Binding between Cu2+/Zn2+ and aged polyethylene and polyethylene terephthalate microplastics in swine wastewaters: Adsorption behavior, and mechanism insights.

Microplastics (MPs) have aroused growing environmental concerns due to their biotoxicity and vital roles in accelerating the spread of toxic elements. Illuminating the interactions between MPs and heavy metals (HMs) is crucial for understanding the transport and fate of HM-loaded MPs in specific environmentally relevant scenarios. Herein, the adsorption of copper (Cu2+) and zinc (Zn2+) ions over polyethylene (PE) and polyethylene terephthalate (PET) particulates before and after heat persulfate oxidation (HPO) treatment was comprehensively evaluated in simulated and real swine wastewaters. The effects of intrinsic properties (i.e., degree of weathering, size, type) of MPs and environmental factors (i.e., pH, ionic strength, and co-occurring species) on adsorption were investigated thoroughly. It was observed that HPO treatment expedites the fragmentation of pristine MPs, and renders MPs with a variety of oxygen-rich functional groups, which are likely to act as new active sites for binding both HMs. The adsorption of both HMs is pH- and ionic strength-dependent at a pH of 4-6. Co-occurring species such as humic acid (HA) and tetracycline (TC) appear to enhance the affinity of both aged MPs for Cu2+ and Zn2+ ions via bridging complexation. However, co-occurring nutrient species (e.g., phosphate and ammonia) demonstrate different impacts on the adsorption, improving uptake of Cu2+ by precipitation while lowering affinity for Zn2+ owing to the formation of soluble zinc-ammonia complex. Spectroscopic analysis indicates that the dominant adsorption mechanism mainly involves electrostatic interactions and surface complexation. These findings provided fundamental insights into the interactions between aged MPs and HMs in swine wastewaters and might be extended to other nutrient-rich wastewaters.

Phosphorus recovery via struvite crystallization in batch and fluidized-bed reactors: Roles of microplastics and dissolved organic matter.

Struvite crystallization, a promising technology for nutrient recovery from wastewater, is facing considerable challenges due to the presence of emerging contaminants such as microplastics (MPs) ubiquitously found in wastewater. Here, we investigate the roles of MPs and humic acid (HA) in struvite crystallization in batch and fluidized-bed reactors (FBRs) using synthetic and real wastewater with a Mg:N:P molar ratio of 1:3:(1-1.3) at an initial pH of 11. Batch reactor (BR) experiment results show that MPs expedited the nucleation and growth rates of struvite (e.g., the rate of crystal growth in the presence of 30 mg L-1 of polyethylene terephthalate (PET) was 1.43 times higher than that in the blank system), while HA hindered the formation of struvite. X-ray diffraction and the Rietveld refinement analysis revealed that the presence of MPs and HA can result in significant changes in phase compositions of the reclaimed precipitates, with over 80 % purity of struvite found in the precipitates from suspensions in the presence of 30 mg L-1 of MPs. Further characterizations demonstrated that MPs act as seeds of struvite nucleation, spurring the formation of well-defined struvite, while HA favors the formation of newberyite rather than struvite in both reactors. These findings highlight the need for a more comprehensive understanding of the interactions between emerging contaminants and struvite crystallization processes to optimize nutrient recovery strategies for mitigating their adverse impact on the quality and yield of struvite-based fertilizers. ENVIRONMENTAL IMPLICATION: The presence of microplastics in wastewater poses a significant challenge to struvite crystallization for nutrient recovery, as it accelerates nucleation and growth rates of struvite crystals. This can lead to changes in the phase compositions of the reclaimed precipitates, with implications for the quality and yield of struvite-based fertilizers. Additionally, the presence of humic acid hinders the formation of struvite, favoring the formation of other minerals like newberyite. Understanding the interactions between emerging contaminants and struvite crystallization processes is crucial for optimizing nutrient recovery strategies and mitigating the environmental impact of these contaminants on water quality and struvite-based fertilizers.

