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This paper provides an introduction to groundwater PRE technology, in situ bioremediation technology, and in situ chemical oxidation technology. It also presents a summary of the core-shell structure and physical and chemical preparation methods of nZVI. Furthermore, it discusses the mechanism by which nZVI degrades heavy metals, non-metallic inorganic substances, halogenated organics, and antibiotics in groundwater through processes such as adsorption/reduction, precipitation etc. The interaction mechanism between nZVI and microorganism coupling system is described along with an analysis of the promoting and inhibiting effects that nZVI has on microorganisms. Additionally, the research progress on removing groundwater pollutants using coupling systems is discussed. Finally, the future research focus for coupling technologies is proposed. [ABSTRACT FROM AUTHOR]

This paper introduces the preparation materials and methods of hydroxyapatite, as well as the meehanism of repairing contaminated soil, and focuses on the research progress in three aspects: The remediation effect of hydroxyapatite on heavy metal contaminated soil, the improvement of soil microbial community structure and the enhancement of soil enzyme activity, and analyzes the application advantages of hydroxyapatite. The future synthesis and application direction of hydroxyapatite are proposed. [ABSTRACT FROM AUTHOR]

This paper comprehensively discusses the pathways of heavy metals into the plant root epidermis, the short-range transport pathway through the horizontal transport of coplanar and plasmodesmata, and the long-range transport pathway through the xylem and phloem for loading and unloading. The transport of heavy metal ions by the coplanar pathway is slow, while the transport of heavy metal ions by the extra plastid pathway has low resistance to migration and high rate. Cell wall adsorption and resolution are en-dogenous factors affecting the transport of heavy metal ions into the root xylem via the cytoplasmic ectodomain pathway, but the development of the Casparian strip and suberin in the root cortex, which constitute the ectodomain barrier, can block the ectodomain pathway of heavy metal ion migration to the xylem. Plant transpiration and root pressure provide the driving force for the long-distance transport of heavy metal ions in the xylem and are related to the transpiration rate of plants. The mechanism of plant detoxification and tolerance to heavy metals is mainly induced by the production of metallothionein, the formation of phytoch-elating pep tides (PCs) in stressed plants and the regionalization of heavy metals by vesicles. [ABSTRACT FROM AUTHOR]

This paper mainly reviews the methods and pros and cons of chemical reduction, ball milling and green preparation of nZVI, summarizes the modification research of nZVI composites and the application progress of heavy metal removal in recent years, and expounds the adsorption mechanism of nZVI composites for heavy metal ions, mainly adsorption, reduction, complexation, co-precipitation and synergy. The shortcomings of nZVI modified materials and heavy metal removal are pointed out, and the future research trend of nZVI removal of heavy metals is prospected, in order to provide reference for the application research of nZVI modification and removal of heavy metals. [ABSTRACT FROM AUTHOR]

The basic discuss in detail the adsorption behavior of microplastics on heavy metals and the key environmental influences in the water environment, systematically summarize the latest research progress of the composite toxic effects on various organisms by the composite pollution formed by microplastics and heavy metals, and put forward the outlook of the future related researches. The adsorption capacity of heavy metals by microplastics is related to pH, temperature, dissolved organic matter and salinity, and the composite pollution formed by the two has both synergistic and antagonistic toxic effects on aquatic organisms, plants and animals. The purpose of this paper is to provide some reference for assessing the environmental behavior and ecological risk of the composite pollutants of microplastics and heavy metals, as well as to provide some reference for future related research. [ABSTRACT FROM AUTHOR]

Many forming hypotheses of AGS, such as self-condensation hypothesis, extracellular polymer (EPS) hypothesis, nucleus induction hypothesis and selective driving pressure hypothesis, are briefly reviewed. The forming process of AGS was compared when the conditions of controlling matrix composition, coagulant, EPS, colony distribution and operating parameters were different. The application of AGS technology in domestic and industrial wastewater, such as nitrogen and phosphorus removal of wastewater, organic wastewater and heavy metal wastewater treatment, has been studied. This paper looks forward to the future development trend of this technology, with a view to providing some reference for future scholars in this field. [ABSTRACT FROM AUTHOR]

Based on the bibliometrics analysis, this paper firstly identifies that the research focus of humic acid-based material immobilization field is on immobilization remediation effect and remediation mechanism.Based on the two research focuses identified, the heavy metals in soil were classified into those in the form of cations（e.g.Cd, Pb, Hg, etc.) and those in the form of oxygen anions（e.g.As and Cr),and the immobilization effects and immobilization mechanisms of humic acid and humic acid-based materials on soil heavy metals were systematically reviewed.Humic acid and humic acid-based materials have highly effective to immobilize soil heavy metals, and their immobilization mechanisms mainly include complexation, ion exchange, electrostatic interaction, redox and co-precipitation with introduced modified materials.This review further points out the shortcomings of humic acid-based materials in immobilization remediation technology in terms of practical applications and provides an outlook on future research directions, in order to provide scientific references for in situ immobilization remediation of heavy metal contaminated soils. [ABSTRACT FROM AUTHOR]

