Jānis Vilgerts’s research while affiliated with Riga Technical University and other places

he scope of our research is to outline dynamics of the transition from informal to formal waste collection system, where the influence of social, economic and policy factors are modelled. The case study is based on lead-acid accumulator's collection system in Latvia. The developed model is valid as decision supporting system for policy developers and as a platform for scientists for further research on dynamics of informal waste management practices. The model can be extended for other boundaries.

The scope of our research is to outline dynamics of the transition from informal to formal waste collection system, where the influence of social, economic and policy factors are modelled. The case study is based on lead-acid accumulator's collection system in Latvia. The developed model is valid as decision supporting system for policy developers and as a platform for scientists for further research on dynamics of informal waste management practices. The model can be extended for other boundaries.

Much research in recent years has been done on sustainable hazardous waste management system, nevertheless the amounts of hazardous waste generated increases. The major share of these hazardous substances is a product of activities within NACE sectors. By now there are few studies trying to bring the problem of waste elimination down to the level of a single enterprise. This paper proposes the methodology for assessment of changes for the aggregate of hazardous waste flow at enterprise level due to relative impact of investigated factors, such as hazardous waste intensity, material intensity and the amount of raw material consumed in enterprise. The use of derivatives from IPAT and Kaya identities together with logarithmic mean Divisia index decomposition analysis is presented. Based on the proposed methodology case studies at enterprise level can be done in order to explore a cause in the aggregate changes in the past, present the forecast model for future trends, and also identify leverage points for intervention of policy tools with the aim to reduce the amount of hazardous waste. This research is the first attempt to link together government initiatives and hazardous waste flow at enterprise level based on quantitative indices.

Although the field of waste batteries and accumulators (B&A) recently has attracted lots of attention from general public and policy makers and the number of researches conducted with the application of system dynamic modelling has a wide application for waste management sector, there is still a lack of research regarding the complexity of problems within the waste B&A management. Thus in this paper the dynamic model for the management system of waste B&A has been studied. The model is applied for the case study of Latvia. The developed SD model allows the investigation of complex relations and simulation of effects from various policies within the management system of waste B&A, because the model incorporates non-linearities, feedbacks and delays. The results of sensitivity analysis show that the changes in the collection ratio and import rate have both high and at the same time in the opposite direction aimed influence on the amount of landfilled B&A. This paper shows that the introduction of innovation diffusion model for the sector of waste batteries and accumulators can decrease environmental pollution by up to 30.7 %. However, based on the developed system dynamic model, scenarios comprising other policies could also be simulated, evaluated and discussed.

The scope of this research is to perform bioremediation of historically polluted, multiple fraction soil with glycolipid-based anionic biosurfactants. The aim is to optimize the conditions for ex situ soil washing by involving statistical data analysis tools for experimental data. The quadratic interaction model shows that the most influential process parameter at a 95.0 % confidence level was observed for the biosurfactant concentration variable. The results of the study proved the potential for applications of “plate” tests for the formulation of new soil washing products and for the selection of proper biosurfactants for the problem under study.

A proper management strategy for hazardous waste is one of key components for a sustainable development. The quantity of various flows for hazardous waste should be identified before a precise management strategy for hazardous waste can be developed. Until now there is not one unique way how countries within the European Union should report on the yearly amount of hazardous waste. Within the scope of the paper the methodology for quantification of hazardous waste flows was elaborated. The proposed methodology was applied for the case study of the Baltic States: Estonia, Latvia and Lithuania. Objectives for the paper included: analysis of statistical data on amount of hazardous waste in the Baltic States, identification of statistically significant independent variables, which describe the hazardous waste flows at 95 % confidence level, combination of statistical data analysis with evaluation of main indicators in order to propose the methodology for quantification of hazardous waste flows. The multiple regression analysis was carried out in order to identify the strength of correlation between amount of hazardous waste and defined independent variables. The equation includes 5 statistically significant independent variables. The equation can be used for the forecasts of amount of hazardous waste in the Baltic States. The proposed methodology for the quantification of hazardous waste flows is based on unique solution, which combines study of main indicators with the use of multiple regression equation.

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

The objective of the paper is to develop the forecast model for the HW flows. 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 study for Latvia. Hypothesis on the changes in HW for time period of 2010-2020 have been developed and mathematically described with confidence level of 95.0 % and 50.0 %. Sensitivity analysis for the analyzed scenarios was done. The results show that the growth of GDP affects the total amount of HW in the country. The total amount of the HW is projected to be within the corridor of – 27.7 % in the optimistic scenario up to +87.8 % in the pessimistic scenario with confidence level of 50.0 % for period of 2010-2020. The optimistic scenario has shown to be the least flexible to the changes in the GDP growth.

During past years a great attention is 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 the 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 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 year. The pessimistic prognosis (upper 95 %) gives an increase in HW intensity by 44.5 %, but intermediate (upper and lower 50 %) gives a corridor of + 18.4 % to – 36.1 %.

In this paper the dynamic model for the composting of contaminated soils with petroleum products is presented. The main objectives of this study is to gain a deeper understanding about the dynamic relations between composting process and demand in the market and to determine how different policies will influence the model and therefore the total amount of recycled contaminated soil. The methodology applied consists of system dynamic model, which describes the relationships between a cause and effect in complex and dynamic systems that have delays, feedbacks and non-linearities. The developed model passed both the behaviour validity and the tests of behavioural sensitivity. The validation indicated that the model is capable of generating ‘the right behaviour for the right reasons’. This paper shows the results of four various policies (including reference scenario) and sensitivity analysis. The results of the research indicate that the most sensitive parameter is the volume available for composting, which is the main factor that influences the amount of recycled material.