Simultaneous removal of organic materials and nitrogen by micro-aerobic biofilms

Abstract

Simultaneous nitrification with denitrification was investigated using a single rotating biological contactor (RBC). The authors proposed two means to achieve simultaneous nitrification with denitrification in the single reactor: (1) to control oxygen transfer rate by reducing oxygen partial pressure (P02) in the air phase and (2) to develop a combined partially (aerobic) and fully (anaerobic) submerged RBC (CPFSR) reactor. For the former experiment, the maximum denitrification efficiency of 90 % was obtained at C:N ratio=6 and P02=0.10 atm. Moreover, heterotrophs, NH4- and NO2-oxidizers, and denitrifiers were distributed throughout the biofilm, suggesting that nitrification and denitrification can occur wheresoever the local environment meets their growth conditions. For the latter experiment, effects of type of organic matter and influent carbon:nitrogen ratio (C:N ratio) on the efficiency of simultaneous nitrification with denitrification were investigated using the CPFSR reactor. Acetate, ethylene-glycol, phenol, and poly-vinyl-alcohol (PVA) were used as carbon sources for denitrification. An excellent nitrification efficiency was obtained for all experimental runs and all organic substrates could be degraded and used for denitrification, indicating a great potential for simultaneous removals of nitrogen and xenobiotic compounds by the CPFSR reactor.

Uptake and release of inert fluorescence particles by mixed population biofilms

“…This evidence supported the previous observations that slow-growing nitrifiers and even strict anaerobes (SRB) were abundantly present in the surface of the actively growing heterotrophic biofilms (Okabe et al, 1996a,b;Watanabe et al, 1995). The nitrifiers could grow even at a low rate and make up for the loss of their population by detachment and displacement in the biofilm.…”

“…Previous studies, however, have shown that a large amount of slow growing bacteria (e.g., nitrifiers) were abundantly present in actively growing heterotrophic biofilms (Okabe et al, 1996a,b;. Furthermore, sulfate reducing bacteria (strict anaerobes) were also present in the surface of an actively growing aerobic mixed population biofilm (Watanabe et al, 1995). These experimental evidences cannot be explained by the existing biofilm accumulation models.…”

Effects of temperature on simultaneous nitrification and denitrification via nitrite in a sequencing batch biofilm reactor

“…The biofilm can also provide a long retention time for bacteria and yield less sludge. Some researchers have studied conventional biological nitrogen removal and enhanced biological phosphate removal (EBPR) in SBBR [16][17][18]. Also a few researchers have investigated SND in SBBR, mainly in DO, pH and carbon source [7,19,20].…”

Simultaneous nitrification and denitrification in step feeding biological nitrogen removal process

“…The reactor feeding consisted of synthetic wastewater with characteristics similar to those of domestic wastewater (Watnabe et al, 1995). It was prepared by using tap water, dechlorinated by the use of sodium thiosulfate, and the addition of dosages of chemicals, as indicated in Table 1.…”