Shortage in phosphorus (P) resources and P wastewater pollution is considered as a serious problem worldwide. The application of modified biochar for P recovery from wastewater and reuse of recovered P as agricultural fertilizer is a preferred process. This work aims to develop a calcium and magnesium loaded biochar (Ca–Mg/biochar) application for P recovery from biogas fermentation liquid. The physico-chemical characterization, adsorption efficiency, adsorption selectivity, and postsorption availability of Ca-Mg/biochar were investigated. The synthesized Ca–Mg/biochar was rich in organic functional groups and in CaO and MgO nanoparticles. With the increase in synthesis temperature, the yield decreased, C content increased, H content decreased, N content remained the same basically, and BET surface area increased. The P adsorption of Ca–Mg/biochar could be accelerated by nano-CaO and nano-MgO particles and reached equilibrium after 360 min. The process was endothermic, spontaneous, and showed an increase in the disorder of the solid–liquid interface. Moreover, it could be fitted by the Freundlich model. The maximum P adsorption amounts were 294.22, 315.33, and 326.63 mg/g. The P adsorption selectivity of Ca–Mg/biochar could not be significantly influenced by the typical pH level of biogas fermentation liquid. The nano-CaO and nano-MgO particles of Ca–Mg/biochar could reduce the negative interaction effects of coexisting ions. The P releasing amounts of postsorption Ca–Mg/biochar were in the order of Ca–Mg/B600 > Ca–Mg/B450 > Ca–Mg/B300. Results revealed that postsorption Ca–Mg/biochar can continually release P and is more suitable for an acid environment. 相似文献
Arbuscular mycorrhizal fungi (AMF) have great potential for assisting heavy metal hyperaccumulators in the remediation of contaminated soils. However, little information is available about the community composition of AMF under natural conditions in soils contaminated by antimony (Sb). The objective of this study was to investigate the characteristics of AMF molecular diversity, and to explore the effects of Sb content and soil properties on the AMF community structure in an Sb mining area. Four Sb mine spoils and one adjacent reference area were selected from around the Xikuangshan mine in southern China. The association of AMF molecular diversity and community composition with the rhizosphere soils of the dominant plant species was studied by Polymerase Chain Reaction-Denaturing Gradient Gel Electrophoresis (PCR-DGGE). Results from all five studied sites showed that the diversity of AMF decreased with increasing Sb concentration. Principal component analysis (PCA) indicated that the AMF community structure was markedly different among these groups. Further redundancy analysis (RDA) showed that Sb contaminationwas the dominating factor influencing the AMF community structure in the Sb mine area. However, the multivariate analysis showed that, apart from the soil Sb content, extractable nitrogen content and organic matter content also attributed to AMF sequence distribution type. Some AMF sequences were only found in the highly contaminated area and these might be ideal candidates for improving phytoremediation efficiency in Sb mining regions. Gene sequencing analysis revealed that most species were affiliated with Glomus, suggesting that Glomus was the dominant AMF genus in the studied Sb mining area. 相似文献
An activation process for developing the surface and porous structure of palygorskite/carbon(PG/C) nanocomposite using ZnC l2 as activating agent was investigated. The obtained activated PG/C was characterized by X-ray diffraction(XRD), Fourier transform infrared spectroscopy(FTIR), field-emission scanning electron microscopy(SEM), and Brunauer–Emmett–Teller analysis(BET) techniques. The effects of activation conditions were examined,including activation temperature and impregnation ratio. With increased temperature and impregnation ratio, the collapse of the palygorskite crystal structure was found to accelerate and the carbon coated on the surface underwent further carbonization. XRD and SEM data confirmed that the palygorskite structure was destroyed and the carbon structure was developed during activation. The presence of the characteristic absorption peaks of C_C and C–H vibrations in the FTIR spectra suggested the occurrence of aromatization. The BET surface area improved by more than 11-fold(1201 m2/g for activated PG/C vs. 106 m2/g for PG/C) after activation, and the material appeared to be mainly microporous. The maximum adsorption capacity of methylene blue onto the activated PG/C reached 351 mg/g. The activated PG/C demonstrated better compressive strength than activated carbon without palygorskite clay. 相似文献
