Floc Volume Research Articles

Growth performance, immunological, and biochemical responses of stinging catfish, (Heteropneustes fossilis) fingerlings reared in a biofloc-based production system

ABSTRACT A study was conducted to compare the high-density rearing of stinging catfish (Heteropneustes fossilis) fingerlings in both a control system and a biofloc system over 100 days. In the biofloc system, probiotics and a carbon source were added, while the control group had no additions. The biofloc system showed significantly (p < .05) higher floc volume (8.34 ± 1.33 ml L−1) and improvements in growth performance, survival rate, and biomass yield. Fingerlings reared in the biofloc system had increased digestive, oxidative enzyme activities and a lower feed conversion ratio. No changes were observed in the whole-body proximate composition between the groups. However, nonspecific immune responses, such as lysozyme and myeloperoxidase, were relatively improved, and other immune parameters like respiratory burst activity and total serum immunoglobulin were significantly increased in the biofloc system. In conclusion, biofloc-based rearing significantly enhanced the growth performance, feed utilization, and immunological conditions of stinging catfish.

Influence of various carbon and nitrogen ratios in a jaggery-based biofloc rearing system on the Asian stinging catfish Heteropneustes fossilis

Biofloc technology (BFT) is becoming popular in aquaculture. As the human population has rapidly increased, so has the demand for protein, driving the expansion of aquaculture. The increased use of aqua medicines in aquaculture has led to resistant microbes. BFT offers a promising, eco-friendly solution by promoting beneficial microbes to improve fish health and reduce chemical use, supporting the industry's long-term sustainability. BFT recycles waste without water exchange by maintaining an optimal carbon-nitrogen (C:N) ratio and adding an external carbon source, which promotes the growth of heterotrophic bacteria and other essential microbes that absorb ammonia from feed and waste, forming beneficial microbial aggregates. This study evaluated the effects of various C:N ratios in a jaggery-based BFT system on water quality, growth, feed efficiency, and the well-being of Heteropneustes fossilis. A completely randomized design with triplicates (2.33 kg/m³ in 1500 L tanks) was used to compare a control group without biofloc to three BFT treatments with C:N ratios of 8:1 (CN8), 12:1 (CN12), and 16:1 (CN16) over 180 days. Daily feeding was conducted at 5–2 % of the fish's body weight (initial weight of 5.0±0.5 g). Higher C:N ratios were linked to reduced dissolved oxygen, ammonia, and nitrite levels, alongside increased total suspended solids, floc volume, and heterotrophic bacteria counts, while the CN12 had the highest levels of beneficial microbes (Firmicutes and Actinobacteria), leading to superior fish growth, survival, and biomass compared to CN8 and CN16. The CN12 also showed better stress response, hematology, immunity, and antioxidant properties. Histologically, fish in CN12 and CN8 had healthier liver and intestines compared to CN16 and control. The results suggest that a C:N ratio of 12:1 was optimal for biofloc systems used in cultivating H. fossilis, enhancing both microbial growth and water quality.

Diverse carbon sources impact the biofloc system in brackish groundwater altering water quality, fish performance, immune status, antioxidants, plasma biochemistry, pathogenic bacterial load and organ histomorphology in Florida red tilapia

A 75-day rearing trial was completed to investigate the effectiveness of different biofloc systems (BFT) on the water quality, growth performance and health status of Florida red tilapia (FRT) grown in brackish groundwater (BGW). The trial consisted of the control and three types of BFT using different carbon sources (CS), starch (ST), rice bran (RB), and wheat bran (WB) in triplicate, expressed as BF-0, BF-ST, BF-RB, and BF-WB, respectively. Fish weighing 4.98 ± 0.01 g/fish were stocked in 250-L tanks at an initial stocking density of 25 fish. The findings demonstrated significant reductions in inorganic nitrogen by-product (NH3 and NO2) levels in all BFT groups compared to the control, with an increase in floc volume and floc nutritional value, in the BF-ST and BF-RB groups. Furthermore, fish in the BF-ST and BF-RB groups showed significant improvements in fish growth indices (final weight, weight gain, and FCR). Fish in the BFT groups showed significant improvement in kidney function indices and plasma lipids with no significant changes in liver enzyme activity compared to the control. Lower stress markers (glucose and cortisol) and higher digestive enzyme activity (lipase and protease), innate immune parameters and antioxidants were reported in fish of the BF-ST and BF-RB groups compared to the control fish. Histopathological inspection revealed that the BF-ST fish exhibited healthier livers and shared healthier intestines with BF-RB fish compared to the control group. In conclusion, RB is an appropriate CS with BGW for desert aquaculture due to its availability, inexpensiveness, and comparable outcomes with ST.

