Microbial Granules Research Articles

Aerobic granular sludge formation and stability in enhanced biological phosphorus removal system under antibiotics pressure: Performance, granulation mechanism, and microbial successions

Wastewater containing antibiotics can pose a significant threat to biological wastewater treatment processes. This study investigated the establishment and stable operation of enhanced biological phosphorus removal (EBPR) by aerobic granular sludge (AGS) under mixed stress conditions induced by tetracycline (TC), sulfamethoxazole (SMX), ofloxacin (OFL), and roxithromycin (ROX). The results show that the AGS system was efficient in removing TP (98.0%), COD (96.1%), and NH4+-N (99.6%). The average removal efficiencies of the four antibiotics were 79.17% (TC), 70.86% (SMX), 25.73% (OFL), and 88.93% (ROX), respectively. The microorganisms in the AGS system secreted more polysaccharides, which contributed to the reactor's tolerance to antibiotics and facilitated granulation by enhancing the production of protein, particularly loosely bound protein. Illumina MiSeq sequencing revealed that putative phosphate accumulating organisms (PAOs)-related genera (Pseudomonas and Flavobacterium) were enormously beneficial to the mature AGS for TP removal. Based on the analysis of extracellular polymeric substances, extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory, and microbial community, a three-stage granulation mechanism was proposed including adaption to the stress environment, formation of early aggregates and maturation of PAOs enriched microbial granules. Overall, the study demonstrated the stability of EBPR-AGS under mixed antibiotics pressure, providing insight into the granulation mechanism and the potential use of AGS for wastewater treatment containing antibiotics.

Microbial Granule Technology—Prospects for Wastewater Treatment and Energy Production

Recent years have brought significant evolution and changes in wastewater treatment systems. New solutions are sought to improve treatment efficiency, reduce investment/operational costs, and comply with the principles of circular economy and zero waste. Microbial granules can serve as an alternative to conventional technologies. Indeed, there has been fast-growing interest in methods harnessing aerobic (AGS) and anaerobic (AnGS) granular sludge as well as microbial-bacterial granules (MBGS), as evidenced by the number of studies on the subject and commercial installations developed. The present paper identifies the strengths and weaknesses of wastewater treatment systems based on granular sludge (GS) and their potential for energy production, with a particular focus on establishing the R&D activities required for further advance of these technologies. In particular, the impact of granules on bioenergy conversion, including bio-oil recovery efficiency and biomethane/biohydrogen yields, and bioelectrochemical systems must be assessed and optimized.

In-situ removal of residual antibiotics (enrofloxacin) in recirculating aquaculture system: Effect of ultraviolet photolysis plus biodegradation using immobilized microbial granules

The misuse of antibiotics and ineffective treatment in aquaculture cause serious environmental problems. The closed-loop design of recirculating aquaculture systems (RAS) enables the effective use of antibiotics and rapid removal of antibiotic residues. Hitherto, few studies have been carried out on these. This study aims to examine the feasibility of rapid in-situ removal of residual antibiotics in RAS using integrated process and characterize the operational parameters. The fate of the selected antibiotic enrofloxacin (ENR) in different units of a laboratory-scale RAS was investigated with photolysis pretreatment followed adsorption-biodegradation of photolysis intermediates by immobilized microgranules. The degradation kinetics was also characterized. The results indicated that the ultraviolet (UV) device in RAS played an important role in ENR removal. The wavelength and light intensity were crucial for the removal efficiency of ENR. The F− produced by defluorination could reproduce the effect of the decomposition of ENR by UV photolysis. The UV photolysis products of ENR had a positive relationship with photolysis time, indicating incomplete decomposition of ENR. Under optimal condition (UV 80 W/254 nm and flow rate of 60 L/h), the ratio of BOD5 to COD (B/C) after photolysis increased from 0.041 to 0.28, which supported biodegradation. The photolysis products were partially adsorbed by activated carbons in the immobilized microbial granules and then biodegraded by microbes of the granules. Based on this study, a four-step process was proposed for the control of residual antibiotics in RAS.

