Towards a better hydraulic cleaning strategy for ultrafiltration membrane fouling by humic acid: Effect of backwash water composition

As a routine measurement to alleviate membrane fouling, hydraulic cleaning is of great significance for the steady operation of ultrafiltration（UF） systems in water treatment processes. In this work, a comparative study was performed to investigate the effects of the composition of backwash water on the hydraulic cleaning performance of UF membranes fouled by humic acid（HA）. Various types of backwash water, including UF permeate, Milli-Q water, Na Cl solution, CaCl_2 solution and HA solution, were compared in terms of hydraulically irreversible fouling index, total surface tension and residual HA. The results indicated that Milli-Q water backwash was superior to UF permeate backwash in cleaning HA-fouled membranes, and the backwash water containing Na＋or HA outperformed Milli-Q water in alleviating HA fouling. On the contrary, the presence of Ca^（2＋） in backwash water significantly decreased the backwash efficiency. Moreover, Ca^（2＋） played an important role in foulant removal, and the residual HA content closely related to the residual Ca^（2＋） content.Mechanism analysis suggested that the backwash process may involve fouling layer swelling, ion exchange, electric double layer release and competitive complexation. Ion exchange and competitive complexation played significant roles in the efficient hydraulic cleaning associated with Na＋and HA, respectively.

Experimental Study on the Effect of Sediment Composition Ratio on Shallow Water Delta

1 Introduction Shallow water delta in the middle-newborn Stratum Widely developed with huge oil and gas in China(Hu Shengwu et al.,2013).The control factors on the deltadevelopment like Climate,sea level,tectonic subsidence,sediment supply(flow,type),the geometric characteristics of the upstream river,the energy(wave,

Research and Application of Ecological Outdoor Ground Structure with Composite Water Storage and Drainage Function

In order to solve the problems of surface runoff increase,water accumulation in rainy days and urban heat island effect,an ecological outdoor ground structure with composite water storage and drainage functions was studied and applied in this paper:Through the comprehensive design of road ground,road inspection well,garden inspection well and drainage pipe network,it can quickly store and drain ground water,alleviate the urban heat island effect,realize plant infiltration irrigation,and achieve the purpose of saving water and energy.

Study on the Urbanization Process of Kunming City and Its Impact on the Water Environment of Dianchi Lake

[ Objective] We aimed to analyze the urbanization process of Kunming City and its impact on the water environment of Dianchi Lake. [ Method ] Using the Analytic Hierarchy Process （AHP）, we assessed the urbanization leve of Kunming in 1998 -2008 based on composite indicator evaluation system. Afterwards, we calculated water pollution composite index of Dianchi Lake and introduced the EKC to set up a coupling relation- ship model between the urbanization level and water environment quality. [ Result] During 1998 -2008, the urbanization level of Kunming increased gradually, that is, it was lower than 30.0% before 2002, with slow growth; at the later stage, it grew fast, and reached 75.0% in 2008. Water pol- lution composite index of Dianchi Lake showed that Dianchi Lake was polluted seriously, especially Caohai. From the EKC, we can see that the re- lationship curves between the urbanization level of Kunming and water pollution composite index of Dianchi Lake were akin to inversed U shapes and still at an antagonistic stage at present. [ Condusion] The research could provide scientific references for discussing the relationship between urban- ization process and water environment.

Water-conducting Characteristics and Micro-dynamic Self-adjusting Behavior of Polyacrylamide/Montinorillonite Coating

A water-conducting polyacrylamide/montmorillonite coating was prepared by solutionblending.The coating was coated on fiber and then composited with polymer to form a composite film material that used for water saving and tree planting in arid and desert regions.The coating＇s water-conducting characteristics and dynamic self-adjusting behavior were investigated by Fourier transform infrared（FTIR）spectroscopy,thermal analysis（TG-DTA）,and environmental scanning electron microscopy（ESEM）.The results showed that the coating＇s water-conducting rate increased but water-retention capacity weakened with increasing montmorillonite content.The water-loss rate was positively related to temperature and negatively related to soil moisture.Water potential greatly influenced the water-conducting rate of the coating during its water conduction process.When the coating was at a low water potential,the montmorillonite particles interconnected and water was conducted quickly via montmorillonite layers,whereas when the coating was at a high potential,the montmorillonite particles disconnected and water was conducted slowly via the swelled polyacrylamide net structure.The rate can be regulated by changing the proportion of polyacrylamide and montmorillonite to guarantee a reasonable water supply for trees and make trees easier to survive.Thus,the survival rate of trees can be increased and the use of water resources can be significantly reduced.

