Removal of organic pollutants and surfactants from laundry wastewater in membrane bioreactor (MBR)

This research carried out membrane bioreactor (MBR) pilot plant tests on the treatment of industrial laundry wastewater as well as making an analysis of MBR pilot plant operational conditions. The experiments were carried out in-place at the large-scale industrial laundry in Poland with usage of real wastewater. The MBR pilot plant used worked under aerobic conditions. The laundry wastewater, containing mainly surfactants and impurities originating from washed fabrics, was supplemented with a solution of urea to increase nitrogen content and a solution of acid to adjust pH. Daily flow of raw wastewater was equal to 0.25-0.5 m(3)/d and hourly flow was equal to 13-25 L/h. The removal efficiency of organic pollutants, determined as 5-d biochemical oxygen demand and chemical oxygen demand, amounted to 95%-98% and 89%-94%, respectively; whereas in the case of other parameters, it was 32%-84% for total N, 55%-71% for total P, 94.5%-99.5% for anionic surfactants, and 98.8%-99.4% for nonionic surfactants. The quality of the purified wastewater meets the legal requirements regarding the standards for wastewater discharged to the environment. However, due to the hydraulic instability and short failure-free periods of membrane operation, the investigated system needs further optimization to be used for industrial laundry wastewater treatment plant.