Development Of A Model-Based Decision Support System For Water Treatment In Smart Micro Water Grid

Micro water grid (MWG) is an emerging concept for decentralized water management system for residential, industrial, commercial, and institutional buildings. MWG achieves specific local goals, such as reliability, diversification of water sources, and cost reduction. Unlike micro electricity grid, MWG has not been well-established, leading to a problem of initial design and operation. Thus, a MWG system requires a “smart” infrastructure that allows autonomous control and regulation. In this study, a decision support system (DSS) was designed to select optimum combinations of water treatment unit processes in MWG. To begin, key questions on water treatment in MWG systems were identified. Then, the knowledge-based system was developed based on the inputs from experts in related research fields and the prediction of treatment efficiency from theoretical model. A series of experiments were carried out to obtain the model parameters for each unit process (i.e. media filtration, microfiltration, GAC, nanofiltration, chlorination, UV). The flow chart for decision making was created and revised upon considering virtually all possible situations in MWG. As the final step, a web-based system was developed and implemented. Although it is a first version of DSS for MWG, it has potential for an increase in the efficiency of water treatment under various situations. ACKNOWLEDGEMNET This research was supported by a grant (12-TI-C01) from Advanced Water Management Research Program funded by Ministry of Land, Infrastructure and Transport of Korean government

Optimized Use Of Water From Multiple Sources In Micro Water Grid Systems: A Modeling Approach

Micro water grid (MWG) is a novel approach to allow high reliability, diversification of water sources, low energy consumption, and cost reduction. Although it is not well-defined, it has potential for efficient management of urban water. MWG is suitable for use in small-scale buildings and towns, which have various uses of water produced from multiple source waters. Accordingly, design of MWG is challenging without proper tools to predict its performance. This research focused on the development and application of a model for optimized use of water from multiple sources in MWG systems. The model was comprised of two modules including strategy identification and mass balance calculator. The former assists in identifying strategy under the given natural and infrastructural conditions. The latter helps to determine water demand/supply and dimension of the water treatment system. Water from various sources including tap water, ground water, rainwater, reclaimed water, and desalinated water was considered in the model. The model and its graphic user interface (GUI) were built under the Matlab environment. Results show that the simulation model was found to be effective to optimize the performance of MWG. Based on the sensitivity analysis of the model, factors affecting the effectiveness of MWG could be identified. Moreover, this model was applied to design a pilot-scale MWG system in a building, predict its water quantity and water quality, and estimate the specific energy consumption. ACKNOWLEDGEMNET This research was supported by a grant (12-TI-C01) from Advanced Water Management Research Program funded by Ministry of Land, Infrastructure and Transport of Korean government

Analysis of Polyvinylidene Fluoride Membranes Fabricated for Membrane Distillation

The optimization of the properties for MD membranes is challenging due to the trade-off between water productivity and wetting tendency. Herein, this study presents a novel methodology to examine the properties of MD membranes. Seven polyvinylidene fluoride (PVDF) membranes were synthesized under different conditions by the phase inversion method and characterized to measure flux, rejection, contact angle (CA), liquid entry pressure (LEP), and pore sizes. Then, water vapor permeability (Bw), salt leakage ratio (Lw), and fiber radius (Rf) were calculated for the in-depth analysis. Results showed that the water vapor permeability and salt leakage ratio of the prepared membranes ranged from 7.76 × 10−8 s/m to 20.19 × 10−8 s/m and from 0.0020 to 0.0151, respectively. The Rf calculated using the Purcell model was in the range from 0.598 μm to 1.690 μm. Since the Rf was relatively small, the prepared membranes can have high LEP (more than 1.13 bar) even at low CA (less than 90.8°). The trade-off relations between the water vapor permeability and the other properties could be confirmed from the results of the prepared membranes. Based on these results, the properties of an efficient MD membrane were suggested as a guideline for the membrane development

Economic Evaluation of a Hybrid Desalination System Combining Forward and Reverse Osmosis

This study seeks to evaluate the performance and economic feasibility of the forward osmosis (FO)–reverse osmosis (RO) hybrid process; to propose a guideline by which this hybrid process might be more price-competitive in the field. A solution-diffusion model modified with film theory was applied to analyze the effects of concentration polarization, water, and salt transport coefficient on flux, recovery, seawater concentration, and treated wastewater of the FO process of an FO-RO hybrid system. A simple cost model was applied to analyze the effects of flux; recovery of the FO process; energy; and membrane cost on the FO-RO hybrid process. The simulation results showed that the water transport coefficient and internal concentration polarization resistance are very important factors that affect performance in the FO process; however; the effect of the salt transport coefficient does not seem to be large. It was also found that the flux and recovery of the FO process, the FO membrane, and the electricity cost are very important factors that influence the water cost of an FO-RO hybrid system. This hybrid system can be price-competitive with RO systems when its recovery rate is very high, the flux and the membrane cost of the FO are similar to those of the RO, and the electricity cost is expensive. The most important thing in commercializing the FO process is enhancing performance (e.g.; flux and the recovery of FO membranes)