A Simulation Analysis of a Microalgal-Production Plant for the Transformation of Inland-Fisheries Wastewater in Sustainable Feed

The present research evaluates the simulation of a system for transforming inland-fisheries wastewater into sustainable fish feed using Designer® software. The data required were obtained from the experimental cultivation of Chlorella sp. in wastewater supplemented with N and P. According to the results, it is possible to produce up to 11,875 kg/year (31.3 kg/d) with a production cost of up to 18 (USD/kg) for dry biomass and 0.19 (USD/bottle) for concentrated biomass. Similarly, it was possible to establish the kinetics of growth of substrate-dependent biomass with a maximum production of 1.25 g/L after 15 days and 98% removal of available N coupled with 20% of P. It is essential to note the final production efficiency may vary depending on uncontrollable variables such as climate and quality of wastewater, among others.

Analisis Kandungan Fitokimia dan Aktivitas Antioksidan Mikroalga Chlorella sp. Berdasarkan Variasi Waktu Pencahayaan

Mikroalga mengandung metabolit sekunder yang potensial untuk dikembangkan. Metabolit sekunder digunakan untuk pertahanan kimia terhadap predator di lingkungan air. Salah satu jenis mikroalga yang dapat dikembangkan metabolit sekundernya adalah Chlorella sp. Kondisi lingkungan saat kultivasi Chlorella sp. mempengaruhi jumlah sel, kandungan metabolit sekunder dan kestabilan senyawa antioksidan mikroalga. Faktor lingkungan yang menjadi fokus penelitian adalah faktor cahaya. Penelitian ini bertujuan untuk menganalisis kandungan fitokimia dan antioksidan biomassa mikroalga Chlorella sp. dengan variasi waktu pencahayaan. Variasi pemberian cahaya pada proses kultivasi menggunakan periode terang : gelap yang terbagi menjadi 2 kelompok yaitu 12:12 (terang:gelap) jam dan 18:6 (terang:gelap) jam. Metode yang digunakan untuk analisis kandungan fitokimia menggunakan metode Harborne dan analisis aktivitas antioksidan menggunakan metode DPPH (1,1-diphenyl-2-picrylhydrazyl). Hasil penelitian menunjukkan bahwa ekstrak mikroalga Chlorella sp. dengan variasi waktu pencahayaan (terang:gelap) 12:12 jam mengandung alkaloid, flavonoid, saponin, steroid, kuinon dan terpenoid. Sedangkan, ekstrak mikroalga Chlorella sp. dengan variasi waktu pencahayaan (terang:gelap) 18:6 jam mengandung alkaloid, flavonoid, saponin dan terpenoid. Hasil aktivitas antioksidan ekstrak mikroalga Chlorella sp. dengan variasi waktu pencahayaan (terang:gelap) 12:12 jam IC50 sebesar 40,421 dan ekstrak Chlorella sp. dengan variasi waktu pencahayaan (terang:gelap) 18:6 jam memiliki IC50 sebesar 8,992. Berdasarkan penelitian diperoleh bahwa ekstrak mikroalga yang diberi waktu pencahayaan tinggi menghasilkan aktivitas antioksidan yang lebih kuat dibandingkan pencahayaan rendah.

Optimization of Chlorella Culture Conditions with Response Surface Methodology to Increase Biomass

Microalgae is gaining popularity as a major ingredient in nutrition supplements. To mass cultivate, it is imperative to improve the biomass yield hence optimization of cultures conditions becomes paramount. In this work, an attempt has been made to optimize the microalgal production using response surface methodology (RSM) and validate further the optimized parameters. The optimum conditions for the cultivation of Chlorella sp. KPU016 under optimized nutrient conditions were pH 8.2, the light intensity of 3100 lx, glycerol 1.44 g.L-1 (under pre-set conditions of 12 h lighting, the temperature at 27±1°C. With these RSM-driven optimum conditions, the yield of microalgal biomass achieved was 282.50 mg.L-1. For larger-scale microalgal harvesting, the validated optimal conditions can be inferred as the best for enhanced microalgal production. The isolate was partially sequenced and submitted to the NCBI database and the GenBank accession number is MZ348364.

Optimization of the Growth and Performance of Several Cynobacteria Species in a Pilot Scale Raceway Pond for CO2 Bio-Sequestration

Due to the limited availability of fresh water and the high cost of land for plant culture, microalgae cultivation has attracted significant attention in recent years and has been shown to be the best option for CO2 bio-sequestration. Bio-sequestration of CO2 through algae bioreactors has been hailed as one of the most promising and ecologically benign methods available. This research study was taken up to alleviate certain limitations associated with the technology such as low CO2 sequestration efficiency and low biomass yields. In this study three distinct cyanobacterial strains, Chlorella sp., Synechococcus sp., and Spirulina sp., were tested in 10 litre raceway ponds for their capacity for CO2 bioconversion and high biomass production under various CO2 concentrations at different EC. The highest growth rate of all tested cyanobacterial strains was observed during the first 4 days of cultivation under CO2 5% to 10%. Additionally, all these cyanobacterial strains were explored for their bioremediation capabilities. The results showed that the Chlorella sp., Synechococcus sp., and Spirulina sp. were able to remove COD of the wastewater by 56%, 48% and 77% respectively and the BOD removal efficiency was 48%, 30% and 52% respectively. The primary results indicated that the Spirulina sp. was to be the best cynobacteria studied in terms of biomass production, CO2 bioconversion, and bioremediation capacities. Therefore, the Spirulina sp. was further scaled up in 1500 litre raceway pond for CO2 bio-sequestration and biomass production. The biomass collected was utilised to extract biomolecules such as protein, carbohydrate and lipids.

Cultivation and Biorefinery of Microalgae (Chlorella sp.) for Producing Biofuels and Other Byproducts: A Review

Microalgae-based carbon dioxide (CO2) biofixation and biorefinery are the most efficient methods of biological CO2 reduction and reutilization. The diversification and high-value byproducts of microalgal biomass, known as microalgae-based biorefinery, are considered the most promising platforms for the sustainable development of energy and the environment, in addition to the improvement and integration of microalgal cultivation, scale-up, harvest, and extraction technologies. In this review, the factors influencing CO2 biofixation by microalgae, including microalgal strains, flue gas, wastewater, light, pH, temperature, and microalgae cultivation systems are summarized. Moreover, the biorefinery of Chlorella biomass for producing biofuels and its byproducts, such as fine chemicals, feed additives, and high-value products, are also discussed. The technical and economic assessments (TEAs) and life cycle assessments (LCAs) are introduced to evaluate the sustainability of microalgae CO2 fixation technology. This review provides detailed insights on the adjusted factors of microalgal cultivation to establish sustainable biological CO2 fixation technology, and the diversified applications of microalgal biomass in biorefinery. The economic and environmental sustainability, and the limitations and needs of microalgal CO2 fixation, are discussed. Finally, future research directions are provided for CO2 reduction by microalgae.