Showing papers in "Water Science & Technology: Water Supply in 2016"

Prediction of side weir discharge coefficient by support vector machine technique

Abstract: Side weirs have many possible applications in the field of hydraulic engineering. They are also considered an important structure in hydro systems. In this study, the support vector machine (SVM) technique was employed to predict the side weir discharge coefficient. The performance of SVM was compared with other types of soft computing techniques such as artificial neural networks (ANN) and adaptive neuro fuzzy inference systems (ANFIS). While ANN and ANFIS models provided a good prediction performance, the SVM model with a radial basis function kernel function outperforms them. The best SVM model was developed with a gamma coefficient and epsilon of 15 and 0.3, respectively. The SVM yielded a coefficient of determination ( R 2 ) equal to 0.96 and 0.93 for the training and testing data. Sensitivity analyses of the ANN, ANFIS and SVM models showed that the Froude number and ratio of weir length to the flow depth upstream of the weir are the most effective parameters for the prediction of the discharge coefficient.

Water pricing and irrigation across Europe: opportunities and constraints for adopting irrigation scheduling decision support systems

Abstract: Despite the plethora of irrigation scheduling decision support systems that have been developed over the past decades, there is little evidence of widespread adoption by farmers. This paper investigates the structural, institutional and political rigidities that affect the adoption of irrigation scheduling technologies in southern European countries and highlights the corresponding opportunities. The recent implementation of water pricing policies, as required under the European Water Framework Directive, could motivate farmers to invest in technologies for improving water management. A review of irrigation water prices in southern Europe found a large range of prices both within and between countries, from 0.054–0.645 €/m 3 (Greece) to 0.23–1.50 €/m 3 (France). However, inadequate monitoring infrastructure and a lack of political will to impose the new water prices are giving a mixed signal to farmers. An ageing and poorly trained farm population, small farm size and low level of farm investment also impede the uptake of irrigation technologies. Within this context, European-funded research needs to consider these constraints and pay closer attention to the conversion of knowledge and innovation into successful commercial products.

A systematic approach for the assessment of bacterial growth-controlling factors linked to biological stability of drinking water in distribution systems

Abstract: A systematic approach is presented for the assessment of (i) bacterial growth-controlling factors in drinking water and (ii) the impact of distribution conditions on the extent of bacterial growth in full-scale distribution systems. The approach combines (i) quantification of changes in autochthonous bacterial cell concentrations in full-scale distribution systems with (ii) laboratory-scale batch bacterial growth potential tests of drinking water samples under defined conditions. The growth potential tests were done by direct incubation of water samples, without modification of the original bacterial flora, and with flow cytometric quantification of bacterial growth. This method was shown to be reproducible (ca. 4% relative standard deviation) and sensitive (detection of bacterial growth down to 5 µg L−1 of added assimilable organic carbon). The principle of step-wise assessment of bacterial growth-controlling factors was demonstrated on bottled water, shown to be primarily carbon limited at 133 (±18) × 103 cells mL−1 and secondarily limited by inorganic nutrients at 5,500 (±1,700) × 103 cells mL−1. Analysis of the effluent of a Dutch full-scale drinking water treatment plant showed (1) bacterial growth inhibition as a result of end-point chlorination, (2) organic carbon limitation at 192 (±72) × 103 cells mL−1 and (3) inorganic nutrient limitation at 375 (±31) × 103 cells mL−1. Significantly lower net bacterial growth was measured in the corresponding full-scale distribution system (176 (±25) × 103 cells mL−1) than in the laboratory-scale growth potential test of the same water (294 (±35) × 103 cells mL−1), highlighting the influence of distribution on bacterial growth. The systematic approach described herein provides quantitative information on the effect of drinking water properties and distribution system conditions on biological stability, which can assist water utilities in decision-making on treatment or distribution system improvements to better control bacterial growth during water distribution.

