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PubMed2001

Six years' practical experience with aerobic/anoxic deammonification in biofilm systems.

Nitrogen elimination through autotrophic micro-organisms is currently in the focus of research projects on the treatment of wastewater with high nitrogen contents, for instance to be able to develop and fix dimensioning parameters for purposeful application. In fact, several industrial plants have already shown for some years that the steady operation of nitrogen elimination without carbon demand is possible. Due to the low growth rates of the participating micro-organisms, these processes can be found in particular in biofilm systems, which also allow for the simultaneous running of the two basic processes. In the following, we will discuss on the basis of the operation results of industrial and pilot-scale plants the operation stability of the aerobic/anoxic deammonification, and explain which experiences are available in particular for conversion in biofilm systems.

Bacteria, Aerobic↗

PubMed2005

Effects of microcystins on and toxin degradation by Poterioochromonas sp.

A Chrysophyceae species, Poterioochromonas sp., was isolated from Microcystis cultures. This species can efficiently prey on Microcystis and can grow faster phagotrophically than autotrophically. The growth of Poterioochromonas sp. was stimulated in the presence of microcystin-LR and microcystin-RR (in concentrations ranging from 0.1 to 4 mg/L). The growth rate of Poterioochromonas was 4-5 times higher than the control, indicating the toxins serve as growth stimuli for this organism. A subculture of toxin-treated cells, however, showed low cellular viability, suggesting that growth enhancement by microcystins was not a normal process. The antioxidant enzymatic activity of Poterioochromonas sp. was screened for toxicology analysis. Glutathione, malondialdehyde, and superoxide dismutase (SOD) content was up-regulated within 8 h of exposure to microcystin-LR (500 microg/L). A high level of SOD activity during exposure to the toxin indicated that SOD was involved in decreasing oxidative stress caused by microcystin-LR. Simultaneously with growth, Poterioochromonas was able to degrade microcystin-LR even, at a toxin concentration of 4 mg/L. This putative degradation mechanism in Poterioochromonas is explored further and discussed in this article. Our findings may shed light on understanding the role of Poterioochromonas in the aquatic ecosystem, in particular, as a grazer of toxic cyanobacteria and a biodegrader for microcystins.

Biodegradation, Environmental↗

PubMed2026

Simultaneous removal of nitrogen, Cu2+, and bisphenol A in a hydrogel-biochar-AQDS immobilized bioreactor with added bicarbonate: Performance and metagenomic insights.

As the complexity of industrial wastewater pollution continues to increase, the simultaneous removal of nitrogen, metal contaminants, and persistent organic pollutants under low carbon conditions has become a key challenge for biological treatment systems. To address the operational instability and dependence on carbon sources observed in immobilized systems when exposed to copper (Cu2+) and bisphenol A (BPA), the Pseudoalteromonas japonicus strain LY0623 was integrated into a hydrogel-biochar-AQDS composite carrier to construct a multifunctional immobilized biofilm system. Notably, under conditions containing only NaHCO3, the R4 system achieved an NH4+-N removal rate of 89%. Under conditions where Cu2+ and BPA coexist, the R4 system achieved removal of NH4+-N (89%), NO3--N (100%), Cu2+ (85%), and BPA (88%). Sediment characterization confirmed that Cu2+ was immobilized through adsorption, complexation, and microbiologically induced carbonate precipitation (MICP). Metagenomic analysis further indicated that the Pseudomonadota phylum remained the dominant phylum, while functional pathways associated with inorganic carbon assimilation, HNAD nitrogen metabolism, endogenous carbon transformation, biomineralization, electron transfer, and aromatic compound degradation were preserved. By combining ammonia oxidation driven energy production, inorganic carbon utilization, redox mediated processes, and biomineralization, this study provides a highly promising low carbon strategy for treating industrial wastewater containing mixed pollutants.

Bisphenol A Compounds↗

PubMed1986

Transdetermination of plant cells.

Tissues derived from the leaf lamina of Nicotiana tabacum L. cv. Havana 425 plants require cytokinin for continuous proliferation in culture, whereas tissues derived from the cortex of the stem are cytokinin autotrophic. Both phenotypes persist when the two types of cells are cloned, indicating that leaf- and cortex-derived cells are determined to express different cytokinin requirements in culture. We showed that cultures derived from leaf and cortex tissues of plants regenerated from cloned leaf and cortex cells exhibit the cytokinin requirement of comparable tissues of seed-grown plants. This provides direct evidence that plant cells can undergo transdetermination and that this process has an epigenetic basis.

