Removal System Research Articles

Evaluation of a constructed wetlands hybrid system with and without recirculation

The objective of this study was to evaluate the organic matter behavior under the effect of the recirculation of treated domestic sewage in a hybrid system of constructed wetlands. This study was carried out at the sewage treatment plant in the Instituto Federal Goiano campus, in Rio Verde city, Goias, Brazil. The treatment system consists of a septic tank followed by a hybrid system of constructed wetlands (CW). Sewage monitoring was performed at 3 points: PTS (previously treated sewage), TS1 (VS-CW output) and TS2 (HS-CW output). Water quality analysis were carried out weekly, between May and December 2021, in two types of operation: no recirculation (10 weeks) and 100% recirculation (17 weeks). In this research, three kinetics models were evaluated (1st Order, Monod and Monod Multi) combined with two types of idealized dynamic flow: PFR and CSTR. Results show that the water behavior of the recirculation system increasing by 335% and 59.25% in inlet and outlet flows, respectively, from the VS-CW. The overall efficiency in BOD removing was 89.26% in linear system and 83.95% in the recirculating system. In the case of COD, an overall removal system was 69.7% in the linear and 25.7% in the recirculating system. The Monod kinetic model was the most representative to describe the BOD removal in the linear system (R² = 0.80) and in the recirculation (R² = 0.61). None of the models were included in the description of the linear COD removal processes in the system. In the recirculating system, the Monod kinetic model (R² = 0.81) was the most representative in terms of concentration. Sewage recirculation brought new treatment dynamics and was efficient in BOD reducing (concentration). It is noteworthy that the BOD and COD removal efficiency was lower than in the recirculation by sewage dilution in the suction well.

Removal of melanoidin from baker yeast plant wastewater: A comparative study on chemical and biological processes

Dark brown color and large quantities of chemical oxygen demand (COD) are challenging for the successful treatment of molasses-based baker's yeast (BY) wastewater. In this study, the sequential biological and chemical coagulation processes were compared in terms of their ability to remove color and COD from industrial molasses-based BY wastewater. In the sequential chemical-biological processes, using the desired dosages of ferric chloride (FeCl3, 4 g/L) and calcium oxide (CaO, 2 % (w/v)) as coagulating agents, the color and COD removal were 90.6 % and 57 %, respectively. The COD removal of the samples from chemical pre-treated wastewater in an aerated biological reactor (reactor A) was improved to 78 %. In sequential biological-chemical processes with extended aeration (bioreactor A), the COD and color removal were 89.1 % and 93.7 %, respectively. The chemical post-treating of the effluent of the combined anaerobic-aerobic system (reactor C) led to COD and color removal of 80.8 % and 94.65 %, respectively. According to experimental findings, the chemical post-treatment was more efficient than the chemical pre-treatment process. This study offers new insights into the utilization of combined systems for the efficient removal of color and COD from industrial wastewater.

Metabolomic reveals the responses of sludge properties and microbial communities to high nitrite stress in denitrifying phosphorus removal systems

Nitrite, as an electron acceptor, plays a good role in denitrifying phosphorus removal (DPR); however, high nitrite concentration has adverse affects on sludge performance. We investigated the precise mechanisms of responses of sludge to high nitrite stress, including surface characteristics, intracellular and extracellular components, microbial and metabolic responses. When the nitrite stress reached 90 mg/L, the sludge settling performance was improved, but the activated sludge was aging. FTIR and XPS analysis revealed a significant increase in the hydrophobicity of the sludge, resulting in improve settling performance. However, the intracellular carbon sources synthesis was inhibited. In addition, the components in the tightly bound extracellular polymeric substances (TB-EPS) of sludge were significantly reduced and indicated the disturb of metabolism. Notably, Exiguobacterium emerged as a new genus when face high nitrite stress that could maintaining survival in hostile environments. Moreover, metabolomic analysis demonstrated strong biological response to nitrite stress further supported above results that include the inhibited of carbohydrate and amino acid metabolism. More importantly, some lipids (PS, PA, LysoPA, LysoPC and LysoPE) were significantly upregulated that related enhanced membrane lipid remodeling. The comprehensive analyses provide novel insights into the high nitrite stress responses mechanisms in activated sludge systems.

