电解预处理-UASB-CASS工艺处理糠醛废水

对电解预处理-UASB-CASS工艺处理糠醛废水进行了研究,通过试验确定了电解预处理阶段主要影响因素为电流强度大小和电解时间,极板间距对COD去除率影响不大;电解预处理最佳工艺参数为:电流强度0.3 A,电解时间4 h,极板间距30 mm.在此条件下COD去除率为20.6%,废水可生化性提高了38.1%.加上后续的UASB-CASS工艺,出水COD浓度＜150 mg/L,满足《污水综合排放标准》(GB8978-1996)二级排放标准.     

Bridging the gap between laboratory experiments and naturally occurring markets: An inferred valuation method

Several recent studies have found important differences between behavior in the laboratory and the field. We explore two possible causes for the divergence: social concerns and unfamiliarity with the traded good. Consistent with our conceptual model, we find that people overstated their preferences for relatively familiar goods with normative attributes and understated their preferences for a relatively unfamiliar good with low normative motivations in the laboratory as compared to the field. We also find that for goods with a normative dimension, a new method we refer to as inferred valuation has the potential to narrow the lab–field gap. In some cases, willingness-to-pay obtained from a conventional valuation elicitation method is more than twice the value from the new inferred valuation approach.     

Adsorption distribution impact on preferential transport within horizontal flow constructed wetland (HFCW)

Predicting preferential water flow and solute transport in soils is in the interest of scientists and engineers in the fields of agricultural soil, forest hydrology, soil physics and wastewater treatment by constructed wetland. In artificial wetlands, any preferential pathway induces an insufficient residence time of pollutants in the soil, making an incomplete and unfinished biodegradation process, a wrong evaluation of the hydraulic residence time of the system which would hinder its management in a complete system with several entities of treatment and a non-homogeneous growth of the biofilm in the solid filter mass. This paper is a contribution in tracer experiment data analysis within a horizontal flow constructed wetland built in a storm water basin. A two-dimensional numerical model was used to simulate flow and reactive solute transport. The flow model was successfully calibrated in very dry soil conditions. The adsorption profiles used in the reactive transport modeling are those of five molecules: metolachlor, atrazine, deethylatrazine (DEA), deisopropylatrazine (DIA), and hydroxyatrazine (HA). We show that the adsorption distribution is an internal factor of soil which is responsible to the “preferential” pathway transport in a homogeneous gravel texture. The mean residence time of pollutants within the filter is strongly correlated with the average value of the adsorption coefficient. Moreover, we note a lack of significant impact of the heterogeneity of the medium on the statistical moments of breakthrough curve. It appears that a uni-modal breakthrough curve is not significant to the absence of preferential flow in the medium and at least a two-dimensional display can provide sufficient evidence on the presence or absence of preferential pathways. Finally, using a PLS regression, it is possible to perfectly discriminate the number of peaks of concentration and the asymmetry of the breakthrough curve.     

Buying Time: Real and Hypothetical Offers

This article provides the results of a field test of contingent valuation estimates within a willingness to accept framework. Using dichotomous choice questions in telephone–mail–telephone interviews, we compare survey respondents' responses to real and hypothetical offers for the opportunity to spend time in a second set of interviews on an undisclosed topic. Five hundred and forty people were randomly split between the real and hypothetical treatments. Our findings indicate no significant differences between people's choices with real and hypothetical offers. Choice models werenotsignificantly different between real and hypothetical offers.     

Temperature calibration formula for activated charcoal radon collectors

Radon adsorption by activated charcoal collectors such as PicoRad radon detectors is known to be largely affected by temperature and relative humidity. Quantitative models are, however, still needed for accurate radon estimation in a variable environment. Here we introduce a temperature calibration formula based on the gas adsorption theory to evaluate the radon concentration in air from the average temperature, collection time, and liquid scintillation count rate. On the basis of calibration experiments done by using the 25 m³ radon chamber available at the National Institute of Radiological Sciences in Japan, we found that the radon adsorption efficiency may vary up to a factor of two for temperatures typical of indoor conditions. We expect our results to be useful for establishing standardized protocols for optimized radon assessment in dwellings and workplaces.     

