Bioremediation of diesel contaminated soils : an investigation into the effects of biosurfactant and organic matter amendments

The aim of this study was to investigate the effects of biosurfactants and organic matter amendments on the bioremediation of diesel contaminated soil. Two strains of Pseudomonas aeruginosa with the ability to produce biosurfactant were isolated from a water and soil sample in Co. Sligo. The first strain, Isolate A, produced a biosurfactant which contained four rhamnose containing compounds, when grown in proteose peptone glucose ammonium salts medium with glucose as the carbon source. Two of the components were identified as rhamnolipid 1 and 2 whilst the other two components were unidentified. The second strain, Isolate GO, when grown in similar conditions produced a biosurfactant which contained only rhamnolipid 2. The type of aeration system used had a significant effect on the abiotic removal of diesel from soil. Forced aeration at a rate of 120L 02/kg soil/ hour resulted in the greatest removal. Over a 112 day incubation period this type o f aeration resulted in the removal o f 48% o f total hexane extractable material. In relation to bioremediation of the diesel contaminated sandy soil, amending the soil with two inorganic nutrients, KH2PO4 and NÜ4N03, significantly enhanced the removal of diesel, especially the «- alkanes, when compared to an unamended control. The biosurfactant from Isolate A and a biosurfactant produced by Pseudomonas aeruginosa NCIMB 8628 (a known biosurfactant producer), when applied at a concentration of three times their critical micelle concentration, had a neutral effect on the biodégradation o f diesel contaminated sandy soil, even in the presence o f inorganic nutrients. It was deduced that the main reason for this neutral effect was because they were both readily biodegraded by the indigenous microorganisms. The most significant removal of diesel occurred when the soils were amended with two organic materials plus the inorganic nutrients. Amendment of the diesel contaminated soil with spent brewery grain (SBG) removed significantly more diesel than amendment with dried molassed sugar beet pulp (DMSBP). After a 108 day incubation period, amendment of the diesel contaminated soil with DMSBP plus inorganic nutrients and SBG plus inorganic nutrients resulted in 72 and 89% removal of diesel range organics (DRO), in comparison to 41% removal of DRO in an inorganic nutrient amended control. The first order kinetic model described the degradation of the different diesel components with high correlation and was used to calculate Vi lives. The V2 life, of the total «-alkanes in the diesel was reduced from 40 days in the control to 8.5 and 5.1 days in the presence of DMSBP and SBG, respectively. The V2 life o f the unresolved complex mixture (UCM) in the diesel contaminated soil was also significantly reduced in the presence o f the two organics. DMSBP and SBG addition reduced UCM V2 life to 86 and 43 days, respectively, compared to 153 days in the control. The component of diesel whose removal was enhanced the greatest through the organic material amendments was the isoprenoid, pristane, a compound which until recently was thought to be nonbiodegradable and was used as an inert biomarker in oil degradation studies. The V2 life of pristane was reduced from 533 days in the nutrient amended control to 49.5 and 19.5 days in DMSBP and SBG amended soils. These results indicate that the addition o f the DMSBP and SBG to diesel contaminated soil stimulated diesel biodégradation, probably by enhancing the indigenous diesel degrading microbial population to degrade diesel hydrocarbons, whilst the addition o f biosurfactants had no enhanced effect on the bioremediation process.

Does the provision of full day care improve the quality of life for children and their parents

This study sought to explore and examine if the provision of full day care improves the quality of life for children and their parents. Owing to the effects of the Celtic Tiger, life in Ireland has changed considerably over the past five to ten years. Because of the booming economy there are now 60.8% of women employed in the workforce. This means many changes for children, parents and families. Findings in the literature review are based on international studies. The researcher utilised both qualitative and quantitative research methodologies for the study. She interviewed 31 respondents; 27 childcare managers; 3 politicians and the chairperson of a childcare committee. Furthermore, 325 questionnaires were completed in a survey by working parents in the statutory and voluntary sectors in and around Sligo town and in two childcare facilities in Letterkenny, Co. Donegal. Babies as young as 4 months are being cared for in childcare facilities from 6.45am until 6.pm daily, 5 days per week. Some children are spending up to 11 hours per day in childcare facilities. The study has not categorically concluded that full day care is either positive or negative for children. Childcare facilities are providing good quality childcare encompassing various services; however, 25 out of 27 childcare managers reported to the researcher that they would not leave their child in full day care. Parents are finding it difficult to manage work life balance. Health dominated quality of life issues. Two hundred and thirty five (235) parents reported being stressed. The study also found that 315 working parents feel that the government is not doing enough to support working parents. On a positive note, 241 parents said they are happy in general with the quality of life for them, their family and their children. In addition, the researcher has identified a number of recommendations for future changes in policy and further study.