AWWA MTC69752

This powerpoint presentation begins by presenting a brief overview of the energy intensive nature of desalination with seawater reverse osmosis (SWRO) membranes, and an effort by the Long Beach Water Department (LBWD) to identify nanofiltration (NF) membranes as a better fit for seawater desalination. The overall objectives of the prototype testing were to: verify the NF2 process side-by-side with SWRO; water quality and operational parameters (e.g. pressure, energy, fouling, etc.); optimize the NF2 process overall through system optimization of different variables, including number of elements in each vessel, mixing membrane types within each vessel. Specific objectives included: using LBWD experimental data, develop a "mechanistic" model using the pilot plant data to estimate prototype and full-scale performance, scaling-up from 4" to 8" elements; identify optimum operating conditions, flux and recovery, water quality; and, optimize NF configuration including the number of elements, and element types (combination of NF, ULPRO, BWRO, SWRO). Topics presented include: model development for first pass; model validation; scale-up from 1-element to 2- elements; scale-up from 1-element to 4-elements; scale-up from 4" single element to 8" five element configuration; and, identifying innovative configurations of NF, ULPRO, and BWRO membranes for seawater desalination. Presentation summary includes: membrane intrinsic parameters can be used to scale-up performance; optimal configuration for first pass NF is five elements per vessel; six element - energy cost is higher; four element - capital cost is prohibitive; alternative configuration could provide improvements in water quality without significant penalty on the energy consumption - ULP-ULP-NF-NF-NF. Includes tables, figures.