Digital library

  • Red Algae and Their Use in Papermaking

    Gelidialian red algae, that contain rhizoidal filaments, except the family Gelidiellaceae were processed to make bleached pulps, which can be used as raw materials for papermaking. Red algae consist of rhizoidal filaments, cortical cells usually reddish in color, and medullary cells filled with mucilaginous carbohy- drates. Red algae pulp consists of mostly rhizoidal filaments.

    Red algae pulp of high brightness can be produced by extracting mucilaginous carbohydrates after heating the algae in an aqueous medium and subsequently treating the extracted with bleaching chemicals. In this study, we prepared paper samples from bleached pulps obtained from two red algae species (Gelidium amansii and Gelidium corneum) and compared their properties to those of bleached wood chemical pulps. 

    Author(s): Yung-Bum Seo, Youn-Woo Lee, Chun-Han Lee, Hack-Chul You

  • Recycling nutrients from anaerobic digestates for the cultivation of Phaeodactylum tricornutum: A feasibility study

    The valorisation of Anaerobic digestion waste streams into algal biomass to produce a protein alternative to soybeans could have significant commercial and environmental value. It has the benefit of alleviating the pressure of disposal of nutrient-rich digestate that is rich in nitrogen, phosphorous and trace metals, while potentially reducing the cost of microalgae production. Currently, the use of soybean protein in animal feed has significant negative environmental issues and high carbon footprint associated with its use. This study investigates three types of Anaerobic digestion to grow Phaeodactylum tricornutum Bohlin microalgae. The results found that the crude protein in all concentrations of cow waste and food waste digestates were found to produce a significantly higher concentration of crude protein in comparison to the F/2 control. In addition, cow waste 1% and pig waste 1% formulations were found to have favourable fatty acid profiles, which has significant health benefits in the livestock industry. There was no significant difference in the total fatty acids found in cow waste 1% and pig waste 1% digestates compared to the F/2 control, which was in the range of 243.4 to 269.4 mg/g (dry weight). The other formulations produced a significantly lower (p < .05) concentration of total fatty acids compared to the control. Cow waste 1% was found to be richer in omega-3, eicosapentaenoic acid, compared to pig waste 1%, however, no significant difference was found between the eicosapentaenoic acid, concentration of cow waste 1% and the F/2 control. Overall, in terms of highest total fatty acids and crude protein, cow waste 1% digestate was found to perform the best out of all the digestates tested, and outperformed the F/2 control in terms of crude protein. The P. tricornutum grown in digestate was also found to bioaccumulate higher levels of calcium. P. tricornutum grown in cow waste 1% digestate could offer an alternative viable locally grown protein source for the animal feed industry, with the added advantage of being rich in eicosapentaenoic acid and calcium.

    Author(s): Daniel McDowell, Jaimie TA Dick, Lawrence Eagling, Matthew Julius, Gary N Sheldrake, Katerina Theodoridou, Pamela J Walsh

  • Record Production of Gracilaria Edulis in Culture System in Minicoy Lagoon

    With a view to find out the feasibility of culturing G. Edulis in Minicoy lagoon, experiments Have been started since 1989 and encouraging results were obtained, with a maximum Production value of 7.1 fold increase over the initial seed material introduced in the coir ropes Or nets in 60 days time. From these results it can be Inferred that the grazing of the crop by fishes as reported previously was mainly responsible for the low production values In the earlier Instances. Neverthless grazing has been observed during this year also is some of the ropes, but this particular culture rope which escaped the attack by fish and other organisms has given an idea about the real culture potential of the seaweed G. Edulis in Minicoy Lagoon. Hence this clearly suggests that attempts at preventing grazing of the crop by fishes and other organisms must be taken up in future in seaweed farming to derive maximum benefits.

