Three Microalgae Strains Culture Using Human Urine and Light (original) (raw)
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Microalgae as second generation biofuel. A review
Agronomy for Sustainable Development, 2000
Microalgae are autotrophic microorganisms having extremely high photosynthetic efficiency and are valued as rich source of lipids, hydrocarbons, and other complex oils for biodiesel besides being an invaluable source of bioethanol, biomethane, and biohydrogen. Biodiesel produced from oilseed crops such as jatropha and soy have lower yields per unit land area and threaten food security. Indeed, microalgae have higher oil yields amounting to about 40 times more oil per unit area of land in comparison to terrestrial oilseed crops such as soy and canola. Further, microalgae production does not require arable land for cultivation. Biofuel is regarded as a proven clean energy source and several entrepreneurs are attempting to commercialize this renewable source. Technology for producing and using biofuel has been known for several years and is frequently modified and upgraded. In view of this, a review is presented on microalgae as second generation biofuel. Microalgal farming for biomass production is the biggest challenge and opportunity for the biofuel industry. These are considered to be more efficient in converting solar energy into chemical energy and are amongst the most efficient photosynthetic plants on earth. Microalgae have simple cellular structure, a lipid-rich composition, and a rapid rate of reproduction. Many microalgal strains can be grown in saltwater and other harsh conditions. Some autotrophic microalgae can also be converted to heterotrophic ones to accumulate high quality oils using organic carbon. However, there are several technical challenges that need to be addressed to make microalgal biofuel profitable. The efficiency of microalgal biomass production is highly influenced by environmental conditions, e.g., light of proper intensity and wavelength, temperature, CO2 concentration, nutrient composition, salinities and mixing conditions, and by the choice of cultivation systems: open versus closed pond systems, photobioreactors. Currently, microalgae for commercial purpose are grown mostly in open circular/elongated “raceway” ponds which generally have low yields and high production costs. However, a hybrid system combining closed photobioreactor and open pond is a better option. The biggest hurdle in commercialization of microalgal biofuel is the high cost and energy requirement for the microalgal biomass production, particularly agitation, harvesting, and drying of biomass. In order to conserve energy and reduce costs, algae are often harvested in a two-step process involving flocculation followed by centrifugation, filtration, or micro-straining to get a solid concentration. However, the major bottlenecks in algal biodiesel production within the cell can be identified and handled by adopting a system approach involving transcriptomics, proteomics, and metabolomics. Research and developments in the field of new materials and advanced designs for cultivation in closed bioreactors, use of waste water for biomass production, screening of efficient strains, high-value coproduct strategy, and cutting-edge metabolic engineering are thought to provide the biggest opportunities to substantially improve the cost effectiveness of such production systems.
Cultivating Microalgae in Domestic Wastewater for Biodiesel Production
Notulae Scientia Biologicae, 2012
The objective of this study was to evaluate the growth of nine species of microalgae (green and blue green microalgae) on domestic wastewater obtained from Zenein Wastewater Treatment Plant (ZWWTP), Giza governorate, Egypt. The species were cultivated in different wastewater treatments namely: without treatment; after sterilization; with nutrients with sterilization and with nutrients without sterilization. The experiment was conducted in triplicate and cultures were incubated at 25±1°C under continuous shaking (150 rpm) and illumination (2000 Lux) for 15 days. Algal growth parameters i.e., pH, electric conductivity (EC), optical density (OD), dry weight (DW) and chlorophyll-a (Ch-a) were measured at zero-time and at the end of the experimental period; while, the percentages of total lipids, biodiesel and the residual sediments (glycerine, pigments, etc) were determined in the harvested algal biomass. The data revealed that domestic wastewater with nutrients and with sterilization (T 3) was promising for cultivating five algal species as compared to the synthetic media. Moreover, the sterilized-domestic wastewater (T 2) was the selective medium for cultivating Oscillatoria sp. and Phormedium sp; however, T 1 medium (wastewater without treatment) was the promising medium for cultivating Nostoc humifusum. Biodiesel production from the algal species cultivated in synthetic media was ranging between 3.90% (Wollea saccata) and 12.52% (Nostoc muscorum). On the other hand, the highest biodiesel production from algal biomass cultivated in wastewater was obtained by Nostoc humifusum (11.80%) when cultivated in wastewater without treatment (T 1) and the lowest (3.80%) was recorded by Oscillatoria sp. when cultivated on the sterilized-domestic wastewater (T 2). The results of this study suggest that cultivating microalgae on domestic wastewater combines nutrients removal and algal lipid production for potential use as a biodiesel feedstock. Additionally, using the domestic wastewater, as nutrient media for microalgae cultivation, is suitable and non-expensive method as compared to the conventional cultivation methods for sustainable biodiesel and glycerol production.
