Oxalate modification enabled advanced phosphate removal of nZVI: In Situ formed surface ternary complex and altered multi-stage adsorption process.

Nano zero-valent iron (nZVI) is a promising phosphate adsorbent for advanced phosphate removal. However, the rapid passivation of nZVI and the low activity of adsorption sites seriously limit its phosphate removal performance, accounting for its inapplicability to meet the emission criteria of 0.1 mg P/L phosphate. In this study, we report that the oxalate modification can inhibit the passivation of nZVI and alter the multi-stage phosphate adsorption mechanism by changing the adsorption sites. As expected, the stronger anti-passivation ability of oxalate modified nZVI (OX-nZVI) strongly favored its phosphate adsorption. Interestingly, the oxalate modification endowed the surface Fe(III) sites with the lowest chemisorption energy and the fastest phosphate adsorption ability than the other adsorption sites, by in situ forming a Fe(III)-phosphate-oxalate ternary complex, therefore enabling an advanced phosphate removal process. At an initial phosphate concentration of 1.00 mg P/L, pH of 6.0 and a dosage of 0.3 g/L of adsorbents, OX-nZVI exhibited faster phosphate removal rate (0.11 g/mg/min) and lower residual phosphate level (0.02 mg P/L) than nZVI (0.055 g/mg/min and 0.19 mg P/L). This study sheds light on the importance of site manipulation in the development of high-performance adsorbents, and offers a facile surface modification strategy to prepare superior iron-based materials for advanced phosphate removal.

Highly efficient removal of aqueous phosphate via iron-manganese fabricated biochar: Performance and mechanism.

Biochar (BC) has emerged as a potential solution to phosphate removal from wastewater primarily resulting from global overuse of fertilizers. Further modification by embedment of iron (Fe)-manganese (Mn) oxides on BC can enhance phosphate removal; however, the modification method serves as a vital factor underlying distinctive removal performances and mechanisms, which have yet been systematically examined. Herein, two Fe-Mn modified BC, Fe/MnBC (comprised of Fe3O4 and MnO2) and Fe-MnBC (comprised of MnFe2O4), were comprehensively investigated for gaining insights into the unsolved perspectives. The results indicated that Fe-MnBC exhibited a markedly greater maximum phosphate adsorption capacity of 135.88 mg g-1 than that of Fe/MnBC with 17.93 mg g-1. The comparative results based on microstructure and spectroscopic analyses suggested that different Fe and Mn oxides were successfully loaded, which played a distinctive role in phosphate removal. Further characterizations unveiled that the key mechanisms for phosphate removal by Fe/MnBC are inner-sphere complexation and precipitation, while electrostatic interaction and outer-sphere complexation are the dominant mechanisms underlying the notable performance of Fe-MnBC. The delicately designed Fe-MnBC with special structure and property also enabled a superior regeneration capacity, which presented a promisingly high phosphate removal efficacy of over 81.34% after five cycles. These results enhance comprehension regarding the impact of biochar modification techniques on phosphate removal, offering positive indications for the remediation of excessive phosphate and other pollutant-containing water through feasible design and green chemicals.

Unraveling the impact of Spartina alterniflora invasion on greenhouse gas production and emissions in coastal saltmarshes: New insights from dissolved organic matter characteristics and surface-porewater interactions.

Saltmarshes along the Chinese coast are threatened by the invasion of Spartina alterniflora (S. alterniflora). This study was carried out in the Andong Shoal, Hangzhou Bay, China, with the aim of comprehending the intricate impacts of S. alterniflora invasion on greenhouse gases (GHG) production and emissions. To address this issue, we thoroughly examined the chemistry of dissolved organic matter (DOM) and the rate of surface water-porewater interaction. Porewater and surface water samples were collected from farm land, S. alterniflora invaded areas, and Scirpus mariqueter (S. mariqueter) dominated areas. The findings indicated that the invasion of S. alterniflora impeded the interaction between surface water and porewater, resulting in reduced porewater exchange rates within its affected region (0.015-0.440 cm d-1), in contrast to areas dominated by S. mariqueter (9.635-18.232 cm d-1). The invasion also increased dissolved organic carbon concentration in porewater and created a stable and closed soil environment that resulted in DOM with smaller molecule sizes and higher humification levels. The presence of high tryptophan-like fluorescent DOM caused an increase in the production of methane and carbon dioxide in S. alterniflora invaded area. However, both limited surface-porewater exchange and significant differences in GHG concentrations between porewater and surface water suggested that the aerenchyma tissues of S. alterniflora may play an important role in transporting GHG from soil to the atmosphere.