This article reviews the research status of sewage irrigation and reclaimed water irrigation, points out the potential risk of local deterioration of the irrigation water meeting Chinese standard, and suggests that further optimization of local irrigation water.The paper summarizes the research status of purification of domestic irrigation water process and the substrate adsorption, suggests to increase and deepen the research of conventional purification processes and the development of conventional substrates, and to increase and deepen the research and development of small devices and structures, and composite and modified substrates. [ABSTRACT FROM AUTHOR]

To explore adsorption behavior of heavy metals by microplastics in water environment, this paper comprehensively analyzed the relevant public researches in recent years, including the distribution of microplastics, adsorption behavior of heavy metals by microplastics, the toxic effects of heavy metals adsorbed by microplastics on aquatic organisms, and the main influence factors of adsorption behavior.Then, the future research should focus on the response relationship between environmental factors, the surface characteristics of microplastics and the adsorption behavior of heavy metals by microplastics, and the transport process of microplastic and heavy metals in aquatic food web.It provides a theoretical basis for the study of environmental behavior and biological effects of interaction between microplastics and heavy metals in water environment. [ABSTRACT FROM AUTHOR]

The living environment of animals， plans and human beings has been seriously threatened by soil heavy metal pollution， so it’s urgently needed for cheap and efficient materials and methods to reduce their flow and migration. In this paper， soil column experiment was conducted to study the stabilization effect of hydroxyapatite（HAP)and the mixture of hydroxyapatite and fly ash （HAP+FA） on lead（Ⅱ)and cadmium(Ⅱ)in contaminated soil. It is indicated that the soil pH increased slightly with the addition of HAP and HAP+FA, and the concentration of heavy metals in the leachate was shown in this order: CK（without stabilizer） ＞ HAP+FA＞ FA. The migration of heavy metals in the soil treated with stabilizer was lower than that without stabilizer treatment. The stability efficiency of HAP was 7.5% and 2.79% higher than that of HAP+FA in lead-contaminated soil with initial concentration of 400mg/kg and 800mg/kg， respectively， and 2.5% and 0.51% higher than that of HAP+FA for cadmium-comtaminated soil with initial concentration of 400mg/kg and 800mg/kg， respectively. The stability efficiency of HAP for lead and cadmium is slightly higher than that of HAP+FA, and there was a better efficiency for the same concentration of lead of the same amount of stabilizer. [ABSTRACT FROM AUTHOR]

In order to reduce the environmental impact caused by the migration of heavy metals in electrolytic manganese residue to water, this paper added calcined dolomite sand to electrolytic manganese residue to solidified Mn2+, and analyzed the microstructure and microstructure of dolomite sand before and after calcination by XRD, BET and SEM methods. The stabilization effect of calcined dolomite sand on Mn2+ in electrolytic manganese residue at different dosage was analyzed and evaluated. The results show that with the calcination temperature increasing from 600 °C to 800 °C, the dolomite sand gradually decompositions to form alkaline oxides such as CaO and MgO. The specific surface area, pore volume and pore size of calcined dolomite sand increase continuously, which are 1.16 ~ 3.96 times, 1.7 ~ 4.18 times and 1.99 ~ 16.12 times of uncalcined dolomite sand, respectively. When 10% calcined dolomite sand at 800 °C is added to electrolytic manganese residue, the stabilization efficiency of Mn2+ is 99. 95%, and when 30% calcined dolomite sand at 700 °C is added, the stabilization efficiency of Mn2+ is 99.85%, and the concentration of Mn2+ is as low as 1.66 mg/L. The stabilization effect of calcined dolomite sand on Mn2+ in electrolytic manganese residue is mainly that Mn2+ is solidified in the form of MnO2 and MnOOH. The calcined dolomite sand at 700 * 800 °C can be used as an effective stabilizer to solidified Mn2+ in electrolytic manganese residue. [ABSTRACT FROM AUTHOR]

This paper reviews the application of silica nanomaterials in the field of heavy metals, and mainly introduces the progress and development trend of mesoporous silica nanomaterials, functional group modified silica nanomaterials and composite silica nanomaterials. Silica nanomaterials have the advantages of low cost, high specific surface, good stability and multiple modification ways, which are important development direction of heavy metal pollution control. This work also analyzes the future development trend and potential value of silicon dioxide nanomaterials, and puts forward some opinions and suggestions on the solutions to the technical problems still existing in the application of silicon dioxide nanomaterials in the field of heavy metals. [ABSTRACT FROM AUTHOR]