Structural characteristics and gelling properties of citrus pectins after chemical and enzymatic modifications: Conformation plays a vital role in Ca2+-induced gelation.

Due to the excellent health benefits of rhamnogalacturonan I (RG-I)-enriched pectin, there has been increasing research interest in its gelling properties. To elucidate its structure-gelation relationship, chemical modifications were used to obtain RG-I-enriched pectin (P11). Then, enzymatic modification was performed to obtain debranched pectins GP11 and AP11, respectively. The effects of RG-I side chains on structural characteristics (especially spatial conformation) and gelling properties were investigated. Among the low-methoxylated pectins (LMPs), AP11, with a loose conformation (Dmax 52 nm) showed the poorest gelling, followed by GP11. In addition to primary structure, spatial conformation (Dmax and Rg) also showed strong correlations (r2 > 0.8) with gelation. We speculate that compact conformation may shorten distance between pectin chains and reduces steric hindrance, contributing to formation of strong gel network. This is particularly important in LMPs with abundant side chains. The results provide novel insights into relationship between spatial conformation and gelling properties of RG-I-enriched pectin.

Current scenario of pyrazole hybrids with anti-breast cancer therapeutic applications.

Breast cancer stands as the leading cause of cancer-related deaths among women globally, but current therapy is restricted to the serious adverse effects and multidrug resistance, necessitating the exploration of novel, safe, and efficient anti-breast cancer chemotherapeutic agents. Pyrazoles exhibit excellent potential for utilization as effective anti-breast cancer agents due to their ability to act on various biological targets. Particularly, pyrazole hybrids demonstrated the advantage of targeting multiple pathways, and some of them, which are exemplified by larotrectinib (pyrazolo[1,5-a]pyrimidine hybrid), can be applied for breast cancer therapy. Thus, pyrazole hybrids hold great promise as useful therapeutic interventions for breast cancer. The aim of this review is to summarize the current scenario of pyrazole hybrids with in vitro and/or in vivo anti-breast cancer potential, along with the modes of action and structure-activity relationships, covering articles published from 2020 to the present, to streamline the development of rational, effective and safe anti-breast cancer candidates.

Oxygen-containing functional groups in Fe3O4@three-dimensional graphene nanocomposites for enhancing H2O2 production and orientation to 1O2 in electro-Fenton.

In electro-Fenton (EF), development of a bifunctional electrocatalyst to realize simultaneous H2O2 generation and activation efficiently for generating reactive species remains a challenge. In particular, a nonradical-mediated EF is more favorable for actual wastewater remediation, and deserves more attention. In this study, three-dimensional graphene loaded with Fe3O4 nanoparticles (Fe3O4@3D-GNs) with abundant oxygen-containing functional groups (OFGs) was synchronously synthesized using a NaCl-template method and served as a cathode to establish a highly efficient and selective EF process for contaminant degradation. The amounts of OFGs can be effectively modulated via the pyrolysis temperature to regulate the 2e- oxygen reduction reaction activity and reactive oxygen species (ROS) production. The optimized Fe3O4@3D-GNs synthesized at 750 °C (Fe3O4@3D-GNs-750) with the highest -C-O-C and -C꞊O group ratios exhibited the maximum H2O2 and 1O2 yields during electrocatalysis, thus showing remarkable versatility for eliminating organic contaminants from surface water bodies. Experiments and theoretical calculations have demonstrated the dominant role of -C-O-C in generating H2O2 and the positive influence of -C꞊O sites on the production of 1O2. Moreover, the surface-bound Fe(II) favors the generation of surface-bound •OH, which steers a more favorable oxidative conversion of H2O2 to 1O2. Fe3O4@3D-GNs were proven to be less pH-dependent, low-energy, stable, and recyclable for practical applications in wastewater purification. This study provides an innovative strategy to engineer active sites to achieve the selective electrocatalysis for eliminating pollution and reveals a novel perspective for 1O2-generation mechanism in the Fenton reaction.

