Optimization of two-staged bio-hydrogen production by immobilized <i>Microcystis aeruginosa</i>

Rashid, Naim,Choi, Wookjin,Lee, Kisay Elsevier 2012 Biomass & bioenergy Vol.36 No.-

<P><B>Abstract</B></P><P>Two-staged bio-hydrogen production was investigated in <I>Microcystis aeruginosa</I>. Stage-I comprised aerobic growth of immobilized algal cells for three days while anaerobic conditions were established in stage-II by sulfur deprivation and photo inhibition under high light intensity. Hydrogen evolution was investigated under fully dark, fully light and partially dark conditions (24 h in dark and light thereafter) using diverse carbon sources and pH values. Full light proved to be most effective with a hydrogen volume of 490 ± 3 ml/L at an average rate of 9.42 ml/h/L. The growth period could be reduced to 2 days in fully dark and fully light conditions. The hydrogen evolution was optimum at pH 9.0 with malt extract as carbon source for <I>M. aeruginosa</I>. However, the optimum pH value was lowered to 8.0 when optical fiber was used as an internal light source during stage-I.</P> <P><B>Highlights</B></P><P>► We optimized two-stage hydrogen production by investigating the effects of light and carbon sources. ► Among various patterns of light, fully light condition proved to be most effective. ► The use of optical fiber slowed down the rate of hydrogen production. ► Malt extract resulted in maximum hydrogen production.</P>

Characteristics of hydrogen production by immobilized cyanobacterium Microcystis aeruginosa through cycles of photosynthesis and anaerobic incubation

Naim Rashid,Wei Song,Jongmin Park,Hai-Feng Jin,이기세 한국공업화학회 2009 Journal of Industrial and Engineering Chemistry Vol.15 No.4

The characteristics of hydrogen production using immobilized cyanobacterium Microcystis aeruginosa were studied through a two-stage cyclic process. Immobilized cells were first grown photosynthetically under CO2 and light, followed by anaerobic H2 production in the absence of light and sulfur. M. aeruginosa was capable of generating H2 under immobilized conditions, and the use of immobilized cells allowed the maintenance of stable production and sped up the changes in culture conditions for cyclic two-stage operation. M. aeruginosa was also capable of utilizing exogenous glucose as a substrate to generate hydrogen and 30 mM concentration proved to be optimal. The externally added glucose improved H2 production rates, total produced volume and the lag time required for cell adaptation prior to H2 evolution. The rate of hydrogen evolution was increased as temperature increased, and the maximum evolution rate was 48 mL/h/L and 34.0 mL/h/L at 42℃ and 37℃, respectively. The optimal temperature for hydrogen production was 37–40℃ because temperatures higher than 42℃ resulted in cell death. In order to continue repeated cycles of H2 production, at least two days of photosynthesis under conditions with light, CO2, and sulfur should be allowed for cells to recover H2 production potential and cell viability.

Hydrogen Production by Immobilized Sulfur-Deprived Cyanobacteria Microcystis aeruginosa under Different Conditions of Light Exposure and Glucose Addition

Rashid, Naim,Lee, Kisay 明知大學校 産業技術硏究所 2008 産業技術硏究所論文集 Vol.27 No.-

In this study, immobilized cyanobacteria was applied fur H₂production using two-stage operation consisted in photosynthetic growth under light and anaerobic H₂production at sulfur-deprived condition. After the addition of 30mM exogenic glucose, cells were incubated in three different conditions for comparison: (i) fully dark, (ii) partially dark (first 24 hours in the dark and light thereafter), and (iii) fully light conditions. The fully light condition resulted in the highest H₂production. The light exposure in early anaerobic stage was favorable for hydrogen production until anaerobic condition is completely established and, after that, a low light or dark condition is also acceptable. The photosynthetic growth period before anaerobic H₂production could be shortened from 3 days to 2 days successfully in fully light and fully dark condition. In case of partially dark condition, 3 days growth period was mandatory to recover cellular activity. Glucose has a direct relationship with the production of hydrogen, as hydrogen evolution increases with the utilization of glucose by the cell. It was advantageous to add glucose at the beginning of anaerobic incubation, instead of adding after 24 hours, as it is a limiting factor to the overall efficiency of hydrogen production.

Co-cultivation of two freshwater microalgae species to improve biomass productivity and biodiesel production

Rashid, Naim,Ryu, Ae Jin,Jeong, Ki Jun,Lee, Bongsoo,Chang, Yong-Keun Pergamon 2019 Energy Conversion and Management Vol. No.

