Circular economy through waste reverse logistics under extended producer responsibility in Finland.

Extended producer responsibility (EPR) is commonly implemented as a strategy in waste management. The core of the concept itself is a waste reverse logistics (WRL), which dictates how the collection, inspection and processing of end-of-life products are performed. Existing studies of EPR mainly focused on single products instead of using broader perspective on national level. Its contribution towards circular economy through slowing and closing the loops also has not been widely discussed. This study examined the system architecture of the policy instruments used in the EPR and the similarities of the WRL networks across different products. A case study was used to investigate six products: portable batteries and accumulators, paper, packaging, vehicles, electrical and electronic equipment (EEE) and tyres. The study generated a WRL framework. It is also observed that closing the loop through recycling is the primary circular strategy and is found in all products, whereas closing and slowing the loop strategy through reuse/repair, remanufacture and repurposing is found in packaging, tyres, vehicles and EEE. This study shows that EPR can close the material loop, although improvement in design for the environment is necessary. It creates challenges and opportunities for the government, producer responsibility organization and producers to improve existing conditions by implementing new initiatives such as design for the environment indicators, standardization, tax and subsidy systems and tariffs for disposal fees.

Smart textile waste collection system - Dynamic route optimization with IoT.

Increasing textile production is associated with an environmental burden which can be decreased with an improved recycling system by digitalization. The collection of textiles is done with so-called curbside bins. Sensor technologies support dynamic-informed decisions during route planning, helping predict waste accumulation in bins, which is often irregular and difficult to predict. Therefore, dynamic route-optimization decreases the costs of textile collection and its environmental load. The existing research on the optimization of waste collection is not based on real-world data and is not carried out in the context of textile waste. The lack of real-world data can be attributed to the limited availability of tools for long-term data collection. Consequently, a system for data collection with flexible, low-cost, and open-source tools is developed. The viability and reliability of such tools are tested in practice to collect real-world data. This research demonstrates how smart bins solution for textile waste collection can be linked to a dynamic route-optimization system to improve overall system performance. The developed Arduino-based low-cost sensors collected actual data in Finnish outdoor conditions for over twelve months. The viability of the smart waste collection system was complemented with a case study evaluating the collection cost of the conventional and dynamic scheme of discarded textiles. The results of this study show how a sensor-enhanced dynamic collection system reduced the cost 7.4% compared with the conventional one. We demonstrate a time efficiency of -7.3% and that a reduction of 10.2% in CO2 emissions is achievable only considering the presented case study.

Monetary and environmental damage cost assessment of source-separated biowaste collection: Implications of new waste regulation in Finland.

This study develops a cost model covering monetary and environmental damage costs for source-separated biowaste collection. The model provides an improved basis for decision-making by including environmental damage costs compared to the assessment that considers the only monetary cost. The monetary cost calculation integrated route optimisation using existing road networks, while the environmental damage cost was estimated using the life cycle impact assessment method based on the endpoint (LIME) model. The model was tested in the Finnish case where the new law implements the stricter requirement for source-separated biowaste. The costs of collection, transportation and treatment of three different scenarios were assessed: mixed waste under the old law (MW-OL), biowaste under the new law (B-NL) and mixed waste without biowaste under the new law (MW-NL). The results showed the economic and environmental benefits of sourced separated biowaste. The overall cost of collection and transportation (CT) under the old law and new laws were 80.7 € Mg-1 and 81.1 € Mg-1, respectively. Treatment costs were 79 € Mg-1 and 64.8 € Mg-1 under the old and new laws, respectively. The damage costs for CT under the old and new laws were 0.23 € Mg-1 and 0.24 € Mg-1, respectively. At the same time, the damage costs from the treatment stage were 4.9 € Mg-1 and 3.5 € Mg-1 under the old law and new law, respectively. The model supports decision-making when the collection scheme requires a change. Failing to plan an optimised solution and cost will lead to inefficient systems.

Multi-objective optimization to improve energy, economic and, environmental life cycle assessment in waste-to-energy plant.

This paper presents a multi-objective optimization (MOO) of waste-to-energy (WtE) to investigate optimized solutions for thermal, economic, and environmental objectives. These objectives are represented by net efficiency, total cost in treating waste, and environmental impact. Integration of the environmental objective is conducted using life cycle assessment (LCA) with endpoint single score method covering direct combustion, reagent production and infrastructure, ash management, and energy recovery. Initial net efficiency of the plant was 16.27% whereas the cost and environmental impacts were 75.63 €/ton-waste and -1.21 × 108 Pt/ton-waste, respectively. A non-dominated sorting genetic algorithm (NSGA-II) is applied to maximize efficiency, minimize cost, and minimize environmental impact. Highest improvement for single objective is about 13.4%, 10.3%, and 14.8% for thermal, economic, and environmental, respectively. These improvements cannot be made at once since the objectives are conflicting. These findings highlight the significance role of decision makers in assigning weight to each objective function to obtain the optimal solution. The study also reveals different influence among decision variable, waste input, and marginal energy sources. Finally, this paper underlines the versatility of using MOO to improve WtE performance regarding the thermal, economic, and environmental aspects without requiring additional investment.

Soluble microbial products (SMPs) in a sequencing batch reactor with novel cake filtration system.

The formation, composition and characteristics of soluble microbial products (SMPs) were investigated in a novel system which coupled a sequencing batch reactor with a cake filtration system. Both suspended solids (SS) and turbidity were significantly removed, resulting in effluent SS of 0.12 mg L-1 and turbidity of 0.72 NTU after cake filtration. The average concentrations of proteins and carbohydrates decreased respectively from 4.0 ± 0.4 and 7.1 ± 0.6 mg/L in the sequencing batch reactor (SBR) mixed liquor, to 0.85 ± 0.21 and 1.39 ± 0.29 mg/L in the cake filtration effluent. Analysis of the molecular weight (MW) distribution of SMPs revealed a substantial reduction in the intensity of high-MW peaks (503 and 22.71 kDa) after cake filtration, which implied the sludge cake layer and the underlying gel layer may play a role in the effectiveness of cake filtration beyond the physical phenomenon. Three-dimensional excitation emission matrix fluorescence spectroscopy indicated that polycarboxylate- and polyaromatic humic acids were the dominant compounds and a noticeable decrease in the fraction of these compounds was observed in the cake filtration effluent. Analysis with GC-MS set for detecting low-MW SMPs identified aromatics, alcohols, alkanes and esters as the dominant compounds. SMPs exhibited both biodegradable and recalcitrant characteristics. More SMPs (total number of 91) were accumulated during the SBR start-up stage. A noticeable increase in the aromatic fractions was seen in the SBR effluent accoutring for 39% of total compounds, compared to the SBR mixed liquor (28%). Fewer compounds (total number of 66) were identified in cake filtration effluent compared to the SBR effluent (total number of 75).