Case Study

Background
Due to recent droughts in Taiwan, the government began enforcing water conservation policies to regulate water intensive
industrial end-users to reuse 70–85% of their wastewater. To comply and remain commercially viable, global optoelectronic company in Taiwan (TFT-LCD panel production) implemented a zero liquid discharge (ZLD) process to maximize water recovery. Using an advanced MBR-RO-EDR* membrane treatment system, the company has successfully recycled an average of 91% of its process water in recent years.

System Information
The wastewater influent is a mixture of waste streams collected from various stages of the panel production line. The water quality, as a result, is a complex makeup of contaminants (Table 1) and creates a challenging scenario for treatment. However, once the MBR reduces suspended solid levels, the RO and EDR ensure ultrapure water quality for reuse.

Table 1: Feed Water Makeup
Item	Feed water range
BOD	200–400 mg/L
COD	600–1,000 mg/L
Total Nitrogen (TN)	30–50 mg/L
Total Suspended Solids (TSS)	50–200 mg/L
Total Dissolved Solids (TDS)	750–1,500 mg/L
pH	2–12

LG BW 400 R G2, LG Chem’s highest rejection brackish water membrane with the new L feed spacer for reducing
differential pressure, was selected as part of the optoelectronic company’s technology procurement strategy
to deliver long-term stable production of high-quality permeate with minimal fouling, cleaning requirements, and
energy consumption. The operating conditions are listed in Table 2.

Table 2: System Information
RO feed water	MBR treated effluent
RO system	3 trains with 12:8 system array (4M)
System recovery	75–78%
System capacity	2,880 m3/d
Feed temperature	25–30 C
Feed pressure	7–9 bar

Membrane Performance
Compared to the alternative RO (non-TFN membrane) product operated at the plant, NanoH₂O™ membranes showed better and more reliable normalized permeate flow (Figure 1) and salt passage (Figure 2). Furthermore, NanoH₂O™ membranes required more than half fewer cleaning frequencies versus the non-TFN membrane, leading to notable savings in labor, chemical use, and plant downtime (Figure 1). Despite the complex ionic species composition of the wastewater, NanoH₂O™ membranes achieved high-quality permeate requirements for reuse (Table 3). LG BW 400 R G2 is a robust RO membrane element that helped lower the O&M costs of the wastewater recycling facility and realize the water conservation goals of the optoelectronic company.

Table 3: Water Quality Analysis
Item	Unit	Feed	Permeate	Rejection (%)
Al	mg/L	0.482	<0.025	>94.0
Mg	mg/L	1.75	0.082	95.3
Ca	mg/L	4.44	0.486	89.1
Na	mg/L	223	3.65	98.4
Cl	mg/L	47.6	0.27	99.4
F	mg/L	23.6	1.01	95.7
NO3	mg/L	41.1	1.36	96.7
SO4	mg/L	88.5	ND	>99.9
PO4	mg/L	415	ND	>99.9
CO3	mg CaCO3/L	<1.0	<1.0
HCO3	mg CaCO3/L	93.0	4.0	95.7
SiO2	mg/L	4.63	0.288	93.8
TOC	mg C/L	5.1	<0.5	>90.2