Cell Differentiation↗

PubMed2005

Seasonal variations of organic-carbon and nutrient transport through a tropical estuary (Tsengwen) in southwestern Taiwan.

This paper reports the fluvial fluxes and estuarine transport of organic carbon and nutrients from a tropical river (Tsengwen River), southwestern Taiwan. Riverine fluxes of organic carbon and nutrients were highly variable temporally, due primarily to temporal variations in river discharge and suspended load. The sediment yield of the drainage basin during the study period (1995-1996, 616 tonne km(-2) year(-1)) was ca. 15 times lower than that of the long-term (1960-1998) average (9379 tonne km2 year(-1)), resulting mainly from the damming effect and historically low record of river water discharge (5.02 m3 s(-1)) in 1995. The flushing time of river water in the estuary varied from 5 months in the dry season to >4.5 days in the wet season and about 1 day in the flood period. Consequently, distributions of nutrients, dissolved organic carbon (DOC) and particulate organic carbon (POC) were of highly seasonal variability in the estuary. Nutrients and POC behaved nonconservatively but DOC behaved conservatively in the estuary. DOC fluxes were generally greater than POC fluxes with the exception that POC fluxes considerably exceeded DOC fluxes during the flood period. Degradation of DOC and POC within the span of flushing time was insignificant and may contribute little amount of CO2 to the estuary during the wet season and flood period. Net estuarine fluxes of nutrients were determined by riverine fluxes and estuarine removals (or additions) of nutrients. The magnitude of estuarine removal or addition for a nutrient was also seasonally variable, and these processes must be considered for net flux estimates from the river to the sea. As a result, nonconservative fluxes of dissolved inorganic phosphorus (deltaDIP) from the estuary are -0.002, -0.09 and -0.59 mmol m(-2) day(-1), respectively, for dry season, wet season and flood period, indicating internal sinks of DIP during all seasons. Due to high turbidity and short flushing time of estuarine water, deltaDIP in the flood period may be derived largely from geochemical processes rather than biological removal, and this deltaDIP should not be included in an annual estimate of carbon budget. The internal sink of phosphorus corresponds to a net organic carbon production (photosynthesis-respiration, p-r) during dry (0.21 mmol m(-2) day(-1)) and wet (9.5 mmol m(-2) day(-1)) seasons. The magnitude of net production (p-r) is 1.5 mol m(-2) year(-1), indicating that the estuary is autotrophic in 1995. However, there is a net nitrogen loss (nitrogen fixation-denitrification < 0) in 1995, but the magnitude is small (-0.17 mol m(-2) year(-1)).

Animals↗

PubMed2004

Investigation of Cr(VI) reduction in continuous-flow activated sludge systems.

The aim of this research was to investigate hexavalent chromium, Cr(VI), reduction by activated sludge and to evaluate the use of continuous-flow activated sludge systems for the treatment of Cr(VI)-containing wastewater. Three series of experiments were conducted using two parallel lab-scale activated sludge systems. During the first experiment, one system was used as a control, while the other received Cr(VI) concentrations equal to 0.5, 1, 3 and 5mg l(-1). For all concentrations added, approximately 40% of the added Cr(VI) was removed during the activated sludge process. Determination of chromium species in the dissolved and particulate phase revealed that the removed Cr(VI) was sorbed by the activated sludge flocs mainly as trivalent chromium, Cr(III), while the residual chromium in the dissolved phase was mainly detected as Cr(VI). Activated sludge ability to reduce Cr(VI) was independent of the acclimatization of biomass to Cr(VI) and it was not affected by the toxic effect of Cr(VI) on autotrophic and heterotrophic microorganisms. During the second experiment, both systems were operated under two different hydraulic residence time (theta equal to 20 and 28h) and three different initial organic substrate concentration (COD equal to 300, 150 and 0mg l(-1)). Cr(VI) reduction was favored by an increase of theta, while it was limited by influent COD concentration. Finally, at the last experiment the effect of anoxic and anaerobic reactors on Cr(VI) reduction was investigated. It was observed that the use of an anoxic zone or an anaerobic-anoxic zone ahead of the aerobic reactor favored Cr(VI) reduction, increasing mean percentage Cr(VI) reduction to almost 80%.