The Impact of Silica Addition on Floc Volume Density in the Biofloc System for Juvenile Red Tilapia (Oreochromis niloticus)

Biofloc technology is a solution to the problem of waste management in aquaculture. Biofloc systems are beneficial because they not only reduce inorganic nitrogen waste from feed residues and fish excrement but also produce flocs. The aim of this research is to determine the effect of silica addition on floc volume density in the biofloc system for juvenile red tilapia. The research was conducted from January to March 2024 at the Center of Excellence in Science and Technology (PUI-PT) for Functional Nano Powder at Padjadjaran University. This study uses a Completely Randomized Design (CRD) experimental method with four treatments and three replications. The treatments used were (A) control, (B) 15 ppm silica, (C) 20 ppm silica, and (D) 25 ppm silica. The study used cylindrical containers with a capacity of 19 liters filled with 15 liters of water, a stocking density of 10 juvenile red tilapia per cylinder, with the juvenile measuring 3-4 cm and weighing 3-4 g. The parameters observed were floc volume density and water quality. The data on floc volume density and water quality were analyzed descriptively. The results showed that the addition of 25 ppm silica in the biofloc system was the best treatment for floc volume density. This was evidenced by the results in treatment D (25 ppm) achieving a floc volume density of 26.5 ml/L, which falls into the dense category. Therefore, the addition of silica concentration in the biofloc system can increase floc volume density.

The use of different carbon sources to maintain water quality and growth performance of sangkuriang catfish (Clarias gariepinus) in the biofloc aquaculture system

ABSTRACT Intensive cultivation of sangkuriang catfish (Clarias gariepinus) has the potential to increase toxic inorganic compounds. Biofloc is one way to offset the negative impact of the large amount of ammonia being converted into floc by utilizing heterotrophic bacteria with the addition of a carbon source. This study analyzes the effect of carbon type on water quality and growth performance of sangkuriang catfish. Used a completely randomized design with three treatments and three replications: probiotics + molasses, probiotics + wheat flour, and probiotics + sugar. The results of the research show that wheat flour and sugar could substitute molasses carbon as seen from the results of the carbon content tested which shows high values for wheat flour (46.16%), sugar (43.65%), and molasses (23.16%). Water quality and growth performance of sangkuriang catfish were not significantly different (p > 0 .05). The addition of carbon sources had a positive effect on ammonia, nitrite, total intestinal bacteria, and floc volume (p < 0 .05).

Effects of Difference C/N Ratio on Water Quality of White Leg Shrimp (Litopenaeus vannamei) Cultivation

Biotechnology is used to apply technology to the C/N ratio by stimulating the activities of heterotrophic microorganisms, which derive food from carbon and nitrogen substrates in a certain ratio. The goal of this research was to see how the optimal carbon-nitrogen ratio affected water quality and floc volume in white leg shrimp (Litopenaeus vannamei) farming. This study took place in the UPT Integrated Laboratory Unkhair in Ternate City in July and August 2021. A fully randomized design (CRD) with four treatments and three replications was used in this investigation. Different C/N ratios had an effect on ammonia, nitrite, nitrate, floc volume, and feed conversion ratio, according to the research. The water quality parameters are still suitable for white leg shrimp cultivation. In white leg shrimp culture, the addition of C-organic molasses (different C/N ratios) was able to reduce the concentrations of (NH3), (NO2), and (NO3), and also greatly increase the flock volume and streamline the feed conversion ratio.

