bluuebunny/crossref_metadata_2025 huggingface dataset:
Dynamic properties of sand from dry to fully saturated states
Authors: KUMAR J. , MADHUSUDHAN B.N.
Published: August 2011

By using bender and extender elements test, the velocities of the primary and shear waves, Vp and Vs respectively, were measured for a sandy material by gradually varying the degree of saturation, Sr, between the dry and fully saturated states. The effect on the results of varying the relative density and effective confining pressure was also studied. The measurements clearly reveal that for a certain optimum Sr, which is around 0·7–0·9% for the chosen sand, the value of the shear modulus G reaches a maximum value, whereas the corresponding Poisson's ratio ν attains a minimum value. The values of the shear modulus corresponding to Sr ≈ 0% and Sr = 100% tend towards the same value. For values of Skempton's B parameter greater than 0·99, the values of Vp and ν rise very sharply to those of water. The predictions from Biot's theory with respect to the variation of Vp with Sr match well with the measured experimental data.
Impact of sludge retention time on sludge characteristics and microbial community in MBR
Authors: Su Yuchun , Pan Jill Ruhsing , Huang Chihpin , Chang Chialing
Published: August 2011

In this study, the impact of sludge retention time (SRT) on sludge characteristics and microbial community and the effect on membrane fouling in membrane bioreactor (MBR) was investigated. The results show that MBR with longer SRT has less fouling propensity, in agreement with other studies, despite the fact that the MBR with longer SRT contained higher MLSS and smaller particle size. However, much more soluble microbial products (SMPs) were released in MBR with shorter SRT. More slime on the membrane surface was observed in MBR with shorter SRT while sludge cakes formed on the membrane surface in MBR with longer SRT. The results show that SMP contributes to the severe fouling observed in MBR with shorter SRT, which is in agreement with other studies showing that SMPs were the major foulants in MBR. Under different SRTs of operation, the bacterial community structures of the sludge obtained by use of polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) were almost identical, but those on the membrane surface differed substantially. It suggests that, although SRT has impact on sludge characteristics, it doesn't affect the microbial community in the suspension.
Integrated process control for recirculating cooling water treatment in the coal chemical industry
Authors: Pei Y. S. , Guo W. , Yang Z. F.
Published: August 2011

This work focused on the integrated process of the recirculating cooling water (RCW) treatment to achieve approximate zero emission in the coal chemical industry. The benefits of fractional and comprehensive RCW treatment were quantified and qualified by using a water and mass balance approach. Limits of cycle of concentrations and some encountered bottlenecks were used to ascertain set target limits for different water sources. Makeup water was mixed with water produced from reverse osmosis (RO) in the proportion of 6:4, which notably reduced salts discharge. Side infiltration, which settled down suspended solids, can reduce energy consumption by over 40%. An automated on-line monitoring organic phosphorus inhibitor feed maintains the RCW system stability in comparison to the manual feed. Two-step electrosorb technology (EST) instead of an acid feed can lead cycle of concentration of water to reach 7.0. The wastewater from RO, EST and filter was transferred into a concentration treatment system where metallic ions were adsorbed by permanent magnetic materials. Separation of water and salts was completed by using a magnetic disc separator. Applying the integrated process in a coal chemical industry, a benefit of 1.60 million Yuan annually in 2 years was gained and approximate zero emission was achieved. Moreover, both technical and economic feasibility were demonstrated in detail.
Enhanced biodegradation of 4-aminobenzenesulfonate in membrane bioreactor by Pannonibacter sp. W1
Authors: Zhang Jinsong , Wang Yanqing , Zhou Ji Ti , Wang Rong , Goh Shuwen , Fane Anthony G.
Published: August 2011

4-Aminobenzenesulfonate (4-ABS), an aromatic amine and recalcitrant toxic pollutant, is widely used in the dye and pharmaceutical industry. Pannonibacter sp. W1 is a specialized microbial strain which can efficiently degrade 4-ABS. This study shows the feasibility of using the specialized strain in an MBR system to treat synthetic wastewater containing large amount of 4-ABS. Due to membrane retention, the biomass concentration is able to reach 5 g/L within two months of continuous operation. Pannonibacter sp. W1 is able to adapt to the high loading rate of 1000 mg 4-ABS/L and achieve a remarkable 4-ABS removal efficiency of 99% within 6 h. Strain W1 grows well under the MBR continuous operation and remains as the dominant bacterium at the end of 60 days continuous operation. Minor membrane fouling has been detected within 40 days of operating at 15 LMH. At a flux of 25 LMH, the system experiences the ‘TMP jump’. The high organic removal rate and low membrane fouling results illustrate the excellent performance of the bioaugmented MBR system in 4-ABS wastewater treatment.
Performance of infiltration swales with regard to operation in winter times in an Alpine region
Authors: Fach Stefan , Engelhard Carolina , Wittke Nina , Rauch Wolfgang
Published: August 2011

