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Zambrano, J., Krustok, I., Nehrenheim, E. & Carlsson, B. (2016). A simple model for algae-bacteria interaction in photo-bioreactors. Algal Research, 19(nov), 155-161
Open this publication in new window or tab >>A simple model for algae-bacteria interaction in photo-bioreactors
2016 (English)In: Algal Research, ISSN 2211-9264, Vol. 19, no nov, p. 155-161Article in journal (Refereed) Published
Abstract [en]

This work presents a simple model to describe the consortia of algae-bacteria in a photo-bioreactor. The model is inspired by the Activated Sludge Model (ASM) structure, which includes different process rates and stoichiometric parameters. The model comprises two main biomass populations (algae and bacteria), two dissolved substrates (ammonium and nitrate) and two dissolved gases (oxygen and carbon dioxide) in the reactor. The model was calibrated with data from batch experiments performed in two lab-scale photo-bioreactors. A sensitivity analysis was done to identify the parameters to be considered for the model calibration. Results indicate that the maximum algae and bacteria growth rate, bacteria growth yield and half-saturation constant for carbon were the most sensitive parameters. Moreover, the comparison between the experiments and the model shows good agreement in terms of predicting the ammonium, nitrate and oxygen concentrations in the photo-bioreactor.

Place, publisher, year, edition, pages
Elsevier, 2016
Keywords
Biomass; Photo-bioreactor; Irradiance; Modeling; Monod
National Category
Environmental Engineering
Research subject
Energy- and Environmental Engineering
Identifiers
urn:nbn:se:mdh:diva-32920 (URN)10.1016/j.algal.2016.07.022 (DOI)000390001400019 ()2-s2.0-84983467940 (Scopus ID)
Projects
More Sense
Funder
Knowledge Foundation, 20140168
Available from: 2016-08-25 Created: 2016-08-25 Last updated: 2018-07-20
Schwede, S., Anbalagan, A., Krustok, I., Lindberg, C.-F. & Nehrenheim, E. (2016). Evaluation of the microalgae-based activated sludge (MAAS) process for municipal wastewater treatment on pilot scale. In: : . Paper presented at IWA World Water Congress.
Open this publication in new window or tab >>Evaluation of the microalgae-based activated sludge (MAAS) process for municipal wastewater treatment on pilot scale
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2016 (English)Conference paper, Published paper (Refereed)
Abstract [en]

The microalgae-based activated sludge (MAAS) process was evaluated regarding the removal efficiency of organic matter and nitrogen from physiochemically pretreated municipal wastewater at different hydraulic retention time (HRT) on pilot scale. Additionally, the interplay between the algal and bacterial consortium was evaluated regarding the ability of the algal consortium to provide oxygen for bacterial oxidation processes. The results showed in general high organic matter (COD removal 75-90%) and total nitrogen (40-50%) removal at all HRTs (6, 4 and 2 days). The dissolved oxygen (DO) concentration was maintained stable at 6 days (6.04±0.47 mg L-1) and 4 days (4.24±0.62 mg L-1) HRT. However, the DO significantly declined at 2 days HRT due to loss of biomass at the high influent flow in the sedimentation unit. Nevertheless, the MAAS process functioned as a symbiotic algal-bacterial system with bacterial organic matter oxidation and nitrification and algal nutrient removal.

National Category
Water Treatment
Identifiers
urn:nbn:se:mdh:diva-34538 (URN)
Conference
IWA World Water Congress
Available from: 2016-12-22 Created: 2016-12-22 Last updated: 2017-02-02Bibliographically approved
Krustok, I., Odlare, M., Truu, J. & Nehrenheim, E. (2016). Inhibition of nitrification in municipal wastewater treating photobioreactors: effect on algal growth and nutrient uptake. Bioresource Technology, 202, 238-243
Open this publication in new window or tab >>Inhibition of nitrification in municipal wastewater treating photobioreactors: effect on algal growth and nutrient uptake
2016 (English)In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 202, p. 238-243Article in journal (Refereed) Published
Abstract [en]

The effect of inhibiting nitrification on algal growth and nutrient uptake was studied in photobioreactors treating municipal wastewater. As previous studies have indicated that algae prefer certain nitrogen species to others, and because nitrifying bacteria are inhibited by microalgae, it is important to shed more light on these interactions. In this study allylthiourea (ATU) was used to inhibit nitrification in wastewater-treating photobioreactors. The nitrification-inhibited reactors were compared to control reactors with no ATU added.

