Digital textile printing (DTP) wastewater treatment using ozone and membrane filtration

Digital textile printing (DTP) is considered as an environmentally benign process because its wastewater production is relatively small compared with the conventional textile printing system. DTP is usually practiced at building office in an urban area rather than in a textile industrial complex, so that process development for on-site treatment of the DTP wastewater is currently needed. The aim of this study was to propose a DTP wastewater treatment system suitable for operation in building and to verify if the proposed system has a rationale. treatment A system should be compact and reliable because it should be installed near the DTP system. Thus, a hybrid system consisting of ozone, ultrafiltration (UF) and reverse osmosis (RO) was proposed for treatment of DTPwastewater. Prior to UF and RO, ozone was introduced to the DTP wastewater to reduce or anic loadings to membrane filtration g as well as to treat the concentrates recycled from UF and RO. When ozone was injected withC·T value of 255g·s/L, the removal efficiency of COD and color was 63 and 81%, respectively. Ozonation of the DTP wastewater led to aggregation of colloidal particles, so that the cake resistance Rc) calculated after ozone and UFwas lower than that ( of the control (= without ozonation), suggesting that pre-ozonation is beneficial to not only flux enhancement but also to good permeate water quality . Further treatment of UF permeates using RO was carried out since the UF permeates was not enough for direct dischar e or reuse. Final ef g fluents through the whole process of ozonation, UF and RO met the criteria of direct dischar e and reuse, suggesting that the proposed hybrid system could be used for g DTP wastewater treatment satisfactorily.