Predicting the Concentration of Total Mercury in Mineral Horizons of Forest Soils Varying in Organic Matter and Mineral Fine Fraction Content

In this study, an artificial neural networks (ANN) model was developed to predict the removal of a polycyclic aromatic hydrocarbon (PAH), namely, naphthalene from marine oily wastewater by using UV irradiation. The removal rate was used as model output and simulated as a function of five independent input variables, including fluence rate, salinity, temperature, initial concentration and reaction time. The configuration of the ANN model was optimized as a three-layer feed-forward Levenberg–Marquardt backpropagation network with log-sigmoid and linear transfer functions at the hidden (12 hidden neurons) and output layers, respectively. By considering goodness-of-fit and cross validated predictability, the ANN model was trained to provide good overall agreement with experimental results with a slope of 0.97 and a correlation of determination (R ²) of 0.943. Sensitivity analysis revealed that fluence rate and temperature were the most influential variables, followed by reaction time, salinity and initial concentration. The findings of this study showed that neural network modeling could effectively predict the behavior of the photo-induced PAH degradation process.     

An Observational Method for the Assessment of Biogas Production from an Anaerobic Waste Stabilisation Pond treating Farm Dairy Wastewater

A biogas production assessment method based on the visual monitoring of biogas evolution events in an anaerobic waste stabilisation pond was developed and applied to an anaerobic pond treating farm dairy wastewater in New Zealand. Major biogas-induced perturbations at the pond surface were classified as either type 1 or 2 events and other observed biogas activities as small bubble events. Mean counts of types 1 and 2 events varied from 7·3 to 30·0 per hour and 4·3–34·0 per hour, respectively, over the pond surface and the frequency of events decreased as both organic loading and temperature increased. Preliminary estimates of areal gas production rates, obtained using the observational method, ranged from 0·002 to 0·015 m³ m⁻² day⁻¹ for major eruptions and 0·0004–0·024 m³ m⁻² day⁻¹ for small bubble events, giving a total range of 0·002–0·039 m³ m⁻² day⁻¹. Pond temperatures at 2·75 m depth showed relatively minor fluctuations on a diurnal basis and ranged between 13 and 15°C from days 1–60, reaching a maximum of 24°C at day 190. Refinements proposed for future method development include an increased number and range of event categories, the automatic recording of events and the use of an improved cover. Further work is required to assess the general applicability of the method to anaerobic ponds.     

Application of stabilization pond for purification of textile wastewater in Esfahan,Iran

Two experimental ponds, with an effective volume of 2 m3 each, were constructed in a workshop at the textile plants to investigate the potential for a stabilization pond for purification of textile wastewater. Parametric analysis of pH, temperature, turbidity suspended solids, total suspended solids, DO, BOD, COD, N, and algae was carried out on the influent and the effluent according to the procedures recommended by the standard methods (APHA, 1971). Considering the results obtained from tests after daily observations, the application of an oxidation pond for treatment of textile wastewaters in the winter time was not promising. The ponds had a little activity in aerobic condition. In other seasons the ponds were efficient and the removal of BOD, COD, and N was 81, 78, 72% respectively, with a loading rate of 7.950 g BOD m^?2 day^?1 and detention time of 20 days. The ponds were usually saturated and sometimes super-saturated with dissolved O₂. The experimental ponds were put to work in series for BOD, COD, and N removal observation. The removal did not improve compared with a single pond and algae concentration was noticeably reduced in the effluent.     

