Removal Reduction Research Articles

Constructing novel graphitic carbon nitride-based nanocomposites - From the perspective of material dimensions and interfacial characteristics.

Two-dimensional (2D) graphitic carbon nitride (g-C3N4), a fascinating metal-free conjugated polymer, has garnered immense interest in the fields of solar power generation and environmental remediation. The construction of g-C3N4-based nanocomposites with materials of various dimensions can further improve their photocatalytic activities by surface area enlargement, bandgap tuning, heterojunction formation, etc. In this paper, we comprehensively reviewed the design, synthesis, and functionalities of g-C3N4-based nanocomposites based on their applications in hydrogen evolution, CO2 reduction, and pollutants removal. We provided detailed analyses on the integration of 2D g-C3N4 with zero-, one-, two-, and three-dimensional materials with a focus on their interfacial characteristics and functional improvement. This review aims to stimulate fresh ideas on the interfacial engineering of g-C3N4-based nanocomposites to broaden their future applications.

Long-Term Growth of Highway Rights-of-Way Trees

Background: Highway rights-of-ways (ROWs, or verges) contain multiple stressors which can influence tree growth, including compacted soils, soils with little topsoil, poor drainage, air and soil pollutants, construction activities, and de-icing salts in cold climates. Yet highway ROWs often provide ample planting space for growing trees, which can contribute to the mitigation of negative environmental impacts associated with highways. Methods: For this study, we assessed the trunk diameter of 1,058 trees from 11-, 22-, and 31-year-old planting cohorts along a highway in the Chicago metropolitan region (Illinois, USA) to examine factors which could influence long-term growth. We analyzed the impact of location factors within the ROW (e.g., distance and elevation relative to highway, slope, and aspect) on trunk diameter at breast height (DBH), since these factors are relevant to the landscape design process. Using estimates from i-Tree, we compared carbon sequestration, carbon storage, runoff reduction, and air-pollution removal within and among the 3 cohorts. Results: Of the 6 site location characteristics we evaluated, no single characteristic consistently impacted DBH, though some characteristics were significant within a single cohort. DBH measurements of most species were smaller than model predictions based on existing urban tree models. Since all cohorts included large- and small-statured trees, and even within species DBH could be highly variable, the range in per-tree ecosystem services varied substantially within cohorts, especially the 31-year-old cohort. Conclusions: These findings highlight both the potential for and challenges of growing trees alongside highways.

Concurrent tellurite reduction, biogenesis of elemental tellurium nanostructures and biological nutrient removal in aerobic granular sludge sequencing batch reactor

This study investigated the metabolic potential of aerobic granular sludge (AGS) to simultaneously remove tellurium oxyanion (tellurite, TeO32-), COD, ammonium-nitrogen and phosphorus in a sequencing batch reactor (SBR). AGS readily converted soluble and toxic tellurite to biogenic elemental tellurium (Bio-Te0) by following first-order reaction. Bio-Te0 was dark black in colour and largely entrapped in the granules. Although endogenous substrates acted as source of electrons for tellurite reduction, it was sustained by supplying exogenous electron donor. A lab-sale SBR was seeded with AGS and operated at varied initial tellurite concentrations for 185 days to investigate tellurite reduction and biological nutrient removal (BNR). Stable removal efficiencies of > 98% Te was achieved from simulated wastewater containing 0.01–1 mM tellurite. Soluble tellurite was converted to Bio-Te0 and retained in the AGS. SEM-EDS, XRD and Raman spectroscopy confirmed formation of Bio-Te0 and its association with the granules. Enrichment of Bacteroidia, Petrimonas sp. and several other tellurite-reducing bacteria was confirmed by 16S rRNA gene sequencing. Enrichment of ammonium oxidizing bacteria, elimination of nitrite oxidizing bacteria and profiles of reactive-nitrogen compounds suggested occurrence of nitriation-denitriation pathway. Although ammonium removal was inhibited by tellurite, recovery occurred much quickly in the presence of up to 0.1 mM tellurite. Higher P removal under tellurite-reducing condition was linked to hydroxyapatite precipitation as confirmed by EDS and P-fractionation. Efficient BNR under toxic pollutant conditions and excellent metal(loid) immobilization capabilities implicate prospective use of AGS technology in metal-laden waste management and metal(loid) biorecovery applications.