In cold climate regions winter conditions significantly influence the performance of stormwater infiltration devices. Frozen soil and water storage by snow changes their operation. In this paper winter operation of a grassed infiltration swale was investigated using on-site and laboratory measurements. The field investigation of a grassed swale at a parking place in an Alpine region showed that the swale fulfilled its function properly. Although the top layer was frozen for some time, the storage capacity of the swale was sufficient to store the precipitation until the conditions improved. The soil attenuated the air temperature, at 20 cm below ground surface the soil was only frozen for one week. Winter maintenance proved to be a problem, together with the snow from the parking place a lot of gravel and fine particles were deposited at one end of the swale. This decreased the hydraulic conductivity at that point significantly. The laboratory tests with soil columns showed an increase of flow time through the soil column with decreasing soil moisture content. For soil temperatures below 0 °C the hydraulic conductivity was reduced for increasing initial soil moisture contents. All in all the hydraulic conductivity was best around 0 °C for all soil water contents. However, also at minus 5 °C the coefficient of hydraulic conductivity was always at least above 10−6 m/s, thus within the range of tolerated hydraulic conductivity specified in the national guidelines. Nevertheless, the handling of the soil was found to have high influence on the results. The results indicate that in the Alpine region infiltration swales operate sufficiently under winter conditions although with decreased performance.
Real-time control of sewer systems using turbidity measurements
Authors: Lacour C. , Schütze M.
Published: August 2011

Real-time control (RTC) of urban drainage systems has been proven useful as a means to reduce pollution by combined sewer overflow discharges. So far, RTC has been investigated mainly with a sole focus on water quantity aspects. However, as measurement techniques for pollution of wastewater are advancing, pollution-based RTC might be of increasing interest. For example, turbidity data sets from an extensive measurement programme in two Paris catchments allow a detailed investigation of the benefits of using pollution-based data for RTC. This paper exemplifies this, comparing pollution-based RTC with flow-based RTC. Results suggest that pollution-based RTC indeed has some potential, particularly when measurements of water-quality characteristics are readily available.
Climate change tendencies observable in the rainfall measurements since 1950 in the Federal Land of North Rhine-Westphalia and their consequences for urban hydrology
Authors: Einfalt Th. , Quirmbach M. , Langstädtler G. , Mehlig B.
Published: August 2011

Climate change is present in climatological models – but did we already observe changes in the past measurement data? For the state of North Rhine Westphalia, the rainfall measurements since 1950 have been systematically analysed in order to find out whether there have already been trends and whether the behaviour of rainfall has changed in time. More than 600 station series have been screened for use in the project and quality controlled. Implausible data were discarded. For the analysis, standard values such as yearly sums, half-yearly sums, monthly sums, number of dry days, number of days with precipitation above a threshold, partial time series and extreme values statistics have been calculated and evaluated. Results show that also in the past 50 years, changes in precipitation regime could be observed. These changes have been regionally different. Consequences for urban hydrology include a development of more flexible design approaches.
Effects on evaporation rates from different water-permeable pavement designs
Authors: Starke P. , Göbel P. , Coldewey W. G.
Published: August 2011

The urban water balance can be attenuated to the natural by water-permeable pavements (WPPs). Furthermore, WPPs have a 16% higher evaporation rate than impermeable pavements, which can lead to a better urban climate. Evaporation rates from pavements are influenced by the pavement surface and by the deeper layers. By a compared evaporation measurement between different WPP designs, the grain size distribution of the sub-base shows no influence on the evaporation rates in a significant way. On the contrary, a sub-base made of a twin-layer decreases the evaporation by 16% compared to a homogeneous sub-base. By a change in the colour of the paving stone, 19% higher evaporation rates could be achieved. A further comparison shows that the transpiration-effect of the grass in grass pavers increases the evaporation rates more than threefold to pervious concrete pavements. These high evapotranspiration rates can not be achieved with a pervious concrete paving stone. In spite of this, the broad field of application of the pervious concrete paving stone increases the importance in regard to the urban climate.
Improving collected rainwater quality in rural communities
Authors: Garrido S. , Aviles M. , Ramirez A. , Gonzalez A. , Montellano L. , Gonzalez B. , de la Paz J. , Ramirez R. M.
Published: August 2011

The country of Mexico is facing serious problems with water quality and supply for human use and consumption in rural communities, mainly due to topographic and isolation. In Mexico the average annual precipitation is 1,500 cubic kilometers of water, if 3% of that amount were used, 13 million Mexicans could be supplied with drinking water that they currently do not have access. Considering the limited infrastructure and management in rural communities, which do not receive services from the centralized systems of large cities, a modified pilot multi-stage filtration (MMSF) system was designed, developed, and evaluated for treating collected rainwater in three rural communities, Ajuchitlan and Villa Nicolas Zapata (Morelos State) and Xacxamayo (Puebla State). The efficiencies obtained in the treatment system were: colour and turbidity >93%. It is worth mentioning that the water obtained for human use and consumption complies with the Mexican Standard NOM-127-SSA1-1994.
Elaboration of the hydroxyapatite with different precursors and application for the retention of the lead
Authors: Meski S. , Ziani S. , Khireddine H. , Yataghane F. , Ferguene N.
Published: August 2011

