Post-consumer plastic sorting infrastructure improvements planning: Scenario-based modeling of greenhouse gas savings with sustainable costs.

With the increasing share of waste material recovery, household plastic waste is one of the biggest problems. In most countries, mainly manual sorting is used. Meanwhile, new automated technologies are being developed to expand the range of classifiable types to increase material recovery. The overall automation of the sorting process can help the EU's established recycling targets to be effectively met. However, the new technologies are feasible only in the case of large-capacity centers, which must be conveniently located in the existing infrastructure. This paper presents a two-stage model aiming to modernize the current sorting infrastructure for plastic waste. The approach uses multi-criteria optimization to minimize environmental impact at a reasonable price. The result is the optimal location of new automatic sorting centers, and waste stream flows using existing manual sorting facilities. The model is applied through an initial case study inspired by the Czech Republic data. Optimization output proposes four new automatic sorting lines with a total capacity of 158 kt per year. In most cases, manual sorting is used to reduce the transported weight of plastic waste, while automatic sorting lines separate the remaining, hardly recognized part. More than 60% of separately collected plastic is sorted and determined for material recovery.

Tool for optimization of energy consumption of membrane-based carbon capture.

The reduction of CO2 emissions is a very challenging issue. The capture of CO2 from combustion processes is associated with high energy consumption and decreases the efficiency of power-producing facilities. This can affect the economy and in specific cases, such as waste-to-energy plants, also their classification according to legislation. To allow the minimization of energy consumption, an optimization tool for membrane-based post-combustion capture was developed. The approach allows finding optimal membrane properties, membrane areas, and pressures for individual separation stages from the point of view of energy consumption. The core of the approach is represented by a mathematical model of the separation system that is based on a network flow problem. The model utilizes external simulation modules for non-linear problems to enable finding globally optimal results. These external modules approximate non-linear dependencies with any desired precision and allow using different mathematical descriptions of individual membrane stages without making changes to the model. Moreover, it allows easy substitution of the external module by experimental data and the model can be easily modified for specific purposes such as decision making, designing the separation process, as well as for regulation of process parameters in the case of dynamic operation. The ability of the model to optimize the process was verified on a case study and the results show that the optimization can significantly reduce the energy consumption of the process. For separation of 90% of CO2 at the purity of 95% from initial flue gas with 13% CO2 with state-of-the-art membranes based on the Robeson upper bound and three-stage process, the minimum power consumption was 1.74 GJ/tCO2 including final CO2 compression.