Cadmium Isotope Fractionation during Adsorption onto Edge Sites and Vacancies in Phyllomanganate.

Cadmium (Cd) geochemical behavior is strongly influenced by its adsorption onto natural phyllomanganates, which contain both layer edge sites and vacancies; however, Cd isotope fractionation mechanisms at these sites have not yet been addressed. In the present work, Cd isotope fractionation during adsorption onto hexagonal (containing both types of sites) and triclinic birnessite (almost only edge sites) was investigated using a combination of batch adsorption experiments, extended X-ray absorption fine structure (EXAFS) spectroscopy, surface complexation modeling, and density functional theory (DFT) calculations. Light Cd isotopes are preferentially enriched on solid surfaces, and the isotope fractionation induced by Cd2+ adsorption on edge sites (Δ114/110Cdedge-solution = -1.54 ± 0.11‰) is smaller than that on vacancies (Δ114/110Cdvacancy-solution = -0.71 ± 0.21‰), independent of surface coverage or pH. Both Cd K-edge EXAFS and DFT results indicate the formation of double corner-sharing complexes on layer edge sites and mainly triple cornering-sharing complexes on vacancies. The distortion of both complexes results in the negative isotope fractionation onto the solids, and the slightly longer first Cd-O distances and a smaller number of nearest Mn atoms around Cd at edge sites probably account for the larger fractionation magnitude compared to that of vacancies. These results provide deep insights into Cd isotope fractionation mechanisms during interactions with phyllomanganates.

MgO-based supersulfated cement with different industrial by-product gypsum: Experiments and molecular dynamics simulation.

Super sulfate cement (SSC) emerges as a sustainable alternative to ordinary Portland cement, boasting minimal carbon emissions and exceptional performance. As the quest for eco-friendly alternatives intensifies, there's a growing focus on exploring alkaline and sulfate activators conducive to SSC's environmental goals. This study delves into the viability of utilizing MgO as an alkaline activator in producing MgO-based supersulfated cement, while also investigating the impact of various industrial by-product gypsums on its performance. Findings reveal that employing MgO as an alkaline activator yields favorable hydration properties and mechanical strength in SSC. The optimized formulation comprises 15 % industrial by-product gypsum, 83 % granulated blast furnace slag (GGBFS), and 2 % MgO. Incorporating building gypsum and flue gas desulfurization (FGD) gypsum demonstrates superior unconfined compressive strength (UCS) growth compared to citric gypsum and phosphogypsum. Notably, gel-pores below 20 nm dominate the matrix, with variations in their distribution linked to the gypsum type used. The pH level and crystal structure of the industrial by-product gypsum emerge as pivotal factors dictating the hydration process. The interaction energy between hydrated building gypsum crystal planes and water molecules proves lower, contributing to the root cause of its high sulfate activating capability. Compared to traditional SSC, MgO-based supersulfated cement requires less alkaline activator content and accommodates more industrial by-product gypsums, thus reducing costs, CO2 emissions, and promoting the efficient utilization of these solid wastes.

Environmental performance of unfired bricks produced from co-disposal of mine tailings and municipal solid waste incineration fly ash based on comprehensive leaching tests.