基于潜在分类模型的农田生态补偿标准测算——一个离散选择实验模型的实证

确立科学合理的生态标准是建立和提高社会主义生态文明的关键。本文对当前我国运用选择实验法对农田生态补偿标准估算多假设受访者同质性偏好的现状,运用潜在分类模型(Latent Class Model,LCM)研究武汉市不同类别特征的市民对农田生态服务价值的保有意愿情况,并进一步运用Gold Latent软件测算基于市民支付意愿的武汉市农田生态补偿标准。研究发现:193.5%的武汉市受访市民愿意为保有和改善农田生态系统的服务功能进行一定额度的农田生态补偿标准支付,但仍有部分比例的受访者对农田生态服务价值的全面认知还不够(如空气质量)。2武汉市不同受访市民对农田生态属性的偏好存在异质性,93%的受访市民属于正常偏好型。另有7%的受访市民属于空气质量偏好型。受访者的收入水平、对农田生态服务价值的意识程度和是否愿意进行一定额度的农田生态补偿支付三个变量是影响其类别归属的决定性因素。3正常偏好型和空气质量偏好型市民对于农田生态补偿的支付意愿分别为6 888.74元/hm~2和518.50元/hm~2,计算得到基于武汉市市民平均支付意愿的农田生态补偿标准为7 407.24元/hm~2。研究结果不仅可以为武汉市农田保护制定出更具针对性和合理的农田生态补偿标准提供初步的科学依据,还可以为农田生态补偿筹集到除了中央政府财政转移之外的来自于农田生态服务受益者的资金支付。     

基于消费者对产地信息属性偏好的可追溯猪肉供给侧改革研究

基于目前市场上可追溯食品品种单一且存在明显结构性失调的现实特征,本文以可追溯猪肉为案例,运用真实选择实验与Logit模型相结合的研究方法,在对可追溯猪肉设置可追溯信息、可追溯信息真实性认证与价格属性的基础上,将产地信息属性纳入可追溯信息属性体系,研究消费者对产地标签的认知与产地属性支付意愿,以及影响消费者对加贴产地标签的可追溯猪肉购买选择的主要因素。研究发现,在构成可追溯猪肉的不同类别的信息属性及其层次中,消费者对可追溯信息真实性政府认证属性的支付意愿最高,其次是对高层次可追溯信息属性的支付意愿,而且相对于外地产标签信息属性,消费者更偏好于具有本地产标签的可追溯猪肉。同时消费者对产地标签的认知与家庭收入状况,显著影响其对加贴产地信息属性标签的可追溯猪肉的购买选择。本文研究的政策含义是,现有可追溯猪肉所包含的安全信息属性残缺不全,并不具备事前预警功能,品种存在着明显的结构性失调,应从供给侧结构性改革的角度,鼓励生产者生产多信息属性的多品种可追溯猪肉,同时充分发挥市场的决定性作用,丰富市场以满足不同的消费需求;与普通猪肉相比较,可追溯猪肉的市场价格上扬,可通过实施精准减税等政策引导可追溯猪肉的生产,以降低可追溯猪肉的市场价格,扩大可追溯猪肉的市场容量;在稳定生猪养殖等支持政策的同时,逐步推行产地政策,为生产者和消费者建立信任关系,提供猪肉安全信息甄别机制。     

2种组合工艺处理靛蓝废水的中试实验研究

分别采用水解酸化/好氧MBBR/BAF和水解酸化/好氧MBBR/臭氧氧化/BAF 2种组合工艺对实际靛蓝废水进行处理规模为24 m3/d的中试研究。实验结果表明,当进水COD平均初始浓度为2 100 mg/L、平均色度为90倍、系统总水力停留时间为40 h时,前一种组合工艺对COD和色度的去除率分别达93.27%和89.87%;而后一种组合工艺对COD和色度的去除率分别达97.96%和100%,工艺中臭氧氧化单元可使处理后出水中有机物的数量大大降低。表明水解酸化/好氧MBBR/臭氧氧化/BAF组合工艺处理靛蓝废水更为有效,但增加臭氧氧化单元会使每吨废水处理成本增加0.55元。     

轻质非水相流体(柴油)在多孔介质中的垂向运移

紫外分光光度计为测量手段,通过简易一维土柱实验装置模拟了在不同条件下柴油在多孔介质中的运移。实验发现:柴油在两种不同粒径的砂土中垂向迁移的规律大致相同,并在持续淋滤108 h后,约90%的残余柴油都聚集在距离表层30 cm的范围内;间歇淋滤比持续淋滤更容易使柴油聚集在毛细带,不易向深处迁移;并在一定程度上验证了LNAPLs在地下环境中运动的渗漏、顶托阶段。     

超细颗粒物凝聚中试试验均匀给料方案研究

给料的均匀性对PM2.5团聚试验至关重要,运用数值方法,采用LES模型计算湍流流场,采用DPM模型计算颗粒运动轨迹,分析PM2.5团聚中试试验台烟道内加设钝体后颗粒的均匀分布,得到了水平烟道各截面处颗粒浓度分布及数值的均方差曲线,发现在试验台圆方管处加设钝体,能有效改善烟道内煤灰颗粒的均匀分布。