Standardization of BOD₅/COD ratio as a biological stability index for MSW

The control of biodegradable substances is the key issue in evaluating the short and long-term emission potential and environmental impact of a landfill.Aerobic and anaerobic indices, such as respirometric index (RI) and biomethane potential production (GB21), can be used in the estimation of the stability of solid waste samples.Previous studies showed different degrees of relationship between BOD₅/COD ratio compared with RI4.Aim of this study is to standardize the parameter BOD₅/COD ratio and to test the methodology under different operating conditions (dynamic or static leaching and leaching duration, 6 and 24-h) keeping constant temperature and liquid/solid ratio (L/S = 10 l/kg_TS), with the introduction of a COD fractioning method. The COD fractioning is based on the differentiation between the soluble fraction (COD_sol) and the colloidal fraction (COD_coll) using a flocculation method.The BOD₅/COD and the BOD₅/COD_sol indices are both consistent and significant and can be used as stability indices.The BOD₅/COD ratio does not seem to be influenced, for the same test duration, by the type of test, static or dynamic. In the same way the longer test duration (24-h) does not influence significantly the values of BOD₅/COD ratio. As a consequence a leaching test duration of 6-h is preferable to avoid the beginning of the hydrolysis and oxidation processes.     

混凝法处理锰矿选矿废水的试验研究

选取聚合氯化铝（PAC）、聚合硫酸铁（PFS）、聚丙烯酰胺（PAM）和六水合氯化铁（FC）4种常用混凝剂,采用正交试验,以去浊率与去锰率作为综合评价指标,探讨了不同混凝剂处理锰矿选矿废水的效果及最佳混凝条件。结果表明：在以上混凝剂中,FC的混凝效果较差;PAM对锰矿选矿废水的处理效果最优,最佳的混凝条件为：处理500 ml的废水,投加1.5 ml的PAM,pH为7.0,搅拌后沉降20 min,废水经处理后去浊率与去锰率分别为96%、92%,其中废水的pH及投药量对混凝效果的影响较大。     

Characterizing the optimal operation of photocatalytic degradation of BDE-209 by nano-sized TiO2

Brominated flame retardants have been widely used in industry. There is a rapid growing public concern for their availabilities in the environment. Advanced oxidation process (AOP) is a promising and efficient technology which may be used to remove emerging chemicals such as brominated flame retardants. This project aims at investigating optimal operational conditions for the removal of BDE-209 using nano-scaled titanium(IV) oxide. The residual PBDE congeners after photocatalytical degradation of BDE-209 by TiO₂ were analysed by gas chromatography-mass spectrometry (GC-MS). It was found that the degradability of BDE-209 by TiO₂ was attributed to its photocatalytic activity but not the small size of the particles. The half-life of removing BDE-209 by TiO₂ was 3.05 days under visible light. Tetra- and penta-BDEs were the major degraded products of BDE-209. Optimum conditions for photocatalytical degradation of BDE-209 was found to be at pH 12 (93% ± 1%), 5, 10, 20 mg/L (93.0% ± 1.70%, 91.6% ± 3.21%, 91.9% ± 0.952%, respectively), respectively of humic acid and in the form of anatase/rutile TiO₂ (82% ± 3%). Hence, the efficiency of removing BDE-209 can be maximized while being cost effective at the said operating conditions.     

Ambient volatile organic compounds at a receptor site in the Pearl River Delta region: Variations, source apportionment and effects on ozone formation

We present the continuously measurements of volatile organic compounds（VOCs） at a receptor site（Wan Qing Sha, WQS） in the Pearl River Delta（PRD） region from September to November of 2017. The average mixing ratios of total VOCs（TVOCs） was 36.3 ± 27.9 ppbv with the dominant contribution from alkanes（55.5%）, followed by aromatics（33.3%）. The diurnal variation of TVOCs showed a strong photochemical consumption during daytime,resulting in the formation of ozone（O₃）. Five VOC sources were ...     

过渡金属对Pt Rh Pd/Al2O3催化剂性能的影响

研究了过渡金属(重点考察了铜)对Pt Rh Pd／Al2O3催化剂尾气净化效能的影响,并应用XRD,TPD,TPR等手段对过渡金属在Pt Rh Pd／Al2O3催化剂中的作用机制进行了探讨．结果表明,过渡金属对Pt Rh Pd／Al2O3催化剂具有较大的改性作用,过渡金属与混合贵金属产生的协同效应有利于催化剂活性的提高．     

