## 2 Materials and Methods  
Samples of wastewaters discharged from four optoelectronic (Plants 1-4) and six semiconductor (Plants 5-10) plants in Central Taiwan Science Park, Taiwan, were collected and analyzed in this research, and their temperature, conductivity, suspended solids (SS), chemical oxygen demand (COD), biological oxygen demand (BOD), nitrate, sulfate, ammonium, and TMAH are summarized in Table 1. Plant 1 is a LCD glass substrate (LCD-GS) manufacturing factory, Plant 2 is a photovoltaic cell (PV) and TFT-LCD manufacturing factory, Plants 3-4 are TFT-LCD manufacturing factories, Plant 5 is an integrated circuit (IC) design and manufacturing factory (including flash memory (FM) and dynamic random access memory (DRAM), Plants 6-9 are IC manufacturing factories, and Plant 10 is an IC packaging and testing factory (IC-P&T). Plant 3 is a typical TF-LCD manufacturing plant with a relatively high wastewater flow rate (12,381 CMD) and pollutant concentrations (SS 79.4 mg/L, COD 296.6 mg/L, BOD 169.43 mg/L, NH\({}_{3}\)-N 9.78 mg/L, TMAH 100.21 mg/L) among these plants. It was chosen for the subsequent real wastewater test. The experimental set-up of MnCe-GAC (granular activated carbon) processes (Figure 1) made it possible to explore ten treatment processes: GAC, MnCe-GAC, O\({}_{3}\), GAC/O\({}_{3}\), MnCe-GAC/O\({}_{3}\), H\({}_{2}\)O\({}_{2}\), GAC/H\({}_{2}\)O\({}_{2}\), MnCe-GAC/H\({}_{2}\)O\({}_{2}\), GAC/O\({}_{3}\)/H\({}_{2}\)O\({}_{2}\), and MnCe-GAC/O\({}_{3}\)/H\({}_{2}\)O\({}_{2}\). Since salts might be present in wastewaters, the effect of three model salts (including sulfate, nitrate, and carbonate) on the processes was investigated. Both synthetic (ammonium, MEA, or TMAH) and real wastewater (Plant 3) samples were treated by the above processes. A known amount of solid (1.0 g of GAC or MnCe-GAC) was packed in a column (internal diameter 1.1 cm, column height 3.9 cm, flow rate 100 mL/min). A vessel (500 mL) was filled with known concentrations of a target solution (ammonium, MEA, or TMAH) with pH adjusted to the desired values (3, 7, or 11), and the solution was circulated through the column as indicated in Figure 1. A known amount of O\({}_{3}\) and/or H\({}_{2}\)O\({}_{2}\) was added into the system as the process required. Samples were collected, filtered, and analyzed in triplicate within acceptable analytical error (\(\pm\)5%). TMAH, monomethylamine (MH, CH\({}_{6}\)ClN), dimethylamine (DH, C\({}_{2}\)H\({}_{8}\)ClN), and trimethylamine (TH, C\({}_{3}\)H\({}_{10}\)ClN) concentrations were analyzed by Dionex ICS-1100 ion chromatography system with Ion Pac CS19A IC columns and Dionex CERSTM 300. MnCe-GAC was prepared by impregnating Mn and Ce oxides onto GAC (F400, Calgon Carbon Corporation) surfaces. For example, known amounts of Mn(NO\({}_{3}\))\({}_{2}\).4H\({}_{2}\)O and Ce(NO\({}_{3}\))\({}_{3}\).6H\({}_{2}\)O solids (molar ratio of Mn:Ce = 6:4) were dissolved in deionized water. A known amount of GAC was immersed in the above solution and sonicated for 30 min before being dried in an oven at 90 \({}^{\circ}\)C for 12 h. The resulting mixture was heated at 200 \({}^{\circ}\)C for 120 min and then washed several times with deionized water to remove detachable Mn and Ce oxides. The resulting composite (MnCe-GAC) was dried at 105 \({}^{\circ}\)C and stored at room temperature until needed. Apparent bulk density, particle density, and pore volume fraction of GAC were 0.54 kg/L, 0.78 kg/L, and 0.82 kg/L, respectively. Prior to being used in this study, GAC was sieved so that the particle size was between 0.425 and 0.600 mm, washed several times with deionized water, and baked in an oven at 200 \({}^{\circ}\)C. The BET-specific surface areas and surface morphology of MnCe-GAC and GAC were examined by ASAP 2010 accelerated surface area and porosimetry system (Micromerities, Norcross, GA, USA) and field emission scanning electron microscope (FE-SEM) (SEM, ABT-150S, Topcon, Japan), respectively.