Production and compatibility assessment of denitrifying biogranules tailored for self-healing concrete applications

Microbial granules have been mostly used for wastewater treatment. Recently, biogranules consisting nitrate-reducing microorganisms have appeared as a unique healing agent providing simultaneous self-healing of cracks and corrosion inhibition of rebar in concrete. Yet, information about the production process and microbial activity of these biogranules as well as their compatibility with cementitious materials remains unknown. This study presents the biogranule production procedure in detail and evaluates the compatibility of the produced biogranules with the cementitious composites. In the form of biogranules, bacteria doses varying between 0.25% and 3.00% w/w cement were incorporated into mortar and the variations in fresh and hardened properties of mortars were evaluated with respect to abiotic mortars. Biogranules were also tested for their compatibility with concrete at minimum and the defined maximum tolerable doses. Biogranules with a NOx-N reduction activity of 0.10 g NOx-N.g−1 bacteria.d−1 and organic carbon oxidation activity of 1.50 g HCOO⁻.g−1 bacteria.d−1 were produced successfully by using minimal medium. It was found out that biogranules enable bacteria incorporation into mortar up to a dose of 2.50% w/w cement without compromising fresh and hardened properties of cementitious composites. It was revealed that the compatibility of the biogranules was due to the mineral layer surrounding the biogranules which prevented interaction between the cement matrix and the microbial content. The thickness of the protective mineral layer around the granules was varying between 50 and 300 μm depending on the granule size. Net yield for concrete compatible biogranule production was determined as 0.05 g biogranule.g−1 HCOO⁻.

Functional metagenomic analysis of quorum sensing signaling in a nitrifying community

Quorum sensing (QS) can function to shape the microbial community interactions, composition, and function. In wastewater treatment systems, acylated homoserine lactone (AHL)-based QS has been correlated with the conversion of floccular biomass into microbial granules, as well as EPS production and the nitrogen removal process. However, the role of QS in such complex communities is still not fully understood, including the QS-proficient taxa and the functional QS genes involved. To address these questions, we performed a metagenomic screen for AHL genes in an activated sludge microbial community from the Ulu Pandan wastewater treatment plant (WWTP) in Singapore followed by functional validation of luxI activity using AHL biosensors and LC–MSMS profiling. We identified 13 luxI and 30 luxR homologs from the activated sludge metagenome. Of those genes, two represented a cognate pair of luxIR genes belonging to a Nitrospira spp. and those genes were demonstrated to be functionally active. The LuxI homolog synthesized AHLs that were consistent with the dominant AHLs in the activated sludge system. Furthermore, the LuxR homolog was shown to bind to and induce expression of the luxI promoter, suggesting this represents an autoinduction feedback system, characteristic of QS circuits. Additionally, a second, active promoter was upstream of a gene encoding a protein with a GGDEF/EAL domain, commonly associated with modulating the intracellular concentration of the secondary messenger, c-di-GMP. Thus, the metagenomic approach used here was demonstrated to effectively identify functional QS genes and suggests that Nitrospira spp. maybe QS is active in the activated sludge community.

Development of biogenic bimetallic Pd/Fe nanoparticle–impregnated aerobic microbial granules with potential for dye removal

The objective of this study was to develop bimetallic core–shell Pd/Fe nanoparticles on the surface of aerobic microbial granules (Bio-Pd/Fe) and to evaluate their dye removal potential using a representative dye, methyl orange (MO). The aerobic microbial granules (1.5 ± 0.32 mm) were grown for 70 days in a 3-L glass sequencing batch reactor (SBR) with a 12-h cycle time. The Bio-Pd/Fe formation was catalyzed by the Bio-H2 gas produced by the granules. The developed Bio-Pd/Fe was further used for MO removal from aqueous solutions, and the reaction parameters were optimized by response surface methodology (RSM). The XRD, SEM, EDAX, elemental mapping, and XPS studies confirmed the formation of Bio-Pd/Fe. Under the optimized removal conditions, 99.33% MO could be removed by Bio-Pd/Fe, whereas removal by Bio-Pd, Bio-Fe, aerobic microbial granules, and heat-killed granules were found to be quite low (68.91 ± 0.2%, 76.8 ± 0.3%, 19.8 ± 0.6%, and 6.59 ± 0.2%, respectively). The mechanism of removal was investigated by UV–visible spectroscopy, redox potential analysis, HR-LCMS analyses of the solution phase, and XRD and XPS analyses of the solid sorbent. The degradation products of MO exhibited m/z values corresponding to 292, 212, and 160 m/z. The remnant toxicity of the intermediate degradation products was analysed using freshwater algae, Scenedesmus sp. And Allium cepa, as indicator organisms. These assays suggested that after the treatment with Bio-Pd/Fe, MO was transformed to a lesser toxic form.

