Dewatering of oily slurry using drying bed with geotextile filter

A new proposal for treatment of oily slurry is presented in this paper. The proposed technique consists of using drying beds with geotextile filters for water content and volume reduction of the slurry. Owing to the high concentration of contaminants, the disposal of this slurry may potentially be an environmentally hazardous practice. Hence techniques for dewatering pretreatment were developed, aiming at reducing the quantity of waste before disposal in landfills, land farms or incineration. Dewatering of the slurry may lead to reduced environmental impact and reduced cost for transport and disposal. Laboratory tests were performed for technical evaluation of the efficiency of the proposed procedure. Column tests were carried out using four types of filter: two nonwoven geotextiles and one woven geotextile, and a sand filter for performance comparison. Prototype tests were also performed, and results are included in this paper. No matter which filter type was used, the test results show good retention filter capacity and satisfactory drainage capacity. The process of dewatering the slurry brought considerable reduction in its water content and volume, minimising the volume of the final waste to be discharged. After dehydration, the treated slurry shows a tenfold concentration increase in oil and grease content, which contributes to its high calorific value. Hence the dehydrated slurry may be used as an alternative source of energy.