    Author(s): Chennubhotla, V S Krishnamurthy, Kunhikoya, K K, Anasu Koya, A

  • Recent trends on seaweed fractionation for liquid biofuels production

    Concerns about fossil fuels depletion has led to seek for new sources of energy. The use of marine biomass (seaweed) to produce biofuels presents widely recognized advantages over terrestrial biomasses such as higher production ratio, higher photosynthetic efficiency or carbon-neutral emissions. In here, interesting seaweed sources as a whole or as a residue from seaweed processing industries for biofuel production were identified and their diverse composition and availability compiled. In addition, the pretreatments used for seaweed fractionation were thoroughly revised as this step is pivotal in a seaweed biorefinery for integral biomass valorization and for enabling biomass-to-biofuel economic feasibility processes. Traditional and emerging technologies were revised, with particular emphasis on green technologies, relating pretreatment not only with the type of biomass but also with the final target product(s) and yields. Current hurdles of marine biomass-to-biofuel processes were pinpointed and discussed and future perspectives on the development of these processes given.

    Author(s): Pablo G. del Río, Joana S. Gomes-Dias, Cristina M.R. Rocha, Aloia Romaní, Gil Garrote, Lucília Domingues

  • Recent progress of algae and blue-green algae-assisted synthesis of gold nanoparticles for various applications

    The hazardous effects of current nanoparticle synthesis methods have steered researchers to focus on the development of newer environmentally friendly and green methods for synthesizing nanoparticles using nontoxic chemicals. The development of environmentally friendly methods of nanoparticle synthesis with different sizes and shapes is one of the pressing challenges for the current nanotechnology. Several novel green approaches for the synthesis of AuNPs have been explored using different natural sources, such as plants, algae, bacteria, and fungi. Among organisms, algae and blue–green algae are of particular interest for nanoparticle synthesis. Gold nanoparticles (AuNPs) have a range of applications in medicine, diagnostics, catalysis, and sensors because of their significant key roles in important fields. AuNPs have attracted a significant interest for use in a variety of applications. The widespread use of AuNPs can be accredited to a combination of optical, physical, and chemical properties as well as the miscellany of size, shape, and surface composition that has been adopted through green synthesis methods.

    Author(s): Azhar U. Khan, Masudulla Khan, Nazia Malik, Moo Hwan Cho, Mohammad Mansoob Khan

  • Recent Patterns of Crop Yield Growth and Stagnation

    In the coming decades, continued population growth, rising meat and dairy consumption and expanding biofuel use will dramatically increase the pressure on global agriculture. Even as we face these future burdens, there have been scattered reports of yield stagnation in the world’s major cereal crops, including maize, rice and wheat.

    Here we study data from B2.5 million census observations across the globe extending over the period 1961–2008. We examined the trends in crop yields for four key global crops: maize, rice, wheat and soybeans. Although yields continue to increase in many areas, we find that across 24–39% of maize-, rice-, wheat- and soybean-growing areas, yields either never improve, stagnate or collapse.

    This result underscores the challenge of meeting increasing global agricultural demands. New investments in underperforming regions, as well as strategies to continue increasing yields in the high-performing areas, are required. 

    Author(s): Deepak K. Ray, Navin Ramankutty, Nathaniel D. Mueller, Paul C. West, Jonathan A. Foley

  • Recent Patents on Biofuels from Microalgae

    To reduce greenhouse gas emissions and to prevent their devastative impacts of human health and the environment, bioenergy carriers have been at center of attention to supply global energy demand. Microalgae as solar energy-driven factories could efficiently convert carbon dioxide to a variety of hydrocarbons that can be used as biofuels. With the aim of realizing the current status of algal biofuels, respective patents were surveyed in this chapter using various databases, i.e., World Intellectual Property Organization, United States Patent and Trademark Office, and European Patent Office database. Information derived from the aforementioned databases was categorized into three: upstream, mainstream, and downstream strategies. The upstream strategies included patents on selection of algal strain and genetic engineering approaches while the main- stream strategies reviewed and discussed innovations pertaining to improving algal cultivation systems, production media and nutrients supply, and CO2 supply. Finally, in the downstream strategies section, the inventions aimed at enhancing harvesting and dewatering of microalgae cells and lipid extraction were presented.