Antibiotics in groundwater under locations with high livestock density in Germany

Abstract: Antibiotics are deployed in large quantities both in human and in veterinary medicine. Studies show that antibiotic residues occur in the environment (e.g. soil and surface waters). In some cases they were also detected in ground and drinking water. However, the degree of groundwater pollution by antibiotic residues from livestock farming is unknown. Therefore, the federal environment agency (UBA) supported a project that aimed to investigate near-surface groundwater samples in regions of high livestock density and high risk of groundwater exposure to antibiotics. By applying worst case criteria on existing sampling sites of our groundwater monitoring grid (high amounts of manure on site, high precipitation, low adsorption capacity of soils, high nitrate concentrations in ground water, etc.) adequate sampling sites were identified as well as relevant antibiotics (amount of application, water solubility, biological stability, etc.) by a literature review and contacts to local veterinary authorities. In total, groundwater at 48 sampling sites was selected for analyses of 23 antibiotic substances. Out of the 23 antibiotics, only three sulfonamides could be detected and quantified. With regard to the 48 sampling sites, at 39 locations no veterinary antibiotics were detected. At seven locations sulfadimidine and/or sulfadiazine was detected at low concentrations (

Linking discolouration modelling and biofilm behaviour within drinking water distribution systems

Abstract: High quality drinking water exits modern treatment works, yet water quality degradation such as discolouration continues to occur within drinking water distribution systems (DWDS). Discolouration is observed globally, suggesting a common process despite variations in source, treatment, disinfection and network configurations. The primary cause of discolouration has been identified as mobilisation of particulate material from pipe walls and the verified Prediction of Discolouration in Distribution Systems (PODDS) model uses measurable network hydraulics to simulate this response. In this paper the cohesive properties of discolouration material are explored and it is hypothesised that in simulating the turbidity response, the PODDS model is actually describing the development and cohesive strength behaviour of biofilms. Applying this concept can therefore facilitate a rapid and simple assessment of DWDS biofilm activity. A review of the findings from PODDS studies conducted internationally is presented, focussing on the macro or observable aspects of discolouration. These are compared and contrasted with associated biofilm studies which consider discolouration material at the micro-scale. Combining the results from these (past) studies to improve the understanding of interactions between microbial ecology and discolouration are discussed with a view to DWDS operational strategies that safeguard and optimise drinking water supply.

Evolution of rainwater harvesting and use in Crete, Hellas, through the millennia

Abstract: The low water availability in several regions of southeastern Hellas and particularly in several islands, such as Crete, has resulted in the construction of various types of water reservoir for collection and storage of rainwater, since their very early habitation. Since then, technologies for the construction and use of several types of cisterns have been developed. In Crete during the Minoan era, water cisterns were very well practiced as a basic means for water supply in several settlements. The Minoan water cistern technologies were further developed, mainly by enlargement of the scale of water systems, at subsequent stages of the Hellenic civilizations. Furthermore, more advanced water cistern technologies were invented, with a peak during the Hellenistic period which followed Alexander the Great, during which time they spread over a geographical area from Hellas to the west and to the east. The Romans inherited the cistern technologies and further developed them mainly by changing their application scale from small to large. Characteristic paradigms of Cretan cisterns are considered which justify the significance of that technology for water supply in areas with low water availability during the whole Cretan history. Herein, nowadays climatic conditions and water resources management in Crete are presented and discussed.

A systematic review of outcomes and lessons learned from general, rural, and country-specific Water Safety Plan implementations

Abstract: Water Safety Plans (WSPs) are a comprehensive risk assessment and management approach to water delivery that were internationally recommended in 2004 WSPs consist of five implementation steps, followed by evaluation To date, approximately 90 countries have implemented WSPs, however widespread uptake is limited by lack of documented outcomes and impacts We conducted a systematic review to collate outcomes, impacts, and lessons learned from WSPs developed in general, rural, and three case-study country contexts Overall, 53 documents met inclusion criteria In general contexts, the need for institutional support during WSP implementation was highlighted In rural applications, the need to simplify the WSP process and provide community support was emphasized In case study countries, we found the WSP process was selectively adapted and integrated within existing programs In outcome and impact evaluations, financial outcomes have the clearest evidence base, while operational outcomes are documented most frequently, particularly in relation to infrastructure improvements However, evidence is lacking on institutional and policy outcomes and impacts of WSPs To ensure WSPs reach their potential for improving water delivery and management, support should be provided to implementers, outcomes and impacts of urban, peri-urban, and rural WSP implementations should be evaluated, and adaptation of WSPs locally encouraged

Desalination leaders in the global market – current trends and future perspectives

