Microbiological and Physicochemical Characteristics of Soil Receiving Palm Oil Mill Effluent in Umuahia, Abia State, Nigeria

Abstract

The microbiological and physicochemical characteristics of soil receiving palm oil mill effluent (POME) in Umuahia were investigated. A total of 20 samples were analyzed for total heterotrophic bacterial count, fungal count, hydrocarbon-utilizing bacterial count, hydrocarbon-utilizing fungal count and nitrifying bacterial count. The pour plate technique was used for the isolation of the organisms. The mean total heterotrophic bacterial count ranged from 6.00 ± 0.07Log₁₀cfu/g to 6.13 ± 0.06Log₁₀cfu/g while the effluent and control soil sample were 5.80 ± 0.05Log₁₀cfu/mL and 6.19 ± 0.04Log₁₀cfu/g respectively. The fungal mean count ranged from 3.53 ± 0.02Log₁₀cfu/g to 4.03 ± 0.01Log₁₀cfu/g for contaminated soil and 3.69 ± 0.01Log₁₀cfu/mL for effluent. The mean count for the hydrocarbon-utilizing bacteria ranged from 5.34 ± 0.3Log₁₀cfu/g to 5.96 ± 0.2Log₁₀cfu/g for soil and 5.77 ± 0.06Log₁₀cfu/mL for effluent. Hydrocarbon-utilizing fungal count for the soil ranged from 2.95 ± 0.1Log₁₀cfu/g to 3.23 ± 0.01Log₁₀cfu/g and 3.00 ± 0.00Logcfu/mL for the effluent. The mean count for nitrifying bacteria ranged from 2.90 ± 0.2Log₁₀cfu/g to 3.42 ± 0.1Log₁₀cfu/g for soil and 4.38 ± 0.2Log₁₀cfu/mL for effluent. Results of the physicochemical analysis showed that the pH recorded for contaminated soil and control was 6.1 and 5.5 respectively and 7.2 for the effluent. The mean values for conductivity, oil and grease, phosphate, nitrate, sulphate, calcium, sodium, potassium, magnesium, in contaminated soil were 63.8 ± 5.0?s/cm, 8.1 ± 0.6mg/kg, 3.84 ± 0.1%, 1.50 ± 0.05mg/kg, 0.59 ± 0.01mg/kg, 27 ± 3.0mg/kg, 219 ± 15.0mg/kg, 116 ± 10.0mg/kg, 6.0 ± 0.5mg/kg, 0.85 ± 0.02mg/kg respectively. The mean values for conductivity, oil and grease, phosphate, nitrate, sulphate, calcium, sodium, potassium, magnesium, for the control soil were 46.7 ± 6.0?s/cm, 1.0 ± 0.04mg/kg, 0.93 ± 0.02%, 0.62 ± 0.01mg/kg, 0.33 ± 0.01mg/kg, 13.0 ± 2.0mg/kg,156 ± 10.0mg/kg, 83 ± 4.0mg/kg, 3 ± 0.6mg/kg, 0.52 ± 0.03mg/kg. The mean values of the conductivity, oil and grease, turbidity, chloride, dissolved oxygen, biochemical oxygen demand, chemical oxygen demand, total suspended solids, total dissolved solids, ammonia, phosphate, nitrate and sulphate for the raw effluent were 26.5 ± 3.0?s/cm, 12.3 ± 2.0, 55.0 ± 3.0NTU, 10 ± 1.0mg/L, 1.8 ± 0.2mg/L, 25 ± 2.0mg/L, 60 ± 4.0mg/L, 32 ± 1.0mg/L, 0.35 ± 0.02mg/L, 0.40 ± 0.01mg/L, 0.21 ± 0.01mg/kg, 0.55 ± 0.02mg/kg, 2.0 ± 0.3mg/kg respectively. The results shows that the POME impacts on the soil

Key words: Microbiological, physicochemical, characteristics, soil, palm oil, mill, effluent