Thermally enhanced bioremediation: A review of the fundamentals and applications in soil and groundwater remediation

Biochar/iron (BC/Fe) composites for soil and groundwater remediation: Synthesis, applications, and mechanisms.

Layered double hydroxides (LDHs), also referred to as anionic clay, are promising adsorbents for soil and groundwater remediation. As eco-friendly and low-cost materials, they can effectively remove/immobilize contaminants through their unique characteristics. LDHs have been extensively used in wastewater treatment. However, the application of LDHs in soil and groundwater is limited. This chapter first introduces the synthesis and characteristics of LDHs. The synthesis methods mainly include co-precipitation, urea-based method, salt-oxide method, ion exchange, and calcination. The unique characteristics of LDHs include memory effect and high anion exchange capacity. The interactions between LDHs and contaminants are then detailed, which lay the foundation of their environmental applications. LDHs can remove/immobilize anionic contaminants mainly through adsorption and intercalation, and cationic heavy metals mainly through precipitation. They can also aid the degradation of contaminants through serving as catalyst. Finally, the existing applications of LDHs in wastewater treatment serving as adsorbents and catalyst are introduced, and their potential applications in soil and groundwater is discussed. This chapter aims to give scientific researchers and industrial participators a broad view of LDHs and their applications in soil and groundwater remediation.

Nanotechnology has been widely used in many fields including in soil and groundwater remediation. Nanoremediation has emerged as an effective, rapid, and efficient technology for soil and groundwater contaminated with petroleum pollutants and heavy metals. This review provides an overview of the application of nanomaterials for environmental cleanup, such as soil and groundwater remediation. Four types of nanomaterials, namely nanoscale zero-valent iron (nZVI), carbon nanotubes (CNTs), and metallic and magnetic nanoparticles (MNPs), are presented and discussed. In addition, the potential environmental risks of the nanomaterial application in soil remediation are highlighted. Moreover, this review provides insight into the combination of nanoremediation with other remediation technologies. The study demonstrates that nZVI had been widely studied for high-efficiency environmental remediation due to its high reactivity and excellent contaminant immobilization capability. CNTs have received more attention for remediation of organic and inorganic contaminants because of their unique adsorption characteristics. Environmental remediations using metal and MNPs are also favorable due to their facile magnetic separation and unique metal-ion adsorption. The modified nZVI showed less toxicity towards soil bacteria than bare nZVI; thus, modifying or coating nZVI could reduce its ecotoxicity. The combination of nanoremediation with other remediation technology is shown to be a valuable soil remediation technique as the synergetic effects may increase the sustainability of the applied process towards green technology for soil remediation.

  Includes Illustrative Applications of Practical Design CalculationsWritten in a straightforward style and user-friendly format, Practical Design Calculations for Groundwater and Soil Remediation, Second Edition highlights the essential concepts and important aspects of major design calculations used in soil and groundwater remediation. Drawi

Conventional soil tests are commonly used to assess single soil characteristics. Thus, many different tests are needed for a full soil fertility/soil quality assessment, which is laborious and expensive. New broad-spectrum soil tests offer the potential to assess many soil characteristics quickly, but often face challenges with calibration, validation, and acceptance in practice. Here, we describe the results of a 20 year research program aimed at overcoming the aforementioned challenges. A three-step approach was applied: (1) selecting and establishing two contrasting rapid broad-spectrum soil tests, (2) relating the results of these new tests to the results of conventional soil tests for a wide variety of soils, and (3) validating the results of the new soil tests through field trials and communicating the results. We selected Near Infrared Spectroscopy (NIRS) and multi-nutrient 0.01 M CaCl2 extraction (1:10 soil to solution ratio; w/v) as broad-spectrum techniques. NIRS was extensively calibrated and validated for the physical, chemical, and biological characteristics of soil. The CaCl2 extraction technique was extensively calibrated and validated for ‘plant available’ nutrients, often in combination with the results of NIRS. The results indicate that the accuracy of NIRS determinations is high for SOM, clay, SOC, ECEC, Ca-CEC, N-total, sand, and inorganic-C (R2 ≥ 0.95) and good for pH, Mg-CEC, and S-total (R2 ≥ 0.90). The combination of the CaCl2 extraction technique and NIRS gave results that related well (R2 > 0.80) to the results of conventional soil tests for P, K, Mg, Na, Mn, Cu, Co, and pH. In conclusion, the three-step approach has revolutionized soil testing in The Netherlands. These two broad-spectrum soil tests have improved soil testing; have contributed to increased insights into the physical, chemical, and biological characteristics of soil; and have thereby led to more sustainable soil management and cropping systems.