Microalgae had higher growth in the inhibited reactors, resulting in a higher chlorophyll a concentration. The species mix also differed, with Chlorella and Scenedesmus being the dominant genera in the control reactors and Cryptomonas and Chlorella dominating in the inhibited reactors. The nitrogen speciation in the reactors after 8 days incubation was also different in the two setups, with N existing mostly as NH4-N in the inhibited reactors and as NO3-N in the control reactors.

Keywords
photobioreactors, microalgae, wastewater treatment, nitrification, algal-bacterial interactions
National Category
Water Treatment
Research subject
Energy- and Environmental Engineering
Identifiers
urn:nbn:se:mdh:diva-30043 (URN)10.1016/j.biortech.2015.12.020 (DOI)000367673500032 ()26716890 (PubMedID)2-s2.0-84951304290 (Scopus ID)
Funder
Knowledge Foundation, 2011006VINNOVA, 2012-01243
Available from: 2015-12-21 Created: 2015-12-21 Last updated: 2018-10-16Bibliographically approved
Krustok, I. (2016). Microbiological analysis of municipal wastewater treating photobioreactors. (Doctoral dissertation). Västerås: Mälardalen University
Open this publication in new window or tab >>Microbiological analysis of municipal wastewater treating photobioreactors
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Microalgae reactors, commonly known as photobioreactors, have become increasingly popular as an alternative for wastewater treatment. These systems reduce pollutants and remove nutrients such as nitrogen and phosphorous compounds from wastewater utilizing microalgae and bacteria. The biomass produced in the reactors can potentially be used to produce biofuels and decrease some of the energy demands of the process.

Wastewater treating photobioreactors are a relatively new technology and many aspects of their microbiology need further study. This thesis presents a broad overview of the algal and bacterial communities present in these systems by looking at the most important species, metabolic pathways and growth dynamics of both algae and bacteria.

The experiments presented in this thesis were conducted using municipal wastewater from the Västerås wastewater treatment plant. The wastewater was inoculated with algae from Lake Mälaren and compared to non-inoculated reactors. Overall, the inoculated reactors demonstrated better algal growth than those that were not inoculated. The tested systems also removed much of the ammonium and phosphorous present in the wastewater.

The dominant algae in the tested systems belonged to the genera Scenedesmus, Desmodesmus and Chlorella. In addition to algae, the systems contained a large number of bacteria, mostly from the phyla Proteobacteria and Bacteroidetes.

The algal photobioreactors contained a lower abundance of genes related to nitrogen metabolism, virulence and antibiotic resistance compared to the initial wastewater, showing that a shift in the bacterial community had occurred. The bacteria found in the systems were shown to be involved in synthesis of vitamins essential for algae growth such as vitamin B12, suggesting cooperation between the bacteria and algae.

Abstract [sv]

I takt med att världens befolkning ökar, så produceras dagligen allt mer avfall. Detta kan orsaka stora problem för miljön. När det byggs nya system för vattenrening behöver vi även ta hänsyn till kravet att minska energiåtgången. Dagens vattenreningssystem har vissa tillkortakommanden när det gäller reningsnivåer och energianvändning. Ett alternativ till dagens system, kan vara fotobioreaktorer, dvs. vattenrening med hjälp av mikroalger. Dessa system använder mikroalger och bakterier för att rena vattnet från föroreningar, kväve och fosfor.

Vattenrening med fotobioreaktorer är en relativt ny teknik. Flera aspekter gällande biologin i dessa system har ännu inte studerats i detalj. Den här avhandlingen presenterar en översikt av de alger och bakterier som är aktiva i fotobioreaktorer. Andra viktiga aspekter som tillväxt, arter samt vattenreningsförmåga har också studerats.