Carbonate hydroxyapatite (CHAP) was synthesized from different precursors; synthetic (CaCO3 and Ca(OH)2) and natural (egg shell before and after calcinations at 900°C) under different conditions and characterized by using TG/DTG analysis, X-ray powder diffraction (XRD) method and Fourier transform infrared (FT-IR) spectroscopy techniques. The results of these analyses indicate that the four powders present the same structure of hydroxyapatite. Furthermore the four powders obtained were used for the retention of lead. The results obtained indicated that all powders present high adsorption capacity for lead, but from environmental and economic views, the hydroxyapatite synthesized from eggshell no calcined (HA2) is most advantageous. The influence of different sorption parameters, such as: initial metal concentration, equilibration time, solution pH and sorbent dosage was studied and discussed.
Calibration and verification of models of organic carbon removal kinetics in Aerated Submerged Fixed-Bed Biofilm Reactors (ASFBBR): a case study of wastewater from an oil-refinery
Authors: Trojanowicz Karol , Wójcik Włodzimierz
Published: August 2011

The article presents a case-study on the calibration and verification of mathematical models of organic carbon removal kinetics in biofilm. The chosen Harremöes and Wanner & Reichert models were calibrated with a set of model parameters obtained both during dedicated studies conducted at pilot- and lab-scales for petrochemical wastewater conditions and from the literature. Next, the models were successfully verified through studies carried out utilizing a pilot ASFBBR type bioreactor installed in an oil-refinery wastewater treatment plant. During verification the pilot biofilm reactor worked under varying surface organic loading rates (SOL), dissolved oxygen concentrations and temperatures. The verification proved that the models can be applied in practice to petrochemical wastewater treatment engineering for e.g. biofilm bioreactor dimensioning.
Anode and cathode materials characterization for a microbial fuel cell in half cell configuration
Authors: Pant Deepak , Van Bogaert Gilbert , Porto-Carrero Christof , Diels Ludo , Vanbroekhoven Karolien
Published: August 2011

Microbial fuel cells (MFCs) are novel bioelectrochemical devices for spontaneous conversion of biomass into electricity through the metabolic activity of the bacteria. Microbial production of electricity may become an important source of bioenergy in future because MFCs offer the possibility of extracting electric current from a wide range of soluble or dissolved complex organic wastes and renewable biomass. However, the materials used in these devices are still not economic and researchers use different materials as cathode and anode in MFCs. This results in variable performance which is difficult to compare. We tested several commercially available materials for their suitability as anode in an acetate fed MFC. Besides, a novel non-platinized activated carbon (AC) based, gas porous air cathode was also tested. Both the anode and cathode were tested in a half cell configuration. Carbon cloth, graphite cloth and dynamically stable anode (DSA) served as ideal anode material with carbon cloth and graphite mesh reaching the open circuit voltage (OCV) of acetate oxidation (−500 mV vs. Ag/AgCl). The effect of increasing concentration of acetate on anode OCV was also investigated and results showed that on increasing the acetate concentration from 10 mM to 40 mM has no adverse impact on the anodic activity towards electrochemical oxidation of acetate. The AC cathode showed stable current (−1.2 mA/cm2) over a period of 100 days.
Comparison of Fenton's oxidation and ozonation for removal of estrogens
Authors: Nakrst Jana , Bistan Mirjana , Tišler Tatjana , Zagorc-Končan Jana , Derco Jan , Gotvajn Andreja Žgajnar
Published: August 2011

This study compares efficiency of Fenton's oxidation and ozonation of 17β-estradiol (E2) and 17α-ethinylestradiol (EE2) as two possible processes for removal of estrogens from aqueous solutions. The effectiveness of Fenton's oxidative removal was studied at different ratios of reagents Fe2+:H2O2 (1:0.5; 1:10; 1:20; 1:33), where with some molar ratios up to 100% removal of E2 and EE2 was achieved in the first few minutes of reaction. The best molar ratio for E2 (17β-estradiol) removal was 1:33, while in the case of EE2 the most efficient one was 1:20 ratio. Ozonation was much faster, because complete removal of estrogens was achieved in 30 seconds (pH≈6), but the time of ozonation was extended up to 60 minutes trying to decompose formed by-products, expressing estrogenic activity, detected by YES (Yeast Estrogen Screening) assay. The obtained results showed that the removal efficiency of estrogens from waters should be assessed by a combination of chemical analyses and bioassay.
Pilot scale evaluation of SANI® process for sludge minimization and greenhouse gas reduction in saline sewage treatment
Authors: Lu Hui , Wu Di , Tang Daniel T. W. , Chen G. H. , van Loosdrecht Mark. C. M. , Ekama G.
Published: August 2011

This study reports on a pilot trial of the SANI® process (Sulfate reduction, Autotrophic denitrification and Nitrification Integrated process) in Hong Kong. A pilot-scale SANI plant treating saline sewage at 10 m3/day was scaled-up from a lab-scale system treating synthetic saline sewage. The plant consisted of a sulfate reduction up-flow sludge bed (SRUSB), an anoxic bioreactor (BAR1) for autotrophic denitrification utilizing dissolved sulfide produced by the SRUSB and an aerobic bioreactor (BAR2) for nitrification. The SANI® pilot plant was successfully operated for 225 days and achieved average COD, TSS, TN removal of 87, 87, and 57%, respectively. The ratio of MLVSS to MLSS in the SRUSB was stable at 0.7 and the average sludge volume index (SVI) was constantly below 110 ml/g. No sludge was purposely withdrawn from the plant during 225-day plant operation. This was attributed to a very low observed sludge yield (0.02 kgVSS/kgCOD removed) of the SRUSB reactor. DNA extraction, PCA amplification results revealed that no methanogens were detected in the SRUSB. SANI® can reduce 90% sludge production, 35% energy and 36% GHG compared to conventional biological nutrient removal (CBNR) process.
Overview of municipal sludge fluid bed incineration in North America – from green to greener – the Lakeview, the Duffin Creek and the Southerly experiences
Authors: Dangtran K. , Takmaz L. , Pham H. , Bergel J. Y. , Welp J. , Burrowes P.
Published: August 2011