Abstract: Since the world9s first land-based desalination plant was established in Australia in 1903, brackish groundwater and seawater desalination became a common water supply technology in many countries around the world. Desalination has proven as a reliable technology in times of drought and/or water scarcity, while in some countries it is an indispensable water supply source on a regular basis. This paper compares and evaluates major desalination leaders in the world (USA, Saudi Arabia, Israel, Australia, and China) with the aim of pointing out similarities and differences that made each of them successful. It also depicts a comprehensive picture of developments, trends and experiences in desalination at the global scale. Establishing desalination plants and ensuring their successful operation is a complex and multifaceted process dependent on capital and operational costs, production capacity, water salinity, geographical location, socio-economic and environmental conditions, and many other factors. The country specific comparison presented in this paper emphasizes the importance of regional planning for successful and sustainable desalination processes in the long term.

Distribution of microbial activity and specific microorganisms across sediment size fractions and pipe wall biofilm in a drinking water distribution system

Abstract: The aim of our study was to identify the dominant environmental niche (pipe wall and different sediment size fractions) in the distribution system for biological activity, Aeromonas and the occurrence of several microbial groups or specific opportunistic pathogens. The pipe wall and sediment fractions of three locations in a distribution system were sampled and different microbiological parameters were determined. The results demonstrated that most of the active biomass in the distribution system is located in the pipe wall biofilm and the smallest sediment size fraction. Fungi were more dominantly present in the pipe wall biofilm than in the sediment, whereas Aeromonas spp. has its dominant niche in the sediment. The highest numbers of the opportunistic pathogens Pseudomonas aeruginosa and Aspergillus fumigatus were observed in the biofilm. In contrast, Stenotrophomonas maltophilia was only observed in the sediment. The results from our study demonstrate that: (i) microbial activity in the distribution system is high on the pipe wall and sediment and (ii) different microbial groups or microbial species have different dominant environmental niches in the distribution system.

Community-based rainwater harvesting (CB-RWH) to supply drinking water in developing countries: lessons learned from case studies in Africa and Asia

Abstract: This paper uses pragmatic findings and lessons learned from three case studies to deduce that community-based rainwater harvesting (CB-RWH) is an innovative solution to develop sustainable drinking water supply systems in developing countries, especially in Africa and Asia. Taking advantage of traditional community-based activities in African and Asian villages, the water supply system can be significantly improved with the introduction and implementation of CB-RWH systems. Furthermore, sustainable, safe water sources in Africa and Asia can be brought to fruition when transparent self-regulatory management systems are supported through comprehensive design and maintenance guidelines and funded from private and public sources. To this end, the potential for CB-RWH to lead toward greater resilience and sustainability was investigated. Based on case studies of three successful demonstration projects in Africa and Asia, this paper identifies 14 innovative solutions resolving technical, economic, and social problems which have been barriers preventing the wide implementation of CB-RWH in developing countries, especially in Africa and Asia. It also recommends strategies to promote CB-RWH in African and Asian villages, which include the following: implementation of more pilot projects at local levels; promotion of and education in rainwater preservation and harvesting at all levels of the education system; and innovation in micro-funding systems in cooperation with corporate social responsibility activities. These strategies will promote the implementation of CB-RWH as a mainstream and high-priority technique for national, regional, and global water strategies.

Assessment of groundwater quality in the Seraidi region (north-east of Algeria) using NSF-WQI

Abstract: Scarcity of water, pollution load, political issues and rising population have drawn great attention for proper management of water resources such as groundwater in the 21st century. The evaluation of groundwater quality is a critical element in the assessment of water resources. The quality/potability of water that is consumed defines the baseline of protection against many diseases and infections. The present study aims to calculate the water quality index (WQI) by the analysis of seven physico-chemical parameters according to the National Sanitation Foundation (NSF) to assess the suitability of water for drinking, irrigation purposes and other human uses. In the present investigation, ten groundwater samples were collected from various parts of Seraidi municipality area located in the north-east of Algeria, Physico-chemical parameters such as pH, temperature, dissolved oxygen, phosphates, nitrates, turbidity and fecal coliforms were analyzed. The overall WQI values for all the samples were found to be in the range of 68–86, which reveals the fact that the quality of all the samples is only medium to good and could be used for drinking and other domestic uses only after proper treatment.

