Biorefinery Processes and Products (Microalgae and Water Hyacinth) Research Paper

Biorefinery concept

Biorefinery concept revolves around the facilities and processes that convert biomasses to biofuels and value-added chemical compounds (Cherubini, 2010; Taylor, 2008). Photosynthesizing plant materials provide excellent sources of energy and chemicals (Rabelo et al., 2011). By adopting renewable sources of energy, it implies that the world will never run out of energy for domestic and industrial purposes. Biorefineries produce many products at the same time by taking advantage of the chemically diverse compounds found in biomasses and their intermediaries. However, research demonstrates that biorefinery is under-exploited, and the concept of energy production has many research and business opportunities. The concept utilizes knowledge from microbiology, biotechnology and physics (Menon & Rao, 2012).

Biorefinery processes

A typical biorefinery could involve the following four processes:

1. Pre-treatment
2. Enzymatic hydrolysis
3. Fermentation and bio-reactions
4. Separation and recovery

In the first process, biomass is fed into a biorefinery plant. The biomass could be algae, grass or water hyacinth, among other photosynthetic materials. At this stage, the biomass is mixed with chemicals and the product from the pre-treatment tank is biomass pulp. The biomass pulp is directed to the second biorefinery process where grains and enzymes are fed into the tank. This second process involves the enzymatic breakdown of the biomass pulp by enzymes. Enzymes that are used to digest the biomass pulp are chosen based on the properties of the biomass raw materials. It could be easy to predict the properties of biomass pulp based on the raw materials used. The enzymatic process leads to the formation of simple sugars. The simple sugars are fed into the third stage of the biorefinery plant (Octave & Thomas, 2009). The processes at the third stage involve fermentation and bio-reactions. Microorganisms are mixed with the simple sugars to initiate fermentation and bio-reactions. The fermentation and bio-reactions lead to the formation of bio-products which are fed into the fourth and final process of a biorefinery. The final process involves separating and recovering the major products of the biorefinery (Octave & Thomas, 2009). The end-products could be renewable fuels, feed products and/or specialty chemicals. The four processes discussed above are well designed to ensure that a biorefinery plant is economically viable. In other words, a cost-benefit analysis should prove that a biorefinery plant produces products that have higher economic value than the production cost (Octave & Thomas, 2009).

Biomasses in our project

Microalgae

Research demonstrates that some species of algae could be utilized as biomass in biorefineries to yield ethanol (Efremenko et al., 2012). Ethanol is a source of energy for domestic and industrial uses. There have been issues that limited research exists in the utilization of microalgae in ethanol production, and more research is needed to fully utilize the benefits of algae in biorefineries (Parmar, Singh, Pandey, Gnansounou & Madamwar, 2011).

Algae are either autotrophic or heterotrophic. Autotrophic algae capture energy from the sun to synthesize their own food through photosynthesis. The food manufactured by the autotrophic algae is stored in the form of carbohydrates. On the other hand, heterotrophic algae obtain small molecules from the environment and convert them to fat, oil or proteins. Algae are either microalgae (microscopic) or macroalgae (macroscopic). Microalgae have high ability for converting photons, and this implies that they could produce a lot of carbohydrates needed in a biorefinery over a short period of time (Chen et al., 2011; Chen et al., 2013; John, Anisha, Nampoothiri & Pandey, 2011). Some biorefineries could use petroleum as the source of energy for heating biomass. Microalgae have been confirmed to withstand high levels of carbon dioxide from petroleum-based sources of energy (Demirbas, 2011).

Microalgae can grow in many habitats across the world, and they have been shown to have the highest growth rates across the world. Microalgae could withstand diverse temperatures and pH conditions. Microalgae are single-celled organisms which do not waste energy in translocation of molecules between tissues (Moazami et al., 2012).