Thermal processes used in sludge disposal have become more attractive as process improvements have been introduced, such as power generation and efficient heat recovery. More and more utilities and agencies are reevaluating their sludge management practices to ensure that they are providing sustainable management solutions for their clients. The thermal process design approach to the disposal of sludge is not only designed to achieve stricter emission limits but also is more energy efficient compared to its predecessors. Increasing numbers of new plants are being built every year with more energy efficient heat recovery features such as air preheating and cogeneration with steam and electricity production. This paper presents an overview of fluid bed incineration in North America and its evolution over the last decades. Case studies of the last three newest and largest plants in North America are presented, including the Lakeview Plant, Duffin Creek Plant, both in Ontario, Canada and the Southerly Plant in Cleveland, Ohio, USA.
Assessing the convergence of LHS Monte Carlo simulations of wastewater treatment models
Authors: Benedetti Lorenzo , Claeys Filip , Nopens Ingmar , Vanrolleghem Peter A.
Published: August 2011

Monte Carlo (MC) simulation appears to be the only currently adopted tool to estimate global sensitivities and uncertainties in wastewater treatment modelling. Such models are highly complex, dynamic and non-linear, requiring long computation times, especially in the scope of MC simulation, due to the large number of simulations usually required. However, no stopping rule to decide on the number of simulations required to achieve a given confidence in the MC simulation results has been adopted so far in the field. In this work, a pragmatic method is proposed to minimize the computation time by using a combination of several criteria. It makes no use of prior knowledge about the model, is very simple, intuitive and can be automated: all convenient features in engineering applications. A case study is used to show an application of the method, and the results indicate that the required number of simulations strongly depends on the model output(s) selected, and on the type and desired accuracy of the analysis conducted. Hence, no prior indication is available regarding the necessary number of MC simulations, but the proposed method is capable of dealing with these variations and stopping the calculations after convergence is reached.
Sources and leaching of manganese and iron in the Saigon River Basin, Vietnam
Authors: Van Ha Nguyen Thi , Takizawa Satoshi , Oguma Kumiko , Van Phuoc Nguyen
Published: August 2011

High concentrations of manganese and iron in the Saigon River are major problems for the water supply in Ho Chi Minh City (HCMC), Viet Nam. To identify their sources and leaching processes, we surveyed water quality along the Saigon River and ran batch leaching tests using soil and sediment samples. Two important leaching processes were identified: acidic leaching from acid sulfate soil (ASS) in the middle reaches of the river, and Mn dissolution and Fe reduction from sediments in the downstream reaches. Low pH caused the concurrent release of Fe and Mn from the ASS. In contrast, anoxia caused the release of Fe but not Mn from the sediments, whereas low pH facilitated Mn dissolution. Sediments are a more important source of Mn because of their higher Mn contents (10 times) and release rates (14 times) than those from ASS.
Simultaneous copper, cobalt and phenol removal from aqueous solutions by alternating biosorption and biodegradation
Authors: Tsekova K. , Ganeva S. , Hristov A. , Todorova D. , Beschkov V.
Published: August 2011

A strategy for removal of heavy metals and phenol from wastewaters is proposed. It involves consecutive cation biosorption by fungi, phenol biodegradation by the yeast association Candida sp. 2326 + Candida sp. 2327 and regeneration. Copper and cobalt removal from aqueous solutions containing 80–120 mg/L phenol by biosorption, using Rhizopus archizus cells immobilized onto poly(vinyl alcohol), was investigated by conducting a series of batch experiments. The removal efficiencies were 81% for Cu and 5% for Co. The residual concentrations of Cu (1.9 mg/L) and of Co (9.5 mg/L) did not change the biodegradation dynamics of phenol. A quantitative biodegradation of 120 mg/L phenol proceeded within 22 h. After biodegradation of phenol, the removal efficiencies achieved by biosorption after regeneration were 90% for Cu and 44% for Co. It was found that copper and cobalt form positively charged complexes with phenol. This complex formation hinders the retention of Cu and Co by the biosorbent and reduces the uptake of their cations.
The impact of cost recovery and sharing system on water policy implementation and human right to water: a case of Ileje, Tanzania
Authors: Kibassa Deusdedit
Published: August 2011

In Tanzania, the National Water Policy (NAWAPO) of 2002 clearly stipulates that access to water supply and sanitation is a right for every Tanzanian and that cost recovery is the foundation of sustainable service delivery. To meet these demands, water authorities have introduced cost recovery and a water sharing system. The overall objective of this study was to assess the impact of cost recovery and the sharing system on water policy implementation and human rights to water in four villages in the Ileje district. The specific objectives were: (1) to assess the impact of cost recovery and the sharing system on the availability of water to the poor, (2) to assess user willingness to pay for the services provided, (3) to assess community understanding on the issue of water as a human right, (4) to analyse the implications of the results in relation to policies on human rights to water and the effectiveness of the implementation of the national water policy at the grassroots, and (5) to establish the guidelines for water pricing in rural areas.

