Application Of Biofloc Technology Research Articles

Effect of Carbon to Nitrogen Ratio on Water Quality and Community Structure Evolution in Suspended Growth Bioreactors through Biofloc Technology

Application of biofloc technology could effectively treat wastewater. However, the effect of influent carbon to nitrogen ratio (C/N ratio) on water quality and microbial community structure evolution in suspended growth bioreactors (SGBRs) through biofloc technology is still unclear. Here, we show that the total ammonia nitrogen (TAN) and nitrite nitrogen in the effluent of the C/N 10 treatment was significantly higher than that in the C/N 15, C/N 20 and C/N 25 treatments (p < 0.05). Higher TAN removal efficiency was obtained in treatments of C/N 15, C/N 20 and C/N 25, and there was no accumulation of nitrite nitrogen and nitrate nitrogen. Increasing the C/N ratio strengthened the elimination ability of total phosphorus and chemical oxygen demand (COD). The concentrations of TAN and COD first dropped to the lowest level and then increased slightly within one cycle in all treatments. The accumulation of biomass in the reactors increased with the increasing C/N ratio, indicating that a higher C/N ratio was conducive to microbial proliferation. The 16S rRNA sequencing revealed that the microbial community diversity in SGBRs was significantly higher than that in the natural wastewater (P0). The predominant phylum were Proteobacteria, Bacteroidetes and Verrucomicrobia, but Saccharibacteria occupied a dominant position in the late period of the experiment. Pathogens, such as Aeromonas, Acidovorax, Flavobacterium, and Malikia were significantly decreased after high C/N ratio simulative wastewater treating natural wastewater in the reactors. In summary, the water quality and biomass concentrations in SGBRs can be improved under the conditions of influent C/N ratio, equal to or greater than 15.

Bio-floc technology application in olive flounder, <i>Paralichthys olivaceus</i> aquaculture according to the difference of closed recirculating systems

Bio-floc technology application in olive flounder, <i>Paralichthys olivaceus</i> aquaculture according to the difference of closed recirculating systems

Integrated aquaculture in arid environments

Around one third of the globe is classified as desert or arid (<200mm rain annually) and most such regions lack food security. Traditional freshwater aquaculture is often a marginal activity and competes with agriculture for limited water resources. Developing technologies offer new opportunities to increase productivity of aquaculture through integration with vegetable production in aquaponic systems and to reduce water requirements through the application of biofloc technology. Aquaponic systems combine aquaculture and hydroponic plant production and are integrated within a re-cycled water system. Fish waste metabolites provide the nutrients for plants grown in soil-less, hydroponic systems. Biofloc farming systems operate with minimum or zero water exchange. Suspended biofloc particles develop in fish tanks under conditions of full aeration and controlled carbon to nitrogen ratios. They comprise algae, bacteria, protozoa and particulate organic matter held in a loose matrix. They provide in-situ treatment of harmful fish metabolites, are protein rich, contain essential fatty acids, vitamins and minerals and supplement the diets of filter-feeding farmed species. The integration of fish culture with vegetable production provides new opportunities for small and medium enterprises. Integrated farms occupy a small footprint, optimise the use of resources and can be built close to population centres. This paper reviews current developments in aquaponics and biofloc technology against the background of food security needs in arid regions.

Integrated aquaculture in arid environments

Around one third of the globe is classified as desert or arid (<200mm rain annually) and most such regions lack food security. Traditional freshwater aquaculture is often a marginal activity and competes with agriculture for limited water resources. Developing technologies offer new opportunities to increase productivity of aquaculture through integration with vegetable production in aquaponic systems and to reduce water requirements through the application of biofloc technology. Aquaponic systems combine aquaculture and hydroponic plant production and are integrated within a re-cycled water system. Fish waste metabolites provide the nutrients for plants grown in soil-less, hydroponic systems. Biofloc farming systems operate with minimum or zero water exchange. Suspended biofloc particles develop in fish tanks under conditions of full aeration and controlled carbon to nitrogen ratios. They comprise algae, bacteria, protozoa and particulate organic matter held in a loose matrix. They provide in-situ treatment of harmful fish metabolites, are protein rich, contain essential fatty acids, vitamins and minerals and supplement the diets of filter-feeding farmed species. The integration of fish culture with vegetable production provides new opportunities for small and medium enterprises. Integrated farms occupy a small footprint, optimise the use of resources and can be built close to population centres. This paper reviews current developments in aquaponics and biofloc technology against the background of food security needs in arid regions.

