The dynamic and complex municipal wastewater treatment plant (MWWTP) process should be handled efficiently to safeguard the excellent quality of effluents characteristics. Most of the available mathematical models do not efficiently capture the MWWTP process, in such cases, the data-driven models are reliable and indispensable for effective modeling of effluents characteristics. In the present research, two nonlinear system identification (NSI) models namely; Hammerstein-Wiener model (HW) and nonlinear autoregressive with exogenous (NARX) neural network model, and a classical autoregressive (AR) model were proposed to predict the characteristics of the effluent of total suspended solids (TSSeff) and pHeff from Nicosia MWWTP in Cyprus. In order to attain the optimal models, two different combinations of input variables were cast through auto-correla-tion function and partial auto-correlation analysis. The prediction accuracy was evaluated using three statistical indicators the determination coefficient (DC), root mean square error (RMSE) and correlation coefficient (CC). The results of the appraisal indicated that the HW model outperformed NARX and AR models in predicting the pHeff, while the NARX model performed better than the HW and AR models for TSSeff prediction. It was evident that the accuracy of the HW increased averagely up to 18% with regards to the NARX model for pHeff . Likewise, the TSSeff performance increased averagely up to 25% with regards to the HW model. Also, in the validation phase, the HW model yielded DC, RMSE, and CC of 0.7355, 0.1071, and 0.8578 for pHeff, while the NARX model yielded 0.9804, 0.0049 and 0.9902 for TSSeff, respectively. For comparison with the traditional AR, the results showed that both HW and NARX models outperformed in (TSSeff) and pHeff prediction at the study location. Hence, the outcomes determined that the NSI model (i.e., HW and NARX) are reliable and resilient modeling tools that could be adopted for pHeff and TSSeff prediction.
Diyala River is the third largest tributary of the Tigris River running 445 km length and draining an area of 32,600 km2. The river is the major source of water supply for Diyala City for municipal, domestic, agriculture and other purposes. Diyala River Basin currently is suffering from water scarcity and contamination problems. Up-to-date studies have shown that blue and green waters of a basin have been demonstrating increasing variability contributing to more severe droughts and floods seemingly due to climate change. To obtain better understanding of the impacts of climate change on water resources in Diyala River Basin in near 2046~2064 and distant future 2080~2100, SWAT (soil and water assessment tool) was used. The model is first examined for its capability of capturing the basin characteristics, and then, projections from six GCMs (general circulation models) are incorporated to assess the impacts of climate change on water resources under three emission scenarios: A2, A1B and B1. The results showed deteriorating water resources regime into the future.
Kurdistan in northern Iraq, a semi-arid region, predominantly a pastureland, is nourished by Lesser Zab, which is the second major tributary of Tigris River. The discharge in the tributary, in recent times, has been experiencing increasing variability contributing to more severe droughts and floods supposedly due to climate change. For a proper appreciation, SWAT model has been used to assess the impact of climate change on its hydrological components for a half-centennial lead time to 2046-2064 and a centennial lead time to 2080-2100. The suitability of the model was first evaluated, and then, outputs from six GCMs were incorporated to evaluate the impacts of climate change on water resources under three emission scenarios: A1B, A2 and B1. The results showed worsening water resources regime.
SWAT model (Sediment and Water Assessment Tool) was used to evaluate the impacts of climate change on water resources in Al-Adhaim Basin which is located in north east of Iraq. Al-Adhaim River is the main source of fresh water to Kirkuk City, one of the largest cities of Iraq. Recent studies have shown that blue and green waters of the basin have been manifesting increasing variability contributing to more severe droughts and floods apparently due to climate change. In order to gain greater appreciation of the impacts of climate change on water resources in the study area in near and distant future, SWAT (Soil and Water Assessment Tool) has been used. The model is first tested for its suitability in capturing the basin characteristics, and then, forecasts from six GCMs with about half-a-century lead time to 2046-2064 and one-century lead time to 2080-2100 are incorporated to evaluate the impacts of climate change on water resources under three emission scenarios: A2, A1B and B1. The results showed worsening water resources regime into the future.
The Khabour River is one of five tributaries of Tigris River and the first river flows into Tigris River contributing to Tigris Flow by about 2 BCM at Zakho Station. The area of this catchment is 6,143 km2, of which 57% are located in Turkey and 43% in Iraq with a total length of 181 km. Khabour River is the main source of fresh water to Duhok City, one of the major cities of Kurdistan Region. Hydrometeorological data over the past several decades reveal that the catchment is experiencing increasing variability in precipitation and stream flow contributing to more severe droughts and floods presumably due to climate change. SWAT model was applied to capture the dynamics of the basin. The model was calibrated at Zakho station. The performance of the model was rather satisfactory; R2 and ENC were 0.5 and 0.51, respectively in calibration period. In validation process R2 and ENC were nearly consistent. In the next stage, six GCMs from CMIP3 namely, CGCM3.1/T47, CNRM-CM3, GFDL-CM2.1, IPSLCM4, MIROC3.2 (medres) and MRI CGCM2.3.2 were selected for climate change projections in the basin under a very high emissions scenario (A2), a medium emissions scenario (A1B) and a low emissions scenario (B1) for two future periods (2046-2064) and (2080-2100). All GCMs showed consistent increases in temperature and decreases in precipitation, and as expected, highest rate for A2 and lowest rate for B1. The projected temperatures and precipitation were input to the SWAT model to project water resources, and the model outputs were compared with the baseline period (1980-2010), the picture that emerged depicted deteriorating water resources variability.
