159 research outputs found
Condition Assessment Models for Sewer Pipelines
No full textUnderground pipeline system is a complex infrastructure system that has significant impact on social, environmental and economic aspects. Sewer pipeline networks are considered to be an extremely expensive asset. This study aims to develop condition assessment models for sewer pipeline networks. Seventeen factors affecting the condition of sewer network were considered for gravity pipelines in addition to the operating pressure for pressurized pipelines. Two different methodologies were adopted for models’ development. The first method by using an integrated Fuzzy Analytic Network Process (FANP) and Monte-Carlo simulation and the second method by using FANP, fuzzy set theory (FST) and Evidential Reasoning (ER). The models’ output is the assessed pipeline condition. In order to collect the necessary data for developing the models, questionnaires were distributed among experts in sewer pipelines in the state of Qatar. In addition, actual data for an existing sewage network in the state of Qatar was used to validate the models’ outputs. The “Ground Disturbance” factor was found to be the most influential factor followed by the “Location” factor with a weight of 10.6% and 9.3% for pipelines under gravity and 8.8% and 8.6% for pipelines under pressure, respectively. On the other hand, the least affecting factor was the “Length” followed by “Diameter” with weights of 2.2% and 2.5% for pipelines under gravity and 2.5% and 2.6% for pipelines under pressure. The developed models were able to satisfactorily assess the conditions of deteriorating sewer pipelines with an average validity of approximately 85% for the first approach and 86% for the second approach. The developed models are expected to be a useful tool for decision makers to properly plan for their inspections and provide effective rehabilitation of sewer networks.1)- NPRP grant # (NPRP6-357-2-150) from the QatarNational Research Fund (Member of Qatar Foundation)
2)-Tarek Zayed, Professor of Civil Engineeringat Concordia University for his support in the analysis part, the Public Works
3)-Authority of Qatar (ASHGAL) for their support in the data collection
MXENE BASED NANOCOMPOSITES FOR HIGH PERFORMANCE CAPACITIVE DEIONIZATION
No full textMXene is considered as a superior electrode material for capacitive deionization (CDI) due to its high conductivity and two-dimensional structure. However, the electrochemical performance of pristine MXene nanosheets has been significantly impeded by the surface oxidation in the aqueous media and re-stacking caused by van der Waals forces which reduces the ions storage capacity. Also, niobium based MXenes (Nb2CTx and Nb4C3Tx) have never been studied as an electrode material for CDI. In this dissertation, we improved the performance and antioxidation properties of Ti3C2Tx MXene and studied different type of MXene as an electrode material for hybrid capacitive deionization (HCDI). In the first part of the dissertation, the chitosan-lignosulfonate/Ti3C2Tx MXene (CLM) composite was used as a binder-free electrode to enhance the ion storage capacity and long-run cycling stability for HCDI. The chitosan-lignosulfonate nanospheres were able to increase the interlayer spacing between the MXene nanosheets effectively, which has significantly enhanced the ion storage capacity and electrochemical properties of the electrode. The binder-free CLM cathode demonstrated a high salt adsorption capacity of 44.6 mg g-1 and a maximum average salt adsorption rate of 5.8 mg g-1 min-1 at 1.2 V. A high cycling stability above 97% for 30 cycles was observed. Also, the long-term stability of CLM electrode was studied by X-ray photoelectron spectroscopy (XPS) and the results showed that the CLM electrode was not prone to surface oxidation after 30 cycles. In the second part of the study, the multilayered Nb2CTx (ML-Nb2CTx) and delaminated Nb2CTx (DL-Nb2CTx) MXene were used as cathode electrodes in HCDI. The material characterized using SEM, TEM, and XRD techniques, confirmed well delamination of Nb2CTx. DL-Nb2CTx electrode showed higher SAC and SAR by 61% and 67%, respectively, when compared to ML-Nb2CTx electrode. In the third part of the study, multilayered Nb4C3Tx (ML- Nb4C3Tx) and delaminated Nb4C3Tx (DL-Nb4C3Tx) MXene were used as a cathode electrode for HCDI. DL-Nb4C3Tx electrode demonstrated a higher specific capacitance when compared to ML-Nb4C3Tx electrode, reaching a value of 179 F/g at 1 A/g, indicative of excellent electrochemical properties. Also, DL-Nb4C3Tx showed the highest SAC (22.1 mg g-1) and SAR (2.07 mg g-1 min-1) when it is compared to Nb2CTx and Ti3C2Tx electrodes at 1.2V
Engineering A Fertilizing Draw Solution For Irrigation Using Forward Osmosis / Reverse Osmosis Hybrid System
No full textLarge volumes of fresh water are consumed in the human’s daily activities,
producing large volumes of highly contaminated wastewater which exhibits a major
environmental problem. Wastewater is treated using multiple technologies to produce
Treated sewage effluent (TSE) which is considered to be less contaminated but
unusable by human daily activities.