Intradialytic Protein Ingestion and Exercise do Not Compromise Uremic Toxin Removal Throughout Hemodialysis

Dietary protein and physical activity interventions are increasingly implemented during hemodialysis to support muscle maintenance in patients with end-stage renal disease (ESRD). Although muscle maintenance is important, adequate removal of uremic toxins throughout hemodialysis is the primary concern for patients. It remains to be established whether intradialytic protein ingestion and/or exercise modulate uremic toxin removal during hemodialysis. We recruited 10 patients with ESRD (age: 65±16y, BMI: 24.2±4.8kg/m2) on chronic hemodialysis treatment to participate in this randomized cross-over trial. During hemodialysis, patients were assigned to ingest 40g protein or a nonprotein placebo both at rest (protein [PRO] and placebo [PLA], respectively) and following 30min of exercise (PRO+exercise [EX] and PLA+EX, respectively). Blood and spent dialysate samples were collected throughout hemodialysis to assess reduction ratios and removal of urea, creatinine, phosphate, cystatin C, and indoxyl sulfate. The reduction ratios of urea and indoxyl sulfate were higher during PLA (76±6% and 46±9%, respectively) and PLA+EX interventions (77±5% and 45±10%, respectively) when compared to PRO (72±4% and 40±8%, respectively) and PRO+EX interventions (73±4% and 43±7%, respectively; protein effect: P=.001 and P=.023, respectively; exercise effect: P=.25 and P=.52, respectively). Nonetheless, protein ingestion resulted in greater urea removal (P=.046) during hemodialysis. Reduction ratios and removal of creatinine, phosphate, and cystatin C during hemodialysis did not differ following intradialytic protein ingestion or exercise (protein effect: P>.05; exercise effect: P>.05). Urea, creatinine, and phosphate removal were greater throughout the period with intradialytic exercise during PLA+EX and PRO+EX interventions when compared to the same period during PLA and PRO interventions (exercise effect: P=.034, P=.039, and P=.022, respectively). The removal of uremic toxins is not compromised by protein feeding and/or exercise implementation during hemodialysis in patients with ESRD.

Disinfection By-product Precursor Removal by Biochar Derived from Agricultural Waste

Biochar made from agricultural waste products can be used as a low-cost adsorbent targeting dissolved organic matter (DOM). In water treatment plant (WTP), DOM reacts with chlorine-based disinfectant and forms carcinogenic disinfection by-products. The objective of this study was to investigate the applicability of bamboo biochar derived from wood vinegar production waste as an adsorbent for DOM removal and subsequently trihalomethane formation potential (THM-FP) reduction. Raw biochar (BCRaw) and 800°C post-heated biochar (BC800) was tested for its surface characteristics including scanning electron microscopy, Fourier transform infrared spectroscopy and Brunauer, Emmett and Teller analysis. The post-pyrolysis treatment increased the surface area of the biochar from 90.3 to 274 m2 g-1. Raw natural water collected from Tapra WTP, Khon Kaen, Thailand, which uses the Chi River as its water source. The adsorption capacities for dissolve organic carbon at 24-h equilibrium (Qe) of BCRaw and BC800 were 0.148 and 0.551 mg-C g-1 adsorbent, respectively. The adsorption kinetics were described well with a pseudo-second order model, which implied chemisorption and multiple adsorption mechanisms. While THM-FP was relatively unaffected by a treatment with BCRaw, a treatment with BC800 resulted in 12.4% THM-FP reduction and preferential removal of precursor to chloroform over other THMs was observed. Fluorescent excitation-emission matric spectroscopy was employed to characterize DOM before and after treatment with biochar. BC800 achieved greater removal of terrestrial humic-like and fulvic-like DOM, due to the presence of oxygen functional groups, which enhances removal capacity for aromatic compounds. Overall, this study shows the potential use of bamboo biochar derived from waste material as an adsorbent for THM precursor removal.

