REMOVING NITRATE WITH A METHYLOTROPHIC FLUIDIZED-BED - TECHNOLOGY ANDOPERATING PERFORMANCE

A pilot biological fluidized-bed plant with a capacity of 40 m3/h has been in operation since January 1988 at De Blankaart drinking water pr oduction center for removing nitrate from surface water. Methanol is u sed as the reductant. With a nitrate removal efficiency of 9.0 kg NO3- /m3 reactor.day at 3.5-degrees-C, the system has shown superior perfor mance compared with conventional fixed-bed biofilm reactors. With an i nfluent concentration of 75 mg NO3-/L, complete nitrate removal was ac hieved at an empty bed contact time of 15 min. Nitrite was not detecte d in the effluent, provided there was a slight excess of methanol (1-2 mg/L). Residual methanol was easily removed by the existing downstrea m drinking water treatment processes.