This work investigates the application of a hybrid system that combines forward
osmosis (FO) and reverse osmosis (RO) processes for the supply of a fertilizing solution
that could be used directly for irrigation purposes. In the forward osmosis process,
treated sewage effluent (TSE) is used as the feed solution and two different types of
draw solutions were investigated namely, 0.5M NaCl solution and 0.5M NaCl and
0.01M diammonium phosphate ((NH4)2HPO4) solution. The impact of the feed
solution and the draw solution flowrates and the membrane orientation on the
membrane flux were investigated in the forward osmosis process. In the reverse
osmosis process, seawater RO membrane (SW30HR) and brackish water RO
membrane (BW30LE) were tested for the regeneration of the draw solution. In the
forward osmosis process, it was found that the highest membrane flux was 13.2 LMH
achieved at a flow rate of 2 LPM for the feed solution and the draw solution and when the 0.5M NaCl and 0.01M diammonium phosphate solution was used as the draw
solution in the FO mode membrane orientation. The FO process had high rejection rates
for total phosphorus and ammonium which were 99% and 97%, respectively. Reverse
osmosis achieved 99% total salts rejection rate using the seawater RO membrane. The
final product water had high quality in terms of total dissolved solids and nutrients
concentration. The final product meets the irrigation water quality
Treatment of produced water using an enhanced electrocoagulation process
No full textProduced water generated during oilfield processes is considered as a major problem that requires solving due to its high salinity and pollutant contents. Electrocoagulation is one of the promising processes for produced water treatment. In this study, steel slag was used as an additional coagulant in the electrocoagulation process for the produced water treatment. The impact of current density, reaction time and the amount of added steel slag were investigated. For a current density of 10 mA/cm2 at a 10 minute reaction time, it was found that the slag sample had a total suspended solids removal of 90% compared to 55.7% for the pure sample. As for the turbidity, the slag sample showed an 85.9% removal, and the pure sample showed an 80.1% removal. The oil and grease removal percentage were almost the same for the sample with and without the slag at 98.9% removal. For the reaction time, it was found that as the reaction time increases the percentage removal for the total suspended solids and turbidity increases to a certain extent. The optimum removal percentage was obtained at a reaction time of 30 minutes. It was found that the slag sample had a 94.8% and a 92.5% total suspended solids and turbidity removal percentages, respectively, while the pure sample had a lower removal percentage of 90% and 90.3%, respectively. The oil and grease removal percentage were similar for both samples where it was 98.6% for the slag sample, and 98.9% for the pure sample. The impact of the amount of added slag was studied for 3 different concentration: 5g/L, 10g/L, and 15g/L. It was found that the optimum removal percentage of suspended solids, turbidity, and oil and grease were 83%, 55%, 96.5%, respectively, using a slag weight of 5 grams
A NON-DESTRUCTIVE METHODOLOGY FOR LEAK DETECTION IN WATER NETWORKS USING INFRARED PHOTOGRAPHY (IR) AND GROUND PENETRATING RADAR (GPR)
No full textTwo noninvasive and nondestructive methodologies for detecting leaks in water pipes were proposed and tested. The first method combines the use of Ground Penetrating Radar (GPR) for accurate determination of pipe location, followed by infrared (IR) thermographic imaging for determining the leak location. In IR thermography, four operating conditions (varying camera height and speed) were tested. Results were statistically analyzed using analysis of variance (ANOVA) and pairwise comparison methods. Several factors were found to affect the accuracy of the proposed methodology in predicting the leak location, namely, the characteristics of the studied surface (i.e. emissivity), the characteristics of the surrounding environment (i.e. ambient temperature and relative humidity), and the operating conditions of the IR camera (i.e. speed and height of the camera). In the case of low emissive surfaces, a slower camera speed would be required for the camera to be able to capture the thermal contrast at the real leak location. The results obtained in this study have also shown that under high ambient temperatures and high relative humidity conditions, a higher speed of the IR camera would reduce the impact of noise on the collected thermal contrast and therefore, would give better leak location prediction results. The field of view (FOV) is affected by the camera’s height from the surface. At lower heights, less area will be covered per frame; therefore, a more homogenous temperature distribution per frame will be obtained. Consequently, the contrast between the different frames will be higher and better leak predictions would be expected. The tested methodology proved the flexibility of the approach and the ability of accurately predicting the leak location under different conditions. In method two: the GPR alone was used to predict the existence and location of a leak in a water pipe. GPR data processing was performed based on the refined radargram, resulting in promising outcomes in the applicability of the method.Qatar National Research Fund (QNRF) for funding this research (NPRP-5-165-2-055)
