Fig 1.
Size distribution of the sedimented soil material, determined by laser diffractometry.
Note: The soil was not submitted to chemical pre-treatment for disaggregation.
Table 1.
Salts used as coagulants during the experiment.
Fig 2.
Top: Concept of differences in turbidity being an indicator of progress in sedimentation. Bottom: glass cylinders with 4 ion application rates of Ca in the form of CaCl2 and an ion-less control, after 3 hours.
Fig 3.
Sedimentation results of four concentrations of MgCl2 solutions, and a control using only distilled water.
Exponential curves were fitted using the Origin 6.0 software; curve parameters are presented in Table 2.
Table 2.
Curve parameters for the four concentrations of MgCl2 solutions.
Fig 4.
pH of the suspension upon start of the experiment (i.e. after mixing the soil and applied salts) vs. the change in pH after 3 hours.
Fig 5.
Overall efficiency of sedimentation after 3 hours, using the cation-anion pairs introduced in Table 1.
Fig 6.
Half-times of overall sedimentation–defined as the time required to achieve 50% of the expected final sedimentation efficiency, using an exponential model fitted to the data—using the cation-anion pairs introduced in Table 1 as coagulants.
Table 3.
Chloride and sulphate effects on the sedimentation efficiency (%): three repetitions and their averages (mean) with the standard deviation (SD).