The limited amount of freshwater is the most important challenge facing Egypt due to increasing population and climate change. The objective of this study was to investigate how climatic change affects the winter potato water footprint at the Nile Delta covering 10 governorates from 1990 to 2016. Winter potato evapotranspiration (ETC) was calculated based on daily climate variables of minimum temperature, maximum temperature, wind speed and relative humidity during the growing season (October–February). The Mann–Kendall test was applied to determine the trend of climatic variables, crop evapotranspiration and water footprint. The results showed that the highest precipitation values were registered in the northwest governorates (Alexandria followed by Kafr El-Sheikh). The potato water footprint decreased from 170 m3 ton−1 in 1990 to 120 m3 ton−1 in 2016. The blue-water footprint contributed more than 75% of the total; the remainder came from the green-water footprint. The findings from this research can help government and policy makers better understand the impact of climate change on potato crop yield and to enhance sustainable water management in Egypt’s major crop-producing regions to alleviate water scarcity.
Practicing agricultural drainage strategies is necessary to manage excess water in poorly drained irrigated agricultural lands to protect them from induced waterlogging and salinity problems. This paper provides an overview of subsurface drainage strategies and the modeling of their performance using the DRAINMOD model. Given that the DRAINMOD model considers a fixed value of the surface depression capacity (SDC) for the whole simulation period, which does not suit many agricultural practices, the paper then assesses the model’s performance under time-variable SDC. It was revealed that adopting a fixed value of SDC for the whole simulation period in the DRAINMOD model causes it to produce improper predictions of the water balance in farmlands characterized by time-variable SDC. Such a model drawback will also adversely impact its predictions of the nitrogen and phosphorus fate in farmlands, which represent major inputs when managing both the agricultural process and agricultural water quality. Researchers should pay attention when applying the DRAINMOD model to farmlands characterized by time-variable SDC. Moreover, it is recommended that the DRAINMOD input module be improved by considering changes in SDC during the simulation period to ensure better management of the agricultural process and agricultural water.
During recent years a hybrid model has been set up for the operational forecasting of flood discharges in the 6750km 2 Tyrolean part of the River Inn catchment in Austria. The catchment can be characterized as a typical alpine area with large variations in altitude. The paper is focused on the error analysis of discharge forecasts of four main tributary catchments simulated with hydrological water balance models. The selected catchments cover an area of 2230km 2, where the non-glaciated and glaciated parts are modeled using the semi-distributed HQsim and the distributed model SES, respectively.The forecast errors are evaluated as a function of forecast lead time and forecasted discharge magnitude using 14 events from 2007 to 2010. The observed and forecasted precipitation inputs were obtained under operational conditions. The mean relative bias of the forecasted discharges revealed to be constant with regard to the forecast lead time, varying between 0.2 and 0.25 for the different catchments. The errors as a function of the forecasted discharge magnitude showed large errors at lower values of the forecast hydrographs, where errors decreased significantly at larger discharges being relevant in flood forecasting
Iraq depends on its water resources from the water of the Tigris and Euphrates Rivers and their tributaries. Now, the flow of these rivers is decreasing, and Iraq is experiencing a water shortage problem. The situation is expected to be graver in the future if no action is considered. It is expected that the population will be about 70 million in 2050 and about 90 million in 2070. In such a case, thus, the quantities of water available in the future will not besufficient to produce most of the requirements of food security, whether that be from agricultural or animal products. To overcome this problem, water management planning should be based on scientific background to overcome the present and expected problems. One of the main factors to be considered should be based on scientific studies of the virtual water footprint of different food crops to provide the largest possible amount of virtual water and avoid the acute shortage of its national water from surface and ground irrigation water (blue water) and rainwater (green water), in addition to working hard to provide the largest possible amount of desalinated water and refined sewage (gray water). In addition, any strategic plan for sustainable development in the country must be comprehensive so that it is not satisfied with improving the situation in the field of food security related to water security, but rather among its other elements is community development that directly affects food security, including setting policies to reduce consumption by reducing the steady increase in population where the population rate is 2.97% now. Collective awareness and guidance programs in all the fields of water and food security are very important to be adopted, so that everyone knows that the issue of food security and what derives from it are an existential issue related to the survival of Iraq as a state and people. In this research, facts are stated so that action is to be considered to minimize the water shortage problem. The new strategic water resources management plan is to be adopted that considers existing and future expected problems.
The Hydraulic Institute has completed the task of developing a new ANSI/HI standard 12.1-12.6 (2005) for rotodynamic (centrifugal) slurry pumps covering nomenclature, definitions, applications, and operation. The standard provides examples of the different slurry pump types and contains an extensive section on pump and slurry definitions. The effect of slurry on pump performance is covered along with the pumping of froth. Reference is also made to ANSI/HI standard 9.6.7 (2004), which contains a new method for pump performance correction when handling viscous fluids. Classification of slurry services is established and then is used to determine limitations on velocities and total head per pump in order to obtain acceptable wear performance. The new service class, head per stage and other limits are directly related to capital and other cost considerations that will affect solids transport system economics. The writers review the contents of the new standard, highlight the main points, and discuss the reason for the slurry classification, corresponding limits and expected implications, particularly with respect to operating costs of the pumps in solids transport systems
There is a wide variety of industrial pastes or non-settling slurries pumped in mining, dredging and reclamation projects as products, refuse and tails. The types and/or names of some of the common ones are alumina red mud, phosphate clays, tar sands mature fine tails, tar sands (CT) consolidated clays and fly ash. The pipeline performance or friction of these varies dramatically with the type, its concentration and the particulars of the actual slurry making it difficult to select pumping equipment and to design associated pipelines. The GIW Hydraulic Laboratory in Grovetown Georgia has tested a number of these slurries over the last 30 years for various mining customers. Where available in the public domain and/or where permission has been obtained, the results of those tests are presented in this paper in a form usable for pipeline and pump system designers and users.
The Hydraulic Institute has completed the task of developing a new ANSI/HI standard 12.1-12.6 (2005) for Rotodynamic (Centrifugal) Slurry Pumps covering nomenclature, definitions, applications, and operation. The standard provides examples of the different slurry pump types and contains an extensive section on pump and slurry definitions. The effect of slurry on pump performance is covered along with the pumping of froth. Reference is also made to ANSI/HI standard 9.6.7 (2004), which contains a new method for pump performance correction when handling viscous fluids.Classification of slurry services is established and then is used to determine limitations on velocities and total head per pump in order to obtain acceptable wear performance. The new service class, head per stage and other limits are directly related to capital and other cost considerations that will affect solids transport system economics. The writers review the contents of the new standard, highlight the main points, and discuss the reason for the slurry classification, corresponding limits and expected implications, particularly with respect to operating costs of the pumps in solids transport systems.