In situ synthesis of α-Fe2O3/LaFeO3 modified with g-C3N4 and Ti3C2 for construction of multiple Z-scheme/Schottky heterojunctions as an efficient visible-light photocatalyst for Cr (VI) reduction and organic pollutants removal

We report an in situ synthesis of α-Fe2O3/LaFeO3 compounded with g-C3N4 and Ti3C2 MXene to form multiple Z-scheme/Schottky heterojunctions, α-Fe2O3/LaFeO3/g-C3N4 /Ti3C2 (FLCT). In FLCT, α-Fe2O3/LaFeO3 promoted carrier migration, g-C3N4 caused electrons to move directionally toward Ti3C2, inhibiting the carrier complex, and the Ti3C2 substitution of a noble metal provided more adsorption active sites and promoted carrier separation. The synergistic effect of the multiple Z-scheme/Schottky heterojunctions endowed the FLCT composite with an excellent photocatalytic performance. To demonstrate the extensive applicability of the composite materials in the photocatalytic degradation and reduction of wastewater, methylene blue (MB), rhodamine B (Rh B), tetracycline hydrochloride (TC), and hexavalent chromium ions (Cr (VI)) were used as model pollutants; 91.30% of the MB, 84.32% of the Rh B, and 76.11% of the TC were photocatalytic degraded. In addition, 79.60% of the Cr (VI) was photocatalytically reduced by FLCT. These results showed that the composite catalyst exhibited photocatalytic degradation or reduction efficiencies that were 3.41-, 3.86-, 5.44-, and 4.14-fold greater than those of pure LaFeO3 for MB, Rh B, TC, and Cr (VI), respectively. The intrinsic relationship between the composite structure and the photocatalytic performance was investigated to reveal the enhancement mechanism of the composite photocatalytic performance. The charge migration path and pollutant degradation mechanism in the photocatalytic system were elucidated. This work provides a novel concept for designing heterojunction-structured photocatalysts and provides an experimental foundation for photocatalytic technology to treat water pollution.

Coupling electrokinetic with a cork-based permeable reactive barrier to prevent groundwater pollution: A case study on hexavalent chromium-contaminated soil

This work proposes an eco-efficient treatment technology for the remediation of a kaolinite-based clay soil artificially contaminated with hexavalent chromium (50 mg Cr(VI) kg–1 soil), combining electrokinetics (EK) with permeable reactive barriers (PRB) composed of cork granules, the major by-product of cork stoppers production. This 100% natural and sustainable material can act as (i) an electron donor in the Cr(VI) reduction into trivalent chromium [Cr(III)], the less toxic state, and as (ii) a binder for the reduced Cr(III) on its pre-oxidized surface. The EK and Cr(VI) reduction efficiencies were assessed over 15 days as a function of the: (i) supporting electrolyte solution (demineralized water – DW, tap water, citric acid – CA, and sodium chloride – NaCl); and (ii) cork-PRB inclusion and position (near the anodic compartment, using direct current, or in the soil middle section, applying reversal polarity). Results showed that DW was the best supporting electrolyte solution, removing about 33% of total chromium (CrT) from the soil towards the anode, mainly under the Cr(VI) form, even though CA and NaCl presented higher electrical conductivity. Besides, nearly 67% Cr(VI) was reduced into less mobile Cr(III) only by soil-borne electron donor constituents, especially iron (> 6 g kg–1), which impaired the overall Cr migration due to the Cr(III) precipitation/adsorption over/onto the soil. Such reaction was boosted by CA and NaCl electrolytes, which increased H+ ions availability, reaching reduction efficiencies higher than 98%. When the cork-PRB was incorporated into the DW-driven EK process near the anode, the best position owing to the low pH, the Cr(VI) reduction and CrT removal efficiencies improved to about 97% and 42%, respectively. Furthermore, virtually no Cr(VI) migrated to the anolyte/catholyte, and less than 2% Cr(III) was found in the anodic chamber, being c.a. 40% of CrT retained in the cork-PRB as Cr(III) and c.a. 3%/55% of Cr(VI)/Cr(III) into the soil. Notwithstanding, the EK-PRB process can render polluted soil somewhat less dangerous and prevent the spreading of contamination to natural aquifers.

