EFFECTS OF WATER-SOLUBLE FRACTION OF SPENT AND UNSPENT ENGINE OIL ON FRESHWATER MICROALGAE (Scenedesmus ecornis and Chlorella vulgaris)
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Abstract
This study was carried out to investigate the effects of the water-soluble fractions of spent and
unspent engine oil on two microalgae, Chlorella vulgaris and Scenedesmus ecornis. The test algae
were exposed to varying concentrations (0%, 5%, 10%, 25%, 50%, 75% and 100%) which were
set up in triplicates. The growth response was monitored every two days for 14 days using a visible
spectrophotometer (Model No. HV-721). The percentage inhibition, dry weight and analysis of
variance (ANOVA) were calculated using Microsoft Excel software. Physicochemical parameters
such as pH, electrical conductivity and total dissolved solids were measured using the appropriate method. The results revealed that growth of both microalgae decreased progressively with increasing concentration, with spent engine oil exhibiting greater toxicity than unspent engine oil. Growth rate analysis consistently favored Chlorella vulgaris in both engine oil. Statistical analysis using ANOVA indicated that it was significant (p< 0.0001) in growth response among the various concentrations for both species. The dry weight analysis revealed that in spent engine oil, the highest cumulative dry weights occurred in the control (391.23 mg/L for Scenedesmus ecornis and 394.24mg/L for Chlorella vulgaris), with marked reduction at 75-100%, with both species recording their lowest biomass at 100% (104.13 mg/L for Scenedesmus ecornis and 117.97 mg/L for Chlorella vulgaris) while in unspent engine oil, dry weight remained relatively high at 5-10% Percentage inhibition analysis revealed growth stimulation at low concentrations (5-10%), particularly in Scenedesmus ecornis exposed to unspent engine oil. In spent engine oil, Scenedesmus ecornis exhibited higher sensitivity than Chlorella vulgaris, while in unspent engine oil, Chlorella vulgaris exhibited greater sensitivity. The total dissolved solids, electrical conductivity, and pH decreased significantly across all concentrations. Spent engine oil is more toxic to microalgae than unspent oil, and the result indicates that Chlorella vulgaris is more suited for bioremediation of aquatic environments contaminated with unspent engine oil, while Scenedesmus ecornis show stronger potential for the bioremediation of water bodies polluted with spent engine oil.
unspent engine oil on two microalgae, Chlorella vulgaris and Scenedesmus ecornis. The test algae
were exposed to varying concentrations (0%, 5%, 10%, 25%, 50%, 75% and 100%) which were
set up in triplicates. The growth response was monitored every two days for 14 days using a visible
spectrophotometer (Model No. HV-721). The percentage inhibition, dry weight and analysis of
variance (ANOVA) were calculated using Microsoft Excel software. Physicochemical parameters
such as pH, electrical conductivity and total dissolved solids were measured using the appropriate method. The results revealed that growth of both microalgae decreased progressively with increasing concentration, with spent engine oil exhibiting greater toxicity than unspent engine oil. Growth rate analysis consistently favored Chlorella vulgaris in both engine oil. Statistical analysis using ANOVA indicated that it was significant (p< 0.0001) in growth response among the various concentrations for both species. The dry weight analysis revealed that in spent engine oil, the highest cumulative dry weights occurred in the control (391.23 mg/L for Scenedesmus ecornis and 394.24mg/L for Chlorella vulgaris), with marked reduction at 75-100%, with both species recording their lowest biomass at 100% (104.13 mg/L for Scenedesmus ecornis and 117.97 mg/L for Chlorella vulgaris) while in unspent engine oil, dry weight remained relatively high at 5-10% Percentage inhibition analysis revealed growth stimulation at low concentrations (5-10%), particularly in Scenedesmus ecornis exposed to unspent engine oil. In spent engine oil, Scenedesmus ecornis exhibited higher sensitivity than Chlorella vulgaris, while in unspent engine oil, Chlorella vulgaris exhibited greater sensitivity. The total dissolved solids, electrical conductivity, and pH decreased significantly across all concentrations. Spent engine oil is more toxic to microalgae than unspent oil, and the result indicates that Chlorella vulgaris is more suited for bioremediation of aquatic environments contaminated with unspent engine oil, while Scenedesmus ecornis show stronger potential for the bioremediation of water bodies polluted with spent engine oil.
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