水热-碳酸钠法稳定化医疗废物焚烧炉飞灰中重金属的研究

研究了水热-碳酸钠法对医疗废物焚烧炉飞灰中重金属的稳定化效果及稳定化机制.结果表明,在水热条件下,碳酸钠能有效地降低飞灰中重金属的渗滤毒性,并且飞灰经水热处理后产生的废水中重金属的浓度也较低,避免了二次污染.原始飞灰中7种重金属的渗滤毒性为:Cd1.97mg/L,Cr1.56mg/L,Cu2.56mg/L,Mn17.30mg/L,Ni1.65mg/L,Pb1.56mg/L和Zn189.00mg/L,选择最佳工况对飞灰进行水热处理后(碳酸钠/干灰投加量:5/20,反应时间:8h,液固比:10/1),重金属渗滤毒性大为降低,Cd、Cr、Cu、Mn、Ni、Pb渗滤浓度均小于0.02mg/L,Zn的渗滤浓度为0.05mg/L,符合国家标准GB5085.3-2007,水热反应后废水重金属浓度均低于0.8mg/L.水热反应后飞灰重金属渗滤毒性和反应产生废水中重金属浓度均随着反应时间的延长而降低.反应时间的延长有利于硅铝酸盐的结晶与老化,使重金属在硅铝酸盐晶体中位置发生迁移,形成重金属稳定性很强的结构.重金属稳定化机制主要是由于硅铝酸盐胶体形成,结晶、老化过程中对重金属离子共沉淀与吸附作用.     

Experimental study on sediment-copper distributions in hyper-concentrated turbulent solid-liquid system

This study presents a special problem on vertical distribution for sediment and copper in hyper-concentrated turbulent solid-liquid system that is essentially different from the ordinary low-concentrated turbulent system. A resonance type turbulent simulation equipment is used for the experimental study in which a vertically uniform turbulent field of the mixture of loess and water is produced in a testing cylinder with a grille stirrer that moves up and down harmoniously with varying vibration frequencies, in order to compare the variations of the vertical profiles of sediment and copper in low- and hyper-concentratod solid-liquid system, different scenarios for input sediment content ranging from 5 to 800 kg/m^3 was considered in the experimental studies. It was found that solids copper content increases with input sediment content, So, and reaches its peak as So goes to 10 kg/m^3 and then decreases rapidly with increasing input sediment content. Such a behavior is possibly resulted from the joint effect of the specific adsorption of copper on loess, precipitation of carbonate and hydroxide of copper due to high carbonate content in the loess and the so-called ＂particulate concentration effect＂ due to the present of the sediment variation in water. The vertical sediment concentration distribution resulted from the uniform turbulence is generally uniform, but slight non-uniformity does occur as sediment concentration exceeds certain value. However, the vertical concentration distributions of soluble copper seem not to be affected much by the variation of sediment concentrations.     

Fe(II)-mediated transformation of schwertmannite associated with calcium from acid mine drainage treatment

Schwertmannite is an important Fe(III)-oxyhydroxysulfate in acid mine drainage (AMD) polluted areas and its stability depends on surrounding environmental factors and previously bound elements. The treatment and neutralization of AMD normally involve the use of lime, which leads to the discharge of abundant Ca in the mining area. Such an environmental disturbance brings up an important and less considered problem of how the reductive transformation of schwertmannite associated with coexisting Ca occurred. Here, the Fe(II)-mediated transformation of Ca-adsorbed schwertmannite and subsequent Ca repartitioning behaviors were investigated. Results showed that adsorbed Ca had a weak inhibitory effect on Fe(II)-mediated schwertmannite transformation. Release of SO₄²⁻ and SEM images both indicated that transformation rates of schwertmannite decreased under the influence of adsorbed Ca. XRD patterns indicated that adsorbed Ca altered schwertmannite transformation pathways and product compositions upon treatment with 0.4 mmol/L Fe(II). The end products of Sch notably contained both goethite and lepidocrocite; however, transformation products of SchCa only contained goethite all along. Approximately 33.5% of the surface adsorbed-Ca was released into solution within 6 hr after Fe(II) injection. Aqueous Ca behaved in a “first release and then im-mobilization” manner, which indicated dissolution and secondary mineralization drove Ca migration during the Fe(II)-mediated transformation of SchCa. Adsorbed Ca blocked the surface sites for subsequent Fe(II) adsorption, limited the Fe(II)-Fe(III) ETAE, and decreased the transformation rates. This work sheds light on the complex geochemical behavior of schwertmannite under the influences of environmental perturbations in AMD environments.     

