Modelling Multi-Ion Transport in Saturated Soil and Parameter Estimation. II: Experimental

Multi-ion miscible displacement experiments were conducted

1 This paper is based on the M.S. thesis of the senior author. Chen Wenlin is now Research Associate at the Institute of Geography of the Academia Sinica, Beijing 100012, P.R. China.

with saturated soil columns under steady-state flow conditions. The experiments were carried out with four ionic species (Ca² Na⁺, SO₄2 and CI and the columns were 30 cm long. The experimental data were used to evaluate the multi-ion convective-dispersive miscible displacement model, developed in Part I of this study. Some parameters needed for this model were estimated with simplex and nonlinear least-square fitting methods. It was found that the model described the observed break through curves satisfactorily, when the soil matrix-solute interaction was described as an exchange process instead of an adsorption process.     

基于数据同化的土壤水力参数反演方法：研究进展与展望

土壤水力参数及其非均质性刻画关乎到诸多土壤与地下水等领域的量化模拟研究问题。受限于时间和采样成本,传统的直接测定方法并不能很好地解决这个问题。随着物联网技术的发展,与土壤水运动有关的一些状态表征量（如含水量和水头）已经能够通过传感器实时获得。如何充分融合这些观测数据信息,反演出土壤水力参数是当前的一个研究热点。数据同化方法能够通过融合观测数据与模型预测值信息,实现对模型参数的反演估计。本文系统分析了土壤水力参数不确定性的来源及测定方法,阐述了常用数据同化方法的基础理论及其在土壤水力参数反演方面的应用,并从计算效率和反演精度两方面着重论述了数据同化方法的最新前沿进展,最后探讨了数据同化方法未来的发展方向。研究表明：数据同化方法能够突破传统测定方法的限制,用于土壤水力参数及其非均质性刻画。尽管如此,由于土壤非饱和流模型的强非线性以及原位观测数据的相对稀缺性等问题的存在,当前数据同化方法的计算效率和反演精度还有待进一步提升。未来可从发展监督式降维方法、多源多尺度数据融合以及耦合物理规律的机器学习等方面深化土壤水力参数反演方法研究,这有利于农业土水管理、污染防治和修复等工作的合理开展。     

Wastewater Reclamation for Agricultural Reuse in Israel: Trends and Experimental Results

Water shortage and a deterioration in the quality of water resources in Israel have made necessary a national policy recommending reuse of practically all municipal wastewater in order to supply a major part of agricultural water demand. Two pilot-scale systems were operated and studied for several years. The first one consisted of an advanced treatment scheme incorporating a sequencing batch reactor (SBR) system with further deep-bed granular filtration. The second system was an SBR unit, for the purpose of optimizing nitrogen and phosphorus removal and testing further microfiltration of SBR effluents. The SBR process has been shown to be an efficient biological treatment method producing low Biochemical Oxygen Demand (BOD) and Total Suspended Solids (TSS) effluents. SBR effluents, even if loaded with high TSS concentrations, could be further purified in the filtration stage, producing low-turbidity effluents. Granular filtration experiments were carried out using a gravitational single-medium filter composed of uniformly-sieved quartz sand. It was found that most of the suspended solids were removed in the top 10 cm of the filter bed. Influent turbidity was found to be the main parameter affecting the process, while filtration rate had only a minor effect. Microfiltration of SBR effluents showed highly efficient removal of turbidity and pathogens. Advanced mathematical models were developed and calibrated for both the biological process and for the granular filtration process.     

Anaerobic Fluidized Bed Degradation and the Development of a Kinetic Model for a Particulate Organic Matter Enriched Wastewater Sludge

The starch manufacturing industrial units, such as sago mills,both in medium and large scale, suffer from inadequate treatment and disposal problems due to high concentration of suspended solids present in the sludge. A laboratory scale study was conducted to investigate the viability of anaerobic treatment of sago waste sludge, enriched in particulate organicmatter, using a fluidized bed reactor. The start-up of the reactor was carried out using a mixture of digested supernatantsewage sludge and cow dung slurry in different proportions. The effect of operating variables such as COD of the effluent, bed expansion, minimum fluidization velocity on efficiency oftreatment and recovery of biogas was investigated. The maximum efficiency of treatment was found to be 82% and the nitrogen enriched digested sludge was recommended for agricultural use. A kinetic model was developed for the degradation of particulate organic matter using the general kinetic equation [dS/dt = K _HC SX_C] which allowed for a more accurate mathematical representation of the hydrolysis process. Analysing data from a series of batch tests, the best fit value of C was found to be in the range 0.43 to 0.62.     

