title: Strength of natural soil flocs.
abstract: To obtain the strength of flocs against breakup is crucial for controlling flocculation in water treatment and predicting transport of colloidal particles in aqueous environments. Recently, the author reported a method to obtain floc strength from a simple experiment of floc breakup subjected to a laminar converging flow. In this study, this method was applied to natural soil flocs. The flocs were formed by coagulation with 0.5 M NaCl (pH 5.4-5.5, pH 6.6) solutions, 0.1M CaCl2 (pH 6.4-6.9) solutions, or acidified distilled water with dilute HCl (pH 5.6). Obtained floc strengths were 0.3, 0.7 and 4 nN for Na-, Ca-, and H-coagulated flocs, respectively. Also, floc strength did not change with floc size. These values of floc strengths were 1-3 orders smaller than those of flocs formed with polymer flocculants and/or precipitated ferric or aluminum coagulants.
authors: Laboratory of Water Environmental Engineering, Department of Biological and Environmental Engineering, University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113-8657, Japan. mkoba@iwate-u.ac.jp
authors: Motoyoshi
authors: M
authors: Kobayashi
mesh_terms: D017607:Aluminum Compounds / Q000737:chemistry; D002122:Calcium Chloride / Q000737:chemistry; D011232:Chemical Precipitation; D003102:Colloids / Q000737:chemistry*; D005290:Ferric Compounds / Q000737:chemistry; D005427:Flocculation; D006851:Hydrochloric Acid / Q000737:chemistry; D010316:Particle Size; D012965:Sodium Chloride / Q000737:chemistry; D012987:Soil; D014865:Waste Disposal, Fluid / Q000379:methods*; D014871:Water Microbiology; D014874:Water Pollutants, Chemical; D018508:Water Purification / Q000379:methods*
chemical_list: D017607:Aluminum Compounds; D003102:Colloids; D005290:Ferric Compounds; D012987:Soil; D014874:Water Pollutants, Chemical; D012965:Sodium Chloride; D002122:Calcium Chloride; D006851:Hydrochloric Acid