Anaerobiosis↗

PubMed1981

Regulation of the synthesis of ribulose-1,5-bisphosphate carboxylase and its subunits in the flagellate Chlorogonium elongatum. I. The effect of light and acetate on the synthesis and the degradation of the enzyme.

Shifting of heterotrophically cultured cells of Chlorogonium elongatum to autotrophic culture conditions results in a more than tenfold increase in the level of the chloroplastic enzyme ribulose-1,5-bisphosphate carboxylase. This increase in enzyme amount is caused by an increased synthesis of the enzyme de novo under both growth conditions. The synthesis of the enzyme is mainly under the control of two factors. Light promotes the synthesis, while acetate, the carbon source of this organisms, has a strong inhibitory effect on this process. Since a mutant lacking chlorophyll shows a normal response to the change of culture conditions the chlorophylls can be ruled out as photoreceptors.

Acetates↗

PubMed2006

Succession of sulfur-oxidizing bacteria in the microbial community on corroding concrete in sewer systems.

Microbially induced concrete corrosion (MICC) in sewer systems has been a serious problem for a long time. A better understanding of the succession of microbial community members responsible for the production of sulfuric acid is essential for the efficient control of MICC. In this study, the succession of sulfur-oxidizing bacteria (SOB) in the bacterial community on corroding concrete in a sewer system in situ was investigated over 1 year by culture-independent 16S rRNA gene-based molecular techniques. Results revealed that at least six phylotypes of SOB species were involved in the MICC process, and the predominant SOB species shifted in the following order: Thiothrix sp., Thiobacillus plumbophilus, Thiomonas intermedia, Halothiobacillus neapolitanus, Acidiphilium acidophilum, and Acidithiobacillus thiooxidans. A. thiooxidans, a hyperacidophilic SOB, was the most dominant (accounting for 70% of EUB338-mixed probe-hybridized cells) in the heavily corroded concrete after 1 year. This succession of SOB species could be dependent on the pH of the concrete surface as well as on trophic properties (e.g., autotrophic or mixotrophic) and on the ability of the SOB to utilize different sulfur compounds (e.g., H2S, S0, and S2O3(2-)). In addition, diverse heterotrophic bacterial species (e.g., halo-tolerant, neutrophilic, and acidophilic bacteria) were associated with these SOB. The microbial succession of these microorganisms was involved in the colonization of the concrete and the production of sulfuric acid. Furthermore, the vertical distribution of microbial community members revealed that A. thiooxidans was the most dominant throughout the heavily corroded concrete (gypsum) layer and that A. thiooxidans was most abundant at the highest surface (1.5-mm) layer and decreased logarithmically with depth because of oxygen and H2S transport limitations. This suggested that the production of sulfuric acid by A. thiooxidans occurred mainly on the concrete surface and the sulfuric acid produced penetrated through the corroded concrete layer and reacted with the sound concrete below.

Acidithiobacillus thiooxidans↗

PubMed1997

The origin of life and its methodological challenge.

The problem of the origin of life is discussed from a methodological point of view as an encounter between the teleological thinking of the historian and the mechanistic thinking of the chemist; and as the Kantian task of replacing teleology by mechanism. It is shown how the Popperian situational logic of historic understanding and the Popperian principle of explanatory power of scientific theories, when jointly applied to biochemistry, lead to a methodology of biochemical retrodiction, whereby common precursor functions are constructed for disparate successor functions. This methodology is exemplified by central tenets of the theory of the chemo-autotrophic origin of life: the proposal of a surface metabolism with a two-dimensional order; the basic polarity of life with negatively charged constituents on positively charged mineral surfaces; the surface-metabolic origin of phosphorylated sugar metabolism and nucleic acids; the origin of membrane lipids and of chemi-osmosis on pyrite surfaces; and the principles of the origin of the genetic machinery. The theory presents the early evolution of life as a process that begins with chemical necessity and winds up in genetic chance.

Animals↗

PubMed2004

Arsenic hyperaccumulation in gametophytes of Pteris vittata. A new model system for analysis of arsenic hyperaccumulation.

