title: Aquatic plant Azolla as the universal feedstock for biofuel production.
abstract: BACKGROUND
  The quest for sustainable production of renewable and cheap biofuels has triggered an intensive search for domestication of the next generation of bioenergy crops. Aquatic plants which can rapidly colonize wetlands are attracting attention because of their ability to grow in wastewaters and produce large amounts of biomass. Representatives of Azolla species are some of the fastest growing plants, producing substantial biomass when growing in contaminated water and natural ecosystems. Together with their evolutional symbiont, the cyanobacteriumAnabaena azollae,Azolla biomass has a unique chemical composition accumulating in each leaf including three major types of bioenergy molecules: cellulose/hemicellulose, starch and lipids, resembling combinations of terrestrial bioenergy crops and microalgae.
  
  
  RESULTS
  The growth ofAzolla filiculoidesin synthetic wastewater led up to 25, 69, 24 and 40 % reduction of NH4-N, NO3-N, PO4-P and selenium, respectively, after 5 days of treatment. This led to a 2.6-fold reduction in toxicity of the treated wastewater to shrimps, common inhabitants of wetlands. Two Azolla species,Azolla filiculoidesandAzolla pinnata,were used as feedstock for the production of a range of functional hydrocarbons through hydrothermal liquefaction, bio-hydrogen and bio-ethanol. Given the high annual productivity of Azolla, hydrothermal liquefaction can lead to the theoretical production of 20.2 t/ha-year of bio-oil and 48 t/ha-year of bio-char. The ethanol production fromAzolla filiculoides,11.7 × 103L/ha-year, is close to that from corn stover (13.3 × 103L/ha-year), but higher than from miscanthus (2.3 × 103L/ha-year) and woody plants, such as willow (0.3 × 103L/ha-year) and poplar (1.3 × 103L/ha-year). With a high C/N ratio, fermentation of Azolla biomass generates 2.2 mol/mol glucose/xylose of hydrogen, making this species a competitive feedstock for hydrogen production compared with other bioenergy crops.
  
  
  CONCLUSIONS
  The high productivity, the ability to grow on wastewaters and unique chemical composition make Azolla species the most attractive, sustainable and universal feedstock for low cost, low energy demanding, near zero maintenance system for the production of a wide spectrum of renewable biofuels.
authors: School of Sciences, RMIT University, Bundoora, VIC Australia.
authors: Ana F
authors: AF
authors: Miranda
authors: Thermo-Catalytic Processes Area (TPA), Bio-Fuels Division (BFD), CSIR-Indian Institute of Petroleum, Dehradun, Uttarakhand 248005 India.
authors: Bijoy
authors: B
authors: Biswas
authors: The Energy and Resources Institute, New Delhi, 110 003 India.
authors: Narasimhan
authors: N
authors: Ramkumar
authors: Thermo-Catalytic Processes Area (TPA), Bio-Fuels Division (BFD), CSIR-Indian Institute of Petroleum, Dehradun, Uttarakhand 248005 India.
authors: Rawel
authors: R
authors: Singh
authors: Thermo-Catalytic Processes Area (TPA), Bio-Fuels Division (BFD), CSIR-Indian Institute of Petroleum, Dehradun, Uttarakhand 248005 India.
authors: Jitendra
authors: J
authors: Kumar
authors: School of Architecture and Design, RMIT University, Melbourne, Australia.
authors: Anton
authors: A
authors: James
authors: School of Engineering, RMIT University, Melbourne, Australia.
authors: Felicity
authors: F
authors: Roddick
authors: The Energy and Resources Institute, New Delhi, 110 003 India.
authors: Banwari
authors: B
authors: Lal
authors: The Energy and Resources Institute, New Delhi, 110 003 India.
authors: Sanjukta
authors: S
authors: Subudhi
authors: Thermo-Catalytic Processes Area (TPA), Bio-Fuels Division (BFD), CSIR-Indian Institute of Petroleum, Dehradun, Uttarakhand 248005 India.
authors: Thallada
authors: T
authors: Bhaskar
authors: School of Sciences, RMIT University, Bundoora, VIC Australia.
authors: Aidyn
authors: A
authors: Mouradov
keywords: Azolla; Bio-ethanol; Bio-hydrogen; Biofuel; Bioremediation; Feedstock; Hydrothermal liquefaction; Wastewater treatment