Limited Effects of Precipitation Manipulation on Soil Respiration and Inorganic N Concentrations across Soil Drainage Classes in Northern Minnesota Aspen Forests

It is critical to gain insight into the responses of forest soils to the changing climate. We simulated future climate conditions with growing season throughfall reduction (by 50%) and winter snow removal using a paired-plot design across a soil drainage class gradient at three upland, Populus-dominated forests in northern Minnesota, USA. In situ bulk soil respiration and concentrations of extractable soil N were measured during the summers of 2020–2021. Soil respiration and N concentrations were not affected by throughfall reduction and snow removal, which was largely attributed to the limited treatment effects on soil moisture content and soil temperature. Drainage class was only a significant factor during the spring thaw period in 2021. During this period, the poorly drained plots had lower respiration rates compared to the well-drained plots, which was associated with the drainage class effects on soil temperature. The results of the companion laboratory incubation with varying levels of soil moisture also indicated no effect of the treatment on soil respiration, but effects of drainage class and moisture content on respiration were observed. Our results indicate that the combined effects of reduced summer and winter precipitation on soil respiration and N dynamics may be limited across the range of conditions that occurred in our study.

Styrylpyrone Derivative (SPD) Extracted from Goniothalamus umbrosus Binds to Dengue Virus Serotype-2 Envelope Protein and Inhibits Early Stage of Virus Replication.

A study was conducted to investigate the anti-viral effect of a styrylpyrone derivative (SPD) called goniothalamin and the effects on the dengue virus serotype 2 (DENV-2) replication cycle. The SPD was prepared from the root of Goniothalamus umbrosus after purification with petroleum ether. The isolated SPD was then subjected to gas chromatography–mass spectrometry (GC-MS) and nuclear magnetic resonance (NMR) analyses for structure validation. The cytotoxicity of the SPD was evaluated using a cell viability assay, while the anti-viral activity of the SPD towards DENV-2 was confirmed by conducting a foci reduction assay which involved virus yield reduction, time-of-addition, and time removal assays. Transcriptomic analysis via quantitative real-time polymerase chain reaction (qRT-PCR) using the DENV-2 E gene was conducted to investigate the level of gene transcript. Immunocytochemistry analysis was used to investigate the effects of SPD treatment on protein E expression. Finally, software molecular docking of the SPD and E protein was also performed. The cytotoxicity assay confirmed that the SPD was not toxic to Vero cells, even at the highest concentration tested. In the time-of-addition assay, more than 80% foci reduction was observed when SPDs were administered at 2 h post-infection (hpi), and the reduction percentage then dropped with the delay of the treatment time, suggesting the inhibition of the early replication cycle. However, the time removal assay showed that more than 80% reduction could only be observed after 96 h post-treatment with the SPD. Treatment with the SPD reduced the progeny infectivity when treated for 24 h and was dose-dependent. The result showed that transcript level of the E gene in infected cells treated with the SPD was reduced compared to infected cells without treatment. In immunocytochemistry analysis, the DENV-2 E protein exhibited similar expression trends, shown by the gene transcription level. Molecular docking showed that the SPD can interact with E protein through hydrogen bonds and other interactions. Overall, this study showed that SPDs have the potential to be anti-DENV-2 via a reduction in viral progeny infectivity and a reduction in the expression of the DENV-2 E gene and protein at different phases of viral replication. SPDs should be further researched to be developed into an effective anti-viral treatment, particularly for early-phase dengue viral infection.