Questionnaires at water demand, water supply, ability and willingness to pay and revenue collection were the basis for data collection. While 36.7% of the population in the district had water supply coverage, more than 73,077 people of the total population of 115,996 still lacked access to clean and safe water and sanitation services in the Ileje district. The country's rural water supply coverage is 49%. Seventy-nine percent of the interviewees in all four villages said that water availability in litres per household per day had decreased mainly due to high water pricing which did not consider the income of villagers. On the other hand, more than 85% of the villagers were not satisfied with the amount they were paying because the services were still poor. On the issue of human rights to water, more than 92% of the villagers know about their right to water and want it exercised by the government.

In all four villages, more than 78% of the interviewees are willing to pay for water provided that the tariffs are affordable. Water policy implementation continues slowly: regardless of the fact that more than five years have passed since policy inception, 60% of the villagers in Itumba still have no water services at all. The study shows that government fulfilment of human rights to water has a long way to go, especially in rural areas where people cannot afford to pay for water and some of the villages still depend on water from wells and seasonal rivers.
Analysis of enterovirus and adenovirus presence in swimming pools in Cyprus from 2007–2008
Authors: Bashiardes S. , Koptides D. , Pavlidou S. , Richter J. , Stavrou N. , Kourtis C. , Papageorgiou G. T. , Christodoulou C. G.
Published: August 2011

An analysis was carried out to determine the presence of enteroviruses and adenoviruses in public swimming pools in Cyprus. The effectiveness of the commonly implemented disinfection procedure of chlorination was confirmed by determination of bacteriological markers. Analysis of viral presence was carried out by sampling random swimming pools from the five major cities in Cyprus during a period of 21 months spanning from April 2007 to December 2008. A 10 l sample was taken from each swimming pool to be tested and was subsequently concentrated via membrane filtration using a new methodological approach for virus elution. Concentrated samples were analysed using of a Real Time Polymerase Chain Reaction (PCR) TaqMan® probe based approach to detect the presence of enteroviruses and adenoviruses. Over the period of 21 months a total of 126 swimming pools were sampled and analysed. In four swimming pools enteroviruses were detected, in one pool echovirus 18 was identified, in two pools echovirus 30 was identified and in one other pool poliovirus Sabin 1 was identified. Similarly, in four swimming pools adenoviruses were detected, in all four adenovirus 41 was identified. Bacteriological marker analysis showed that 98% of pools complied with Cyprus regulations.
Seasonal factors influencing the failure of buried water reticulation pipes
Authors: Gould S. J. F. , Boulaire F. A. , Burn S. , Zhao X. L. , Kodikara J. K.
Published: August 2011

While the use of environmental factors in the analysis and prediction of failures of buried reticulation pipes in cold environments has been the focus of extensive work, the same cannot be said for failures occurring on pipes in other (non-freezing) environments. A novel analysis of pipe failures in such an environment is the subject of this paper. An exploratory statistical analysis was undertaken, identifying a peak in failure rates during mid to late summer. This peak was found to correspond to a peak in the rate of circumferential failures, whilst the rate of longitudinal failures remained constant. Investigation into the effect of climate on failure rates revealed that the peak in failure rates occurs due to differential soil movement as the result of shrinkage in expansive soils.
Catalytic wet air oxidation with Ni- and Fe-doped mixed oxides derived from hydrotalcites
Authors: Ovejero G. , Rodríguez A. , Vallet A. , Gómez P. , García J.
Published: August 2011

Catalytic wet air oxidation of Basic Yellow 11 (BY11), a basic dye, was studied in a batch reactor. Layered double hydroxides with the hydrotalcite-like structure containing nickel or iron cations have been prepared by coprecipitation and subsequently calcined leading to Ni- and Fe-doped mixed oxides, respectively. Compared with the results in the wet air oxidation of BY11, these catalysts showed high activity for total organic carbon (TOC), toxicity and dye removal at 120 °C and 50 bars after 120 min. It has been demonstrated that the activity depended strongly on the presence of catalyst. The results show that catalysts containing nickel provide a higher extent of oxidation of the dye whereas the reaction carried out with the iron catalyst is faster. The Ni and Fe dispersion determined from the TPR results was higher for the catalysts with a lower Ni or Fe content and decreased for higher Ni or Fe contents. On the basis of activity and selectivity, the Ni containing catalyst with the medium (3%) Ni content was found to be the best catalyst. Finally, a relationship between metal content of the catalyst and reaction rate has been established.
Nitrate removal using different carbon substrates in a laboratory model
Authors: Hashemi Seyyed Ebrahim , Heidarpour Manouchehr , Mostafazadeh-Fard Behrouz
Published: August 2011

