Development of a novel polysilicate ferric coagulant and its application to coagulation-membrane filtration hybrid system in wastewater treatment

Nejad, Firoozeh Nateghi Ghasemian

Development of a novel polysilicate ferric coagulant and its application to coagulation-membrane filtration hybrid system in wastewater treatment

Nejad, Firoozeh Nateghi Ghasemian

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Publication Type:: Thesis
Issue Date:: 2014

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Field	Value	Language
dc.contributor.author	Nejad, Firoozeh Nateghi Ghasemian
dc.date.accessioned	2014-12-01T07:40:29Z
dc.date.available	2014-12-01T07:40:29Z
dc.date.issued	2014
dc.identifier.uri	http://hdl.handle.net/10453/30352
dc.description	University of Technology, Sydney. Faculty of Engineering and Information Technology.	en_US
dc.description.abstract	Coagulation is one of the effective pretreatment stages in membrane filtration of wastewater to produce clean water. Using a suitable coagulant can mitigate membrane fouling. Membrane fouling is a process where solute or particles deposit onto a membrane surface or into membrane pores in a way that degrades the membrane performance. Research in this area is currently being focused on development of improved coagulation reagents such as polysilicate ferric (PSiFe), which has a high molecular weight and large number of positive surface charges with high efficiency at low doses. In this thesis, PSiFe has prepared based on the following approaches: (a) acidification of water glass solution using HCl followed by FeCl₃ addition and (b) acidification of water glass solution by passing it through an acidic ion exchange resin followed by fresh FeCl₃ addition under different Fe/Si molar ratios. These coagulants were characterised by X-ray diffraction and scanning electron microscopy. According to coagulation jar test results, when Fe/Si=1 the best performance was achieved in terms of the turbidity, the total organic carbon (TOC) and UV₂₅₄ removals. In this study, a thorough experimental program has been carried out to compare the performance of three different coagulants including the existing PSiFe, FeCl₃ and the modified PSiFe. The results clearly indicated that in a membrane filtration system using the modified PSiFe not only reduces the required transmembrane pressure (TMP) due to lower fouling, but also improves the TOC removal efficiency. The outcome of this research provides an efficient coagulant, which can create a sustainable coagulation-membrane filtration system with a lower consumption of chemicals compared to traditional coagulants, and lower fouling that consequently leads to minimum operating and maintenance costs. The findings of this research have also revealed that the performance of the target coagulant, PSiFe-γ, is superior to conventional reagents. Hence, this coagulant and the developed procedure in this study can be used in industry to enhance the coagulation process for achieving a more effective wastewater treatment procedure.	en_US
dc.format	Thesis (PhD)	en_US
dc.language.iso	en	en_US
dc.relation	https://opus.lib.uts.edu.au/bitstream/10453/30352/2/02whole.pdf
dc.rights	info:eu-repo/semantics/openAccess
dc.rights	The author owns the copyright in this thesis including all reproduction and reuse rights for the work. The work may not be altered without the permission of the copyright owner. Attribution is essential when quoting or paraphrasing from this thesis.
dc.rights	au.edu.uts.lib/ppc
dc.subject	Wastewater treatment.	en
dc.subject	Polysilicate ferric.	en
dc.subject	Coagulation.	en
dc.subject	Membrane fouling.	en
dc.subject	Membrane filtration.	en
dc.subject	Transmembrane pressure.	en
dc.title	Development of a novel polysilicate ferric coagulant and its application to coagulation-membrane filtration hybrid system in wastewater treatment	en_US
dc.type	Thesis
utslib.copyright.status	open_access

Abstract:

Coagulation is one of the effective pretreatment stages in membrane filtration of wastewater to produce clean water. Using a suitable coagulant can mitigate membrane fouling. Membrane fouling is a process where solute or particles deposit onto a membrane surface or into membrane pores in a way that degrades the membrane performance. Research in this area is currently being focused on development of improved coagulation reagents such as polysilicate ferric (PSiFe), which has a high molecular weight and large number of positive surface charges with high efficiency at low doses. In this thesis, PSiFe has prepared based on the following approaches: (a) acidification of water glass solution using HCl followed by FeCl₃ addition and (b) acidification of water glass solution by passing it through an acidic ion exchange resin followed by fresh FeCl₃ addition under different Fe/Si molar ratios. These coagulants were characterised by X-ray diffraction and scanning electron microscopy. According to coagulation jar test results, when Fe/Si=1 the best performance was achieved in terms of the turbidity, the total organic carbon (TOC) and UV₂₅₄ removals. In this study, a thorough experimental program has been carried out to compare the performance of three different coagulants including the existing PSiFe, FeCl₃ and the modified PSiFe. The results clearly indicated that in a membrane filtration system using the modified PSiFe not only reduces the required transmembrane pressure (TMP) due to lower fouling, but also improves the TOC removal efficiency. The outcome of this research provides an efficient coagulant, which can create a sustainable coagulation-membrane filtration system with a lower consumption of chemicals compared to traditional coagulants, and lower fouling that consequently leads to minimum operating and maintenance costs. The findings of this research have also revealed that the performance of the target coagulant, PSiFe-γ, is superior to conventional reagents. Hence, this coagulant and the developed procedure in this study can be used in industry to enhance the coagulation process for achieving a more effective wastewater treatment procedure.

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