Investigation into the Dissolution Kinetics of Different MgO Desulfurizers in Flue Gas Desulfurization.

The paper introduced hydrophilic functional groups on the surface of the MgO desulfurizer to improve its dispersion and hydrophilicity on the basis of reducing the particle size of the MgO desulfurizer to the nanometer level. Mechanical grinding technology was used to improve the traditional two-step method to lay the foundation for its large-scale production. The stability test showed that the ζ potential of the 5 wt % modified MgO desulfurizer was greater than 50 mV with 30 days of storage, and the sedimentation rate was not more than 7%. The dissolution reactivity and kinetics experiments showed that the decrease of particle size and the increase of hydrophilicity and dispersion were conducive to accelerating the dissolution rate of the MgO desulfurizer and reducing the apparent activation energy. Meanwhile, the good dissolution rate of the modified MgO nanofluids prepared by the improved method could reduce the liquid film mass transfer resistance and prolonged the penetration time.

Sulfur-containing iron carbon nanocomposites activate persulfate for combined chemical oxidation and microbial remediation of petroleum-polluted soil.

In this study, sulfur-containing iron carbon nanocomposites (S@Fe-CN) were synthesized by calcining iron-loaded biomass and utilized to activate persulfate (PS) for the combined chemical oxidation and microbial remediation of petroleum-polluted soil. The highest removal efficiency of total petroleum hydrocarbons (TPHs) was achieved at 0.2% of activator, 1% of PS and 1:1 soil-water ratio. The EPR and quenching experiments demonstrated that the degradation of TPHs was caused by the combination of 1O2,·OH, SO4·-, and O2·-. In the S@Fe-CN activated PS (S@Fe-CN/PS) system, the degradation of TPHs underwent two phases: chemical oxidation (days 0 to 3) and microbial degradation (days 3 to 28), with kinetic constants consistent with the pseudo-first-order kinetics of chemical and microbial remediation, respectively. In the S@Fe-CN/PS system, soil enzyme activities decreased and then increased, indicating that microbial activities were restored after chemical oxidation under the protection of the activators. The microbial community analysis showed that the S@Fe-CN/PS group affected the abundance and structure of microorganisms, with the relative abundance of TPH-degrading bacteria increased after 28 days. Moreover, S@Fe-CN/PS enhanced the microbial interactions and mitigated microbial competition, thereby improving the ability of indigenous microorganisms to degrade TPHs.

The microbial biosynthesis of noncanonical terpenoids.

Terpenoids are a class of structurally complex, naturally occurring compounds found predominantly in plant, animal, and microorganism secondary metabolites. Classical terpenoids typically have carbon atoms in multiples of five and follow well-defined carbon skeletons, whereas noncanonical terpenoids deviate from these patterns. These noncanonical terpenoids often result from the methyltransferase-catalyzed methylation modification of substrate units, leading to irregular carbon skeletons. In this comprehensive review, various activities and applications of these noncanonical terpenes have been summarized. Importantly, the review delves into the biosynthetic pathways of noncanonical terpenes, including those with C6, C7, C11, C12, and C16 carbon skeletons, in bacteria and fungi host. It also covers noncanonical triterpenes synthesized from non-squalene substrates and nortriterpenes in Ganoderma lucidum, providing detailed examples to elucidate the intricate biosynthetic processes involved. Finally, the review outlines the potential future applications of noncanonical terpenoids. In conclusion, the insights gathered from this review provide a reference for understanding the biosynthesis of these noncanonical terpenes and pave the way for the discovery of additional unique and novel noncanonical terpenes. KEY POINTS: •The activities and applications of noncanonical terpenoids are introduced. •The noncanonical terpenoids with irregular carbon skeletons are presented. •The microbial biosynthesis of noncanonical terpenoids is summarized.

Application of dirty-acid wastewater treatment technology in non-ferrous metal smelting industry: Retrospect and prospect.