Genesis and Quality of Groundwater in the Southeastern Region of Southern Vietnam

The origin and quality of groundwater in the Southeastern region （belongs to Southern Plain） were identified by using isotopic techniques and geochemical analysis. Groundwater samples were collected from 7 aquifers： the Holocene, upper Pleistocene, middle Pleistocene, lower Pleistocene, upper Pliocene, middle Pliocene and Miocene aquifers. The water isotopic compositions （82H and 8180） were determined to elucidate the origin and the interaction between surface water and groundwater studies. Transit time （age） of the groundwater samples was determined to explain the direction of groundwater flow. The dating techniques included 3H and ^14C isotopes measurement, followed by a correction for the initial ^14C-activity by the ^13C-composition （^13C） in TDIC （Total Dissolved Inorganic Carbon）. Geochemical parameters of the groundwater samples were measured either directly in the field or in the laboratory. The results showed that the groundwater from the Holocene and upper Pleistocene aquifers was most recharged from the local meteorological and hydrological systems, including local precipitation, fiver and reservoirs. Thus, it has short transit time and its stable isotopic composition is spread around the local meteoric waterline and lines for rivers or reservoirs water. The groundwater in the deeper aquifers： middle and lower Pleistocene, and Neogene aquifers has old age up to 22.5 ka BP. Its water seems to be recharged from the areas with an altitude from 600 to 700 m higher to the Neogene deposit layer altitude. The groundwater in the SE SP （South-Eastern Southern Plain） region has a high quality. The water type is Na-Ca-Mg-HCO3 with low content of chloride and TDS （Total Dissolved Solids）. Calcite/dolomite and gypsum dissolution, organic matter decomposition and sequence of red-ox reactions proceeding through different electron acceptors sediment were controlled the chemistry of the groundwater in the study region.

Preparation and Characterization of CA-MA Eutectic/Silicon Dioxide Nanoscale Composite Phase Change Material from Water Glass via Sol-Gel Method

This work mainly involved the preparation of a nano-scale form-stable phase change material（PCM） consisting of capric and myristic acid（CA-MA） binary eutectic acting as thermal absorbing material and nano silicon dioxide（nano-SiO_2） serving as the supporting material. Industrial water glass for preparation of the nano silicon dioxide matrix and CA-MA eutectic mixture were compounded by single-step sol-gel method with the silane coupling agent. The morphology, chemical characterization and form stability property of the composite PCM were investigated by transmission electron microscopy（TEM）, scanning electron microscopy（SEM）, Fourier-transform infrared（FT-IR） spectroscopy and polarizing microscopy（POM）. It was indicated that the average diameter of the composite PCM particle ranged from 30-100 nm. The CA-MA eutectic was immobilized in the network pores constructed by the Si-O bonds so that the composite PCM was allowed no liquid leakage above the melting temperature of the CA-MA eutectic. Differential scanning calorimetry（DSC） and thermogravimetric analysis（TGA） measurement were conducted to investigate the thermal properties and stability of the composite PCM. From the measurement results, the mass fraction of the CA-MA eutectic in the composite PCM was about 40%. The phase change temperature and latent heat of the composite were determined to be 21.15 ℃ and 55.67 J/g, respectively. Meanwhile, thermal conductivity of the composite was measured to be 0.208 W·m^（-1）·K^（-1） by using the transient hot-wire method. The composite PCM was able to maintain the surrounding temperature close to its phase change temperature and behaved well in thermalregulated performance which was verified by the heat storage-release experiment. This kind of form-stable PCM was supposed to complete thermal insulation even temperature regulation by the dual effect of relatively low thermal conductivity and phase change thermal storage-release properties. So it can be formulated that the nanoscale CA-MA/SiO_2 composite PCM with the form-stable property, good thermal storage capacity and relatively low thermal conductivity can be applied for energy conservation as a kind of thermal functional material.

Analysis of Shop cold water stability of asphalt concrete composite

He cold asphalt concrete is laid composite that combines the advantages of rigid cement concrete and asphalt concrete flexible pavement materials and new waterproof materials, and it is also known as semi-rigid concrete or semi-rigid waterproof concrete. Cold paved asphalt concrete composite retains the advantages of rigid and flexible waterproof material waterproof material which abandoned both of their inadequacies, is waterproof material with a wide range of space research and application prospects. This study immersion Marshall test and freeze-thaw split test two test methods for cold-laid asphalt concrete composite conducted a comprehensive analysis of the stability of the water; the highest draw AC1-6 AC-20 immersion Marshall stability and 20.59, respectively, by testing MPa and 19.96 Mpa, freeze-thaw splitting strength to reach the highest ratio of 91% and 93% respectively, the value specification can be met, and through the analysis of the test data to identify the content of the asphalt cement content and cold water laid asphalt compound affect the stability of the peak will occur, so that it can be combined with concrete interfacial adhesion studies to further the comprehensive and accurate assessment of water resistance of the material.