Mineral supplementation in biofloc influences growth and haemato-biochemical indices of Genetically Improved Farmed Tilapia reared in inland saline ground water

An experiment for a period of 60 days was performed with species specific mineral supplementation in biofloc system for GIFT tilapia reared in inland saline water. Four different concentrations of formulated mineral mixture (10, 15, 20, 25 g L−1) were supplemented in the subculture of biofloc inoculum for different treatments (T1, T2, T3, and T4). In contrast, two control groups (conventional culture system (C) and a standard biofloc control (BC) devoid of mineral supplements) were maintained. Major water quality parameters were optimal except alkalinity and pH, which were fluctuated in the treatment groups, and higher turbidity was noticed only in the T4 group. The minerals supplemented groups had lower levels of TAN, nitrite (NO2) and nitrate (NO3) than conventional biofloc system (BC). Floc parameters such as floc volume, total suspended solids (TSS), total dissolved solids (TDS) and total solids (TS) were higher than the control. Haematological parameters Hb (haemoglobin) and WBC (white blood corpuscles) of fish reared in treatments were higher, ranging from (8.2 ± 0.64 −10.47 ± 0.66 g dL−1) and (187.83–215.17 ± 6.58 per cumm) respectively (P < 0.05) compared to both the controls. Serum parameters of fish was recorded to be higher in T2. The proximate composition analysis revealed an enhanced crude protein content (33.22 ± 1.00%, 67.68 ± 0.2%) and crude lipid (5.24 ± 0.22% & 15.18 ± 0.58%) (P > 0.05) content from BC, but ash content (39.11 ± 0.1% & 20.35 ± 0.21%) from T4 in both dried biofloc and fish samples were higher than rest of the groups. Specific growth rate (SGR) and weight gain (WG) were recorded to be significantly higher in the T2 group. Feed conversion ratio (FCR) was observed to be better in all the treatments and the BC group than conventional control. The current investigation showed that subculture of biofloc inoculum supplemented with formulated mineral mix of 15 g L−1 could be effective in terms of water quality maintenance, feed utilization, growth, survival and biochemical parameters of GIFT tilapia reared in inland saline ground water.

QUANTITATIVE DETERMINATION OF THE STRENGTH OF ACTIVATED SLUDGE FLOCKS IN BIOLOGICAL TREATMENT TECHNOLOGIES

The performance of sludge and the effectiveness of wastewater treatment in various biological treatment facilities are influenced by the morphological features of activated sludge flocs. Currently, these features are assessed qualitatively through visual inspection, without statistical processing of the data. The article presents the results of quantitative determination of the strength of activated sludge flocs. A computerized method has been created to quantify the morphological characteristics of activated sludge flocs by analyzing sludge micrographs using the ImageJ software. Color and contrast indices were used to quantify the strength of the flocs. Photographs of activated sludge from the work of D. Eikelboom were used as standards for determining strength. In the calculations, we used photographs by D. Eikelboom taken at a magnification of 300 times (100 pixels) and 150 times (50 pixels). A laboratory study of the effect of Mg ions on the properties of activated sludge flocs was carried out when controlling the morphology of the flakes using the developed computerized technique. Examining the impact of Mg ions on activated sludge flocs revealed that higher magnesium concentrations in the sludge liquid result in increased linear dimensions (by 59%), floc area (by 81%) and floc volume (by 275%), but concurrently lead to a decrease in the strength of activated sludge flakes (by 21%). The obtained results in general indicated the positive effect of magnesium ion on the sedimentation properties of sludge in the aerotank-settlement system. A scale for quantitative determination of the strength of activated sludge flocs has been constructed. The developed computerized method enhances the precision and detail of visual evaluations of the technological attributes of activated sludge flocs, enabling the detection of even the smallest changes in the morphological characteristics across different wastewater treatment technologies. Keywords: activated sludge, flocs, concentration of magnesium, strength, technological characteristics.

Acidifying remediation and microbial bioremediation decrease ammoniacal nitrogen, orthophosphates, and total suspended solids levels in intensive Nile tilapia farming under biofloc conditions

