Evaluation of efficiency in using turbidity curtains to retain suspended solids carried out on a pilot scale

Abstract

ABSTRACT This study aims to stimulate debate on the behavior of geotextile blankets in retaining suspended solids and to offer subsidies for further research. By means of a simple and objective approach, the results of a pilot-scale experiment are presented, with the objective of suggesting the use of containment barriers as a simple and inexpensive technique for raw water pre-filtration. Due to the growing demand for treated water and a marked decrease in the quality of the water available for catchment, it becomes necessary to increase the dosage of chemicals used in the treatment. Consequently, this influences not only the costs but also the characteristics of the waste generated in the process, since the nature and quantity of the sludge depend, among other factors, on the turbidity and the dosage of coagulant chemicals. The experiment was carried out using an acrylic channel where two adequately spaced geotextile blanket barriers were positioned, with raw water from the Parshall flume being pumped into the channel and, after passing through the barriers, returned by gravity to the flume and then sent for treatment. The affluent flow was maintained at 3.5 L/min and the blankets used had a weight of 170.0 and 420.0 g/m2, respectively. The results were not sufficient to conclude whether or not there is a relationship between the average raw water turbidity and the average turbidity reduction by the system. However, they show good chances of reducing sludge generation in water treatment plants receiving raw water pre-filtered by the proposed system, even with the average turbidity reduction considered low.