May 29, 2017
Sanitation
Valorization: A Process For Sustaining Life
The need to offer quality feed and fuel has become a burning issue in the world as we know it.
Climate change, pollution, and energy crisis are a few of the issues which are major issues that the human race will have to deal with in the upcoming years.
Mankind has gradually infringed upon Nature’s reservoirs due to the ever-increasing human population.
Pollution of the world’s natural resources due to industrialization has already brought us on the verge of catastrophic consequences.
Therefore, sustainable development is the key issue that global policymakers need to address.
Finding innovative strategies to accommodate sustainable development along with safe disposal of generated waste is the need of the hour.
Waste is generated from various sectors, viz. agriculture, household, industries, etc., in an extensive amount, creating pertinent questions related to waste management.
Metropolitan cities in today’s world have been grappling with issues related to irresponsible waste disposal, but it has not converted into awareness, leading to cutting waste.
Many methods exist for addressing this issue, one being valorisation of waste.
Valorization could be defined as a process of converting waste into valuable merchandise which could be industrially important chemicals, fuels, materials, etc.
Waste valorization is not a new concept; it has been in existence for long enough; it has now been brought up by society due to the fast deprivation of natural resources and the increased waste generation worldwide.
Many of the waste valorization strategies have been implemented, a few of which are as follows:
Chemical Engineering
Flow chemistry is already being used by various industries for processing waste into valuable products, particularly in the food industry.
A few of the pros of continuous flow chemistry are the ease of scale-up and high yield.
The cons are huge energy requirements for degrading highly stable bio-polymers and recalcitrant compounds (ex. Lignin).
Pyrolysis
The second most used strategy for valorization is pyrolysis, a method in particular that has been used for the generation of bio-oils.
Bio-oil has a low viscosity index and is a mixture of short chains of ketones, aldehydes, and carboxylic acid.
There are a few reports of furniture waste saw dust being converted into bio-oil by using a fluidized bioreactor, which could yield 57% bio-oil, as reported by Hoe et al. (2014).
Microbial Biodegradation
The third strategy is Microbial biodegradation of waste in order to generate valuable products (Biofuels, Biofertilizers, etc.).
Bio conversion has been in the picture for more than a decade now, this is considered to be a green method for converting a waste into commercially and industrially valuable products.
One of the examples of this could be the generation of biofuels from agricultural waste.
Biofuel- Valorization of Agriculture Waste
The generation of bio-fuels from crops is now a technology that has failed to pick up as much momentum as we would have liked; in comparison, microbial fuels show much greater promise.
Many microbes such as algae, bacteria, fungus and yeasts have the ability to accumulate oil, such microbes are known as oleaginous microbes.
Microbial oils can be used as a potential feedstock for the generation of biodiesel in the future.
The extent of lipid accumulation of an oleaginous microbe is determined by its genetic constitution. The yield of SCO can be increased by genetic manipulation as well as by varying its growth parameters.
One of the main strengths of India is its agriculture sector, various amounts of waste is generated in this sector in day to day basis, which is either used as feedstock for cattle, some is used as fuel and other is being just dumped into landfills.
By valorizing the waste material generated in this sector for the production of Biofuels could be beneficial.
Here, the question of the crop for food vs. fuel can be solved by utilizing the waste itself for the generation of biofuels.
Various substrates like corn cobs, sugarcane, beet molasses, grain husk, cotton stalk waste, oil cake meals, etc., still have high nutritional value; such agricultural by-products can be used as a whole for production of the microbes which could accumulate lipids generally termed as oleaginous microbes, further, these lipids (single cell oils) can later be used as a feedstock for generation of biodiesel.
Microbes that are reported oleaginous microbes and can be used for the production of biofuels with favorable substrates are :
- Bacteria- Bacillus subtilis (sugarcane molasses waste), Rhodococcusopacus (Corn cob);
- Fungus- Aspergillus terreus (Pineapple peels, sugarcane molasses, oil peat), Mucor spp. (oil peat, cheese whey), Colleototricum sp. (Beet molasses, orange wastes), Alterneria spp. (Grain husk)
- Yeast– Yarrowia lipolytica (Saw dust and grain husk waste)
- Actinomycetes- Thermomonospora fusca and Streptomycetes spp.(Wheat bran and Oatmeal husk) They are known to accumulate approximately 70% of lipids under stress conditions
Extensive disposal of waste is deteriorating landfills in many parts of the world, and landfills can be used for better purposes such as waste valorization.
Joint efforts to form a green technology across various disciplines, such as bioengineering to chemistry, biotechnology to environmental sciences, and economics as well could lead towards the betterment of Mother Nature.
A step towards sustainable development by waste valorisation could be a step to a healthy and green future.
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