In biofloc technology (BFT) systems, the formation of bioflocs and accumulation of suspended solids are constant, which can cause impairments in water quality parameters and negatively impact the growth performance of farmed animals. We herein investigated two integrated solutions for intensive farming of Nile tilapia under BFT conditions. In this study, EUROGUARD® SOFT F60 (60% formic acid and 40% lignosulfonic acid) was used as the acidifying remediator, while ADD LIFE PRO BACIL ACQUA based on a mixture of Bacillus spp. was used as the microbial bioremediator. First, assays were conducted for in vitro inhibition tests of acidifying remediator against seven different strains of pathogenic bacteria. A dose-response test was performed for both acdifying bioremediator and microbial bioremediator. Then, an in vivo assay was conducted over four weeks. In 12 BFT units with a capacity of 250 L each, one group received the acidifying remediator at a concentration of 2.5 part per million (ppm), while another group received the bioremediator Bacillus spp. at a concentration of 0.10 g m−3 directly in tank water. A control group without aditives was also established, all in quadruplicate. The culture environment was evaluated daily by measuring dissolved oxygen, temperature, floc volume and weekly by measuring total ammonia nitrogen (TAN), ammoniacal nitrogen (N−NH3), nitrite (N-NO2), nitrate (N-NO3), alkalinity (CaCO3), orthophosphate (PO43−), electrical conductivity (μS−1), potential of hydrogen (pH) and total suspended solids (TSS). At the end of the period, in the in vivo assay, the bacterial community in the BFT, hematological parameters, and zootechnical performance of the tilapia were evaluated. In in vitro inhibition tests, the acidifying remediator inhibited the growth of all pathogenic bacteria evaluated. All concentrations reduced the count of filamentous bacteria, and the pH values were dose-dependent. Both in vivo treatments altered bacterial communities. Both treatment groups had lower concentrations of N-NH3, N-NO2 and N-NO3. PO43− content was lower in the acidifying remediator group. CaCO3 was higher in the treatment groups, while TSS was higher in the control group. Both remediation strategies were efficient in removing nitrogenous chemical compounds. However, the acidifying remediator concomitantly reduced N-NH3, N-NO2− and PO43− levels, becoming a powerful ally in the reduction of aquaculture effluents, as well as in the reduction of potentially pathogenic bacteria in tilapia culture.

Effect on water quality, growth performance and economics of giant freshwater prawn, Macrobrachium rosenbergii with partial feed in biofloc system

AbstractThe aim of the present study was to evaluate the water quality, growth performance, body composition, length–weight relationship, condition factors and benefit–cost analysis of giant freshwater prawn (Macrobrachium rosenbergii) cultured with biofloc system in pond conditions. The experiment was conducted in twelve (12) experimental ponds, each measuring 240 m2. The control group was cultured without any biofloc (T1), and biofloc‐based three treatments were biofloc with 100% feed (T2), biofloc with 90% feed (T3) and biofloc with 80% feed (T4). The biofloc‐based treatments showed significantly higher floc volume, total suspended solids, total heterotrophic bacteria and plankton density than the control (p &lt; 0.05). All the growth parameters were significantly higher in biofloc‐based treatments (T2, T3 and T4) than in the control (T1). The lowest feed conversion ratio was found lowest in T4 (1.40 ± 0.02) and highest in T1 (2.13 ± 0.04), which was significantly different among the treatments (p &lt; 0.05). The significantly highest production was obtained 939.02 ± 6.61 kg/ha in T2, and the lowest was 779.67 ± 7.50 kg/ha in T1. The length–weight relationship indicated positive allometric growth in all treatments. The condition factor ranged from 0.95 to 1.07, showing that the prawns were in good health throughout all treatments. The results of the present study indicated that M. rosenbergii can adapt to a biofloc‐based aquaculture system, and the conventional feeding rations can be reduced up to 20% without affecting the growth and production.

Enhancing brackish water tilapia seed production with biofloc technology

Aim of this study was to observe the effect of biofloc technology application to enhance brackish water tilapia production. This research was conducted by using two different stocking densities at 3000 seeds.m-3 (D-3000) and 6000 seeds.m-3 (D-6000). It was performed on concrete tanks of 5.5 x 1.8 x 0.8 m in dimension (active volume 5 m3) located under semi-indoor building. Biofloc formation were stimulated by adding molasses as carbon source by adjusting C:N ratio to around 10:1. The water salinity increased gradually after 8th day and reached up to 15 ppt during harvest. The result showed that brackish water tilapia seed survival rate of D-3000 and D-6000 was in range 77-79 %, biomass were 0.60 - 0.85 kg.m−3, and seed uniformity was 77-82%. Biofloc or floc volume of D-3000 was higher than D-6000 at 10 ml.l−1 and 3 ml.l−1 respectively. At the beginning, microalgae population was dominated by Bacillariophyceae while Chlorophyceae dominated at the end of rearing periods, and Rotifer density around 64-191 ind.ml−1. Total bacteria observed was in range of 3x103-14x104 cfu.ml−1. For both treatment nitrite (N-NO2) was 0.000-0.029 ppm, nitrate (N-NO3) was 0.000-0.445 ppm or less than 0.5 ppm, dissolved oxygen (DO) range was in optimal conditions (5.8-6.2 ppm) for tilapia rearing.

