Denitrification of high nitrate concentration wastewater using alternative carbon sources

Abstract

The use of different organic carbon sources in the denitrification of wastewater containing 2500 mg nitrates/L in a SBR was studied. Three alternative sources of carbon were tested: wastewater from a sweet factory, a residue from a soft drinks factory and a residue from a dairy plant. The first two are sugar rich, whereas the third presents a high content in lactic acid. Maximum specific denitrification rates of between 42 and 48 mg NO 3 -N/g VSS·h were obtained. The effluents were nitrate free and very low COD concentrations were obtained in 4-6 hours reaction time, especially with the sugar-rich carbon sources. The values of the denitrifier net yield coefficient were higher than when using methanol (0.93-1.75 g VSS formed /g NOx-N reduced ). The lowest value was obtained using the lactic acid-rich residue. The optimum COD/N ratios varied between 4.6 for the lactic acid-rich carbon source and 5.5 -6.5 for the sugar-rich carbon sources.

Sorption and Release of Organics by Primary, Anaerobic, and Aerobic Activated Sludge Mixed with Raw Municipal Wastewater

“…These results are concordant with previous studies [27,29,30]. In ICL-5 nitrate removal rate declines in spite of a high COD/NO 3 ratio, which has been reported earlier to have favoured nitrate reduction [30,27]. In ICL-5 a rise in carbon concentration also lowers the phosphate/COD ratio to 0.004 in the medium which has been stated [31,32] to be a favourable condition for the metabolism of other heterotrophic organisms (OHOs) like Glycogen Accumulating Organisms (GAOs) [33][34][35].…”

Study of the dynamics and material transformation characteristics of nitrite denitrification in UASB

“…When biomass yield is not taken into consideration, the heterotrophic denitrifiers remove nitrite by the following stoichiometric equations, Equation (1) [19] and Equation (2) [20]:…”

A kinetic study on drinking water denitrification using a membrane bioreactor

“…The harmful effects of nitrates on human health are reported as methaemoglobinemia or Bluebaby syndrome [1][2][3], and nitrosamines, nitrosamides [4], which can cause the formation of carcinogens in the stomach.…”

“…Greater biomass production was observed with sucrose, when compared with ethanol and methanol. Fernández-Nava et al [4] examined the properties of sacharose-rich residue during the denitrification process. Crude syrup as a C source was used in another research performed by Lee and Welander [6].…”