Ett antal försök genomfördes där alger från Mälaren tillsattes i vatten från Västerås kommunala vattenreningsanläggning. Storleken på försöken varierade mellan 250 ml och 20 liter. Det visade sig att algerna hade en bra tillväxt samt att mängden ammonium och fosfor minskade i vattnet under försöksperioden.

De alger som tillväxte mest i studien tillhörde Scenedesmus, Desmodesmus och Chlorella. Förutom alger tillväxte även ett stort antal bakterier från grupperna Proteobacteria and Bacteroidetes. Dessa bakterier visade sig syntetisera viktiga vitaminer, t.ex. vitamin B12, som algerna normalt inte kan syntetisera själva.

Sammanfattningsvis, så presenterar denna avhandling viktig information gällande alger och bakterier i en fotobioreaktor. Informationen kan vara ett viktigt bidrag till framtida utveckling av storskaliga fotobioreaktorer för vattenrening.

Place, publisher, year, edition, pages
Västerås: Mälardalen University, 2016
Series
Mälardalen University Press Dissertations, ISSN 1651-4238 ; 196
Keywords
photobioreactors, wastewater treatment, microalgae, microbiology
National Category
Water Treatment
Research subject
Energy- and Environmental Engineering
Identifiers
urn:nbn:se:mdh:diva-30045 (URN)978-91-7485-251-6 (ISBN)
Public defence
2016-01-29, Paros, Mälardalens högskola, Västerås, 09:15 (English)
Opponent
Supervisors
Funder
Knowledge Foundation, 2011006VINNOVA, 2012-01243
Available from: 2015-12-21 Created: 2015-12-21 Last updated: 2016-01-13Bibliographically approved
Krustok, I., Diaz, J. G., Odlare, M. & Nehrenheim, E. (2015). Algae biomass cultivation in nitrogen rich biogas digestate.. Water Science and Technology, 72(10), 1723-1729
Open this publication in new window or tab >>Algae biomass cultivation in nitrogen rich biogas digestate.
2015 (English)In: Water Science and Technology, ISSN 0273-1223, E-ISSN 1996-9732, Vol. 72, no 10, p. 1723-1729Article in journal (Refereed) Published
Abstract [en]

Because microalgae are known for quick biomass growth and nutrient uptake, there has been much interest in their use in research on wastewater treatment methods. While many studies have concentrated on the algal treatment of wastewaters with low to medium ammonium concentrations, there are several liquid waste streams with high ammonium concentrations that microalgae could potentially treat. The aim of this paper was to test ammonium tolerance of the indigenous algae community of Lake Malaren and to use this mixed consortia of algae to remove nutrients from biogas digestate. Algae from Lake Malaren were cultivated in Jaworski's Medium containing a range of ammonium concentrations and the resulting algal growth was determined. The algae were able to grow at NH4-N concentrations of up to 200 mg L(-1) after which there was significant inhibition. To test the effectiveness of the lake water algae on the treatment of biogas digestate, different pre-cultivation set-ups and biogas digestate concentrations were tested. It was determined that mixing pre-cultivated suspension algae with 25% of biogas digestate by volume, resulting in an ammonium concentration of around 300 mg L(-1), produced the highest algal growth. The algae were effective in removing 72.8 ± 2.2% of NH4-N and 41.4 ± 41.4% of PO4-P.

National Category
Environmental Sciences
Identifiers
urn:nbn:se:mdh:diva-29588 (URN)10.2166/wst.2015.384 (DOI)000374290200006 ()26540532 (PubMedID)2-s2.0-84954566739 (Scopus ID)
Available from: 2015-11-19 Created: 2015-11-19 Last updated: 2017-12-01Bibliographically approved
Krustok, I., Odlare, M., M.A., S., Truu, J., Truu, M., Ligi, T. & Nehrenheim, E. (2015). Characterization of algal and microbial community growth in a wastewater treating batch photo-bioreactor inoculated with lake water. Algal Research, 11(Sept), 421-427
Open this publication in new window or tab >>Characterization of algal and microbial community growth in a wastewater treating batch photo-bioreactor inoculated with lake water
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2015 (English)In: Algal Research, ISSN 2211-9264, Vol. 11, no Sept, p. 421-427Article in journal (Refereed) Published
Abstract [en]