Application of biofloc technology (BFT) in shrimp aquaculture industry

An environmental friendly technology known as Biofloc Technology (BFT) has been implemented to reduce environmental damages and to sustain production of Pacific Whiteleg shrimp, P. vannamei aquaculture industry. Since there was no intensive application of BFT being conducted in industrial scale, this study aimed to assess the impact of BFT to water quality and shrimp health. To achieve maximum growth of BFT in P. vannamei cultures, an isolated biofloc boost-up bacteria inoculum was added during each new stocking program of shrimp post-larvae (PL). Samples of water, shrimp and biofloc were collected in every ten days interval started from new stocking of shrimp PL up to harvesting periods (±100 days). Interestingly, biofloc was observed started to be formed as early as 10 days after shrimp cultivation periods, where the biofloc formation was speed up by the addition of the inoculum and thus effectively enhanced good water quality which resulted in the increasing shrimp biomass. By transferring the important knowledge of BFT to shrimp industrial scale, aggregation of microbial communities in biofloc were responsible in maintaining water quality and optimizing shrimp survival and production. Thus, knowledge on microbial composition in biofloc is deemed important for successful design and application of BFT for sustainable shrimp aquaculture industry.

Bio-floc technology application in flatfish Paralichthys olivaceus culture: Effects on water quality, growth, hematological parameters, and immune responses

Juvenile Paralichthys olivaceus (mean weight 2.69 ± 0.31 g) were raised in bio-floc and sea water for 4 months. After 4 months, individuals raised in bio-floc (mean weight 296.4 ± 31.7 g and mean length 30.5 ± 2.6 cm) and sea water (mean weight 281.2 ± 30.6 g and mean length 29.4 ± 2.3 cm) were sampled for health evaluation. Growth performance of P. olivaceus raised in bio-floc was slightly higher than that of fish reared in sea water, but the specific growth rate was not significantly different between the two groups. Hematological parameters such as hemoglobin and hematocrit were not significantly different between the two groups. Of the plasma components, glucose, aspartate aminotransferase (AST), and alanine aminotransminase (ALT) in P. olivaceus raised in bio-floc were significantly lower than those of individuals raised in sea water, whereas the other components were not significantly different between the two groups. In regards to immunity, Immunoglobulin M (Ig M) of P. olivaceus raised in bio-floc was significantly higher than those of fish raised in sea water. These results indicate that the bio-floc-rearing system was effective in improving immune function and reducing stress in P. olivaceus without significantly changing its physiology compared with fish in general sea water rearing.

Growth performance and robustness of African Catfish Clarias gariepinus (Burchell) in biofloc-based nursery production with different stocking densities

The aim of this research is to evaluate the effects of biofloc system application at different fish density on the nursery production performance and the robustness of African catfish Clarias gariepinus (Burchell) against Aeromonas hydrophila and salinity stress. An economic analysis was also performed to determine the most optimum fish density in biofloc‐based African catfish nursery production. African catfish with an average body weight of 0.96 ± 0.04 g and average body length of 4.20 ± 0.46 cm, respectively, were distributed in 12 units of circular plastic‐lined tanks (1,020 L). The experiment consisted of four treatments in triplicates, that is, a control without carbon source addition at a density of 4 fish/L, and three biofloc treatments at different densities, that is, BFT4 (4 fish/L), BFT6 (6 fish/L) and BFT8 (8 fish/L). Tapioca flour was used as the organic carbon source in biofloc systems and was added at an estimated C/N ratio of 10. Housing the fish in biofloc systems resulted in higher fish growth, more efficient feed utilization, higher fish robustness against A. hydrophila infection and salinity stress, as well as higher profitability of nursery production. Increasing the fish density resulted in higher mortality. However, higher number of fish produced and lower feed conversion ratio were observed in the treatments with higher density (6 and 8 fish/L). In conclusion, the application of biofloc technology at a density of 8 fish/L could be recommended to increase the production and profitability of African catfish nursery culture.

