Dual role of microalgae: Phycoremediation of domestic wastewater and biomass production for sustainable biofuels production (original) (raw)
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World journal of microbiology & biotechnology, 2016
Untreated wastewaters have been a great concern and can cause major pollution problems for environment. Conventional approaches for treating wastewater involve tremendous capital cost, have major short comings and are not sustainable. Microalgae culture offers an interesting step for wastewater treatment. Microalgae serve the dual purpose of phycoremediation along with the production of potentially valuable biomass, which can be used for several purposes. The ability of microalgae to accumulate nitrogen, phosphorus, heavy metals and other toxic compounds can be integrated with wastewater treatment system to offer an elegant solution towards tertiary and quaternary treatment. The current review explores possible role of microalgal based wastewater treatment and explores the current progress, key challenges, limitations and future prospects with special emphasis on strategies involved in harvesting, boosting biomass and lipid yield.
2017
Increasing population and Industrialization are key pollutant contributors in water bodies. These wastes are highly hazardous for humansand ecosystem and require a comprehensive, effective treatment before discharge into water bodies. Over the years, many up gradations have been introduced in traditional water treatment methods which were expensive and ineffective especially for removal of heavy metals. Micro alga has been gaining attention due to its mutual benefit in wastewater treatment and for valuable algae biomass production. Waste water especially sewage and industrial effluents are rich in pathogenic organisms, organic, inorganic and heavy metals that adversely affect human and aquatic life. Algae use these inorganic and heavy metals for its growth. In addition it also reduces pathogenic organism and release oxygen to be used by bacteria for decomposition of organic compounds in secondary treatment. In this review, we will discuss potential of microalgae in wastewater treatm...
Microalgae: A Renewable Source for Wastewater Treatment and Feedstock Supply for Biofuel Generation
Biointerface Research in Applied Chemistry
The search and exploitation of renewable clean energy sources have become crucial, because of the developing day by day interest for clean water and energy affected by the improvement of the economy, population, industrialization, urbanization, insufficient energy, climate abnormalities, and environmental pollution. The major cause of emissions of harmful gases into the environment is due to the high utilization of petroleum derivatives. In this way, it is paramount to explore environmentally sustainable energy sources for feasible advancement, to satisfy these expanding energy demands and to secure the environment. To mitigate these global problems, academic, industrial, and governmental sectors have engaged in a lot of brainstorming and research to surmount these difficulties, which have brought a steady flow of new information in the area of cultivation of microalgae in innovative technologies including photobioreactors and high rate algal ponds. In this respect, biomass generatio...
International Journal of Environmental Science and Technology, 2014
Discharge of untreated domestic and industrial wastewater into aquatic bodies is posing a serious eutrophication threat, leading to a slow degradation of the water resources. A number of physical, chemical and biological methods have been developed for the treatment of wastewaters; among these, the use of microalgae is considered as a more eco-friendly and economical approaches. Microalgae are versatile organisms which perform multiple roles in the environment-bioremediation of wastewater, gleaning of excess nutrients and in turn, generate valuable biomass which finds applications in the food, biofuel and pharmaceutical industries. They are currently being utilized to reduce the high nutrient load (especially N and P) from wastewaters, which fulfill the growth requirements of microalgae, making it a suitable cultivation medium for biomass production. The present review represents a comprehensive compilation of reports on microalgal diversity of wastewaters, followed by a critical overview of their utilization, suitability and potential in bioremediation visa -vis biomass production. This review also emphasizes the superiority of polyalgal and consortial approaches in wastewater treatment, as compared to the use of unialgal inocula, besides providing useful pointers for future research needs in this area.
Journal of Applied Phycology, 2016
The utilization of microalgae for wastewater treatment represents an attractive opportunity for wastewater valorization through the use of the produced biomass. Five strains of microalgae were isolated from municipal wastewater and grown in autoclaved and non-autoclaved effluent at 30°C and 150 μmol photons m −2 s −1 to study biomass production, nutrient removal, and the biochemical composition of the biomass. All strains reached high biomass productivity (35.6 to 54.2 mg dry weight L −1 day −1) within 4 days of batch culturing. In this period, ammonium-N and phosphate were reduced by more than 60 and 90 %, respectively. The high growth rate (0.57 to 1.06 day −1) ensured a rapid removal of nutrients and thereby a short retention time. By the fourth day of cultivation, the algal biomass contained 32 % protein, but only 11 % lipids and 18 % carbohydrates. It was found that the biomass was a suitable raw material for biogas production by anaerobic digestion. Biodigestion of obtained biomass was simulated by employing the Aspen HYSYS modeling software, resulting in methane yields comparable to those found in the literature. The elemental analysis of the algal biomass showed very low concentrations of pollutants, demonstrating the potential of use of the digestate from biodigestion as a bio-fertilizer.
Bioresource technology, 2016
Dairy wastewater collected from local dairy industry was used as a growth media (without any pre-treatment) for the cultivation of microalgae Acutodesmus dimorphus. The level of COD reduced over 90% (from 2593.33±277.37 to 215±7.07mg/L) after 4days of cultivation; whereas, ammoniacal nitrogen was consumed completely (277.4±10.75mg/L) after 6days of cultivation. Dry biomass of 840 and 790mg/L was observed after 4 and 8days of cultivation, respectively, which is about 5-6 times more than that of BG-11 grown culture (149mg/L after 8days). This biomass contains around 25% lipid and 30% carbohydrate, which can be further converted into biodiesel and bioethanol, respectively. Theoretical calculations based on the recently reported conversion yield suggest that 1kg biomass of A. dimorphus might produce around 195g of biodiesel and 78g of bioethanol, which sums up to 273g of biofuels.
