Cleanup of water polluted with crude oil or diesel fuel using rice husks ash

Abstract

The sources of contamination of fresh and seawater are most often spills of oil and oil products by accidents with tankers or underwater pipes, as well as offshore oil platforms and oil refineries. Moreover the ships produce a large amount of oily wastewater such as bilge water which needs to be treated prior to being discharged. The bilge water is a difficult wastewater to treat as it contains seawater, particulates, used oils and detergents. Micro- and ultrafiltration are often the methods of choice to treat this water. The pretreatment of this oily wastewater prior to ultrafiltration is desirable, as the used oils and particulates can block the feed channels of the ultrafilters spiral and hollow fiber modules. In this reason, at the last time different hybrid adsorbents with high adsorption capacity and appropriate porous structure are used. The present study is an attempt to establish the possibilities to obtain black rice husk ash (BRHA) and white rice husks ash (WRHA) via pyrolysis of raw rice husks in a pilot plant fluidized-bed reactor at different conditions. The products obtained are characterized using X-ray diffraction patterns, scanning electron microscopy, FT-IR spectroscopy, thermal analysis, and low temperature nitrogen adsorption. Using batch adsorption technique, the kinetics was studied and the adsorption capacities of crude oil and diesel fuel at different temperatures as well as some hydrocarbons at 298 K onto BRHA and WRHA are determined. It was established that BRHA have been higher adsorption capacity than WRHA. At a given temperature, BRHA sorbed more crude oil than diesel fuel. The results obtained showed that the material studied has high adsorption capacity and low cost and may successfully be used as an effective adsorbent to cleanup of bilge water and spills of oil and oil products in water basins. Because the saturated BRHA with crude oil, diesel fuel or different hydrocarbons are characterized with high calorific, they can be burnt in incinerators, industrial ovens or steam generators. By this way we attain not only ecological but also economical effect.