Ceramic Membrane Microfiltration Allows Reuse of Challenging Wastewaters at Two U.S. Locations

Though 2017 was a wet year for the southwest U.S., drought conditions resumed in 2018 and continue through today [Heim (2021)], resulting in a water shortage that is forcing industries to look for ways to reuse wastewater and rely less on fresh water sources. Two such industries have found creative ways to reuse wastewater in their processes: one by treating their own wastewater, and the other by purchasing treated effluent from a nearby wastewater plant. These solutions conserve water and reduce the industries’ expenses. One of the industries, a Houston-based oil company, is involved in hydraulic fracturing – “fracking” – which typically injects into each well 30 – 85 thousand barrels of water consisting of about 9.5% proppant (usually sand) and 0.5% other additives. Nearly half of this water returns to the surface, now containing traces of the additives as well as oil, metals, and salts from the rock formations. This “flowback” water – high in salinity, metal concentrations, and hydrocarbons – can be costly to dispose. Therefore, fracking companies are always looking for ways to reuse this water. In 2017, the oil company partnered with Aqua-Aerobic Systems (Aqua) to design, manufacture, and commission a 6,000 barrels per day (bbl/day) mobile ceramic membrane system for use at their wells in western Texas. The system operates at 6 – 8 psi TMP and removes over 98% of the hydrocarbons, iron, and suspended solids. The second industry is a southern California oil refinery that takes a portion of the effluent discharged by an adjacent 15 MGD reuse plant, which currently treats a 3:2 ratio of industrial and domestic wastewaters having a combined total dissolved solids (TDS) of up to 5,000 mg/L. The 18-year-old plant has a conventional activated sludge (CAS) process discharging to its Advanced Water Purification Facility (AWPF), which contains sand filtration, microfiltration (MF), reverse osmosis (RO), and an advanced oxidation process (AOP). The current MF system contains polymeric hollow fiber membranes, which have performed well but have had a high incidence of fiber breakage; therefore, the plant piloted the Aqua ceramic membrane system from mid-June 2018 through mid-April 2019 to determine the viability of replacing the existing system with one containing more-durable membranes. The pilot treated both tertiary and secondary effluent from the plant, with and without coagulant pretreatment. Once optimized, the pilot was able to maintain stable operation treating secondary effluent containing 4.2 mg/L Al+3 at a flux of 100 gallons per square foot of membrane area per day (gfd), over 3 times the flux of the current polymeric membranes! In addition, the pilot operated at around 97% recovery. As a result, the plant is moving forward with design and procurement of a full-scale ceramic system. This presentation describes the ceramic system used, details the performance at each site, and discusses some of the issues encountered and how they were resolved.

This presentation is available to AMTA Members only.