STUDY OF THE PERFORMANCE OF BATCH BIOLOGICAL DENITRIFICATION USING LIGNOCELLULOSIC MATERIALS AS A CARBON SOURCE IN THE TREATMENT OF LOW C/N WATER

Abstract

Nitrate pollution of groundwater and drinking water has become an increasingly serious problem across the world. In Algeria, pollution of groundwater by nitrates has become alarming. Excess nitrates in drinking water can cause childhood methemoglobinemia (blue baby syndrome) and the reduction of nitrate to nitrites in saliva can induce the formation of nitrosamines, which are known carcinogens. Among the different technologies available for nitrate removal involving ion exchange, reverse osmosis, electrodialysis, heterotrophic denitrification seem to be the most promising processes.In this process, the bacteria uses the nitrate for respiration, converting it to nitrogen gas through a series of reactions:

In the present study, in order to remove nitrates from simulated groundwater contaminated with nitrates, a natural organic substance; acorn cup powder was used as a carbon source and as a biofilm support for batch denitrification. The effect of various experimental conditions such as initial nitrate concentration, amount of carbon source and pH was studied.Batch tests were carried out in a 1L Erlenmeyer flask, 100 mL of inoculum was added to 900 mL of synthetic groundwater prepared with KNO₃, mineral salts were added. The results obtained show that the system achieved high denitrification, nitrate removal was above 98% after 24 hours of incubation when the pH was 7, NO₃^- = 70 mg/L and 8 g/L concentration powder from acorn cups. The NO₂^- level in the effluent was less than 0.07 mg/L. Nitrate removal was above 95% after 3 hours of incubation when pH was 7.1, NO₃^- = 70 mg/L and 3 g/L biomass concentration. The NO₂ level in the effluent was less than 0.0030 mg/L. Our results suggest that it is possible to use reed powder in denitrification with additional treatment for drinking water