Agricultural fields have been frequently identified as major contributors of nitrate leaching into surface and ground waters. Tile drains can act as direct pathways, transferring leached nitrate to surface water. Bioreactor filters are useful for the removal of nitrate from drainage waters; however, these filters require an external carbon supply to sustain denitrification. In this study, four organic carbon sources including wood, barley straw, rice husks, and date palm leaf, were used to enhance denitrification and the effects of water velocity and influent nitrate concentration on the nitrate removal were evaluated. Cumulative nitrate removal was highest for the date palm leaf treatments and was lowest for the wood treatments. The effects were in decreasing order for date palm leaf, barley straw, rice husks, and wood, respectively. The performance of the biofilters improved with increasing influent nitrate concentration and decreasing water velocity, allowing for high nitrate removal rates to be achieved. The results showed that all of the treatments had reduced the effluent nitrate concentrations below the USEPA maximum contaminant level for drinking water of 45 mg L−1 nitrate at the end of the study.
Enhancing the removal of arsenic, boron and heavy metals in subsurface flow constructed wetlands using different supporting media
Authors: Allende K. Lizama , Fletcher T. D. , Sun G.
Published: August 2011

The presence of arsenic and heavy metals in drinking water sources poses a serious health risk due to chronic toxicological effects. Constructed wetlands have the potential to remove arsenic and heavy metals, but little is known about pollutant removal efficiency and reliability of wetlands for this task. This lab-scale study investigated the use of vertical subsurface flow constructed wetlands for removing arsenic, boron, copper, zinc, iron and manganese from synthetic wastewater. Gravel, limestone, zeolite and cocopeat were employed as wetland media. Conventional gravel media only showed limited capability in removing arsenic, iron, copper and zinc; and it showed virtually no capability in removing manganese and boron. In contrast, alternative wetland media: cocopeat, zeolite and limestone, demonstrated significant efficiencies – in terms of percentage removal and mass rate per m3 of wetland volume – for removing arsenic, iron, manganese, copper and zinc; their ability to remove boron, in terms of mass removal rate, was also higher than that of the gravel media. The overall results demonstrated the potential of using vertical flow wetlands to remove arsenic and metals from contaminated water, having cocopeat, zeolite or limestone as supporting media.
Effect of sludge retention time on characteristics of dynamic membrane in sequencing bioreactors
Authors: Duan Wensong , Fu Dafang , Zhu Yawen , Xu Xiaoguang , Li Cheng
Published: August 2011

The characteristics of self-forming dynamic membrane (DM) in sequencing bioreactors under different sludge retention times (SRT) (SRT = 5, 10, 20, 40, 60 days) were studied using a scanning electron microscope, particle sizing distribution and others. The results indicated that the SRT has an evident effect on the characteristics of DM. The content of extracellular polymeric substances and protein decreased with the increase of SRT. The change of polysaccharide was small regardless of SRT. The filtration resistance of the DM was divided into two stages: an initial slowly-rising stage and a fast-rising later stage which were both irrespective of SRT. With the increase of SRT, the filtration resistance increase extent reduced and the running cycle became longer. Compared to the lower SRT, the particle size distribution of mixed liquor and DM has a decreasing trend at higher SRT. The average particle size of DM was larger than that of the mixed liquor irrespective of SRT. The amounts and types of microorganisms on the surface of DM were more abundant as SRT increased. Low SRT produced the DM surface with some Cocci while the high SRT gave the DM dominated with Cocci, Filamentous and Bacillus.
Addition of a magnetite layer onto a polysulfone water treatment membrane to enhance virus removal
Authors: Raciny I. , Zodrow K. R. , Li D. , Li Q. , Alvarez P. J. J.
Published: August 2011

The applicability of low-pressure membranes systems in distributed (point of use) water treatment is hindered by, among other things, their inability to remove potentially harmful viruses and ions via size exclusion. According to the USEPA and the Safe Drinking Water Act, drinking water treatment processes must be designed for 4-log virus removal. Batch experiments using magnetite nanoparticle (nano-Fe3O4) suspensions and water filtration experiments with polysulfone membranes coated with nano-Fe3O4 were conducted to assess the removal of a model virus (bacteriophage MS2). The membranes were coated via a simple filtration protocol. Unmodified membranes were a poor adsorbent for MS2 bacteriophage with less than 0.5-log removal, whereas membranes coated with magnetite nanoparticles exhibited a removal efficiency exceeding 99.99% (4-log). Thus, a cartridge of PSf membranes coated with nano-Fe3O4 particles could be used to remove viruses from water. Such membranes showed negligible iron leaching into the filtrate, thus obviating concern about coloured water. Further research is needed to reduce the loss of water flux caused by coating.
Phosphorus removal by laboratory-scale unvegetated vertical-flow constructed wetland systems using anthracite, steel slag and related blends as substrate
Authors: Wu Junmei , He Feng , Xu Dong , Wang Rong , Zhang Xiangling , Xiao Enrong , Wu Zhenbin
Published: August 2011