Advances in Heterogeneous Photocatalytic Degradation of Phenols and Dyes in Wastewater: A Review

The heterogeneous photocatalytic water purification process has gained wide attention due to its effectiveness in degrading and mineralizing the recalcitrant organic compounds as well as the possibility of utilizing the solar UV and visible light spectrum. This paper aims to review and summarize the recently published works in the field of photocatalytic oxidation of toxic organic compounds such as phenols and dyes, predominant in wastewater effluent. In this review, the effects of various operating parameters on the photocatalytic degradation of phenols and dyes are presented. Recent findings suggested that different parameters, such as type of photocatalyst and composition, light intensity, initial substrate concentration, amount of catalyst, pH of the reaction medium, ionic components in water, solvent types, oxidizing agents/electron acceptors, mode of catalyst application, and calcinations temperature can play an important role on the photocatalytic degradation of organic compounds in water environment. Extensive research has focused on the enhancement of photocatalysis by modification of TiO₂ employing metal, non-metal, and ion doping. Recent advances in TiO₂ photocatalysis for the degradation of various phenols and dyes are also highlighted in this review.     

Advanced Oxidation Processes for Wastewater Treatment: State of the Art

The protection and conservation of natural resources is one of the main priorities of modern society. Water is perhaps our most valuable resource, and thus should be recycled. Many of the current recycling techniques for polluted water only concentrate the pollutant without degrading it or eliminating it. In this sense, advanced oxidation processes are possibly one of the most effective methods for the treatment of wastewater containing organic products (effluents from chemical and agrochemical industries, the textile industry, paints, dyes, etc.). More conventional techniques cannot be used to treat such compounds because of their high chemical stability and/or low biodegradability. This article describes, classifies, and analyzes different types of advanced oxidation processes and their application to the treatment of polluted wastewater.     

Modelling Multi-Ion Transport in Saturated Soil and Parameter Estimation. I: Theory

A coupled convective-dispersive model was developed to describe the solute movement of four ionic species (Ca²⁺, Na⁺, SC₄² and CI) through soil. The model considers precipitation and dissolution of calcium sulfate as well as cation exchange or adsorption during steady-state water flow in saturated soil columns. With the model hypothetical miscible displacement experiments were carried out. The governing partial differential equations were solved numerically with an implicit Crank-Nicolson scheme. With the use of obtained results the effect of various model parameters on the shape of the calculated breakthrough curves was investigated. It was found that the processes of dissolution and precipitation, cation exchange or adsorption do have a definite influence on the shape of the breakthrough curves.     

设施土壤中三唑酮降解动力学研究

经25℃下培养1个月,采用GC/MS定量监测设施土壤和无菌土壤中三唑酮和降解产物三唑醇的含量变化。结果表明设施土壤中三唑酮的降解符合热力学方程,半衰期为15.2 d,无菌土壤处理后三唑酮的半衰期为39.4 d。土壤中降解产物三唑醇有立体选择体,在设施土壤中三唑醇的对映体选择值(EF)为4,无菌土壤中三唑醇的EF值为2。三唑醇的降解符合一元三次方程,设施土壤中三唑醇在第7 d达到最高点后含量逐步降低,无菌处理土壤中三唑醇含量最高点出现在第14 d。     

Using a Numerical Model to Track the Discharge of a Wastewater Treatment Plant in a Tidal Estuary

