Alaa Hawari

A fouling suppression system in submerged membrane bioreactors using dielectrophoretic forces

A novel method was developed to suppress membrane fouling in submerged membrane bioreactors. The method is based on the dielectrophoretic (DEP) motion of particles in an inhomogeneous electrical field. Using a real sample of biomass as feed, the fouling-suppression performance using DEP with different electrical field intensities (60-160 V) and different frequencies (50-1000 Hz) was investigated. The fouling-suppression performance was found to relate closely with the intensity and frequency of the electrical field. A stronger electrical field was found to better recover the filtrate flux. This is because of a stronger DEP force acting on the biomass particles close to the membranes surface. Above an intensity and frequency value of 130 V and 1 kHz, respectively the permeate flux was reduced due to an electrothermal effect.

A comparative study of the treatment of ethylene plant spent caustic by neutralization and classical and advanced oxidation

The treatment of spent caustic produced from an ethylene plant was investigated. In the case of neutralization alone it was found that the maximum removal of sulfide was at pH values below 5.5. The higher percentage removal of sulfides (99% at pH = 1.5) was accompanied with the highest COD removal (88%). For classical oxidation using H2O2 the maximum COD removal percentage reached 89% at pH = 2.5 and at a hydrogen peroxide concentration of 19 mM/L. For the advanced oxidation using Fentons process it was found that the maximum COD removal of 96.5% was achieved at a hydrogen peroxide/ferrous sulfate ratio of (7:1).

Application of dried anaerobic digested sewage sludge as phenol biosorbent

Untreated anaerobically digested sewage sludge was used for the first time as a biosorbent for removing phenol from aqueous solution. Results showed that adsorption capacity was influenced by the pH of the aqueous solution with an observed maximum phenol removal at pH around 6–8. The adsorption equilibrium of phenolic compounds was obtained after almost two hours with an adsorption of approximately 90% of the phenolic compounds. A sorbent concentration of 1.8 g/L was found to insure the best removal percentage and the best sorbent capacity. Both Langmuir and Freundlich models have provided reasonable fittings for the data of phenol adsorption. The experimental data fitted the pseudo-second-order kinetic model and the intraparticle diffusion model. The values of change in Gibbs free energy (ΔG°), enthalpy (ΔH°) and entropy (ΔS°) were calculated. The thermodynamic study of adsorption process showed that the process was exothermic in nature.

Multiattribute Utility Theory Deployment in Sewer Defects Assessment

AbstractAssessing the condition of sewer pipelines is a backbone process to plan for rehabilitation and maintenance work. The closed circuit-television (CCTV) method is the widely adopted method to...

An economic loss model for failure of sewer pipelines

Abstract Estimating the costs of failure for sewer pipelines is usually accompanied with uncertainties because of the difficulty in capturing the relationship between the physical and economical characteristics of failed pipelines. To reduce such uncertainties economic loss models are usually used to evaluate the consequences of failure. This paper presents a methodology to estimate economic loss as a result of sewer pipelines’ failure using cost benefit analysis approach. Costs of sewer pipelines’ failure in addition to costs resulting from avoiding such failures are identified and analysed. To validate the proposed methodology, actual costs from a real failure incident were compared with the proposed model outputs. The model could estimate the direct and indirect costs with a deviation ranging between 10–12% and 22–30%, respectively. By implementing the proposed methodology on two case studies, it was found that the indirect costs as a result of sewer pipelines’ failure represent a significant portion ranging between 89 and 94% of the total costs of failure. Also, it was found that costs related to environment, delays to work and traffic disruptions contribute by 12–35% to the indirect costs.

Forward Osmosis Feasibility and Potential Future Application for Desalination

Abstract Forward Osmosis has been intensively investigated for seawater desalination in the past decade. However, the application of technology is still limited apart from a number of pilot and small commercial plants. Initially, forward osmosis was proposed as a breakthrough in the desalination technologies due to its potential for reducing the power consumption to the thermodynamic seawater limits. Lately, experimental studies have demonstrated that first insights underestimated the technologys energy efficiency and feasibility for desalination. Membrane fouling, back salt diffusion, membrane mechanical strength, draw solution, and many other factors were behind the loss of interest in forward osmosis technology. Conversely, field experiments have shown that forward osmosis membrane fouling was not a major problem, and water flux met the expectation when a full-scale hollow fiber membrane was provided. However, there were insufficient data regarding the cost and energy efficiency of the membrane regeneration stage. For thermal regeneration using a thermolytic draw solution, the major concerns were the ease of application and residual draw solution in the feed solution. The current study addresses the pros and cons of forward osmosis and the primary reason behind the technology being less successful, despite the large amount of money and efforts invested over the past decade.

Determining Relative Weights of Sewer Pipelines’ Components and Defects

AbstractCondition assessment models for sewer network components can be considered a tool for key personnel to make informed decisions regarding the required interventions on the basis of the curre...

Condition assessment model for sewer pipelines using fuzzy-based evidential reasoning

Abstract A condition assessment model for gravity and pressurised sewer pipelines using Fuzzy Set Theory (FST), and Evidential Reasoning (ER) with the aid of Fuzzy Analytical Network Process (FANP) integrated with Monte-Carlo Simulation is presented in this paper. Seventeen factors were considered for gravity pipelines in addition to the operating pressure for pressurised pipelines. The model was developed using relative weights for the different factors affecting pipelines condition which were obtained using FANP integrated with Monte-Carlo Simulation based on the results of a questionnaire that was distributed to experts working in the field of infrastructures. FST was used to set thresholds for the different effect values of factors on the pipelines’ condition, whereas ER was used to determine the final condition assessment index for the pipeline by aggregating both the relative weights and effect values for the different affecting factors.

Simulation-Based Condition Assessment Model for Sewer Pipelines

AbstractCondition assessment models are considered as an evaluation tool that can be used by decision makers to accurately evaluate and assess the condition of pipes. Condition assessment of pipes helps in reaching better decisions in terms of repair or replacement before their failures. This paper presents a condition assessment model developed for gravity and pressurized pipelines in sewer networks using integrated fuzzy analytical network process (FANP) and Monte Carlo simulation techniques. Factors affecting gravity and pressurized pipelines in sewage networks were studied and included in the developed model. A questionnaire was distributed to experts in the field, to determine the weights of 17 factors for gravity pipelines, in addition to the operating pressure for pressurized pipelines. The developed model uses a weighted scoring system to determine a numerical value indicating the condition of pipelines. FANP was used to determine the weights of the factors affecting pipeline assessment, while Mon...

Fuzzy Logic-Based Model to Predict the Impact of Flow Rate and Turbidity on the Performance of Multimedia Filters

AbstractThis paper uses fuzzy logic–based models to predict and evaluate the performance of multimedia filters utilized in wastewater treatment. A fuzzy logic–based model is constructed and trained...