Effect of pH value on effectiveness of biopolymer-based treatment of bauxite mine slurry

Effective dehydration and flocculation of mine slurries or sludge is important for nonferrous metal industries and environmental engineering. However, the mechanisms for the flocculation of slurry remain largely unclear. This paper presents the results of a series of flocculation tests, which was conducted on the slurry suspensions treated by xanthan gum (flocculant) at different pH values. It is shown that the settlement rate of mine slurry particles can be accelerated by adding xanthan gum, and the maximum sedimentation rate was obtained at a pH value of 5.9, and the final volume of flocs is significantly increased due to the addition of the flocculant. In addition, the settlement rates of xanthan gum-treated slurry suspensions at the pH values of 3, 5 and 7 decrease slightly compared with the reference slurry suspensions with pH=5.9, and the slurries remained stable as suspensions at the pH value of 9 and 11. The zeta potential measurement and SEM image analysis show that flocculation occurs primarily due to electrostatic attraction between slurry particles and the flocculants, and the bridging effect between the carboxylic groups in the side chains of xanthan gum molecule and the suspension particles.

Valorisation of aquaculture sludge into microbial protein using bioreactor with an optimised nutrients

The present study was conducted to optimise the nutrients used for producing high nutritional biofloc in bioreactor utilising aquaculture waste. Full Factorial design (23) of independent variables such as sludge quantity (20 and 30 gL−1), carbon nitrogen ratio (15:1 and 20:1) and bioflocculant (cationic starch) doses (30 and 60 ppm) were used for optimisation. The percentage of crude protein and crude lipid in biofloc was shown to be significantly influenced by the interaction between carbon nitrogen ratio and bioflocculant dose (BC) as well as the interaction between sludge quantity, carbon nitrogen ratio, and bioflocculant dose (ABC) (p < 0.05). The floc volume of biofloc was shown to be significantly influenced by the interaction between carbon nitrogen ratio and bioflocculant dose (BC) (p < 0.05). The optimised parameters were 30 gL−1 of sludge, a carbon nitrogen ratio of 20:1, and 30 ppm of cationic starch, which resulted in a maximum CP of 27.09%, a maximum CL of 4.36%, and a maximum floc volume of 132 mL L−1. Principal component analysis (PCA) resulted in a 2 principal components (PC 1, nutritional factors which decides the nutritional composition of biofloc and PC 2, nitrification factors which are needed for biofloc formation) that explained 85% of total data variation. This study found the production of nutritive biofloc in a bioreactor using aquaculture waste with optimised nutrients.

A step toward a biofloc system with no‐carbon addition: Increasing dietary lipid level enhances the water quality and body chemical composition without affecting tilapia health status

AbstractA 70‐day experiment was carried out to evaluate biofloc system operation with no carbon addition by manipulating dietary protein and lipid levels for Nile tilapia (Oreochromis niloticus) cultivation. Three treatments were conducted; Control treatment (C; fed on a 30% crude protein [CP] diet supplemented with 3% vegetable oil [VO] + addition of external carbon source [ECS] in rearing tank), low protein–low lipid treatment (LPLL; fed on 23% CP diet supplemented with 3% (VO) + no addition of ECS) and low protein–high lipid treatment (LPHL; fed on 23% CP diet supplemented with 9% VO + no addition of ECS). The C treatment recorded the highest values (p &lt; 0.05) in terms of final body weight (FBW), specific growth rate, floc volume, total suspended solids, and ammonia nitrogen. No significant differences were observed between C and LPHL treatments regarding FBW and protein efficiency ratio. The liver sections of LPHL treatment showed better values for histological alteration index compared to the control. It could be concluded that applying a biofloc system with no carbon addition using LPHL diets may afford better water quality conditions, limit the environmental impact and decrease dietary costs with limited effect on fish performance.

