| The Colorado River is the most important source of water in southern California which typically contains high total dissolved solids (TDS) of more than 700 mg/L. The Metropolitan Water District of Southern California (MWDSC) identified reverse osmosis as the best available technology for desalination of the water for reducing the TDS level.; In the first phase of the study, a series of completely mixed batch reactor (CMBR) studies were conducted to determine the effect of various environmental parameters including pH, temperature, and carbon-to-sulfur (C/S) on the desulfurization process. Subsequently, a series of chemostat experiments were carried out to determine the biokinetic parameters. These parameters further used as input for the mathematical model developed for the desulfurization process. Furthermore, fluidized bed bioadsorber reactor studies were conducted to evaluate the process performance as a function of several variables including the influent sulfate concentration, C/S ratio, and pH. The process performance was evaluated at different influent sulfate concentrations of 600, 700, 800, 900, 1000, and 1100 mg/L, different pHs of 6.5, 7.0, and 7.5, and different C/S ratios of 0.8, 1.0, and 1.2. Sulfate reduction and removal efficiencies as high as 86-91% were achieved at an influent sulfate concentration of 1100 mg/L. Later, the fluidized bed bioadsorber reactor (FBBR)-sand process performance was investigated and compared with those using granular activated carbon (GAC). The general observation was that GAC performed significantly better than sand. Nonetheless, the superiority of GAC would even be more apparent, should the brine concentrate contain heavy metals and organic constituents that would potentially inhibit microbial activity.; The next phase of the research included the simulation of the chemostat process dynamics and performance of model sensitivity analyses to identify the various key parameters that have a significant influence on the system operation and subsequently on the FBBR process, and to evaluate the biokinetic parameters that would eventually be employed as input parameters in the FBBR model. The chemostat simulation studies demonstrated good agreement between the experimental data and the chemostat model predictions. Sensitivity analyses of the chemostat model indicated that maximum specific growth rate, mu m and half-velocity constant, Ks had the geartest influence on chemostat dynamics with reference to sulfate reduction and carbon source (ethanol) utilization.; The next phase involved the development of a mathematical model for predicting the FBBR process dynamics. Model calibration was based on biological and transport parameters determined from independent laboratory experiments and/or correlation techniques. The model was verified and validated for different process variables.; In the last phase of this study, process design and upscaling strategies were developed, and the significance of the relevant non-dimensional groups identified besides their relative contribution to the overall process dynamics. Model simulation studies were performed to predict the FBBR dynamics under different process and operating conditions, and to determine the sensitivity of process dynamics to various biokinetic parameters. Sensitivity analyses demonstrated that the maximum specific growth rate, mum and half-velocity constant, Ks had the most profound influence on the process dynamics with reference to sulfate reduction and ethanol utilization.; The results of this study demonstrated that the FBBR system represents a reliable, efficient, and cost effective technology for removing sulfate from the reverse osmosis brine concentrate. It was found that the FBBR system using GAC was significantly more efficient than the FBBR-sand system. However, the latter process required lower hydraulic retention time, and therefore, entails smaller reactor and lower energy costs. The FBBR model successfully predicted the p... |