Critical Reviews in Biotechnology, 2019
Microalgae have been exploited for biofuel generation in the current era due to its enormous energy content, fast cellular growth rate, inexpensive culture approaches, accumulation of inorganic compounds, and CO2 sequestration. Currently, research is ongoing towards the advancement of the microalgae cultivation parameters to enhance the biomass yield. The main objective of this study was to delineate the progress of physicochemical parameters for microalgae cultivation such as gaseous transfer, mixing, light demand, temperature, pH, nutrients and the culture period. This review demonstrates the latest research trends on mass transfer coefficient of different microalgae culturing reactors, gas velocity optimization, light intensity, retention time, and radiance effects on microalgae cellular growth, temperature impact on chlorophyll production, and nutrient dosage ratios for cellulosic metabolism to avoid nutrient deprivation. Besides that, cultivation approaches for microalgae associated with mathematical modeling for different parameters, mechanisms of microalgal growth rate and doubling time have been elaborately described. Along with that, this review also documents potential lipid-carbohydrate-protein enriched microalgae candidates for biofuel, biomass productivity, and different cultivation conditions including open-pond cultivation, closed-loop cultivation, and photobioreactors. Various photobioreactor types, the microalgae strain, productivity, advantages, and limitations were tabulated. In line with microalgae cultivation, this study also outlines in detail numerous biofuels from microalgae.
The feasibility of biodiesel production by microalgae using industrial wastewater
Bioresource Technology, 2012
This study investigated nitrogen and phosphorus assimilation and lipid production of microalgae in industrial wastewater. Two native strains of freshwater microalgae were evaluated their biomass growth and lipid production in modified BBM medium. Chlamydomonas sp. TAI-2 had better biomass growth and higher lipid production than Desmodesmus sp.TAI-1. The optimal growth and lipid accumulation of Chlamydomonas sp. TAI-2 were tested under different nitrogen sources, nitrogen and CO 2 concentrations and illumination period in modified BBM medium. The optimal CO 2 aeration was 5% for Chlamydomonas sp. TAI-2 to achieve maximal lipid accumulation under continuous illumination. Using industrial wastewater as the medium, Chlamydomonas sp. TAI-2 could remove 100% NH 4 + -N (38.4 mg/L) and NO 3 À -N (3.1 mg/L) and 33% PO 4 3À -P (44.7 mg/L) and accumulate the lipid up to 18.4%. Over 90% of total fatty acids were 14:0, 16:0, 16:1, 18:1, and 18:3 fatty acids, which could be utilized for biodiesel production.
Evaluation of the potential for some isolated microalgae to produce biodiesel
Egyptian Journal of Petroleum, 2015
The energy and the world food crises have ignited interest in algal culture for making biodiesel, bioethanol, biobutanol and other biofuels using the land that is not suitable for agriculture. Algal fuel is an alternative to fossil fuel that uses algae as its source of natural deposits. Microalgal lipids are the oils of the future for sustainable biodiesel production. One of the most important roles in obtaining oil from microalgae is the choice of species. A total of fifteen microalgal isolates, obtained from brackish and fresh waters, were assayed at the laboratory for their ability to high biomass productivity and lipid content. Only three microalgae were selected as the most potent isolates for biomass and lipid production. They have been identified as Chlorella vulgaris, Scenedesmus quadri and Trachelomonas oblonga. All of them were cultivated on BG11 media and harvested by centrifugation. The dry weight of the three isolates was recorded as 1.23, 1.09 and 0.9 g/l while the lipid contents were 37%, 34% and 29%, respectively which can be considered a promising biomass production and lipid content.
Biodiesel from microalgae: A critical evaluation from laboratory to large scale production
The economically significant production of carbon-neutral biodiesel from microalgae has been hailed as the ultimate alternative to depleting resources of petro-diesel due to its high cellular concentration of lipids, resources and economic sustainability and overall potential advantages over other sources of biofuels. Pertinent questions however need to be answered on the commercial viability of large scale production of biodiesel from microalgae. Vital steps need to be critically analysed at each stage. Isolation of microalgae should be based on the question of whether marine or freshwater microalgae, cultures from collections or indigenous wild types are best suited for large scale production. Furthermore, the determination of initial sampling points play a pivotal role in the determination of strain selection as well as strain viability. The screening process should identify, purify and select lipid producing strains. Are natural strains or stressed strains higher in lipid productivity? The synergistic interactions that occur naturally between algae and other microorganisms cannot be ignored. A lot of literature is available on the downstream processing of microalgae but a few reports are available on the upstream processing of microalgae for biomass and lipid production for biodiesel production. We present in this review an empirical and critical analysis on the potential of translating research findings from laboratory scale trials to full scale application. The move from laboratory to large scale microalgal cultivation requires careful planning. It is imperative to do extensive pre-pilot demonstration trials and formulate a suitable trajectory for possible data extrapolation for large scale experimental designs. The pros and cons of the two widely used methods for growing microalgae by photobioreactors or open raceway ponds are discussed in detail. In addition, current methods for biomass harvesting and lipid extraction are critically evaluated. This would be novel approach to economical biodiesel production from microalgae in the near future. Globally, microalgae are largest biomass producers having higher neutral lipid content outcompeting terrestrial plants for biofuel production. However, the viscosities of microalgal oils are usually higher than that of petroleum diesel.
