Greywater Treatment by High Rate Algal Pond under Sahelian Conditions for Reuse in Irrigation
Author(s)
Ynoussa Maiga1*,
Masahiro Takahashi2,
Thimotée Yirbour Kpangnane Somda3,
Amadou Hama Maiga3
Affiliation(s)
1 Laboratory of Microbiology and Microbial Biotechnology, University of Ouagadougou, Ouagadougou, Burkina Faso. 2 Environmental Engineering and Science, Hokkaido University, Sapporo-shi, Japan. 3 Laboratory of Water Decontamination, Ecosystems and Health, International Institute for Water and Environmental Engineering, Ouagadougou, Burkina Faso.
1 Laboratory of Microbiology and Microbial Biotechnology, University of Ouagadougou, Ouagadougou, Burkina Faso. 2 Environmental Engineering and Science, Hokkaido University, Sapporo-shi, Japan. 3 Laboratory of Water Decontamination, Ecosystems and Health, International Institute for Water and Environmental Engineering, Ouagadougou, Burkina Faso.
ABSTRACT
High Rate Algal Pond (HRAP) was constructed and operated using a mixer device to investigate its capability in treating greywater for reuse in gardening. Physico-chemical and microbiological parameters were monitored. With a hydraulic retention time of 7.5 days and a solid retention time of 20 days, the average removal efficiencies (ARE) were 69% and 62% for BOD5 and COD respectively. The ARE for
, 
and 
were 23%, 52% and 43% respectively. The removal of suspended solids (SS) was unsatisfactory, which could be attributed to the low average algal settling efficiencies of 9.3% and 16.0% achieved after 30 and 60 minutes respectively. The ARE of fecal coliforms, Escherichia coli and enterococci were 2.65, 3.14 and 3.17 log units respectively. In view of the results, the HRAP technology could be adapted for greywater treatment in sahelian regions. However, further studies on the diversity of the algal species growing in the HRAP unit are necessary in order to increase the removal of SS. Hazards of a reuse of the effluents are discussed on the basis of the various qualitative parameters. The residual content of E. coli was varying from <1 to 1.77 × 104 CFU per 100 mL. Based on WHO guidelines for greywater reuse in irrigation, the effluents could be used for restricted irrigation (E. coli < 105 CFU per 100 mL). Furthermore, the reuse potential is discussed on the basis of FAO guidelines using SAR (3.03 to 4.11), electrical conductivity (482 to 4500 μS/cm) and pH values (6.45 to 8.6).
High Rate Algal Pond (HRAP) was constructed and operated using a mixer device to investigate its capability in treating greywater for reuse in gardening. Physico-chemical and microbiological parameters were monitored. With a hydraulic retention time of 7.5 days and a solid retention time of 20 days, the average removal efficiencies (ARE) were 69% and 62% for BOD5 and COD respectively. The ARE for
, and were 23%, 52% and 43% respectively. The removal of suspended solids (SS) was unsatisfactory, which could be attributed to the low average algal settling efficiencies of 9.3% and 16.0% achieved after 30 and 60 minutes respectively. The ARE of fecal coliforms, Escherichia coli and enterococci were 2.65, 3.14 and 3.17 log units respectively. In view of the results, the HRAP technology could be adapted for greywater treatment in sahelian regions. However, further studies on the diversity of the algal species growing in the HRAP unit are necessary in order to increase the removal of SS. Hazards of a reuse of the effluents are discussed on the basis of the various qualitative parameters. The residual content of E. coli was varying from <1 to 1.77 × 104 CFU per 100 mL. Based on WHO guidelines for greywater reuse in irrigation, the effluents could be used for restricted irrigation (E. coli < 105 CFU per 100 mL). Furthermore, the reuse potential is discussed on the basis of FAO guidelines using SAR (3.03 to 4.11), electrical conductivity (482 to 4500 μS/cm) and pH values (6.45 to 8.6).
Cite this paper
Maiga, Y. , Takahashi, M. , Somda, T. and Maiga, A. (2015) Greywater Treatment by High Rate Algal Pond under Sahelian Conditions for Reuse in Irrigation. Journal of Water Resource and Protection, 7, 1143-1155. doi: 10.4236/jwarp.2015.714094.
Maiga, Y. , Takahashi, M. , Somda, T. and Maiga, A. (2015) Greywater Treatment by High Rate Algal Pond under Sahelian Conditions for Reuse in Irrigation. Journal of Water Resource and Protection, 7, 1143-1155. doi: 10.4236/jwarp.2015.714094.