Impact of Prior Physico-Chemical Treatment on the Clogging Process of Subsurface Flow Constructed Wetlands: Model-Based Evaluation

The objective of this study was to check the effect of the use of a physico-chemical treatment on the clogging process of horizontal subsurface flow constructed wetlands by means of dynamic modelling. The hydraulic submodel was based on series as well as parallel branched complete stirred tanks of equal volume. The model was validated with data obtained from 2 identical experimental wetlands, which had a surface area of 0.54 m² and a water depth of 0.30 m, and that were monitored over a period of 5 months. One of the wetlands was fed with settled urban wastewater, whereas the other with the same wastewater, but previously treated with a physico-chemical treatment. In the model, pore volume reduction depends on the growth of bacteria and on solids retained. The effluent concentrations of COD and ammonium in both experimental wetlands were very similar in all the conditions tested, and therefore the physico-chemical treatment did not improve the removal efficiency. The model indicated that after 120 days of operation in some regions of the wetland fed with settled wastewater the porosity decreased in a 17%, whereas in the other wetlands it only decreased as much as 6%. The use of a prior physico-chemical treatment is a good alternative for avoiding an anticipated clogging of subsurface flow constructed wetlands.     

大薸对奶牛场废水中耐药基因的去除效果和驱动因子分析

为探究大薸对奶牛场废水的净化效果,该研究选用温室模拟培养结合高通量测序方法,研究大薸对奶牛场废水中耐药基因（Antibiotic Resistance Genes,ARGs）的去除效果及驱动因子。结果显示：对于奶牛场3种实际废水（原水、厌氧池和氧化塘废水）,大薸整体呈现良好的净化效果,废水中大部分ARGs的绝对丰度呈现正去除效果,在原水、氧化塘废水和低浓度厌氧池废水中,大薸处理后ARGs绝对丰度（lg值）分别下降0.25（ermA 和fexA）～3.66（blaOXA-1）、0.08（blaTEM-1）～3.51（strB）和0.09（fexA）～4.07（strB）,而对高浓度厌氧池废水,则仅有9/16的ARGs呈现正去除。经过大薸处理后,不同废水中的微生物多样性和丰度均升高,废水中优势菌种Proteobacteria和Firmicutes相对丰度下降,而Bacteroidetes 和Actinobacteriota相对丰度上升,相较于无植物处理组中微生物群落差异较大。RDA分析结果表明,优势菌属（Hydrogenophaga、Flavobacterium、Bacillus和Gemmobacter）结合环境因子对ARGs变化的解释率分别为77.67%和78.57%,网络分析结果亦表明,ARGs变化与微生物和环境因子密切相关。因此,大薸对ARGs的去除是通过微生物变化和环境因子改变等多种作用共同驱动的。研究结果可为畜禽污水中ARGs污染防控提供理论依据,有助于推动植物生态处理技术的绿色可持续发展。     

Temperature variations in unfrozen soils with variable hydrothermal properties

A comprehensive understanding of the hydrothermal properties of soil is required to model heat distribution in unsaturated soils. In this study, we aim to model heat distribution throughout the profile of unfrozen soil while its thermal diffusivity varies with time and depth. The proposed model is based on the fundamental solution of the one‐dimensional transient heat conduction equation using the decomposition method. We calibrate our model using experimental data from soils of different textures in the literature. The new model can estimate soil thermal diffusivity at different depths and times and uses easily accessible characteristics such as the degree of saturation and the texture of the soil. In this study, the performance of the new model is compared to the performance of the simplified model in which constant thermal diffusivity is considered throughout the profile. Moreover, the model is validated by comparing it with in‐situ temperature measurements within depth of soil profiles with different textures. The results show a very good agreement between the predicted and the measured temperature throughout the soil profiles. Such a validation shows that with increasing degree of soil saturation, depletions in temperature for fine‐textured soils are more significant than those for coarse‐textured soils. Finally, the new model is applied to a double‐layer soil in the Alsace region to define temperature variation in the profile of soil with different characteristics in each layer. For a double‐layer profile, the continuity of the temperature as well as the heat flux is verified at the interface between the two layers.     