High process activity of a two-phase UASB (upflow anaerobic sludge blanket) receiving ethanol wastewater: Operational conditions in relation to granulation development

The high process activity of a two-phase UASB (upflow anaerobic sludge blanket) system receiving ethanol wastewater was achieved in conjunction with sludge granulation. The optimal OLR (organic loading rate), as expressed in COD load of feed and overall effective liquid holding capacity, was found to be 32 kg m−3 d−1 with a mean granule diameter of 1.12 mm and granule density of 1.23 kg m−3. The system yielded a very high process effectiveness, as indicated in a high specific CH4 production rate (11.83 m3 CH4·mR−3 ·d−1) and a high total COD removal of above 90%. Moreover, the system showed the total energy yield was very high as 15,840 kJ kg−1 COD applied with the energy extraction efficiency of 82.5%. The sludge granulation seemed to begin and was clearly observed at high OLRs of 24 and 28 kg m−3 d−1, respectively. Apart from the long time operation (about 2 y) with a slowly increased rate of OLR, causing the accumulation of metal sulfide particles to act as nuclei to facilitate for the formation of microbial granules, the low pH of 5.5 in the primary reactor was responsible for avoiding the micronutrient deficit situation which, in turn, became a main factor in the success of granulation in the investigated two-phase UASB. The presence of lactic acid (HLa) in the secondary reactor can be used to indicate the system overload and process instability. The inhibition levels of total volatile fatty acids (VFA) to acidogens and methanogens were about 9,000 and 400 mg L−1 as acetic acid (HAc), respectively.

Biohydrogen production in a continuous liquid/gas hollow fiber membrane bioreactor: Efficient retention of hydrogen producing bacteria via granule and biofilm formation

The aim of this work was to develop a continuous liquid/gas membrane bioreactor (L/G MBR), i.e. a fermenting module including hollow fibers membrane for L/G separation, for biohydrogen production by dark fermentation. Originally seeded with sludge from a wastewater treatment plant, the L/G MBR underwent a complete stop for eight months. It was then operated without further reseeding. In the present experiment, performed 551 days after the last reseeding, average hydrogen yield of 1.1 ± 0.2 mol per mol glucose added and hydrogen productivity of 135 ± 22 mL/L/h were reached, with acetate and butyrate as the main metabolite products. DNA sequence analysis revealed that Clostridium beijerinckii, Clostridium pasteurianum and Enterobacter sp. were dominant in liquid outlet, in a biofilm on the surface of the hollow fibers and in microbial granules. The L/G MBR has potential for the concentration and the long-term maintenance of an active hydrogen-producing bacterial community without need for reseeding.

Development of Aerobic Microbial Granules to Enhance the Performance of Activated Sludge Technology for Wastewater Treatment Application

Batik industry is one of textile industries in Indonesia generally in small and medium scale and has not good management of by-products in the form of wastewater. Wastewater from batik industry consist of complex and toxic pollutants hence need to be treated in order to support the development of environmentally friendly sustainable industry. Some researches have treated batik wastewater using conventional biological treatment such as anaerobic and activated sludge but optimal results have not been obtained. This research aims to develop a compact aerobic microbial granule with good endurance, which also rich in carbon and nutrient oxidizer bacteria to treat batik wastewater. Sequencing Batch Reactor (SBR) with volume of 8 L fed with Acetate (COD = 900-1000mg/L), then aerated for 180 minutes. Settling time variation was from 20 to 3 minutes, with 50% liquid withdrawal. In the 4 weeks operation there is increasing of MLVSS reached on 4760 mg/L with COD removal reach on 91,94%. The depletion of dissolved oxygen take effect on decreasing of MLVSS and COD removal.