References
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http://vertigo.revues.org/10312 [3] Friedle, R.E. and Hadari, M. (2006) Economic Feasibility of On-Site Greywater Reuse in Multi-Storey Building. Desalination, 190, 221-234.
http://gwri.technion.ac.il/pdf/gwri_abstracts/2006/57.pdf
http://dx.doi.org/10.1016/j.desal.2005.10.007 [4] Winward, G.P., Avery, L.M., Frazer-Williams, R., Pidou, M., Jeffrey, P., Stephenson, T. and Jefferson, B. (2008) A Study of the Microbial Quality of Greywater and an Evaluation of Treatment Technologies for Reuse. Ecological Engineering, 32, 187-197.
http://www.sciencedirect.com/science/article/pii/S092585740700211X
http://dx.doi.org/10.1016/j.ecoleng.2007.11.001 [5] Tarchitzky, J., Lerner, O., Shani, U., Arye, G., Lowengart-Aycicegi, A., Brener, A. and Chen, Y. (2007) Water Distribution Pattern in Treated Wastewater Irrigated Soils: Hydrophobicity Effect. European Journal of Soil Science, 58, 573-588.
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http://www.sciencedirect.com/science/article/pii/S0048969710002524
http://dx.doi.org/10.1016/j.scitotenv.2010.03.005 [7] Park, J.B.K. and Craggs, R.J. (2010) Wastewater Treatment and Algal Production in High Rate Algal Ponds with Carbon Dioxide Addition. Water Science and Technology, 63, 633-639.
http://www.ncbi.nlm.nih.gov/pubmed/20150699
http://dx.doi.org/10.2166/wst.2010.951 [8] Craggs, R.J., Heubeck, S., Lundquist, T.J. and Benemann, J.R. (2011) Algae Biofuel from Wastewater Treatment High Rate Algal Ponds. Water Science and Technology, 63, 660-665.
http://www.ncbi.nlm.nih.gov/pubmed/21330711
http://dx.doi.org/10.2166/wst.2011.100 [9] Sukias, J.P.S. and Craggs, R.J. (2011) Digestion of Wastewater Pond Microalgae and Inhibition from Ammonium and Alum. Water Science and Technology, 63, 835-840.
http://www.ncbi.nlm.nih.gov/pubmed/21411930
http://dx.doi.org/10.2166/wst.2011.101 [10] Nacir, S., Ouazzani, N., Vasel, J.L., Jupsin, H. and Mandi, L. (2010) Traitement des eaux usées domestiques par un chénal algal à haut rendement (CAHR) agité par air lift sous climat semi-aride. Revue des sciences de l’eau/Journal of Water Science, 23, 57-72.
http://www.erudit.org/revue/rseau/2010/v23/n1/038925ar.html?vue=resume [11] Park, J.B.K., Craggs, R.J. and Shilton, A.N. (2011) Wastewater Treatment High Rate Algal Ponds for Biofuel Production. Bioresource Technology, 102, 35-42.
http://www.sciencedirect.com/science/article/pii/S0960852410011636
http://dx.doi.org/10.1016/j.biortech.2010.06.158 [12] Kenfack, S. (2006) Helio-Photocatalytic Enhancement of the Biodegradation of Biorecalcitrant Pollutants in Water: Physicochemical and Technical Aspects. PhD Thesis, EPFL, Lausanne. [13] American Public Health Association (APHA), American Water Works Association (AWWA) and Water Environment Federation (WEF) (1998) Standard Methods for the Examination of Water and Wastewater. 20th Edition, APHA/ AWWA/WEF, Washington DC. [14] Park, J.B.K., Craggs, R.J. and Shilton, A.N. (2011) Recycling Algae to Improve Species Control and Harvest Efficiency from a High Rate Algal Pond. Water Research, 45, 6637-6648.
http://www.sciencedirect.com/science/article/pii/S0043135411005720 [15] Maiga, Y., Moyenga, D., Ushijima, K., Sou, M. and Maiga, A.H. (2014) Greywater Characteristics in Rural Areas of Sahelian Region for Reuse Purposes: The Case of Burkina Faso. Revue des sciences de l’eau/Journal of Water Science, 27, 39-54.