猪场废水灌溉对潮土硝态氮含量变化的影响

该文应用猪场废水处理工艺中3个阶段的出水（原水—猪圈舍干清粪后冲洗直接流入积水池的水;厌氧水—原水经厌氧池处理后的出水;仿生态塘水—经曝气和植物吸收处理的厌氧水）与地下水1︰5（体积比）配比和厌氧水不同灌溉量进行冬小麦小区灌溉试验,通过监测土壤硝态氮含量动态变化和残留量筛选适宜的混合水类型和厌氧水灌溉量,为制定合理的猪场废水灌溉制度提供理论依据。试验结果表明：应用3种混合水灌溉0～100 cm土壤剖面硝态氮含量随深度增加呈现“S”形变化趋势,小麦收获后各层土壤硝态氮含量均比初始值有所增加;收获后3种混合水灌溉处理0～100 cm土层中的硝态氮累积量比拔节期均有很大增加,仿生态塘水︰地下水1︰5处理变化幅度最小,较适宜灌溉;厌氧水灌溉量与土壤中硝态氮淋溶量和残留量成正相关关系,中灌水量（500 m3/hm2）较适宜。灌浆期灌水大大增加了收获后土壤中的硝态氮含量,灌浆期宜使用地下水灌溉。     

Effect of Temperature on Bio-Kinetic Coefficients in UASB Treatment of Municipal Wastewater

Upflow anaerobic sludge blanket (UASB)reactors were used to treat municipal wastewater attemperatures of 6, 11, 15, 20 and 32 °C and athydraulic retention times (HRTs) ranging from 48 to 3 h overan operational period of approximately 860 days. The Monodmodel was used to evaluate substrate utilization. TheArrhenius model was used to calculate the activationenergies from which temperature coefficients weredetermined. It was found that the maximum specific substrateutilization rate constant (k) decreased from 0.387 d^-1(at 32 °C) to 0.041 d^-1 (at 6 °C). Thedecay rate constant (k_d), yield coefficient (Y_g),half velocity constant (K_s) and maximum specific growthrate (μ_m ) were also impacted by temperature in theUASB treatment of municipal wastewater.     

猪场废水灌溉对潮土磷素肥力的影响

在北方缺水地区利用猪场废水对冬小麦进行小区灌溉试验,分析不同水质及水量灌溉处理土壤剖面全磷和速效磷的时空分布特征.结果表明:不同水质灌溉处理土壤全磷和速效磷在土层中的分布特征相似,均随深度增加含量逐渐减少;厌氧水不同灌溉量处理土壤全磷和速效磷含量与灌水量呈正比关系;收获后,各处理土壤耕层(0-40cm)磷素累积量均有所增加,磷素活化系数明显增大,大部分在7%～9%之间,高量厌氧水灌溉处理达到10.4%.采用未经处理的猪场废水多次灌溉后,过量磷素向下层土壤淋溶现象明显;高量厌氧水灌溉土壤耕层累积大量速效磷,易随地表径流污染周围水体.这两种类型的猪场废水不适于作为磷源进行农田灌溉.     

污泥厌氧消化过程的流变规律与脱水性能

为阐明厌氧消化过程中污泥流变学与污泥理化性能(脱水性能)之间的关联及低温水解预处理对污泥厌氧消化产气的影响,对常规污泥及低温热水解预处理污泥进行厌氧消化试验,结果表明试验结束时,低温热水解-厌氧消化的挥发性固体(volatile solids, VS)去除水平较常规厌氧消化污泥提高3.7个百分点,低温热水解预处理也使得消化污泥的脱水性提高1.59%;污泥屈服应力分别了降低了64.51%和71.47%;稠度系数分别减小了90.94%和92.83%,污泥流动性增强。整个消化过程VS/总固体(totalsolids,TS)和屈服应力随时间的变化均呈对数下降趋势;通过线性方程拟合和皮尔逊相关性分析表明,屈服应力与VS/TS、屈服应力变化与脱水性能改善两两间的拟合优度(R^2)均大于0.94,表明在厌氧消化过程中屈服应力、屈服应力变化与污泥VS/TS、脱水性能具有较好的线性关系。研究结果从流变学角度为厌氧消化过程中的监控和优化提供新思路和理论依据。     

A practical formula for quantifying the thermal conductivity of Tottori dune sand