Microalgae grown in photo-bioreactors can be a valuable source of biomass, especially when combined with wastewater treatment. While most published research has studied pure cultures, the consortia of algae and bacteria from wastewater have more complex community dynamics which affect both the biomass production and pollutant removal. In this paper we investigate the dynamics of algal and bacterial growth in wastewater treating batch photo-bioreactors. The photo-bioreactors were inoculated with water from a nearby lake. Lake water was obtained in August, November and December in order to add native algal species and study the effects of the season. The photo-bioreactors inoculated with lake water obtained in August and November produced more biomass and grew faster than those that only contained the algae from wastewater. The results indicated a rapid decline in bacterial abundance before algae began to multiply in reactors supplemented with lake water in November and December. The reactors were also successful in removing nitrogen and phosphorous from wastewater.

Place, publisher, year, edition, pages
Elsevier, 2015
Keywords
Algal cultivation; Biomass production; Community analysis; Photo-bioreactors; Wastewater treatment
National Category
Water Treatment
Research subject
Energy- and Environmental Engineering
Identifiers
urn:nbn:se:mdh:diva-27699 (URN)10.1016/j.algal.2015.02.005 (DOI)000363046900051 ()2-s2.0-84943663075 (Scopus ID)
Funder
Knowledge Foundation, 2011006VINNOVA, 2012-01243
Note

Additional funding from SVU (12-123), Purac and Mälarenergi, and by grant IUT2-16 of the Ministry of Education and Research of the Republic of Estonia (J. Truu, M. Truu, T. Ligi).

Available from: 2015-03-16 Created: 2015-03-16 Last updated: 2017-01-03Bibliographically approved
Krustok, I. (2015). Communities of microalgae and bacteria in photobioreactors treating municipal wastewater. (Licentiate dissertation). Västerås: Mälardalens högskola
Open this publication in new window or tab >>Communities of microalgae and bacteria in photobioreactors treating municipal wastewater
2015 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Everyone who uses water produces wastewater. This inevitability creates several problems that increase with the growth of the population and industry. What to do with the wastewater, how to purify it and how to design the infrastructure are all important questions that each municipality has to deal with, taking into account ever growing demands to reduce environmental impact. In these conditions scientists and engineers have turned to biological processes to help treat the water. Currently the most commonly used wastewater treatment method known as the activated sludge process involves bacteria that help break down the pollutants. While it has been used successfully for around 100 years now, it has many limitations when faced with modern demands. As an alternative, microalgae reactors, commonly known as photobioreactors, have been suggested.

Microalgae are microscopic water organisms that can use photosynthesis to form sugars from CO2 and water. To do this they require energy from light, hence the photo part of the photobioreactor. In addition to taking up CO2 from their environment, they take up nutrients such as nitrogen and phosphorous compounds. This is a reason why microalgae have great potential for use in wastewater treatment. When grown in wastewater together with the microorganisms already present, they are able to reduce the amount of pollutants by taking them up into their cells, effectively purifying the water.

Since wastewater has its own microbial community, the biological processes taking place in a wastewater treating photobioreactor are more complex compared to growing a single species of algae in a sterile medium. With the work presented in this licentiate, we characterized the algae and bacterial communities present in photobioreactors treating wastewater in addition to finding the most optimal ways to grow algae originating from a local lake in a wastewater medium. We looked at the species found, most important metabolic pathways, growth dynamics for both algae and bacteria and water purification dynamics.

Overall, we were successful in inoculating municipal wastewater from Västerås wastewater treatment plant with algae from Lake Mälaren. The dominant algae growing in our systems belonged to the genera Scenedesmus, Desmodesmus and Chlorella. We also saw that the bacterial community was involved in synthesis of vitamins essential for algae growth. The information presented in this thesis is another step towards a better design of control and monitoring systems in full-scale photobioreactor plants.