www.erudit.org/revue/rseau/2014/v27/n1/1021981ar.html?vue=resume&modes=restriction. [16] Morel, A. and Diener, S. (2006) Greywater Management in Low and Middle-Income Countries, Review of Different Treatment Systems for Households and Neighborhood. Swiss Federal Institute of Aquatic Science and Technology (Eawag), SANDEC, Dübendorf. [17] Aguirre, P., Alvarez, E., Ferrer, I. and Garcia, J. (2011) Treatment of Piggery Wastewater in Experimental High Rate Algal Ponds. Revista Latinoamericana de Biotecnologia Ambiental y Algal, 2, 57-66.
http://uniciencia.ambientalex.info/revistas/vol2n21.pdf [18] Santiago, A.N., Calijuri, M.L., Assemany, P.P., Calijuri, M.C. and dos Reis, A.J.D. (2013) Algal Biomass Production and Wastewater Treatment in High Rate Algal Ponds Receiving Disinfected Effluent. Environmental Technology, 34, 1877-1885.
http://dx.doi.org/10.1080/09593330.2013.812670 [19] Picot, B., Moersidik, S., Casellas, C. and Bontoux, J. (1993) Using Diurnal Variations in a High Rate Algal Pond for Management Pattern. Water Science and Technology, 28, 169-175.
http://www.iwaponline.com/wst/02810/wst028100169.htm [20] Chen, P., Zhou, Q., Paing, J., Le, H. and Picot, B. (2003) Nutrient Removal by the Integrated Use of High Rate Algal Ponds and Macrophyte Systems in China. Water Science and Technology, 48, 251-257.
http://www.ncbi.nlm.nih.gov/pubmed/14510218 [21] El Hamouri, B., Rami, A. and Vasel, J.L. (2003) The Reasons behind the Performance Superiority of a High Rate Algal Pond over Three Facultative Ponds in Series. Water Science and Technology, 48, 269-276.
http://www.ncbi.nlm.nih.gov/pubmed/14510220. [22] Derabe, H.M., Onodera, M., Takahashi, M., Satoh, H. and Fukazawa, T. (2014) Control of Algal Production in a High Rate Algal Pond: Investigation through Batch and Continuous Experiments. Water Science and Technology, 69, 2519-2525.
http://www.ncbi.nlm.nih.gov/pubmed/24960016
http://dx.doi.org/10.2166/wst.2014.174 [23] García, J., Mujeriego, R. and Hernández-Mariné, M. (2000) High Rate Algal Ponds Operating Strategies for Urban Wastewater Nitrogen Removal. Journal of Applied Phycology, 12, 331-339.
http://link.springer.com/article/10.1023%2FA%3A1008146421368
http://dx.doi.org/10.1023/A:1008146421368 [24] Maiga, Y., Moyenga, D., Nikiema, B.C., Ushijima, K., Maiga, A.H. and Funamizu, N. (2014) Designing Slanted Soil System for Greywater Treatment for Irrigation Purposes in Rural Area of Arid Regions. Environmental Technology, 35, 3020-3027.
http://dx.doi.org/10.1080/09593330.2014.929180
http://dx.doi.org/10.1080/09593330.2014.929180 [25] Arana, I., Irizar, A., Seco, C., Muela, A., Fernández-Astorga, A. and Barcina, I. (2003) gfp-Tagged Cells as a Useful Tool to Study the Survival of Escherichia coli in the Presence of the River Microbial Community. Microbial Ecology, 45, 29-38.
http://www.ncbi.nlm.nih.gov/pubmed/12447583
http://dx.doi.org/10.1007/s00248-002-1029-9 [26] Benchokroun, S., Imziln, B. and Hassani, L. (2003) Solar Inactivation of Mesophilic Aeromonas by Exogenous Photooxidation in High-Rate Algal Pond Treating Wastewater. Journal of Applied Microbiology, 94, 531-538.
http://www.ncbi.nlm.nih.gov/pubmed/12588563
http://dx.doi.org/10.1046/j.1365-2672.2003.01867.x [27] Maiga, Y., Wethe, J., Denyigba, K. and Ouattara, A.S. (2009) The Impact of Pond Depth and Environmental Conditions on Sunlight Inactivation of E. coli and Enterococci in Wastewater in a Warm Climate. Canadian Journal of Microbiology, 55, 1364-1374.
http://www.ncbi.nlm.nih.gov/pubmed/20029528
http://dx.doi.org/10.1139/W09-104 [28] Muela, A., Garcia-Bringas, J.M., Seco, C., Arana, I. and Barcina, I. (2002) Participation of Oxygen and Role of Exogenous and Endogenous Sensitizers in the Photoinactivation of Escherichia coli by Photosynthetically Active Radiation, UV-A and UV-B. Microbial Ecology, 44, 354-364.
