Integrated Microalgae-based Wastewater Treatment and Value-added Product Production: A Step towards Sustainable Development Goals Kanika Arora, Student of School of Biotechnology, Shoolini University
p: kanika462a@gmail.com
ABSTRACT Every year about 3.4 million people died and many suffered from a plethora of waterborne diseases worldwide according to WHO. The major culprit behind this nuisance is the reckless discharge of polluted water from many industries and even from STP which does not meet the stringent regulatory standards. The effluent containing a high load of nutrients like nitrates and phosphates and toxic metals cause depletion of limited freshwater reserves and leads to eutrophication. This challenge can be easily resolved by introducing microalgae in wastewater treatment. These phototrophs utilize C02 from the environment and in turn, produce oxygen for the growth of sludge bacteria. Algae can consume the urea, phosphates, and heavy metals such as magnesium, zinc, lead, cadmium, arsenic, etc. for its growth and also aid in BOD and COD removal besides removing coliform bacteria from the sewage water. The biomass produced can further be converted into valuable products such as biofuel, feed, biofertilizer, bioplastic, and exopolysaccharides. Therefore, microalgae is an elixir of life and can help meet sustainable development goals.
CULTIVATION SYSTEMS
INTRODUCTION Water constitute 70% of earth surface but freshwater is a scarce commodity. India is a agrarian economy and consume almost 78% of it for crop cultivation and other for industrial and domestic needs. Therefore, municipal sewage water is the important water source which needs to be replenished and recycled for further use as it consist of 99.9% water and only 0.1% solids which make it unfit for consumption. Wastewater chiefly constitute organic (volatile) solids like carbohydrate, proteins and fats and latter (inorganic) is mostly sand, grit, nutrients, heavy metals etc. Furthermore, biological component i.e. microbes and nematodes pose the great threat to life if not properly removed. This wastewater conditions are most favourable for microalgae to grow and divide in a synergistic manner with a sludge bacteria. Phycoremidiation in wastewater treatment not only render promising reclamation of nutrients but can also absorb oil slicks and antibiotics from pharmaceutical wastes. The biomass has incredible application in various sectors and provide unfettered gateway to sustainable, zerowaste and circular biobased economy.
Open Ponds
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Raceways ponds
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Stabilization ponds
Integrated Systems
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SDG Microalgae has enormous potential to realize all 17 Sustainable Development Goals and deeply impact the environment. It can transform our present into sustainable and more efficient living. Even algae grown in wastewater systems can sway the nation in many folds.
HRAP Biofilm PBR Immobilized Systems
Table 2. It disclose various ways in which microalgae can impact SDGs
• Closed PBRs
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Flat-plate
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Tubular PBR
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Membrane PBR
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Plastic PBR
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Solid-sate PBR
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Figure 2. Categorization of various microalgae cultivation systems into open, closed and integrated (hybrid) systems for wastewater treatment
FACTORS
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There are many important factors that governs the algal yield that are need to be maintained while culturing. pH
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Temperature (20-30°C)
(6-8.75)
OBJECTIVES ➢ To encourage the use of microalgae in wastewater treatment and to illuminate its potential applications in various sectors ➢ To envisage the microalgae as most suitable candidate to achieve SDGs in India and to overcome environmental perturbations.
(16h/8h)
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Microalgae is a promising source of clean energy. Algal biomass can be processed to produce thirdgeneration biofuel like biodiesel, biobutanol, bioethanol, biogas and microalgae microbial fuel cell (MMFC) The main biorefinery concept is the maximum utilization of biomass that can serve as a substitute to petroleum-based fuels
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Microalgae is a plantlike organisms that utilize CO2 from the environment for photosynthesis and produce about 70% of Earth’s oxygen Algae are 400 times more efficient than trees for removing major green house gas from the atmosphere and help make the environment cooler for the planet by reducing the carbon footprint
Nutrients
Salinity
(N, P, K)
( 20-30%)
➢ It should be designed in a sustainable and cost effective manner to ensure higher biomass yield by taking various factors under consideration
Figure 3. Various factors affecting microalgal growth with their optimum concentrations
Many concurrent technologies are used widely from the past many years to absorb or remove nutrients from the wastewater stream. Many are energy-intensive and costly solutions with chemicals used as the prime substrate. They have their advantages as well as limitations. While algae technologies along with conventional biological treatment will expedite the reclamation rates and will address the externalities most sustainably.