<P><B>Abstract</B></P> <P>This study aimed to investigate the symbiotic relationship of two freshwater microalgae species, <I>Ettlia</I> sp. and <I>Chlorella</I> sp<I>.</I> HS-2 to improve biomass productivity<I>.</I> The species were co-cultivated autotrophically under the inoculation ratios (<I>Chlorella</I>/<I>Ettlia</I>) of 1:01, 1:04, 1:08, and 1:16. The performance of co-cultivation was compared with monoculture. It found that the co-cultivation returned higher biomass productivity (P < 0.05) than the monoculture under all inoculation ratios. The highest biomass productivity of 0.70 ± 0.02 g L<SUP>−1</SUP> day<SUP>−1</SUP> was achieved with an inoculation ratio of 1:08. The biomass productivity further increased to 0.74 ± 0.06 g L<SUP>−1</SUP> day<SUP>−1</SUP> by switching the cultivation mode to the mixotrophic condition. The biomass productivity of mixotrophic co-cultivation was higher P < 0.05 (0.74 ± 0.06 g L<SUP>−1</SUP> day<SUP>−1</SUP>) than the mixotrophic mono-culture of <I>Ettlia</I> (0.41 ± 0.06 g L<SUP>−1</SUP> day<SUP>−1</SUP>) but equal to mixotrophic mono-culture of <I>Chlorella</I>. FACS analysis revealed that the biomass obtained after co-cultivation contained 81% of <I>Chlorella</I> cells. In biochemical composition, co-cultivation (autotrophic) biomass contained protein 41%, carbohydrates 33%, lipids 11%, and pigments 2% of dry cell weight. The major fatty acids produced in the co-cultivation were C16–C18, which are favorable for biodiesel production. It is concluded that the co-cultivation is more favorable than the monoculture to obtain high biomass productivity and stable biomass composition.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Co-cultivation of two microalgae species (<I>Ettlia</I> and <I>Chlorella</I>) was tested. </LI> <LI> Co-cultivation returned the maximum biomass productivity at 1:08 inoculation ratio. </LI> <LI> Biomass productivity in mono-culture was 0.26 g L<SUP>−1</SUP> day<SUP>−1</SUP>. </LI> <LI> Biomass productivity in co-cultivation was 0.70 g L<SUP>−1</SUP> day<SUP>−1</SUP>. </LI> <LI> Co-cultivation was more effective in mixotrophic condition than autotrophic. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Effect of reduction of growth period in biological production of hydrogen by immobilized microalgae through alternating growth/production cycles

Naim Rashid,Wei Song,Ki Say Lee 대한환경공학회 2007 대한환경공학회 학술발표논문집 Vol.2007 No.12

Two-stage biohydrogen production by immobilized green algae Chlorella Vulgaris: Effects of pH and different carbon sources

( Naim Rashid ),이기세 한국공업화학회 2008 한국공업화학회 연구논문 초록집 Vol.2008 No.1

Chitosan as a Flocculant: An Approach to Improve its Solubility for Efficient Harvesting of Microalgae

( Attia Sajjad ),( Muhammad Rizwan ),( Ghulam Mujtaba ),( Naim Rashid ) 한국화학공학회 2017 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.55 No.4

Chitosan is a promising flocculant for microalgae harvesting, but its scale-up application is not economically supported yet. Low solubility of chitosan in microalgae suspension demands high dosage (as a flocculant) to destabilize the cells, and thus, increases the cost of microalgae harvesting. This study identifies efficient solvents for the chitosan, and optimizes the concentration of solvents and chitosan dose to improve the harvesting efficiency. Chitosan was dissolved in different acids, and subsequently used as a flocculant. The flocculant efficacy was measured in terms of harvesting efficiency and reduction in chemical oxygen demand (COD) of the microalgae suspension. It was found that chitosan dissolved in 0.05 M HCl showed the highest harvesting efficiency (89 ± 0.87%) at only 30 mg/L of dosage. In comparison, 270 mg/L of FeCl₃·6H₂O was required to attain 86 ± 0.083% of the harvesting efficiency. H₂SO₄ dissolved chitosan required high flocculant dose (150 mg/L) and resulted in relatively low harvesting efficiency (77±0.11%). It was concluded that the efficacy of chitosan is solvent dependent, and the selection of proper solvent can decrease the dosage requirement for microalgae harvesting.