Design and Development a Smart Control System for Temperature and Turbidity of Bio Floc Fish Ponds

Bio floc aquaculture techniques are present as a solution to increase the productivity of fish farming. However, until now there are still problems, namely regarding the quality of the water from the pond. In this study, a monitoring tool was designed using an ESP32 microcontroller with the support of a BME280 sensor, RTD PT100 to measure water temperature and a turbidity sensor to measure floc volume. Furthermore, this sensor is planted on Wi-Fi to be able to connect to the internet network for IoT applications so that it can be monitored in real time. Likewise, the display results from the monitoring of the application system are directly read on the Google sheet display and in real time. From the test results of the system built, obtained the accuracy level of the BME280 sensor is 96.5%, PT100 RTD is 94.6% and for the turbidity sensor is 98%. Meanwhile the observed air temperature value can reach 34.36°C, the water temperature reaches 28.75°C, and the floc ratio reaches 30.15 mL.L-1. From the results shown, it clearly indicates that the water quality monitoring system has been successful and is working very well.

Growth Performance and Survival of Climbing Perch (Anabas testudineus Bloch) Raised in Conventional and Bioflocs System

The aim of this research is to analyze the performance of growth and survival of climbing perch (Anabas testudineus Bloch) which was raised in bioflocs and conventional systems. It investigated the difference in the initial size of the fry stocked with climbing perch has effect. The experimental design used in this study was a Factorial Completely Randomized Design (CRD) with 2 factors and 3 replications: Factor A: climbing perch aquaculture Systems; A1: climbing perch in conventional system of; A2: the climbing perch in bioflocs system; Factor B: Initial Size of fry Stocking; B1: fry size 3 ± 0.5cm; B2: fry size 5 ± 0.5cm and B3: fry size 7 ± 0.5cm. The research was conducted for 90 days with daily growth parameters (SGR), weight and length growth, survival rate, food conversion, flocsvolume density (FVD), and main water quality parameters (water temperature, pH, dissolved oxygen and dissolved ammonia).The results showed that the bioflocs system was able to increase the average growth in the range of 12-67% with an average of 29.73% when compared to conventional systems. The highest value for the daily growth rate or Specific Growth Rate (%/day) was for fry with a size of 7 cm in the bioflocs system (8,419%). The fry size of 3 ± 0.5cm in the bioflocs system had the highest difference in standard length (4.33 cm) while the highest average length during maintenance was the seed size of 7 ± 0.5 cm in the bioflocs system. The survival results of climbing perch fish during the study were based on the highest score on the seed size of 3 ± 0.5cm in the bioflocs system. The survival range of the bioflocs system is 94.89 - 99.67% and that of the conventional system is 82.00 - 94.26%. Thus the bioflocs system is able to increase survival in the range of 5-14% when compared to conventional systems. The bioflocs system is able to provide better feed efficiency than conventional systems in the range of 34-39%. The average value of floc volume density (FVD) in the bioflocs system is in the range of 5.35 – 8.16 ml/L, which is still ideal but can still be improved. Water temperature during the study period, air and water temperatures ranged from 28.54 to 28.71 (ºC), the degree of acidity in all treatments was in the range 6.34 – 7.27, dissolved oxygen levels were in the range 5.77 – 6.90 mg /L) while the average measurement results for ammonia levels (mg/L) were in the range of 0.49 – 0.57 mg/L. The temperature ranges in the studies on conventional and bioflocs systems are within the acceptable range for fish farming Water temperature during the study period, air and water temperatures ranged from 28.54 to 28.71 (ºC), the degree of acidity in all treatments was in the range 6.34 – 7.27, dissolved oxygen levels were in the range 5.77 – 6.90 mg /L) while the average measurement results for ammonia levels (mg/L) were in the range of 0.49 – 0.57 mg/L.