Culture Performance of Nile tilapia (Oreochromis niloticus) raised in a biofloc-based intensive system

In a 98‐day experiment, young of the year Nile tilapia fingerlings (5.48±1.38 g) were raised in six circular 500 L fiberglass tanks with a stocking density of 300 fish m−3. Two treatments were evaluated: (1) Culture in biofloc technology (BFT) system ; (2) Culture in pure water (control). The juveniles Nile tilapia reared in the BFT showed a substantial improvement in the growth performance (in terms of final weight, weight gain, average daily gain and specific growth rate) than the control (P0.05). The BFT system had significantly increased the total plasma protein and globulin. Whereas, the serum glucose and cortisol level of the control fish showed surprisingly increased levels compared to the biofloc group. What is more, a major difference was found within the antioxidant system in terms of, superoxide dismutase activity. The obtained results encourage the application of biofloc technology for intensive rearing of tilapia as implemented from the growth and immune response as well as the response to oxidative stress displayed by tilapia fish maintained at this system.

Biofloc technology application in aquaculture to support sustainable development goals.

SummaryBiofloc technology (BFT) application offers benefits in improving aquaculture production that could contribute to the achievement of sustainable development goals. This technology could result in higher productivity with less impact to the environment. Furthermore, biofloc systems may be developed and performed in integration with other food production, thus promoting productive integrated systems, aiming at producing more food and feed from the same area of land with fewer input. The biofloc technology is still in its infant stage. A lot more research is needed to optimise the system (in relation to operational parameters) e.g. in relation to nutrient recycling, MAMP production, immunological effects. In addition research findings will need to be communicated to farmers as the implementation of biofloc technology will require upgrading their skills.

Biofloc technology application in indoor culture of Labeo rohita (Hamilton, 1822) fingerlings: The effects on inorganic nitrogen control, growth and immunity

The present study was undertaken to investigate the effect of biofloc-based aquaculture system on inorganic nitrogen control, and growth and immunological responses of rohu (Labeo rohita). Fingerlings of rohu were cultured in indoor biofloc tanks in light-limited condition for 16 weeks with daily addition of molasses as carbon source to maintain the C/N ratio at 15. Different water quality parameters were measured at weekly interval. Growth, survival and welfare indices including stress and immunological status were measured after the end of the experimental period. Factor analysis using water quality variables indicated ammonia immobilization by heterotrophic bacteria, rather than nitrification, as the dominant mechanism influencing ammonia removal in the biofloc system. Ammonia immobilization was concomitant with microbial biomass production, as also revealed through factor analysis. The biofloc culture system enhanced the growth of rohu significantly than the control fish. As a measure of stress, the serum glucose content did not differ significantly between the fish cultured in biofloc and control system. Among the immunological parameters, respiratory burst and alkaline phosphatase activity showed significant enhancement in fish grown in biofloc system than the control. However, myeloperoxidase activity and total serum protein content did not show any statistically significant difference between biofloc and control system. The enhanced growth and welfare of the cultured fish may be attributed to in situ maintenance of water quality within the biofloc system and presence of microbial floc.

Biofloc technology application in African catfish fingerling production: The effects on the reproductive performance of broodstock and the quality of eggs and larvae

The present study evaluated the effects of biofloc technology (BFT) application on African catfish (Clarias gariepinus) fingerling production with more focus given to the reproductive performance of broodstock and the quality of eggs and larvae. For broodstock experiment, two broodstock culture systems were compared, i.e. biofloc and control systems. In biofloc systems, regular additions of organic carbon source (molasses, C/N ratio of 10) were conducted to stimulate the growth of heterotrophic microbial biomass as the main constituent of biofloc, whereas no molasses was added to the control systems. Young female broodstock with a mean body weight of 657±0g were maintained in three replicate outdoor tanks (2.5×2.0×0.8m) per treatment at a density of 5fish/m2, whereas male fish were maintained in two replicate tanks per treatment at a density of 4fish/m2. The larvae produced by the broodstocks in both systems were subsequently assessed by larval starvation tolerance test and growth test. The gonadosomatic index (GSI) and fecundity of female broodstocks in both treatments were generally comparable, except on day-122 when the relative fecundity of biofloc broodstock was 26% higher than that of the control (P<0.05). Interestingly, the embryonic development rate of eggs produced by biofloc broodstocks was higher than that of the control (P<0.05). The survival in starvation tolerance test and growth tests was notably improved in the larvae produced by biofloc broodstocks. Furthermore maintaining the larvae in biofloc systems could also enhance the fish survival and final body length. Statement of relevanceThis study demonstrates a novel research on the application of biofloc technology in broodstock and larval rearing of African catfish. Housing African catfish broodstock in biofloc systems significantly affected the embryonic development rate and the larval quality. Improvements in survival and growth were observed in the larvae housed in biofloc systems.