The Hydraulic Institute has just completed the task of developing a new ANSI/HI standard on Rotodynamic (Centrifugal) Slurry Pumps covering nomenclature, definitions, applications, and operation. The standard provides examples of all the different types of pumps available and has an extensive section on definitions. Slurries and their effect on performance and wear are covered. A slurry service class is established which then is used to limit velocities and head produced per pump to give acceptable wear. A special section deals with mechanical seals and a new method for determining flange loads is presented and guidelines are given for commissioning, start-up etc.The head limits and the performance derating are of special interest when centrifugal slurry pumps are applied to thickened tailings and paste-like slurries. For Newtonian liquids, the Hydraulic Institute's Viscosity Correction Method (ANSI/HI 2004) provides a procedure widely used for viscous effects on the performance. For the homogeneous flow of viscous slurries, the new slurry standard refers to an applicable viscosity to use with the method and to "consult the pump manufacturer for guidance regarding non-Newtonian slurry pump performance."Experimental performance results are presented here and applied to the viscosity correction method for a simulated tailings product slurry characterized by a fully sheared yield stress of about 100 Pa, evaluated from pipeline data. The pump was a GIW-LCC type three-vane all metal unit with a 0.3m-diameter impeller having an open shroud with a simple auger-like inducer. Results are also given for an underground hydraulic fill product characterized by a Newtonian kinematic viscosity which is 1300 times that for water. The different results obtained here point out the strong influence the rheological behavior has on the choice of pump size and the power requirement.
Cyclone feed centrifugal slurry pumps in semi-autogenous grinding (SAG) mill and other cyclone feed circuits see coarse size slurries at high concentrations that can result in high wear if the pump is not designed, selected, sized and operated correctly. The high proportion of static head of the normal cyclone feed circuits usually results in a relatively flat system curve which in conjunction with the typically flat slurry pump curve results in large changes in operating flow with small changes in system head. When this is combined with the normal (or abnormal) fluctuations in the output from the mill upstream of the pumps, any shortcomings in the pump control system and/or matching of the pump means large fluctuations in flow and increased wear. This difficulty could be corrected by continuous variations in speed. A means of control by which the speed is changed in an appropriate way is suggested here. In this case then the pump-input power, the known water performance of the pump and the system flow, can be used to calculate an effective pump discharge pressure. By comparison with a calculated system head, the pump speed can be regulated such that the pressures are equal and the system stable for any practical variation of incoming flow or specific gravity.
Pollution of a watershed by different land uses and agricultural practices is becoming a major challenging factor that results in deterioration of water quality affecting human health and ecosystems. Sustainable use of available water resources warrants reduction of Non-Point Source (NPS) pollutants from receiving water bodies through best management practices (BMPs). A hydrologic model such as the Soil and Water Assessment Tool (SWAT) can be used for analyzing the impacts of various BMPs and implementing of different management plans for water quality improvement, which will help decision makers to determine the best combination of BMPs to maximize benefits. The objective of this study is to assess the potential reductions of sediments and nutrient loads by utilizing different BMPs on the Yarra River watershed using the SWAT model. The watershed is subdivided into 51 sub-watersheds where seven different BMPs were implemented. A SWAT model was developed and calibrated against a baseline period of 1998–2008. For calibration and validation of the model simulations for both the monthly and annual nutrients and sediments were assessed by using the Nash–Sutcliffe efficiency (NSE) statistical index. The values of the NSE were found more than 0.50 which indicates satisfactory model predictions. By utilizing different BMPs, the highest pollution reduction with minimal costs can be done by 32% targeted mixed-crop area. Furthermore, the combined effect of five BMPs imparts most sediments and nutrient reductions in the watershed. Overall, the selection of a BMP or combinations of BMPs should be set based on the goals set in a BMP application project.
It is important to determine the limits of flow regimes in the design of stepped weirs because of the hydraulic performance of each regime. The present study investigates the effect of downstream slope and rock fill materials on flow regimes in gabion stepped weirs. Nine physical models of gabion weirs were used in the experiments. The models’ downstream slopes ranged from 1:05 to 1:4 V:H. In addition, two types of rockfill materials: crushed stone of 0.42 porosity and rounded gravel of 0.38 porosity were used to study the effect of rockfill materials on flow regimes. The nominal size of the crushed stone was (37.5 mm - 13.2 mm) D50 = 23 mm and the nominal size of the rounded gravel was (26.5 mm - 13.2 mm) D50 = 16 mm. Each model has been tested with ten runs for discharge per unit width ranging (from 0.006 to 0.105 m3/sec. m) to cover all flow conditions and flow regimes. The onset of each flow regime for all physical models has been observed. The experimental data of the gabion stepped weirs have been used to develop equations to estimate the onset of each flow regime. The coefficient of correlation (R) of the developed equations ranged between 0.95 to 0.97. The results indicated on the steeper downstream slope models (1:0.5, 1:0.83), there is interference between the nappe and transition flow regimes. The nappe flow regime has not appeared on all steps at the same time. Moreover, the shape and size of the rockfill materials have an insignificant effect on flow regimes, especially at a high flow rate.
