phycoremediation – a clean technology for water pollution abatement
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Prepared By:Rashmi Paliwal
IntroductionImmobilized MicroalgaeTransgenic AlgaeAdvantages of Algal TechnologyApplications
World is facing the problems with a wide variety of pollutants.
Many methods are available for the removal of these pollutants but they are not widely acceptable.
Biological methods are often preferred since they have many advantages like rapid biodegradation rates, low sludge yield and excellent process stability.
Use of macro-algae or micro-algae for the removal or biotransformation of pollutants, including nutrients and xenobiotics from wastewater and CO2 from waste air.
Naturally occurring phenomenon
Algae utilize the wastes as nutritional sources and enzymatically degrade the 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 can remove a wide variety of contaminants.
Division
(Common Name)
Algal Species Metal
Chlorophyta
(Green algae)
Phaeophyta
(Brown algae)
Rhodophyta
(Red algae)
Chlorella sp. and Scenedesmus sp.
Cladophora, Thalassiosira pseudonana and Ditylum birghtwellii
Chlorella vulgaris
Scendesmus acutus
Scenedesmus obliquus
Scenedesmus subspicatus
Scenedesmus quadricauda
Sargasuum nutan
Ascophyllum nodosum,
S. Vulgare
Fucus Vesiculosus
Laminaria japonica
Acrosorium uncinatum
Cu, Cd
Cu, Zn and Cd
Zn, Cd
Cr
Co
Al
Zn, Cu and Ni
Au
Au, Cd, Co, Ni, Pb
Cu, Ni, Pb, Cd
Pb, Ni, Cu, Cd, Zn
Zn, Cu
Cu, Zn, Ni, Pb
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 Pollutant
Chlorella homosphaera
C. vulgaris
Chlamydomonas reinhardtii
Oscillatoria sp.
Scenedesmus acutus
Scenedesmus quadricauda
Chlorella regularis
Spirulina platensis
Alginate
Alginate, k-Carrageenan
Polyurethane foam
Silica gel
Alginate
Alginate
Alginate, k-Carrageenan
Polyurethane foam
Alginate
Polyacrylamide
Silica gel
Cd, Au, Zn
Cd, Cu, Zn
Hg
Cd, Pb, Hg
Cd
Cd, Cr
Zn
Ni, Zn, Cu
Uranium
Cd
Microalgae species Immobilizing Material
Pollutant
Phormidium laminosum
Chlorella salina
Sargassum baccularia
Chlorella emersonii; C. vulgaris
Phaeodactylum tricornutum
Chlorella sp.; Phormidium sp.;
Scenedesmus obliquus;
Stichococcus sp.
Polysulphone foam
and epoxy resin
Alginate
Polyvinyl alcohol
Alginate
Alginate
Capron fibers
(synthetic)
Mixture of Cu, Fe, Ni, Zn
Mn, Zn, Co
Cu
Organotin Compounds
(Biocides)
linear alkylbenzene
sulphonate (LAS) a
surfactant
Mix of phenols, oil spill
and heavy metals
Contd…
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 Utilization
Green algae
Chlamydomonas reinhardtii
Ulva spp.
Monostroma spp.
Brown algae
Laminaria spp.
Sargassum spp.
Macrocystis pyrifera
Lessonia spp.
biomass from transgenics for animal health and feed; bioremediation,
environmental monitoring; production of recombinant proteins.
biomass for food and feed; extracts for cosmetics, wastewater
Treatment.
biomass for food; wastewater treatment.
alginate for food, pharmaceuticals, and cosmetics; biomass for food
and feed; wastewater treatment.
Wastewater treatment.
alginate for pharmaceuticals, cosmetics, food, and textile printing;
biomass for feed and fuel; wastewater treatment.
alginate for pharmaceuticals, cosmetics, food, and textile printing;
wastewater treatment.
Hallmann, (2007)
Cost parameter Conventional Effluent Treatment
Phycoremediation Annual cost benefit
Acidity -High levels of dissolved carbon dioxide
caustic soda Algal treatment Rs. 50 lakhs spent for caustic soda annually is saved (100%).
Sludge formation About 290 tonnes of sludge produced annually from this treatment.
There is no residual sludge.
The sludge disposal cost Rs. 3 lakhs annually. This cost is saved.
Structures and space.
11,000 Sq Mtrs of masonry tank for evaporating the effluent
3000 sq mtrs of tank for containing and evaporating the effluent.
About 75% of the effluent treatment facility space is released.
http://phycospectrum.com/moresnap.html
Phycoremediation is a multi-faceted effluent treatment 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
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