CE in DSSC photovoltaic cells and facilitates organic pollutant removal through photocatalytic applications.