http://www.ncbi.nlm.nih.gov/pubmed/12375094
http://dx.doi.org/10.1007/s00248-002-1027-y [29] Anderson, K.L., Whitlock, J.E. and Harwood, V.J. (2005) Persistence and Differential Survival of Fecal Bacteria in Subtropical Waters and Sediments. Applied and Environmental Microbiology, 71, 3041-3048.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1151827/pdf/1861-04.pdf
http://dx.doi.org/10.1128/AEM.71.6.3041-3048.2005 [30] Jori, G. and Brown, S.B. (2004) Photosensitized Inactivation of Microorganisms. Photochemical & Photobiological Sciences, 3, 403-405.
http://www.ncbi.nlm.nih.gov/pubmed/15122355
http://dx.doi.org/10.1039/b311904c [31] Baya, D.G.S.T. (2012) Etude de l’autofloculation dans un chénal algal à haut rendement. Thèse de Doctorat, Université de Liège, Liège. (In French) [32] WHO (2006) Guidelines for the Safe Use of Wastewater, Excreta and Greywater, Volume 4: Excreta and Greywater Use in Agriculture. WHO Press, Geneva. [33] Mara, D. (2004) Domestic Wastewater Treatment in Developing Countries. Earthscan, London. [34] Grattan, S.R. (2002) Irrigation Water Salinity and Crop Production. Publication 8066, University of California, Oakland.
http://vric.ucdavis.edu/pdf/Irrigation/IrrigationWaterSalinityandCropProduction.pdf [35] Food and Agriculture Organization of the United Nations (1985) Water quality for agriculture. FAO, Rome.
http://www.fao.org/DOCReP/003/T0234e/T0234e00.htm
[1] International Water Management Institute (IWMI) (2010) Wastewater Irrigation and Health: Assessing and Mitigating Risk in Low-Income Countries. Earthscan, London. [2] Kêdowidé, C.M.G., Sedogo, M.P. and Cissé, G. (2010) Dynamique spatio temporelle de l’agriculture urbaine à Ouaga-dougou: Cas du Maraîchage comme une activité montante de stratégie de survie. Vertigo—La Revue Electronique en Sciences de l’Environnement, 10, [En Ligne].
http://vertigo.revues.org/10312 [3] Friedle, R.E. and Hadari, M. (2006) Economic Feasibility of On-Site Greywater Reuse in Multi-Storey Building. Desalination, 190, 221-234.
http://gwri.technion.ac.il/pdf/gwri_abstracts/2006/57.pdf
http://dx.doi.org/10.1016/j.desal.2005.10.007 [4] Winward, G.P., Avery, L.M., Frazer-Williams, R., Pidou, M., Jeffrey, P., Stephenson, T. and Jefferson, B. (2008) A Study of the Microbial Quality of Greywater and an Evaluation of Treatment Technologies for Reuse. Ecological Engineering, 32, 187-197.
http://www.sciencedirect.com/science/article/pii/S092585740700211X
http://dx.doi.org/10.1016/j.ecoleng.2007.11.001 [5] Tarchitzky, J., Lerner, O., Shani, U., Arye, G., Lowengart-Aycicegi, A., Brener, A. and Chen, Y. (2007) Water Distribution Pattern in Treated Wastewater Irrigated Soils: Hydrophobicity Effect. European Journal of Soil Science, 58, 573-588.
http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2389.2006.00845.x/abstract
http://dx.doi.org/10.1111/j.1365-2389.2006.00845.x [6] Travis, M.J., Wiel-Shafran, A., Weisbrod, N., Adar, E. and Gross, A. (2010) Greywater Reuse for Irrigation: Effect on Soil Properties. Science of the Total Environment, 408, 2501-2508.
http://www.sciencedirect.com/science/article/pii/S0048969710002524
http://dx.doi.org/10.1016/j.scitotenv.2010.03.005 [7] Park, J.B.K. and Craggs, R.J. (2010) Wastewater Treatment and Algal Production in High Rate Algal Ponds with Carbon Dioxide Addition. Water Science and Technology, 63, 633-639.
http://www.ncbi.nlm.nih.gov/pubmed/20150699
http://dx.doi.org/10.2166/wst.2010.951 [8] Craggs, R.J., Heubeck, S., Lundquist, T.J. and Benemann, J.R. (2011) Algae Biofuel from Wastewater Treatment High Rate Algal Ponds. Water Science and Technology, 63, 660-665.