Rivers Euphrates and Tigris are in southwest Asia. The main utilizers of the water of these rivers and tributaries are Turkey, Syria, Iran and Iraq. These rivers rise in Turkey, which makes it the riparian hegemon. Some of the tributaries of the Tigris and Shat Al-Arab Rivers rise in Iran, which makes it the riparian hegemon for these rivers. The lower countries in the catchments are Iraq and Syria and for this reason, they always to ensure the quantity of water required to satisfy their requirements. All these countries are in the Middle East (ME), which characterized by its shortage of water resources. Since the 1970s conflict between riparian counties were noticed due to shortage of available water required, high population growth rate and food security, energy requirements, economic and technological developments and political fragmentation. In addition, there is no public awareness program in all riparian countries and the water management practices are so old leading to high rate of losses. This caused tensions, which sometimes escalated to the verge of war. A mediator is required that is capable to bring all countries concerned to the negotiation table. Syria and Iraq are to give Turkey and Iran some incentives to cooperate. Furthermore, strategic plan based on comprehensive resources development to ensure good water management, minimum water loses, and waste must be adopted by the countries within the basins. This due to the fact that modeling studies of the future suggest that water shortage problem will intensify.
Modelling drought is vital to water resources management, particularly in arid areas, to reduce its effects. Drought severity and frequency are significantly influenced by climate change. In this study, a novel hybrid methodology was built, data preprocessing and artificial neural network (ANN) combined with the constriction coefficient-based particle swarm optimisation and chaotic gravitational search algorithm (CPSOCGSA), to forecast standard precipitation index (SPI) based on climatic factors. Additionally, the marine predators algorithm (MPA) and the slime mould algorithm (SMA) were used to validate the performance of the CPSOCGSA algorithm. Climatic factors data from 1990 to 2020 were employed to create and evaluate the SPI 1, SPI 3, and SPI 6 models for Al-Kut City, Iraq. The results indicated that data preprocessing methods improve data quality and find the best predictors scenario. The performance of CPSOCGSA-ANN is better than MPA-ANN and SMA-ANN algorithms based on various statistical criteria (i.e., R2, MAE, and RMSE). The proposed methodology yield R2 = 0.93, 0.93, and 0.88 for SPI 1, SPI 3, and SPI 6, respectively.
Partikeldynamik i Luleås dricksvattennät
Severe droughts and mismanagement of water resources during the last decades have propelled authorities in the Kurdistan Region to be concerned about better management of precipitation which is considered the primary source of recharging surface and groundwater in the area of interest. The drought cycles in the last decades have stimulated water stakeholders to drill more wells and store uncontrolled runoff in suitable structures during rainy times to fulfill the increased water demands. The optimum sites for rainwater harvesting sites in the Qaradaqh basin, which is considered a water-scarce area, were determined using the analytical hierarchy process (AHP), sum average weighted method (SAWM), and fuzzy-based index (FBI) techniques. The essential thematic layers within the natural and artificial factors were rated, weighted, and integrated via GIS and multi-criteria decision-making (MCDM) approaches. As a consequence of the model results, three farm ponds and four small dams were proposed as future prospective sites for implementing rainwater harvesting structures. The current work shows that the unsuitable ratio over the study area in all methods AHP, SAWM, and FBI occupied 12.6%, 12.7%, and 14.2% respectively. The area under the curve (AUC) and receiver operating characteristics were used to validate the model outcomes. The AUC values range from 0.5 to 1, meaning that all MCDM results are good or are correctly selected. Based on the prediction rate curve for the suitability index map, the prediction accuracy was 72%, 57%, and 59% for AHP, SAWM, and fuzzy overlay, respectively. The final map shows that the potential sites for rainwater harvesting or suitable sites are clustered mainly in the northern and around the basin’s boundary, while unsuitable areas cover northeastern and some scatter zones in the middle due to restrictions of geology, distance to stream with the villages, and slope criteria. The total harvested runoff was 377,260 m3 from all the suggested structures. The proposed sites may provide a scientific and reasonable basis for utilizing this natural resource and minimize the impacts of future drought cycles.
Underground thermal energy storage (UTES) systems are widely used around the world, due to their relations to heating ventilating and air conditioning (HVAC) applications [1]. To achieve the required objectives of these systems, the best design of these systems should be accessed first. The process of determining the best design for any UTES system has two stages, the type selection stage and the site selection stage. In the type selection stage, the best sort of UTES system is determined. There are six kinds of UTES systems, they are: boreholes, aquifer, bit, tank, tubes in clay, and cavern [2–5]. The selection of a particular type depends on three groups of parameters. They are: Site specific, design, and operation parameters (Figure 1). Apart from site specific parameters, the other two types can be changed through the life time of the system. The site specific parameters, e.g., geological, hydrogeological, and metrological, cannot be changed during the service period of the ystem. Therefore, the design of the best type should depend, at first consideration, on site specific parameters.
Underground Thermal Energy Storage UTES systems are widely used around the world. The reason is that UTES is essential in utilizing Renewable Energy sources (RE). The efficiency of the energy system relies strongly on the efficiency of the storage system. Therefore, in the installation of a hyper-energy system, a lot of attention is to be paid in improving the storage system. In order to design an efficient storage system, firstly, standard criteria are to be investigated. These explain the process of making high efficiency storage system that must be specified. The criteria, mainly, depends on: best type and best location. These two variables are in high interference with each other. The bond between the two variables is represented by the geological, hydrological, meteorological, soil, hydrogeological properties/factors of the site. These factors are specified by geo-energy mapping. Despite the importance of this type of mapping, there is no specific criteria/formula that defines the choice. This paper aims to: give a brief literature review for UTES systems (types, classification, advantages/disadvantages for each type, and examples of an installed system). In addition, some factors within geo-energy mapping are highlighted and standard criteria to achieve good storage system are suggested. The suggested criterion comprises a process to transfer the quantity values to quality values according to the expert opinion. The suggested criteria are defined through the following stages: selecting the best type of UTES systems according to hydro-geological in site conditions; using the analytical hierarchy process to rank the best location to install the storage system and then using ArcMap (GIS-Software) to provide representative results as maps. Karbala Province (Iraq) is the study area used here
There is a global attention that the future energy systems will be based on renewable energy like solar and wind. The large-scale utilization of renewables in space heating and cooling requires large Thermal Energy Storage TES to overcome the varying supply and demand. The process of producing the best Underground Thermal Energy Storage UTES system pass through two steps: first, finding the best type of UTES system, second, finding the best locations to install UTES system. Both of these two steps depend extremely on the site specific parameters such that the depth to the groundwater, transmissivity, type of soil, the depth to the bedrock, and seepage velocity. The purpose of this paper is to explain some of the site specific parameters that the type of UTES-system depends on and explain the suitable type of UTES systems. This study considers Babylon province (Iraq) as study area. This province has electricity deficiency due to Heating Ventilating and Air Conditioning HVAC applications. The methodology of this study includes reviewing the literature that consider the study area, and using Arc Map/GIS to visualize some of the in-site parameters. The results indicate that the best type of UTES system for the considered region is either aquifer or pit type, due to the type of the soil and the depth to the crystalline bedrock. The hydraulic conductivity and the seepage velocity in the considered region are (0.0023–2.5) m/d and (1.3 × 10−6 – 3.45 × 10−3) m/d respectively. These conditions satisfy the standards which regard aquifer type.
