Enhanced removal of organic matter and typical disinfection byproduct precursors in combined iron–carbon micro electrolysis-UBAF process for drinking water pre-treatment

The organic matter and two types of disinfection byproduct(DBP) precursors in micropolluted source water were removed using an iron–carbon micro-electrolysis(ICME)combined with up-flow biological aerated filter(UBAF) process. Two pilot-scale experiments(ICME-UBAF and UBAF alone) were used to investigate the effect of the ICME system on the removal of organic matter and DBP precursors. The results showed that ICME pretreatment removed 15.6% of dissolved organic matter(DOM)and significantly improved the removal rate in the subsequent UBAF process. The ICME system removed 31% of trichloromethane(TCM) precursors and 20% of dichloroacetonitrile(DCAN) precursors. The results of measurements of the molecular weight distribution and hydrophilic fractions of DOM and DBP precursors showed that ICME pretreatment played a key role in breaking large-molecular-weight organic matter into low-molecular-weight components, and the hydrophobic fraction into hydrophilic compounds, which was favorable for subsequent biodegradation by UBAF.Three-dimensional fluorescence spectroscopy(3D-EEM) further indicated that the ICME system improved the removal of TCM and DCAN precursors. The biomass analysis indicated the presence of a larger and more diverse microbial community in the ICME-UBAF system than for the UBAF alone. The high-throughput sequencing results revealed that domination of the genera Sphingomonas, Brevundimonas and Sphingorhabdus contributed to the better removal of organic matter and two types of DBP precursors. Also, Nitrosomonas and Pseudomonas were beneficial for ammonia removal.     

Insight into the adsorption of tetracycline onto amino and amino–Fe functionalized mesoporous silica: Effect of functionalized groups

In order to study the influences of functionalized groups onto the adsorption of tetracycline (TC), we prepared a series of amino and amino–Fe^3 + complex mesoporous silica adsorbents with diverse content of amino and Fe^3 + groups (named N,N-SBA15 and Fe-N,N-SBA15). The resulting mesoporous silica adsorbents were fully characterized by X-ray powder diffraction, Fourier transform infrared spectrometer and N₂ adsorption/desorption isotherms. Furthermore, the effects of functionalized groups on the removal of TC were investigated. The results showed that the periodic ordered structure of SBA-15 was maintained after modification of amino/Fe^3 + groups. The functionalized amino groups decreased the adsorption capacity while the coordinated Fe^3 + increased the adsorption capacity. The adsorption kinetics of TC fitted pseudo-second-order model well and the equilibrium was achieved quickly. The adsorption isotherms fitted the Langmuir model well and with the Fe^3 + content increased from 3.93% to 8.26%, the Q_max of the adsorbents increased from 102 to 188 mmol/kg. The solution pH affected the adsorption of TC onto amino complex adsorbents slightly while influenced the adsorption onto Fe-amine complex adsorbents greatly. The adsorption of TC on SBA15 and N,N-SBA15 may be related to the formation of outer-sphere surface complexes, while the adsorption of TC onto Fe-N,N-SBA15 was mainly attributed to the inner-sphere surface complexes. This study could offer potential materials that have excellent adsorption behavior for environmental remediation and suggested useful information for the preparing other adsorbents in environmental applications.     

What drives the change of nitrogen and phosphorus loads in the Yellow River Basin during 2006-2017?

The Yellow River Basin (YRB) plays a very important role in China's economic and social development and ecological security. In particular, the ecosystem of the YRB is sensitive to climate change. However, the change of nutrient fluxes in this region during the past years and its main driving forces remain unclear. In this study, a hydrologic model R System for Spatially Referenced Regressions on Watershed Attributes (RSPARROW) was employed to simulate the spatio-temporal variations in the fluxes of total nitrogen (TN) and total phosphorus (TP) during the period of 2006-2017. The results suggested that the TN and TP loads increased by 138% and 38% during 2006-2014, respectively, and decreased by 66% and 71% from 2015 to 2017, respectively. During the period of 2006-2017, the annual mean fluxes of TN and TP in the YRB were in the range of 3.9 to 591.6 kg/km²/year and 1.7 to 12.0 kg/km²/year, respectively. TN flux was low in the upstream area of the Yellow River, and presented a high level in the middle and lower reaches. However, the flux of TP in Gansu and Ningxia section was slightly higher than that in the lower reaches of the Yellow River. Precipitation and point source are the key drivers for the inter-annual changes of TN loads in most regions of the YRB. While the inter-annual variations of TP loads in the whole basin are mainly driven by the point source. This study demonstrates the important impacts of climate change on nutrient loads in the YRB. Moreover, management measures should be taken to reduce pollution sources and thus provide solid basis for control of nitrogen and phosphorus in the YRB.     