The sporophyte of the fern Pteris vittata is known to hyperaccumulate arsenic (As) in its fronds to >1% of its dry weight. Hyperaccumulation of As by plants has been identified as a valuable trait for the development of a practical phytoremediation processes for removal of this potentially toxic trace element from the environment. However, because the sporophyte of P. vittata is a slow growing perennial plant, with a large genome and no developed genetics tools, it is not ideal for investigations into the basic mechanisms underlying As hyperaccumulation in plants. However, like other homosporous ferns, P. vittata produces and releases abundant haploid spores from the parent sporophyte plant which upon germination develop as free-living, autotrophic haploid gametophyte consisting of a small (<1 mm) single-layered sheet of cells. Its small size, rapid growth rate, ease of culture, and haploid genome make the gametophyte a potentially ideal system for the application of both forward and reverse genetics for the study of As hyperaccumulation. Here we report that gametophytes of P. vittata hyperaccumulate As in a similar manner to that previously observed in the sporophyte. Gametophytes are able to grow normally in medium containing 20 mm arsenate and accumulate >2.5% of their dry weight as As. This contrasts with gametophytes of the related nonaccumulating fern Ceratopteris richardii, which die at even low (0.1 mm) As concentrations. Interestingly, gametophytes of the related As accumulator Pityrogramma calomelanos appear to tolerate and accumulate As to intermediate levels compared to P. vittata and C. richardii. Analysis of gametophyte populations from 40 different P. vittata sporophyte plants collected at different sites in Florida also revealed the existence of natural variability in As tolerance but not accumulation. Such observations should open the door to the application of new and powerful genetic tools for the dissection of the molecular mechanisms involved in As hyperaccumulation in P. vittata using gametophytes as an easily manipulated model system.

Arsenates↗

PubMed2006

Mobilisation of arsenic from a mining soil in batch slurry experiments under bio-oxidative conditions.

Laboratory investigations were performed to estimate the potential mobility of arsenic (As) from a highly contaminated gold-mining soil under bio-oxidative aerobic conditions as a potential remediation process. The selected soil was sampled from a gold-mining site in the South of France. It contained 27700 mg kg(-1) total As, with only 0.01% present under water-soluble forms. The nature of the immobilization mechanisms was identified by using complementary physical and chemical techniques. As was found to be strongly associated to iron (oxy)hydroxide solid phase by adsorption and/or co-precipitation. Determination of iron (Fe) and As mobility as a function of pH showed that the release of As was related with the dissolution of Fe (oxy)hydroxide at very low pH values. Bioleaching experiments were conducted with the objective to enhance the mobilization of As from the source material via biological oxidation of elemental sulfur (S degree) into sulfuric acid by autotrophic exogenous or indigenous bacteria naturally located in the soil (i.e. Acidithiobacillus species). Tests conducted at 30 degrees C in shaker flasks supplemented with S degree resulted in very acidic (pH < 1) and oxidative conditions (oxidation/reduction potential (ORP) around +800 mV vs. NHE) and induced the extraction of up to 35% of As over 84 days of incubation. Under the experimental conditions of the study (batch experiments), As mobilization was strongly correlated to the dissolution of Fe solid phases. As mobilization was probably limited by the saturation of the liquid phase. Chimiolithotrophic exogenous population appeared to have a minor effect on As bioleaching. Endogenous populations were shown to rapidly develop their capacity to oxidize S degree and mobilize As from the mining soil in the form of arsenate when elemental S degree was supplemented. The use of microbial population adapted to high As concentrations reduced significantly the lag period to reach optimal pH/ORP conditions, and increased As extraction rate to a maximum of 41% within 70 days of incubation. However, As reprecipitation was subsequently observed, suggesting that the solution should be periodically replaced in order to optimize the process.

Acidithiobacillus↗

PubMed1997

Towards a proteome project of cyanobacterium Synechocystis sp. strain PCC6803: linking 130 protein spots with their respective genes.

Following the complete sequencing of the genome of the univellular cyanobacterium, Synechocystis sp. strain PCC6803 within our institute, a protein-gene linkage map of this photosynthetic microorganism was successfully constructed for 130 high abundance proteins present on two-dimensional gels. An additional six proteins were analyzed, but were probably encoded extrachromosomally. In order to demonstrate the usefulness of this protein-gene linkage map, we analyzed the changes that occur in cellular proteins after illumination of PCC6803 cells. The results indicate that this protein-gene linkage map greatly simplifies the identification process of such modulated genes. After illumination, at least three distinctive spots with reduced intensity were detected on two-dimensional gels and the corresponding genes of two of these were successfully identified as chaperonin 2 and a Tortula ruralis rehydrin-related gene. Thus, the combination of the protein-gene linkage map and two-dimensional gel electrophoresis should permit a comprehensive analyses of the proteins encoded by the genome (i.e., "proteome") of this photosynthetic autotroph. This post-genome project represents a productive way of exploiting the information obtained from the sequencing of the cyanobacterium genome.