Effectiveness of Manual Hysteroscopic Tissue Removal Device for Intrauterine Polyps in Infertile Women in Both Operating and Office Settings.

Background: Mechanical hysteroscopic tissue removal (mHTR) systems are widely used for removing intrauterine pathology. Given the startup and procedural costs for electrically powered mechanical units, disposable manual mHTR systems have been developed. Methods: With little published, we describe its effectiveness for hysteroscopic intrauterine polypectomy. Results: One-hundred fifty-seven infertile women underwent hysteroscopic polypectomy with the manual mHTR device. Complete removal was accomplished in all but three cases, with blood loss being <10 mL and all specimens deemed sufficient for histopathologic diagnosis. Conclusions: These results suggest that the disposable manual mHTR system is effective in removing endometrial polyps. Head-to-head comparisons with other alternative technologies are needed.

Robodeport or surveillance fantasy?: how automated is automatic visa cancellation in Australia?

Australia has been widely condemned for its harsh and comprehensive external border controls that seek to control the inward mobility of would-be asylum seekers through visa denial, interdiction and offshore detention. Less widely discussed is the fact that internal controls have been repeatedly ramped up over the past two decades. This includes the administrative removal of lawfully-present non-citizens following visa cancellation on character grounds under s501 of the Migration Act 1958 (Cth). Automatic visa cancellation was introduced in 2014 for non-citizens sentenced to a prison term of 12 months or more, or for certain offences, bypassing individualised decision-making and raising the spectre of a visa cancellation pipeline feeding a highly automated deportation machinery. In an age of increasingly automated forms of governance, a key question that arises is the role that has been played by automated systems in achieving what has been a seismic shift in practice, and the normative implications of any developments towards automation within the visa cancellation and removal systems. This paper outlines the shift towards automation in other systems of governance in Australia-most notably the notorious Robodebt scheme-before examining automation in Australia's visa cancellation system. Documentary analysis of recent parliamentary inquiries, independent reports and government policy is used to piece together the development of inter-agency data exchange practices and automation over three specific periods-historical practice pre-2014, post-2014 to the present, and proposed future developments. We conclude that Australia's s501 visa cancellation system is neither automated nor automatic. Rather, the 2014 law reform gave rise to a 'surveillance fantasy' with immense consequences for non-citizens, particularly those who face long days in immigration detention at the conclusion of their prison sentence. We show that while concerns about increasing automation are well-founded, systems based on less sophisticated forms of information handling and reliant on human decision-making nevertheless continue to raise age-old questions concerning efficiency, accuracy and fairness.

Electrochemical-coupled sulfur-driven autotrophic denitrification for nitrogen removal from raw landfill leachate: Evaluation of performance and mechanisms

The cost-effective and environment-friendly sulfur-driven autotrophic denitrification (SdAD) process has drawn significant attention for advanced nitrogen removal from low carbon-to-nitrogen (C/N) ratio wastewater in recent years. However, achieving efficient nitrogen removal and maintaining system stability of SdAD process in treating low C/N landfill leachate treatment have been a major challenge. In this study, a novel electrochemical-coupled sulfur-driven autotrophic denitrification (ESdAD) system was developed and compared with SdAD system through a long-term continuous study. Superior nitrogen removal performance (removal efficiency of 89.1 ± 2.5 %) was achieved in ESdAD system compared to SdAD process when treating raw landfill leachate (influent total nitrogen (TN) concentration of 241.7 ± 36.3 mg-N/L), and the effluent TN concentration of ESdAD bioreactor was as low as 24.8 ± 5.1 mg-N/L, which meets the discharge standard of China (< 40 mg N/L). Moreover, less sulfate production rate (1.3 ± 0.2 mg SO42−−S/mgNOx−−N vs 1.7 ± 0.2 mg SO42−−S/mgNOx−−N) and excellent pH modulation (pH of 6.9 ± 0.2 vs 5.8 ± 0.4) were also achieved in the ESdAD system compared to SdAD system. The improvement of ESdAD system performance was contributed to coexistence and interaction of heterotrophic bacteria (e.g., Rhodanobacter, Thermomonas, etc.), sulfur autotrophic bacteria (e.g., Thiobacillus, Sulfurimonas, Ignavibacterium etc.) and hydrogen autotrophic bacteria (e.g., Thauera, Comamonas, etc.) under current stimulation. In addition, microbial nitrogen metabolic activity, including functional enzyme (e.g., Nar and Nir) activities and electron transfer capacity of extracellular polymeric substances (EPS) and cytochrome c (Cyt-C), were also enhanced during current stimulation, which facilitated the nitrogen removal and maintained system stability. These findings suggested that ESdAD is an effective and eco-friendly process for advanced nitrogen removal for low C/N wastewater.