The importance of plants to development and maintenance of soil structure, microbial communities and ecosystem functions

Chlorophenols (CPs) are a class of synthetic organic chemicals that are widely distributed in soil and groundwater, posing significant risks to human health and the environment due to persistence, acute toxicity, and potential carcinogenicity. Zero-valent iron (ZVI) has emerged as a promising remediation technique for CPs, but its efficacy is often hindered by surface passivation, non-target competition, and limited mobility in the subsurface. While CPs are inherently biodegradable, their high toxicity and the lack of functional enzymes in indigenous microbial systems restrict the effectiveness of bioremediation. Recently, a hybrid system integrating ZVI with microbial degradation draws increasingly research interests, paving out a new path for sustainable degradation of CPs. These systems leverage the synergistic interactions between ZVI and microorganisms to enhance CP biodegradation. This review provides a comprehensive analysis of the advancement. Key topics include the enhancement of electron transfer, alterations to microbial communities, mitigation of toxicity, and the interplay between other processes. Operation modes, ZVI dosage, and interactions with naturally occurring iron minerals, are also discussed in the context of applications in soil and groundwater remediation. Despite research efforts and successful implementations, critical knowledge gaps remain, particularly in regard to the characterization of microbial processes in natural systems, highlighting the need for future research.

One of the major obstacles to zerovalent iron nanoparticles (nZVI) application in soil and groundwater remediation is the limited transport, especially in low-permeability soils. In this study, direct current (constant potential of 5.0 V) was used to enhance polymer-coated nZVI mobility in different porous media, including a bed of glass beads and kaolin clay. The tests were conducted using a modified electrophoretic cell and with nZVI concentrations typical of field applications (4 g L−1). Experimental results indicate that the use of direct current can enhance the transport of the polymer-modified nanoparticles when compared with natural diffusion in low permeability or surface neutral porous medium. The applied electric field appeared to enhance the oxidation–reduction potential, creating a synergistic effect of nZVI usage with electrokinetics. Aggregation of the nanoparticles, observed near the injection point, remained unresolved.