A nanoclustered ceria abrasives with low crystallinity and high Ce3+/Ce4+ ratio for scratch reduction and high oxide removal rates in the chemical mechanical planarization

A nanoclustered ceria abrasives with low crystallinity and high Ce3+/Ce4+ ratio for scratch reduction and high oxide removal rates in the chemical mechanical planarization

On the Cross-Validation Bias due to Unsupervised Preprocessing

AbstractCross-validation is the de facto standard for predictive model evaluation and selection. In proper use, it provides an unbiased estimate of a model's predictive performance. However, data sets often undergo various forms of data-dependent preprocessing, such as mean-centring, rescaling, dimensionality reduction and outlier removal. It is often believed that such preprocessing stages, if done in an unsupervised manner (that does not incorporate the class labels or response values) are generally safe to do prior to cross-validation. In this paper, we study three commonly practised preprocessing procedures prior to a regression analysis: (i) variance-based feature selection; (ii) grouping of rare categorical features; and (iii) feature rescaling. We demonstrate that unsupervised preprocessing can, in fact, introduce a substantial bias into cross-validation estimates and potentially hurt model selection. This bias may be either positive or negative and its exact magnitude depends on all the parameters of the problem in an intricate manner. Further research is needed to understand the real-world impact of this bias across different application domains, particularly when dealing with small sample sizes and high-dimensional data.

Encapsulation of bacteria in different stratified extracellular polymeric substances and its implications for performance enhancement and resource recovery

Simultaneous recovery of biopolymers and enhanced bio-reactor performance are promising options for sustainable wastewater treatment, and the bioactivity of sludge after biopolymer extraction is thus critical for the performance of the system. To this end, stratified extracellular polymeric substances (EPS), including slime, loosely bound EPS (LB-EPS), and tightly bound EPS (TB-EPS), were extracted, and the bioactivities of the consequent extraction residues were assessed using aerobic respirogram, kinetic, and flow cytometry (FCM). After the initial weak extraction of slime, the particle size distribution of the sludge significantly decreased, and subsequent extractions of LB-EPS and TB-EPS produced an equivalent size distribution. In contrast, the fractal dimension decreased after each extraction, suggesting that LB-EPS and TB-EPS affected the compactness of flocs rather than the size. The aerobic bacteria distribution estimated using respirogram shows that slime mainly encapsulated heterotrophs while LB-EPS mainly encapsulated nitrifiers. In addition, the ammonia-nitrogen affinity coefficient decreased from 1.79 to 0.28 mg/L when slime was removed, thereby encouraging the activities of autotrophic nitrifiers. Further removal of LB-EPS induced high energy dispersion as the maintenance coefficient m and the metabolic dispersion index μ/m increased from 0.11 to 0.22 and 0.44 to 0.63, respectively. Meanwhile, the yield rate decreased from 0.77 to 0.66. Although pellets that resulted from TB-EPS extraction were not aerobically active as described by respirogram and growth curves, they were still metabolically active as measured by live/dead cell counting and redox sensor green signal. These pellets used more energy for maintenance as indicated by the high maintenance coefficient than those residual after either slime or LB-EPS extraction. In addition, the variation in bacteria community distribution across flocs was related to the variation in temperatures, suggesting that the inner part of a floc might be hotter than the outer side. Therefore, compared to bacteria in the raw sludge, the viable bacteria bounded in LB-EPS and TB-EPS convert more energy to heat rather than growth. These results indicate that energy was dispersed as metabolic heat for the LB-EPS extracted sludge, and removal of LB-EPS favored thermogenesis and sludge reduction. Based on the above findings, a simultaneously EPS-recovery and performance enhancement configuration is thus proposed, which holds great promise for the integration of next-generation wastewater treatment plants.

