Biofilm Properties and Simultaneous Nitrification and Denitrification in Aerobic Rotating Biological Contactors

Masuda, Sumio; Watanabe, Yoshimasa; Ishiguro, Masayoshi

doi:10.2166/wst.1991.0588

Cited by 76 publications

(23 citation statements)

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“…The obtained cell densities were in agreement with the results of Masuda et al 17 and Zhang et al 34 However, the experimental results were quite different from the model predictions. The major difference is that the models predicted more pronounced stratifications of nitrifiers and heterotrophs than the observed results.…”

Section: Spatial Microbial Distributionsupporting

confidence: 89%

“…Since the binary population biofilms were used, the experimentally observed spatial distribution of two species agreed well with the model predictions. Masuda et al 17 and Zhang et al 34 have measured microbial spatial distributions of nitrifiers in mixed-population biofilms using the microslicing technique. Although they have found the stratified spatial distribution of nitrifiers, they have not discussed interspecies competition or verified the biofilm models.…”

Section: Introductionmentioning

confidence: 99%

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Spatial microbial distributions of nitrifiers and heterotrophs in mixed-population biofilms

Okabe

Hiratia²,

Ozawa

et al. 1996

Biotechnol. Bioeng.

137

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Spatial microbial distributions of nitrifiers and heterotrophs in undefined mixed‐population biofilms were experimentally investigated using a microslicer technique and correlated with nitrification efficiency of the biofilm system. The general stratification of different bacterial groups in the biofilm was simulated using a one‐dimensional (1‐D) mathematical biofilm accumulation model (BAM) and compared with the experimental results. Biofilms were cultured at three C : N ratios of feed solutions in a partially submerged rotating biological contactor (RBC). It was shown that the biofilms were vertically stratified (from biofilm surface to substratum). At C : N = 0, heterotrophs and nitrifiers coexisted in the outermost biofilm and heterotrophs dominated in the innermost biofilm. At C : N = 1.5, heterotrophs outcompeted nitrifiers for dissolved oxygen and space; thus, heterotrophs dominated in the outermost biofilm and nitrifiers were present only in the deeper biofilm. Nitrifiers and heterotrophs coexisted in the innermost biofilm. An increase in the influent C : N ratio resulted in stronger stratification of microbial species, as well as inhibition of nitrification. In batch experiments, NH4N utilization rate (R NH 4N) was almost the same at each substrate C : N ratio even though NH4 oxidizers were predominantly present in the deeper biofilm. The biofilm performance could not be sufficiently explained by the obtained microbial spatial distribution, suggesting that one‐dimensional description of microbial distribution was not good enough and three‐dimensional measurements of microbial spatial distribution is necessary. Total bacterial densities increased by a factor of 3–17 with biofilm depth. The metabolically active cell fraction decreased from 35 ± 13% in the outermost biofilm to 15 ± 4% in the innermost biofilm, presumably due to substrate limitation. The model predicted more pronounced stratification of nitrifiers and heterotrophs than the observed results. This discrepancy could be attributed to the real biofilms that were structurally heterogeneous (e.g., water channels), which could not be described by the one‐dimensional model. The results of this study clearly indicate the limitation of 1‐D biofilm models to describe the extent of stratification of nitrifiers and heterotrophs and suggest a 3‐D model is necessary. © 1996 John Wiley & Sons, Inc.

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Section: Spatial Microbial Distributionsupporting

confidence: 89%

Section: Introductionmentioning

confidence: 99%

Spatial microbial distributions of nitrifiers and heterotrophs in mixed-population biofilms

Okabe

Hiratia²,

Ozawa

et al. 1996

Biotechnol. Bioeng.

