The MBR Book: Principles and Applications of Membrane

80 The MBR Book
Table 2.10 Concentration of EPS components in different MBR systems (mg/gSS unless
otherwise stated)
EPSp EPSc Other Details Reference
25–30 7–8 Humic: 12–13 R, (10) Cabassud et al. (2004)
29 36 SUVA: 2.8–3.1 L/m mg S Ahn et al. (2005)*
120 40 S, (�) Gao et al. (2004b)
31–116 6–15 TOC: 37–65 Four pilot-scale Brookes et al. (2003b)
plants, Municipal
20 14 Pilot-scale plant,
Industrial
11–46 12–40 TOC: 44–47 Three full-scale
plants, Municipal
25 9 TOC: 42 Full-scale plants,
Industrial
EPSp � EPSc � 8 Jang et al. (2005a)
30–36 33–28 (20–60) Lee et al. (2003)
73 30 S, (�) Le-Clech et al. (2003b)
60 17 R, (�) Le-Clech et al. (2003b)
TOC: 250 mg/L S, MLSS: 14 g/L Nagaoka and
Nemoto (2005)
TOC: 26–83 mg/gVSS (8–80) Cho et al. (2005b)
116–101 22–24 S, (20) Ji and Zhou (2006)
*Anaerobic UASB and aerobic MBR (Ahn et al., 2005).
S: Synthetic wastewater; R: Real wastewater; (SRT in days in parenthesis; � �infinite SRT – no wastage).
A functional relationship between specific resistance, MLVSS, TMP, permeate viscosity
and EPS has recently been obtained by dimensional analysis (Cho et al.,
2005b). EPS was found to have no effect on the specific resistance below 20 and
above 80 mgEPS/gMLVSS, but played a significant role on MBR fouling between
these two limits.
Analysis of EPS isolates is normally by UV absorbance, though more extensive
analysis has been conducted by a number of authors. In a recent study based on an
intermittently aerated MBR, the EPS fraction was found to feature three main peaks
at 100, 500 and 2000 kDa following gel chromatographic analysis. EPS larger than
1000 kDa in MW were assumed to be mainly responsible for MBR fouling (Nagaoka
and Nemoto, 2005). High performance size exclusion chromatography (HPSEC), a
technique more widely used for potable raw water analysis to analyse allochthonous
natural organic matters (NOM) (Nissinen et al., 2001), has been applied to EPS.
Analysis of EPS fractions obtained from MBRs at different locations revealed their
EPS profiles to be similar (Brookes et al., 2003a; Brookes et al., 2003b; Jefferson et al.,
2004). This would seem to corroborate previous findings from ASP sludge based on
size exclusion chromatography combined with infrared micro-spectroscopy techniques
(Gorner et al., 2003), where EPS chromatographs exhibited seven distinct
peaks. Analysis revealed 45–670 kDa MW proteins and 0.5–1 kDa MW carbohydrates
to be present. The existence of low-MW proteins associated with carbohydrates
was proposed as being pivotal in floc formation and may therefore be expected
to play a significant part in MBR membrane fouling. Reported studies of EPS