Maintaining natural processes and supporting social and economic growth depend heavily on water supplies. However, Future climate is predicted to bring higher temperatures, which will increase evapotranspiration; lower precipitation totals; and changes in the seasonal pattern of precipitation. Iraq is more vulnerable to climate change than other nations due to the underdeveloped and fragile water management systems there, as well as the country's desert and warmer environment and increasing sensitivity to extreme weather events. The present work aims to analyse the literature dealing with climate change's effects on water resources in Iraq. The Scopus database was searched using the keywords (Iraq, models of climate change, and water resources). Most models study the effect of high temperatures and evaporation on water resources using different tools, the most important of which are SWAT, LARS-WG, and HEC-HM. The analysis of previous studies shows that the results of all the literature concordant that Iraq is on the verge of severe water scarcity due to high temperatures and the resulting decrease in rainfall, increase in evaporation, decrease in vegetation cover and increase in desertification.
Water used for irrigation is accounted for 70%–80% of the total water used worldwide. Thus, efficient management of the water resources is the key point to the sustainable water use. The difference between the inflow and water needs is one of the reasons for constructing a reservoir. Many studies were conducted regarding optimizing reservoir operation for irrigation to achieve the desired goals and objectives of the reservoir system. Significant and increasing scientific efforts were conducted to develop and implement the optimization techniques to operate the reservoirs for irrigation. All of the literature aims to minimize the gap between the water release policy and water demands determine release and transfer decisions that maximize water management objectives, and they all confirmed that using mathematical models to optimize and simulate the reservoir operation can enhance the performance of the reservoirs, as well as improve the crop yield. It is expected that this direction continues to evolve, and hopefully, the results of these models would encourage water managers to put them into practice to upgrade the agricultural sector.
The concentrations of several selected organic hazardous substances were investigated in domestic graywater. In total, 41 of 81 organic hazardous substances were found in concentrations above the detection limits (nonylphenol and octylphenol ethoxylates, brominated flame-retardants, organotin compounds, polyaromatic hydrocarbons, polychlorinated biphenyls, phthalates, linear-alkyl benzene sulfonate, and triclosan). Moreover, total solids, biochemical oxygen demand (BOD7), chemical oxygen demand (COD), total nitrogen, total phosphorus, potassium, and sulphur were investigated and presented for graywater. Another objective was to suggest potential household sources for a selected number of organic hazardous substances. The present and past investigations reveal households to be obvious contributors of organic hazardous substances to municipal wastewater, and that graywater is an important media in this transport. The spreading derives from diffuse household sources like everyday activities (laundry, cleaning, etc.), the wearing down of things such as pipe material and interior fittings, and from airborne deposition.
Constructed stormwater wetlands (CSWs) are a commonly used measure for stormwater retention and quality treatment. However, although questions have been raised about the long-term performance of CSWs, only a few studies have targeted this issue and none have evaluated the performance of CSWs more than approximately 5–10 years old. Further, most studies have not examined the development of the long-term performance of CSWs but delivered a snapshot at a certain point of time. The present study investigated the performance of a 19-year-old CSW in Växjö, Sweden, treating stormwater from a 320-ha urban catchment. Besides removal of sediment from the CSW’s forebay, no other maintenance had been conducted. However, regular inspections had been performed. The results of the present sampling campaign were compared to two existing datasets collected at the same CSW after three years of operation in 1997 and nine years of operation in 2003. The CSW was found to provide efficient peak flow reduction and, depending on the event characteristics, also volume reduction. It still treated stormwater effectively: removal of Cd, Cu, Pb, Zn, TSS and TP event mean concentrations were between 89 and 96%, whereas mean concentrations of TN were reduced by 59%. The load removal efficiencies were even higher. Comparative analysis of the three monitoring periods based on the load removal efficiency revealed that the CSW, despite the lack of maintenance, performed more efficiently and stably for most pollutants compared to when newly constructed. This underlines the importance of the establishment and maturation of constructed wetland systems. Overall, the results showed that CSWs are resilient systems, which if designed well and regularly inspected to prevent major issues, can work efficiently for at least two decades.
This paper examined the factors influencing the long-term hydraulic performance of some stormwater infiltration systems (swale and two types of permeable pavements) in Växjö, southern Sweden. The infiltration capacities of 9 permeable pavements and 2 swales sites, all with different ages ranging from 1 year to 14 years, were measured using replicate double ring infiltrometers. The sites were either constructed of swale (2), interlocking concrete pavers (ICP) filled with gravel (2), concrete grid pavers (CGP) filled with gravel (3), or concrete grid pavers (CGP) filled with grass (4). The results of this study showed that the long-term behaviour of the infiltration capacity relies largely on the type and age of the system and the type of joint filling (gravel and grass). Furthermore, the study showed that the 11 year old concrete grid pavers filled with grass had the highest infiltration capacity (4.80 + 2.46 mm/min), whilst the 9 and 14 year old swales had the lowest infiltration capacity (0.10 + 0.00 mm/min).