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Many species of microalgae are valorised all over the globe to be used in phycoremidiation of municipal wastewaters Algae can utilize the toxic compounds like heavy metal and dye in water besides reducing the organic load It can make the water fit for agricultural use and for growing fishes
➢ The integrated microalgae-based wastewater treatment is an economically viable and most efficient techniques
(10K-20K lux)
(Optimum Concentration)
CURRENT TECHNOLOGY
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CONCLUSION
Light Intensity
Factors affecting Microalgal growth
Light Duration
Microalgae is an immense source of protein, PUFA, essential minerals and vitamins; and epitomise high nutrition diet Algae like Spirulina is cultivated worldwide for its high-quality protein Microalgae grown from wastewater are also used as bio stimulants and biofertilizer to increase crop production and alleviate hunger
ALGAL PRODUCTS ➢ Microalgae grown in wastewater streams have enormous applications in various sectors especially as potential biofuel, bioplastic (PBH) and biofertilizer. ➢ Several industries have adopted phycoremidiation to maintain their discharge standards and to perform well in corporate social responsibility. Besides, they gain huge profits by selling the algae-based products like biofuel, feed and fertilizer to the market.
➢ Bottlenecks like scalability and purification cost; and extraction method can be controlled by consenting advanced methods
FUTURE PROSPECTS ➢ Microalgae consortium, biofilm and immobilized integrated algal system are advanced techniques that foster promising results and economic stability ➢ Techniques like genetic engineering, strain development and synthetic biology will provide great thrust to this technology in near future
High value Products
Algal Products
➢ Scientific research and development are required in the field of phycology for further utilization of biomass into valuable products to create more jobs in a bio-based economy
Pharmaceuticals, nutraceuticals and cosmetics Low-value Products Biofuels and Biofertilizers
Figure 4. Schematic representation of value-added algal products
Microalgae Chlorella stigmatophora Botryococcus braunii Scenedesmus sp Lupinus termis Gyrodinium impudicum
Properties Metal-chelating property in EPS
Applications Water purification
High lipid content High PBH synthesis High PGR production anti-viral activity, immunostimulatory activity, bio flocculent Anti-oxidants, including pigments, phenolics,
Biofuel production Biopolymer production Biofertilizer Pharmaceutical
Reference [1] [2] [3] [4]
Desmodesmus sp. Nutraceutics [5] and Phaeodactylum tricornuotom Figure 1. Representing algal technology as the most promising approach than Table 1. Properties and applications of various microalgae grown in WW many perpetual techniques for nutrient removal
REFERNCES 1. Kaplan, D., Christiaen, D. & Arad, S. (Malis). Chelating Properties of Extracellular
Polysaccharides from Chlorella spp. Applied and Environmental Microbiology 53, (1987). 2. Raihan, T. Integrated Biodiesel Production System by using Botryococcus braunii as Microalgae feedstock. http://www.academia.edu/download/62171035/Biorefineries_Assignment_3_Compile2 0200222-112273-18m62fo.pdf (2019). 3. López Rocha, C. J. et al. Development of bioplastics from a microalgae consortium from wastewater. Journal of Environmental Management 263, 110353 (2020). 4. Lee, C.-K. et al. Antiviral Effects of Sulfated Exopolysaccharide from the Marine Microalga Gyrodinium impudicum Strain KG03. Antiviral Research 78, A59 (2008). 5. Safafar, H., van Wagenen, J., Møller, P. & Jacobsen, C. Carotenoids, Phenolic Compounds and Tocopherols Contribute to the Antioxidative Properties of Some Microalgae Species Grown on Industrial Wastewater. Marine Drugs 13, 7339–7356 (2015).