Amino Acid Sequence↗

PubMedDate not supplied

[Role of sodium ions in the absorption of C4-dicarboxylic acids by Ectothiorhodospira shaposhnikovii].

The uptake of C4-dicarboxylic acids by the phototrophic purple bacterium Ectothiorhodospira shaposhnikovii, strain 1K, involves a common transport system obligatorily dependent on sodium ions. The values of Km for the transport of succinate, malate and fumarate are 1-10(-7), 3-10(-7) and 8-10(-7) M, respectively. The transport of C4-dicarboxylic acids in an energy-dependent process; it is inhibited by m-chlorocarbonylcyanide phenylhydrazone. It has been proved that the uptake of C4-dicarboxylic acids depends on sodium ions because the latter are required for symport. The effect of membrane potential (inside negative) on succinate uptake driven by an artificial sodium gradient was dependent on pH. At pH 7.0 the uptake was inhibited by membrane potential, but was stimulated by it at pH 9.0. The cells of E. shaposhnikovii grown under the autotrophic conditions maintain the capability to take up C4-dicarboxylic acids.

Absorption↗

PubMed2003

Quantitative steps in symbiogenesis and the evolution of homeostasis.

The merging of two independent populations of heterotrophs and autotrophs into a single population of mixotrophs has occurred frequently in evolutionary history. It is an example of a wide class of related phenomena, known as symbiogenesis. The physiological basis is almost always (reciprocal) syntrophy, where each species uses the products of the other species. Symbiogenesis can repeat itself after specialization on particular assimilatory substrates. We discuss quantitative aspects and delineate eight steps from two free-living interacting populations to a single fully integrated endosymbiotic one. The whole process of gradual interlocking of the two populations could be mimicked by incremental changes of particular parameter values. The role of products gradually changes from an ecological to a physiological one. We found conditions where the free-living, epibiotic and endobiotic populations of symbionts can co-exist, as well as conditions where the endobiotic symbionts outcompete other symbionts. Our population dynamical analyses give new insights into the evolution of cellular homeostasis. We show how structural biomass with a constant chemical composition can evolve in a chemically varying environment if the parameters for the formation of products satisfy simple constraints. No additional regulation mechanisms are required for homeostasis within the context of the dynamic energy budget (DEB) theory for the uptake and use of substrates by organisms. The DEB model appears to be dosed under endosymbiosis. This means that when each free-living partner follows DEB rules for substrate uptake and use, and they become engaged in an endosymbiotic relationship, a gradual transition to a single fully integrated system is possible that again follows DEB rules for substrate uptake and use.

Animals↗

PubMed2001

Exploitation of pollen by mycorrhizal mycelial systems with special reference to nutrient recycling in boreal forests.

Very large quantities of pollen are released annually by wind-pollinated trees, which dominate northern forest ecosystems. Since pollen is enriched in both nitrogen and phosphorus, this recurrent pulse of deposition constitutes a significant potential source of these elements in what are known to be severely nutrient-limited systems. Here, we demonstrate for the first time, to our knowledge, that an ectomycorrhizal fungus, Paxillus involutus, is able to scavenge effectively for nitrogen and phosphorus in pollen and to return a significant proportion of each nutrient to its autotrophic host, Betula pendula. More than 75 and 96%, respectively, of the nitrogen and phosphorus were removed from pollen in microcosms containing the mycorrhizal fungus, 29 and 25%, respectively, being transferred to the plants. In contrast, in microcosms without the mycorrhizal fungus only 42 and 35%, respectively, of nitrogen and phosphorus were lost from the pollen, presumably as a result of export by saprotrophs, and only 12 and 7%, respectively, were transferred to the plants. We hypothesize that this process of resource recapture, by contributing significantly to the ability of the trees to sustain the necessary annual investment in pollen production, will have a major impact upon their reproductive capabilities and hence 'fitness'.