Effects of nature organic matters and hydrated metal oxides on the anaerobic degradation of lindane,p,p''''-DDT and HCB in sediments

IntroductionLindane ,p,p’ DDTandHCBaresemivolatileandlipophilic ,andtheyfallintotheclassofcompoundsdescribedaspersistentorganicpollutants.Moreover,thesecompoundshavebeenidentifiedaspotentendocrinedisrupters(Smith ,2 0 0 2 ;Willett,1 998;Robert,2 0 0 1 ) .Ithasbeenreportedchlorinatedorganiccompoundscanbedecomposedveryslowlyinsedimentsthroughvariousreactions(Niesl,1 990 ) .Factorsinfluencingthebiodegradationofcompoundsarevarious.Amongthem ,itwasreportedthattheeffectsofnaturalorganicmatters…     

Insight into the adsorption of tetracycline onto amino and amino–Fe~(3+) gunctionalized mesoporous silica: Effect of functionalized groups

In order to study the influences of functionalized groups onto the adsorption of tetracycline,we prepared a series of amino and amino–Fe~(3+)complex mesoporous silica adsorbents with diverse content of amino and Fe~(3+)groups(named N,N-SBA15 and Fe-N,N-SBA15).The resulting mesoporous silica adsorbents were fully characterized by X-ray powder diffraction(XRD),Fourier transform infrared spectrometer(FTIR)and N_2adsorption/desorption isotherms.Furthermore,the effects of functionalized groups on the removal of TC were investigated.The results showed that the periodic ordered structure of SBA-15 was maintained after modification of amino/Fe~(3+)groups.The functionalized amino groups decreased the adsorption capacity while the coordinated Fe~(3+)increased the adsorption capacity.The adsorption kinetics of TC fitted pseudo-second-order model well and the equilibrium was achieved quickly.The adsorption isotherms fitted the Langmuir model well and with the Fe~(3+)content increased from 3.93%to 8.26%,the Q_(max)of the adsorbents increased from 102 to 188 mmol/kg.The solution p H affected the adsorption of TC onto amino complex adsorbents slightly while influenced the adsorption onto Fe-amine complex adsorbents greatly.The adsorption of TC on SBA15 and N,N-SBA15 may be related to the formation of outer-sphere surface complexes,while the adsorption of TC onto Fe-N,N-SBA15 was mainly attributed to the inner-sphere surface complexes.This study could offer potential materials that have excellent adsorption behavior for environmental remediation and suggested useful information for the preparing other adsorbents in environmental applications.     

Investigation of adsorption/desorption behavior of Cr(Ⅵ) at the presence of inorganic and organic substance in membrane capacitive deionization(MCDI)

The adsorption and desorption behavior of Cr(Ⅵ) in membrane capacitive deionization(MCDI) was investigated systematically in the presence of bovine serum albumin(BSA) and KCl with different concentrations, respectively. Results revealed that Cr(Ⅵ) absorption was enhanced and the adsorption amount for Cr(Ⅵ) increased from 155.7 to 190.8 mg/g when KCl concentration increased from 100 to 200 mg/L in the adsorption process, which was attributed to the stronger driving force. However, the adsorption amount sharply decreased to 90.2 mg/g when KCl concentration reached up to 1000 mg/L suggesting the negative effect for Cr(Ⅵ) removal that high KCl concentration had. As for the effect of BSA on ion adsorption, the amount for Cr(Ⅵ) significantly declined to 78.3 mg/g and p H was found to be an important factor contributing to this significant reduction. Then, the desorption performance was also conducted and it was obtained that the presence of KCl had negligible effect on Cr(Ⅵ) desorption, while promoted by the addition of BSA. The incomplete desorption was obtained and the residual chromium ions onto the electrode after desorption was detected via energy-dispersive X-ray spectroscopy(EDS). Based on above analysis, the enhanced removal mechanism for Cr(Ⅵ) in MCDI was found to be consisted of ion adsorption onto electrode surface, the redox reaction of Cr(Ⅵ) into Cr(III)and precipitation, which was demonstrated by X-ray photoelectron spectroscopy(XPS) and scanning electron microscope(SEM).     