Plant green synthesis of nanometer zero-valent iron (FeNPs) has attracted much attention in the field of environmental remediation due to its environmentally friendly synthesis method, simple operation and excellent yield of zero-valent nanometer iron.In this paper, the mechanism (reduction, adsorption) of the removal of Cr(Ⅵ) from water by plant green synthesis of nano-iron and the influencing factors (pH value, temperature, initial concentration) in the removal process are summarized. Finally, the scientific problems existing in the removal of Cr(Ⅵ) by FeNPs are proposed and the application prospect of the green synthesis of FeNPs in environmental remediation is prospected. [ABSTRACT FROM AUTHOR]

This paper reviews the different aging processes and mechanisms of MPs by domestic and foreign scholars, and the research progress on the change of pollutant adsorption capacity before and after aging. The toxicity after aging and the release behavior of its own additives on the environment were summa・ rized・ The formation process of biofilm on the surface of MPs and the interaction between biofilm and aging MPs were revealed・ Finally, based on the current research status of MPs and their aging, it is suggested that attention should be paid to the harm of aging microplastics to the environment and the combined toxicity of aging microplastics and heavy metals to animals and higher plants in the future. [ABSTRACT FROM AUTHOR]

Isitu passivation repair technology for heavy metals is a promising processing technology. This technology mainly adds exogenous remediation agents to the contaminated soil, and undergoes a series of reactions such as adsorption, ion exchange, precipitation, oxidation-reduction and other heavy metal ions to convert heavy metals into a more stable form and fix them in the soil, thereby preventing heavy metals from passing through plant roots migrate to the upper part of the ground to achieve the purpose of repairing the soil. This paper systematically expounds the effect and repair mechanism of passivation technology, deeply analyzes the types of passivation materials, and further puts forward the problems to be solved in passivation repair technology from the practical application, and prospects for future research directions. [ABSTRACT FROM AUTHOR]

This paper summarizes the sources and water quality characteristics of wastewater with high ammonia nitrogen, and analyzes the effects of typical pollutants such as antibiotics, aromatic compounds, salinity and heavy metals on Anammox, including the changes of rritrogen removal performance, the structure of Anammox sludge (bacteria), the community structure and abundance of functional microorganisms, and the genes of microorganisms. The study of Anammox for the treatment of actual wastewater with high ammonia rdtrogen was also analyzed. The prospects were given for some problems that need to be improved in the study of the influence of typical pollutants on Anammox, in order to provide help for the application o£ Anammox in the treatment of wastewater with high ammonia nitrogen. [ABSTRACT FROM AUTHOR]

Combined with the existing research, the research progress of biochar remediation of heavy metal pollution is reviewed. This paper focuses on the mechanism of biochar immobilization of heavy metals in soil, the effect of biochar on the absorption of heavy metals by plants, the research results of the application of biochar in field engineering, and the risks and shortcomings o£ biochar as a soil improver. Finally, it is hoped that on the premise of meeting safe production, the popularization of biochar should be promoted in agricultural production, rather than limited to scientific research. Start the life cycle assessment of biochar and establish a biochar life cycle database to provide a comprehensive and effective scientific basis for the future use of biochar. [ABSTRACT FROM AUTHOR]

As an economical and effective soil remediation material, biochar can reduce the bioavailability of heavy metals through fixation and transformation of heavy metals in soil. Biochar combined with plant, animals, microorganism or other types of materials can not only improve the remediation efficiency, but also enhance the stability of the remediation effect of contaminated soil. In this paper, the effects of biochar single on soil physical and chemical properties and heavy metals were discussed, and the progress of its combination technology was reviewed, while the future development was prospected. [ABSTRACT FROM AUTHOR]

The source, treatment status and harm of incineration fly ash are briefly described, and the development status of solidification and stabilization technology is introduced. This paper mainly analyzes the effect of cement solidification method, chemical agent method, hydrothermal method and melting solidification method on heavy metals and their advantages and disadvantages, and introduce the treatment methods combining various solidification methods and other solidification treatment technologies. The existing problems of solidification and stabilization technology and the prospect of its development are described. [ABSTRACT FROM AUTHOR]

This paper reviews the production, harm and the current treatment of acid mine drainage (AMD), and mainly introduces the progress in the treatment of acid mine drainage by sulphate reducing bacteria (SRB) (anaerobic bioreactor technology, joint processing technology, microbial immobilization technology and in-situ microbial treatment technology). It is a promising method to treat acid mine drainage by sulphate reducing bacteria, with low cost, high removal rate of heavy metal ions and no secondary pollution. However, in the process of application, the low pH value of AMD makes it impossible for common microorganisms to survive. In this regard, we can domesticate SRB to make it have a lower pH tolerance value, or isolate eosinophilic aSRB, or apply biological H2S to treat AMD, so as to achieve the reuse of polluted acid wastewater while removing heavy metals. [ABSTRACT FROM AUTHOR]