Place, publisher, year, edition, pages
Västerås: Mälardalens högskola, 2015
Series
Mälardalen University Press Licentiate Theses, ISSN 1651-9256 ; 193
National Category
Water Treatment
Research subject
Energy- and Environmental Engineering
Identifiers
urn:nbn:se:mdh:diva-27696 (URN)978-91-7485-192-2 (ISBN)
Presentation
2015-04-17, Lambda, Mälardalens högskola, Västerås, 10:00 (English)
Opponent
Supervisors
Funder
Knowledge Foundation, 2011006VINNOVA, 2012-01243
Note

Additional funding was from SVU (12-123), Puracand Mälarenergi, and by grant IUT2-16 of the Ministry of Educationand Research of the Republic of Estonia (J. Truu, M. Truu, T. Ligi).

Available from: 2015-03-17 Created: 2015-03-16 Last updated: 2015-06-11Bibliographically approved
Krustok, I., Odlare, M., Truu, M., Truu, J., Ligi, T., Tiirik, K. & Nehrenheim, E. (2015). Effect of lake water on algal biomass and microbial community structure in municipal wastewater based lab-scale photobioreactors. Applied Microbiology and Biotechnology, 99(21), 6537-6549
Open this publication in new window or tab >>Effect of lake water on algal biomass and microbial community structure in municipal wastewater based lab-scale photobioreactors
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2015 (English)In: Applied Microbiology and Biotechnology, ISSN 0175-7598, E-ISSN 1432-0614, Vol. 99, no 21, p. 6537-6549Article in journal (Refereed) Published
Abstract [en]

Photobioreactors are a novel environmental technology that can produce biofuels with the simultaneous removal of nutrients and pollutants from wastewaters. The aim of this study was to evaluate the effect of the lake water addition to the production of algal biomass, and phylogenetic and functional structure of the algal and bacterial communities in the lab-scale bioreactors treating municipal wastewater.

The lake water addition has significant benefit to the overall algal biomass growth and nutrient reduction in the reactors with wastewater and lake water (ratio 70/30 v/v). The metagenome based survey showed that the most abundant algal phylum in these reactors was Chlorophyta with Scenedesmus being the most prominent genus. The most abundant bacterial phyla were Proteobacteria and Bacteroidetes with most dominant families being Sphingobacteriaceae, Cytophagaceae, Flavobacteriaceae, Comamonadaceae, Planctomycetaceae, Nocardiaceae and Nostocaceae. These photobioreactors were also effective in reducing the overall amount of pathogens in wastewater compared to reactors with wastewater/tap water mixture. Functional analysis of the photobioreactor metagenomes revealed an increase in relative abundance genes related to photosynthesis, synthesis of vitamins important for auxotrophic algae, and decrease in virulence and nitrogen metabolism subsystems in lake water reactors.

Keywords
biomass production; metagenome analysis; photobioreactor; wastewater treatment
National Category
Microbiology
Research subject
Biotechnology/Chemical Engineering
Identifiers
urn:nbn:se:mdh:diva-27706 (URN)10.1007/s00253-015-6580-7 (DOI)000357649200031 ()25895091 (PubMedID)2-s2.0-84937630449 (Scopus ID)
Funder
Knowledge Foundation, 2011006VINNOVA, 2012-01243
Note

Additional funding by SVU (12-123), Puracand Mälarenergi, and the Ministry of Education and Research of the Republic of Estonia (grants IUT2-16 and 3.2.0801.11-0026).

Available from: 2015-03-16 Created: 2015-03-16 Last updated: 2018-10-16Bibliographically approved
Krustok, I., Diaz, J. G. & Shabiimam, M. (2014). ALGAE BIOMASS CULTIVATION WITH AMMONIUM RICH WASTEWATERS AS SUBSTRATE: THE POTENTIAL FOR SIMULTANEOUS WASTEWATER TREATMENT AND ENERGY RECOVERY. In: : . Paper presented at 5th International Symposium on Energy from Biomass and Waste, Venice, Italy, 17-20 Nov 2014.
Open this publication in new window or tab >>ALGAE BIOMASS CULTIVATION WITH AMMONIUM RICH WASTEWATERS AS SUBSTRATE: THE POTENTIAL FOR SIMULTANEOUS WASTEWATER TREATMENT AND ENERGY RECOVERY
2014 (English)Conference paper, Published paper (Refereed)
Abstract [en]