Optimization of total trihalomethanes' (TTHMs) and their precursors' removal by granulated activated carbon (GAC) and sand dual media by response surface methodology (RSM)

Abstract: A response surface methodology (RSM) applying central composite design with rotatable full factorial (14 non-center and six center points) was used to discern the effect of granular activated carbon (GAC), sand and pH on total trihalomethanes (TTHMs) and humic acid (HA) removal from drinking water. Results showed efficient TTHMs and HA removal by GAC while a sand column showed little effect for TTHMs but was significant for total organic carbon (TOC) removal. With GAC and a sand column of 4 cm, a pH increase from 6 to 8 caused an increase in TTHM removal from 79.8 to 83.6% while a decrease in HA removal from 26.6 to 6.6% was observed. An increase in GAC column depth from 10 to 20 cm caused a slight increase in TTHM removal from 99.4 to 99.7%, while TOC removal was increased from an average of 38.85% to 57.4% removal. The developed quadratic model for TTHM removal ( p = 0.048) and linear model for TOC removal ( p = 0.039) were significant. GAC column depth ( p < 0.0117) and column depth2 ( p < 0.039) were the most significant factors. A 98% TTHMs, 30%TOC and 51% residual chlorine removal were optimized at 9 cm GAC and 4 cm sand column depth at pH 8 with desirability factor ( D ) 0.64.

How can drinking water treatments influence chlorine dioxide consumption and by-product formation in final disinfection?

Abstract: In this study water samples of different origins (subalpine lake, artificial lake and river) were treated by pre-oxidation, coagulation/flocculation, adsorption on granular activated carbon and disinfection. Different laboratory-scale tests were carried out to evaluate the treatment impact on ClO2 consumption in disinfection and on the formation of disinfection by-products (trihalomethanes, adsorbable organic halogen, chlorite and chlorate). The results showed that coagulation/flocculation and activated carbon adsorption have the most significant impact on reducing disinfectant consumption. Pre-oxidation of artificial lake water with KMnO4 and NaClO determines the highest ClO2 consumption. Regardless of the water source, the amount of chlorite produced after disinfection with ClO2 is 40–60% lower using NaClO as the pre-oxidant rather than KMnO4 or ClO2. Otherwise, NaClO leads to a high formation of adsorbable organic halogens and trihalomethanes in artificial lake water (up to 60 μg/L and 20 μg/L respectively), while in the case of ClO2 oxidation, trihalomethane formation is 98% less compared to NaClO. Further, adding ferrous ion in coagulation/flocculation improves the removal of chlorite produced during pre-oxidation, with a 90% removal, mainly due to the reduction of chlorite to chloride. Finally, activated carbon adsorption after pre-oxidation and coagulation/flocculation removes adsorbable organic halogens and trihalomethanes respectively by 50–60% and 30–98%, and completes the chlorite and chlorate removal.

Competitive mechanism of ammonia, iron and manganese for dissolved oxygen using pilot-scale biofilter at different dissolved oxygen concentrations

Abstract: In this study, the competitive mechanism of ammonia, iron and manganese for dissolved oxygen (DO) in a biofilter was investigated, and a new start-up method of biofilter for ammonia, iron and manganese removal was approved, which can effectively shorten the start-up period from 3 ∼ 4 months to 51 days. The results demonstrated that when DO was sufficient (about 8 mg · L−1), ammonia, iron and manganese could be completely removed. When DO decreased from 6.5 to 4 mg · L−1, the concentration of ammonia in effluent was increased accordingly, though iron and manganese were removed efficiently. When DO was as low as 3 mg · L−1, only iron was removed, whereas most of ammonia and manganese still existed in the effluent. In addition, the oxidizing rates of the pollutants were not affected significantly with DO decrease. Turbidity removal in the biofilter was also investigated, and the results demonstrated that the turbidity was decreased to lower than 0.5 NTU in depth 0.4 m of the filter.