УЛЬТРАЗВУКОВАЯ ДИАГНОСТИКА ПРИ ФОРМИРОВАНИИ ПИЩЕВОДНОПЛЕВРОКОЖНЫХ ФИСТУЛ

The aim of the study was to study the effectiveness of ultrasound diagnostics in the adhesion of pleural leaves in the formation of esophagopleurocutaneous fistulas. Material and methods. The data on treatment of 19 patients (9 - main group, 10 - control group) who were treated with esophageal perforation in the department of thoracic surgery of Brest Regional Clinical Hospital using diagnostic ultrasound were analyzed. Results. The technique of performing ultrasound examination was determined. The “zone of interest” was visualized in the B-mode with the definition of a hyperechoic line and drainage nearby. The displacement of the visceral pleura together with the lung tissue relative to the parietal pleura indicated the presence of pleural adhesions. Simultaneously detected sign "barcode" in the M-mode was a sign of pleural adhesion, which was maintained constantly during chest excursion. This method was used to determine the prevalence of the area of adhesions, and subsequently the issue of traction or removal of drainage in postoperative patients during the formation of a fistula was resolved. Conclusions. Ultrasound diagnostics in the formation of esophageal pleural fistula in patients with esophageal damage contributes to the detection of early complications, timely removal of drains and reduction of hospitalization time.

Identification of potential plasma protein biomarkers for feline pancreatic carcinoma by liquid chromatography tandem mass spectrometry.

In both humans and cats, pancreatic carcinoma is an aggressive cancer with a grave prognosis. Proteomics techniques have successfully identified several blood-based biomarkers of human pancreatic neoplasia. Thus, this study aims to investigate whether similar biomarkers can be identified in the plasma of cats with FePAC by using liquid chromatography tandem mass spectrometry (LC-MS/MS). To facilitate evaluation of the low abundance plasma proteome, a human-based immunodepletion device (MARS-2) was first validated for use with feline plasma. Marked reduction and/or complete removal of albumin and immunoglobulins was confirmed by analysis of electrophoretograms and mass spectral data. Subsequently, plasma collected from 9 cats with pancreatic carcinoma (FePAC), 10 cats with symptomatic pancreatitis, and 10 healthy control cats was immunodepleted and subjected to LC-MS/MS. Thirty-seven plasma proteins were found to be differentially expressed (p < .05 in one-way ANOVA, FC >2 in fold change analysis). Among these proteins, ETS variant transcription factor 4 (p < .05) was overexpressed, while gelsolin (p < .01), tryptophan 2,3-dioxygenase (p < .05), serpin family F member 1 (p < .01), apolipoprotein A-IV (p < .01) and phosphatidylinositol-glycan-specific phospholipase D (p < .05) were down-regulated in cats with FePAC. Further studies on these potential biomarkers are needed to investigate their diagnostic value.

Potential negative effects of ocean afforestation on offshore ecosystems.

Our scientific understanding of climate change makes clear the necessity for both emission reduction and carbon dioxide removal (CDR). The ocean with its large surface area, great depths and long coastlines is central to developing CDR approaches commensurate with the scale needed to limit warming to below 2 °C. Many proposed marine CDR approaches rely on spatial upscaling along with enhancement and/or acceleration of the rates of naturally occurring processes. One such approach is 'ocean afforestation', which involves offshore transport and concurrent growth of nearshore macroalgae (seaweed), followed by their export into the deep ocean. The purposeful occupation for months of open ocean waters by macroalgae, which do not naturally occur there, will probably affect offshore ecosystems through a range of biological threats, including altered ocean chemistry and changed microbial physiology and ecology. Here, we present model simulations of ocean afforestation and link these to lessons from other examples of offshore dispersal, including rafting plastic debris, and discuss the ramifications for offshore ecosystems. We explore what additional metrics are required to assess the ecological implications of this proposed CDR. In our opinion, these ecological metrics must have equal weight to CDR capacity in the development of initial trials, pilot studies and potential licensing.

Non-Noble Plasmonic Metal-Based Photocatalysts.

Solar-to-chemical energy conversion via heterogeneous photocatalysis is one of the sustainable approaches to tackle the growing environmental and energy challenges. Among various promising photocatalytic materials, plasmonic-driven photocatalysts feature prominent solar-driven surface plasmon resonance (SPR). Non-noble plasmonic metals (NNPMs)-based photocatalysts have been identified as a unique alternative to noble metal-based ones due to their advantages like earth-abundance, cost-effectiveness, and large-scale application capability. This review comprehensively summarizes the most recent advances in the synthesis, characterization, and properties of NNPMs-based photocatalysts. After introducing the fundamental principles of SPR, the attributes and functionalities of NNPMs in governing surface/interfacial photocatalytic processes are presented. Next, the utilization of NNPMs-based photocatalytic materials for the removal of pollutants, water splitting, CO2 reduction, and organic transformations is discussed. The review concludes with current challenges and perspectives in advancing the NNPMs-based photocatalysts, which are timely and important to plasmon-based photocatalysis, a truly interdisciplinary field across materials science, chemistry, and physics.

