1. APHA, 1995. Standard Methods for the Examination of Water and Wastewater, 19th ed. American Public Health Association, Washington, DC
2. Active sludge and its process modification;Benfield,1980
3. Role of microorganisms in biogeochemical cycles;Bitton,1994
4. Biological fixed-film systems (a review);Brower;Wat. Env. Res.,1997
5. Nitrification at high ammonia loading rates in an activated sludge unit;Campos;Bioresource Technol.,1999