Rehabilitation in Intermittent Water Distribution Networks for Optimal Operation

Equitable distribution of water is a growing source of worry, and concerns water systems’ managers as water-stressed areas steadily increase and situations of water scarcity are becoming more frequent. The problem goes beyond just the water sector and globally affects many countries’ economies since water resources have multiple uses (i.e., power generation, irrigation, etc.). One of the various strategies to overcome periods of extreme events (e.g., water scarcity) is the adoption of intermittent operation. Intermittent operation can minimize water losses, and manages to supply the same water demand (in terms of volume) during a reduced period of time. However, despite minimizing water losses, the energy consumption necessary to cope with the increased flows and head loss, due to the reduced number of operating hours, increases. This paper explores a strategy based on rehabilitation of the system’s main pipes. It also considers optimal selection and scheduling of pumps aiming at improving the system’s hydraulic parameters (e.g., velocity and head losses) and at reducing the operating costs. Both selection and scheduling of pumps and resizing of main pipes are optimized using Particle Swarm Optimization. The obtained results show that this strategy can significantly reduce the energy consumed and can be economically feasible.

Operation Design of Reaction Crystallization Using Homogeneity Evaluation for the Quality Improvement of Agglomerated Crystalline Particles

In the quality control of crystalline particles, the uniformity of the distribution of each characteristic, such as size and shape, is important. In particular, the problem in reaction crystallization is that the comprehensive uniformity of characteristic distributions is frequently reduced by the agglomeration phenomena. In this study, we designed an operation method to improve the comprehensive uniformity in a liquid–liquid reaction crystallization by evaluating the dynamic variation in the uniformity of particle size and crystal shape using homogeneity. The homogeneity of final particles increased when the supersaturation was lowered by intermittent operation with inner seed production. Since the ratios of the uniformities of particle sizes and crystal shapes constituting homogeneity varied dynamically, the intermittent operation was designed by focusing on individual uniformities. The uniformity of particle size for the final particles was increased via modulation operation using reverse addition for the dissolution of the microparticles. In the growth stage after the reverse addition, the uniformity of the shape of the final particles was increased by raising the number of times of adding solution for decreasing the supersaturation. In addition, we proposed suitable addition methods to improve comprehensive uniformity by controlling uniformity constituting homogeneity at each stage of intermittent operation.