Along the coast of Maine, USA, there are numerous wastewater treatment plants that discharge their treated effluents into a river estuary which is shared by commercial fishing and shellfish harvesting. Occasionally, there can be failures or bypasses of treatment plants that lead to untreated or partially treated sewage flowing into shellfish harvesting waters. To prevent any toxic contamination of harvested shellfish, a prohibitive zone is established around the treatment plant where shellfish harvesting is prohibited. The U.S. Food and Drug Administration has conducted numerous dye studies on both coasts of the USA to determine these prohibitive zones, based on the guidelines of the National Shellfish Sanitation Program. In May 2010, the FDA conducted such a dye study at the Yarmouth, Maine wastewater treatment plant. The results are compared with a numerical coastal model that provides the velocity field for the currents around the treatment plant. This model includes a diffusion equation to simulate dye dispersion from a point source which is used to determine the prohibitive zone. The numerical model shows good correlation with the FDA dye study report and establishes a prohibitive zone for commercial harvesting in keeping with that of the FDA study. The benefits of the numerical model include sampling at thousands of locations simultaneously, seasonal changes in river volumes, and changes in plant discharge volumes.     

黄绵土钾含量高光谱估算模型研究

为了研究可见/近红外光谱法估算渭北旱塬区黄绵土钾含量的可行性,以陕西省乾县试验田采集的120个土壤样品为研究对象,在室内进行土壤全钾、速效钾含量及反射光谱数据测量的基础上,应用多元线性回归(MLR)和偏最小二乘回归(PLSR)方法建立土壤钾含量的估算模型,并用独立样本进行验证。结果表明,以土壤光谱反射率一阶微分(DSSR)为自变量建立的多元线性回归模型(MLR)能进行土壤全钾含量准确估算。以波段深度一阶微分(DBD)为自变量建立的PLSR模型,验证集的决定系数(R2pre)大于0.90,预测均方根误差(RMSEpre)等于0.054,预测相对分析误差(RPDpre)等于3.310,是估算土壤全钾含量的最优模型;而以DSSR为自变量建立的PLSR模型,RPDpre值为1.619和1.572,是估算土壤速效钾含量的最优模型。本研究表明可见/近红外光谱结合多元线性回归和偏最小二乘回归方法能对渭北旱塬区黄绵土全钾含量进行快速、准确估算,但对速效钾含量仅能进行粗略估算。     

Microalgal Dynamics in Batch Reactors for Municipal Wastewater Treatment Containing Dairy Sewage Water

This study investigates the microalgal community dynamics associated with changes in municipal wastewater quality and discharges from the dairy industry in central Veracruz, Mexico, using an experimental stabilization-reactors system. Thirty one species of microalgae were recorded and 15 physicochemical variables were measured daily over 25 days in pretreated water. The biomass of microalgal groups displayed significant negative correlations with biochemical oxygen demand (BOD), chemical oxygen demand (COD) and total suspend solids (TSS). Conversely, a significant positive correlation was found with dissolved oxygen, pH and nitrates. Using the Canonical Correspondence Analysis we identified an initial anaerobic phase (Phase I), characterized by high BOD, TSS and COD, ammonium and faecal coliforms. This was followed by a transition phase (Phase II), an initial aerobic phase (Phase III), when water quality improved considerably, and finally an aerobic phase (IV) with a high percent reduction in these parameters and almost complete organic load removal. The most abundant species associated with these phases were Arthrospira jenneri (Cyanophyceae) and Coccomonas sp. (Chlorophyceae) in Phase I; Polytomella sp. (Chlorophyceae) in Phase II; Polytoma tetraolare, Chlamydomonas caeca (Chlorophyceae) and some Cyanophyceae including Geitlerinema, Synechocystis, Cyanobium and Glaucospira in Phase III; Carteria sp. (Chlorophyceae), Lepocynclis ovum and Euglena clavata (Euglenophcyeae) in Phase IV. Maximum richness, diversity, and biomass levels occurred during the aerobic phase. Similar to other wastewater treatment systems the high succession rates decreased with reactor stabilization. These findings provide statistical evidence on the suitability of certain microalgae species as indicators of wastewater stabilization reactor status and effluent quality.     

