Treatment of dredged materials using modified electro- Osmotic remediation method

Abstract

This projects aims to investigate a cost effective and efficient method to dewater dredged materials to allow for the subsequent reutilisation of these waste materials. Dredged materials are produced in large volumes annually due to shipping channel maintenance and new port development, and re-utilisation of these dredged materials will help to ease the strain on existing dumping facilities and provide an alternative source of fill materials. Although dredged materials contain large proportions of marine clay, the impurities, such as oils and metal contaminants, along with the sizable proportion of sand particles present have impeded the effective dewatering treatment via Electro-Osmosis (EO) method alone, as shown in the initial test series. Several innovative improvement schemes were investigated in this research. A new modified EO chamber was developed. The positive effect on the dewatering efficiency of dredged materials using the coupling of positive and negative pressures with the application of EO method was observed and further studied in this research. The test series suggested that the application of positive pressure during the early stages of coupled EO treatment had a positive effect towards the dewatering efficiency of dredged materials. The results also showed that the application of negative pressure aided in the drainage of water collection at the cathode, which in turn allowed for the full application of the positive pressure during the early stages of the treatment. The improved properties (i.e. increased undrained shear strength and improved compressibility parameters) of the treated dredged materials allow for the reutilization of these treated dredged materials. The advantages of this coupled EO treatment include shorter treatment times, high efficiency in energy consumption and the ability to treat contaminated soils.