During the past 50 years, wet stormwater ponds have been constructed to reduce negative environmental impacts of urban stormwater discharges on receiving aquatic environments. However, in many jurisdictions there is little information on the current operational status of such ponds and their functioning. This paucity of information prompted a field survey of 25 Swedish municipal stormwater ponds, aged between 3 and 26 years. The pond survey focused on estimating the pond hydraulic loading and efficiency, the state of littoral vegetation, characteristics of bottom sediment in the inlet and outlet zones (sizes and the chemistry), and the overall operational pond status, including the access for maintenance. The hydraulic efficiencies of ponds were estimated for pond footprint shapes and relative locations of the inlets and outlets using literature data. The estimated hydraulic efficiencies correlated well with the pond length-to-width ratios and the ratio of the pond surface area to the impervious area of the runoff contributing catchment (i.e., the hydraulic loading). Littoral vegetation was inspected visually and found to be overgrown at some facilities, which impeded the maintenance access. Benthic sediments in ponds contained silt and clay (<63  μm" role="presentation" style="box-sizing: border-box; display: inline; line-height: normal; word-spacing: normal; word-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px; margin: 0px; position: relative;"><63 μm<63 μm), sand and gravel fractions, and when compared with the literature data, such sediments appeared relatively coarse. Chemical characteristics of sediments reflected anthropogenic (traffic) activities, but without excessive contamination warranting special disposal requirements. Of the 25 ponds surveyed, four were fenced off and inaccessible to machinery. In fact, the design of these four ponds was such that it made inspection and maintenance very difficult, which may pose potential risks to ponds operation. Fifty-four percent of the investigated ponds were in need of minor maintenance, primarily because of sediment and litter accumulation in their inflow and outflow sections. The fact that the inspection survey revealed relatively few minor issues that could be corrected easily demonstrates the importance of relatively simple regular inspections serving to detect minor problems at an early stage before they would seriously impact pond functioning. The above survey methodology should be helpful for developing similar low-cost surveys in other jurisdictions.
This study monitored the stormwater runoff quantity and quality treatment performance of a 6.8 ha 19-year old combined pond-wetland system, located in south Sweden, over one year. The mean volume reductions for 53 storm events for the pond and wetland were 40% and 28%, respectively, while the mean flow reductions were 60% and 76%, respectively. Pollutant concentrations in the influent to the wetland were highly variable. The pond-wetland system could efficiently remove an average of 91%, 80%, 94%, 91%, 83% and 92% of TSS, TP, particulate Cd, Cu, Pb, and Zn, respectively, whereas the removal of particulate and dissolved Ni was highly variable with an average of 67% ± 62% and −5% ± 41%, respectively. The removal of TN, NH4-N and NO3 + NO2-N was highly variable with an average of 45% ± 27%, 12% ± 96% and 45% ± 43%, respectively. These removal percentages are high in comparison to other studies and underline that relatively old systems can also provide efficient treatment. Although the pond accounted for a substantial reduction of pollutant concentration, the wetland significantly enhanced both the treatment performance and the peak flow reduction. This underlines that a combined pond/wetland system is a more beneficial solution than a pond only. The pollutant removal efficiency was significantly influenced by some factors including Antecedent Dry Days, seasonal variations, air temperature, retention times, rainfall depth and duration, and peak rainfall intensity.
Constructed stormwater wetlands (CSWs) are commonly used in Sweden and worldwide because of their high efficiency in urban stormwater management. However, questions have been raised about the long-term performance of CSWs. This study investigated the performance of a 19-year-old constructed wetland, which was designed to treat the stormwater from a 320-ha catchment located in the city of Växjö, southern Sweden. The system has not been maintained since its construction in 1994. The results of the present study were compared with results obtained from a previous study conducted by Växjö Municipality in 1997. The results showed that the CSW significantly reduced peak flows by 72%. High concentration reductions were found for Cd, Cr, Cu, Zn, Pb, TSS and TP (90, 89, 91, 90, 96, 96 and 86%, respectively). TN concentrations were reduced by 61%. The results indicated that lack of maintenance had no effect on the performance of wetland system during this long period of operation (19 years). In contrast, especially the removal of Cu and nitrogen was enhanced compared to 1997, which may be due to maturing of the system. The results show that CSWs are resilient systems, which (provided that design is sufficient) can work efficiently for at least two decades.
Objective: The main threat for the performance of porous asphalt is clogging leading to decreased infiltration capacity. Thus, we investigated the potential of vacuum cleaning to recover the infiltration capacity of clogged permeable asphalts which have been in use for several decades. The influence of road operation and maintenance measures on the results was discussed.Method: We investigated the hydraulic conductivity (HC) of two roads with porous asphalt in Haparanda and Luleå, Sweden, which had been in use for 28 years and 15 years, respectively. A lack of appropriate maintenance during their operating life had lead to significant clogging and thus malfunction. The roads were vacuum cleaned using a vacuum cleaner/sweeping truck combination. This technology is recommended as a maintenance option for porous asphalt. Before and after the vacuum cleaning, replicate HC measurements were conducted using double-ring infiltrometers.Result: Before vacuum cleaning, mean HC was <0.1mm/min in Haparanda and between 0.4 and 0.8 mm/min in Luleå. After vacuum cleaning, HC increased significantly in Luleå (between 1.1 and 7.1mm/min) while no significant increase was detected in Haparanda. Despite the improvement after vacuum cleaning, HC was still far lower than the initial HC after construction. Reasons for the different results in Haparanda and Luleå were identified; the road winter maintenance was of primary importance.Conclusion: Depending on the extent of clogging, vacuum cleaning has the ability to recover HC of porous asphalt. However, long term behaviour of the HC depends largely on the street maintenance, thus regular appropriate maintenance is preferable.