Ammonia rich wastewaters pose risk to recipient waters and the atmosphere, and can be difficult to treat in wastewater treatment plants (WTTP) due to toxicity to the microbes in conventional biological treatment systems. This article presents an idea on how to use a combination of bacteria and microalgae for efficient treatment of wastewaters with high ammonia concentrations (200-1400 mg/L). The challenge in this research is that most algae species are sensitive to high ammonia concentrations (>1 mM)(Abalde and Mezzamo, 2009). Despite the numerous wastewaters that contain high ammonia concentrations, i.e. landfill leachate, piggery manure, reject water and biogas digestate, the progress in finding sustainable treatment methods is taking time. This despite the fact that climate change, eutrophication and eco-toxicity is negatively affected by this commonly occurring component. Further, nitrogen is a valuable nutrient that in conventional WWTP is just released into the air without any recycling or recovery.

In this article, we present a study where algae were cultivated as a mean for treatment of wastewater reject water and swine manure from a piggery farm. The algae inoculum was pretreated from lake water, sampled in mid Sweden during summer algae blooms. Lake Mälaren is a shallow lake with a rich algae consortia, optimized for the local climate. During seasonal algae blooms, the lake demonstrates the extremely rapid growth rate of the algae such as cyanobacteria, green algae and diatoms. Algae inoculum, wastewater substrate and dilution media (tap water) were mixed in various ranges of ammonium concentrations to evaluate the nutrient removal and algae biomass growth. During the algae cultivation experiment, chlorophyll, optical density and TS were used as indicators for algae biomass growth. Flow Injection System (FIA) was used for nutrient analysis.

The two main findings in this research are that algae growth is inhibited by ammonia but that it is possible to grow algae in readily high ammonia concentrations. Moreover, significant amount of ammonium were removed by algae during the cultivation in the reactors.

National Category
Environmental Sciences
Identifiers
urn:nbn:se:mdh:diva-24806 (URN)
Conference
5th International Symposium on Energy from Biomass and Waste, Venice, Italy, 17-20 Nov 2014
Projects
ACWA
Available from: 2014-04-04 Created: 2014-04-04 Last updated: 2018-01-03Bibliographically approved
Krustok, I., Nehrenheim, E., Odlare, M., M.A., S., Truu, J., Ligi, T. & Truu, M. (2014). Characterization of algal and microbial community dynamics in a wastewater photo-bioreactor using indigenous algae from lake mälaren. In: : . Paper presented at 4th International Conference on Algal Biomass Biofuels and Bioproducts.
Open this publication in new window or tab >>Characterization of algal and microbial community dynamics in a wastewater photo-bioreactor using indigenous algae from lake mälaren
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2014 (English)Conference paper, Oral presentation with published abstract (Other academic)
Abstract [en]

Microalgae grown in photo-bioreactors can be a valuable source for biomass especially when combined with the treatment of wastewater. While most published research has been studying pure cultures, consortia of algae and bacteria from the wastewater have more complex dynamics affecting both the biomass production and pollutant removal. In this paper we investigate dynamics of algal and bacterial communities in mixed culture photo-bioreactors using chlorophyll and real-time PCR analysis. Wastewater photo-bioreactors were inoculated with water from a nearby lake to add native algae species. The results indicated a decline in bacterial 16S rDNA copy numbers before algae started to multiply. The photo-bioreactors inoculated with lake algae produced more biomass and grew faster than the algae originating only from wastewater. The reactors were effective in removing ammonia from the wastewater which seemed work to mostly through nitrification thus causing an increase in nitrate concentration. There was also an increase in Cr, Co and Ni ion concentrations during the experiment suggesting they may have moved from organic complexes to the water phase as free ions.

Keywords
algae cultivation; biomass production; community analysis; photo-bioreactors; wastewater treatment
National Category
Water Treatment
Research subject
Energy- and Environmental Engineering
Identifiers
urn:nbn:se:mdh:diva-26824 (URN)
Conference
4th International Conference on Algal Biomass Biofuels and Bioproducts
Funder
Knowledge FoundationVINNOVA
Available from: 2014-12-03 Created: 2014-12-03 Last updated: 2017-03-09Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-4435-4367

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