Microbial stimulating potential of Pineapple peel (Ananas comosus) and Coconut (Cocos nucifera) husk char in crude-oil polluted soil

Abstract

The bioremediation potential of ten different treatments formed from two organic sources of nutrients: coconut husk ash (CHA) and pineapple peel (PP) on 5kg of soil polluted with 400ml of crude oil were monitored for 84 days. The changes in the physicochemical properties of the soil were observed, the degradation process was monitored by; the measure of the total petroleum hydrocarbon (TPH) loss, the total bacterial and fungal counts, the crude oil utilizing bacterial and fungal counts. The result revealed that there was a reduction in the soil TPH with all treatments and also the polluted control, which may be owing to natural attenuation. The treatment, PP12 was seen to have the lowest TPH value of 40.40 ± 0.40 mg/kg at the 84th day with a percentage reduction of 89.90. This was followed by the PP8 (49.733±0.267mg/kg) and PP4 (70.000±0.577mg/kg), also the POC (polluted control) had a concentration of 245.333±1.453mg/kg at the 84th day which is a 38.67% reduction. The treatment, CHA12 influenced the TPH to a concentration of 78.000±1.528mg/kg which was an 80% reduction. The total bacterial count had the highest CFU/g of 2.06 x 107 ± 0.006 on the soil treated with CHAPP12 and the least count was at POC (2.3 x 106± 0.007cfu/g). Crude oil utilizing bacteria were least with the POC (0.21 x 104 ± 0.010 CFU/g) and were more at the PP12 treated soil (1.3 x 105 ± 0.012). Some of the probable bacterial isolates identified through biochemical testing included Bacillus spp., Serratia spp., Proteus spp., Pseudomonas spp., Enterobacter spp., Klebsiella spp., Aeromonas spp.and Staphylococci spp. The fungi isolates ranged from 3.0 x 104 CFU/g to 6.0 x 104CFU/g and identified fungi included Cephalosporiumspp, Coccidioides immitis, Aspergillus niger, Aspergillus fumigatus, Penicillium spp, Trichophyton mentagrophyte, and Moraxella spp.