Inland Desalination Brine Disposal: A Baseline Study from Southern California on Brine Transport Infrastructure and Treatment Potential

Abstract

In the inland region of Southern California, a 116-km brine line distribution system transports brackish desalination brine to the coast for treatment and ocean discharge; however, solid precipitation and pipeline scaling have occurred in the brine line. This case study investigated brine chemistry and solid precipitation behaviors in the brine line system. Brine chemical composition at multiple sites along the brine line was measured, and the theoretical type and amount of solid formation was predicted using chemical modeling. Lab-scale simulation experiments were performed to evaluate the impacts of antiscalant application on solid formation in the brine line. Sampling data showed that pre-existing solids discharged from inland brackish desalination plants accumulated in the brine line which may lead to scaling problems. Chemical modeling predicted that calcite, dolomite, silica, and hydroxyapatite were oversaturated but not precipitated. Lab simulation data suggested that the delayed solid formation was mostly due to the presence of antiscalants, especially secondary antiscalants in low flow turbulence conditions. Results suggests that, in order to minimize scaling issues in the brine line infrastructure, two strategies of active on-site brine pretreatment to remove antiscalants and hardness ions and operational optimization on the brine line for better flow control and real-time monitoring should be considered.