Selection of Advanced Oxidation Process for Indirect Potable Use Experience Transfer

The City of Los Angeles Department of Public Works (DPW) Bureau of Sanitation (SAN) is expanding Terminal Island Water Reclamation Plant (TIWRP) Advanced Water Purification Facility (AWPF). The AWPF Ultimate Expansion will increase the advanced water purification treatment of tertiary effluent from 15.77 m3/min (6.0 mgd) to 31.55 m3/min (12 mgd), which will be delivered to other areas of need throughout Los Angeles. The AWPF Ultimate Expansion will include an additional microfiltration (MF) and a reverse osmosis (RO) system. Advanced oxidation process (AOP) system will be implemented for the new facility and replace the existing chloroamination disinfection process. A 7,570 m3 (2.0 mg) tertiary effluent equalization tank upstream of the AWPF and a set of upgrades to the existing pumping stations and chemical addition system and utilities are also included in the project (Figure 1). The additional purified water will be distributed to Dominguez Gap Barrier, Machado Lake, Harbor Generating Station, Harbor Irrigation, and industrial users (Figure 2). The reclaimed water will replace the potable water and reduce the need for potable water imported/provided by the Los Angeles Department of Water and Power (LADWP).Candidate processes for primary disinfection and removal of organic contaminants of emerging concern (CECs) include commercially available AOPs used in the treatment of drinking water and in indirect potable reuse: peroxone (O3/H2O2), photolysis of hydrogen peroxide (UV/H2O2), and UV/NaOCl. The UV/NaOCl AOP process configuration was included due to a secondary disinfection requirement for the distribution system, with chlorine residual in the 2-3 mg/L range in the distribution. This paper focuses on the TIWRP AWPF water quality matrix, evaluation of candidate AOPs through bench- and pilot-scale testing, AOP selection, and the key process design criteria that were developed to meet the California Department of Public Health (CDPH) Groundwater Replenishment Reuse Regulations (GRRRs; CDPH, 2014).