Effect of aquaculture salinity on nitrification and microbial community in moving bed bioreactors with immobilized microbial granules

The novel immobilized microbial granules (IMG) shows a significant effect of nitrification for freshwater aquaculture. However, there is lack of evaluation study on the performance of nitrification at high salinity due to the concentration of recycled water or seawater utilization. A laboratory scale moving bed bioreactor (MBBR) with IMG was tested on recycled synthetic aquaculture wastewater for the nitrification at 2.5 mg/L NH3-N daily. The results indicated that IMG showed a high salinity tolerance and effectively converted ammonia to nitrate up to 92% at high salinity of 35.0 g/L NaCl. As salinity increased from near zero to 35.0 g/L, the microbial activity of nitrite oxidation bacteria (NOB) in the IMG decreased by 86.32%. The microbial community analysis indicated that salinity significantly influenced the community structure. It was found that Nitrosomonas sp. and Nitrospira sp. were the dominant genera for ammonia oxidation bacteria (AOB) and NOB respectively at different salinity levels.

Anaerobic nano zero-valent iron granules for hexavalent chromium removal from aqueous solution

Abstract The current study reports environmental application of zero-valent iron nanoparticles (NZVI)-laden anaerobic microbial granules for the removal of a major environmental pollutant, Cr (VI), from aqueous solutions. The anaerobic NZVI granules were characterized using X-ray diffraction, SEM, EDX, and FTIR analyses. For Cr (VI) removal experiments, Box–Behnken Design (BBD) with three-level factors was applied. The three operating variables, with the highest influence on Cr(VI) removal were initial concentration of Cr(VI), reaction time, and anaerobic NZVI granule dry weight. A very high removal capacity of 296.7 ± 1.82 mg/g was observed with the optimized conditions (Cr (VI) Initial concentration: 10 mg/L; anaerobic NZVI granule weight dry weight: 50 mg; reaction time: 90 min). The reduction kinetics followed pseudo-second-order model. The residual toxicity of the effluent solution after treating with the anaerobic NZVI granules was examined using microalgae, artemia, and Allium bioassays, proving a significant detoxification obtained using the process. The feasibility of using the anaerobic NZVI granules for removal of Cr (VI) from real water systems was further confirmed using groundwater and lake water samples spiked with Cr (VI). The Cr (VI) removal was noted at 88 ± 1.56 % with 231.7 ± 1.21 mg/g capacity, whereas in the lake water, they were estimated to be 79 ± 1.94 % and 217 ± 0.91 mg/g respectively, with the optimized conditions (Cr (VI) concentration added in real water system: 10 mg/L; anaerobic NZVI granule dry weight: 50 mg; reaction time: 90 min).

Pore characteristics of different organic matter in black shale: A case study of the Wufeng-Longmaxi Formation in the Southeast Sichuan Basin, China

Organic matter (OM) pores are recognized to be the most important pore type in gas shales in the Ordovician Wufeng-Silurian Longmaxi Formation in the Sichuan Basin, China. However, the effects of the type and origin of organic matter on pore development in OM remain controversial. In this study, detailed scanning electron microscope (SEM) analysis of siliceous shales was conducted for core samples from the Wufeng-Longmaxi Formation, taken from five shale gas wells in the Southeast Sichuan Basin. In addition to bitumen, several types of morphologically distinct organic macerals were identified. Due to the high maturity (vitrinite reflectance (Ro) > 2.2%) and compaction of the sample, confirming the origin of some OM types was difficult. However, each OM type is characterized by distinct pore features: (1) the pores in bitumen are normally well developed, with circular or irregular shapes; (2) spherical kerogen contains uneven pores, with irregular and angular pores at the periphery and few pores in the core; (3) algal fragments may have angular pores, the distribution and structure of which are influenced by the initial structure of the organic matter; (4) bacteria-like aggregates represent the accumulation of numerous microbial granules, and contain residual pores; (5) graptolites are relatively tight and usually have few or no pores. The findings indicate that bitumen and algal fragments are the most favourable hydrocarbon-generating organisms for OM pore development. Notably, organic matter originating from different biological sources can influence the extent, shape, and structure of the pores. Some organic pores are recognized as remained pores of sedimentary stage, which may be previously regarded as pores formed during the gas generation period.

Experimental and numerical analysis on the hydrodynamic behaviors of permeable microbial granules

The microbial granules are found to be porous and permeable, which leads to a different drag force coefficient from the rigid sphere granules. Discrete element method (DEM) was employed to establish geometric models of porous microbial granules for the first time in this study. And computational fluid dynamics (CFD) was applied to simulate the effects of porosity and Reynolds number on the fluid flow, shear stress, pressure and drag force based on the established geometric models. The results showed that both the Reynolds number and the porosity of microbial granules significantly affect the fluid velocity distribution inside the granules. The porosity shows less effect on maximum shear stress than Reynolds number. It s well known that drag force consists form drag and skin drag. The ratio of form drag to drag force increased, while the skin drag force ratio decreased with the increasing Reynolds number. The porosity will enhance the skin drag and weaken the form drag at the same Reynolds number. A drag force coefficient equation was established based on the simulated results in order for engineering application. The correctness of the equation was confirmed by comparing with experimental results. The results from this study may provide valuable information for operation and designing of a granule-based bioreactor in wastewater treatment.

