Treatment of TFT-LCD wastewater by hydrolysis acidification+ two-stage AO/MBR+ozone catalytic oxidation+BAF+air flotation process

Abstract

This paper analyzed the wastewater treatment of a thin film transistor-liquid crystal display(TFT-LCD) manufacturer. In response to the complex composition, changes in water quality, high concentration of pollutants, poor biodegradability, and high discharge requirement, the wastewater was classified into organic wastewater, acid/base wastewater, and fluorine-containing wastewater for collection and pre-treatment. After pretreatment, the three types of wastewater were mixed for further treatment. Based on the characteristics of the wastewater mixed after pretreatment, a combined process of hydrolysis acidification+two-stage AO/MBR+ozone catalytic oxidation+BAF(DN type)+air flotation+sodium hypochlorite disinfection was designed and developed. The results showed that the process was stable, the average effluent COD, BOD5, NH3-N, TP, TN, SS, F-, and total Cu during trial operation were 15, 2.1, 0.16, 0.13, 3.8, 2, 0.81, and 0.19 mg/L respectively. The effluent quality could meet the design requirements stably, with direct treatment cost of about 5.17 yuan/m3.

Keywords

• tft-lcd wastewater
• hydrolytic acidification
• two-stage ao/mbr
• ozone catalytic oxidation
• biological aerated filt
• air flotation