Date of Award

2018

Degree Type

Thesis

Degree Name

Master of Science in Civil and Environmental Engineering

Department

Civil and Environmental Engineering

First Advisor

Vinka Oyanedel Craver

Abstract

The use of ceramic water filters (CWFs) is common in many households in developing and rural communities worldwide. Currently, CWFs are a viable means of microbial contaminant removal from untreated drinking water sources, however, very little is known about their ability to remove other organic and inorganic contaminants, such as heavy metals and hydrocarbons. CWFs are also commonly impregnated with silver nanoparticle to increase antimicrobial properties. However, little is known about the effect of the surface functionalization of silver nanoparticles on the performance of ceramic water filters. Furthermore, CWFs are typically used as a household water treatment system, in the form of a large pot filter. The feasibility of CWFs as a portable, point-of-use system will be examined in this thesis.

The main objective of this research was to assess the implications and effects of the surface functionalization of silver nanoparticles on the performance of CWF in terms of organic and inorganic contaminant removal. Ceramic disks were manufactured, characterized and tested under laboratory and field conditions to determine the address the aforementioned knowledge gaps. We used silver nanoparticles functionalized with casein, maltose and phyto-extracts to study the effects of microbiological, organic and inorganic contaminant removal using disks

manufactured in the laboratory. CWFs were functionalized with three nanoparticles synthesized using casein, maltose, and a extract from the rosemary plant as reducing agents, and were compared to unmodified CWFs manufactured from Red Art Clay. The disks were tested for their efficacy to remove from water metal ions, polycyclic aromatic hydrocarbons (PAHs), and E. coli simultaneously. Results showed that removal of bacteria was highly dependent on the mass of silver retained in each disk after impregnation with the nanoparticles. Results suggested that silver nanoparticle (nAg) average size and size distribution were the controlling factors in ceramic disks performance in terms of both bacterial and lead removal efficiency. The nAg size and size distribution dictated the amount of nAg retained within the ceramic disks after treatment, where smaller average size and more monodisperse nanoparticles (in this case, the Maltose nanoparticles and Rosemary nanoparticles) were preferentially retained within the disks, whereas larger, and polydisperse nAg particles (Casein nanoparticles) were released after the impregnation process. Hydrocarbon removal was unaffected by the mass of silver retained within the filters, and appeared to be removed by size exclusion, and retention in dead-end pores of the disks. Furthermore the removal rate of lead through the CWFs increased when the filters were treated with the silver nanoparticle, with Casein nanoparticles being the most effective amendment of the three nanoparticles tested.

Laboratory and field trials conducted in the Soweto province of South Africa, in which a point-of-use water treatment system called the CleanSip bottle was tested in conjunction with the CWFs. Two environmental samples were run through the system. The bottle exhibited log removal values (LRV) of up to 3.87 and proved effective at removing microbial pollutants from surface water bodies. Rosemary-nAg functionalized CWFs performed better than any of the other CWFs in terms of bacterial removal performance.

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