Environmental assessment of garden waste management in the Municipality of Aarhus, Denmark

An environmental assessment of six scenarios for handling of garden waste in the Municipality of Aarhus (Denmark) was performed from a life cycle perspective by means of the LCA-model EASEWASTE. In the first (baseline) scenario, the current garden waste management system based on windrow composting was assessed, while in the other five scenarios alternative solutions including incineration and home composting of fractions of the garden waste were evaluated. The environmental profile (normalised to Person Equivalent, PE) of the current garden waste management in Aarhus is in the order of −6 to 8 mPE Mg⁻¹ ww for the non-toxic categories and up to 100 mPE Mg⁻¹ ww for the toxic categories. The potential impacts on non-toxic categories are much smaller than what is found for other fractions of municipal solid waste. Incineration (up to 35% of the garden waste) and home composting (up to 18% of the garden waste) seem from an environmental point of view suitable for diverting waste away from the composting facility in order to increase its capacity. In particular the incineration of woody parts of the garden waste improved the environmental profile of the garden waste management significantly.     

Mobile passive samplers: concept for a novel mode of exposure

Integrative passive sampling with devices such as semipermeable membrane devices generally relies on rigs for month-long static exposures in water. We evaluate here whether mobile exposures of passive samplers can provide reliable estimates of dissolved contaminant concentrations. Mobile exposures were obtained by towing samplers fastened to the end of a benthic trawl net. Significant and reproducible absorption of polycyclic aromatic hydrocarbons during 5 h-long deployments was made possible by high sampling rates resulting from high water turbulences during towing at 1.2-1.5 knots. Sampling rates (72-215 L d⁻¹) estimated from the dissipation of performance reference compounds were supported by in situ calibration with samplers exposed for a 30 days in the vicinity of the test site. Higher fluoranthene and pyrene absorption in samplers exposed to the trawling-induced sediment plume could be attributed to desorption from re-suspended sediments. This mode of exposure has the potential to be used in monitoring programmes.     

Dissolution of mimetite Pb5(AsO4)3Cl in low-molecular-weight organic acids and EDTA

Due to its relatively low solubility, mimetite Pb₅(AsO₄)₃Cl may control Pb and As(V) solution levels at a low value in contaminated soils. The time-dependent dissolution of mimetite by low-molecular-weight organic acids (LMWOAs) such as acetic, lactic, citric, and ethylene diamine tetra-acetic acid (EDTA) was determined. At pH 3.5, the presence of citric acid or EDTA significantly increases the solubility of mimetite while acetic or lactic acids show little effect. The effect of all organic anions on the dissolution of mimetite increased with the increase in solution pH. The rate of mimetite dissolution depended on the kind and concentration of organic solvents in the sequence r_EDTA > r_lactate > r_acetate > r_citrate. Soluble Pb and As(V) released in LMWOAs and EDTA were higher than the WHO guideline value for these elements in drinking water (10 μg As(V) L⁻¹, 10 μg Pb L⁻¹). This suggests that soil organic acids in rhizosphere can potentially liberate Pb and As(V) from mimetite in contaminated soils.     

Bromination of selected pharmaceuticals in water matrices

The bromination of five selected pharmaceuticals (metoprolol, naproxen, amoxicillin, phenacetin, and hydrochlorothiazide) was studied with these compounds individually dissolved in ultra-pure water. The apparent rate constants for the bromination reaction were determined as a function of the pH, obtaining the sequence amoxicillin > naproxen ? hydrochlorothiazide ≈ phenacetin ≈ metoprolol. A kinetic mechanism specifying the dissociation reactions and the species formed for each compound according to its pK_a value and the pH allowed the intrinsic rate constants to be determined for each elementary reaction. There was fairly good agreement between the experimental and calculated values of the apparent rate constants, confirming the goodness of the proposed reaction mechanism.In a second stage, the bromination of the selected pharmaceuticals simultaneously dissolved in three water matrices (a groundwater, a surface water from a public reservoir, and a secondary effluent from a WWTP) was investigated. The pharmaceutical elimination trend agreed with the previously determined rate constants. The influence of the main operating conditions (pH, initial bromine dose, and characteristics of the water matrix) on the degradation of the pharmaceuticals was established. An elimination concentration profile for each pharmaceutical in the water matrices was proposed based on the use of the previously evaluated apparent rate constants, and the theoretical results agreed satisfactorily with experiment. Finally, chlorination experiments performed in the presence of bromide showed that low bromide concentrations slightly accelerate the oxidation of the selected pharmaceuticals during chlorine disinfection.     