Organic carbon source and C/N ratio affect inorganic nitrogen profile in the biofloc-based culture media of Pacific white shrimp (Litopenaeus vannamei)

Organic carbon source and C/N ratio play an important role in aquaculture system with biofloc technology application. Nitrogen control by adding carbohydrates to the water to stimulate heterotrophic bacterial growth by converting nitrogen into bacterial biomass. The study investigated the effect molasses, tapioca, tapioca by product and rice bran as carbon sources in a biofloc media at three different C/N ratios i.e. 10, 15, and 20 on total ammonia reduction in biofloc media. Five liters of biofloc media in a conical tank was prepared for each replicate, which consisted of 500 mL of biofloc suspension collected from a shrimp culture unit with biofloc technology application and 4.5 L seawater. Pacific white shrimp culture was performed in 40L glass aquaria at a shrimp density of 30/aquarium. There was a significant interaction between carbon source and the C/N ratio applied (P&lt;0.05). The use of molasses resulted in the highest reduction rate irrespective to the C/N ratio. Keywords: molasses, tapioca, tapioca by product, rice bran, biofloc, total ammonia nitrogen

Biofloc technology positively affects Nile tilapia (Oreochromis niloticus) larvae performance

Abstract The effect of producing and culturing Nile tilapia ( Oreochromis niloticus ) larvae in biofloc technology (BFT) based systems was investigated in terms of larval growth performance and robustness. Broodstock fish were maintained in a system with and a system without the application of biofloc technology in order to produce larvae. Molasses (53% C) was added daily into the biofloc system at an estimated C/N ratio of 10. A growth test was performed with larvae that were harvested from the biofloc system and the control system and that were subsequently housed in a biofloc environment or a control environment according to a 2 × 2 factorial design. The survival of the larvae from BFT origin (90–98%) was higher than the survival of the larvae from control origin (67–75%). The growth performance of the larvae did not seem to be affected by the origin or the housing of the larvae, although the growth seemed to be more uniform when the larvae were housed in BFT water. Upon infection with the pathogenic bacterium Streptococcus agalactiae , the larvae from BFT origin showed a significantly higher survival (75–80%) than the control larvae housed in control water (ca. 55%). Housing of the control larvae in BFT water resulted in an increase in infection resistance (about 70% survival). In a salinity stress test, the tolerance of the larvae to osmotic stress at 35 g/L for 1 h was assessed. The larvae of BFT origin showed a survival of 72% and 42% at 1 h and 24 h post salinity stress, respectively. This was significantly higher than for the larvae of control origin that showed a survival of 33% and 5% at these respective time points. Overall, the data show that the application of biofloc technology for tilapia brood fish maintenance and larval production can improve Nile tilapia fry quality and production performance.

The use of biofloc technology in a South American catfish (Rhamdia quelen) hatchery: Effect of suspended solids in the performance of larvae

A 21-day experiment was conducted to evaluate the application of biofloc technology in South American catfish larvae (Rhamdia quelen) grown at a density of 25larvaeL−1. The effect of different concentrations of biofloc on the performance of larvae was also analyzed. Five treatments were tested; in three of them, catfish larvae were grown in enriched biofloc tanks arising from the intensive cultivation of tilapia (Oreochromis niloticus). In these treatments, three biofloc concentrations, expressed as total suspended solids (TSS) were tested: up to 200mgL−1 (T200), between 400 and 600mgL−1 (T400–600) and between 800 and 1000mgL−1 (T800–1000). In another treatment, called T-HET, cultivation began with clear water and the formation of biofloc and control of ammonia were performed by the daily addition of dextrose. In the control treatment, the larvae were cultured in clear water from a recirculation system. In all treatments, the larvae were fed with Artemia nauplii. The increase in TSS concentrations was not associated with the best growth of R. quelen, but the performance of the larvae was better in T200 and T-HET, compared to T400–600 and T800–1000. In T200 and T-HET, the biofloc presented a higher content of volatile suspended solids, which could be a nutritious source of food to the larvae. The lowest survival was recorded in the control treatment (10.2%) where larvae suffered from an Ichthyophthirius multifiliis infestation on the 15th day of the experiment. No infestation by I. multifiliis was observed in the biofloc treatments, where the mean survival was four times (46.9%) greater than the control. The results showed that R. quelen larvae can be grown in a biofloc system with TSS concentrations up to 1000mgL−1, but the best growth was registered in tanks with a higher percentage of volatile suspended solids (T200 and T-HET).