Dirty-acid wastewater (DW) originating from the non-ferrous metal smelting industry is characterized by a high concentration of H2SO4 and As. During the chemical precipitation treatment, a significant volume of arsenic-containing slag is generated, leading to elevated treatment expenses. The imperative to address DW with methods that are cost-effective, highly efficient, and safe is underscored. This paper conducts a comprehensive analysis of three typical methods to DW treatment, encompassing technical principles, industrial application flow charts, research advancements, arsenic residual treatment, and economic considerations. Notably, the sulfide method emerges as a focal point due to its minimal production of arsenic residue and the associated lowest overall treatment costs. Moreover, in response to increasingly stringent environmental protection policies targeting new pollutants and carbon emissions reduction, the paper explores the evolving trends in DW treatment. These trends encompass rare metal and sulfuric acid recycling, cost-effective H2S production methods, and strategies for reducing, safely disposing of, and harnessing resources from arsenic residue.

Identification of immune-related gene signatures for chronic obstructive pulmonary disease with metabolic syndrome: evidence from integrated bulk and single-cell RNA sequencing data.

Chronic obstructive pulmonary disease (COPD) is closely related to innate and adaptive inflammatory immune responses. It is increasingly becoming evident that metabolic syndrome (MetS) affects a significant portion of COPD patients. Through this investigation, we identify shared immune-related candidate biological markers. The Weighted Gene Co-Expression Network Analysis (WGCNA) was utilized to reveal the co-expression modules linked to COPD and MetS. The commonly expressed genes in the COPD and MetS were utilized to conduct an enrichment analysis. We adopted machine-learning to screen and validate hub genes. We also assessed the relationship between hub genes and immune cell infiltration in COPD and MetS, respectively. Moreover, associations across hub genes and metabolic pathways were also explored. Finally, we chose a single-cell RNA sequencing (scRNA-seq) dataset to investigate the hub genes and shared mechanisms at the level of the cells. We also applied cell trajectory analysis and cell-cell communication analysis to focus on the vital immune cell we were interested in. As a result, we selected and validated 13 shared hub genes for COPD and MetS. The enrichment analysis and immune infiltration analysis illustrated strong associations between hub genes and immunology. Additionally, we applied metabolic pathway enrichment analysis, indicating the significant role of reactive oxygen species (ROS) in COPD with MetS. Through scRNA-seq analysis, we found that ROS might accumulate the most in the alveolar macrophages. In conclusion, the 13 hub genes related to the immune response and metabolism may serve as diagnostic biomarkers and treatment targets of COPD with MetS.

Remarkable adsorption of As(V) by Fe3+ and Mg2+ modified alginate porous beads (Fe/Mg-SA) via a facile method.

Although sodium alginate (SA) is frequently utilized because of its good gelling properties, the substance's dearth of adsorption active sites prevents it from effectively removing heavy metals. Herein, SA was used as the base material to form a cross-linked structure with Fe3+ and Mg2+, and gel beads with a diameter of 2.0 ± 0.1 mm with specific adsorption on As(V) were synthesized as adsorbent (Fe/Mg-SA). Fe/Mg-SA was systematically characterized, and its adsorption properties were investigated by varying several conditions. Fe/Mg-SA had a wide pH application range. The adsorption kinetics revealed that a quasi-secondary kinetic model was followed. The adsorption process is linked to the complexation of hydroxyl and AsO43-, chemisorption predominated the adsorption process. The maximal adsorption capacity of Fe/Mg-SA is determined by fitting the Langmuir model to be 37.4 mg/g. Compared to other adsorbents, it is simpler to synthesis, more effective and cheaper. Each treatment of 1 m3 wastewater of Fe/Mg-SA only costs ¥ 38.612. The novel gel beads synthesized provides a better option for purifying groundwater contaminated with As(V).

Investigation into the Enhancement of Gas-Liquid Mass Transfer of Absorption of H2S by MDEA with Carbon Quantum Dots.