PDF HTML阅读 XML下载 导出引用 引用提醒 中国亚热带典型天然次生林土壤微生物碳源代谢功能影响因素 DOI: 10.5846/stxb201102230204 作者: 作者单位: 中国科学院生态环境研究中心 城市与区域生态国家重点实验室,中国科学院生态环境研究中心 城市与区域生态国家重点实验室,中国科学院生态环境研究中心 城市与区域生态国家重点实验室,中国科学院生态环境研究中心 城市与区域生态国家重点实验室,中国科学院生态环境研究中心 城市与区域生态国家重点实验室,中国科学院生态环境研究中心 城市与区域生态国家重点实验室,中国科学院生态环境研究中心 城市与区域生态国家重点实验室 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金资助项目(40871130); 国家重大基础研究资助项目(2009CB421105); 城市与区域生态国家重点实验室专项基金资助项目 Relationships between carbon source utilization of soil microbial communities and environmental factors in natural secondary forest in subtropical area, China Author: Affiliation: Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences,,,,,, Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:天然次生林地比人工林地不仅土壤肥力较高,且土壤碳代谢功能更强。然而维持天然次生林高碳代谢功能的原因尚不十分清楚。分析天然次生林中土壤微生物碳源代谢功能的影响因素对于调控土壤微生物的功能乃至天然次生林的保护具有重要意义。选择中国亚热带地区典型天然次生林,研究了土壤微生物碳源代谢功能与土壤化学和物理因素及植物因素的关系。结果表明,3类因素能显著解释土壤微生物碳源代谢功能54.4% 的变异。乔木层植物多样性、土壤碳氮比、pH值和含水量是导致天然次生林碳代谢功能差异的主要因素,分别显著解释了土壤微生物碳源代谢16.7%、12.4%、10.5%和10.5%的变异。天然次生林较低的土壤碳氮比、较高的土壤含水量和土壤pH值(酸性范围内),有利于土壤微生物碳源代谢功能的提高,同时天然次生林较高的阔叶树种的比例也能增加土壤微生物碳源代谢功能。 Abstract:Compared with artificial plantation, natural secondary forest has higher function of nutrient cycling, especially carbon source metabolism function. However the reasons for higher nutrient cycling function in natural secondary forest are still not clear. To understand the nutrient cycling function of natural secondary forest, we analyzed the relationship between carbon source metabolism properties of soil microbial communities and the environmental factors in subtropical area, China. From 40 sample plots 40 soil samples at 0-10 cm depth were sampled. The carbon source metabolism capacity of soil microbial communities was analyzed using Biolog method. The soil properties and plant composition of the plots were also surveyed.Variance partitioning showed that three groups of factors significantly explained 54.4% variation of carbon source utilization by soil microbial communities. Among them, soil chemical characteristics and vegetation factors explained 13.0% (P = 0.001) and 13.4% (P = 0.001) variation, respectively. There existed interaction among three groups of factors. The interaction between soil chemical and physical characteristics explained 13.8% variation, the interaction between vegetation and soil physical characteristics explained 12.9% variation and the interaction of soil chemical factors and vegetation factors explained 1.5% variation of carbon source utilization.Redundancy analysis (RDA) was used to analyze relationship between carbon source utilization ability and vegetation factors, soil physical characteristics and chemical characteristics respectively. Monte Carlo permutation test (n=999) was used to preselect factors that significantly influenced carbon source utilization of soil microorganisms. RDA showed that among the 7 vegetation factors, tree layer species richness, root biomass and tree biomass significantly influenced carbon source utilization ability of soil microbial communities, which explained 16.7% (P = 0.001), 6.3% (P = 0.017) and 4.6% (P = 0.046) variation of carbon source utilization, respectively. The soil physical characteristics, including soil moisture content, sand content and soil bulk density, also significantly influenced carbon source utilization of soil microbial communities, which explained 10.5% (P = 0.003), 8.8% (P =0.01) and 7.2% variation (P = 0.005) of carbon source utilization. As for the 6 soil chemical characteristics, only soil pH, C∶N ratio and available nitrogen content significantly explained the variation of carbon source utilization by soil microbial communities, which explained 10.5% (P = 0.006), 12.4% (P = 0.002) and 5.2% (P = 0.047) variation of carbon source utilization.According to the explained variation of carbon source utilization by soil microbial communities, the lower C∶N ratio in soil, higher soil moisture content and soil pH (within the scope of acid soil) were the main factors improving soil carbon source metabolism capacity in natural secondary forest. The higher broad-leafed species ratio also benefit soil carbon source metabolism capacity in natural secondary forest. 参考文献 相似文献 引证文献

Remediation of soil and groundwater contaminated with toxic metals has been a major environmental challenge for decades. Yet, cost-effective and sustainable in situ remediation technologies remain lacking. Over the last 15 years or so, an innovative in situ remediation strategy has shown promising by means of stabilized nanoparticles. Stabilized nanoparticles are prepared using novel stabilizers that facilitate the deliverability and transport of nanoparticles in the subsurface. This study reviews synthesis and characterization of some model stabilized nanoparticles and their application for remediation of metal-contaminated soil and water. Fate and transport of these stabilized nanoparticles in groundwater and soil are also examined. Lastly, this review identifies the key knowledge gaps such as lack of field data pertaining to the long-term effectiveness of the immobilized metals and impacts of the delivered nanoparticles on the biogeochemical conditions in the subsurface. The information may facilitate further development of this promising remediation technology.