Preparation and properties of chitosan–metal complex: Some factors influencing the adsorption capacity for dyes in aqueous solution

Chitosan–metal complexes have been widely studied in wastewater treatment, but there are still various factors in complex preparation which are collectively responsible for improving the adsorption capacity need to be further studied. Thus, this study investigates the factors affecting the adsorption ability of chitosan–metal complex adsorbents, including various kinds of metal centers, different metal salts and crosslinking degree. The results show that the chitosan–Fe( Ⅲ) complex prepared by sulfate salts exhibited the best adsorption efficiency(100%) for various dyes in very short time duration(10 min), and its maximum adsorption capacity achieved 349.22 mg/g. The anion of the metal salt which was used in preparation played an important role to enhance the adsorption ability of chitosan–metal complex. SO_4~(2-) ions not only had the effect of crosslinking through electrostatic interaction with amine group of chitosan polymer, but also could facilitate the chelation of metal ions with chitosan polymer during the synthesis process.Additionally, the p H sensitivity and the sensitivity of ionic environment for chitosan–metal complex were analyzed. We hope that these factors affecting the adsorption of the chitosan–metal complex can help not only in optimizing its use but also in designing new chitosan–metal based complexes.     

Composition analysis of colored dissolved organic matter in Taihu Lake based on three dimension excitation-emission fuorescence matrix and PARAFAC model, and the potential application in water quality monitoring

Taihu Lake is one of the five biggest lakes in China. Surface water samples from 26 sampling sites of Taihu Lake were collected. Furthermore wet chemical analysis (CODCr and BOD5) and measurement of three dimensional excitation-emission matrix (3DEEM) spectra in the laboratory have been conducted. Using parallel factor analysis (PARAFAC) model, three components of colored dissolved organic matter (CDOM) have been identified successfully, based on the analysis of 3DEEM data. The characteristics of the three components also have been described by comparing them to some components of CDOM, identified in earlier researches. Meanwhile, spatial variations of concentration for the three components in Taihu Lake have been analyzed, and the result indicates that the concentration of component 1 depends more on the situation of wastewater pollution and can be used as the indicator of wastewater pollution. The relationship between the concentrations of the three components and results of the wet chemical analysis show that none of the three components can be used as indicators of gross organic matter in water. However, the concentrations of all the three components have obvious linear relationships with the BOD5 value, especially for component 1 (r=0.72878). Finally, the potential applications of the composition analysis based on 3DEEM and PARAFAC model in water quality monitoring have been illuminated.     

Storage and sequestration of organic carbon in major paddy soils of China： Mechanism, stability and the impact on global change——A key project funded by the National Natural Science Foundation of China（2003-2005）

Chinapaddysoilsoccupyalandareaofabout3×107hm2andproduce44%oftotalcerealsofthestatewithalandportionof25%.Managementofpaddysoilscanbetracedbackto7000yearsB.P.andhaveledtoaparticularsoiltypeofanthropogenicwetlandsoilswithenhancedCstorageincomparisonwiththeu…     

Impacts of climatic change on water and natural hazards in the Alps: Can current water governance cope with future challenges? Examples from the European “ACQWA” project

This paper reviews the possible future situation of the Rhone River in the Swiss part of its catchment. Physical processes in the Alps govern the behaviour of the Rhone from its source (Rhone Glacier) to the Lake of Geneva, and substantial changes are expected to occur in the amount and seasonality of precipitation, and in the response of snow and glaciers to a warming climate. As a result, discharge in the alpine part of the Rhone River is likely to undergo an increase in winter and early spring, but strongly decreases from late spring to late autumn. These changes in water regimes will certainly be accompanied by more frequent geomorphic hazards, related to increases in heavy precipitation events and the melting of permanently frozen grounds. The direct and indirect impacts of a warming climate will affect key economic sectors such as tourism, hydropower, and agriculture, while shifts in extreme events will have an impact on the vulnerability of infrastructure and a range of economic sectors and services. Projections of the future course of events can help in advance planning and decision making in order to alleviate some of the more negative consequences of climate and hydrological impacts on key economic sectors in the region. This paper will thus discuss issues related to current and future water governance in the region, whether water-related policies are sufficiently robust today to cope with what may be rapid changes in water availability and water use in coming decades, and to resolve possible rivalries between economic sectors that may be increasingly confronted with problems of water availability at critical times of the year.