Document Type : Research Paper
Chemical and Petroleum Engineering Department, Sharif University of Technology, Tehran, Iran.
Removing nitrogen, as one of the most common and abundant pollutant of ground and surface waters is
very important. For this purpose, biological nitrification and denitrification as the most economical method should be investigated. Feasibility of high load (Chemical Oxygen Demand) COD (1000-2000 mg/l) and NH4 (1000-2000 mg/l) wastewater treatment, at different Hydraulic Retention Times (HRTs) was studied in two 9-lit anaerobic-aerobic system in pre-denitrification mode. Moving Bed Biofilm Reactor (MBBR) is a new system, having all the advantages of activated sludge, fluidized bed and fixed bed processes, without disadvantages of each system, that the biofilm production takes place on the packings, moving along the height of the reactor. From the experiments carried out in this system, result, showed higher ammonia removals take place at higher ammonia and lower organic loads. Denitrification increases at higher nitrification rates because of the
increasing effect of NO3 - entering the anaerobic reactor. In spite of the fact that nitrifying bacteria are more sensitive than COD and NO3 - removing bacteria, after toxic shock by phenol as organic source,
nitrification rate increases and COD removal decreases according to the damaging effect of phenol on COD removing bacteria. Total COD removal during the study varies between 80-100%, this value changes to 30-80% for ammonia and 30-80% for ammonia and 40-90% for nitrate.