The potential leaching of heavy metals is a crucial concern for construction materials produced from solidification/stabilization (S/S) treatment of wastes. This study comprehensively evaluated the leaching characteristics of heavy metals from the unfired bricks produced from co-disposal of Pb-Zn mine tailings and municipal solid waste incineration fly ash using batch, sequential, and semi-dynamic leaching tests. The results show that S/S treatment drastically reduced the leachability of heavy metals from the unfired bricks through lowering their distribution in the acid-soluble fraction. The effective diffusion coefficients of heavy metals within unfired bricks were all below 1.55 × 10-13 cm2/s, which is indicative of low mobility in the environment. The release of heavy metals from the unfired bricks was primarily governed by diffusion and dissolution. Slaking treatment of fly ash significantly reduced the leaching of heavy metals from the unfired bricks due to their improved structural integrity and compactness, which minimizes the surface area in the solid matrix accessible by the leaching medium. The leachability indices of heavy metals within the unfired bricks ranged from 13.12 to 18.10, suggesting that they are suitable for "controlled utilization" in specific scenarios. Compared to untreated mine tailings, converting them into unfired bricks could reduce the releases of heavy metals by several to hundreds of folds. These findings demonstrate that S/S can be an effective and sustainable strategy for co-disposal of mining tailings and incineration fly ash to produce construction materials with sound long-term environmental performance.

Mechanism and effectiveness of enzymatically induced phosphate precipitation (EIPP) in stabilizing coexisting lead, zinc, and cadmium in tailings.

Lead-zinc (Pb-Zn) tailings ponds carry the risk of multiple heavy metals (HMs) contamination and pile destabilization. This poses requirements for in-situ applicable, low-distribution, and effective stabilization/solidification (S/S) methods. For this, the novel enzymatically induced phosphate precipitation (EIPP) method was implemented in this study. Its mechanism and performance on stabilization of composite Pb, Zn, and cadmium (Cd) in tailings were explored and evaluated under typical erosion conditions for the first time. Results show that the EIPP stabilized HMs by chemically transforming the unstable carbonate-bound HMs to stable phosphate precipitates and by physically encapsulating tailings particles with newberyite precipitates. The stabilization effect on the three HMs was ranked as Pb > Zn > Cd. Comparing magnesium resources for the EIPP reactants, the EIPP utilizing Mg(CH3COO)2 was more effective at decontamination than MgCl2 because its special pre-activation and re-precipitation function enhanced the chemical transformation function of EIPP. The EIPP stabilization was confirmed to reduce simulated acid rain-leachable and bio-extractive HMs by about 90% and 60%, respectively. Under the prolonged acid attack, treated HMs were ultimately leached through the dissolution mechanism. Zn exhibited significant instability in highly acidic conditions (pH = 2.5-3.5), where its cumulative leaching toxicity after long-term dissolution warrants attention. Overall, EIPP presents a novel and effective strategy for on-site mitigation of composite HMs pollution.

Effectiveness of musculoskeletal manipulations in patients with neck pain: a protocol for a systematic review and network meta-analysis.

INTRODUCTION: Neck pain is a common problem that severely affects physical and mental health. While musculoskeletal manipulations are recommended as the first-line treatment for adults with neck pain, the comparative effectiveness of different musculoskeletal manipulations remains unclear. This systematic review and network meta-analysis of randomised controlled trials (RCTs) will compare the effectiveness of different types of musculoskeletal manipulations, with the overarching aim of guiding clinical practice. METHODS AND ANALYSIS: Two independent reviewers will search four English electronic databases (Web of Science, Cochrane Library, EMBASE, PubMed) and three Chinese electronic databases (China National Knowledge Infrastructure, China Science and Technology Journal Database, Wanfang) for relevant RCTs published from 1 January 2013 to 30 April 2023. The Clinical Trials Registry (ClinicalTrials.gov) will be searched for completed but unpublished RCTs. English and Chinese will be used to search English databases and Chinese databases, respectively. RCTs of musculoskeletal manipulations for adults (aged ≥18 years) with neck pain will be considered eligible for inclusion. A pairwise meta-analysis and network meta-analysis will be performed, and pooled risk ratios, standardised mean differences and 95% CIs will be determined. ETHICS AND DISSEMINATION: Ethics approval is not required as this study is a literature review. The results of this review will be published in peer-reviewed journals or disseminated at conferences. PROSPERO REGISTRATION NUMBER: CRD42023420775.