    Author(s): Ahmad Farhad Talebi, Meisam Tabatabaei, Mortaza Aghbashlo

  • Recent developments on biofuels production from microalgae and macroalgae

    Biofuels from algae are considered as promising alternatives of conventional fossil fuels, as they can eliminate most of the environmental problems. The present study focuses on all the possible avenues of biofuels production through biochemical and thermochemical conversion methods in one place, bringing together both microalgae and macroalgae on the same platform. It provides a brief overview on the mechanism of different biofuel production from algae. Factors affecting the biofuel process and the associated challenges have been highlighted alongwith analysis of techno-economic study available in literature. Undoubtly, biodiesel is the center of attraction among other biofuels. However, their routes and process need to be optimized in order to bring the minimum fuel selling price (MFSP) of biodiesel competitive. Technological challenges have not been overcome to make biofuel production process energetically and commercially viable. Macroalgae are low in lipid content. Therefore, the use of macroalgae is restricted for gaseous fuels or fermentative methods of liquid biofuels production. Anaerobic digestion of algal biomass is easy and seems promising as the process is simple in terms of engineering and infrastructure requirement. Hydrogen production by microalgae through biophotolysis seems interesting as it directly converts the solar energy into hydrogen. However, the process has not been scaled-up till today. Hydrothermal liquefaction (HTL) is more promising due to handling of wet biomass at moderate temperature and pressure and conversion of whole biomass into high quality oil. However, HTL process is energy intensive.

    Author(s): Kanhaiya Kumar, Supratim Ghosh, Irini Angelidaki, Susan L. Holdt, Dimitar B. Karakashev, Merlin Alvarado Morales, Debabrata Das

  • Recent advances in thermochemical methods for the conversion of algal biomass to energy

    Thermochemical techniques are being operated for the complete conversion of diverse biomasses to biofuels. Among the feedstocks used for thermochemical processes, algae are the promising biomass sources owing to their advantages over other feedstocks such as biomass productivity, renewability and sustainability. Due to several advantages, algal biomass is considered as a source for third generation biofuel. This review work aims to provide a state-of-the-art on the most commonly used thermochemical methods namely torrefaction, pyrolysis, and gasification processes. Furthermore, the production of biofuels from algal biomass was comprehensively articulated. Different algal strains used in thermochemical techniques and their conditions of operation were compared and discussed. The yield and quality of solid (char), liquid (bio-oil) and gaseous (syngas) products obtained through thermochemical methods were reviewed and analysed to understand the efficacy of each technique. End product percentage, quality and advantages of the torrefaction, pyrolysis, and gasification were summarized. It is found that the biofuel produced from the torrefaction process was easy to store and deliver and had higher utilization efficiency. Among the existing thermochemical methods, the pyrolysis process was widely used for the complete conversion of algal biomass to bio-oil or char. This study also revealed that the gasification (supercritical) method was the most energy efficient process for conversion of wet algal biomass. The reactor used in the thermochemical process and its subprocess was also highlighted. This study revealed that the fixed bed reactor was suitable for small scale production whereas the fluidized bed reactor could be scaled up for industrial production. In addition to that environmental impacts of the products were also spotlighted. Finally, the perspectives and challenges of algal biomass to bioenergy conversion were addressed.

    Author(s): Pritam Das, Chandramohan V.P., Thangavel Mathimani, Arivalagan Pugazhendhi

  • Recent advances in the understanding of the biological basis for Gigartina skottsbergii (Rhodophyta) cultivation in Chile

    The demand in Chile for carrageenophytic algae has increased strongly during the last 3 years, with emphasis on Gigartina skottsbergii, a species representing landings of 32 438 t (wet) during 1996. Various sources of information indicate that this species is being over-exploited and therefore the development of cultivation technologies is needed to support the local carrageenan industry. In this study we summarize currently available information on laboratory, outdoor tank and open sea culture of G. skottsbergii. The results indicate that viable spores of G. skottsbergii can be obtained, mainly during winter, with germination rates of both tetraspores and carpospores, up to 40%. Germlings of G. skottsbergii were succesfully transplanted from the laboratory to outdoor tanks, where they displayed survival values higher than 80% during spring. Experimental trials in the field indicate that G. skottsbergii can be cultivated on rope systems, with tissue fragments used as inoculum. This last result suggests that regeneration from fragments is an alternative method for propagation and massive cultivation of G. skottsbergii in Chile.

    Author(s): Renato Westermeier, Juan A. Correa, Alejandro H. Buschmann

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