Treatment of oil mill wastewaters by infiltration-percolation on two types of filters based on soil,sand and fly ash

The olive oil extraction industry generates high amount of olive mill solid waste and olive mill wastewater. these effluents are heavily loaded with organic matter. although they are rich in nutrients for plants,their discharges without any treatment affect the quality of water and soil and cause immense environmental damages. the objective of this study is the treatment of oil mill wastewaters of the city of sefrou (morocco) by infiltration-percolation on two types of filters. the first based on soil and sand (f1) and the second based on soil,sand and fly ash (f2). the results of the physicochemical analyses show that oil mill wastewaters have an acidic ph (4.48) and are a very high organic matter concentration (cod 329.68 g/l and bod5 of 20 g/l),suspended matter (5.7 g/l) and dissolved salts (13.18 ms/cm). the total polyphenol is 1.28 g/l. their levels of trace metals are low except for iron where its content reached 78.17 mg/l. the treatment of oil mill wastewaters by both f1 and f2 filters has allowed an increase in the ph which becomes basic,a decrease in electrical conductivity,a significant removal of cod,bod5,total polyphenols,mes,nitrogenous materials,phosphate pollutants of elements analyzed and significant reductions of trace metals,respectively in f1 and f2. however,a release of the calcium element is observed at filter 2.