Abstract

Sustainable agriculture needs appropriate management of water, chemicals and heat in soil. In this study, we focused on thermal conductivity, which is among the various soil physical properties that are crucial for the sustainable management of agricultural fields. To expand the Mochizuki model, which describes thermal conductivity as a function of water content and solution concentration, we considered the water content, solution concentration and temperature as independent variables. The thermal conductivity of Tottori dune sand was measured under conditions of various combinations of these three independent variables. We observed that the thermal conductivity increased linearly with increasing water content, 0.054–0.276 m³ m^?3, for fixed temperature and solution concentration, and varied linearly with solution concentration for fixed temperature and water content. These results are consistent with the Mochizuki model. Using the Mochizuki model, the experimental parameters, which are dependent variables of water content and solution concentration, are shown as functions of water content. From regression analyses of the relationships between the experimental parameters and temperature, we expanded the Mochizuki model into a new practical formula that quantifies the soil thermal conductivity as a function of water content, solution concentration and temperature.     

基于改进秸秆床发酵系统的厌氧发酵产沼气特性

为同时解决农业秸秆和分散式畜禽养殖废水的资源化问题,以打捆秸秆为固定相,以猪粪废水为流动相,构筑秸秆床厌氧反应器,并在反应器后部连接废水二级厌氧反应器,研究秸秆床发酵系统的产气特性及可行性。结果表明:秸秆床发酵系统可同时处理打捆秸秆和猪粪废水,且不影响各发酵原料的厌氧生物转化率,秸秆床发酵系统中秸秆干物质产气量为394.96 mL/g,略高于秸秆单独发酵(382.11 mL/g);秸秆床发酵系统产气稳定性大幅提高,避免了单一发酵原料日产气量波动较大的问题,对产气中平均甲烷体积分数影响明显,秸秆床发酵系统、纯猪粪废水和纯秸秆发酵产气中平均甲烷体积分数分别为57.40%、60.37%和47.32%;与各物料单独发酵相比,秸秆床发酵系统平均容积产气率大幅提高,纯秸秆和猪粪废水单独发酵容积产气率仅为秸秆床发酵系统的69.42%和66.94%;试验35 d后,秸秆机械强度和孔隙度明显降低,秸秆互相粘结导气性下降,造成秸秆上浮严重及进水短流,反应器出水化学需氧量浓度快速增加并稳定在较高浓度,故在秸秆床反应器后部必须连接废水二级厌氧反应器以进一步处理秸秆床反应器出水。综合以上结果,采用秸秆床发酵系统同时处理打捆秸秆和猪粪废水是可行的,但需解决发酵后期秸秆上浮、导向性下降和进水短流等问题。     

A Market Study on the Anaerobic Waste-water Treatment Systems

This study analyzed global trends in the industrial use ofanaerobic wastewater treatment systems. Information on over 750anaerobic systems installed over the last two decades by three leading suppliers of anaerobic systems, namely ADI SystemsInc., Biothane Corporation, and Paques, showed exponential growthin the use of industrial anaerobic wastewater systemsinternationally up to the mid-1990s. After 1994, the number ofannual installations declined, and has been relatively constantover the last three years. The North American market was shown tobe relatively volatile, with no clear indication of futuregrowth, while the European market was found to be relativelymature. In North America, most of the anaerobic wastewatertreatment systems are serving breweries (26%), potato processingindustries (11%), or pulp and paper industries (9%). Ananalysis of the market history of the commercial anaerobic modelssuggests the phasing out of traditional UASB and fermentormodels, and the potential for growth of high-capacity and high-rate systems (>20 kg m^-3 d^-1) such as the BiothaneEGSB and the Paques Internal Circulation (IC) systems. Future efforts should focus on research into new designs for high-rate and high-capacity systems, and on the encouragement of economic incentivesfor industries implementing anaerobic wastewater treatmentsystems. A market study on other methods of wastewater treatment(e.g. aerobic treatment) is also recommended, to provide insightinto current economic trends in the area of environmental biotechnology.     

