Evaluation of beneficial of polyacrylamide use dewatering of dredged sludge obtained from golden horn

Abstract

This study proposes a methodology to prevent excessive and misuse of polymers in dewatering applications. In this study, to determine the optimum conditions some measurement were performed such as zeta potential measurements to arrange the pH of the slurry, flocculation tests to reduce turbidity and settlement time, particle size distribution analysis to enhance floc size, and Fourier-Transform Infrared Spectroscopy (FTIR) analysis to limit the level of trace elements that can be discharged into the sea. For the study area, Golden Horn located in Istanbul of which contaminated sea bottom sediments are dredged periodically was selected. 11 anionic and 2 cationic varieties of polyacrylamides were used considering the zeta potential observations on the slurries arranged at pH = 3–9. Anionic polymers performed better than cationic ones at the intended dosage. 30 ppm concentration of AA4 polymer enhanced the mean floc size D50= 0.06–0.12 mm, and increased the settlement rate up to 4.4 cm/min, so 121 NTU turbidity (99.7% yield) was achieved. The remaining water was polymer-free and was suitable for discharge to the marine environment. So, further investigations on polymer selection will be optimized dewatering process and lead to environmental sustainability and economic savings.