G. Koch et H. Siegrist, DENITRIFICATION WITH METHANOL IN TERTIARY FILTRATION AT WASTE-WATER TREATMENT-PLANT ZURICH-WERDHOLZLI, Water science and technology, 36(1), 1997, pp. 165-172
Citations number
8
Categorie Soggetti
Water Resources","Environmental Sciences","Engineering, Civil
In co-ordination with the EU-guidelines the large wastewater treatment
plants in Switzerland have to be extended with enhanced nitrogen remo
val. Denitrification in tertiary filtration is a cost-effective altern
ative to extended denitrification in the activated sludge system, whic
h needs; additional reactor volume. At the wastewater treatment plant
Zurich-Werdholzli full-scale experiments of denitrification with metha
nol in tertiary filtration were performed during a summer and a winter
campaign of 4 months each. For this purpose one of the original 22 fi
lter cells was equipped with a methanol dosage. At temperatures of 12-
15 degrees C rates of denitrification of about 1.0 kgN m(-3) d(-1) are
attained. After main backwashing, denitrification is significantly re
duced. Frequent backwashings (several times per day) led to methanol b
reakthroughs due to biofilm loss. The yield coefficient Y-COD was 0.4
kg CODX kg(-1) CODme. In spite of methanol dosage the quality of the f
ilter effluent was very good during normal operation in the winter cam
paign. Accumulation of the nitrite intermediate product was observed i
n summer at temperatures of 20-22 degrees C. (C) 1997 IAWQ. Published
by Elsevier Science Ltd.