Phycoremediation – a clean technology for water pollution abatement
Prepared By:Rashmi Paliwal
IntroductionImmobilized MicroalgaeTransgenic AlgaeAdvantages of Algal TechnologyApplications
World is facing the problems with a wide variety ofpollutants.Many methods are available for the removal of thesepollutants but they are not widely acceptable.Biological methods are often preferred since they havemany advantages like rapid biodegradation rates, lowsludge yield and excellent process stability.
Use of macro-algae or micro-algae for the removal or biotransformationof pollutants, including nutrients and xenobiotics from wastewater andCO2 from waste air.Naturally occurring phenomenonAlgae utilize the wastes as nutritional sources and enzymatically degradethe pollutants.The xenobiotics and heavy metals are known to be detoxified/transformed/or volatilized by algal metabolism.An integrated algae and bacterial based wasted water system canremove a wide variety of contaminants.
Division Algal Species Metal(Common Name) Chlorella sp. and Scenedesmus sp. Cu, Cd Cladophora, Thalassiosira Cu, Zn and Cd pseudonana and Ditylum birghtwellii Chlorella vulgaris Zn, Cd Chlorophyta Scendesmus acutus Cr (Green algae) Scenedesmus obliquus Co Scenedesmus subspicatus Al Scenedesmus quadricauda Zn, Cu and Ni Sargasuum nutan Au Phaeophyta Ascophyllum nodosum, Au, Cd, Co, Ni, Pb (Brown algae) S. Vulgare Cu, Ni, Pb, Cd Fucus Vesiculosus Pb, Ni, Cu, Cd, Zn Laminaria japonica Zn, Cu Rhodophyta Acrosorium uncinatum Cu, Zn, Ni, Pb (Red algae) Davis, et.al., (2003)
Immobilization: Transfer of cells from a free state to a state in which they are confined/localized in a certain defined region of space. Advantages: Reusing the biomass after regeneration. Avoids filtration of the treated wastewater. More than one microorganism can be immobilize .
Microalgae species Immobilizing Material PollutantChlorella homosphaera Alginate Cd, Au, ZnC. vulgaris Alginate, k-Carrageenan Cd, Cu, Zn Polyurethane foam Silica gel HgChlamydomonas reinhardtii Alginate Cd, Pb, HgOscillatoria sp. Alginate CdScenedesmus acutus Alginate, k-Carrageenan Cd, Cr Polyurethane foam ZnScenedesmus quadricauda Alginate Ni, Zn, CuChlorella regularis Polyacrylamide UraniumSpirulina platensis Silica gel Cd
Contd… Microalgae species Immobilizing Pollutant MaterialPhormidium laminosum Polysulphone foam Mixture of Cu, Fe, Ni, Zn and epoxy resinChlorella salina Alginate Mn, Zn, CoSargassum baccularia Polyvinyl alcohol CuChlorella emersonii; C. vulgaris Alginate Organotin Compounds (Biocides)Phaeodactylum tricornutum Alginate linear alkylbenzene sulphonate (LAS) a surfactantChlorella sp.; Phormidium sp.; Capron fibers Mix of phenols, oil spillScenedesmus obliquus; (synthetic) and heavy metalsStichococcus sp. Bashan & Bashan, (2010)
Transgenesis in algae is a complex but fast growing technique. Genetic manipulations in algae to improve their detoxification ability. Very few species of microalgae have been genetically transformed with efficiency.Requirement of Algal Transformation: Previous molecular, biochemical, physiological or ecological knowledge of the target species. Extensive sequence information.
Species UtilizationGreen algaeChlamydomonas reinhardtii biomass from transgenics for animal health and feed; bioremediation,Ulva spp. environmental monitoring; production of recombinant proteins. biomass for food and feed; extracts for cosmetics, wastewaterMonostroma spp. Treatment. biomass for food; wastewater treatment.Brown algaeLaminaria spp. alginate for food, pharmaceuticals, and cosmetics; biomass for foodSargassum spp. and feed; wastewater treatment.Macrocystis pyrifera Wastewater treatment. alginate for pharmaceuticals, cosmetics, food, and textile printing;Lessonia spp. biomass for feed and fuel; wastewater treatment. alginate for pharmaceuticals, cosmetics, food, and textile printing; wastewater treatment. Hallmann, (2007)
Cost parameter Conventional Phycoremediation Annual cost benefit Effluent TreatmentAcidity - caustic soda Algal treatment Rs. 50 lakhs spentHigh levels of for caustic sodadissolved carbon annually is saveddioxide (100%).Sludge formation About 290 tonnes of There is no residual The sludge disposal sludge produced sludge. cost Rs. 3 lakhs annually from this annually. This cost treatment. is saved.Structures and 11,000 Sq Mtrs of 3000 sq mtrs of tank About 75% of thespace. masonry tank for for containing and effluent treatment evaporating the evaporating the facility space is effluent effluent. released. http://phycospectrum.com/moresnap.html
Phycoremediation is a multi-faceted effluenttreatment process. As a green cell factory algae can tackle simultaneously more than one problem. However, the development of more efficient pollutants removal algal systems requires further research in key areas.
Bashan, L.E. and Bashan, Y., (2010). Immobilized Microalgae for Removing Pollutants: Review of Practical Aspects. Bioresource Technology. 101: 1611–1627 Davis, T.A., Volesky, B., and Mucci, A., (2003). A review of the biochemistry of heavy metal biosorption by brown algae. Water Research., 37: 4311–4330 Hallmann A. (2007) Algal Transgenics and Biotechnology. Transgenic Plant Journal. 1: 81-98 Kobayashi, H. and Rittman, B.E. (1982). Microbial removal of hazardous organic compounds. Environ. Sci. Technol., 16: 70-183 Torres, M.A., Barros M.P., Campos, S.C.G., Pinto, E., Rajamani, S., Sayre, R.T. and Colepicolo, P. (2008). Biochemical Biomarker in Algae and Marine Pollution: A review. Ecotoxicology and Environmental Safety. 71: 1-15 http://phycospectrum.com/moresnap.html www.oldcastleprecast.com http://www.nasa.gov/centers/ames/greenspace/ www.google.com