Solar Drying as an Eco-Friendly Technology for Sewage Sludge Stabilization: Assessment of Micropollutant Behavior, Pathogen Removal, and Agronomic Value

Sewage sludge (SS) is a biosolid that includes nutrients, organic matter, and a mixture of micropollutants and pathogens. Regarding its final disposal, several criteria should be met to avoid the dissemination of the included micropollutants in the environment. Hence, an adequate treatment prior to SS disposal is highly required. Solar drying is being acknowledged as a sustainable process of SS treatment, yet it is still unclear to what extent this technique is efficient. This review aimed to assess the impact of solar drying on the composition of SS from environmental and agronomic standpoints. Herein, we present the state-of-the-art with regard to solar drying efficiency in terms of water content reduction, DM increase, agronomic parameters evolvement, and micropollutant stabilization including pathogens, heavy metals (HMs), and organic micropollutants. The reviewed literature is mostly focused on two drying cycles: summer and winter, thus addressing the extreme conditions met within a year with respect to temperature. Under different climatic conditions, more than 80% of dry matter is reached during summer. In winter, the efficiency decreases to an average of 50% of DM. Negatively correlated to DM content, pathogen concentration in SS significantly decreased, while DM increased. Thus, more efficiency in terms of pathogen abatement is reported in summer than in winter (e.g., 96% against 60% during summer and winter, respectively, under semi-arid climate). The high reliance of solar drying efficiency on weather has been deduced in terms of DM content increase and pathogen removal. Where climatic conditions are not favorable for solar drying, hybrid design and liming are the highly recommended methods to remove pathogens from SS. A few studies on the fate of HMs in SS during solar drying concluded that solar drying does not involve any removal mechanisms. Changes in HM speciation in solar-dried sludge were reported highlighting a decrease in their mobility. As for organic micropollutants (PAHs and antibiotics), only their occurrence in SS is reported in the literature, and their behavior during the solar drying process is still not addressed. This review allowed concluding the following: 1) solar drying is a sustainable, relevant process for SS handing in terms of volume reduction and pathogen removal, particularly in semi-arid regions; 2) solar drying does not lower the SS agronomic value and does not remove HMs, but under semi-arid climate, it changes HM speciation and reduces their mobility. The gap in research regarding organic micropollutant and heavy metal behavior during SS solar drying has been emphasized as a way forward for research within this topic. Hence, more research is required to help stakeholders decide on the feasibility of an agricultural disposal of solar-dried sludge.

Reduction, mineralization, and magnetic removal of chromium from soil by using a natural mineral composite

Reductive immobilization has been a commonly used technique to detoxify Cr(VI) from soil; however, it's challenging to remove the reduced Cr from soil to prevent its re-oxidation. This work explored a natural magnetic composite for the remediation, mineralization, and magnetic removal of Cr(VI) from the soil. It consists of 77% magnetite and 23% pyrrhotite with strong magnetic properties. A series of characterization tests show that composites of magnetite and pyrrhotite are interlaced and closely bonded, and contain no other heavy metals. The Cr(VI) removal rate increases with the decrease in composite particle size. A kinetics study shows that removing Cr(VI) by the composite is likely through both adsorption and reduction. Acidic conditions are more favorable for the immobilization of Cr(VI), at 45.8 mg Cr(VI) removal per g of composite at pH 2. After 100 days of in-situ treatment by the composite, the leaching concentration (TCLP) of Cr(VI)-contaminated soil was 1.95 mg L−1, which was below the EPA limit (5 mg L−1) for hazardous waste. After reduction, the composite was separated from soil by magnetic characteristics, and 58.2% of Cr was found mineralized. The post-treatment Cr-containing composite was analyzed by SEM-EDS, Raman spectra, and XPS. It was found that Cr was mineralized on the surface of the composite in the form of Cr(OH)3, Cr2O3, and FeCr2O4. This indicates that reduction and mineralization of Cr(VI) in the soil can be accomplished through natural magnetic mineral composites and easily separated and removed from the soil, achieving a complete soil cleanup.