Fabrication of Fouling Resistant Ti3C2Tx(MXene) Cellulose Acetate Nanocomposite Membrane for Forward Osmosis Application
No full textForward Osmosis (FO) is one of the promising technologies that can be used to combat growing water scarcity. However, FO membrane fouling hinders the widespread application of this technology by significantly reducing the water flux and membrane lifecycle. Although forward osmosis has shown lower membrane fouling when compared to other membrane technologies, forward osmosis membrane resistance to fouling must still be improved. In this study, Ti3C2Tx (MXene) was used to improve the fouling resistance of FO flat-thin film membranes. The mixed-matrix Ti3C2Tx (MXene)/ cellulose acetate (CA) membranes with different (wt%) loading of MXene were fabricated by covalent crosslinking followed by phase inversion method. The fabricated membranes were characterized by X-ray powder diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), contact angle measurement and scanning electron microscopy (SEM). The performance of the fabricated FO membranes was evaluated utilizing seawater as draw solution (DS) and two feed solutions (FS) namely; distilled water (DI) and treated sewage effluent (TSE). The water flux, reverse solute flux and the rejection of dissolved solids were evaluated in the FO process. It was observed that the cross-linked cellulose acetate membrane with 8 wt% MXene (CCAM-8%) showed higher resistance to fouling when compared with commercial thin-filmcomposite (TFC) FO membrane, the water flux of CCAM-8% decreased by only 10.7% using TSE as FS compared to DI, where the water flux of the TFC commercial membrane decreased by 32.2% when using TSE as FS compared to DI
HARVESTING OF CHLORELLA SP. MICROALGAE BY DIELECTROPHORETIC FORCE USING TITANIUM DIOXIDE (TiO2) INSULATED ELECTRODES
No full textThe harvesting of microalgae using conventional technologies suffers from biomass contamination, high energy consumption and long processing time. In this study, titanium dioxide (TiO2) insulated stainless steel electrodes were used for the harvesting of Chlorella sp. microalgae by dielectrophoretic force. The new electrode configuration is expected to achieve high harvesting efficiency with zero contamination for the harvested biomass. The effect of various experimental parameters on the harvesting efficiency were evaluated using a bench scale setup. This includes settling time, applied voltage, interelectrode distance, application of pulsed electric field, and applied current frequency. The maximum harvesting efficiency of 76.6% was obtained at 4 mm interelectrode distance, 200 V applied voltage, 250 kHz frequency, and application of pulsed electric field for 30 minutes. Under these conditions, the energy consumption was 7.76 kWh/kg. The most significant impact of using the new electrode configuration is achieving high harvesting efficiency with no contamination for the biomass
Treatment Of Dewatering Construction Water Using An Integrated Forward Osmosis System
No full textForward osmosis (FO) has gained substantial research attention in recent years as a new emerging water treatment technology with low energy consumption. In this study, forward osmosis has been used to treat dewatering construction water (DCW). The impact of flow rates of feed solution (FS) and draw solution (DS), the placement of a spacer on the support layer of the FO membrane and the pretreatment of the feed solution on the performance of the forward osmosis process were investigated. It was found that a feed solution and draw solution flow rate of 2.9 LPM gave the highest membrane flux with an initial value of 0.055 L/m2.min compared to 0.048 L/m2.min, 0.048 L/m2.min and 0.044 L/m2.min at the flow rates of 2.2 LPM, 1.5 LPM and 0.8 LPM, respectively. The highest recovery rate of 24% was obtained at a flow rate of 2.2 LPM compared to a recovery rate of 16%, 21% and 15% for flow rates of 2.9 LPM, 1.5 LPM and 0.8 LPM, respectively. The influence of pretreating DCW on the performance of the FO process was also investigated. Pretreatment by primary settling and multimedia filtration were carried out. Results showed that the recovery rate of the FO process increased the most after pretreatment by multimedia filtration with a recovery rate of 30% compared to 22% and 15% for pretreatment by settling and without treatment, respectively. Furthermore, it was found that when the membrane’s active layer was facing the draw solution in (DS-AL) operation mode, a better membrane flux was achieved when compared to the membrane’s active layer facing the feed solution (FS-AL)