Satellite analysis to identify changes and drivers of CyanoHABs dynamics in Lake Taihu

Abstract: A long-term satellite-based analysis was performed to assess the impact of environmental factors and human efforts on cyanobacterial harmful blooms (CyanoHABs) dynamics in a typical shallow lake, Lake Taihu. A sub-pixel approach (algae pixel-growing algorithm) was used with 13 years of MOderate-resolution Imaging Spectroradiometer (MODIS) data to evaluate changes in bloom extension, initiation date, duration, and occurrence frequency before and after a massive bloom event (2007). Results indicated that the conditions after this event changed, with a general delay in bloom initiation and a reduction in bloom duration. The environmental drivers of daily, monthly and inter-annual CyanoHABs dynamics were analyzed by detrended correspondence analysis, principal components analysis and redundancy analysis. It demonstrated that wind speed was the main driver for daily CyanoHABs dynamics, and CODmn, TP and water temperature were closely related to monthly CyanoHABs dynamics. For the year scale, Tmean and nutrients were the main drivers of CyanoHABs initiation date and duration, and meteorological factors influenced CyanoHABs frequency for the whole lake. Regular monitoring of CyanoHABs by remote sensing is a key element in the continued assessment of bloom conditions in Lake Taihu, and nutrient reduction policies contribute to decrease CyanoHABs occurrence.

Evaluation of nitrate and perchlorate reduction using sulfur-based autotrophic and mixotrophic denitrifying processes

Abstract: The biological reduction of nitrate and perchlorate was comparatively evaluated in autotrophic and mixotrophic bioreactors using elemental sulfur and/or methanol as the energy source. The mixotrophic reactor was supplemented with methanol at CH3OH/NO3−-N ratio of 1 or 1.4. The mixotrophic reactor completely reduced perchlorate in the feed up to 1,000 μg l−1. The autotrophic reactor also showed high perchlorate reduction performance and decreased perchlorate from 1,000 μg l−1 to around 33 μg l−1. Complete reduction of 25 mg NO3−-N l−1 was achieved in both reactors, corresponding to a maximum nitrate reduction rate of 300 mg NO3−-N l−1d−1 and 400 mg NO3−-N l−1d−1 in the autotrophic and mixotrophic processes, respectively. Autotrophic denitrification caused an increase of effluent sulfate concentration, which may exceed the drinking water guideline value of 250 mg l−1. In the mixotrophic denitrification process, the effluent sulfate concentration was controlled by adjusting the C/N ratio in the influent. Mixotrophic denitrification was stimulated by 25 mg l−1 methanol addition and 53% of influent nitrate was reduced by the heterotrophic process, which decreased the effluent sulfate concentration to half of the autotrophic counterpart. Therefore, the mixotrophic process may be preferred over the autotrophic process when effluent sulfate concentration is of concern and a higher perchlorate reduction efficiency is desired.

Grafted cellulose acetate reverse osmosis membrane using 2-acrylamido-2-methylpropanesulfonic acid for water desalination

Abstract: Reverse osmosis (RO) membranes based on cellulose acetate (CA), were prepared using a phase inversion technique. To improve the hydrophilicity, salt rejection and water flux of these membranes, a novel grafting of 2-acrylamido-2-methylpropanesulfonic acid (AMPSA) was added on the top surface of the CA-RO membranes. The grafted CA-RO membranes were characterized by Fourier transform infrared spectroscopy (FTIR), contact angle, and scanning electron microscopy techniques. It was found that the contact angles were 58° and 45° for pristine CA and 15 wt% grafted CA-RO membranes, respectively, which suggest an increase in the membrane surface hydrophilicity after grafting. The morphological studies of the surface of the pristine CA-RO membrane revealed a typical ridge-and-valley morphology and displayed a relatively high surface roughness of 337 nm, and a significant decrease at 15 wt% of grafted CA-RO membrane to 7 nm. The effect of the grafting percentages of AMPSA on the water flux and salt rejection was studied using a cross flow RO unit . The salt rejection and water flux of the grafted CA-RO membrane with 15 wt% were 99.03% and 6 L/m2h, respectively.

Removal of iron and manganese from aqueous solutions using carbon nanotube filters

Abstract: Carbon nanotubes (CNTs) have become the focus of attention of many scientists and companies worldwide. CNT-based filters have a prospective advantage in comparison to the commercial filters already in operation because they are light weight and do not require electricity to operate. This investigation handles the filtration efficiency of manganese and iron from aqueous solution using commercial multiwalled carbon nanotubes (MWCNTs) (Taunit). The effects of different parameters such as CNT filter mass, concentration of manganese and iron in aqueous solution and pH of aqueous solution on removal of these heavy metals are determined. From these investigations, the removal efficiency of manganese and iron could reach 71.5% and 52% respectively for concentration 50 ppm, suggesting that Taunit is an excellent adsorbent for manganese and iron removal from water. There was a significant increase in removal efficiency at pH = 3 for manganese and pH = 8 for iron. The effect of oxidation on the structural of MWCNTs was characterized by scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) techniques to investigate the functionalization with oxygen-containing and outer diameter distribution. It was found that functionalized CNT-based filters are more efficient at removing manganese and iron from aqueous solutions. Oxidized MWCNTs may be a promising candidate for heavy metal ion removal from industrial wastewater.

