Design of a laboratory method for rapid evaluation of experimental flocculants

Authors: Garcia, Rafael; Riner, Stephanie; Piazza, George

Submitted to: Applied Engineering in Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/17/2013
Publication Date: 12/17/2013
Citation: Garcia, R.A., Riner, S.A., Piazza, G.J. 2013. Design of a laboratory method for rapid evaluation of experimental flocculants. Applied Engineering in Agriculture. 53(2):880-886.

Interpretive Summary: Flocculants are substances that help in removing particles from water. Flocculants are used, for example, in an early stage of sewage treatment; the dirty water has particles in it that are so small that they will not settle out for long time. A flocculant causes these particles to stick together and become bigger clumps which can settle quickly. Flocculants are also used in many other applications including agricultural irrigation, manufacturing and construction. Recently, many researchers have been developing and testing new flocculants, and a lot of the new flocculants are either synthetic polymers or substances made from biological material, including agricultural by-products. The methods they use to test the flocculants, however, are usually very poorly thought-out and produce data that are of limited utility. In this research, we took apart the testing method and examined each aspect of it carefully to learn how it could be improved. The result is a dramatically improved test method which should be of use to researchers and should help to speed progress in the development of new flocculants.

Technical Abstract: Reports of novel organic polymeric flocculants have become commonplace. The method used to test the effectiveness of these flocculants is most often the flocculation of a kaolin suspension in a jar test. The widely varying versions of this method that appear in the literature suffer from a range of weaknesses. The present research uses well-defined kaolin and confines testing to conditions in which the kaolin suspension is stable in the absence of a flocculant. The research examines all aspects of the conduct of the method, including clay dosing, mixing, settling time and measurement to improve the sensitivity, reproducibility and robustness of the method, and takes steps to avoid pitfalls that can reduce the validity of the method. Innovations include careful selection of the buffer system and instrument characteristics. Kaolin Flocculation Effectiveness is introduced as a metric that gives a meaningful indication of the relative value of a novel flocculant while emphasizing the critical importance of test conditions. Together, the results form a set of recommended test conditions that should be useful for most new flocculant research.