A composite Fe–C/layered double oxides (Fe–C/LDO) carrier fabrication and application for enhanced removal of nitrate and phosphate from polluted water with a low carbon/nitrogen ratio

In this study, a multifunctional biofilm carrier (Fe–C/LDO) integrating Fe–C micro-electrolysis with Mg–Al layered double oxides (LDO) was developed and applied in a biofilter aimed to remove nitrogen and phosphorus simultaneously from slightly polluted water with a low carbon/nitrogen (C/N) ratio. Four types of carriers were prepared under different conditions and their performance in nitrate reduction and phosphorus removal were compared. Results showed that the composite Fe–C/LDO carrier prepared with polyethylene glycol as the pore-forming agent demonstrated the highest nitrate reduction rate and phosphorate adsorption capacity (2.09 mg PO43--P·g−1). A biofilter packed with the Fe–C/LDO carrier was investigated under heterotrophic conditions (C/N = 4.13) and complete autotrophic conditions (C/N = 0) during a long-term operation. Good removal of NH4+-N (96–98%), TN (92–96%) and PO43--P (50–58%) were achieved in the biofilter under both heterotrophic and autotrophic conditions. High throughput pyrosequencing analysis revealed that a large population of autotrophic denitrifying bacteria Thiobacillus and Thioalkalispira were enriched in the biofilm. Metagenomic analysis was performed to analyze functional genes related to nitrogen metabolism and carbon cycle, and it confirmed the presence of a whole denitrification and Calvin-Benson-Bassham carbon fixation pathway in biofilm. Finally, the possible mechanisms for nitrogen and phosphorus removal in the biofilter were proposed. The Fe–C/LDO carrier not only enriched abundant autotrophic denitrifying bacteria, but also provided numerous Fe–C galvanic cells for nitrate reduction through micro-electrolysis. In addition, the Mg–Al LDO in combination with iron hydroxides generated during micro-electrolysis may contribute greatly to phosphorus removal. Biofilter packed with the multifunctional Fe–C/LDO carrier could be a promising technology for simultaneous nitrogen and phosphorus removal from slightly polluted water.

A HYBRID TEXTURAL AND GEOMETRICAL FEATURE EXTRACTION TO REVEAL HIDDEN INFORMATION FROM SUSPICIOUS REGIONS ON MAMMOGRAMS

A mammographic feature extraction scheme through textural and geometrical descriptors is examined to implement in a computer-aided diagnosis system for breast cancer diagnosis in this paper. This scheme is verified on a selected subset of suspicious regions (Region of Interest – ROIs) detected on a publicly available mammogram image database constructed by the Mammographic Image Analysis Society. The ROI detection is succeeded using the Chan-Vese active contour modelling after some pre-processing operations which are median filtering, morphological operations, and a region growing method performed for digitization noise reduction, artifact suppression and background removal, and pectoral muscle removal, respectively, applied on mammogram images. Then, a new adaptive convex hull approach is introduced for extracting geometrical descriptors of the ROIs accompanied by the Haralick features extracted from the gray-level co-occurrence matrices for textural description. In addition to geometrical and textural features, a hybrid mammographic feature vector is constructed by concatenating these features. All the three feature vectors are separately utilized to diagnose the ROIs via Random Forest classifier using 5-fold cross-validation. The experimental studies show that the textural features diagnose benignity more specifically and malignancy more accurately; and they are more effective on discriminating healthy ROIs when concatenated with geometrical features. Hence, a feature combination of these three features is proposed for diagnosis. The proposed feature combination is determined to be more effective for more accurate diagnoses of benignity and malignancy.