In this research, a novel laboratory scale anaerobic/upflow sludge
blanket filtration combined bioreactor was designed and operated to
improve the efficiency of the upflow sludge blanket filtration process
for the simultaneous removal of phosphorus and nitrogen from
wastewater. The anaerobic/upflow sludge blanket filtration technique
was developed by adding an anaerobic reactor to its influent and
operated by varying the main process parameters in order to gain the
optimum conditions. The results showed that biological removal
efficiency of nitrogen and preservation of sludge blanket strongly
depend on wastewater characteristics, hydraulic retention time, sludge
age and process controlling parameters. The combined bioreactor
performed a total nitrogen removal efficiency of 96.6 % with the sludge
age of 25 days, total hydraulic retention time of 24 h and optimum
"chemical oxygen demand/nitrogen/phosphorus" ratio of 100/5/1. This
ratio also improved the compaction quality of sludge blanket in the
upflow sludge blanket filtration clarifier. The average specific
nitrification and denitrification rates occurred during the process can
be expressed as 4.43 mg NOx-N produced/g VSS.d and 5.50 mg NOx-N
removed/g VSS.d at the optimum ratio, respectively. To avoid sludge
rising due to denitrification process, the optimum total hydraulic
retention time of 16 to 24 h was achieved based on the effluent
quality. This study suggested that the anaerobic/upflow sludge blanket
filtration bioreactor at the optimum operational conditions can be an
effective process for removal of nutrients from municipal wastewater