Efficient removal of Basic Violet 16 by a multistage oxygen enhanced liquid glow discharge plasma system: Mechanism and roles of reactive species quantified by machine learning

A multistage oxygen enhanced Liquid Glow Discharge Plasma reactor (LGDP/multistage oxygen, LGDP/M-O2) was designed to improve the removal efficiency of organic dyes in wastewater. As a result of the multistage oxygen system, the degradation rate constant of Basic Violet 16 (BV16) was enhanced by approximately 18 times, the decolorization rate of BV16 was 97.39 % in 4 min, and the removal rate of TOC was 33.32 % in 10 min. Detailed study of how the system works to help break down pollutants. The reactive species series of experiments showed that multistage oxygen injection strongly promoted reactive species production and utilization. Meanwhile, a machine learning model to quantify the contribution of reactants was proposed. Machine learning indicated the dominating contribution of reactive oxygen species (63.89 %) and reactive chlorine species (21.92 %) in the degradation of BV16. In addition, the transformation intermediates during the degradation of BV16 were monitored. Accordingly, three possible degradation pathways of BV16 in the LGDP/M-O2 system were proposed, i.e., benzene ring substitution of hydroxyl groups, hydroxyl addition of C=C double bond, and halogenation of benzene rings. This study demonstrates the importance of the LGDP/M-O2 system for organic dye removal from wastewater.

Accuracy Evaluation of Monte Carlo Simulation Results Using ENDF/B-VIII.0 and JENDL-5 Libraries for 10 MWth Micro Heat Pipe-Cooled Reactor

The micro heat pipe-cooled reactor is an innovative type of reactor that utilizes heat pipes to cool its core. It consists of a reactor core, an energy conversion system, shielding, and a heat removal system. This reactor shows great potential as a viable option for supplying electricity in remote areas. By incorporating a monolithic core with heat pipes and an efficient heat conversion system, this reactor design eliminates the need for a main pipeline, circulating pump, and auxiliary equipment, resulting in a cost-effective, compact, and transportable system. The monolithic reactor design has undergone significant advancements in neutronics and thermal hydraulics. This article focuses on evaluating the impact of the latest released nuclear data libraries, ENDF/B-VIII.0 and JENDL-5, on calculated neutronics and kinetics parameters. The total keff uncertainty was propagated and found to be significant for both recently evaluated nuclear data libraries (678.52 pcm for ENDF/B-VIII.0 and 525.91 pcm for JENDL-5, respectively). The total uncertainty originated from nuclear data was evaluated for total ν, reaction cross sections, and angular distributions in the case of JENDL-5, and for ENDF/B-VIII.0, uncertainty from angular distributions was not included because of the unavailability of its multigroup structure covariance matrices. The results reveal that the largest contributor for ENDF/B-VIII.0 is 235U total (409.18 pcm), while that for JENDL-5 is 56Fe capture cross section (361.93 pcm). For the kinetic parameter’s uncertainty, the impact on the total βeff, leff, and λeff simulation results was found to be not significant (about 1%).