Ecosystem↗

PubMed1998

Microbiology of a nitrite-oxidizing bioreactor.

The microbiology of the biomass from a nitrite-oxidizing sequencing batch reactor (NOSBR) fed with an inorganic salts solution and nitrite as the sole energy source that had been operating for 6 months was investigated by microscopy, by culture-dependent methods, and by molecular biological methods, and the seed sludge that was used to inoculate the NOSBR was investigated by molecular biological methods. The NOSBR sludge comprised a complex and diverse microbial community containing gram-negative and gram-positive rods, cocci, and filaments. By culture-dependent methods (i.e., micromanipulation and sample dilution and spread plate inoculation), 16 heterotrophs (6 gram positive and 10 gram negative) were identified in the NOSBR sludge (RC), but no autotrophs were isolated. 16S ribosomal DNA clone libraries of the two microbial communities revealed that the seed sludge (GC) comprised a complex microbial community dominated by Proteobacteria (29% beta subclass; 18% gamma subclass) and high G + C gram-positive bacteria (10%). Three clones (4%) were closely related to the autotrophic nitrite-oxidizer Nitrospira moscoviensis. The NOSBR sludge was overwhelmingly dominated by bacteria closely related to N. moscoviensis (89%). Two clone sequences were similar to those of the genus Nitrobacter. Near-complete insert sequences of eight RC and one GC N. moscoviensis clone were determined and phylogenetically analyzed. This is the first report of the presence of bacteria from the Nitrospira phylum in wastewater treatment systems, and it is hypothesized that these bacteria are the unknown nitrite oxidizers in these processes.

Bacteria↗

PubMed2004

Development of a biological filtration model applied for advanced treatment of sewage.

A mathematical model of biological filtration process is developed in this paper. A biological filtration process has advantages that filtration action and biological activities are combined in a single reactor with aid of filter media. Both physical and biological functions are incorporated in this developed model to simulate both mechanisms. Backwashing is expressed by the assumption that a mean captured solids concentration is input as data, and a captured solids concentration is kept at that value during each filtration run. The developed model is applied to explain the experimental performance with biological filtration reactors, in which batch cultivation of autotrophic bacteria and continuous treatment of actual sewage are carried out. Its applicability is discussed by comparing the simulated results with the experimental data. This model can favourably estimate maximum accumulation of autotrophic bacteria on the medium in batch cultivation, long-term treatment performance in continuous treatment, details of water quality profiles through the filter bed, and biomass. Required hydraulic retention time for nitrification and an appropriate recirculation ratio in a winter season are discussed with this model. This model predicts that a HRT of 1.1 h or above is required to achieve nitrification with remaining NH4(+)-N of less than 1 mgN/L and that an appropriate recirculation ratio is 2-3.

Bioreactors↗

PubMed2001

Autotrophic denitrification via a novel membrane-attached biofilm reactor.

AIMS: A laboratory-scale autotrophic membrane-attached biofilm reactor was developed to remove nitrate from drinking water. METHODS AND RESULTS: Hydrogen and carbon dioxide flowed together into the lumem side of a gas-permeable silicone tube. The gases diffused through the membrane wall to feed Alcaligenes eutrophus that formed a biofilm on the surface of the silicone tube for autotrophic denitrification. Hydrogen provided the energy source, and carbon dioxide, besides serving as the carbon source, was employed to neutralize the alkalinity from denitrification. The optimal carbon dioxide concentration in the silicone tube was between 20% and 50%. CONCLUSION: This study has demonstrated that a gas-permeable silicone tube is a convenient and efficient method to feed A. eutrophus for autotrophic denitrification. Supplying a suitable amount of carbon dioxide together with hydrogen into the silicone tube solved the problem that alkalinity formation caused during denitrification. The pH of the bioreactor was maintained at about 7 to avoid nitrite accumulation, and then the nitrogen removal rate was increased. A high specific nitrogen removal rate (1.6-5.4 g Nm(2)d(-1-1) of surface area of silicone tube) was achieved. SIGNIFICANCE AND IMPACT OF THE STUDY: In addition to combining the advantages of the hydrogenotrophic denitrification process and a membrane feeding substrate bioreactor (MFSB), this bioreactor achieved a high nitrogen removal rate and is simple to operate. It therefore is highly promising in drinking-water treatment.

Biofilms↗