Removal of Remazol Red Rb by using Al (III) as Coagulant-Flocculant: Effect of Some Variables on Settling Velocity

This study addresses the research of the removal of a textile dye from aqueous solutions by using aluminum ions as coagulant-flocculant. A simulated textile wastewater was prepared from Remazol Red RB textile dye. The purpose of this study was to investigate the effects of temperature, pH, and concentrations of the cationic surfactant and electrolyte concentration on the settling velocity ofthe simulated textile wastewater. While investigating these factors, levels of variables were determined by considering the characteristicsof traditional textile wastewater like pH, temperature, and dye concentration. Although traditional coagulation-flocculation processesmake use of different aluminium salts as coagulant-flocculent, in this study, Al ions dissolved in pH and temperature of traditional textilewastewater were used. Furthermore, sludge volume index values (SVI) were determined and conductivity measurements carried out. The resultsshowed that, in the working range of these variables, the spectroscopic color measurement revealed 100% decolorization yieldof wastewater. In conclusion, researchers found that the optimum settling velocity conditions were as follows: low temperature (273K),surfactant concentration of 0.10 g L^-1, electrolyte concentration of 0.10 g L^-1, dye concentration of 0.025 g L^-1 and a pH of 10.05. Finally, by conducting experiments twice under the obtained optimum values, mean settling velocity was 0.014 m min^-1 and the mean sludge volume index 140 mL g^-1.     

基于遗传算法的不同光照条件下植被和土壤组分温度反演

为了提高地表土壤组分温度的反演精度,该研究利用ASTER反射光谱数据获取像元组分比,将直方图法引入遗传算法中,从而缩小了获取遗传算法最佳搜索参数的范围,并利用遗传算法对盈科研究区内地表非同温像元进行组分温度分解,对非同温像元下植被、遮阴土壤、光照裸土的组分温度进行模拟。该研究采用遗传算法直接对ASTER热红外数据进行地表混合像元组分温度分解的方法验证。结果表明,在考虑反射波段情况下,模拟的组分温度与地表同步实测温度的相对误差为7.63%～8.867%,在不考虑反射波段情况下,模拟的组分温度与地表同步实测温度的相对误差为8.955%～11.832%,表明了此方法在研究地表组分温度反演是可行性。该研究为地表组分温度反演提供新思路。     

Evaluation of plant bed filter ditches for the removal of T-N and T-P from eutrophic pond water containing particulate N and P

Cultivation of useful terrestrial and aquatic plant species in plant bed filter ditches enables to treat domestic wastewater in addition to resource recycling and amenity functions. We reported previously that a ditch planted with papyrus removed Nand P most effectively from artificial wastewater. We evaluated the effectiveness of plant bed filter ditches in the treatment of eutrophic pond water, which unlike artificial wastewater, contains particulate Nand P. Experimental ditches were planted with papyrus, African marigold, peppermint, and impatience. These plant species were effective in removing N and P from artificial wastewater and could be used by rural communities for the production of handicrafts, cut flowers, and ornamental purposes. The control ditch did not contain plants (plant-free ditch). Pond water was continuously supplied to the ditches at a loading rate of 0.6–0.9 g m^-2 d^-1 for Nand 0.2–0.35 g m^-2 d^-1 for P. In the plant-free ditch, particulate Nand P in the influent were removed by passage through the bed filter, unlike NO³-N and PO⁴-P. A larger amount of PO⁴-P was dissolved from particulate P in the bed filter. The planted ditches effectively removed NO³-N, PO⁴-P as well as particulate Nand P. The planted ditches were able to purify eutrophic pond water, resulting in clear water with a concentration below 0.3 mg L^-1 for N and 0.02 mg L^-1 for P, concentrations at which water bloom does not occur. The average removal rate of pollutants by the planted ditches during the experiment, except for the first 2 weeks, was 0.67 g m^-2 d^-1 for total N and 0.03 g m^-2 d^-1 for total P. We recommend that plant bed filter ditches containing papyrus and flowers be used for ornamental purposes and removal of N and P from pond water along with the supply of clear water as ornamental streams.     

