Raafat Alnaizy

Draw solute recovery by metathesis precipitation in forward osmosis desalination.

ABSTRACT Forward osmosis (FO) is a natural osmosis process that is under investigation as a potential means of desalination, wastewater treatment, and energy production. This article presents forward osmosis desalination study on a commercial cellulose acetate membrane. The membrane was tested for high feed concentrations ranging from typical brackish water concentration to seawater concentration. For energy-efficient recovery of product water, a 240,000 ppm of MgSO4 draw solution was used. The membrane achieved an average water flux of 4.06 and 0.60 L/m2 h in case of brackish and seawater, respectively. Pure product water with a salt content of 350 ppm was recovered from the diluted MgSO4 draw solution by reaction with stoichiometric amount of barium hydroxide to remove the soluble draw solute as magnesium hydroxide and barium sulfate precipitates.

Environmental science and pollution sensing, monitoring, modeling, and remediation

This special issue of Environmental Science and Pollution Research highlights selected papers presented at the Second International Conference on Water, Energy, and Environment (ICWEE 2013) which was held on September 21–24, 2013 in Kusadasi, Turkey, and organized by Izmir Katip Celebi University (IKCU) in Turkey, American University of Sharjah (AUS), and United Arab Emirates University (UAEU) in UAE. This special issue covers the topics of environmental quality measurements, contamination, detection, remediation, and prevention, as well as the management, monitoring, and modeling The ICWEE 2013 was a high-level international conference emerging as one of the best platforms for academic exchange, potential cooperation opportunities, and accelerating the transformation and promotion of achievements; it provided a forum for researchers as well as practitioners to address recent research results and to discuss various technical issues in top three problems of next 50 years, namely energy, water, and environment. Additionally, a number of leading practitioners, policy makers, and researchers were invited to deliver keynote lectures. The ICWEE program included peer-reviewed technical program, short courses, posters, and panel sessions, industrial presentations, and exhibition based upon, the following themes:

Neural Network Model Identification and Advanced Control of a Membrane Biological Reactor

System identification with different input-output structures, for a membrane biological reactor (MBR), was performed using artificial neural networks (ANN) black-box modeling. The ANN models were able to capture the dynamic flux experimental literature data. Sensitivity analyses were applied on the ANN models to quantify the effects of variation in the process inputs (backwash pressure, vacuum pressure, backwash and vacuum time) on the process output (flux rate. Sensitivity analysis was applied on the developed NN in order to find the optimum backwash scheduling. The maximum flux was attained at around 165 (L/m 2 ·day) that corresponded to an optimum vacuum-to-backwash time ratio of 10 minutes vacuum to 2 minutes backwash. Advanced control strategy using neuro-model predictive control (NN-MPC) methodology was applied to control the MBR system. The NN-MPC parameters were tuned to attain an optimum performance. The NN-MPC was efficient in tracking the flux set-point changes by adjusting vacuum-to-backwash time ratio within the operation constraints

Modeling and dynamic analysis of a membrane bioreactor with backwash scheduling

Abstract A dynamic model, based on mass transport and reaction rate laws of biomass and substrate for a membrane bioreactor (MBR), was successfully developed. Furthermore, an empirical model for flux prediction was used. Key kinetic model parameters were estimated via nonlinear fitting of the model predictions to experimental data obtained from current and previous works. The performance of the MBR was evaluated with different vacuum-to-backwash time ratio. Permeate flux dynamics were shown to be sensitive to the backwash scheduling scenario. The proposed model will enable optimization of MBR operation in an attempt to minimize membrane fouling.

Analysis of Water Evaporation and Drift Losses During Irrigation in Semi-arid Areas of Sharjah (UAE) and Riyadh (KSA)

Water evaporation and wind drift losses mainly depend on air relative humidity, air and water temperature, drop size, and wind speed. Evaporation and drift loss during water application by means of sprinkle irrigation was studied in the Emirate of Sharjah, United Arab Emirates (UAE) and Riyadh, Saudi Arabia. Results for both cities did not vary substantially due to high relative humidity even under high air temperature. Results indicated that evaporation losses are usually <5% under any climatological conditions in the two Gulf cities. For nighttime watering to be considered, extra-costs (e.g., electricity, manpower) should not exceed potential savings.