Assessment of Luffa cylindrica as Support in Biofilms Reactors for the Biological Treatment of Domestic Wastewater

A simultaneous treatment of BOD, phosphorous and ammonia in artificial wastewater was carried out in biofilm reactors with Luffa cylíndrica as organic support and compared with PVC's support under variations of dissolved oxygen of 1.5 a 3.0 mg l^?1 in the same reactor. During semicontinous treatment, the removal of BOD (92.5%) with Luffa cilíndrica was higher than PVC support (80%). Nitrification only existed at levels of oxygen of 3 mg l^?1, showed in the effluent a final concentration of ammonium of 17 and 19 mg l^?1 for Luffa cilíndrica and PVC support, respectively. In reactors with Luffa cilíndrica a higher percentage of P removal (40%) was reached, while no elimination in reactors with PVC was observed. The formation of anaerobic-aerobic zones inside the natural support probably allowed the increase in the efficiency of removal of phosphorous. Oxidation of organic matter, P removal and nitrification can be achieved with the variation of oxygen inside of the same biofilm reactor using L. cylindrical as support material.     

Ibuprofen Genotoxicity in Aquatic Environment: An Experimental Model Using Oreochromis niloticus

Medicines and their metabolites have been found as water contaminants at very low concentrations; moreover, there is no extensive toxicological data to determine the risks associated with their occurrence in water resources. The ibuprofen genotoxicity potential to the Oreochromis niloticus fish (Tilapia), due to nanograms per liter exposure, was evaluated using the micronucleus test. Acute (48 h) and sub-chronic assays (10 days) were carried out at 300 ng/L ibuprofen aquatic concentration comparing with the negative control group (without treatment), with eight animals per group. The results were assessed from the average of triplicate analyses. The micronucleus frequency in peripheral blood of fish was determined using a sample size of 3,000 erythrocytes per animal. Significance was defined using t test (p????0.05). The bioassay results showed a statistically significant increase in the frequency of micronuclei for both exposure times in comparison to the negative control. The micronucleus frequency observed for the sub-chronic tests was higher than the one identified in the acute assays. The observed ibuprofen genotoxic effects demonstrated an aquatic environmental risk of this pharmaceutical, which occurs for the used fish experimental model in lower concentration than previously described for other aquatic organisms.     

机器学习算法和Hargreaves模型在四川盆地ET0计算中的比较

以四川盆地中部遂宁气象站2001-2010年逐日温度资料和大气顶层辐射（Ra）为输入参数,以FAO-56 Penman-Monteith（PM）模型计算的参考作物蒸散量（ET0）为标准,分别利用广义回归神经网络（GRNN）和小波神经网络（WNN）两种机器学习算法建立ET0模拟模型,并对GRNN、WNN和Hargreaves（HS1）与两种改进的Hargreaves（HS2和HS3）模型的ET0模拟效果进行对比分析,利用2011-2014年数据对各模型模拟精度进行验证,分析仅有温度资料时不同模型在四川盆地的适用性。结果表明：GRNN模型和WNN模型均具有较强的适用性,GRNN模型均方根误差（RMSE）、模型效率系数（Ens）和决定系数（R2）分别为0.395mm×d-1、0.924和0.902,WNN模型分别为0.401mm×d-1、0.911和0.901,且两种模型计算精度均高于HS1（1.05mm×d-1、0.885和0.334）、HS2（0.652mm×d-1、0.892和0.736）和HS3（0.550mm×d-1、0.881和0.812）模型。模型适用性验证进一步表明,GRNN和WNN模型在四川盆地西部和东部也具有较好的适用性,在输入参数中引入Ra能提高模型的模拟精度。因此,GRNN和WNN可以作为气象资料缺失条件下四川盆地ET0计算的推荐模型,且GRNN计算精度高于WNN,可优先选用。     

Use of Ceramic Membranes in a Membrane Filtration Supported by Coagulation for the Treatment of Dairy Wastewater

Water, Air, & Soil Pollution - A novel adsorbent was prepared by introducing xanthate group onto pristine multi-walled carbon nanotubes (MWCNTs) for removing Pb (II) from aqueous solution. The...     