137

View full text Add to dashboard Cite

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“…Some simultaneous nitrification and denitrification phenomena were reported [2]. The phenomena can be explained by the diffusional limitation of oxygen into the microbial floc and biofilm.…”

Section: Introductionmentioning

confidence: 99%

Improved simultaneous nitrification and denitrification in a single reactor by using two different immobilization carriers with specific oxygen transfer characteristics

Nakano

Iwasawa

Ito

et al. 2004

Bioprocess and Biosystems Engineering

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To maximize nitrogen utilization rates during nitrification and denitrification in a simultaneous reaction for direct nitrogen removal from ammonia-nitrogen in a single reactor, two different carriers were applied that immobilized nitrifiers and denitrifiers separately. With the optimized DO concentration and mixing ratio of immobilization carriers, ammonium-nitrogen was successfully removed as designed until the middle phase of treatment where nitrogen removal rate was higher than 83% of the theoretical value, although an imbalance between nitrification and denitrification occurred at a later phase of treatment where residual nitrate-nitrogen concentration was less than 2 mg/l. The new approach using two different carriers to immobilize nitrifiers and denitrifiers separately was proved useful for controlling both nitrification and denitrification rates, enabling the utilization of maximum treatment ability of both nitrifiers and denitrifiers in a single reactor for direct nitrogen removal from ammonium-nitrogen.

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“…It was also reported that, the rate of substrate consumption increased as the bio®lm thickness increased upto a limiting depth of 70±100 lm, and after that removal rate was independent of depth. Ishiguro 1978, andMasuda et al (1991), have studied the bio®lm properties in a rotating biological contactor (RBC) plant, treating the leachate from a sanitary land®ll to discover the factors in¯uencing the simultaneous nitri®cation and denitri®cation. They de®ned the bio®lm thickness as the maximum height of a bio®lm segment.…”

Section: Measurement Of Film Thicknessmentioning

confidence: 99%

A study on microbiology of biological film layer in rotating biological contactors

Venkataraman

Ramanujam

1998

Bioprocess Engineering

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Experimental studies were carried out for upgrading the secondary treated domestic sewage ef¯uent using the Rotating Biological Contactors (RBC) as an unit process in the premises of the existing water reclamation plant of Satellite Centre Building Complex of Indian Space Research Organisation at Bangalore. As part of these studies, a brief study was carried out on the microbiological aspects of the biological slime layer developed in the RBC. This study included observations on the development of the biological ®lm on wetted disc surfaces of RBC, measurement of the thickness of the biological ®lm, a discussion on signi®cance of bio®lm thickness in substrate removal, effect of wastewater characteristics on the thickness of bio®lm and determination of MLSS/MLVSS ratio of biological ®lm obtained in RBC reactor used for upgrading the secondary ef¯uent. The results of these studies are presented in this paper. The results of identi®cation of species of micro-organisms predominant in the biological slime layer in the RBC used for upgradation of secondary treated ef¯uent are discussed separately in another paper.1 Materials and methods Description of the pilot RBC plantThis pilot plant had got two RBCs of 40 cm and 20 cm diameter discs, driven by pulleys with belts connected to a single geared motor. A photograph of this pilot plant is shown in Plate 1. The diameters of pulleys were ®xed, such that the peripheral velocities of RBCs would remain same in both RBCs. The peripheral velocities for which the drive system and pulleys were catered for are 11, 13, 18 and 24 metres per minute. The RBCs had four stages with ®ve discs in each stage at 2.5 cm spacing. The con®guration of discs are shown in Fig 1. The discs were made of 2 mm thick ®bre reinforced plastic with concentric annular rings of width 2.5 cm ®xed on one side of discs. The RBC reactor vessel was fabricated out of aluminium plate 2 mm thick. The¯ow path of liquid in RBC was perpendicular to the discs. The RBC was supported on brick masonry walls at two ends and installed by the side of outlet weir of oxidation ditches of the existing wastewater recycling plant. Presettled raw sewage and presettled secondary ef¯uent from the recycling plant were fed by means of PVC pipes into the feed tank, ®tted with constant head discharge arrangements and control valves to regulate the¯ow. From the feed tanks the wastewater was connected by gravity feed pipes to the two RBCs through`V' notch plate chambers. The outlet from RBCs were lead into brick masonry chambers serving as ®nal clari®ers. These two RBCs were continuously run over 24 hours a day for over four years, and the studies were carried out.

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Biofilm Properties and Simultaneous Nitrification and Denitrification in Aerobic Rotating Biological Contactors

Cited by 76 publications

References 0 publications

Spatial microbial distributions of nitrifiers and heterotrophs in mixed-population biofilms

Spatial microbial distributions of nitrifiers and heterotrophs in mixed-population biofilms

Improved simultaneous nitrification and denitrification in a single reactor by using two different immobilization carriers with specific oxygen transfer characteristics

A study on microbiology of biological film layer in rotating biological contactors

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