title: Treatment of saline municipal wastewater using hybrid growth system.
abstract: BACKGROUND
  In this study, a hybrid treatment system (Fluidized Bed positioned in a biological reactor of an Activated Sludge process) was used to treat saline domestic wastewater. The performance of the mentioned hybrid system was compared with the conventional activated sludge. A pilot study was conducted, and Chemical Oxygen Demand (COD), Electrical Conductivity (EC), Total Dissolved Solids (TDS) and pH were measured to investigate treatment efficiency. Three saline wastewater samples with salt concentrations of 0.5, 1, and 1.5 % and detention times of 2, 4 and 6 h were loaded into both rectors of hybrid system and activated sludge.
  
  
  RESULTS
  The results showed that Chemical Oxygen Demand (COD) removals at salt concentrations of 0.5, 1, 1.5 % were equal to 80, 71, 48.5 for the hybrid system and 62, 47.7, 26.5 for the activated sludge system respectively. Likewise, similar results obtained for other contamination indices indicating the superiority of the hybrid system in comparison to activated sludge system. Moreover, another advantage of the hybrid system was that the activated sludge needed sludge returning while sludge returning was not required in the hybrid system. In addition, by loading fixed rate of air into both systems, dissolved oxygen concentration in the hybrid reactor is higher than the conventional reactor.
  
  
  CONCLUSIONS
  Therefore, the hybrid system had a significantly higher efficiency than conventional reactor to treat saline domestic wastewater.
authors: Department of Water and Environmental Engineering, Abbaspour School of Engineering, ShahidBeheshti University, Tehran, Iran.
authors: N
authors: N
authors: Salmanikhas
authors: Department of Water and Environmental Engineering, Abbaspour School of Engineering, ShahidBeheshti University, Tehran, Iran.
authors: M
authors: M
authors: Tizghadam
authors: Department of Water and Environmental Engineering, Abbaspour School of Engineering, ShahidBeheshti University, Tehran, Iran.
authors: A
authors: A
authors: Rashidi Mehrabadi
keywords: Activated sludge; Hybrid growth; Saline municipal wastewater