This research aimed to investigate the phosphorus (P) removal of a series of laboratory-scale unvegetated vertical-flow constructed wetland systems using anthracite, steel slag and related blends as substrate in treatment of low concentration domestic sewage. The long-term performance of P removal was firstly studied by using single substrate of anthracite or steel slag, and three systems applying various combined substrates were investigated when the average P loading rate varied between 0.9 and 1.5 g TP/m2·d. The results demonstrated that both anthracite and steel slag systems were highly effective in removing total P (TP, 77.17 ± 23.34% and 90.26 ± 4.48%) and soluble reactive P (SRP, 92.14 ± 12.56% and 96.20 ± 2.58%). The system filled with anthracite, vermiculite and steel slag from the top down removed 82.45 ± 9.52% and 87.83 ± 8.58% of TP and SRP, respectively. However, other combined substrate systems showed comparative low and fluctuant P removal. The effluent pH was maintained at 7–9, which met environmental requirements of China. Therefore, anthracite provides a long-term high efficiency of P removal and may be a promising substrate from the standpoint of the effluent pH, and the arrangement of combined substrate has a prominent effect on P removal.
A promising approach of reject water treatment using a tidal flow constructed wetland system employing alum sludge as main substrate
Authors: Yang Y. , Zhao Y. Q. , Wang S. P. , Guo X. C. , Ren Y. X. , Wang L. , Wang X. C.
Published: August 2011

This study examined a novel reuse of alum sludge, an inescapable by-product of drinking water treatment process when aluminium salt is added as a coagulant, as the main medium in a laboratory-scale multi-stage constructed wetland (CW) system for reject water treatment. Such reject water is a main concern in municipal wastewater treatment plant (MWWTP) for increasing the organic and nutrient loading. A ‘tidal flow’ strategy was employed to enhance the wetland aeration to stimulate organic matters (OM) and ammoniacal-nitrogen (N) oxidation while the ‘step feed’ operation was adopted to supply the necessary amount of carbon source for denitrification. The results reveal that alum sludge acting as P adsorbent can secure the P removal. Meanwhile, high removals of N and OM can also be obtained due to the active bacteria growth on the alum sludge surface. The results show that average removal efficiencies of 65.4 ± 12.3% for chemical oxygen demand (COD), 67.8 ± 9.2% for five-day biochemical oxygen demand (BOD5), 33.6 ± 17.0% for N and 99.5 ± 0.49% for P can be achieved over a period of 190 days. This indicates that novel reuse of alum sludge as medium in CW system can provide a promising approach for reject water treatment. Therefore, it will significantly reduce the amount of pollutant feedback through reject water recycling in a MWWTP.
Combination of batch experiments with continuous reactor data for ADM1 calibration: application to anaerobic digestion of pig slurry
Authors: Girault R. , Rousseau P. , Steyer J. P. , Bernet N. , Béline F.
Published: August 2011

Modelling anaerobic digestion processes is a key aspect of studying and optimizing digesters and related waste streams. However, for the satisfactory prediction of biogas production and effluent characteristics, some parameters have to be calibrated according to the characteristics of the substrates. This article describes a calibration procedure for the IWA ‘Anaerobic Digestion Model no. 1’ applied to the modelling of a digester for treatment of pig slurry. The most sensitive parameters were selected and calibrated combining results from a continuous digester and from batch trials run with the sludge sampled from the digester and the addition of specific substrates. According to the sensitivity analysis, acetoclastic methanogenesis, acetogenesis of propionate and acidogenesis of sugars were identified as the main sensitive steps in our case. The calibration procedure led us to modify slightly acetogenesis of propionate kinetic. However, acetoclastic methanogenesis and acidogenesis of sugars kinetics were significantly reduced by decreasing km and increasing Ks. Indeed, for instance, a decrease of km_ac from 8 to 7 day−1 combined with an increase of Ks_ac from 0.15 to 1.5 kgCOD/m3 was necessary. After calibration, ADM1 provides an accurate simulation of the continuous reactor results.
Removal of micropollutants and NOM in carbon nanotube-UF membrane system from seawater
Authors: Heo Jiyong , Joseph Lesley , Yoon Yeomin , Park Yong-Gyun , Her Namguk , Sohn Jinsik , Yoon Seong-Hoon
Published: August 2011

One of the main problems for seawater reverse osmosis desalination is membrane fouling associated with natural organic matter. Bisphenol-A (BPA) and 17α-ethinylestradiol (EE2) are well-known endocrine-disrupting compounds that have been detected in wastewater and seawater. In this study, the contribution of carbon nanotubes (CNTs, single-walled carbon nanotubes) to membrane fouling control and the potential adsorption mechanisms of BPA and EE2 were investigated using artificial seawater (ASW) in a bench scale ultrafiltration (UF) membrane coupled with CNTs. For high ionic strength ASW, UVA254 nm is a good alternative for highly aromatic dissolved organic carbon (DOC) determination, with a very strong linear relationship (R2 ≥ 0.99) with increasing DOC concentrations. Approximately 80% of DOC in ASW was rejected by the CNT-UF system where 31% of DOC was removed due to adsorption by CNTs. The presence of CNTs shows a 20% increase in membrane flux in ASW. A strong linear correlation between retention and adsorption of BPA and EE2 was obtained. The percentage of adsorption/retention of BPA and EE2 in UF-CNTs follows the order: 94.0/96.6 (DI + CNTs, EE2) > 86.2/90.0 (ASW + CNTs, EE2) > 73.6/78.9 (DI + CNTs, BPA) ≥ 74.1/77.3 (ASW + CNTs, BPA) > 29.8/29.8 (ASW, EE2) ≅ 27.3/27.3 (ASW, BPA) ≥ 25.3/25.3 (DI, EE2) ≅ 24.8/24.8 (DI, BPA). This indicates that retention by the UF-CNT system is mainly due to adsorption. Overall, EE2 adsorption was greater than BPA during the UF-CNT experiments, presumably due to the higher hydrophobicity of EE2 than BPA.
Effect of recirculation on organic matter removal in a hybrid constructed wetland system
Authors: Ayaz S. Ç. , Findik N. , Akça L. , Erdoğan N. , Kınacı C.
Published: August 2011

