Yes / The removal of pollutants such as N-nitrosamine present in drinking and reuse water resources is of significant interest for health and safety professionals. Reverse osmosis (RO) is one of the most promising and efficient methodologies for removing such harmful organic compounds from wastewater. Having said this, the literature confirms that the multi-stage RO process with retentate reprocessing design has not yet achieved an effective removal of N-nitrosodimethylamine-D6 (NDMA) from wastewater. This research emphasizes on this particular challenge and aims to explore several conceptual designs of multi-stage RO processes for NDMA rejection considering model-based techniques and compute the total recovery rate and energy consumption for different configurations of retentate reprocessing techniques. In this research, the permeate reprocessing design methodology is proposed to increase the process efficiency. An extensive simulation analysis is carried out using high NDMA concentration to evaluate the performance of each configuration under similar operational conditions, thus providing a deep insight on the performance of the multi-stage RO permeate reprocessing predictive design. Furthermore, an optimisation analysis is carried out on the final design to optimise the process with a high NDMA rejection performance and the practical recovery rate by manipulating the operating conditions of the plant within specified constraints bounds. The results show a superior removal of NDMA from wastewater.

Yes / The need for desalinated seawater and reclaimed wastewater is increasing rapidly with the rising demands for drinkable water required for the world with continuously growing population. Reverse Osmosis (RO) processes are now among the most promising technologies used to remove chemicals from industrial effluents. N-nitrosamine compounds and especially N-nitrosodimethylamine (NDMA) are human carcinogens and can be found in industrial effluents of many industries. Particularly, NDMA is one of the by-products of disinfection process of secondary-treated wastewater effluent with chloramines, chlorines, and ozone (inhibitors). However, multi-stage RO processes with permeate reprocessing and recycling has not yet been considered for the removal of N-nitrosodimethylamine from wastewater. This research therefore, begins by investigating a number of multi-stage RO processes with permeate-reprocessing to remove N-nitrosodimethylamine (NDMA) from wastewater and finds the best configuration in terms of rejection, recovery and energy consumption via optimisation. For the first time we have applied Species Conserving Genetic Algorithm (SCGA) in optimising RO process conditions for wastewater treatment. Finally, permeate recycling is added to the best configuration and its performance is evaluated as a function of the amount of permeate being recycled via simulation. For this purpose, a mathematical model is developed based on the solution diffusion model, which is used for both optimisation and simulation. A number of model parameters have been estimated using experimental data of Fujioka et al. (Journal of Membrane Science 454 (2014) 212–219), so that the model can be used for simulation and optimisation with high accuracy and confidence.

The Reverse Osmosis (RO) process has been considered to be one of the most widely utilised techniques for brackish water desalination for its capabilities to produce high-quality water. The RO process characterised by its low energy consumption compared to thermal distillation processes, leading to reduced overall water production cost. To systematically understand the transport phenomena of solvent and solutes via the membrane texture, several mathematical models were developed. This interestingly aids to conduct a huge amount of simulation and optimisation studies to judge the influence of control variables on the performance indexes and to adjust the key variables at optimum values to realise optimum production indexes. In this research, a specific accurate model for a single spiral wound RO process has been successfully developed and used to build accurate models for the multistage brackish water RO desalination process of two different designs. The robustness of the model developed was confirmed via validation against the experimental data collected from simple design of RO system and complicated design of RO system of Arab Potash Company (APC). This is followed by a thorough simulation of the RO process to explore the influence of operating conditions on the process performance indicators. Recently, several contributions were made in this thesis that specifically comprises the improvement of the original design of brackish water RO desalination process. The influence of a retentate recycle design is investigated on the process performance. Moreover, evaluation and minimisation of specific energy consumption (expressed in kWh/m3 of freshwater production) is carried out on the simple and complicated designs of RO process by implementing an energy recovery device. Also, the most suitable brand of membranes was explored for the RO system from a set of different brands of membrane to attain the highest-performance rejection at lowest energy consumption compared to the original membrane. Furthermore, a single optimisation framework was developed to mitigate the specific energy consumption of simple and complicated designs of brackish water RO desalination process. Finally, a thermodynamic limitations and exergy analysis of the complicated design of RO system are outlined via a thoroughly study to investigate the locations of high exergy destruction. These contributions were verified as they promoted the separation performance at a significant energy saving. / Mutah University, Jordan