Impact of irrigation water scarcity on rural household food security and income in Pakistan

Abstract: As Pakistan is currently facing a severe shortage of irrigation water, this paper analyzes the determinants of water scarcity and its impact on the yield of cereal crops (wheat, maize and rice), household income, food security and poverty levels by employing the propensity-score-matching approach. This study is based on a comprehensive set of cross-sectional data collected from 950 farmers from all four major provinces in Pakistan. The empirical analysis indicated that farmers with a water-scarcity problem have lower yield and household income, and are food insecure. Poverty levels were higher: in the range of 7–12% for a household facing a water-scarcity problem. The policy implications of the study are that the public and private sector in Pakistan needs to invest in irrigation water management to maintain the productivity of cereal crops which is important for household food security and poverty reduction.

Application of machine learning techniques to predict anomalies in water supply networks

Abstract: Methods to improve the operational efficiency of a water supply network by early detection of anomalies are investigated by making use of the data streams from multiple sensor locations within the network. The water supply network is a demonstration site of Vitens, a Dutch water company that has several district metering areas where flow, pressure, electrical conductance and temperature are measured and logged online. Three different machine learning approaches are tested for their feasibility to detect anomalies. In the first approach day-dependent support vector regression (SVR) models are trained for predicting the measurement signals and compared to straightforward models using mean and median estimates, respectively. Using SVRs or the averaged data as real-time pattern recognizers on all available signals, large leakages can be detected. The second approach utilizes adaptive orthogonal projections and reports an event when the number of hidden variables required to describe the streaming data to a user-defined degree (energy level threshold) increases. As a third approach, (unsupervised) clustering techniques are applied to detect anomalies and underlying patterns from the raw data streams. Preliminary results indicate that the current data set is too limited in the amount of events and patterns to harness the potential of these techniques.

Transport and deposition of suspended particles in saturated porous media: effect of hydrodynamic forces and pore structure

Abstract: In order to investigate the effects of pore structure and hydrodynamic forces on the particle transport and deposition, an experimental study on the transport and deposition of suspended particles (SP) in saturated porous medium (quartz sand and glass beads) was conducted under five different flow velocities at room temperature (22–25 °C). Silt particles with a mode of 10.7 μm diameter and fluorescein (as the dissolved tracer (DT)) were injected into the columns in short pulses. The SP transfer parameters were compared to the DT one. All the parameters (dispersivity, recovery rate, and deposition rate) obtained from the breakthrough data varied with the flow rate. The breakthrough curves were well described by an analytical solution of the advective–dispersive equation with a first-order deposition kinetic. The results showed that the transport of the SP was faster than the DT when the flow velocity reached a critical value which was different between glass beads and quartz sand was observed. The mean diameter of the recovered particles and the longitudinal dispersivity increase with flow rate; In addition, the recovery rate of SP is higher in the glass beads than that in the quartz sand even if under similar porosities. This study highlights the significance of pore structure and hydrodynamic forces in transport and deposition processes of SP.

Boron removal from brackish water by reverse osmosis and nanofiltration membranes: application of Spiegler–Kedem model and optimization

Abstract: Drinking water should contain certain chemicals only in limited quantities. Boron, one of these chemicals which is considered as a threatening compound and difficult to eliminate it from water. The purpose of the research is to study the major role of reverse osmosis (RO) and nanofiltration (NF) process which can contribute to the removal of this inorganic element from brackish water. For this reason, two RO and two NF membranes have been used to reduce boron and total salinity of brackish water. And since boron is a problematic compound, its elimination would not be easy too. To optimize these removal rates, two solutions based on the change of the chemical state of boron in water, either by varying the pH solution or by a complexation reaction, have been proposed in this work. Obtained results show that for both solutions, the boron removal percents have clearly improved and reached 95% for the first case and 70% for the second. It is worth noting that the Spiegler–Kedem model was applied to fit the found experimental results.

