Abstract

Effects of the untreated olive mill wastewater (UOMW) and the bioaugmented olive mill wastewater (BOMW) with the fungus Phanerochaete chrysosporium (P. chrysosporium) for the amendment of soil were investigated. Results showed that UOMW inhibited the soil respirometric activity, while BOMW exhibited significantly higher respiration levels compared to the unamended and the UOMW amended soils. The ratio of C-CO₂/C_tot decreased from 6.7 in the unamended soil to 6.34, to 2.74 and to 1.6 in soils amended consecutively with 50, 100 and 200 m³ ha^-1 of UOMW. Based on the first results, the UOMW dose of 50 m³ ha^-1 showed the elevated C-CO₂/C_tot ratio in comparison with the two other doses (100 and 200 m³ ha^-1) so that it was chosen to test the effects of its bioaugmentation with P. chrysosporium on the soil biodegradation activities. The fungus P. chrysosporium was added at three different forms; spores suspension (10⁶ spores g^-1), mycelium form (cultivated in liquid medium) and colony form (mycelium fragments from solid medium).The soil amended with 50 m³ ha^-1 of BOMW showed higher C-CO₂/C_tot ratio in comparison with control soil (unamended) and with soil amended with 50 m³ ha^-1 of UOMW. The C-CO₂/C_tot ratio increased from 6.34 in the soil amended by 50 m³ ha^-1 of UOMW and 6.7 in the control soil to 27 (nearly 4 fold) in soil amended by BOMW with the spores of P. chrysosporium, to 18.3 (nearly 2.7 fold) in soil amended by BOMW with P. chrysosporium at mycelium form and to 17.5 (nearly 2.6 fold) in soil amended by BOMW with P. chrysosporium at colony form. These investigations illustrated that the quantity of 50 m³ ha^-1 of olive mill wastewater bioaugmented byP. chrysosporium at spores form is very advantageous choice for the stimulation of the respirometric activities of soil autochthonous microflora.

Key words: olive mill wastewater; bioaugmentation; Phanerochaete chrysosporium; soil; respirometric activities.