A bibliometric analysis of autism spectrum disorder signaling pathways research in the past decade.

Background: This study employs bibliometric methods to comprehensively understand the fundamental structure of research about Autism Spectrum Disorder (ASD) Signaling Pathways by examining key indicators such as nations, institutions, journals, authors, and keywords. Methodology: We utilized the WoScc database to retrieve literature relevant to ASD Signaling Pathways published between 2013 and 2023. Through visual analysis and tools like CiteSpace and VosViewer, we explored nations, institutions, journals, authors, and keywords, thereby constructing relevant networks. Results: 26 The study encompasses 1,396 articles, revealing a consistent increase in publications. The United States, China, and Germany are leading nations in this literature. Regarding research institutions, the University of California system and Eric Klann have garnered significant attention due to their substantial contributions to the field of ASD Signaling Pathways. Most relevant research is published in the journal "Molecular Autism." Research interests are concentrated across various themes, including "elevating neuronal ß-catenin levels," "Tunisian children," "Fmr1 knockout (KO) mice," "de novo mutations," "autistic children," "local translation," "propionic acid-induced mouse models," "neurosystems," "glucose metabolism," and "neuronal migration." Future research may emphasize exploring aspects such as gut microbiota, genes, stress, maternal immune activation, memory, and neurodevelopmental disorders of ASD. Conclusion: This study, through bibliometric analysis of key indicators such as nations, institutions, journals, authors, and keywords, provides a comprehensive overview of the current state of research on ASD Signaling Pathways. These investigations predominantly focus on molecular mechanisms, animal model studies, population-based research, and the structure and function of neurosystems. Future research directions are also clearly proposed. First, in-depth research on the genes and neurodevelopmental disorders associated with ASD will continue to reveal the genetic basis and provide support for precise treatments. At the same time, attention to the gut microbiota will help explore its association with ASD, which may provide clues for new treatments. In addition, the relationship between stress and ASD will become the focus of research to understand better the emotional and behavioral characteristics of ASD patients in stressful situations. Maternal immune activation will also be further studied to explore how environmental factors influence the risk and development of ASD. Finally, a deeper understanding of the cognitive functions of patients with ASD, especially memory and learning, will help develop individualized treatment strategies to improve patients' quality of life. These directions will work together and are expected to provide a more comprehensive understanding of Signaling Pathways research in ASD and provide new ideas and opportunities for future intervention and treatment.

Characteristics of iron (hydr)oxides and Cr(VI) retention mechanisms in soils from tropical and subtropical areas of China.

Though both iron (hydr)oxides and soil organic matter (SOM) significantly influence heavy metal behaviors in soils, studies on the characteristics of natural minerals and the synergic effects of the two on Cr(VI) transformation are limited. This study investigated Cr(VI) retention mechanisms in four soils from tropical and subtropical regions of China based on a comprehensive characterization of Fe (hydr)oxides. These soils exhibited varying quantities of hematite, ferrihydrite and goethite, with distinct Al substitution levels and varied exposed crystallographic facets. Adsorption experiments revealed a positive correlation between Fe (hydr)oxide content and Cr(VI) fixation amount on colloid, which was influenced by the mineral types, Al substitution levels and facet exposures. Further, Cr(VI) was sequestered on soil by adsorption and reduction. In soils enriched with crystalline Fe (hydr)oxides, Cr(VI) reduction was primarily governed by SOM, while in soils enriched with poorly crystalline Fe (hydr)oxides, mineral-associated Fe(II) also contributed to Cr(VI) reduction. Aging experiments demonstrated that SOM and mineral-associated Fe(II) expedited Cr (VI) passivation and diminished the Cr leaching. These results improve our understanding of natural Fe (hydr)oxide structures and their impact on Cr(VI) behavior in soils, and shed light on complex soil-contaminant interactions and remediation of Cr(VI) polluted soils.