Uncertainty quantification of pressure-driven analysis for water distribution network modeling

Abstract: The hydraulic analysis of water distribution networks (WDNs) is divided into two approaches: namely, a demand-driven analysis (DDA) and a pressure-driven analysis (PDA). In the DDA, the basic assumption is that the nodal demand is fully supplied irrespective of the nodal pressure, which is mainly suitable for normal operating conditions. However, in abnormal conditions, such as pipe failures or unexpected increase in demand, the DDA approach may cause unrealistic results, such as negative pressure. To address the shortcomings of DDA, PDA has been considered in a number of studies. For PDA, however, the head-outflow relation (HOR) should be given, which is known to contain a high degree of uncertainty. Here, the DDA-based simulator, EPANET2 was modified to develop a PDA model simulating pressure deficient conditions and a Monte Carlo simulation (MCS) was performed to consider the quantitative uncertainty in HOR. The developed PDA model was applied to two networks (a well-known benchmark system and a real-life WDN) and the results showed that the proposed model is superior to other reported models when dealing with negative pressure under abnormal conditions. In addition, the MCS-based sensitivity analysis presents the ranges of pressure and available discharge, quantifying service reliability of water networks.

Use of synthesized hydrophilic magnetic nanoparticles (HMNPs) in forward osmosis for water reuse

Abstract: Forward osmosis (FO) is attracting worldwide attention as an emerging technology in the fields of power generation, water reuse, desalination, pharmaceuticals and food processing. Still, the critical challenge of finding a suitable draw solute for FO persists. Therefore the current research focuses on synthesizing hydrophilic magnetic nanoparticles (HMNPs) and systematically investigating their potential as draw solutes. HMNPs were synthesized using functional groups polyethylene glycol (PEG 400) and polyacrylic acid (PAA). These functional groups under different ratios with a metal precursor react by one-pot polyol and thermal decomposition methods respectively to give different diameter HMNPs. In addition the effect of different sizes of synthesized HMNPs was investigated for their recovery under an external magnetic field and reusability in FO performance. The physical properties and chemical compositions of the resultant MNPs are fully characterized. Transmission electron microscopy (TEM) analyses show the characteristics as spherical morphology with a narrow size distribution, and a mean size from 9 to 32.5 nm for PEG and 8 to 30 nm for PAA coated HMNPs depending on the ratio of the functional group and metal precursor. The PEG and PAA layer on the MNPs is confirmed by Fourier transform infrared (FTIR) analysis, and thermogravimetric analysis demonstrates a hydrophilic surface composition. The PEG and PAA coated HMNPs generate high osmotic pressures and exhibit good dispersibility in aqueous solutions. Water fluxes of >13 L m−2 h−1 are achieved across Hydration Technologies Inc. flat sheet membranes at a concentration of 0.05 M of HMNPs using deionized water as the feed solution. The HMNPs can be easily recaptured from draw solutions by applying an external magnetic field and recycling them back as draw solute in the FO process. The MNPs remain active after nine runs of recycling but with a total water flux decrease of 5% in PEG and 3% with each successive recycling due to slight aggregation, and reduced surface to volume ratio is observed. Results of the present study have demonstrated that PEG and PAA coated HMNPs can viewed as promising and potential draw solutes in the FO process.

Reaching economic leakage level through pressure management

Abstract: High non-revenue water (NRW) values as percentage of system input volume form a serious problem that many water utilities word wide have to confront nowadays. There are ways to mitigate the effect by adopting strategies with short and long term results. Water pressure management (PM) is one of the most efficient and effective NRW reduction strategies. To calculate pressure's management economic level of leakage (ELL) several steps have to be made like full water costing, calculation of economic benefits and losses of PM interventions and defining the related investment's break-even point. In this paper the results of these three procedures required to define the ELL level are analyzed, in order to present the link between them. The water distribution system of Kozani city (in Northern Greece) is used as the case study network. The results of both the net present values PM implementation results and the investment's break-even estimation are analyzed.