Sorption of radiolabelled glyphosate on biochar aged in contrasting soils

Glyphosate mobility from terrestrial to aquatic environments has raised concerns about it. Utilizing soil’s inherent properties along with sorption properties of aged biochar, we hypothesized that selective application of biochar would be more effective in economic terms for glyphosate sorption on contrasting soils. To test this hypothesis, batch experiments and liquid scintillation counting for ¹⁴ Okada, E.; Costa, J. L.; Bedmar, F. Adsorption and mobility of glyphosate in different soils under no-till and conventional tillage. Geoderma 2016, 263, 78–85.[Crossref], [Web of Science ®] , [Google Scholar]C labeled glyphosate were used. The sorption behavior of glyphosate was examined in four contrasting Australian soil types (Oxisol, Vertisol, Entisol, and Inceptisol) amended with aged biochar to determine glyphosate concentrations by measuring ¹⁴ Okada, E.; Costa, J. L.; Bedmar, F. Adsorption and mobility of glyphosate in different soils under no-till and conventional tillage. Geoderma 2016, 263, 78–85.[Crossref], [Web of Science ®] , [Google Scholar]C activity using liquid scintillation counting. Freundlich parameters were calculated for soil-soil/biochar combinations. The pattern of glyphosate sorption was Oxisol?>?Vertisol?>?Entisol?>?Inceptisol. Oxisol adsorbed approximately five times more glyphosate compared with Inceptisol. Oxisol soil system adsorbed maximum amount of glyphosate principally due to the presence of iron-aluminum oxides exhibiting variable charges which got increased due to the presence of aged biochar. Considering all the soil/soil-biochar systems, Inceptisol soil system showed the least adsorption of glyphosate. A significant contribution of char was observed only in the Entisol soil system and the finding is valuable as char can be applied in Entisol soil systems to control glyphosate mobility.     

Assessment of Pb uptake, translocation and immobilization in kenaf (Hibiscus cannabinus L.) for phytoremediation of sand tailings

The potential of kenaf (Hibiscus cannabinus L.) for phytoremediation of lead (Pb) on sand tailings was investigated.A pot experiment employing factorial design with two main effects of fertilizer and lead was conducted in a nursery using sand tailings from an ex-tin mine as the growing medium.Results showed that Pb was found in the root,stem,and seed capsule of kenaf but not in the leaf.Application of organic fertilizer promoted greater biomass yield as well as higher accumulation capacity of Pb.In Pb-spike...     

羟基磷灰石的制备及其对水中氟离子的吸附

本研究利用红外光谱(FTIR)、扫描电镜(SEM)和X射线粉末衍射(XRD)观察了共沉淀法合成羟基磷灰石(HAP)的形貌及其晶型结构,并探讨了Ca/P摩尔比、反应时间及反应温度等因素对羟基磷灰石吸附水中氟离子性能的影响。结果表明,n(Ca/P)=1.5/1、反应时间1 h、反应温度40℃、陈化时间48 h、煅烧温度200℃、煅烧时间2 h时,HAP除氟效果最佳,吸附效率和吸附容量分别达到68.8%和6.88 mg/g。实验数据Langmuir 等温模式拟合效果优于Freundlich模式,热力学参数计算可知,HAP对氟离子的吸附是自发 (ΔG0吸热 (ΔH0>0),熵增 (ΔS0 >0)的过程。HAP对氟离子的吸附符合拟二级反应动力学过程。     

外源有机酸对小飞扬草(Euphorbia thymifolia L.)修复镉污染土壤的影响

植物修复有许多优点,但当用于重金属含量较高的土壤时,通常修复效率较低。研究了添加外源柠檬酸、草酸、苹果酸对镉超积累植物小飞扬草(Euphorbia thymifolia L.)富集Cd的影响,以及3种外源有机酸对土壤pH、Cd形态及小飞扬草根系生理生化特性的影响,探讨利用有机酸强化小飞扬草修复镉污染土壤的可能性及其作用机制。结果表明,土壤Cd含量为247 mg/kg时,种植15 d后,3种有机酸均提高了小飞扬草根和地上部Cd含量,强化效果:草酸>柠檬酸>苹果酸,10 mmol/kg草酸的加入使小飞扬草地上部分Cd含量达最大值77.21 mg/kg,比对照组提高87.72%。加入有机酸使土壤pH从7.65下降至6.01~7.45,BCR三步提取法分析土壤Cd形态结果表明,酸溶态Cd含量增加,残渣态Cd含量减小。加入20 mmol/kg苹果酸降低了根系的活力和ATP酶活性,根细胞膜透性与对照组无显著性差异,而加入5、10和20 mmol/kg的柠檬酸、草酸和5、10 mmol/kg的苹果酸均显著增加了小飞扬草根系的活力和ATP酶活性,减小了根细胞膜透性。说明添加3种外源有机酸能强化小飞扬草修复Cd污染土壤,利用外源有机酸很有可能成为提高重金属污染土壤植物修复效率的有效途径。     

废旧印刷电路板差速破碎分析

为了解决废旧印刷电路板资源化过程中的粗碎问题,提出差速破碎方法;根据差速机理分析,利用自主研制双齿辊粗碎机对废旧印刷电路板基板进行差速破碎实验;最后利用Ansys APDL模块对粗碎机辊齿进行校核模拟。实验结果证明,利用差速破碎可以充分利用材料的抗拉、抗剪强度小于抗压强度的特性,能够取得良好的破碎效果,差速破碎结果呈拱形分布形式;模拟结果证明,在差速破碎过程中设备能够保持良好工作状态,可以交换2个齿辊的运转速度减小疲劳破坏。差速破碎为废旧印刷电路板资源化过程中的破碎理论提供支持,并且为废旧印刷电路板粗碎的设备选择提供参考。