Progress in Fast Modular Reactor Conceptual Design

The Fast Modular Reactor (FMR) is a 100-MW(thermal) gas-cooled fast reactor being developed by General Atomics Electromagnetic System with the goal of developing a FMR for flexible and dispatchable power to the U.S. electricity market in the mid-2030s. The conceptual design aims to develop and verify simplified design features. These include an inert helium gas coolant, pellet-loaded fuel rods, installations with air cooling as ultimate heat sink, and small and passive heat removal systems. The goal is to ensure the development of a safe, maintainable, cost-effective, and distributed nuclear energy-generating station. The baseline technologies selected to achieve this goal are a helium coolant that is an inert gas with no chemical reaction with structural components, not activated, single phase, enabling high-temperature operation and a high thermal efficiency Brayton cycle; conventional uranium dioxide (UO2) fuel, which is the most widely used and well-known fuel material, capable of high burnup (100 MWd/kg) and a long fuel life; and silicon carbide composite (SiGA®) cladding and internal structures that are chemically inert in the helium environment, exceptionally radiation tolerant, and being derisked by accident tolerant fuel technology development. The reactor was specifically designed with passive safety features, including high-temperature in-core materials and a reactor vessel cooling system consisting of cooling panels of naturally circulating water. The passive safety of the core was confirmed for the depressurized loss-of–forced cooling accident, which showed the peak cladding temperature at ~1600°C during the transient, which is below the current design limit of 1800°C. The conceptual design of the FMR has been conducted for the reactor system, vessel system, generator and turbomachine, instrumentation and control, residual heat removal system, plant service system, and containment, as well as pre-application licensing documents.

Comparative Evaluation of the Efficacy of ProTaper & Mtwo Rotary Retreatment System and Conventional Hand H-files for Removal of Gutta-percha from Root Canal - A Stereomicroscopic Study.

Root canal retreatment aims to eliminate or substantially reduce the microbial load from the root canal and removal of previous root filling materials is the primary goal of nonsurgical retreatment. To comparatively evaluate the effectiveness of ProTaper retreatment files, Mtwo retreatment files, and Hedstrom files along with Gates Glidden (GG) Drill by using a stereomicroscope for the detection of remaining gutta-percha after root canal retreatment using a stereomicroscope. Forty-five test samples were divided into three experimental groups (15 samples each), such as Group A-ProTaper retreatment files; Group B-Mtwo retreatment files; Group C-Hedstrom files along with Gates Glidden Drill. After routine endodontic treatment in the test samples, gutta-percha was removed from the test samples as per the division of different retreatment file systems. Further, test samples were divided longitudinally and were evaluated under the stereomicroscope. Stereomicroscopic images were captured and analysed under Image Analyser Software-Image J. One-way ANOVA test was used for comparison of gutta-percha removal between the groups and Tukey's post hoc test was used for pairwise comparisons. The least remaining filling material was seen in specimens retreated with the ProTaper universal system. The highest remaining filling material was seen in specimens retreated with Hedstrom file with Gates Glidden Drill. All experimental test techniques left gutta-percha remnants within the root canal. ProTaper universal rotary retreatment system proved to be an efficient method of removing gutta-percha and left relatively less volume in comparison with other test systems.