Sorption of hazardous metals from single and multi-element solutions by saltbush biomass in batch and continuous mode: interference of calcium and magnesium in batch mode

Batch studies were performed to determine the interference of calcium (Ca) and magnesium (Mg) on the sorption of Cu(II), Cd(II), Cr(III), Cr(VI), Pb(II), and Zn(II) [from CuSO(4), K(2)Cr(2)O(7), Pb(NO(3))(2), Cr(NO(3))(3), ZnCl(2), and Cd(NO(3))(2)] by saltbush (Atriplex canescens) biomass. The results demonstrated that Ca and Mg at concentrations of at least 20 times higher than the concentration of most of the target metals did not interfere with the metal binding. The data show that the batch binding capacity from a multimetal solution at pH 5.0 was (micromol/g) about 260 for Cr(III) and Pb, and about 117, 54, and 49 for Cu, Zn, and Cd, respectively. The use of 0.1M HCl allowed the recovery of 85-100% of the bound Cu, Cr(III), and Pb, and more than 37% of the bound Cd and Zn. The column binding capacity for Pb was about 49 micromol/g from both the single and multimetal solutions, while it was, respectively about 35 and 23 micromol/g for Cr(III). The binding capacity for Cu and Zn from the single and multimetal column experiments was 35 micromol/g and less than 10 micromol/g, respectively. The stripping data from the single column experiment showed that 0.1M HCl allowed the recovery of all the bound Cu and Zn, 90% and 74% of the bound Pb and Cr(VI), respectively, and less than 25% of the bound Cd and Cr(III), while the stripping from the multimetal experiment showed that 0.1M HCl allowed the recovery of all the bound Cu and about 74%, 54%, 43%, and 40% of the bound Pb, Zn, Cd, and Cr(III), respectively.     

Alteration of shell nacre micromorphology in blue mussel Mytilus edulis after exposure to free-ionic silver and silver nanoparticles

This study describes the morphology of inner shell surface (ISS) of the blue mussel Mytilus edulis Linnaeus after short-term exposures to radiolabeled silver in free-ionic (^110mAg⁺) and engineered nanoparticulate (^110mAgNPs, <40 nm) phases. Radiolabeled silver in starting solutions was used in a similar low concentration (∼15 Bq mL⁻¹) for both treatments. After exposure experiments radiolabeled silver was leached from the ISS using HCl. It concentration for shells from both treatments was ∼0.5 Bq mL⁻¹. Whole ISS of young individuals and prismatic layer of adults showed no evidence of any major alteration process after silver uptake. However, the nacre portion of adult mussels exposed to both treatments revealed distinct doughnut shape structures (DSS) formed by calcium carbonate micrograins that covered the surface of aragonite tablets. Scanning electron microscope (SEM) imaging revealed the existence of only minor differences in DSS morphology between mussels exposed to Ag⁺ and AgNPs. From literature survey, DSS were also found in bivalves exposed to Cd²⁺. The DSS occurring in a specimen of a field-collected bivalve is also shown. Formation of distinctive DSS can be explained by a disturbance of the shell calcification mechanism. Although the occurrence of DSS is not exclusively associated with metal bioavailability to the mussels, the morphology of DSS seems to be linked to the speciation of the metal used in the uptake experiments.     

湿法烟气脱硫系统中碳酸盐含量测定方法

分析了石灰石—石膏湿法脱硫系统中碳酸盐含量的两种测定方法,并对各测定方法的优、缺点和适用范围进行了比较。     

碳酸盐对化学沉淀法回收废水中磷的影响

研究了溶液中CO_3~(2-)对磷酸铵镁(MAP)法和羟基磷酸钙(HAP)法磷回收率的影响,并对回收磷所得产物进行了傅立叶变换红外光谱和X射线衍射分析.实验结果表明:为使磷回收率达80%以上,MAP法回收磷时n(CO_3~(2-)):n(Mg~(2+))必须小于0.5,HAP法回收磷时n(CO_3~(2-)):n(Ca~(2+))必须小于0.2;溶液中的CO_3~(2-)浓度对MAP法回收产物没有明显影响,但HAP法回收磷产物中会出现大量碳酸钙.     

特殊地形地貌区燃煤电厂灰场防渗对策

结合环评实例,介绍了位于特殊地形地貌区燃煤电厂灰场的防渗对策,主要包括位于风化灰岩区、喀斯特地貌区和湿陷性黄土区灰场的防渗措施,从而为特殊地貌区灰场周边水资源保护提供借鉴。     

离子色谱法测定水中总硬度

采用离子色谱法测定水中钙、镁离子质量浓度,并以此计算水中总硬度。方法在0 mg/L~10.0 mg/L范围内线性良好,钙、镁离子的方法检出限分别为0.02 mg/L、0.003 mg/L。该方法用于测定标准混合溶液和有证标准物质,测定结果均满足质控要求。实际水样中钙、镁离子均检出,且测定结果的RSD为0.3%~1.4%,加标回收率为91.0%~103%。用该方法与国标法同时测定实际样品,结果无明显差异。     

Biogas upgrading and utilization from ICEs towards stationary molten carbonate fuel cell systems

Biogas production from anaerobic digestion has increased rapidly in the last years, in many parts of the world, mainly due to its local scale disposition and to its potential on greenhouse gases (GHG) emissions mitigation. Biogas can be used as fuel for combined heat and power systems (CHP), in particular for internal combustion engines (ICEs). In recent investigations, fuel cells have been considered as alternative CHP systems. In the present article, two different energy conversion systems are compared: a 1.4 MW class MCFC system, running on pipeline natural gas, and an in situ ICE, running on biogas. In the first case, biogas is considered as a source fuel to obtain upgraded gas to be injected in the natural gas grid. In such scenario, the location of the fuel cell power plant is no longer strictly connected to the anaerobic digester site. Several energy balances are evaluated, considering different upgrading techniques and different biogas methane/carbon dioxide ratios.