Microalgae are sunlight-driven miniature factories that convert atmospheric CO 2 to polar and neutral lipids which after esterification can be utilized as an alternative source of petroleum. Further, other metabolic products such as bioethanol and biohydrogen produced by algal cells are also being considered for the same purpose. Microaglae are more efficient than the conventional oleaginous plants in capturing solar energy as they have simpler cellular organization and high capacity to produce lipids even under nutritionally challenged and high salt concentrations. Commercially, microalgae are cultivated either in open pond systems or in closed photobioreactors. The photobioreactor systems including tubular bioreactors, plate reactors and bubble column reactors have their own advantages as they provide sterile conditions for growing algal biomass. Besides, other culture conditions such as light intensity, CO 2 concentration, nutritional balance, etc, in closed reactors remain controlled. On the other hand, though the open ponds provide a cost-effective option to utilize natural light facility for algal cells, the tough maintenance of optimal and stable growth conditions makes it difficult to manage the economy of the process. Further, these systems are much more susceptible to contamination with unwanted microalgae and fungi, bacteria and protozoa that feed on algae. Recently, some work has been done to improve lipid production from algal biomass by implementing in silico and in vitro biochemical, genetic and metabolic engineering approaches. This article represents a comprehensive discussion about the potential of microalgae for the production of valuable lipid compounds that can be further used for biodiesel production.
2020
The main purpose of this review is to evaluate the design of several photobioreactor (PBR) systems with the microalgae cultures and the quality of the microalgae species related to the production of lipid for biodiesel. In general, microalgae cultivation is divided into two systems: open pond system (unstirred, circular, raceway) and closed system (flat-panel, horizontal tube, helical tube, vertical tube, stirred tank, big bag), made by transparent and waterproof materials, and able to provide an ideal cultivation environment for photosynthetic microalgae. There are some issues to be considered in microalgae cultivation systems such as modelling by simulation, data collecting, mixing, illumination, gas exchange, availability of the nutritions and the cost of the system. Most common microalgae for PBRs and their lipid percentages as follows: Chlorella ellipsoidea %84, Schizochytrium sp . %77, Botryococcus braunii %74, Nitzschia sp. %51 Chlorella protothecoides %51 and Neochloris oleo...
Microalgae Cultivation Using Various Sources of Organic Substrate for High Lipid Content
New Trends in Urban Drainage Modelling. UDM 2018. Green Energy and Technology, 2018
The ingredients of photosynthetic reactions can be exploited to increase algal culture productivity to effectively treat wastewater by significantly reducing the presence of organic and inorganic compounds. In this study, we introduced microalgae Chlorella pyrenoidosa (C. pyrenoidosa) into four different wastewater samples, including Palm Oil Mill Effluent (POME), piggery, domestic, and mixed-kitchen wastes. The C. pyrenoidosa growth efficacy of POME and subsequent drop in nutrients were demonstrated. It was clearly seen that POME had the highest Chemical Oxygen Demand (COD) values at 700 mg L −1. The Total Nitrogen (TN) ratio for the piggery sample was the highest at 590 mg L −1. Productivity was evaluated in terms of chlorophyll content, growth rate, biomass, and lipid content. POME and domestic wastes had the first and second highest chlorophyll a content of 3 mg L −1 and 2.5 mg L −1 , respectively. The optimum growth rate for C. pyrenoidosa was observed when using POME as a substrate. This study confirmed that Cell Dry Weight (CDW) in POME was the highest with 500 mg L −1 after 20 days cultivation of C. pyrenoidosa, when compared to other substrates. Maximum lipid content was recorded for POME, domestic sample, piggery, and mixed-kitchen waste, at 182, 148, 0.99, and 117 mg L −1 , respectively. The above results revealed that POME was the best substrate choice for alga
Green Chemistry, 2011
Microalgae are being considered as a viable feedstock for large-scale production of biodiesel. However, though it may look simpler to obtain lipids from microalgae, the overall process of choosing an algal strain, cultivation, harvesting, dewatering, and extraction of oil is quite complicated and not economically prudent at this time. A thorough understanding of algae and the overall biodiesel production process discussed in this paper is vital so that focused research might lower the costs involved. Various diverse species of microalgae are currently being used as feedstocks for biofuel. Heterotrophic culture may be preferred over photoautotrophic cultivation. For cultivation, specially fabricated photobioreactors (PBRs) have the capability to overcome the constraints and limitations of the open raceway ponds, although the former are cost intensive as compared to the latter. Exergy analysis of algal-biodiesel-carbon dioxide cycle shows the overall process to be renewable and hence should attain global attention.