Pre-treatment for ultrafiltration: effect of pre-chlorination on membrane fouling
Wenzheng Yu1,2,#,Lei Xu1,Nigel Graham2,Jiuhui Qu1*
1State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
(, )
2Department of Civil and Environmental Engineering, Imperial College London, South Kensington Campus, London SW7 2AZ, UK.
()
#Now address:Department of Civil and Environmental Engineering, Imperial College London, South Kensington Campus, London SW7 2AZ, UK.
*Corresponding author: Tel: +86 10 62849128; Fax: +86 10 62849160
Supporting information
1
Other analytical methods
The UV absorbance at 254 nm, UV254, of 0.45 μm filtered solutions was determined by an ultraviolet/visible spectrophotometer (U-3010, Hitachi High Technologies Co., Japan). Dissolved organic carbon (DOC) was determined with a total organic carbon (TOC) analyzer (TOC-VCPH, Shimadzu, Japan).Residual turbidity measurements (Hach 2100, USA)were made for samples in the two membrane tanks.Activechlorine was determined by spectrophotometry using N,N-diethyl-1,4-phenylenediamine (DPD).Residual aluminium and total P after 0.45 μm membrane filtration weres measured by inductivity coupled plasma optical emission spectrometer (ICP-OES,710, Agilent Technologies, USA). The concentration of NH4+-Nwas determined by the colorimetric method using a spectrometer, and NO2--N and NO3--N were measured by Ion Chromatography (ICS-2000, Dionex, USA).
The application of hypochlorite during pretreatment of the synthetic raw water was expected to form disinfection by-products. To evaluate this,the occurrence of four trihalomethane (THM) compounds and nine haloaceticacids (HAAs) were determined following US EPA Methods 551.1 and 552.2. The compounds were extracted from samples by MTBE and then determined by GC (Agilent 6890 N, USA) equipped with a capillary column (30.0 m × 0.32 mm × 0.25 μm, HP-5, Agilent J&W, USA), and an electron capture detector (ECD).
1
Figure S1Schematic diagram of the experimental set-up(1 – raw water tank; 2 – feed peristaltic pump; 3 – high level water tank; 4 – constant level water tank; 5 – alum tank; 6 –NaClOtank; 7 – mini-peristaltic pump; 8 – mixing system; 9– flocculation system; 10 – magnetic stirrer with showing stirring speed; 11 – CUF-Cl tank; 12 – CUF tank; 13 – UF membrane module; 14 – pressure gauge; 15– suction/backwash peristaltic pump; 16 – air blower; 17– air flowmeter; 18 – air diffuser; 19 – sludge discharge)
Table S1Operational conditions of the pilot plant
Parameters / Operational conditionsNaClO (calculated as Cl) / 1 mg/L
Alum / 0.15 mM(4.05 mg/L as Al)
Mixing tank / HRT=1 min, G=184 s-1
Flocculation tanks (3 tanks) / HRT=5 min/tank, G=23 s-1
Membrane properties / nominal pore size=0.03 μm, surface area=0.025 m2
Membrane filtration / 20 L.m-2.h-1 (30 min filtration)
Membrane backwash / 40 L.m-2.h-1 (1 min backwash)
Air / 100L/h during 1 min backwash
HRT in membrane tank / 30 min
Sludge / Released every 2 days
Figure S2 SEM image of new membrane
Figure S3Occurrence andremoval of disinfection by-products in the CUF and CUF-Cl systems: a) HAAs, b) THMs
Figure S4SEM images of cake layer in CUF tank (a) and CUF-Cl tank (a)
1