Effects of Tuina targeting different body parts on the behaviors and gut microflora of autistic spectrum disorder rat models / 数字中医药（英文）

Objective @#To investigate the effects of Tuina targeting different body parts on the behaviors and gut microflora of rat models with valproic acid (VPA)-induced autistic spectrum disorder(ASD).@*Methods@#Twenty female Sprague Dawley (SD) rats with 12.5 d of pregnancy were randomly divided into VPA model group [intraperitoneal injection of VPA (600 mg/kg), n = 15] and saline group (intraperitoneal injection of equal amount of normal saline, n = 5). The offspring male rats injected with saline were secleted as control group. The offspring male rats injected with VPA were randomly divided into VPA, dorsal, and abdominal groups (n = 7 in each group). On the 21st day after birth, three-chamber social test, open field test, and marbleburying test were carried out to observe the social abilities, anxiety behaviors, and stereotypical behaviors of rats in the four groups. Rats in dorsal and abdominal groups underwent Tuina for 14 d, twice a day. On the 35th day, behavioral tests were conducted again, and intestinal contents were taken for species composition and structural analysis, as well as marker and differential species analysis.@*Result@#(i) According to behavioral observations, compared with VPA group, the social and movement time in the central open field of rats in dorsal group increased significantly (P <0.05), and the number of buried marbles decreased markedly (P < 0.01), indicating improvement on their social abilities, anxiety behaviors, and stereotypical behaviors as consequences of dorsal Tuina; and the number of buried marbles was reduced as well in abdominal group when compared with VPA group (P < 0.05), suggesting the improvement on their stereotypical behaviors following abdominal Tuina. In the marble-burying test, the number of marbles buried in dorsal group was less than in abdominal group, and the stereotypical behaviors were improved more significantly (P < 0.05), and there were no significant differences in the three-chamber social and open field tests between the two groups (P >0.05). (ii) In accordance with intestinal microflora detection results, compared with VPA group, both dorsal and abdominal groups showed increased richness (P < 0.05) and elevated diversity (P < 0.05 in dorsal group and P < 0.01 in abdominal group) in intestinal microflora. The results of differential analysis indicated that at the phylum level, compared with VPA group, the relative abundance of Firmicutes in rats in abdominal group showed a significant reduction trend (P < 0.05); at the genus level, compared with VPA group, the relative abundance of Lactobacillus in rats in dorsal and abdominal groups decreased significantly (P < 0.05). Dorsal group also showed significant increase in the genus Blautia in the analysis of marker species comparedwith VPA group (P < 0.05).@*Conclusion@#Tuina impacted the behavior and gut microflora structure of ASD model rats. Dorsal intervention had a significant effect on social abilities, anxiety behaviors, and stereotypical behaviors of ASD model rats, while abdominal intervention only had an obvious effect on stereotypical behaviors. Both dorsal and abdominal interventions increased the richness and diversity of gut microflora of ASD model rats, with abdominal intervention improving the intestinal microbial diversity more significantly and resulting in a more uniform species distribution.

Effect of COVID-19 on autism spectrum disorders: A bibliometric analysis based on original articles.