Performance of Aerobic Microbial Granules in Organic Carbon Removal as a Method in the Treatment of Biodegradable Wastewater

Conventional biological wastewater treatment is effective in removing organic carbon but has weaknesses in need large area, long hydraulic retention time, produce excess sludge in activated sludge system and need post treatment for removing nutrient in the anaerobic system. Aerobic microbial granules is a biological method in wastewater treatment that potential to overcome the lack of conventional biological treatment. Aerobic granules were developed in SBR made of glass with an effective volume of 10 L. Acetate was used as a source of carbon with COD concentration 900-1200 mg/L. SBR was run in anaerobic and aerobic phase with a hydraulic retention time of 8,3 hours and an exchange ratio of 60%. Granules begin to be formed after 14 days operational period with SVI30 to SVI5 ratio reach on 0,97 and settling velocity 13,8 cm/minute. High performance in degrading organic carbon is shown by aerobic microbial granules system with removal efficiency reaches on 94-97%.

Biodiesel production from microbial granules in sequencing batch reactor

Effect of reaction variables of in situ transesterification on the biodiesel production, and the characteristic differences of biodiesel obtained from aerobic granular sludge (AG) and algae-bacteria granular consortia (AAG) were investigated. The results indicated that the effect of variables on the biodiesel yield decreased in the order of methanol quantity > catalyst concentration > reaction time, yet the parameters change will not significantly affect biodiesel properties. The maximum biodiesel yield of AAG was 66.21 ± 1.08 mg/g SS, what is significant higher than that of AG (35.44 ± 0.92 mg/g SS). Although methyl palmitate was the dominated composition of biodiesel obtained from both granules, poly-unsaturated fatty acid in the AAG showed a higher percentage (21.86%) than AG (1.2%) due to Scenedesmus addition. Further, microbial analysis confirmed that the composition of biodiesel obtained from microbial granules was also determined by bacterial community, and Xanthomonadaceae and Rhodobacteraceae were the dominant bacteria of AG and AAG, respectively.

Fast anaerobic sludge granulation at elevated salinity

It is commonly accepted that high salt concentrations negatively affect microbial activity in biological wastewater treatment reactors such as upflow anaerobic sludge blanket (UASB) reactors. Microbial aggregation in such reactors is equally important. It is well documented that anaerobic granules, when exposed to high salinity become weak and disintegrate, causing wash-out, operational problems and decreasing process performance. In this research, the possibility of microbial granule formation from dispersed biomass was investigated at salinity levels of 5 and 20 g Na+/L. High removal efficiencies of soluble influent organics were achieved at both salinity levels and this was accompanied by fast and robust formation of microbial granules. The process was found to be stable for the entire operational period of 217 days. As far as we know this is the first time it has been demonstrated that stable granule formation is possible at a salinity level as high as 20 g Na+/L. Methanosaeta was identified as the dominant methanogen at both salinity levels. Streptococcus spp. and bacteria belonging to the family Lachnospiraceae were identified as the dominant microbial population at 5 and 20 and g Na+/L, respectively.

Role of CODPCP/CODTotal ratio on p-chlorophenol toxicity towards aerobic granular sludge

Abstract Aerobic granular sludge (AGS) has emerged as a promising biotechnology for the treatment of industrial wastewaters. The biodegradation of AGS utilizing p-chlorophenol (PCP) was investigated under various CODPCP/CODTotal ratios. The initially developed microbial granules were used for degradation of PCP, with monoethylene glycol (MEG) as co-substrate. Heterotrophic bacteria in AGS appeared to adapt fairly rapidly to PCP, and a near complete recovery of their metabolic activity was noticed after about 4 d of exposure to high PCP levels (up to 400 mg/L). Nevertheless, CODPCP/CODTotal ≥ 0.648 did negatively affect granular sludge in terms of both morphology and biological activity.