An integrated approach for biofuel and fertilizer production using microalgae grown in wastewater
2023
Microalgae are recognized as potential candidates for resource recovery from wastewater and are projected for biorefinery models. Therefore, this study was undertaken to evaluate the potential of poultry litter and municipal wastewater as nutrient and water sources, for the cultivation of Acutodesmus obliquus for lipids production for biodiesel application. The efficacy of lipid extracted biomass (LEA) as fertilizer for mung bean crops was also assessed in microcosm. A. obliquus cultivation in acid pre-treated poultry litter extract (PPLE) showed maximum biomass production of 1.90 g L-1 , which was 74.67% and 12.61% higher than the raw poultry litter extract (RPPE) and BG11 respectively. Higher NO3-N, NH3-N, and PO4-P removal of 79.51%, 81.82%, and 80.52% respectively were observed in PPLE as compared to RPLE treatment. The highest biomass (140.36 mg L-1 d-1), lipids (38.49 mg L-1 d-1), and carbohydrates (49.55 mg L-1 d-1) productivities were observed in the PPLE medium. The application of LEA as a fertilizer for mung bean crops showed improvement in plant growth and soil microbial activity. A maximum increase in organic carbon (59.5%) and dehydrogenase activity (130.8%) was observed in LEA amended soil which was significantly higher than chemical fertilizer (CF) control in 30 days. Whilst plant fresh weight and leaf chlorophyll in the LEA amended soil was comparable to whole algal biomass (WA) and CF control. The findings of the present study could be a basis for sustainable biorefinery for the valorization of wastewater for the production of microalgae-derived biofuel and byproducts for agricultural applications. vii ACKNOWLEDGEMENTS My foremost gratitude goes to the creator of all, God Almighty, for giving me the strength and courage to complete this work. I couldn't have made it this far without his guidance. I would also like to extend my sincere gratitude to the following people who played a major role in ensuring that this work was accomplished: My main supervisor, Professor Faizal Bux, thank you for granting me an opportunity to be part of the Institute for Water and Wastewater Technology, especially the algae team. Without your constant guidance, endless encouragement, and inspiration, the completion of this master's work wouldn't have been possible.
Improving the feasibility of producing biofuels from microalgae using wastewater
Biofuels have received much attention recently owing to energy consumption and environmental concerns. Despite many of the technologies being technically feasible, the processes are often too costly to be commercially viable. The major stumbling block to full-scale production of algal biofuels is the cost of upstream and downstream processes and environmental impacts such as water footprint and indirect greenhouse gas emissions from chemical nutrient production. The technoeconomics of biofuels production from microalgae is currently unfeasible due to the cost of inputs and productivities achieved. The use of a biorefinery approach sees the production costs reduced greatly due to utilization of waste streams for cultivation and the generation of several potential energy sources and value-added products while offering environmental protection. The use of wastewater as a production media, coupled with CO2 sequestration from flue gas greatly reduces the microalgal cultivation costs. Conversion of residual biomass and by-products, such as glycerol, for fuel production using an integrated approach potentially holds the key to near future commercial implementation of biofuels production.
Coupling wastewater treatment, biomass, lipids, and biodiesel production of some green microalgae
Environmental Science and Pollution Research
This study demonstrates the combination of wastewater treatment and green microalgae cultivation for the low-cost production of lipids as a feedstock for biodiesel production. Three green microalgal species were used: Chlamydomonas reinhardtii, Monoraphidium braunii, and Scenedesmus obliquus. Nutrient, heavy metals and minerals removal, biomass productivity, carbohydrate, protein, proline, lipid, and fatty acids methyl ester (FAMEs) contents besides biodiesel properties were evaluated. The results showed that all algal species were highly efficient and had the potential to reduce nitrate, ammonia, phosphate, sulfate, heavy metals (Zn2+, Cu2+, Mn2+, and Fe2+), calcium, magnesium, sodium, and potassium after 10 days of algal treatment compared to initial concentrations. The removal efficiency of these parameters ranged from 12 to 100%. The growth rates of M. braunii and S. obliquus cultivated in wastewater were significantly decreased compared to the control (synthetic medium). In con...
Production and harvesting of microalgae for wastewater treatment, biofuels, and bioproducts
Biotechnology Advances, 2011
The integration of microalgae-based biofuel and bioproducts production with wastewater treatment has major advantages for both industries. However, major challenges to the implementation of an integrated system include the large-scale production of algae and the harvesting of microalgae in a way that allows for downstream processing to produce biofuels and other bioproducts of value. Although the majority of algal production systems use suspended cultures in either open ponds or closed reactors, the use of attached cultures may offer several advantages. With regard to harvesting methods, better understanding and control of autoflocculation and bioflocculation could improve performance and reduce chemical addition requirements for conventional mechanical methods that include centrifugation, tangential filtration, gravity sedimentation, and dissolved air flotation. There are many approaches currently used by companies and industries using clean water at laboratory, bench, and pilot scale; however, large-scale systems for controlled algae production and/or harvesting for wastewater treatment and subsequent processing for bioproducts are lacking. Further investigation and development of large-scale production and harvesting methods for biofuels and bioproducts are necessary, particularly with less studied but promising approaches such as those involving attached algal biofilm cultures.