The MBR Book: Principles and Applications of Membrane

244 The MBR Book
Table 5.16 TFT–LCD organic wastewater characteristics
Source Stripper Developer Rinse Average value
Solvent DMSO/MEA TMAH IPA –
pH 9–11 10–13 4–10 10–11
SS (mg/L) �10 �10 �10 �10
COD (mg/L) 800–2000 100–600 500–3700 800–2000
TKN (mg/L) 70–200 60–90 90–240 100–200
NH 3-N (mg/L) 0–15 2–15 0.1–10 2
NO x-N (mg/L) 0.1–0.4 0.0–0.3 0.1–1.3 0.2 3
(a) (b) (c) (d) (e) (f)
Figure 5.30 Schematic, Bah-Teh plant: (a) anoxic tank, (b) aerobic tank, (c) anoxic tank, (d) membrane
tank, (e) UF water tank and (f) RO
Although MBRs are often identified as an effective pretreatment for reverse osmosis,
the installation of MBR-RO is a fairly recent phenomenon within the municipal
sector. Paranjape et al. (2003) reported only two such full-scale municipal facilities in
North America – City of Colony Key (1.5 MLD) and City of Laguna, (1.9 MLD) – by
2003. The high-profile NEWater project in Singapore, in operation since May 2000,
is based on MF of secondary sewage. It is only within the last 2–3 years that an
MBR-RO system has been piloted for the duty of reclamation and reuse of treated
sewage effluent for industrial process water in Singapore (Qin et al., 2006). Pilot
demonstration MBR-RO projects for municipal wastewater reuse duty in the USA
are also comparatively recent (Lozier and Fernandez, 2001).
Over the last 5 years, a number of relatively large MBR-RO effluent treatment plants
specifically for TFT–LCD wastewater treatment have been installed in Taiwan in
response to the island’s increasing stringent regulations concerning industrial water use
and reuse. Trials were originally conducted on a 13 m 3 anoxic/aerobic tank pilot plant
(3 m 3 anoxic tank, a 10 m 3 aerobic tank) using a separate ZeeWeed ® 500a module followed
by a four-stage RO plant, and achieved 80% recovery of purified water.
The first full-scale plant, 1.27 MLD capacity, was installed at Bah-Teh, Taoyuan
County, Taiwan in December 2000, designed and installed by the Green Environmental
Technology company. The treatment system involves an anoxic–aerobic–anoxic biological
process followed by an aerobic MBR with a separate membrane tank followed
by an RO unit (Fig. 5.30). Six membrane cassettes, each fitted with eight ZW500a
modules, are used to provide a total membrane surface area of 2160 m 2 . The RO array
comprises 90 Dow Filmtec fouling-resistant membranes, providing a 1.5 MLD
capacity and recovery rate of 80%.
The replacement of the conventional clarifier with an MBR obviated the occasional
severe bulking problems associated with the former. The MLSS concentration