Although the addition of fine particles can enhance mass transfer, the stability of suspension is still a challenge. Responding to this, this study introduced carbon quantum dots (CQDs) with good hydrophilicity into a desulfurizer. N-doped carbon quantum dots (N-CQDs) were prepared by the hydrothermal method and characterized by TEM, FT-IR, and XPS. The stability and rheological properties of MDEA-based CQD solutions with different concentrations were studied. CQD solutions with low concentrations showed good stability, and the viscosity of CQD solutions was positively correlated with concentration and inversely correlated with temperature. The desulfurization experiment showed that the desulfurization effect and mass transfer enhancement of MDEA-based CQD solutions were coinfluenced by the viscosity and concentration of the solution; 0.01 vol % CQD solution had the best desulfurization effect, and the mass transfer coefficient was 0.66 mol/(m3h kPa), which increased by 26.61% compared to the base solution.

Deep insight on mechanism and contribution of arsenic removal and heavy metals remediation by mechanical activation phosphogypsum.

Arsenic-containing wastewater and arsenic-contaminated soil can cause serious environmental pollution. In this study, phosphogypsum with partial mechanical activation of calcium oxide was used to prepare a new phosphogypsum-based passivate (Ca-mPG), and its remediation performance on arsenic-contaminated soil was evaluated in terms of both effectiveness and microbial response. The results showed that the optimum conditions for the preparation of the passivate were optimized in terms of single factor and response surface with a ball milling speed of 200 r/min, a material ratio of 6:4 and a ball milling time of 4 h. Under these conditions, the adsorption capacity was 37.75 mg/g. The leaching concentration of arsenic (As) in the contaminated soil after Ca-mPG modification decreased from 25.75 µg/L to 5.88 µg/L, which was lower than the Chinese national standard (GB/T 5085.3-2007); Ca-mPG also showed excellent passivation effect on other heavy Metals (copper, nickel, cadmium, zinc). In addition, As-resistant bacteria and passivators work together to promote the stabilization effect of contaminants during the remediation of As-contaminated soil. The mechanisms of Cu, As(III)/As(V), Zn, Cd, and Ni removal were related to ion exchange, electrostatic adsorption of substances on heavy metals, calcium binding to other substances to produce precipitation; and microbially induced stabilization of HMs, oxidized. Overall, this study demonstrates an eco-friendly "waste-soil remediation" strategy to solve problems associated with solid waste reuse and remediation of HM-contaminated soils.

Remediation of arsenic contaminated water and soil using mechanically (ball milling) activated and pyrite-amended electrolytic manganese slag.

With the development of industry, heavy metal (HM) pollution of soil has become an increasingly serious problem. Using passivators made of industrial by-products to immobilize HMs in contaminated soil is a promising in-situ remediation technology. In this study, the electrolytic manganese slag (EMS) was modified into a passivator (named M-EMS) by ball milling, and the effects of M-EMS on adsorption of As(V) in aquatic samples and on immobilization of As(V) and other HMs in soil samples were investigated under different conditions. Results demonstrated that M-EMS had a maximum As(V) adsorption capacity of 65.3 mg/g in the aquatic samples. Adding M-EMS to the soil reduced the leaching of As (from 657.2 to 319.8 µg/L) and other HMs after 30 d of incubation, reduced the bioavailability of As(V) and improved the quality and microbial activity of the soil. The mechanism for M-EMS to immobilize As in the soil are complex reactions, ion exchange reaction with As and electrostatic adsorption. This work provides new ideas of using waste residue matrix composites for sustainable remediation of Arsenic in the aquatic environment and soil.

Gelling properties of lysine-amidated citrus pectins: The key role of pH in both amidation and gelation.