http://www.ncbi.nlm.nih.gov/pubmed/21330711
http://dx.doi.org/10.2166/wst.2011.100 [9] Sukias, J.P.S. and Craggs, R.J. (2011) Digestion of Wastewater Pond Microalgae and Inhibition from Ammonium and Alum. Water Science and Technology, 63, 835-840.
http://www.ncbi.nlm.nih.gov/pubmed/21411930
http://dx.doi.org/10.2166/wst.2011.101 [10] Nacir, S., Ouazzani, N., Vasel, J.L., Jupsin, H. and Mandi, L. (2010) Traitement des eaux usées domestiques par un chénal algal à haut rendement (CAHR) agité par air lift sous climat semi-aride. Revue des sciences de l’eau/Journal of Water Science, 23, 57-72.
http://www.erudit.org/revue/rseau/2010/v23/n1/038925ar.html?vue=resume [11] Park, J.B.K., Craggs, R.J. and Shilton, A.N. (2011) Wastewater Treatment High Rate Algal Ponds for Biofuel Production. Bioresource Technology, 102, 35-42.
http://www.sciencedirect.com/science/article/pii/S0960852410011636
http://dx.doi.org/10.1016/j.biortech.2010.06.158 [12] Kenfack, S. (2006) Helio-Photocatalytic Enhancement of the Biodegradation of Biorecalcitrant Pollutants in Water: Physicochemical and Technical Aspects. PhD Thesis, EPFL, Lausanne. [13] American Public Health Association (APHA), American Water Works Association (AWWA) and Water Environment Federation (WEF) (1998) Standard Methods for the Examination of Water and Wastewater. 20th Edition, APHA/ AWWA/WEF, Washington DC. [14] Park, J.B.K., Craggs, R.J. and Shilton, A.N. (2011) Recycling Algae to Improve Species Control and Harvest Efficiency from a High Rate Algal Pond. Water Research, 45, 6637-6648.
http://www.sciencedirect.com/science/article/pii/S0043135411005720 [15] Maiga, Y., Moyenga, D., Ushijima, K., Sou, M. and Maiga, A.H. (2014) Greywater Characteristics in Rural Areas of Sahelian Region for Reuse Purposes: The Case of Burkina Faso. Revue des sciences de l’eau/Journal of Water Science, 27, 39-54.
www.erudit.org/revue/rseau/2014/v27/n1/1021981ar.html?vue=resume&modes=restriction. [16] Morel, A. and Diener, S. (2006) Greywater Management in Low and Middle-Income Countries, Review of Different Treatment Systems for Households and Neighborhood. Swiss Federal Institute of Aquatic Science and Technology (Eawag), SANDEC, Dübendorf. [17] Aguirre, P., Alvarez, E., Ferrer, I. and Garcia, J. (2011) Treatment of Piggery Wastewater in Experimental High Rate Algal Ponds. Revista Latinoamericana de Biotecnologia Ambiental y Algal, 2, 57-66.
http://uniciencia.ambientalex.info/revistas/vol2n21.pdf [18] Santiago, A.N., Calijuri, M.L., Assemany, P.P., Calijuri, M.C. and dos Reis, A.J.D. (2013) Algal Biomass Production and Wastewater Treatment in High Rate Algal Ponds Receiving Disinfected Effluent. Environmental Technology, 34, 1877-1885.
http://dx.doi.org/10.1080/09593330.2013.812670 [19] Picot, B., Moersidik, S., Casellas, C. and Bontoux, J. (1993) Using Diurnal Variations in a High Rate Algal Pond for Management Pattern. Water Science and Technology, 28, 169-175.
http://www.iwaponline.com/wst/02810/wst028100169.htm [20] Chen, P., Zhou, Q., Paing, J., Le, H. and Picot, B. (2003) Nutrient Removal by the Integrated Use of High Rate Algal Ponds and Macrophyte Systems in China. Water Science and Technology, 48, 251-257.
http://www.ncbi.nlm.nih.gov/pubmed/14510218 [21] El Hamouri, B., Rami, A. and Vasel, J.L. (2003) The Reasons behind the Performance Superiority of a High Rate Algal Pond over Three Facultative Ponds in Series. Water Science and Technology, 48, 269-276.
