Treatment of textile wastewater with MBBR technology for reuse purposes

As one of the largest industries worldwide, the textile industry produces high amount of wastewater in its dyeing and finishing processes. Understanding and developing effective treatment technologies for textile wastewater is environmentally important. Moving bed biofilm reactor (MBBR) technology is a relatively new method in treating textile wastewater. Due to the biofilm attached to suspended carriers, it is able to treat a larger organic load comparing to conventional biological treatment. A lab-scale MBBR pilot-plant was investigated to treat textile wastewater from a local textile industry. The pilot plant is composed of an aerobic reactor filled with 30 vol.% of the suspended biofilm carriers for biological treatment, connected to a decantation tank. The flow rate was 4 L/d and the hydraulic retention time (HRT) was 1 day. The system was operated for two months and the control of the system was taken by characterizing the water at the entrance, in the bioreactor and at the exit to determinate the working efficiency. The average removal efficiency of COD was 82%, which is similar to the COD removal efficiency in a previous study of an activated sludge treating the same textile wastewater, but with a doubled hydraulic retention time (HRT). This result showed that the MBBR system is able to achieve the same performance in treating textile wastewater as a conventional biological treatment but with twice less HRT which could also mean smaller reactor volume. Furthermore, the treated wastewater reaches high quality levels in terms of organic matter content, suspended solids and colour, which allows the reuse of the effluent for new dyeing processes. This action implies an important saving of water and dyeing auxiliaries such as salt and alkali.