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Enriched sewage sludge from anaerobic pre-treatment in spurring valorization potential of black soldier fly larvae
(2022-09-01)
Raksasat, Ratchaprapa
;
Abdelfattah, Eman Alaaeldin
;
Liew, Chin Seng
;
Rawindran, Hemamalini
;
Kiatkittipong, Kunlanan
The valorization of sewage sludge by black soldier fly larvae (BSFL) has gained attentions for sewage sludge management since the sludge can be reduced securely as well as larval biomass can be used for biorefineries application. Nevertheless, the BSFL growth was impeded while assimilating nutrition from sewage sludge due to the presence of extracellular polymeric substances (EPS) that had entrapped the essential nutrients inside. Accordingly, the pre-treatment of sewage sludge via anaerobic digestion at different pH was employed in this work to rupture the EPS structure and release more nutrients for larval growth. The results showed that larvae fed with raw sewage sludge had attained the lowest final larval weight (2.05 ± 0.38 mg/larva) as opposed to batches fed with pre-treated sewage sludges. This was because the soluble carbohydrate (more than 6.81 ± 1.31 mg of glucose/g sewage sludge) in EPS was released after anaerobic pre-treatment, facilitating larval assimilation for growth. Furthermore, it was observed that further increasing of pH for sewage sludge pre-treatment had led to lower final larval weight gained due to the inhibitory effect stemming from ammonia production at higher pH. The anaerobic pre-treatment of sewage sludge being executed at pH 3 for 8 days had achieved the highest final larval weight at 7.34 ± 0.97 mg/larva. The still low quality of sewage sludges after the pre-treatment also offered benefit, where high sewage sludge reduction and waste reduction index were recorded due to the necessity of BSFL to consume more sewage sludge in compensating the nutrients destitution in sludge. Lastly, the possibility of predicting final larval weight was successfully materialized via a statistical model derived from the multiple linear regression method. The derived model incorporated the interactive parameters of anaerobic pre-treated pH and durations at various combinations could predict the final larval weight.
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Hydrocarbon production and biodiesel properties of a green microalga Botryococcus braunii KMITL 2 cultivated outdoor in open pond and closed photobioreactor
(2018-03-01)
Ruangsomboon, Suneerat
Botryococcus braunii is a promising feedstock for biodiesel production. In general, selection of the most suitable cultivation systems is based on profitable yield and oil quality. The feasibility of using this alga as feedstock for commercial biodiesel production was tested by comparing the cultivation in open pond and closed photobioreactor under the 5 g⋅kg-1 optimum salinity condition previously found, and the results were that the hydrocarbon content (40.7±1.6%) of the alga cultivated in open pond was higher than that cultivated in the photobioreactor and its biomass (2.9±0.1 g⋅L-1) was much higher; its biodiesel properties, however, were nearly identical with cetane values of 48.15-56.99. Drastically different though were the hydrocarbon yields-cultivation in the open pond produced 2.3 times higher yield than the closed photobioreactor. Hence, outdoor cultivation under optimum salinity in open pond was considered suitable for biodiesel production by this algal strain.
