Study On The Treatment Of Oil Contaminated Wastewater By Soil Aquifer Treatment System

Soil aquifer treatment(SAT)is a geographical purification system,which is progressively adopted as a useful secondary dependable means of enhancing water resources and cutting down indiscriminate discharge of treated wastewater into water bodies.The purpose of this study was to establish a soil aquifer treatment system for the removal of diesel pollutants in wastewater.A 90 cm long PVC column with an internal diameter of 5cm was used to simulate the soil column used in the SAT system.Aquifer material of less than 2.00 mm was used to have homogeneous soil column fill material,reduce flow distortions,minimize unrepresentative effects of earthworms and debris and use grain sizes that contribute to expulsion in the SAT procedure.Loess soil was used in the soil column as the aquifer.The columns were operated in 1-week cycle consisting of 3 days of wetting followed by 4 days of drying(3w/4d)for a total of 4 cycles.The study explains the effect of variation of temperature of preliminary treated wastewater from 30 ℃ to 45 ℃ on the system performance.Process efficiencies for BOD and COD removal were as high as 99.12% and 92.53% respectively.At higher temperatures and at cycle 4,less COD and BOD were present in the effluent to mean that there was higher removal rates of the latter at higher temperatures.There was also significant removal of diesel oil from the effluent collected from the experiment with cycle 4 having the highest removal efficiency of diesel oil at 88%.The study also focused on isolation,morphological and biochemical characterization of bacteria possessing hydrocarbon degrading properties.The study also aimed at optimizing appropriate culture conditions for the isolates as well as screening for diesel oil degradation capabilities.5 bacteria strains were identified as following;Enterococcus faecalis-L1,Lysiniibacillus-L2,Bacillus sp-L3,Rhodococcus equi-L4 and Ochrobactrum-L5.Based on their ability to degrade diesel oil,two isolates were selected and their growth conditions optimized.Optimum bacteria growth was recorded at 2% substrate(diesel)concentration,pH 7-8 and temperature range of between 25℃ and 30℃ for the bacteria strains L2 and L4.