The amidation of pectin by amino acids has been widely applied due to its safety and excellent gelling properties. This study systematically examined the effects of pH on the gelling properties of lysine-amidated pectin during amidation and gelation. Pectin was amidated over the range of pH 4-10, and the amidated pectin obtained at pH 10 showed the highest degree of amidation (DA, 27.0 %) due to the de-esterification, electrostatic attraction, and the stretching state of pectin. Moreover, it also exhibited the best gelling properties due to its greater numbers of calcium-binding regions (carboxyl groups) and hydrogen bond donors (amide groups). During gelation, the gel strength of CP (Lys 10) at pH 3-10 first increased and then decreased, with the highest gel strength at pH 8, which was due to the deprotonation of carboxyl groups, protonation of amino groups, and ß-elimination. These results show that pH plays a key role in both amidation and gelation, with distinct mechanisms, and would provide a basis for the preparation of amidated pectins with excellent gelling properties. This will facilitate their application in the food industry.

Simultaneous immobilization of multiple heavy metals in polluted soils amended with mechanical activation waste slag.

Heavy metal soil contamination has become an increasingly serious problem in industrial development. However, industrial byproducts used for remediation are one aspect of green remediation that can contribute to sustainable practices in waste recycling. In this study, electrolytic manganese slags (EMS) were mechanically activated and modified into a passivator (M-EMS), and the heavy metal adsorption performance of M-EMS, heavy metal passivation ability in soil, dissolved organic matter (DOM) change and its effect on the microbial community structure of soil were investigated. The findings revealed that the maximum adsorption capacities of As(V), Cd2+, Cu2+ and Pb2+ were 76.32 mg/g, 301.41 mg/g, 306.83 mg/g and 826.81 mg/g, respectively, indicating that M-EMS demonstrated remarkable removal performance for different heavy metals. The Langmuir model fits Cd2+, Cu2+ and Pb2+ better than the Freundlich model, and monolayer adsorption is the main process. Surface complexation played a major role in the As(V) adsorption's on the surface of metal oxides in M-EMS. The passivation effect was ranked as Pb > Cr > As>Ni > Cd > Cu, with the highest passivation rate of 97.59 % for Pb, followed by Cr (94.76 %), then As (71.99 %), Ni (65.17 %), Cd (61.44 %), and the worst one was Cu (25.17 %). In conclusion, the passivator has the effect of passivation for each heavy metal. The addition of passivating agent can enhance the diversity of microorganisms. Then it can change the dominant flora and induce the passivation of heavy metals through microorganisms. XRD, FTIR, XPS and the microbial community structure of soil indicated that M-EMS can stabilize heavy metals in contaminated soils through four main mechanisms: ion exchange, electrostatic adsorption, complex precipitation and the microbially induced stabilization. The results of this study may provide new insights into the ecological remediation of multiple heavy-metal-contaminated soils and water bodies and research on the strategy of waste reduction and harmlessness by using EMS-based composites in combination with heavy metals in soil.

Advances in the biosynthesis and metabolic engineering of rare ginsenosides.

Rare ginsenosides are the deglycosylated secondary metabolic derivatives of major ginsenosides, and they are more readily absorbed into the bloodstream and function as active substances. The traditional preparation methods hindered the potential application of these effective components. The continuous elucidation of ginsenoside biosynthesis pathways has rendered the production of rare ginsenosides using synthetic biology techniques effective for their large-scale production. Previously, only the progress in the biosynthesis and biotechnological production of major ginsenosides was highlighted. In this review, we summarized the recent advances in the identification of key enzymes involved in the biosynthetic pathways of rare ginsenosides, especially the glycosyltransferases (GTs). Then the construction of microbial chassis for the production of rare ginsenosides, mainly in Saccharomyces cerevisiae, was presented. In the future, discovery of more GTs and improving their catalytic efficiencies are essential for the metabolic engineering of rare ginsenosides. This review will give more clues and be helpful for the characterization of the biosynthesis and metabolic engineering of rare ginsenosides. KEY POINTS: • The key enzymes involved in the biosynthetic pathways of rare ginsenosides are summarized. • The recent progress in metabolic engineering of rare ginsenosides is presented. • The discovery of glycosyltransferases is essential for the microbial production of rare ginsenosides in the future.