The effect of clogging on the long-term infiltration capacity and porosity of two 18- and 24-year-old porous asphalts was examined by using replicate double-ring infiltrometer tests and analyzing asphalt core samples. Tests were carried out to see if high pressure washing and vacuum cleaning could restore the hydraulic performance. The infiltration capacity of the porous asphalts decreased substantially, primarily due to surficial clogging (0.50 +/- 0.26 in Lulea, Sweden, and 0.22 +/- 0.12 in Haparanda, Sweden, compared to initially > 290 mm min(-1)). In Lulea, washing and vacuum cleaning could partially restore the infiltration capacity (3.48 +/- 3.00 mm min(-1)), but in Haparanda, no effect was measured. The porosity was constantly between 16 and 18%. The difference of the long-term behavior and effect of cleaning in Lulea and Haparanda is primarily attributable to different street maintenance, age, and winter maintenance (application of fine gravel and/or sand). Although the infiltration capacity in Lulea was far below initial values, the asphalt still has the capacity to infiltrate an intense design rainfall (100 year average return interval, 15 min duration), underlining that porous asphalt can be a resilient feature also under nonfavorable conditions
Despite the common use of stormwater infiltration systems, there is still only limited data available evaluating the long-term hydraulic function of such systems. The hydraulic performance of twelve stormwater infiltration systems (vegetated and unvegetated concrete grid pavers, unvegetated interlocking concrete pavers and grassed swales) was therefore investigated in field and laboratory environments in Växjö, Sweden. The systems investigated had not been subjected to regular maintenance to sustain infiltration capacity. Due to this, and the fact that, for most systems, an inappropriate joint filling material was used and (at the swales) there was severe compaction, most systems showed a reduced infiltration capacity. Despite this, especially the older vegetated systems, were still capable of infiltrating intense design rainfalls. This study showed the influence of some factors (type and age of the system, the type of joint filling material (grass and macadam) and the distance from the edge of the pavement) on the long-term behaviour of the infiltration capacity. In conclusion, there is a significant risk that existing stormwater infiltration systems are not working adequately in praxis. Proper implementation of construction and regular control by the inspecting authority has to be ensured.
Disease related to unsafe water, poor sanitation, and lack of hygiene is some of the most common causes of illness and death all around the world. Since the first detection of Legionella in Philadelphia 1976, Legionella is recognized to cause Legionellosis which is associated with two distinct forms: Legionnaires’ disease and Pontiac fever. The fact that vaccination against Legionella disease is not efficacious enhances the effort towards developing the existence disinfection methods and inventing new technologies. Re-colonization of Legionella in hot water systems may occur within a few days or weeks after disinfection since conventional disinfection methods significantly reduce but do not eliminate pathogens. Understanding the conditions favoring Legionella occurrence in hot and cold systems will aid in developing new treatment technologies that minimize or eliminate human exposure to legionella pathogens. The work introduces the Anti-Bact Heat Exchanger (ABHE) system as a new innovative system inspired by nature. Compared to conventional disinfection methods, the ABHE system proposed to achieve continuous thermal disinfection of bacteria in hot water systems and in simultaneously saving energy and reducing the required costs. Thermodynamic analysis, experimental test and simulation validation of the ABHE by the Engineering Equation Solver (EES)-based model were achieved to define the thermal performance of the ABHE system at given operation conditions. The experimental test shows high potential of recovering heat and thus saving energy by the ABHE system. In addition, pumping power (PP) was relatively small compared to the recovered heat which implies that less energy was required compared to the recovered heat. The effect of working parameters such as temperatures and flow rate on the thermal performance of the ABHE system was furthermore investigated. The study shows that supplied water temperature has similar effects as the disinfection temperature. Namely, increasing supplied water temperature enhances the regeneration ratio (RR) but it requires a large plate heat exchanger (PHE) area and PP. On the contrary, increasing the temperature in use results in a reduced PHE area and PP. Flow rate has the greatest influence on the thermal performance of the ABHE system. Increasing flow rate leads to an increase in the required area of the PHE. The EES-based model investigated the effect of the length and the width of the plates used in the PHE on the RR and the required area of the PHE. Then, the EES-based model was used to optimize the ABHE system in which the PHE area is minimized or the RR of the ABHE system is maximized.
The work refers to an innovative system inspired by nature that mimics the thermoregulation system that exists in animals. This method, which is called Anti Bacteria Heat Exchanger (ABHE), is proposed to achieve continuous thermal disinfection of bacteria in hot water systems with high energy efficiency. In particular, this study aims to demonstrate the opportunity to gain energy by means of recovering heat over a plate heat exchanger. Firstly, the thermodynamics of the ABHE is clarified to define the ABHE specification. Secondly, a first prototype of an ABHE is built with a specific configuration based on simplicity regarding design and construction. Thirdly, an experimental test is carried out. Finally, a computer model is built to simulate the ABHE system and the experimental data is used to validate the model. The experimental results indicate that the performance of the ABHE system is strongly dependent on the flow rate, while the supplied temperature has less effect. Experimental and simulation data show a large potential for saving energy of this thermal disinfection method by recovering heat. To exemplify, when supplying water at a flow rate of 5 kg/min and at a temperature of 50 °C, the heat recovery is about 1.5 kW while the required pumping power is 1 W. This means that the pressure drop is very small compared to the energy recovered and consequently high saving in total cost is promising.
Since the first recognized outbreak of Legionnaires' disease (LD) in 1976, it has become an increasing problem around the world especially in poor countries. Legionella (L) causes an estimated 15,000 annual cases of pneumonia in USA, and leads to death in about 20% of the cases. L is found worldwide in both natural and artificial environments e.g. spa pools, cooling towers. It infects people by inhaled contaminated aerosols that can transmit several km. The optimal temperature for L growth is 20-45C. Control of L is therefore an important health issue. Many treatment methods are used; biocides, ionisation, ozone, UV-radiation, pressure, and thermal treatment. Only thermal treatment can completely eliminate L, which is killed almost instantly at 70C. Current paper gives an overview of the Legionella problem and treatment methods.
The buildings thermal function is important to provide comfort to its tenants. This means to provide cooling during hot seasons and/or heating in cold season. Current study concerns modelling of a new design of thermal photo sensors that results in a more efficient heating for Tlemcen site, Algeria.