BACKGROUND: The objective of this bibliometric inquiry was to scrutinize domains that delve into the repercussions of the 2019 coronavirus disease (COVID-19) pandemic on individuals afflicted with autism spectrum disorder (ASD), worldwide scholarly findings of interrelated research, and forthcoming trajectories. METHODS: To conduct a literature analysis, use the web of science core collection database, search for ASD and COVID-19-related literature published Utilize CiteSpace and VosViewer to visually analyze documents and create networks of authors, organizations. The CiteSpace and VosViewer to visually analyze documents and create networks of authors, organizations, countries, and keywords. RESULTS: This study collected 771 papers and shows an increasing trend in publications. The United States had the most relevant literature (281), followed by the United Kingdom (115) and Italy (76). The United States had the most relevant literature (281), followed by the United Kingdom (115) and Italy (76). The University of London had the most papers (53, 6.87%), and Happe_Francesca was the most productive researcher (6). J AUTISM DEV DISORD was the main journal for research on the impact of COVID-19 on ASD, with 22 related articles. Keyword co-occurrence analysis has revealed that "parenting stress," "enhancing adherence," "acute stress disorder," "COVID-19 Italian lockdown," "neurodevelopmental disorder," and "occupational therapy" have garnered significant attention recently. Notably, the burst keywords suggest that "interventions," "qualitative research," "Disabilities Monitoring Network," "neurodevelopmental disabilities," "perceived stress," and "barriers" are potential areas of investigation for future research. CONCLUSION: This bibliometric analysis delineates the fundamental structure for assessing the impact of COVID-19 on ASD by scrutinizing crucial indicators such as Our analysis reveals that COVID-19 impact on autism has garnered the interest of an Future research could explore the stress, anxiety, and strategies for individuals with ASD and their The use of telemedicine can be studied in depth, as a new idea for ASD diagnosis and intervention training, it is worthwhile. The use of telemedicine can be studied in depth, as a new idea for ASD diagnosis and intervention training, it is worth exploring, such as Disabilities Monitoring Network, etc.

Exploring the migration and transformation behaviors of heavy metals and ammonia nitrogen from electrolytic manganese residue to agricultural soils through column leaching test.

Heavy metals (HMs) and ammonia nitrogen (AN) leaching from electrolytic manganese residue (EMR) result in the contamination of agricultural soils and water bodies. Batch and column leaching tests were conducted to simulate the release of HMs and AN in EMR during precipitation, as well as their migration and transformation in agricultural soils. The results show that Mn, AN, Cd, Ni, and Zn present in the EMR had high acid soluble fraction (un-fixed AN) content, and the leachability of Mn and AN was significantly higher than that of other hazardous elements. The cumulative release of hazardous elements in the EMR stockpile was well-fitted (R2 > 0.95) by the HILL model. Significant HMs and AN accumulated in the agricultural soils after contamination from the EMR leachate. The pollution degree of HMs in agricultural soils was ranked as Mn > Ni > Pb ≈ Zn ≈ Cr > Cd. The acid soluble fraction (un-fixed AN) content of Mn, Ni, Zn, and AN in agricultural soils increased significantly. The risk assessment code shows that the risk level of Mn in agricultural soils changed from medium to high; Ni and Zn in surface soils changed from low to medium. These results indicated that the leaching from EMR would significantly increase the ecological risk of HMs in surrounding agricultural soils, and the large release of AN would pose a great threat to aquatic systems if not properly addressed.

Bibliometric Analysis of Research Trends on Tuina Manipulation for Neck Pain Treatment Over the Past 10 Years.

Tuina is an effective treatment for neck pain (NP). However, there has been no bibliometric analysis of the global application and emerging trends of tuina performed for NP. Therefore, this study aimed to provide an overview of the current state and future trends in the field. Articles about tuina for NP, published from January 1, 2013, to January 1, 2023, were searched in the Web of Science Core Collection database. CiteSpace (6.1.R6) and VOSviewer (1.6.18) software were used to analyze annual trends in literature posts, countries, institutions, authors, cited references, and knowledge graphs of keyword co-occurrence, clustering, and burst using standard bibliometric indicators. The final analysis comprised 505 valid documents. The results demonstrate that the number of articles in the field of tuina therapy for NP has gradually increased over the years, showing the most active countries, institutions, journals, and authors. There were 323 keywords in the field, 322 research authors, and 292 research institutions, with the USA having the most publications (n = 140). The most published institution is Vrije University Amsterdam, and the most published journal is the Cochrane Database of Systematic Reviews. Peter R Blanpied is the most influential and most-cited author. Interventions (dry needling, massage therapy, and muscle energy techniques), common treatment sites for NP (upper trapezius), and complications (cervicogenic headache) are the top three frontiers mentioned in the field of tuina research for NP. The bibliometric study showed the current status and trends in clinical research on treating patients with NP using tuina, which may help researchers identify topics of interest and scope for future research in this field.

