Mathematical modelling of waste flows and treatment based on reconstruction of historical data: Case of wastewater sludge in Czech Republic

Abstract

The contribution of supporting tools developed for logistic optimization and processing infrastructure planning is highly dependent on the quality of input data. Databases containing reports on waste production and treatment are often used for waste management case studies and in the aggregated form at the national level provide sufficient information with negligible errors. On the other hand, analysis in greater detail at the smallest administrative unit usually reveals significant inconsistencies, especially in the case of mass balance control. This often results in the impossibility to track waste flows in the system and evaluate final treatment. This paper aims to present a tool for database verification in order to satisfy mass balances at all levels of the investigated system. As part of the mathematical modelling, the database is first subjected to a statistical analysis where selected inconsistencies between records can be removed. Subsequently, data reconciliation is applied with appropriate weights assigned to each entity in the system. The weights represent credibility and reflect various errors, which are identified in the previous stage of the approach. The correction of mass balances enables an evaluation of quality or composition in greater detail of individual entities and also determines the feasible interval of monitored properties. The tool is applied to the treatment evaluation of dry matter in wastewater sludge in the Czech Republic. Thanks to the developed tool, disposal and material or energy recovery can be quantified at micro-regional.