The use of microalgae as biomass for biofuel production in biorefineries is feasible because they could be grown in optimal conditions and increase exponentially over a short period of time (Oncel, 2013). The rapid growth favors mass production of biofuels because of continuous input of raw materials (Mata, Martins & Caetano, 2010). The problem that scientists could solve in the future is designing a microalgae biorefinery that could produce large amounts of biofuels at a low cost. Upcoming biotechnology firms have taken an initiative to solve this problem by adopting biotechnology approaches in cultivation of microalgae for biorefineries (Ziolkowska & Simon, 2013). The open cultivation of microalgae could expose them to their predators, and this could result in big losses (Harun & Danquah, 2011). The processes involved in microalgae biorefineries are very expensive and, in most cases, do not make economic sense (Singh & Gu, 2010). Nevertheless, the adoption of microalgae for large-scale production of biofuels in biorefineries has many opportunities in the future (Lam & Lee, 2012; Pienkos & Darzins, 2009).

Summary of chemical components in microalgae

The percentages of chemical components in microalgae are not fixed because they depend on the species of microalgae. The following chemical components are found in microalgae:

1. Proteins
2. Carbohydrates
3. Nucleic acid
4. Fatty acid (oil)

The fatty acid component is crucial in microalgae biorefinery because it is isolated and converted into ethanol and methanol (biodiesel). Ethanol and methanol are used as sources of energy for industrial and domestic purposes.

Water hyacinth

Water hyacinth is an aquatic plant that grows in both clean water and wastewater (Abdel-Fattah & Abdel-Naby, 2012; Bayrakci & Koçar, 2014). Research shows that the plant cleans water by filtering nitrogen and oxygen supply. The plant has high rates of reproduction, taking about 8 days to duplicate. Large amounts of cellulose and carbohydrates are contained in the plant, and the chemical compounds make the plant ideal for producing biofuels. Research shows that the amount of biofuels obtained from water hyacinths is based on the type of pre-treatment used in a biorefinery. Proper pre-treatment measures lead to the realization of large amounts of biofuels while poor treatment approaches result in small amounts of biofuels. Proper pre-treatment uses sodium hydroxide, alkaline peroxide, peracetic acid and sodium chlorite. The chemicals ensure that there is proper digestion of hyacinth fibers to yield biomass pulp (Thiripura Sundari & Ramesh, 2012).

Water hyacinth is a menace in many countries because the plant grows at very high rates and, in most cases, the growth is uncontrollable. If the plant invades seashores that are used for recreational purposes by tourists, then it could lead to major financial losses. Many countries have not found best approaches to eliminate the plant from their water bodies. The use of chemicals to eliminate water hyacinth from water has been rejected because the chemicals could lead to loss of human lives if human beings consume the water having chemicals. However, some countries have adopted approaches that involve harvesting water hyacinth for biofuel production in biorefineries. If water hyacinth biorefineries are designed well, they could produce large amounts of biofuels (Thiripura et al., 2012).

Chemical analysis of water hyacinth needs to be done so that to determine the expected quantities of biofuels (Singh & Bishnoi, 2013). Research demonstrates that leaves of water hyacinths growing in sewage have 33% of crude protein. People aiming at designing efficient water hyacinth biorefineries should determine the environments from which to obtain the plant biomass for biofuel production. The environment determines the chemical composition of the plant which impacts the quality and amounts of biofuels. The main challenge facing production of biofuels from water hyacinths is lack of appropriate technologies to use in biorefineries. Poor technologies in biorefineries result in production of small volumes of biofuels. In such circumstances, the cost of production exceeds the economic benefits of the biofuels produced. On the other hand, good technologies go a long way in ensuring that water hyacinth biorefineries are efficient and produce biofuels that have more economical value than the cost of production (Ganguly, Chatterjee & Dey, 2012). The use of water hyacinths to produce biofuels is largely untapped in many countries across the world. The adoption of the right approaches in utilizing water hyacinths for biofuel production will go a long way in increasing the amount of biofuels produced across the world (Malik, 2007).

Summary of chemical components in water hyacinth

The percentages of chemical components of water hyacinth have been found to vary based on the environment supporting its growth. However, the following are the chemical components and ranges of percentage compositions:

1. Protein (48%-51%)
2. Total lipids (15%-18%)
3. Carbohydrates (24%-27%)
4. Fiber (1.5%-1.8%)
5. Ash (5.5%-6%)

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