Biological Denitrification

Leachate from Jatibarang Landfill contains high amount of nitrogen, so it needs serious attention because it can pollute the environment. Denitrification is supposed to naturally reduce nitrogen in leachate. This study aims to determine leachate denitrifying activities in nitrogen reduction. Denitrifying communities in leachate that were collected in May 2006 from upstream and downstream were isolated and their denitrification activities were then tested in natural and synthetic media.
The nitrate reduction by denitrifier S0 culture (upstream) was higher than denitrifier S8 culture (downstream). The nitrate reduction by denitrifier S0 culture in synthetic medium during 168 hours incubation time reached 1547,9 mg/L, while in denitrifier S8 culture was only 1327,2 mg/L. The nitrate reduction by denitrifier S0 culture in natural medium pH 8,5 was higher than that of pH 7. In pH 8,5 the nitrate reduction in 168 hours reached 118,7 mg/L, while in pH 7 was only 62,2 mg/L.
From upstream and downstream leachate each obtained five isolates exhibiting different colony characteristics, they were Milk White (JDPS), Fluor White (JDPF), Grey White (JDPA), Orange (JDO), and Yellow (JDK). Those isolates were able to reduce nitrate to nitrite with different capabilities. JDPS isolate had higher capability compared to other isolates. The denitrification capabilities from the isolates in natural medium were higher than in synthetic medium. In natural medium the denitrification activities occured after the 24th hours, while in synthetic medium the denitrification activities occured after the 144th hours. This fact showed that denitrifier adaptation in natural medium was faster compared to that in synthetic medium. Furthermore, in natural medium the accumulation of nitrite had not occured.
From this study it can be concluded that leachate denitrifiers from Jatibarang Landfill have high potential denitrification activities, while its denitrification activities in leachate are low because of the low content of nitrate. Those denitrification activities are performed by denitrifying communities which contain at least 5 population mixes with variation denitrification capabilities.

Methods The experimental work was carried out in an inverse fluidized-bed biofilm reactor packed with a floating carrier as the support for biomass growth in which the continuous liquid phase (influent + recirculated effluent) was flowing downward countercurrent to the gas phase. The carrier (33% v/v) was an irregular plastic granular product with grain size in the range of 1 –3 mm and an average density of 865 kg m -3 . The bioreactor was fed continuously with increasing nitrate concentrations in a synthetic medium of tap water, potassium nitrate and sodium acetate, maintaining the C/N mass ratio at 3.5. Phosphate (-PO4 3- ) was supplied at a concentration of 3.5 mg L -1 . For each nitrate concentration the reactor was operated until steady state conditions were achieved. Nitrate, nitrite and chemical oxygen demand (COD) analyses in liquid samples were in accordance with those outlined in Standard Methods. The biofilm mass was estimated by means of dry weight (103–105 °C), total pr...

Microbial fuel cells can be designed to remove nitrogenous compounds out of wastewater, but their performance is at present limited to 0.33 kg NO 3-Nm-3 net cathode compartment (NCC) d-1. By maintaining the pH in the cathode at 7.2, nitrogen removal was increased from 0.22 to 0.50 kg NO 3-Nm-3 NCC d-1. Bio-electrochemical active microorganisms seem to struggle with the deterioration of their own environment due to slow proton fluxes. Therefore, the results suggest that an appropriate pH adjustment strategy is necessary to allow a sustained and enhanced biological activity in bio-electrochemical systems.

In recent years, the removal of nitrate as a global soil and water contaminant has been increasingly considered. Various methods have been applied to remove this inorganic pollutant from water and wastewater. Among them is an integrated " bio-electrochemical reactor" system, which is a novel method for water and wastewater denitrification. The novelty of this system is improved biological denitrification by immobilizing autohydrogenotrophic bacteria directly on the surface of a cathode, providing easy access to NO 3 - and H 2 as the electron acceptor and electron donor, respectively. The system effectiveness depends on the configuration of reactor, and the operational and environmental parameters. Identification and optimization of these parameters are important to enhance the efficiency of the system. In this review following the introduction and explanation of the process microbiology, the bio-electrochemical process is described focusing on new configurations, and the impact of important variables, namely, hydraulic retention time, electric current, pH, and carbon source. © 2012 Elsevier B.V.

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