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Enhanced hydrocarbon production and improved biodiesel qualities of Botryococcus braunii KMITL 5 by vitamins thiamine, biotin and cobalamin supplementation
(2018-01-01)
Ruangsomboon, Suneerat
;
Sornchai, Piyanuch
;
Prachom, Noratat
Botryococcus braunii, a green microalga which is a potentially good biodiesel feedstock, was isolated from a freshwater fish pond in Bangkok, and the effects of B-vitamins—thiamine, biotin and cobalamin as well as their mixes—on its biomass, hydrocarbon production, carbohydrate content and biodiesel properties were investigated, using a control group that was not supplemented with any vitamins. The addition of thiamine increased the alga's biomass and hydrocarbon content, whereas addition of biotin, cobalamin and mixes of all three vitamins did not increase its hydrocarbon content. Among the vitamins tested, thiamine 150 μg L− 1 was the best for producing high biomass (2.08 ± 0.07 g L− 1), hydrocarbon content (37.29 ± 0.41%), hydrocarbon yield (0.77 ± 0.03 g L− 1) and hydrocarbon productivity (90.32 ± 3.05 mg L− 1 d− 1). Maximum carbohydrate content (386 ± 39 mg g− 1) was achieved by addition of 1 μg L− 1 cobalamin. Compared to the control group, the alga cultured in media supplemented with 100 μg L− 1 thiamine showed better biodiesel properties with lower iodine value (76.42 g I<inf>2</inf> 100 g− 1), cold filter plugging point (9.90 °C) and higher cetane number (54.30). Therefore, thiamine was shown to be a promising culture medium supplement for this strain for using it as a feedstock for biodiesel production. An investigation of vitamin B-related gene in B. braunii KMITL 5 found related genes for thiamine (thi), biotin (bioB and bioF) and cobalamin (metE and metH) vitamins, which are marks of vitamin autotrophy in algae.
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Enthalpy relaxation in sucrose-maltodextrin-sodium citrate bioglass
(2017-10-01)
Sritham, Eakasit
;
Gunasekaran, Sundaram
Glass transition characteristics of sucrose (SC)-maltodextrin (MD)-sodium citrate (NaCit) bioglass system were investigated using differential scanning calorimetry. Samples were formulated with different SC:MD (7:3, 5:5 and 3:7 by mass) and NaCit/SC (0, 0.1 and 0.2 by mole) ratios, and were equilibrated to residual moisture contents of 0.27–0.35 %wb. Isothermal aging experiments were conducted with the degree of undercooling from 12 to 57 °C and aging times of 8, 20, 47 and 71 h. In general, the Kohlrausch-Williams-Watts (KWW) decay function fit well with the experimental enthalpy relaxation data. The enthalpy relaxation time (τKWW) and the time required for 50% completion of theoretical possible maximum enthalpy relaxation at constant temperature (t<inf>ϕ(t)=0.5</inf>) increased with increasing MD content; lowering the aging temperature had similar effects on τKWW and t<inf>ϕ(t)=0.5</inf>. In the system with high SC and NaCit concentrations (SC:MD = 7:3 and NaCit/SC = 0.2), a substantial increase in τKWW and t<inf>ϕ(t)=0.5</inf> were observed when aging temperature <inf>decreased slightly;</inf> these systems also exhibited the greatest apparent activation energy. The findings reveal that NaCit can enhance the stability of low-moisture bioglass by primarily interacting with SC and form large less-mobile clusters, which helps to improve glass transition temperature and restrict the matrix mobility.
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Enhanced growth and hydrocarbon production of Botryococcus braunii KMITL 2 by optimum carbon dioxide concentration and concentration-dependent effects on its biochemical composition and biodiesel properties
(2017-01-01)
Ruangsomboon, Suneerat
;
Prachom, Noratat
;
Sornchai, Piyanast
The purposes of this study were to find the optimum level of supplementing CO<inf>2</inf> for increasing the biomass and hydrocarbon production of B. braunii KMITL 2 (A race) and to determine the effects of CO<inf>2</inf> level on CO<inf>2</inf> fixation and biodiesel properties. The experimental results showed that the alga supplemented with 10% CO<inf>2</inf> produced the highest biomass (1.48 ± 0.02 g L−1) and CO<inf>2</inf> fixation rate (100.43 ± 1.42 mg L−1 d−1) that were 2.7 and 5.3 times higher than the control (0.04% CO<inf>2</inf>). The gravimetric hydrocarbon content (36.82 ± 3.39%) and hydrocarbon titer (0.35 ± 0.03 g L−1) of the alga supplemented with 5% CO<inf>2</inf> were 1.6 and 2.7 times higher than the control. Cultivation of this strain under 5% CO<inf>2</inf> gave the highest hydrocarbon yield and good biodiesel properties with the lowest iodine value and a higher CN value than the ASTM D6751 and EN 14214 fuel standards.

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