Influence of Operating Parameters on the Collection Efficiency and Size Distribution of Street Dust during Street Scrubbing

This study investigated the influence of operating parameters on the efficiency of collection of street dust using a street scrubber. Street scrubbing tests were performed in a full-scale, street scrubbing testing field, and on roads. The full-scale testing field was 40 m long and 1.95 m wide, specifically designed and constructed for this study. It was operated semi-automatically. The operating parameters investigated included nozzle type, street dust load, scrubbing speed, water injection loading, water injection pressure, distance above the ground, and water injection angle. Two types of nozzle, flat fan and hollow cone, were selected in the field tests. Four levels of street dust loading (level A: 0.39±0.28 g/m 2 , level B: 2.98±1.34 g/m 2 , level C: 8.02±2.08 g/m 2 , level D: 17.15±4.77 g/m 2 ) were used. The experimental results showed that, during scrubbing, the efficiency of collection of street dust decreased as street dust loading, scrubbing speed and distance above the ground increased, but increased with water injection loading and pressure. The determined optimal operating parameters were a scrubbing speed of less than 15 km/hr, a water injection loading of 0.8 L/m 2 , a water injection pressure of 2.0 kg/m 2 , distance above the ground of 30 cm and a water injection angle of 45 o . Additionally, the efficiency of collection of fine particles was higher than that of coarse particles. A multiple regression model was developed to predict the collection efficiency of street dust, based on experimental results obtained from street scrubbing field tests. The results suggested that street scrubbing should be able to reduce the fugitive emissions of street dust from paved roads.