Much work has been carried out on hot water storage during the last 20-30 years, particularly on solar heat applications. Theoretical and experimental studies on the internal heat transfer have been made at laboratory scale and at larger scales. Current study, which was conducted in order to understand the stratification phenomena, involved an experimental study on the thermal behaviour in a hot water tank during charging and discharging for domestic hot water storage. Results showed no effect of stratification due to the injection fluid from the bottom of the tank and the effect of mixed convection induced by the temperature difference which created a mixture inside the tank, where the temperature was uniform across the height, and the apparition of stratification due to the fact of discharge from the bottom of the tank.
Carbon dioxide (CO2) and other greenhouse gases (GHG) are considered the main cause of many environmental issues that lead to climate change and global warming. Carbon Capture and Storage (CCS) is a promising sustainable method used for decreasing CO2 emissions. Nevertheless, for the CCS technology to be effectively put into use, some aspects should be taken into account, namely cost, capacity and durability of storage. In this paper, different CCS methods are described and the work proposes an alternative way of storing CO2 (and energy) using large-scale dry storage of biomass. The main advantage of suggested carbon storage system is that has no operation cost, and no need for maintenance and monitoring. By comparing the present project with other advanced and hi-tech projects, it is concluded that the proposed biomass storage is a cost-effective CCS technique. In the future, when the CO2 emissions are not seen as a global problem, this dry storage method enables recovery of stored wood for various purposes.
Current study concerns the fundamental problems to eliminate pathogens that are responsible for waterborne diseases. These illnesses, which have followed man throughout history, are described by occurring symptoms such as diarrhea and nausea. The various organisms identified within this document as waterborne bacterial pathogens are, e.g., Legionella (causes Pontiac fever), Salmonella (typhoid fever), and Yersinia (plague). Several control methods are available for water disinfection: biocide, ultraviolet light sterilization, copper–silver ionization, ozonation, etc., but only thermal treatment can eliminate bacterial pathogens, which are killed almost instantly at 70 °C. The current chapter describes water disinfection by a solar concentrator combined with a heat recovery system that reduces the heat demand. Though this study is made for a small system (160 l of hot water per day), the system can be enlarged (more hot water and more solar collector area), and the results are thus valid also for such larger systems. Here experiments of water treatment by a solar concentrator are summarized and analyzed where the temperature exceeds 80 °C at the outlet of the heat exchanger.
The basic issue of this thesis concerns one of the fundamental problems of the future of our society: How to meet the energy requirements for a large and growing world population while preserving our environment? This question is important for the world and the answers are complex and interwoven.Conventional energy sources, fossil and fissile, are polluting in the present and in the future: they erode the environment and their resources are limited. Renewable energy (hydro, wind, solar, geothermal) constitutes a minimum of pollution in the different energy systems. The technologies for using renewable energy are well known though further development and progress are made. This development also requires behavioural change, adaptation, and above all political will. The transition from an economy based on fossil energy to an economy based on renewable energy appears necessary for the protection of the environment. The cost of renewable energy is often represented as an obstacle but remains competitive in the long run.The development and availability of renewable energy, which varies because of its spatial and temporal distribution, require an adaptation of lifestyle, habits, habitat design (passive bioclimatic houses), urban planning and transportation.The focus of this thesis was to apply renewable energy in an area with hot summers and cold winter, a climate like that in the northwest of Algeria. In order to provide improved comfort in the buildings and also economic development in this area, the energy demand for heating and cooling was analyzed in the ancient city of Tlemcen. To supply domestic hot water and space heating, water must be simultaneously available at two different temperature levels. Cold water temperature, close to that of the atmosphere, and hot water between 50 and 60°C. An interesting feature of the preparation of hot water is the small variation of requirements during the year, unlike that to heating. The preparation of hot water is one of the preferred applications of solar energy in the building for several reasons. For this reason an experimental study of the thermal behaviour of a domestic hot water storage tank was undertaken. The phenomena that affect the thermal behaviour of tank especially the coupling between the solar collector and storage tank was studied. This study included concentrating solar collector in which optical fibers were used to transport the energy to the storage tank. Another technology was introduced and developed for the heating and cooling of buildings in the desert involving an existing ancient irrigation system called Fouggara. The novel idea is to use the Fouggara as an air conditioner by pumping ambient air through this underground system. Then air at a temperature of about 21°C would be supplied to the building for heating in the winter and cooling in the summer. This study shows the feasibility of using this ancient irrigation system of Fouggara and contributes to reducing and eliminating the energy demand for heating and cooling buildings in the Sahara desert.
The current study concerns the fundamental problems of Legionnaires disease. Four decades after Legionnaires' bacteria was first identified there is still a low level of clinical awareness. Humans are infected by inhalation of aerosolized water and/or soil contaminated with the bacteria. Several control methods are available for water disinfection: biocide, ultraviolet light sterilization, copper-silver ionization, ozonation etc. but only thermal treatment can completely eliminate Legionella, which is killed almost instantly at 70 °C. The current paper describes Legionella disinfection by a solar concentrator combined with a heat recovery system that reduces the heat demand. Though this study is made for a small system (160 l of hot water per day) the system can be enlarged (more hot water and more solar collector area) and the results are thus valid also for such larger systems. Here experiments of water treatment by a solar concentrator are summarized and analyzed where the temperature exceeds 80 °C at the outlet of the heat exchanger.
In order to utilise naturally stored heat or cold from the ground, seasonal temperature variations are required. The reason is that the ground temperature is then warmer than the air temperature during winter and colder during summer. The heating and cooling demand in North Africa varies considerably with the greatest cooling demand in the East and the greatest heating demand in the West. In parts of Algeria the mean temperature difference between the coldest and warmest month is greater than 20 °C, which is favourable. In current work it was shown that the ancient Fouggara system, even today would be interesting for heating and cooling of buildings in the Sahara desert.