Effect of particle size distribution on turbidity under various water quality levels during flocculation processes

The dynamic relationship between particle size distribution and water turbidity was characterized using online real-time monitoring devices to explore the impact of particle size distribution on water quality. Particle amount was proportional to water turbidity in the range of 0-40NTU, whereas the correlation was rather poor in the range of 40-100NTU. The number of particles smaller than 5μm (N_d<5) should be strictly monitored and controlled in water treatment works (WTWs) due to their complex behaviors. The fractal dimension of particles (d_pf) is well suited to characterize particle size distribution under different water turbidities. The first derivative of d_pf was firstly used to explain the relationship between d_pf and the percentage of N_d<5, and the turbidity and d_pf values could be used together to monitor the temporal evolution of the number of smaller particles. A new block method for analyzing flocculation processes was proposed based on the change in d_pf. The particle counting method was more sensitive to the evolution of particle size, which allowed a better understanding of the impact of particle size distribution on water turbidity.