(412a) A Novel Approach and System for Rapid Field Evaluation of Water Desalination

Reverse osmosis (RO) membrane desalination has emerged as one of the leading methods for water desalination due to the low cost and energy efficiency of the process. Lack of fresh water sources has necessitated further development of these desalination plants, especially in areas with dry climates. Traditionally, field evaluation of a prospective desalination site is a costly and time consuming process. Accomplishing the necessary tasks (verification of feed pretreatment, antiscalant dosing, limiting recovery, etc.) in a more cost-effective and efficient way is necessary. In this presentation, a systematic approach to location-specific field evaluation of the technical viability of reverse osmosis desalination is proposed and demonstrated using a unique mini-modular-mobile (M3) RO system interfaced with an ex-situ scale observation detector (EXSOD). Initially, the EXSOD is used to systematically assess membrane mineral scaling propensity for site-specific feed water in order to determine feasible operating conditions and appropriate levels of pretreatment necessary for the M3 pilot scale RO desalination system. Subsequently, M3 pilot system desalination studies are conducted to determine overall RO system recovery limits while scale formation is continuously monitored by the EXSOD system by matching the level of supersaturation (at the membrane surface) for the tail element of the M3 unit with the conditions in the EXSOD. If mineral scale formation is observed, automated scale detection software can initiate membrane cleaning protocols and then restore normal system operation after membrane cleaning is complete. These studies lay the groundwork for a new paradigm in the design of reverse osmosis desalination plants through the use of UCLA's novel pilot-scale RO desalination system. These concepts were demonstrated through an extensive brackish water desalination field studies conducted with UCLA's EXSOD/M3 pilot system in the in California's San Joaquin valley. Tests using the EXSOD system were able to rapidly identify insufficient pretreatment and determine the optimal antiscalant dosage for use in the M3 pilot RO system.