Production of high quality water for reuse purposes: the West Basin experience

Water reuse is becoming an essential factor for developing sound water and environment managaement policies, The main challenge for the operators of water reuse facilities is to increase the cost-efficiency and reliability of water reuse systems. To achieve this objective, an R&D program has been implemented at the West Basin Recycling Plant in California to study the removal of trace organics by advanced treatment (UV disinfection, membrane filtration). The pilot studies demonstrated the efficiency of two UV systems for final disinfection and in particular its high performance for the MF/RO effluent at low UV doses. UV appears as a cost competitive alternative to chlorination; it prevents the generation of toxic chlorinated by-products and reduces the salt content. It was demonstrated that microfiltration, as a replacement of conventional lime pretreatment for reverse osmosis, also offers numerous advantages. Despite the improved removal of trace organics, the membrane pretreatment before RO leads to a saving of 45% of life costs.