Investigation of membrane technologies for reuse of textile industry wastewater

For industries that consume excessive water such as the textile industry, the treatment and reuse of wastewater has attracted great interest in recent years and it is predicted that it will become a necessity in the future. In this context, national and international targets and standards regarding the treatment and reuse of wastewater are constantly updated for a sustainable use of water. This study investigates the treatability and reuse possibilities of textile wastewater with membrane technologies. In the study, four different treatment scenarios were applied using Ultra Filtration (UF), Nano Filtration (NF) and Reverse Osmosis (TO) membranes. In the first two scenarios, the UF/NF/TO cascade system without pretreatment was operated at both low pressure (2, 6 and 10 bar, respectively) and high pressure (5, 10 and 15 bar, respectively). In the last two scenarios, coagulation as pre-treatment and then UF/NF/TO and NF/TO systems under low pressure were studied. The flux and recovery rates, COD, TSS, Color, TDS and EC performances of the systems installed for all treatment scenarios were examined. Considering the reuse criteria of textile industry wastewater, it has been determined that the performances of high-pressure UF/NF/TO without pre-treatment, low-pressure UF/NF/TO and NF/TO with pre-treatment are sufficient. The average fluxes obtained from each membrane was determined as 41.93, 67.76 and 77.45 L/m2.h for the high pressure UF/NF/TO without pretreatment respectively; 259.29, 35.2 and 84.8 L/m2.h for pretreated UF/NF/TO respectively; and 62.48 and 92.32 L/m2.h for pre-treated NF/TO respectively. The recovery rates of these three different systems are 64%, 66% and 69% respectively. EC, TDS, TSS, COD and Color removals were found to be 88.82%, 88.94%, 100%, 97.26% and 99.82%,respectively in the UF/NF/TO system operated at high pressure. For the pre-treated UF/NF/TO and NF/TO systems, 96.17% and 96.62% for EC, 96.15% and 96.57% for TDS, 100% and 100% for TSS, 97.94% and 97.8% for COD, 99.99% and 100% for Color removal were achieved respectively. In addition, scale-up and cost analysis evaluations of the membrane systems, which were determined to be suitable for water reuse, were also carried out. As a result of the calculations, the high-pressure UF/NF/TO system without pre-treatment was suggested as the most suitable system with an initial investment cost of 11,539,831.55 € and an operation and maintenance cost of 1.66 €/m³.