Immune response and disease resistance of shrimp fed biofloc grown on different carbon sources

The objective of this study was to document the immunological effects of growing shrimp in biofloc systems. The experiment consisted of four types of biofloc systems in which bioflocs were produced by daily supplementation of four different carbon sources, i.e. molasses, tapioca, tapioca-by-product, and rice bran, at an estimated C/N ratio of 15 and a control system without any organic carbon addition. Each biofloc system was stocked with Pacific white shrimp (Litopenaeus vannamei) juveniles that were reared for 49 days. The use of tapioca-by-product resulted in a higher survival (93%) of the shrimp as compared to the other carbon sources and the control. The highest yield and protein assimilation was observed when tapioca was used as the carbon source. After 49 days, phenoloxidase (PO) activity of the shrimp grown in all biofloc systems was higher than that of the shrimp from the control system. Following a challenge test by injection with infectious myonecrosis virus (IMNV), the levels of PO and respiratory burst (RB) activity in the shrimp of all biofloc treatments were higher than that of the challenged shrimp from the control treatment. An increased immunity was also suggested by the survival of the challenged shrimp from the experimental biofloc groups that was significantly higher as compared to the challenged shrimp from the control treatment, regardless of the organic carbon source used to grow the bioflocs. Overall, this study demonstrated that the application of biofloc technology may contribute to the robustness of cultured shrimp by immunostimulation and that this effect is independent of the type of carbon source used to grow the flocs.

Evaluation of Biofloc Technology Application on Water Quality and Production Performance of Red Tilapia Oreochromis sp. Cultured at Different Stocking Densities

This study evaluated the effect of biofloc technology (BFT) application on water quality and production performance of red tilapia Oreochromis sp. at different stocking densities. Three different fish densities were applied, i.e. 25, 50, and 100 fish/m 3 , and for each density there were Control (without external carbon input) and BFT treatments. Mixed sex red tilapia with an initial average body weight 77.89 + 3.71 g was cultured in 3 m 3 concrete tanks for 14 weeks. Molasses was added on BFT treatments as the organic carbon source at a C/N ratio of 15. Control treatments of each density tested showed more fluctuated water quality parameters throughout the experimental period. The highest TAN and nitrite-nitrogen were observed in control treatment at a stocking density of 100 fish/m 3 (3.97 mg TAN/L and 9.29 mg NO 2 -N/L, respectively). The highest total yield was observed in control treatment at the highest density treatment (43.50 kg), whereas the highest survival was obtained by BFT treatment at a density of 25 fish/m 3 (97.78 + 0.77%). Total feed used in BFT was lower than that of control treatments in particular at 50 fish/m 3 density (P

Biofloc technology application as a food source in a limited water exchange nursery system for pink shrimp Farfantepenaeus brasiliensis (Latreille, 1817)

In a 30-day experiment, Farfantepenaeus brasiliensis PL25 (25 ± 10 mg; 17.9 ± 1.6 mm) were raised in nine circular floating cages with a stocking density of 1000 shrimp m−3. Three treatments were evaluated: (1) culture in BFT system plus a commercial feed supply (BFT+CF); (2) culture in BFT system without feed supply (BFT) and (3) culture in clear water with feed supply (control). Post-larvae (PL) final weight (218.9, 236.5 and 176.0 mg, for BFT+CF, BFT and control respectively), final biomass (17.9, 15.7 and 8.2 g) and weight gain (193.9, 211.5 and 151.0 mg) were similar in the BFT regardless of whether they were fed a commercial diet (P>0.05), but were both significantly higher than the control (P<0.05). Survival (81.5%, 67.0% and 84.8% respectively) and final length did not differ between treatments (P>0.05). The biofloc analysis identified five main microorganism groups: protozoa (ciliate and flagellate), rotifers, cyanobacteria (filamentous and unicellular) and pennate diatoms. Free living bacteria and attached bacteria in bulk were 25.73 ± 8.63 and 0.86 ± 3.17 × 106 mL−1 respectively. Proximate analysis in the biofloc indicated high levels of crude protein (30.4%). Results confirmed favourable nutritional quality of biofloc, and enhanced growth and production of F. brasiliensis PL in biofloc systems.