Incidence of polybrominated diphenyl ethers in central air conditioner filter dust from a new office building

This study examined polybrominated diphenyl ethers (PBDEs) in central air conditioner filter (CACF) dust from a new office building in Shenzhen, China. Human exposure to PBDE via dust inhalation and ingestion were also estimated. PBDEs level in CACF dust was lower than those in the other countries and regions. Approximately 0.671 pg/kg bw/day PM_2.5 (Particulate Matter up to 2.5 μm in size) bounded Σ₁₅PBDEs can be inhaled deep into the lungs and 4.123 pg/kg bw/day PM₁₀ (Particulate Matter up to 10 μm in size) bounded Σ₁₅PBDEs tend to be deposited in the upper parts of the respiratory system. The average total intake of Σ₁₅PBDEs via dust inhalation and ingestion for adults reached ∼141 pg/kg bw/day in this building. This value was far below the reference dose (RfD) recommended by United States Environmental Protection Agency. Human exposure to PBDEs via dust inhalation and ingestion in the new building is less than the old ones.     

粗MnSO4溶液中MnS2O6的去除条件研究

用软锰矿吸收SO2生成MnSO4时会伴随有副产物MnS2O6生成。产品中MnS2O6的存在会降低硫酸锰产品质量,同时会缓慢释放出SO2气体污染环境。本文用单因素实验方法研究了粗MnSO4溶液中MnS2O6的最优去除条件。研究结果显示,软锰矿用量为12.2 g,硫酸加入量为20 mL、反应温度100℃、反应时间3 h、搅拌速度500 r/min,MnS2O6的去除率可达91%以上。其最终产品能达到GB1622-1986一级品标准。     

钛基IrO2-SnO2电极在烟气海水脱硫恢复系统中的应用

采用浸渍-热分解法制备了含IrOx-TiO2中间层的IrO2-SnO2电极,得到的电极具有较高的析氯电催化活性和较强的稳定性,并通过电化学氧化法对Na2SO3海水脱硫模拟液进行处理,考察了电流密度、温度、pH值和电解时间等电解工艺参数对Na2SO3去除率和化学需氧量COD的影响。结果表明,在电流密度为200 mA/cm^2,pH值为3.5,电解440 mg/L的Na2SO3海水脱硫模拟液,15 min时Na2SO3去除率可达96.5%,COD去除率可达82.6%。     

催化湿式氧化预处理造纸黑液

采用连续式固定床反应器,利用自制稀土类复合金属氧化物催化剂对草浆造纸黑液进行了催化湿式氧化(CWAO)预处理研究.通过正交实验确定了最佳工艺条件为:进水COD 40 800 mg/L,空速0.8h-1,反应温度260℃,反应压力6.5 MPa.在此最佳条件下进行实验,COD去除率达90％.经CWAO工艺处理后,草浆造纸...     

巢湖低温高效聚磷菌的筛选及其特性

采用低温富集培养及混合平板分离技术,从巢湖底泥中分离筛选得到2株在低温下仍具有较高效能的菌株D3、D6,经过厌氧/好氧交替培养,2种菌株在低温下(8℃)的除磷率均达到80%以上。在低温下,研究了p H、微量元素对2株菌株生长及除磷率的影响,实验结果表明,2株菌都具有广泛的温度适应性,适宜其生长和除磷的p H为中性偏碱,微量元素的缺乏对2株菌株的生长和除磷效果有不同程度的不良影响。染色观察显示,厌氧培养时菌体内聚羟基丁酸(PHB)颗粒明显增多,转为好氧培养后异染颗粒增多,为典型的聚磷菌特征。经鉴定,2株菌均属假单胞菌属。     

活性炭涂层电极电容去离子的性能

采用活性炭涂层电极构建电容去离子吸附装置,以氯化钠模拟含盐原水,研究电压、流量、进水浓度等操作参数对活性炭涂层电极脱盐效率和能耗的影响。实验结果表明,去除率和比吸附量随着电压的增大而增加,且比能耗随之增大。流速越小,出水的浓度越低,当对出水的浓度要求较高时,宜采用小流速。当进水浓度低于活性炭涂层电极的饱和吸附量时,比吸附量随着进水浓度呈线性增加;当达到饱和吸附量时,比吸附量不会随进水浓度的增大而发生改变;比能耗随着进水浓度的增加而降低。