Strength of natural soil flocs.
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.
Kobayashi
Motoyoshi
M
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
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*
D017607:Aluminum Compounds; D003102:Colloids; D005290:Ferric Compounds; D012987:Soil; D014874:Water Pollutants, Chemical; D012965:Sodium Chloride; D002122:Calcium Chloride; D006851:Hydrochloric Acid