This research project aimed to determine the technologically feasible and applicable wastewater treatment systems which will be constructed to solve environmental problems caused by small communities in Turkey. Pilot-scale treatment of a small community's wastewater was performed over a period of more than 2 years in order to show applicability of these systems. The present study involves removal of organic matter and suspended solids in serially operated horizontal (HFCW) and vertical (VFCW) sub-surface flow constructed wetlands. The pilot-scale wetland was constructed downstream of anaerobic reactors at the campus of TUBITAK-MRC. Anaerobically pretreated wastewater was introduced into this hybrid two-stage sub-surface flow wetland system (TSCW). Wastewater was first introduced into the horizontal sub-surface flow system and then the vertical flow system before being discharged. Recirculation of the effluent was tested in the system. When the recirculation ratio was 100%, average removal efficiencies for TSCW were 91 ± 4% for COD, 83 ± 10% for BOD and 96 ± 3% for suspended solids with average effluent concentrations of 9 ± 5 mg/L COD, 6 ± 3 mg/L BOD and 1 mg/L for suspended solids. Comparing non-recirculation and recirculation periods, the lowest effluent concentrations were obtained with a 100% recirculation ratio. The effluent concentrations met the Turkish regulations for discharge limits of COD, BOD and TSS in each case. The study showed that a hybrid constructed wetland system with recirculation is a very effective method of obtaining very low effluent organic matter and suspended solids concentrations downstream of anaerobic pretreatment of domestic wastewaters in small communities.
Development of polymer lab-on-a-chip (LOC) for oxidation-reduction potential (ORP) measurement
Authors: Jang A. , Lee K. K. , Bishop P. L. , Kim I. S. , Ahn C. H.
Published: August 2011

Reverse osmosis (RO) desalination has been recognized as a promising method to solve the water shortage problem. Nevertheless, since it is energy intensive and has many problems associated with biofouling/fouling of RO membranes in RO plants, its commercial acceptance is still slow. Especially, as high levels of oxidizing agents negatively affect RO membrane efficiency and life span. So, there is a need to develop sensitive, selective, portable and rapid methods to determine oxidation-reduction potential (ORP) in feed solution. For developing a polymer ORP lab-on-a- chip (LOC), a microchannel patterned on a polymer substrate was successfully filled with 800 nm diameter silica beads using self-assembly bead packing technology. The measured ORPs using the three kinds of redox potential solutions were typically slightly lower than those of the nominal redox potential. But, all of the measurements should be deemed acceptable. The ORP LOC has also a much shorter response time than the conventional potentiometric sensor.
China's ChangingGuanxiCapitalism: Private Entrepreneurs between Leninist Control and Relentless Accumulation
Authors: McNally Christopher A.
Published: August 2011

Guanxiandguanxicapitalism are much-debated terms in the context of China's evolving political economy. This article explores the changing nature of China'sguanxicapitalism. It analyzes first various aspects ofguanxicapitalism, a unique conceptual blend infused with seemingly incongruous cultural and historical meanings drawn from both Chinese and Western roots. It then introduces three case studies of private firms, illustrating empirically how Chinese entrepreneurs' relationship with the political system is evolving. The article ends by assessing the ways in which political factors,guanxipractices and capitalist accumulation are interacting and changing. I hold thatguanxicapitalism is playing a crucial role in realigning the interests of state and capital in China. It yields idiosyncratic benefits to certain Chinese private firms, while also bridging the logics of freewheeling capital accumulation and authoritarian control in a state-dominated economy. In this view,guanxicapitalism encompasses both contradictory and complementary institutional logics. Since the persistence of Leninist control generates “deliberate ambiguity” in how China's private sector is governed, the penetration ofguanxinetworks into government-business relations creates institutional space that enables both Leninist control and relentless capital accumulation to proceed, in turn lending China's emergent capitalism a unique quality.
Explaining Regulatory Preferences: CSR, Soft Law, or Hard Law? Insights from a Survey of Nordic Pioneers in CSR
Authors: Gjølberg Maria
Published: August 2011

Business is often assumed to resist increased social and environmental regulation, preferring voluntary or soft-law approaches to global governance. This article analyzes the dynamics between CSR, soft law, and hard law by exploring corporate attitudes in the Nordic area towards CSR and regulation'an area reputed to be a forerunner in both CSR and social and environmental regulation. The analysis, based on a survey of the Nordic companies with the strongest CSR performance, reveals skepticism towards relying on CSR and voluntary approaches, combined with a very strong preference for increased international regulation of social and environmental issues. Drawing on insights from recent analyses in the governance literature, the article discusses the conditions under which business favors increased social and environmental regulation, concluding that corporate self-interest and increased international regulation can indeed coincide.