A Retrospective Analysis of AngioVac Outcomes at a Tertiary Care Center

BackgroundThe AngioVac system is a vacuum aspiration device approved for removal of right-sided cardiac thrombi. It has also been used for management of right-sided endocarditis in selected cases. Retrospective case series have reported high success rate and acceptable 30-day mortality, but there is limited data regarding outcomes beyond the immediate postoperative period. The purpose of this study is to describe our institution's experience with the AngioVac system for thrombus, vegetation, and tumor removal with a significant improvement over previously reported 1-year survival rates. MethodsA retrospective review of AngioVac cases performed at our tertiary care center from 2016-2022 was done. From 2016-2022, 23 patients were identified, and their outcomes are described. ResultsOur review demonstrates 81.8% procedural success, 100% procedure survival, 90.9% survival to discharge, and 81.8% 30-day survival rates. One-year survival rate was 72.7%. Complications including an 18.2% rate of new vasopressor use, 54.5% rate of transfusion requirement, and 4.5% rate of acute renal failure requiring hemodialysis were identified. Intraprocedural embolization occurred in 1 case requiring venoarterial extracorporeal membrane oxygenation support and thrombectomy. One case was converted to open surgical intervention. ConclusionsOur review further supports the safety and efficacy of minimally invasive vacuum-assisted aspiration systems beyond the immediate postoperative period in intracardiac thrombus, tumor, and right-sided infective endocarditis. Our institution's experience emphasizes a team-based approach including interventional cardiology and cardiothoracic surgery with a standardized imaging approach with transesophageal echocardiogram. Future guidelines are needed to include an algorithmic approach to intracardiac masses.

Simultaneous removal of caesium and strontium using different removal mechanisms of probiotic bacteria

When radioactive materials are released into the environment due to nuclear power plant accidents, they may enter into the body, and exposing it to internal radiation for long periods of time. Although several agents have been developed that help excrete radioactive elements from the digestive tract, only one type of radioactive element can be removed using a single agent. Therefore, we considered the simultaneous removal of caesium (Cs) and strontium (Sr) by utilising the multiple metal removal mechanisms of probiotic bacteria. In this study, the Cs and Sr removal capacities of lactobacilli and bifidobacteria were investigated. Observation using an electron probe micro analyser suggested that Cs was accumulated within the bacterial cells. Since Sr was removed non metabolically, it is likely that it was removed by a mechanism different from that of Cs. The amount of Cs and Sr that the cells could simultaneously retain decreased when compared to that for each element alone, but some strains showed only a slight reduction in removal. For example, Bifidobacterium adolescentis JCM1275 could simultaneously retain 55.7 mg-Cs/g-dry cell and 8.1 mg-Sr/g-dry cell. These results demonstrated the potentials of utilizing complex biological system in simultaneous removal of multiple metal species.

Microalgae as a single-pot system for nutrient removal and wastewater treatment: comparison of effluents and species performance

Microalgae as a single-pot system for nutrient removal and wastewater treatment: comparison of effluents and species performance

Advancing wastewater treatment technologies: The role of chemical engineering simulations in environmental sustainability

Wastewater treatment stands as a critical component in mitigating environmental pollution and safeguarding public health. This review delves into the pivotal role of chemical engineering simulations in advancing wastewater treatment technologies towards enhanced environmental sustainability. The modernization of wastewater treatment processes necessitates a comprehensive understanding of the complex physical, chemical, and biological interactions involved. Chemical engineering simulations offer a powerful toolset for modeling and optimizing these processes with a focus on efficiency, effectiveness, and sustainability. Firstly, simulations enable the prediction and analysis of pollutant removal mechanisms within treatment systems. By simulating various operating conditions and configurations, engineers can optimize treatment processes to achieve higher removal efficiencies while minimizing resource consumption and waste generation. Secondly, simulations aid in the design and development of innovative treatment technologies, such as membrane filtration, advanced oxidation processes, and biological nutrient removal systems. Through computational modeling, engineers can assess the performance and feasibility of these technologies under different scenarios, facilitating informed decision-making and accelerating their implementation. Furthermore, chemical engineering simulations play a crucial role in addressing emerging challenges in wastewater treatment, including the removal of emerging contaminants such as pharmaceuticals, microplastics, and endocrine-disrupting chemicals. By simulating the behavior of these contaminants within treatment systems, engineers can devise targeted strategies for their removal, thus mitigating their adverse environmental and public health impacts. Chemical engineering simulations serve as indispensable tools for advancing wastewater treatment technologies towards greater environmental sustainability. By facilitating the optimization, design, and innovation of treatment processes, simulations contribute to the development of more efficient, cost-effective, and environmentally friendly solutions for managing wastewater and protecting our ecosystems. Embracing these simulation-driven approaches is essential for achieving the ambitious goals of sustainable development and ensuring a cleaner, healthier future for generations to come.

