Reducing turbidity of construction site runoff via coagulation with polyacrylamide and chitosan

dc.creatorRounce, David Robert
dc.creatorLawler, Desmond F.
dc.creatorBarrett, Michael E.
dc.date.accessioned2013-03-15T20:48:25Z
dc.date.accessioned2013-11-12T23:35:35Z
dc.date.available2013-03-15T20:48:25Z
dc.date.available2013-11-12T23:35:35Z
dc.date.created2012-08
dc.date.issued2013-03-15
dc.description.abstractThe U.S. Environmental Protection Agency is in the process of developing a nationwide standard for turbidity in construction site runoff. It is widely expected that this standard cannot be met with conventional erosion and sediment control measures; consequently, innovative practices for managing sediment on construction sites must be developed. The objective of this research was to develop an understanding of how soil characteristics and polymer properties affect the amount of turbidity reduction that can be achieved through flocculation. The polymers used were PAMs, a proprietary product, and chitosan. The charge density of the PAMs ranged from 0% to 50% and the molecular weights ranged from 0.2 to 14 Mg/mol. A protocol for creating modified synthetic stormwater runoff for soil samples was developed and used on soils from seven construction sites. Particle size distributions were used to compare the modified synthetic stormwater runoff with grab samples of stormwater from one site and showed the synthetic runoff was representative of the actual runoff. Flocculation tests were performed on the synthetic runoffs with PAM and chitosan doses from 0.03 to 10 mg/L. The non-ionic PAM, proprietary product, and chitosan were found to be the most effective at reducing the turbidity of all the synthetic runoff below 200 NTU. The high molecular weight anionic PAMs were effective on only two of the seven synthetic runoff samples. Hardness tests were performed indicating interparticle bridging to be the bonding mechanism of the PAM. Electrophoretic mobility tests were performed on two of the soil suspensions and indicated the bonding mechanism of PAM to be interparticle bridging, and the bonding mechanism of chitosan to be a combination of charge neutralization and interparticle bridging. Tests showed as the charge density of the PAM increased, their effectiveness decreased.en_US
dc.description.departmentResearch in Water Resources, Center foren_US
dc.identifier.urihttp://hdl.handle.net/2152/19750
dc.language.isoengen_US
dc.publisherCenter for Research in Water Resources, University of Texas at Austinen_US
dc.relation.ispartofseriesCRWR online report;2012-02
dc.subjectturbidityen_US
dc.subjectconstruction site runoffen_US
dc.subjectpolyacrylamideen_US
dc.subjectchitosanen_US
dc.subjectPAMsen_US
dc.subjectflocculationen_US
dc.titleReducing turbidity of construction site runoff via coagulation with polyacrylamide and chitosanen_US
dc.typeTechnical Reporten_US

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