Orion star a325

This study used a pilot-scale RO treatment system (Fig. S2) located in a water recycling demonstration plant in Kokura (Fukuoka, Japan) (Takabatake et al., 2013) . A brand new 4-in. spiral wound RO membrane element with the surface area of 7.43 m 2 (ESPA2-LD-4040, Hydranautics/Nitto, Oceanside, CA, USA) was installed in a pilot-scale cross-flow RO filtration system. The RO feed was the effluent from a membrane bioreactor (MBR) without disinfection (e.g. chloramination). The NH4 + , NO3 + and chemical oxygen demand of the MBR effluent during the test was determined as 0.2, 10, and 6-8 mg/L, respectively. The pilot-scale RO system was operated at a target permeate flux of 19-20 L/m 2 h. Prior to counting the bacterial cells, the RO feed underwent a 50-fold dilution using RO permeate that was subsequently filtered with MF filter (Text S2). RO feed water and permeate conductivity was manually analyzed using a conductivity meter (Orion Star™ A325, Thermo Fisher Scientific, MA, USA).

Concentrations of N-nitrosamines in RO feedwater and permeate were determined by highperformance liquid chromatography-photochemical reaction-chemiluminescence (HPLC-PR-CL) analyzers (Fujioka et al., 2016; Kodamatani et al., 2016) equipped with a six-port valve (Fig. S3) (Fujioka et al., 2017) . Sample volumes of 20 µL (RO feedwater) and 200 µL (RO permeate) were injected into the HPLC-PR-CL every 22 min. Conductivity and temperature of RO feedwater and permeate were also monitored using conductivity meters (Orion Star™ A325, Thermo Fisher Scientific, MA, USA). Concentrations of TOrCs in RO feedwater and permeate were determined using an ultra-performance liquid chromatography (UPLC)
equipped with an atmospheric pressure ionization (API) tandem mass spectrometer. The analytical system comprised of ACQUNITY UPLC system and Quattro micro API mass spectrometer (Waters, MA, USA) (Narumiya et al., 2013) .