Summer 2009 CDC Research

Overview

Abstract

One of the most recent problems AguaClara plants have encountered has been the formation of foam at the beginning of the flocculator. In order to figure out what chemical condition is required for this foam development a rapid mix chamber and flocculator were modeled using jar mixers, an aerator and gallon size plastic tanks. The first test trials were conducted with a constant supply of clay and varying amounts of alum but these did not exhibit any form of foam formation. Subsequent trials included organic matter: humic acid but these only produced weak, temporary foam. It was not until liquid soap, a surfactant, was added to the mixing that a persistent, firm foam developed in the first baffle spacing. From these experiments it was concluded that air entrainment, along with dead organic matter in the raw water were the main factors behind the foam formation. As a result, the most current research is focused on retrofitting AguaClara's designs so that no air entrainment occurs in the entrance tank and rapid mix chamber.

Introduction and Objectives

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