🧪 Investigating the Impact of Particle Size Distribution on Water Turbidity During Flocculation and Sedimentation 🚰📅 Particle size dist...
Published on by Hossein Ataei Far, Deputy Manager of the Research, Technology Development, and Industry Relations Center at NWWEC
📅 Particle size distribution (PSD) on water turbidity during flocculation and sedimentation processes
🔬 The study investigates the impact of particle size distribution (PSD) on water turbidity during flocculation and sedimentation processes using kaolin clay suspensions. It aims to understand how different stirring conditions influence particle aggregation and subsequently affect water quality assessment through turbidity measurements.
Particle size ranges were used in this study. The size ranges were expressed as various channels (i.e. CH1–CH5) in the particle counter
Channel: CH1 CH2 CH3 CH4 CH5
Size range (µm) 2–3 3–5 5–15 15–25 >25
Summary of Findings:
PSD Evolution During Flocculation:
🔹Flocculation causes small particles to aggregate into larger ones over time.
🔹Stirring speeds of 50, 90, and 150 rpm showed varying effects:
🔹At 50 rpm: Significant aggregation observed initially, with steady-state reached later.
🔹At 90 and 150 rpm: More pronounced particle breakage due to higher shear rates, impacting aggregation dynamics.
Impact of PSD on Water Turbidity:
🔹Turbidity measurements were sensitive to particle size:
🔹Turbidity < 25 NTU: Dominated by small particles (< 5 µm).
🔹Turbidity 30–60 NTU: Increased presence of larger particles.
🔹Turbidity > 60 NTU: Larger particles (> 5 µm) dominate.
🔹Strong linear correlation between turbidity and larger particles (> 5 µm), but poor correlation with smaller particles (< 5 µm).
Practical Implications:
🔹Optimal Stirring Conditions: Stirring speeds between 50 to 90 rpm were found optimal for reducing small particle counts (Nd 90 rpm) led to increased particle breakage and poorer water quality.
🔹Combining Turbidity and Particle Counting: Effective in evaluating water treatment efficiency and safety, emphasizing the importance of monitoring Nd