Studies on effects of nitrogen deposition were mainly focused on temperate grasslands in Inner Mongolia of China. In addition, there are substantial differences between the present simulation methods and the natural nitrogen deposition. A three-year experiment was carried out to compare the effects of simulation methods (common urea and slow-released urea) and nitrogen deposition rates (0, 25, 50, 75, 100, 150, 200 and 300 kg N·hm-2·a-1) on soil nutrients and biological characteristics in Hulun Buir Grassland. We found that simulated nitrogen deposition had significant influences on soil chemical properties, biological properties and enzyme activities. With the increases of nitrogen deposition, soil pH declined with the greatest extent of 0.2 units, while the highest concentrations of total dissolved nitrogen (TDN) and dissolved organic carbon (DOC) increased by 5-7 times and 12%-36%, respectively. There was a decline trend for soil total phosphorus (TP) and organic phosphorus (TOP). Microbial biomass and metabolic activity increased firstly and then decreased. Moderate simulated nitrogen deposition rates significantly increased soil carbon, nitrogen and phosphorus related enzyme activities. Compared to common urea, using slow-released urea to simulate nitrogen deposition decelerate the decline of soil pH and the increase of dissolved nutrients, and smoothed the change of microbial biomass, metabolic activity, and nitrogen hydrolyzed enzyme activities. Overall, the results confirmed that continuous nitrogen input caused the decline of soil pH and the increase of bioavailable carbon and nitrogen, and then changed microbial biomass and activity.

Contrasted effects of annual and perennial grasses on soil chemical and biological characteristics of a grazed Sudanian savanna

The European Commission (EC) has recognized a need for strengthening innovation of environmental technologies in order to increase competitiveness of European technologies on a global market and to achieve a more sustainable development in Europe. In the area of soil and groundwater remediation, innovative technologies are principally available and have proven applicability and performance on demonstration scales, but market uptake is disappointing. Consequently, initiatives have been launched in order to promote application of these technologies and to investigate on the harmonization of applications. The European Co-ordination Action for Demonstration of Efficient Soil and Groundwater Remediation (EURODEMO), an EC-funded project, is one strategic initiative for supporting these goals. This article summarizes results obtained so far regarding the investigation of the European situation and some undertaken and envisaged measures to achieve better market uptake. The results of this research project may serve as prerequisites for a European Environmental Technologies Verification (ETV) process. © 2006 Wiley Periodicals, Inc.

Surfactants are crucial for reducing surface tension at liquid interfaces and have diverse applications in various fields. Solutions of surfactants can help remediate contaminated soil and groundwater. Foams, dispersions of gas bubbles within a liquid stabilized by surfactants, exhibit enhanced sweep properties that can improve the cleaning efficiency in groundwater remediation. However, surfactant-stabilized foams are thermodynamically unstable, and this poses challenges to their applications. Utilizing nanoparticles in conjunction with surfactants has shown promise in enhancing foam properties and contaminant recovery. Biosurfactants, which are surfactants naturally produced by microorganisms, offer a promising alternative to synthetic surfactants due to their biodegradability and low toxicity. In this paper, we investigated the use of biosurfactants, specifically rhamnolipids, in combination with bio-nanocrystals, namely cellulose nanocrystals (CNCs), to improve foaming properties and assess contamination recovery through foam flooding tests. The effect of pH and CNCs on the foaming properties of the rhamnolipid solution was also examined. Foam stability and foamability were evaluated using modified bulk foam tests, considering foam stability parameters and maximum foam volume. Constant shear rate and strain amplitude sweep tests were performed on different foams formulated at varying pH levels to assess viscosity and elasticity, and to distinguish the foam exhibiting superior properties. Furthermore, sand pack flooding experiments were conducted to assess the performance of rhamnolipid-stabilized foams in groundwater remediation. The results reveal pH-dependent variations in the foaming properties of the mixture. The findings suggest that an optimal, eco-friendly foam with maximum stability, foamability, and elasticity can be formulated by using 1000 mg/L rhamnolipid together with 1000 mg/L CNCs at a pH value of 10. Additionally, experiments demonstrate that foams with optimal properties can recover approximately 70% of contaminants (n-decane), representing more than three times the recovery achievable through the same amount of water injection.

new edition has updates throughout the text, and it presents all new material on air sparging, dual phase extraction, chemical oxidation, and vacuum pumps, as well as several new practical examples. It illustrates the engineering calculations needed during site assessment and remedial investigations. It also shows readers how to estimate the rates of groundwater movement and plume migration. This book provides important design calculations for vadose zone soil remediation as well as groundwater remediation--