Date of Award

Fall 2016

Project Type

Thesis

Program or Major

Civil Engineering

Degree Name

Master of Science

First Advisor

James P Malley

Second Advisor

Jumeng Zheng

Third Advisor

Weiwei Mo

Abstract

Manganese is an important drinking water constituent and is often linked to aesthetic and operational problems. The increasing use of membrane filtration in drinking water treatment also shines a spotlight on emerging new processes such as ceramic microfiltration. This research provides a better understanding of how manganese contributes to ceramic membrane fouling through surface chemistry. Research was performed at PWN Technologies (PWNT) in Andijk, The Netherlands on the site of the full-scale Andijk III water treatment facility, which uses ceramic microfilters. Laboratory analysis indicates some transition metals such as manganese and iron are adsorbed by the ceramic membrane. The adsorption of these inorganics during ceramic microfiltration could cause hydraulically irreversible fouling requiring removal through chemically enhanced backwashing (EBW). In practice, this is performed with a low pH EBW (pH 2) in combination with hydrogen peroxide (100 ppm). The purpose of this study was to gain a better understanding of the interaction between manganese and the ceramic membrane, as well as to develop methods for manganese fouling control.

Jar tests using synthetic manganese solutions, activated alumina (AA) powders, and nanostructured ceramic materials (Al2O3 and TiO2 powders) were used to mimic surface interactions that take place during ceramic microfiltration. The impacts of surrounding pH, peroxide concentration, dissolved organic concentration (DOC), and powder types on the manganese adsorption were studied. The jar tests showed that the high pH led to more manganese adsorption; DOC, in most cases, inhibited manganese adsorption; and peroxide pre- treatment did not show noticeable differences on the manganese adsorption. Powder properties, especially charge properties, had a notable impact on the manganese adsorption, with more negatively charged powder adsorbing more positively charged manganese. The “desorption” experiments were organized into two groups: desorption of the fresh adsorbed manganese and desorption of the “aged” manganese. For the fresh adsorbed manganese, DOC inhibited the desorption, while differing peroxide concentrations and low pHs showed no noticeable difference. With the “aged” adsorbed manganese, the powder type had a more significant effect, and the low pH and peroxide concentrations altered desorption significantly.

Pilot studies evaluated different EBW methods for fouling control, namely evaluating single sodium hypochlorite EBW, single low pH/peroxide EBW, consecutive sodium hypochlorite – low pH/peroxide EBWs, and consecutive low pH/peroxide – sodium hypochlorite EBWs. Results showed the consecutive sodium hypochlorite – low pH/peroxide EBWs yielded the best operation. The sodium hypochlorite EBW removed the organic fouling. Once organics were removed, the manganese could be more efficiently removed by the low pH/peroxide EBW.

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