Changes of catalytic mass grains morphology as a result of their surface covering with iron compounds

Maciej Dobrzański,Andrzej Jodłowski

doi:10.1051/e3sconf/20185900029

Abstract

There were operational problems of not having the ability to remove manganese compounds in one of the country's groundwater treatment plants, despite the fact that the filters were some years earlier fitted with the Multiman 3M catalytic bed inserts. The paper presents the results of analysis of morphological characteristics of fresh and blocked catalytic grains. An equivalent diameter, circularity, convexity, and compactness were used to describe the morphological characteristics of the catalytic mass grains. The obtained results confirmed the assumption that the grains of the catalytic mass were blocked by iron hydroxide and that the cause of WTP operating problems was the failure of the aerator, which resulted in the penetration of iron hydroxide through the upper sand bed layer into the lower catalytic mass layer.

Highlights

Groundwater is one of the main sources of tap water, especially in rural areas
This paper presents the results of evaluation of the morphological characteristics of catalytic grains collected in a small rural WTP treating underground water, where the removal efficiency of manganese and iron was lost
Measurements and analysis of equivalent diameters and morphological parameters of catalytic mass grains were carried out using Malvern Morphologi G3 microscope image analyzer

Summary

Introduction

The principal problem of groundwater treatment is usually the need of excessive concentrations of iron and manganese ions removal. Removal of Fe (II) and Mn (II) ions from water is usually achieved by oxidizing them to insoluble forms, which are removed in the single- or two-stage filtration process through single or multi-layer beds. The iron removal process is relatively simple, usually involving the use of aeration, followed by filtration through a bed of quartz sand to retain the iron hydroxide precipitated from the water. Oxidation of manganese in the catalyst bed is effective only after primary removing excess of iron from the water. The iron hydroxide can be precipitated and retained in the catalytic layer, which significantly reduces the manganese removal efficiency [2,3]

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Conclusion