STUDY ON THE CHEMICAL CHARACTERISTICS OF POLLUTING FOG IN GUANGZHOU AREA IN SPRING

Samples of fog water collected in the area of Guangzhou during February, March and April of 2005 are used in this work to study the chemical composition of fog water in polluting fog there. Three typical episodes of polluting fog are analyzed in terms of ionic concentration and their possible sources. It is found that the concentration of various ions in fog water is much higher than those in rainwater. Fog not only blocks visual range but contains liquid particles that result in high degree of pollution and are very harmful to human health. SO4= is the anion with the highest concentration in fog water, followed by NO3-. For the cation, Ca++ and NH4+ are the highest in concentration. It is then known that rainwater is more acidic than fog water, indicating that ionic concentration of fog water is much higher than that of rainwater, but there are much more buffering materials in fog water, like NH4+ and Ca++. There is significant enrichment of Ca++, SO4=, and Mg++ in fog water. In the Guangzhou area, fog water from polluting fog is mainly influenced continental environment and human activity. The episodes of serious fog pollution during the time have immediate relationships with the presence of abundant water vapor and large amount of polluting aerosol particles.

Cooling System Design and Thermal Analysis of Modular Stator Hybrid Excitation Synchronous Motor

Hybrid excitation synchronous motor has the advantages of uniform and adjustable electromagnetic field, wide speed range and high power density. It has broad application prospects in new energy electric vehicles, wind power generation and other fields. This paper introduces the basic structure of hybrid excitation motor with modular stator, and analyzes the operation principle of hybrid excitation motor. The cooling structure of the water-cooled plate is designed, and the effects of the thickness of the water-cooled plate and the number of water channels in the water-cooled plate on the heat dissipation capacity of the water-cooled plate are analyzed by theoretical and computational fluid dynamics methods. The effects of different water cooling plate structures on water velocity, pressure drop, water pump power consumption and heat dissipation capacity were compared and analyzed. The influence of different inlet flow velocity on the maximum temperature rise of each part of the motor is analyzed, and the temperature of each part of the motor under the optimal water flow is analyzed. The influence of the traditional spiral water jacket cooling structure and the water-cooled plate cooling structure on the maximum temperature rise of the motor components is compared and analyzed. The results show that the water-cooled plate cooling structure is more suitable for the modular stator motor studied in this paper. Based on the water-cooled plate cooling structure, the air-water composite cooling structure is designed, and the effects of the air-water composite cooling structure and the water-cooled plate cooling structure on the maximum temperature rise of each component of the motor are compared and analyzed. The results show that the maximum temperature rise of each component of the motor is reduced under the air-water composite cooling structure.

Health Risk Assessment of Groundwater Pollution—A Case Study of Typical City in North China Plain

This article presents an application of assessing human health risk in typical city of North China plain.Combined with water quality and multi-element analysis,Pb,Cd,Cr^6＋,Mn,NO3^-,F^-,and As in groundwater samples were chosen to be used for human health risk assessment of drinking water pathway and dermal contact pathway,and results show a good effect.Results indicate that（1） poor water quality is caused by salinity and hardness overstandard;（2） in noncarcinogenic risk,samples that do not pose noncarcinogenic risk only account for 28.46%;in carcinogenic risk,samples that do not pose carcinogenic risk account for 73.08%;（3） the noncarcinogenic risk in the study area decreased in the following order：NO3^-〉Mn〉As〉F-〉Cr^6＋〉Cd〉Pb and the carcinogenic risk of the study area de-creased in the following order：As〉Cd=NO3^-=Mn=F-=Cr^6＋=Cd=Pb=0,because the slop factors were not available for the other pollutants,except for As;and（4） in terms of whole study area,the main contrib-ute order of drinking water pathway and dermal contact pathway in human body is drinking water pathway〉dermal contact pathway.

Geochemical characteristics of modern hot springs from northwest Hunan

The studies of chemical compositions of modern hot spring water and gases,isotopic compositions of H_2O,He,Ar,CH_4,CO_2 in northwest Hunan show that the chemical characteristics of spring water are markedly different,which indicates the difference of background value of country rocks and the dif- ference of the effect of water-rock reaction.The geothermal systems in the studied regions are middle-high temperature geothermal systems.The distributions of springs are controlled by the press and press-shear faults that do not dissect deeply to the mantle.The hot spring water is of meteoric water.The origin of ma- terials in the hot springs is correlated with the sedimentary rocks.