Reuse of textile wastewater for dyeing cotton knitted fabric with hybrid treatment: Coagulation/sand filtration/UF/NF-RO.

Abstract

The aim of this study was to investigate the usefulness of a membrane hybrid process for the treatment of real textile wastewater (TWW) and its potential reuse in the dyeing of cotton knitted fabric (DCF) process. To determine a suitable pretreatment, sand filtration, coagulation, and UF hollow fiber (UF-HF) were compared on a laboratory scale in terms of turbidity, color, and total organic carbon (TOC). Here, UF-HF provided the best removal results of 93.6%, 99.0%, and 29.0%, respectively. The second stage involves the study of UF flat sheet membranes (5, 10, 20, and 50\xa0kDa). The 5\xa0kDa membrane provided the best permeate quality according to the chemical oxygen demand (COD), turbidity, TOC, conductivity, and color by 54.5%, 83.9%, 94.2%, and 45.7-83.3%, respectively. The final step was treatment with nanofiltration (NF) and reverse osmosis (RO) and these effluents were reused for dyeing. Finally, the effluents from UF-HF/5\xa0kDa UF/RO (Scenario 1) and UF-HF/5\xa0kDa UF/NF (Scenario 2) were analyzed for turbidity, COD, TOC, biological oxygen demand, conductivity, hardness, anions and cations, and color. Both scenarios provided high removal results of 76.3-83.5%, 94.6-97.7%, 88.5-99%, 95.4-98.0%, 59.2-99.0%, 88.7-98.7%, 60.7-99.1%, and 80.0-100%, respectively. They also satisfied the DCF tests compared to the standard DCF samples. The innovative aspect of this research is as follows: 1) the complete analysis of hybrid membrane separation processes for the purpose of reuse of treated textile wastewater and 2) the proposal of a new criterion for reuse for DCF.