TOWARDS SUSTAINABLE MUNICIPAL WASTEWATER REUSE IN IRRIGATION OF FOOD CROPS BY UTILIZATION OF HYBRID MEMBRANE PROCESS AND MAGNETIC NANOPARTICLES
No full textWastewater reuse could relieve the global water scarcity issue when applied in the agriculture industry however, the wastewater shall be treated to ensure that the water quality meets the irrigation water quality. In this dissertation, we suggested sustainable solutions for municipal wastewater reuse in irrigation of food crops by utilization of hybrid membrane process and magnetic nanoparticles. In the first part of the dissertation, the public perception for wastewater reuse in Qatar was analyzed and a framework was designed to support decision makers when implementing the technology and achieve high acceptance from the public. Almost 20% of the participants agreed to use treated wastewater for irrigation of food crops. A significant relationship was observed between level of acceptance and age, monthly income and number of children. In the second part of the study, we analyzed and optimize the performance of highly mature membrane technologies such as nanofiltration and reverse osmosis for the reclamation of treated sewage effluent to be used in irrigation of food crops. It was found that nanofiltration is not suitable for the reclamation of wastewater due to its low rejection rate for monovalent ions. In reverse osmosis, the permeate water quality was suitable for irrigation of food crops and the highest recovery rate was 36%. Although reverse osmosis was suitable for the reclamation of treated sewage effluent, the wide implementation is hampered by membrane fouling. In the third part of the study, we designed a full scale forward osmosis plant for the reclamation of treated sewage effluent which was used to dilute reverse osmosis brine. It was found that the specific energy consumption of the forward osmosis process was 0.18 kWh/m3. The diluted brine can be regenerated using reverse osmosis and used as irrigation water for food crops. In the fourth part of the study, a novel Polyamidoamine dendrimer coated magnetic nanoparticle was synthesized to be used as draw solute in the forward osmosis process. The performance of the synthesized magnetic nanoparticles as draw solute was evaluated using a bench scale forward osmosis setup. The average water flux obtained was 12.9 LMH during the first running cycle and decreased with time due to the dilution of draw solution. The magnetic nanoparticles were easily recovered using a permanent magnet and reused as draw solute for multiple cycles
Automated Defect Detection Tool For Sewer Pipelines
No full textIn sewer networks, the economic effects and costs that result from a pipeline break are rising sharply. In Qatar, majority of the sewer network pipelines were installed in the last 20 years and are currently in poor condition and constantly deteriorating. As a result, there is huge demand for inspection and rehabilitation of sewer pipelines. In addition to being inaccurate, current Practices of sewer pipelines inspection are time consuming and may not keep up with the deterioration rate of the pipelines. Consequently, this research aims to develop an automated tool to detect different defects such as cracks, deformation, settled deposits and joint displacement in sewer pipelines. The automated approach is dependent upon using image-processing techniques and several mathematical formulas to analyze output data from CCTV camera photos. Given that one inspection session can result in hundreds of CCTV Camera footage, introducing an automated tool would help yield faster results. Additionally, given the subjective nature of most defects, it will result in more systematic results since the current method rely heavily on the operator's experience. The automated tool was able to successfully detect cracks, displaced joints, ovality and settled deposits in pipelines using CCTV Camera inspection output footage. Using two different data sets, the constructed Matlab code could successfully differentiate between cracks and displaced joints with an overall crack detection success rate of 84% and an overall displaced joint detection rate of 94%. The code was also able to efficiently detect settled deposits in the pipelines with a detection rate of 90%. In addition, the automated ovality detection resulted in 100% compatibility with the manual circularity detection
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