Insights into S-doped iron-based carbonaceous nanocomposites with enhanced activation of persulfate for rapid degradation of organic pollutant.

In the work, S-doped iron-based carbon nanocomposites (Fe-S@CN) for activating persulfate (PS) were prepared by calcining iron-loaded sodium lignosulfonate. The characterization revealed that the main substances of Fe-S@CN were FeS and Fe3C, which were distributed on porous carbon nanosheets in rod-like morphology. In the Fe-S@CN/PS system, carbamazepine could be completely removed within 30 min, and the relative contribution of hydroxyl radicals (OH·), sulfate radicals (SO4·-) and total singlet oxygen (1O2) and superoxide radicals (O2·-) for carbamazepine removal were approximated as 8.7%, 19.2% and 72.1%, respectively. Electron paramagnetic resonance spectroscopy demonstrated that S doping promoted the formation of various active species. Compared with the catalyst without S doping, Fe-S@CN exhibited higher activation performance (1.48-fold) for PS due to the enhanced electron transfer rate and facilitated Fe2+/Fe3+ cycle. Density functional theory calculations showed that S doping promoted the binding between the catalyst and PS, and enhanced the overall internal electron density of the catalyst. Fe-S@CN exhibited excellent catalytic performance over a wide pH range (3.0-11.0). The active sites of Fe-S@CN used in the cycling experiments was also largely recovered after thermal regeneration. Overall, this study shows for the first time the impact of SLS as an S dopant on enhanced PS activation.

Advances in the optimization of central carbon metabolism in metabolic engineering.

Central carbon metabolism (CCM), including glycolysis, tricarboxylic acid cycle and the pentose phosphate pathway, is the most fundamental metabolic process in the activities of living organisms that maintains normal cellular growth. CCM has been widely used in microbial metabolic engineering in recent years due to its unique regulatory role in cellular metabolism. Using yeast and Escherichia coli as the representative organisms, we summarized the metabolic engineering strategies on the optimization of CCM in eukaryotic and prokaryotic microbial chassis, such as the introduction of heterologous CCM metabolic pathways and the optimization of key enzymes or regulatory factors, to lay the groundwork for the future use of CCM optimization in metabolic engineering. Furthermore, the bottlenecks in the application of CCM optimization in metabolic engineering and future application prospects are summarized.

Preparation of phosphogypsum-copper smelting slag-based consolidating body with high compressive strength.

Phosphogypsum (PG) is an industrial waste residue produced during the production of phosphoric acid through the wet process. With strong acidity and a large amount of toxic impurities, PG is difficult to reuse. In this study, the solidified body (PG-S) was made by mechanical compression of the mixture of PG, copper smelting slag (CSS), CaO, NaOH, and water. Results indicate that the composition of the material phases in the PG-S samples changed with hydrated calcium silicate and amorphous silicate derivatives were formed during the reaction; Fe and Ca in the material were transformed; and the prepared geopolymer material had a dense internal structure with the materials being cemented to each other. The highest compressive strength of PG-S cured for 28 days could reach 21.3 MPa with a fixation efficiency of PO43-and F-reaching 99.81 and 94.10%, respectively. The leaching concentration of heavy metals of the PG-S cured for 28 days met the requirements of the Comprehensive Wastewater Discharge Standard (GB 8978-1996). The simulation results of the geochemical model verified the feasibility of the whole immobilization process from the thermodynamic point of view. This work directly uses copper smelting slag and phosphogypsum for coupled immobilization/stabilization treatment not only to achieve the immobilization of pollutants in both solid wastes but also to obtain colloidal masses with certain compressive strength, which also provides a new option for resource utilization of phosphogypsum and copper smelting slag. This work also shows great potential in turning the actual mine backfill into cementitious material.