Jānis Vilgerts

Full Factorial Design of Screening Experiments for Biosurfactant Enhanced Remediation of Hydrophobic Substances in Soil

This paper evaluates the cleaning efficiency of glycolipid-based anionic biosurfactant produced by a local company. Before practical application in removal of oil or other hydrophobic substances from soil, it is necessary to learn the behavior of the biosurfactant across different systems. As process variables, temperature of environment, contact time with dilution of biosurfactant, and concentration of biosurfactant in washing solution were modeled by applying full factorial design. As response variable, cleaning efficiency was obtained experimentally by a set of laboratory tests. Screening design is employed for evaluation of interactions between response variable and process variables. The cleaning efficiency showed various results depending on the initial values of variables. At the upper limit of variables (+ 35 oC temperature of environment, 15 minutes contact time with dilution of biosurfactant, and 0.3 wt% concentration of biosurfactant in washing solution) the cleaning efficiency was 99.32 %. The results showed that all variables had significant effects on the cleaning efficiency at 95 % confidence level.

A methodology for forecasting hazardous waste flows

In previous years, great attention has been paid to the problem of hazardous waste management. “Prevention costs” of the activities concerned with hazardous waste (HW) are lower than “restoration costs” after damage is done. Within the scope of the paper the methodology for forecasting hazardous waste flows was elaborated. The methodology of the research included 6 modules: historical data, assumptions, choose of indicators, data processing, and data analysis with STATGRAPHICS, and forecast models. The proposed methodology was validated for the case for Latvia. A new type of the indicator based on the HW intensity within the Statistical Classification of Economic Activities in the European Community (NACE Rev. 2) sectors and households has been developed. The indicator allows for assessing the HW production intensity. The results of the study suggest that HW intensity in Latvia is forecasted to slowly decrease by 3.8% in next six years. The pessimistic prognosis (upper 95%) gives an increase in HW intensity by 44.5%, but the intermediate (upper and lower 50%) gives a corridor of +18.4% to –36.1%.