Microbial Population Dynamics and Ecosystem Functions of Anoxic/Aerobic Granular Sludge in Sequencing Batch Reactors Operated at Different Organic Loading Rates.

The granular sludge process is an effective, low-footprint alternative to conventional activated sludge wastewater treatment. The architecture of the microbial granules allows the co-existence of different functional groups, e.g., nitrifying and denitrifying communities, which permits compact reactor design. However, little is known about the factors influencing community assembly in granular sludge, such as the effects of reactor operation strategies and influent wastewater composition. Here, we analyze the development of the microbiomes in parallel laboratory-scale anoxic/aerobic granular sludge reactors operated at low (0.9 kg m-3d-1), moderate (1.9 kg m-3d-1) and high (3.7 kg m-3d-1) organic loading rates (OLRs) and the same ammonium loading rate (0.2 kg NH4-N m-3d-1) for 84 days. Complete removal of organic carbon and ammonium was achieved in all three reactors after start-up, while the nitrogen removal (denitrification) efficiency increased with the OLR: 0% at low, 38% at moderate, and 66% at high loading rate. The bacterial communities at different loading rates diverged rapidly after start-up and showed less than 50% similarity after 6 days, and below 40% similarity after 84 days. The three reactor microbiomes were dominated by different genera (mainly Meganema, Thauera, Paracoccus, and Zoogloea), but these genera have similar ecosystem functions of EPS production, denitrification and polyhydroxyalkanoate (PHA) storage. Many less abundant but persistent taxa were also detected within these functional groups. The bacterial communities were functionally redundant irrespective of the loading rate applied. At steady-state reactor operation, the identity of the core community members was rather stable, but their relative abundances changed considerably over time. Furthermore, nitrifying bacteria were low in relative abundance and diversity in all reactors, despite their large contribution to nitrogen turnover. The results suggest that the OLR has considerable impact on the composition of the granular sludge communities, but also that the granule communities can be dynamic even at steady-state reactor operation due to high functional redundancy of several key guilds. Knowledge about microbial diversity with specific functional guilds under different operating conditions can be important for engineers to predict the stability of reactor functions during the start-up and continued reactor operation.

Developed microbial granules containing photosynthetic pigments for carbon dioxide reduction in palm oil mill effluent

Since the photosynthetic process offers a natural way of sequestering carbon dioxide (CO2) from industrial wastewater treatment such as the ponding system to treat palm oil mill effluent (POME), microbial granules possessing photosynthetic pigments were developed in a sequencing batch reactor (SBR) system using POME. POME from the last pond was used as source of nutrients for the biogranulation process. The developed microbial granules had shown the potential of retaining high accumulation of biomass concentration in the reactor (6.90–8.25 g L−1), good settling properties (18.0–103.0 m h−1) and improvement in size collected ranging from 0.3 to 2.36 mm as well as physical strength at integrity coefficient of 2% with most of the granules retained in the last day were 1.4 mm. The pigment analysis indicated the presence of the bacteriochlorophyll a implying the presence of anoxygenic photosynthetic bacteria. However, it is important to note that the molecular identification of the bacteria showed the presence of Enterobacter cloacae, Bacillus cereus and Lysinibacillus sp. which are typically known to be non-photosynthetic. These bacteria were found to possess photosynthetic pigments, mainly bacteriochlorophyll a and carotenoids.

Reduction and biofixation of carbon dioxide in palm oil mill effluent using developed microbial granules containing photosynthetic pigments

The developed microbial granules containing photosynthetic pigments had successfully achieved approximately 18–21% of carbon dioxide (CO2) removal in POME for one complete SBR cycle. Also, the granules had reached CO2 removal at 15–29% within 24h and removal of 25% after 5 days. Both results were inconsistent possibly due to the slow mass transfer rate of CO2 from gas to liquid as well as the simultaneous effect of CO2 production and respiration among the microbes. Furthermore, results showed the removal of CO2 from air increases proportionally with the CO2 removed in liquid. The CO2 biofixation of granules attained was approximately 0.23g/L/day for a week. Using the regression model, the removal of CO2 between liquid and gas, CO2 biofixation rate were highly correlated with the treatment time. A statistically significant relationship was obtained between CO2 concentration in liquid, biomass productivity and treatment time for the CO2 biofixation rate of the granules.