Unraveling the cation adsorption of geopolymer binder: A molecular dynamics study.

Geopolymers play a significant role in remediation of heavy metal contamination and are attracting increasing interests. Sodium aluminosilicate hydrate (NASH) is the prime hydration substance of geopolymers which exhibits excellent adsorption capacity, however, the mechanism of metal cation adsorption at the NASH interface remains unclear. In this study, the adsorption behavior of cations at the NASH interface was investigated in depth, and the effects of Si/Al ratios, ion concentration and ion type on adsorption behavior were also analyzed. Furthermore, three Si/Al ratio models of NASH gel were modified and developed by molecular dynamics simulation, and validated by experiments. The result showed that electrostatic attraction and ion exchange played the major role in adsorbing three cations on the surface of NASH gel. For cations with the same charge number, ionic radius was inversely proportional to the cation exchange and adsorption capacity. Cations with lower ionic potential, among those with different charge numbers, were easier to be adsorbed onto the NASH surface. Therefore, the adsorption capacity of NASH for the three adsorbents was in the order of Na+ > Cs+ > Pb2+. The adsorption capacity of NASH gel for cations increased with the increasing of Al/Si and decreased with the increasing of cation concentration, which was attributed to the increased electrostatic attraction on the NASH surface and the limited number of adsorption sites. The derived microstructure and dynamics information are beneficial for profoundly understanding the adsorption mechanisms of geopolymers on cations.

Physicochemical and pozzolanic properties of municipal solid waste incineration fly ash with different pretreatments.

Swelling caused by gas generated from municipal solid waste incineration fly ash (MSWIFA) when it is mixed with alkali limits its uses. Besides, the leaching of anion salts and heavy metals contained in MSWIFA poses a high risk to environment. This study presents the feasibility of a one-step alkaline washing, one-step thermal quenching and two-step combination of alkaline washing and thermal quenching pretreatment methods in altering the key properties of MSWIFA for promoting its reusability. It was found that apart from H2(gas), NH3(gas) was also generated during the alkaline washing of the MSWIFA. Besides, pretreatments led to the reduction in particle size, the increase in pore volume and specific surface area of the MSWIFA, as well as the removal of chloride and sulfate anions. All the pretreatment methods were effective in reducing leaching of heavy metals to below levels of nonhazardous waste except Cd and Pb with alkaline washing. Furthermore, both the chemical Frattini test and the mechanical activity index test showed improvement in pozzolanic activities of the MSWIFA after the pretreatments. Overall, the combined pretreatment method was most effective in eliminating gas emission, and reducing leaching of metal ions and anions from the ash, while enhancing the pozzolanic activity of the ash.

Recycling of water treatment sludge in concrete: The role of water-binder ratio from a nanoscale perspective.

For eutrophic water bodies, potassium permanganate is an effective pre-oxidant to remove algae and its residue in water treatment sludge. Recycling water treatment sludge in concrete is an environmentally friendly and high-value utilization measure. However, little research has been done on the effect of manganese-rich drinking water sludge ash (DWSA) on concrete. The effect of water-binder ratio (w/b) on strength, shrinkage and microstructural characteristics of concrete containing DWSA was investigated, and the structural behavior was explained from a nanoscale perspective. The results show that recycling 10 % DWSA in concrete improved the strength and shrinkage resistance of the samples. Reducing the w/b effectively increased the strength of DWSA-modified concrete and reduced the shrinkage deformation. The paste with high w/b had higher contents of non-evaporated water and calcium hydroxide, as well as higher reaction degree of DWSA. Nanoscale characterization shows that reducing the w/b reduced the volume fraction of pore and unhydrated phases in the matrix and increased the proportion of high-density C-S-H. Meanwhile, reducing the w/b also reduced the interfacial transition zone width of DWSA-modified concrete. Recycling DWSA in concrete effectively reduced the total carbon footprint and cost of the mixture. The combined application of reducing the w/b and incorporating DWSA effectively improved the economic and environmental benefits of concrete material. For the concrete modified with 10 % DWSA (w/b = 0.3), its cost and carbon emissions are reduced by 14 %-21 % and 19 %-25 % compared with the reference sample, respectively. Overall, this study reveals the action mechanism of DWSA in cement system at different w/b from nanoscale perspective, and gives a new insight on determining the optimal w/b in full-scale application of DWSA concrete.