Macrophyte Sorption and Bioconcentration of Elements in a Pilot Constructed Wetland for Flue Gas Desulfurization Wastewater Treatment

The sorption and bioconcentration of Hg, Se, and As were measured in Schoenoplectus californicus and Typha angustifolia in a pilot constructed wetland receiving wastewater inflows containing these elements at potentially hazardous levels. Results indicated that these species bioconcentrated Hg, Se, and As at factors of up to 1,911, 10,981, and 4,927, respectively. Plant tissue concentrations decreased as Hg, Se, and As were translocated from the roots to the aerial portions of the plant. Greatest element concentrations in S. californicus were found in roots, indicating that an exclusion mechanism may be responsible for element tolerance by this plant species. Greater root:shoot transfer of Hg, Se, and As was observed with T. angustifolia than with S. californicus, suggesting that element tolerance was more likely due to an internal detoxification mechanism. To completely assess ecological risks associated with the use of constructed wetlands, contaminant bioavailability for plant uptake, translocation, and bioconcentration must be considered.     

Impact and Publication Patterns: A Model for Examining Resources in an International Context

ABSTRACT

The goal of this study was to determine the international impact of publications from a variety of institutes of parasitology and to evaluate sources for research in order to improve collection development decisions. Two methods were developed: a method of providing academic librarians with information on the relative impact of their institution when compared with other similar institutions and a method for comparing research sources on an international level. Using articles indexed in ISI Web of Science, twelve parasitology research centers from five countries were compared over a five-year period for number of publications produced and times each of the journal articles was cited.     

基于高光谱参数建立苗期高温条件下草莓叶片叶绿素含量估算模型

以“红颜”草莓（Fragaria×ananassa Duch“Benihope”）为试材,于2021年9−11月在人工气候室进行苗期（9～12片真叶,叶长≥5cm）动态高温环境控制实验,日最高温度以32℃为起点,设置日最高气温/日最低气温分别为32℃/22℃、35℃/25℃、38℃/28℃和41℃/31℃共4个水平,持续时间分别为2d、5d、8d和11d,以28℃/18℃为对照（CK）。试验期间空气相对湿度60%～70%,光周期12h/12h（6：00−18：00）,光照强度800μmolm⁻²s⁻¹。测定不同处理下叶片叶绿素含量及高光谱反射率,对原始光谱进行变换,从而细化光谱特征信息。在相关分析的基础上,建立原始和一阶敏感波段植被指数,进而筛选出表征叶绿素含量的光谱特征参数,以期构建叶绿素含量最佳估算模型。结果表明：（1）随着温度的升高和高温持续时间的延长,草莓叶片叶绿素a、叶绿素b和总叶绿素（a+b）含量呈下降趋势。（2）草莓叶片原始光谱在可见光区域均存在绿峰和红谷,除绿峰和红谷外各处理间差异不明显,高温条件下的近红外区域反射率与CK相比出现不同程度的上升。与原始光谱相比,一阶导数光谱曲线震荡更剧烈,且能够显著突出红边参数特征,各处理的红边位置λ_r稳定在716nm,红边幅值D_r与红边面积S_r差异显著;而在连续统去除光谱中各处理的绿峰（550nm附近）和红谷（675nm附近）被完全突显出来。（3）在光谱反射率与叶绿素含量相关性分析的基础上,选取原始光谱与一阶导数光谱在可见光和近红外波段相关性最强的R₇₄₇、R₈₀₀和R'₇₁₆、R'₉₀₆为敏感波段组合,构建植被指数。（4）PVI、MSAVI、TSAVI、TSAVI'、DVI'、MSAVI'、PVI'、SAVI'、D_r和S_r指数与叶绿素含量相关性达极显著水平,可作为表征设施草莓叶片叶绿素含量对苗期高温胁迫响应的高光谱特征参数。其中以TSAVI、DVI'和PVI'植被指数建立的逐步回归模型为叶绿素含量最佳估算模型,其决定系数（R²）为0.843,均方根误差（RMSE）为0.379,相对误差（RE）为12.65%。