基于温光效应的小白菜营养品质模拟模型研究

为了建立小白菜营养品质模型,本研究以小白菜品种“四月慢”为试材设计分期播种试验,测定不同温光条件下小白菜不同时期维生素C、纤维素、可溶性糖以及可溶性蛋白含量等营养品质指标,建立基于温光效应 (Light and temperature function,LTF)的小白菜营养品质数学模型,并利用独立试验资料对模型进行检验。结果表明：本模型对小白菜的维生素C、纤维素、可溶性糖以及可溶性蛋白含量的预测结果回归估计标准误差（RMSE）比辐热积法（Thermal effectiveness and photosynthetically active radiation,TEP）、积温法（Growing degree days,GDD）显著降低,与辐热积法相比,各指标的RMSE分别降低81.14%、77.46%、77.23%、75.53%,与积温法相比则分别降低77.15%、78.77%、79.90%、21.17%,表明模型的预测精度更高。本模型实测值与模拟值间的相关系数（r）均大于0.98,优于辐热积法和积温法的模拟结果,表明模拟值与实测值之间符合度较高。与传统的辐热积法和积温法相比,温光效应法显著提高了小白菜营养品质预测精度,可为耐弱光的温室作物营养品质模拟提供参考。     

Acid pulses from snowmelt at acidic cone pond,New Hampshire

A study was undertaken to examine whether ‘acid pulses’ from snowmelt created permanent changes in a pond's chemistry. Water samples were collected from clearwater acidic Cone Pond in the White Mountain National Forest, New Hampshire. The pond, inlet, and outlet were intensively sampled throughout winter and early spring 1983–84. Thaws brought more H⁺ into upper waters of the pond, but most was gone within a week. In contrast, SO₄ ^2? and Al showed dilution with increased streamflow into the pond, and NO₃ ^? was only detected in ice, slush, and surface waters. Bottom waters were anoxic throughout the winter and had pH 6.0 compared to 4.7 for most of the water column. Alkalinity at the bottom rose from 0 in November 1983 to 190 μeq L^?1 in April 1984. Between November and April the pond gained Al but lost SO₄ ^2? and H⁺. Most of the Al gain came after ice-out when loading through the inlet increased, but during the final snowmelt a temporary increase in Al concentration was also seen throughout the water column.     

基于温光效应的小白菜营养品质模拟模型研究*2

为了建立小白菜营养品质模型,本研究以小白菜品种“四月慢”为试材设计分期播种试验,测定不同温光条件下小白菜不同时期维生素C、纤维素、可溶性糖以及可溶性蛋白含量等营养品质指标,建立基于温光效应(Light and temperature function,LTF)的小白菜营养品质数学模型,并利用独立试验资料对模型进行检验。结果表明：本模型对小白菜的维生素C、纤维素、可溶性糖以及可溶性蛋白含量的预测结果回归估计标准误差（RMSE）比辐热积法（Thermal effectiveness and photosynthetically active radiation,TEP）、积温法（Growing degree days,GDD）显著降低,与辐热积法相比,各指标的RMSE分别降低81.14%、77.46%、77.23%、75.53%,与积温法相比则分别降低77.15%、78.77%、79.90%、21.17%,表明模型的预测精度更高。本模型实测值与模拟值间的相关系数（r）均大于0.98,优于辐热积法和积温法的模拟结果,表明模拟值与实测值之间符合度较高。与传统的辐热积法和积温法相比,温光效应法显著提高了小白菜营养品质预测精度,可为耐弱光的温室作物营养品质模拟提供参考。     

基于温度场模拟的铸件表面硼化物梯度耐磨材料成形机制

利用ANSYS10.0,对铸件表面硼化物梯度耐磨材料成形过程中温度场进行了模拟验证,对梯度耐磨材料不同部位的成形机制进行了分析研究,结果表明,模拟结果与试验结果较为吻合,合金粉块不同部位温度变化将影响复合材料的质量,内层及中间层温度高,高温持续时间长,熔合质量好,而对于最外层,温度较低(<1 000℃),高温持续时间短,尖角处温降快,导致这些部位复合材料熔合质量较差、缺陷较多。进一步研究表明,砂型材料的导热率及合金粉块内低熔点的熔合剂过多均会影响复合材料的质量。