Solidification and stabilization of Pb-Zn mine tailing with municipal solid waste incineration fly ash and ground granulated blast-furnace slag for unfired brick fabrication.

The mismanaged and abandoned mine tailings are an important source of heavy metal pollution in the mining regions, and there is a significant need to develop technically, environmentally, and economically feasible and sustainable solutions to manage them. This study explored the solidification and stabilization of the tailing from an abandoned Pb-Zn mine using municipal solid waste incineration fly ash (MSWIFA) blended with ground granulated blast-furnace slag (GGBFS) for fabricating unfired bricks, and systematically characterized the products' mechanical and environmental performance. Various hydration products, such as ettringite, portlandite, and hydrotalcite, were formed in the unfired bricks in the solidification and stabilization process, which enhance the physical strength of unfired bricks and help immobilize the heavy metals. Slaking treatment of MSWIFA significantly increased the mechanical strength, reduced the water absorption, and improved the durability of unfired bricks, with the product prepared from MSWIFA with 7-day slaking exhibiting the highest unconfined compressive strength (12.3 MPa) after 56 days of curing. The concentrations of As (0.35-1.49 µg/L), Cd (0.35-0.70 µg/L), Cr (1.38-9.40 µg/L), Cu (2.28-5.87 µg/L), Ni (0.16-2.24 µg/L), Pb (0.16-59.80 µg/L), and Zn (1.60-10.80 µg/L) in the leachates of unfired bricks were below the relevant regulatory limits for surface water and groundwater. Converting the mine tailing (with MSWIFA and GGBFS) to different types of unfired bricks could yield economic payback in the range of 283.7-306.5 Yuan per ton. Replacing cement with MSWIFA blended with GGBFS in the solidification and stabilization treatment could save about 0.15 ton of cement per ton of mine tailing disposed, which avoids significant energy use and carbon dioxide emissions. These findings demonstrate that utilization of mine tailings and industrial wastes to fabricate unfired bricks is a promising way of reusing such wastes and controlling the associated pollution, which also brings significant economic benefit and improves environmental sustainability.

Stabilization and strengthening of chromium(VI)-contaminated soil via magnesium ascorbyl phosphate (MAP) and phytase addition.

Cr(VI) contamination of soil threatens the environment and reduces soil strength. Therefore, both Cr(VI) stabilization and soil reinforcement should be considered in site remediation for future construction. This study investigated a biochemical treatment process using magnesium ascorbyl phosphate (MAP) and phytase. MAP was hydrolyzed via phytase catalysis to produce ascorbic acid (AA) and MgHPO4·3H2O precipitation. The AA reduced Cr(VI) into low-toxic Cr(III), which precipitated as Cr(OH)3 and CrPO4. More than 90% of the 500 mg/kg Cr(VI) in soil was reduced by 5% MAP (wt% of soil) and 1% phytase (vol/vol of soil water) doses at the geotechnically optimal soil moisture content of 16.8%. The MgHPO4·3H2O precipitates filled soil pores and enhanced the unconfined compression strength of treated soil by more than two times. This research reports a novel and practical enzymatically induced phosphate precipitation process for the remediation of Cr(VI)-contaminated soil.