• Upgrade process was investigated in a full-scale landfill leachate treatment plant.• The optimization of DO can technically achieve the shift from CND to PND process.• Nitrosomonas was mainly responsible for ammonium oxidation in PND system.• An obviously enrichment of Thauera was found in the PND process.• Enhanced metabolic potentials on organics was found during the process update. Because of the low access to biodegradable organic substances used for denitrification, the partial nitrification-denitrification process has been considered as a low-cost, sustainable alternative for landfill leachate treatment. In this study, the process upgrade from conventional to partial nitrification-denitrification was comprehensively investigated in a full-scale landfill leachate treatment plant (LLTP). The partial nitrification-denitrification system was successfully achieved through the optimizing dissolved oxygen and the external carbon source, with effluent nitrogen concentrations lower than 150 mg/L. Moreover, the upgrading process facilitated the enrichment of Nitrosomonas (abundance increased from 0.4% to 3.3%), which was also evidenced by increased abundance of amoA/B/C genes carried by Nitrosomonas. Although Nitrospira (accounting for 0.1%–0.6%) was found to stably exist in the reactor tank, considerable nitrite accumulation occurred in the reactor (reaching 98.8 mg/L), indicating high-efficiency of the partial nitrification process. Moreover, the abundance of Thauera, the dominant denitrifying bacteria responsible for nitrite reduction, gradually increased from 0.60% to 5.52% during the upgrade process. This process caused great changes in the microbial community, inducing continuous succession of heterotrophic bacteria accompanied by enhanced metabolic potentials toward organic substances. The results obtained in this study advanced our understanding of the operation of a partial nitrification-denitrification system and provided a technical case for the upgrade of currently existing full-scale LLTPs. 相似文献
The adverse impacts of lead and cadmium exposure on health outcomes have been reported in the past. Few studies have been conducted on the relationship between lead and cadmium exposures and disability. We evaluated whether lead and cadmium exposures were associated with functional dependence including the total number of disabilities, activities of daily living (ADL), instrumental activities of daily living (IADL), leisure and social activities (LSA), lower extremity mobility (LEM), and general physical activities (GPA) in an elderly population. A total of 5513 eligible subjects were enrolled in the study from the National Health and Nutrition Examination Survey 2001–2006. Serum lead and cadmium exposure assessments were performed using atomic absorption spectrometry. Functional dependence was assessed by 19 structured questions. The relationships between lead and cadmium exposures and functional dependence were investigated using by multivariable linear regression models. Q2, Q3, and Q4 of lead exposure were significantly associated with the total number of disabilities, with β coefficients of ??0.62 (95% CI ??0.99, ??0.24), ??0.64 (95% CI ??1.02, ??0.26), and ??0.81 (95% CI ??1.19, ??0.42), respectively. This relationship remained significant in males. Furthermore, we analyzed the relationships between lead and cadmium exposure quartiles and various functional dependence metrics, and we determined that lead content was significantly associated with decreased ADL, LEM, and GPA (p?<?0.05) and cadmium content was inversely associated with ADL (p?<?0.05). Our study demonstrated a strong relationship between exposure to lead and cadmium and functional dependence in an elderly population.
Environmental Science and Pollution Research - Soil labile and recalcitrant carbon (C) and nitrogen (N) are strongly controlled by plant inputs and climatic conditions. However, the interrelation... 相似文献
Environmental Science and Pollution Research - The impact of soil lead (Pb) pollution on survival, growth, and reproduction of the collembolan, Folsomia candida, and Pb compartmentation in its gut... 相似文献
为了解观赏性植物对土壤重金属污染的修复效果,以开封市5种菊花(金皇后、墨菊、孔雀草、粉旭桃、玛格丽特菊)为研究对象,分析菊花以及土壤样品中镉(Cd)、铬(Cr)、铜(Cu)、铅(Pb)、锌(Zn)等5种重金属元素的含量,分析菊花对土壤重金属的富集、转移能力.采用单因子指数法、内梅罗综合指数法评价土壤环境质量,并采用模糊综合评价法进一步分析菊花带来的环境效益.结果表明,土壤中5种重金属的含量由大到小为:Zn Pb Cu Cr Cd,土壤重金属为轻度污染,且Cd对综合指数贡献最大;富集能力方面,所选菊花对5种重金属均能够富集;转移能力方面,金皇后的能力最强,其由强到弱的排序为Cr Cd Pb Zn Cu;环境效益分析,以开封菊花为例,2016—2018年开封菊花日滞尘量、日释氧量、日固碳量随着菊花的增多而增强. 相似文献