Equilibrium kinetic and thermodynamic studies of Cr(VI) adsorption onto a novel adsorbent of Eucalyptus camaldulensis waste: Batch and column reactors

Hajira Haroon,Tayyab Ashfaq,Syed Mubashar Hussain Gardazi,Tauqir Ali Sherazi,Muhammad Ali,Naim Rashid,Muhammad Bilal 한국화학공학회 2016 Korean Journal of Chemical Engineering Vol.33 No.10

Cr(VI) adsorption onto Eucalyptus camaldulensis sawdust (ECS) waste was investigated in batch and column reactors. Various parameters, including the adsorbent dose, pH, initial concentration, particle size, contact time and temperature were optimized. The maximum adsorption capacity (35.58mg g−1, 71.16%) was achieved at pH 2.0. Data fitted well to Freundlich and Halsey’s models (R2=0.992), indicating the multilayer adsorption of Cr(VI). It obeys the pseudo-second order kinetics. Endothermic and non-spontaneous nature of Cr(VI) adsorption was observed with positive values of changes in enthalpy (9.83 kJ mol−1), and Gibbs-free energy (1.52, 1.38, 1.24, 1.10 and 0.97 kJmol−1), respectively. In this column study, the breakthrough curve time increased from 670 to 1,270min by increasing the bed height from 5 to 15 cm, respectively. Column data was found well fitted to bed depth service time model. Adsorption capacity at 60% breakthrough was 2,443.636mg L−1. The study indicates that ECS waste can be a promising adsorbent for Cr(VI) remediation from industrial effluents.

Spatio-temporal estimation of basic and effective reproduction number of COVID-19 and post-lockdown transmissibility in Bangladesh

Hridoy Al-Ekram Elahee,Tipo Imrul Hasan,Sami Md. Shamsudduha,Babu Md. Ripon,Ahmed Md. Sayem,Rahman Syed Masiur,Tusher Shekh Md. Shajid Hasan,Rashid Kazi Jihadur,Naim Mohammad 대한공간정보학회 2022 Spatial Information Research Vol.30 No.1

The ongoing COVID-19 pandemic has caused unprecedented public health concern in Bangladesh. This study investigated the role of Non-Pharmaceutical Interventions on COVID-19 transmission and post-lockdown scenarios of 64 administrative districts and the country as a whole based on the spatiotemporal variations of effective reproduction number (Rt) of COVID-19 incidences. The daily confirmed COVID-19 data of Bangladesh and its administrative districts from March 8, 2020, to March 10, 2021, were used to estimate Rt. This study finds that the maximum value of Rt reached 4.15 (3.43, 4.97, 95% CI) in late March 2020, which remained above 1 afterwards in most of the districts. Containment measures are moderately effective in reducing transmission by 24.03%. The Rt was established below 1 from early December 2020 for overall Bangladesh and a gradual increase of Rt above 1 has been seen from early February 2021. The basic reproduction number (R0) in Bangladesh probably varied around 2.02 (1.33–3.28, 95% CI). This study finds a significant positive correlation (r = 0.75) between population density and COVID-19 incidence and explaining 56% variation in Bangladesh. The findings of this study are expected to support the policymakers to adopt appropriate measures for curbing the COVID-19 transmission effectively.

Spatio-temporal estimation of basic and effective reproduction number of COVID-19 and post-lockdown transmissibility in Bangladesh

Hridoy Al-Ekram Elahee,Tipo Imrul Hasan,Sami Md. Shamsudduha,Babu Md. Ripon,Ahmed Md. Sayem,Rahman Syed Masiur,Tusher Shekh Md. Shajid Hasan,Rashid Kazi Jihadur,Naim Mohammad 대한공간정보학회 2022 Spatial Information Research Vol.30 No.2

The ongoing COVID-19 pandemic has caused unprecedented public health concern in Bangladesh. This study investigated the role of Non-Pharmaceutical Interventions on COVID-19 transmission and post-lockdown scenarios of 64 administrative districts and the country as a whole based on the spatiotemporal variations of effective reproduction number (Rt) of COVID-19 incidences. The daily confirmed COVID-19 data of Bangladesh and its administrative districts from March 8, 2020, to March 10, 2021, were used to estimate Rt. This study finds that the maximum value of Rt reached 4.15 (3.43, 4.97, 95% CI) in late March 2020, which remained above 1 afterwards in most of the districts. Containment measures are moderately effective in reducing transmission by 24.03%. The Rt was established below 1 from early December 2020 for overall Bangladesh and a gradual increase of Rt above 1 has been seen from early February 2021. The basic reproduction number (R0) in Bangladesh probably varied around 2.02 (1.33–3.28, 95% CI). This study finds a significant positive correlation (r = 0.75) between population density and COVID-19 incidence and explaining 56% variation in Bangladesh. The findings of this study are expected to support the policymakers to adopt appropriate measures for curbing the COVID-19 transmission effectively.