Estimating the ratio of pond size to irrigated soybean land in Mississippi: a case study

Abstract: Although more on-farm storage ponds have been constructed in recent years to mitigate groundwater resources depletion in Mississippi, little effort has been devoted to estimating the ratio of on-farm water storage pond size to irrigated crop land based on pond metric and its hydrogeological conditions. In this study, two simulation scenarios were chosen to determine such a ratio as well as to investigate pond hydrological processes using a Structural Thinking, Experiential Learning Laboratory with Animation (STELLA) model, one scenario with and the other without using pond water for irrigation for a typical pond that represented the average conditions in East Mississippi. Simulation results showed that pond water level changed moderately for conditions without using its water for irrigation, whereas such level changed dramatically for conditions with using its water for irrigation. A reasonable ratio of pond size to irrigated soybeans land was 1:18 if the irrigation rate was 2.54 cm d −1 (or 1 in d −1 ) and the low limit of the pond water level was drawn to near zero (0.08 m). For the ratio of 1:18, our simulations further revealed that a 1-ha soybeans land could save about 542 m 3 groundwater each year. This study suggests that the STELLA model is a useful tool for estimating the ratio of pond size to irrigated crop land.

Evaluation of water resources comprehensive utilization efficiency in the Yellow River Basin

Abstract: This study investigated appropriate indicators using the trapezoidal fuzzy number method, and constructed an evaluation index system for water resources comprehensive utilization efficiency (WRCUE). A WRCUE evaluation model is applied to the areas in the Yellow River Basin in China using a genetic projection pursuit method. Results show that WRCUE is well developed in Shanxi, Shandong, and Henan provinces, moderately developed in Shanxi, Inner Mongolia, and Sichuan provinces, and poorly developed in the Ningxia Autonomous Region, Gansu Province, and Qinghai Province. According to the capacities of provinces, related measures are proposed.

Using HPSEC to identify NOM fraction removal and the correlation with disinfection by-product precursors

Abstract: In this study high performance size exclusion chromatography (HPSEC) was used to compare an ultrafiltration (UF) membrane and alum coagulation for their capacity to remove different fractions of natural organic matter (NOM) from water. At the same time, the removal of disinfection by-product (DBP) precursors, as measured by trihalomethane formation potential (THMFP) and haloacetic acid formation potential (HAAFP), was also detected. The results show that the UF membrane mainly removed the aliphatic biopolymer fraction, while alum coagulation mainly removed the humic substances fraction. The results of DBP precursor analysis show that more THMFP was removed by the UF membrane than HAAFP, while the reverse was true for alum coagulation. It is conjectured that the aliphatic biopolymer fraction is the major precursor for trihalomethanes (THMs), while the humic substances fraction is the major precursor for haloacetic acids (HAAs).

Evaluation of novel hollow fibre membranes for NOM removal by advanced membrane autopsy

Abstract: A full-scale inside out hollow fibre membrane module was operated in a pilot-scale water treatment plant in Sweden for a period of 12 months from August 2013 to July 2014. Liquid chromatography– organic carbon detection (LC-OCD) chromatogram indicated the membranes could effectively remove 86% of dissolved organic carbon and 92% of humic substances from the feedwater. Routine cleaning-in-place was conducted to remove any fouling material accumulated on the membranes. Autopsy of the aged membrane samples after 12 months’ operation suggested no significant changes were detected for the membrane samples obtained from the top, middle and bottom sections of the membrane module and were similar to the virgin membrane sample.

Effect of common inorganic ions on aniline degradation in groundwater by activated persulfate with ferrous iron

Abstract: Aniline is widespread in groundwater and of great toxicity. Advanced oxidation processes, such as the ferrous iron (Fe2+)-activated persulfate process, have been proven to be effective for organic pollutants. However, few studies have focused on the effects of coexisting ions on the degradation of aniline. In this study, the degradation efficiency of aniline and the effects of common inorganic ions (CO32−, PO43−, HCO3−, SO42−, NO3−, Na+, K+, Mg2+, and Ca2+) on aniline degradation were examined. Under the optimum operating conditions, 86.33% aniline degradation (C = 11 mmol/L) was observed within 60 min. The effects of cations on aniline degradation were negligible. Anions decreased the removal efficiency of aniline because of the radicals generated by the reaction between sulfate radical or hydroxyl radical and these anions. As the concentrations of PO43−, CO32−, SO42−, HCO3−, and NO3− increased from 0 mmol/L to 5 mmol/L, the removal efficiency of aniline decreased to 19.72%, 24.56%, 66.76%, 68.76%, and 82.42%, respectively. The order of inhibitory effects was PO43− > CO32− > >SO42− > HCO3− > >NO3−.