Study on a chelating removal system for dissolving barite mud cake

Study on a chelating removal system for dissolving barite mud cake

A hybrid system for Nickel ions removal from synthesized wastewater using adsorption assisted with electrocoagulation.

The presence of heavy metal ions in water environments has raised significant concerns, necessitating practical solutions for their complete removal. In this study, a combination of adsorption and electrocoagulation (ADS + EC) techniques was introduced as an efficient approach for removing high concentrations of nickel ions (Ni2+) from aqueous solutions, employing low-cost sunflower seed shell biochar (SSSB). The combined techniques demonstrated superior removal efficiency compared to individual methods. The synthesized SSSB was characterized using SEM, FT-IR, XRD, N2-adsorption-desorption isotherms, XPS, and TEM. Batch processes were optimized by investigating pH, adsorbent dosage, initial nickel concentration, electrode effects, and current density. An aluminum (Al) electrode electrocoagulated particles and removed residual Ni2+ after adsorption. Kinetic and isotherm models examined Ni2+ adsorption and electrocoagulation coupling with SSSB-based adsorbent. The results indicated that the kinetic data fit well with a pseudo-second-order model, while the experimental equilibrium adsorption data conformed to a Langmuir isotherm under optimized conditions. The maximum adsorption capacity of the activated sunflower seed shell was determined to be 44.247mg.g-1. The highest nickel ion removal efficiency of 99.98% was observed at initial pH values of 6.0 for ADS and 4.0 for ADS/EC; initial Ni2+ concentrations of 30.0mg/L and 1.5g/L of SSSB; initial current densities of 0.59mA/cm2 and 1.32 kWh/m3 were also found to be optimal. The mechanisms involved in the removal of Ni2+ from wastewater were also examined in this research. These findings suggest that the adsorption-assisted electrocoagulation technique has a remarkable capacity for the cost-effective removal of heavy metals from various wastewater sources.

Development of a Low Cost System for The Removal of Heavy Metals from Polluted Water

Water pollution by heavy metals has become one of the most harmful environmental issues. This study developed a low cost heavy metal (lead and chromium) removal system from polluted water using locally available adsorbents, such as sawdust, pawpaw (Carica papaya) seeds and sand. Heavy metals constitute a serious threat to human health and the entire biological system due to their toxic, mutagenic, and carcinogenic nature even at trace concentrations. The objective of this study was to design and construct a low cost heavy metals removal system, test its performance and do a cost analysis of the system. In this process, a filter column made of a plastic container of height 54 cm and diameter 20.4 cm was constructed. Characteristic properties of the adsorbents were obtained from secondary sources and were found to possess functional groups (hydroxyl, carbonyl, aldehyde and amine) capable of binding to metal ions. Optimization was done with a sawdust and pawpaw seeds/sand height ratios of 10:10, 10:15, 15:10, 20:10 and 10:20 cm respectively in the filter column. Results showed that the best removal efficiencies were 99.88% for lead and 85.57% for chromium with a sawdust to pawpaw seeds/sand mixture ratio of 10:20 cm. Statistical analysis showed a significant difference (p &lt; 0.05) in the final concentrations of lead and chromium using the various adsorbent proportions. Cost per liter of treated water was deduced to be 15.5 FCFA. This cost can be afforded by many households with low incomes and thus, this low cost heavy metals removal technology is highly recommended.