http://www.ncbi.nlm.nih.gov/pubmed/14510220. [22] Derabe, H.M., Onodera, M., Takahashi, M., Satoh, H. and Fukazawa, T. (2014) Control of Algal Production in a High Rate Algal Pond: Investigation through Batch and Continuous Experiments. Water Science and Technology, 69, 2519-2525.
http://www.ncbi.nlm.nih.gov/pubmed/24960016
http://dx.doi.org/10.2166/wst.2014.174 [23] García, J., Mujeriego, R. and Hernández-Mariné, M. (2000) High Rate Algal Ponds Operating Strategies for Urban Wastewater Nitrogen Removal. Journal of Applied Phycology, 12, 331-339.
http://link.springer.com/article/10.1023%2FA%3A1008146421368
http://dx.doi.org/10.1023/A:1008146421368 [24] Maiga, Y., Moyenga, D., Nikiema, B.C., Ushijima, K., Maiga, A.H. and Funamizu, N. (2014) Designing Slanted Soil System for Greywater Treatment for Irrigation Purposes in Rural Area of Arid Regions. Environmental Technology, 35, 3020-3027.
http://dx.doi.org/10.1080/09593330.2014.929180
http://dx.doi.org/10.1080/09593330.2014.929180 [25] Arana, I., Irizar, A., Seco, C., Muela, A., Fernández-Astorga, A. and Barcina, I. (2003) gfp-Tagged Cells as a Useful Tool to Study the Survival of Escherichia coli in the Presence of the River Microbial Community. Microbial Ecology, 45, 29-38.
http://www.ncbi.nlm.nih.gov/pubmed/12447583
http://dx.doi.org/10.1007/s00248-002-1029-9 [26] Benchokroun, S., Imziln, B. and Hassani, L. (2003) Solar Inactivation of Mesophilic Aeromonas by Exogenous Photooxidation in High-Rate Algal Pond Treating Wastewater. Journal of Applied Microbiology, 94, 531-538.
http://www.ncbi.nlm.nih.gov/pubmed/12588563
http://dx.doi.org/10.1046/j.1365-2672.2003.01867.x [27] Maiga, Y., Wethe, J., Denyigba, K. and Ouattara, A.S. (2009) The Impact of Pond Depth and Environmental Conditions on Sunlight Inactivation of E. coli and Enterococci in Wastewater in a Warm Climate. Canadian Journal of Microbiology, 55, 1364-1374.
http://www.ncbi.nlm.nih.gov/pubmed/20029528
http://dx.doi.org/10.1139/W09-104 [28] Muela, A., Garcia-Bringas, J.M., Seco, C., Arana, I. and Barcina, I. (2002) Participation of Oxygen and Role of Exogenous and Endogenous Sensitizers in the Photoinactivation of Escherichia coli by Photosynthetically Active Radiation, UV-A and UV-B. Microbial Ecology, 44, 354-364.
http://www.ncbi.nlm.nih.gov/pubmed/12375094
http://dx.doi.org/10.1007/s00248-002-1027-y [29] Anderson, K.L., Whitlock, J.E. and Harwood, V.J. (2005) Persistence and Differential Survival of Fecal Bacteria in Subtropical Waters and Sediments. Applied and Environmental Microbiology, 71, 3041-3048.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1151827/pdf/1861-04.pdf
http://dx.doi.org/10.1128/AEM.71.6.3041-3048.2005 [30] Jori, G. and Brown, S.B. (2004) Photosensitized Inactivation of Microorganisms. Photochemical & Photobiological Sciences, 3, 403-405.
http://www.ncbi.nlm.nih.gov/pubmed/15122355
http://dx.doi.org/10.1039/b311904c [31] Baya, D.G.S.T. (2012) Etude de l’autofloculation dans un chénal algal à haut rendement. Thèse de Doctorat, Université de Liège, Liège. (In French) [32] WHO (2006) Guidelines for the Safe Use of Wastewater, Excreta and Greywater, Volume 4: Excreta and Greywater Use in Agriculture. WHO Press, Geneva. [33] Mara, D. (2004) Domestic Wastewater Treatment in Developing Countries. Earthscan, London. [34] Grattan, S.R. (2002) Irrigation Water Salinity and Crop Production. Publication 8066, University of California, Oakland.
http://vric.ucdavis.edu/pdf/Irrigation/IrrigationWaterSalinityandCropProduction.pdf [35] Food and Agriculture Organization of the United Nations (1985) Water quality for agriculture. FAO, Rome.
http://www.fao.org/DOCReP/003/T0234e/T0234e00.htm