Modified biofloc technology and its effects on water quality and growth of catfish

ABSTRACT Biofloc-based Catfish (Clarias batrachus) farming allows for improving water quality, and growth. To further optimize the biofloc technology, we modified it with carbonation and bio balls to improve the C/N ratio and the performance of the floc-forming bacterial consortium. The purpose of this study is to analyze several parameters such as floc volume, BOD (biological oxygen demand), COD(chemical oxygen demand), BOD/COD, TOM (total organic matter), TDS(total dissolved suspended), orthophosphate, sulfate. SGR(specific growth rate), FE(feed efficiency), FCR(feed conversion ratio), SR (survival rate) and to obtain appropriate and environmentally friendly technology that can be applied in producing Catfish based on biofloc. In this study, a completely randomized design was used with 5 treatments and 4 replications, From the results of the study obtained: floc volume (76–88 mL L−1), BOD (2.152–2.367 mg L−1), COD (5.462–7.312 mg L−1), BOD/COD (0.324–0.394), TOM (5.1–19.2 mg L−1), TDS (318–1560 mg L−1), orthophosphate (0.7–9.1 mg L−1), sulfate (18.1–34.0 mg L−1), SGR (0.058–0.066), FE (90.89–98.79%), FCR (0.933–1.104), SR (84–88%). In the future, the application of a combination of carbonation and bio balls in Catfish farming based on biofloc is feasible to be developed.

Analysis of aerobic granulation trigger driving mechanism under different organic substrate diffusibility based on microfluidic system

In the present study, the effects of the different molecular weight organic substrates on the sludge granulation were investigated. The operation of the reactor was combined with the microfluidic chip technology to analyze the relationship between the microscopic phenomena, physicochemical properties of the granular sludge, and reactor performance in the process of sludge granulation. The use of starch, which has flocculation properties, and sodium glutamate as carbon source contributed to good settleability. The high permeability of sodium acetate and sodium propionate led to fluffy granules with an unstable settleability but a rapid size growth. From the microfluidic experiments, it was found that the sludge flocs secreted yellowish substances, which increased the overall floc volume and promoted mutual adhesion between the individual flocs. The changes in the PN/PS and Zeta potential were consistent with the trend in the sludge volume in the microfluid. The extracellular polymeric substances, and other secretions containing new cells of sludge, reduced the surface potential to enhance the flocculation process and were the key products of the conversion into aerobic granular sludge.

Effect of addition of carbon and probiotics on water quality, production performance, and health of catfish (Clarias gariepinus) in biofloc systems

This study aimed to evaluate the use of organic carbon and probiotics on water quality, production performance, and haematological status in sangkuriang catfish. This experiment used a completely randomized design with four treatments: addition of organic carbon (C), the addition of probiotics (P), the addition of organic carbon and probiotics (CP), and control (K), each treatment with three replications. Catfish seeds measuring 1.86±0.60g 500 tails were stocked in a 1m3 pond. The seeds were fed commercial feed with a dose of 5% of the biomass. The results showed that the four treatments pH, dissolved oxygen, nitrite, and the bacterial population, had no significant effect. In contrast, TSS, TAN, and floc volume had a significant effect but were still in a good range of growth catfish. Specific growth rate, absolute growth, and final weight were higher in adding organic carbon (C) and (CP), survival, and the best feed conversion ratio in addition to organic carbon and probiotics than in control. Low haemoglobin and erythrocyte values were indicated as the cause of fish death. Based on the study's results, it can be concluded that adding organic carbon to the experimental pond can increase the specific growth rate. Adding organic carbon and probiotics increased survival and final weight but decreased the best feed conversion ratio compared to controls. Therefore, from the study results, it is enough for fish cultivators to utilize the addition of organic carbon to provide the best growth for fish cultured in a biofloc system.

A Semi-Empirical Model to Estimate Maximum Floc Size in a Turbulent Flow.

The basic model for agglomerate breakage under the effect of hydrodynamic stress (dmax = C.G−γ) is only applicable for low velocity gradients (<500 s−1) and is often used for shear rates that are not representative of the global phenomenon. This paper presents a semi-empirical model that is able to predict mean floc size in a very broad shear range spanning from aggregation to floc fragmentation. Theoretical details and modifications relating to the orthokinetic flocculation output are also provided. Modelling changes in turbidity in relation to the velocity gradient with this model offer a mechanistic approach and provide kinetic agglomeration and breakage index ka and kb. The floc breakage mode is described by the relationship between the floc size and the Kolmogorov microscale. Shear-related floc restructuring is analysed by monitoring the fractal dimension. These models, as well as those used to determine floc porosity, density and volume fraction, are validated by the experimental results obtained from several flocculation operations conducted on ultrafine kaolin in a 4-litre reactor tank compliant with laws of geometric similarity. The velocity gradient range explored was from 60 to 6000 s−1.