Synthesis of Cu-doped TiO2 modified BiVO4 for photocatalytic oxidative desulfurization (PODS) of a model fuel

In the present study, a photocatalytic oxidation desulfurization method is used to eliminate dibenzothiophene as one of the aromatic sulfur derivatives in fuel, using a Cu-TiO2/BiVO4 composite. The structure of the synthesized compounds was characterized by FT-IR and Raman spectroscopy, XRD, DRS, UV–Vis, BET, TEM, FE-SEM, elemental mapping, EDS, XPS, and ICP-MS methods. To find the best results in this photocatalytic system, different parameters such as type of solvent, the amount of photocatalyst, reaction time, amount of oxidizing agent, reaction temperature, and the ratio of extracting solvent to n-heptane as the model fuel was investigated and optimized. Desulfurization tests were carried out including extraction-absorption test (without H2O2), in the absence of photocatalyst, and test in dark conditions followed by oxidation extraction test. The efficiency of this photocatalytic system for dibenzothiophene removal reached 93% under optimal reaction conditions for the model fuel. The photocatalyst was recycled three times and exhibited good efficiency in dibenzothiophene removal.

Prediction and optimization of the efficiency and energy consumption of an ammonia vacuum thermal stripping process using experiments and machine learning models

In this study, we adjusted the effluent temperature and pH to optimize the ammonia stripping efficiency and energy consumption using quadratic equation (QE) and machine learning models, including multi-layer perceptron (MLP), random forest (RF), and extreme gradient boosting (XGBoost) models. The experimental results for the one-factor-at-a-time method revealed that the stripping efficiency increased with both temperature and pH. However, the energy consumption required to reduce the ammonia concentration by an order of magnitude did not show the same with the experimental result of stripping efficiency; rather, it was lowest when the temperature was 40 °C and the pH was 11.5. The response surface for the ammonia stripping efficiency predicted using the QE and machine learning models exhibited a similar trend to the experimental results. Analysis of variance for the QE model revealed that pH, temperature, and reaction time were important factors determining the stripping efficiency. The feature importance analysis revealed that temperature and pH made similar contributions. The RF and XGBoost models also produced relatively reliable results (R2 > 0.98). The validation of RF and XGBoost models using the additional data from optimal conditions (treatment time = 78.456 min at pH = 11.079 and temperature = 37.632 °C for RF and treatment time = 62.499 min at pH = 11.079 and temperature = 42.895 °C for XGBoost) proved the reliability of both models (observed treatment times were 80.316 and 65.210 min, respectively). This study offers implications for designing effective and energy-efficient systems for ammonia removal from anaerobic digestion effluent.

Unraveling the effect mechanism of sulfamethoxazole on nitrogen biotransformation in a PHBV supported denitrifying granular sludge

Sulfamethoxazole (SMX) is prevalent as one of the most frequently detected antibiotics in rivers worldwide, and is listed as one of the priority antibiotics in China based on the persistence, bioaccumulation, toxicity and resistance. Recently, the effect of SMX on aerobic granular sludge has attracted increasing interest. However, how SMX influences the biodegradable polymer supported denitrifying granular sludge is still obscure. Herein, two groups with or without exposure to 1 mg/L SMX with initial nitrate concentrations of 15, 30, and 50 mg/L were constructed. Results showed that there was a negligible difference on nitrate removal efficiencies between two groups under stable period (all exceeded 95 %) in batch bioreactors with an HRT of 24 h, supported by an insignificance difference (p > 0.05). However, the decline in the first-order decay kinetic constants of nitrate removal rate, NAR and NIR activities verified a slight inhibition of SMX on denitrification. Meanwhile, SMX also had an impact on the chemical and microbial properties on granular sludge. SMX boosted the EPS secretion with more humic acid, a delicate rise in PN/PS ratios and a decrease in zeta potential of EPS all favored the microbes' survival under SMX stress. SMX shifted the microbial compositions, namely, the microbes directly involving in PHBV degradation (Caldimonas, denitrificans Comamonas/Diaphorobacter) were enriched instead of some denitrifying microorganism that could not directly utilize PHBV (Denitratisoma, Azospira). Additionally, even though sul1 and sul2 were enriched, which was not readily accessible to receiving waters due to a good settling properties of granular sludge. This work contributes to a deeper understanding of the impact of SMX on this system, and is of great significance for the operation of granular sludge system for nitrate removal under antibiotic's stress.