Substance Flow Analysis Approach Research Articles

Tracing copper flows in Pakistan: A substance flow analysis approach

AbstractCopper is essential to the global economy and plays a significant role in the global energy transition towards low carbon development. This study investigates copper metabolism in Pakistan from 2005 to 2020 by using a substance flow analysis (SFA) method so that valuable insights can be obtained for supporting sustainable copper utilization in Pakistan where the mineral sector contributes greatly to the national development. Our results show that over 75.83% of the mined copper has been consumed domestically, and a large amount of copper ores has been imported to support domestic consumption. The recovery efficiency of copper was 57.37%, 89.90%, 71.96%, 68.12%, and 75.84% in the stages of mining, smelting, fabrication, manufacturing, and local use, respectively. The cumulative copper loss reached 90.34 kt during this study period, indicating that it is urgent to improve copper recycling. In summary, these findings provide valuable implications to those policy‐makers so that they can prepare appropriate copper management policies to improve the overall copper resource efficiency.

Potential Nutrient Conversion Using Nature-Based Solutions in Cities and Utilization Concepts to Create Circular Urban Food Systems

The present food system is characterized by a linear flow of resources from rural areas into cities, where most food is consumed and essential nutrients discharged as wastewater. Limited water and phosphorus resources and large carbon footprints of chemical fertilizers drive increased recovery of water and nutrients for reuse in agriculture. Alongside end-of-pipe technologies at conventional wastewater treatment plants, nature-based solutions provide a robust and low-energy alternative solution. This paper assesses the potential of treatment processes using NBS to close water and nutrient cycles in the urban food system. A Substance Flow Analysis approach is used to quantify the recoverable urban nutrient (nitrogen, phosphorus, potassium) budget contained in household wastewater and biodegradable kitchen waste, using the city of Vienna, Austria, as an example. The developed model reflects the metabolization of water and nutrients by treatment wetlands and biogas digesters into fertigation water and fertilizer. It differentiates between specific crop nutrient requirements and yields, and by greenhouse and outdoor farming conditions in a temperate climate. Results indicate that, using NBS, the wastewater and kitchen waste from 77,250 persons could fully cover the nitrogen and phosphorus fertilizer demand of the entire vegetable production in Vienna, which currently supplies one-third of Vienna’s vegetable consumption. Additional people connected to the system can supply significant excess nutrients to produce other crops within and beyond the city. The model can inform selection and design of NBS for nutrient recovery and reuse, and support integrated planning regarding use of secondary nutrient sources and optimization of secondary nutrient utilization.Graphical

A reactive nitrogen budget for forest land and wetlands in Latvia and Estonia

ABSTRACT Human intervention in global nitrogen cycling has led to excess reactive nitrogen (Nr) flows to the environment, impacting terrestrial ecosystems as well as the quality of the atmosphere and waterbodies. This paper presents the results of a study that quantified and compared the main flows of Nr through forest land and wetlands in Latvia and Estonia using substance flow analysis approach based on data from statistics, research results, reports, monitoring programmes, data bases and expert estimations. Input and output flows to and from the forest land and wetlands both in Latvia and Estonia are well balanced, with a trend to be a Nr sink (+1.2 kT N yr−1) for Latvia and a Nr source (−6.5 kT N yr−1) for Estonia. Major input flow to the studied pools in Estonia is a soil nitrogen stock used for forest growth, while in Latvia, it is atmospheric deposition and biological fixation. Major output flow of Nr in both countries occurs via wood and peat for industrial uses. Emissions of Nr to the atmosphere and hydrosphere from forest land and wetlands are significantly lower compared to human-related emissions such as industries, energy production, agriculture, human settlements, and transport.

Assessment of nitrogen and phosphorus flows in agricultural and urban systems in a small island under limited data availability

Nitrogen (N) and phosphorus (P) are two essential macronutrients required in agricultural production. The major share of this production relies on chemical fertilizer that requires energy and relies on limited resources (P). Since these nutrients are lost to the environment, there is a need to shift from this linear urban metabolism to a circular metabolism in which N and P from domestic waste and wastewater are reused in agriculture. A first step to facilitate a transition to more circular urban N and P management is to understand the flows of these resources in a coupled urban-agricultural system. For the first time this paper presents a Substance Flow Analysis (SFA) approach for the assessment of the coupled agricultural and urban systems under limited data availability in a small island. The developed SFA approach is used to identify intervention points that can provide N and P stocks for agricultural production. The island of St. Eustatius, a small island in the Caribbean, was used as a case study. The model developed in this study consists of eight sub-systems: agricultural and natural lands, urban lands, crop production, animal production, market, household consumption, soakage pit and open-dump landfill. A total of 26 flows were identified and quantified for a period of one year (2013). The results showed that the agricultural system is a significant source for N and P loss because of erosion/run-off and leaching. Moreover, urban sanitation systems contribute to deterioration of the island's ecosystem through N and P losses from domestic waste and wastewater by leaching and atmospheric emission. Proposed interventions are the treatment of blackwater and greywater for the recovery of N and P. In conclusion, this study allows for identification of potential N and P losses and proposes mitigation measures to improve nutrient management in a small island context.

Substance flow analyses of phthalates and nonylphenols in stormwater

The occurrence of nonylphenol and several phthalates in water environments is highly undesired because of their negative effects on aquatic organisms. The objectives of this study were to identify emission sources of phthalates, nonylphenol and its ethoxylates (NP/EOs) in urban stormwater, and to quantify the substance fluxes from the source to the stormwater system, using the methodology of substance flow analysis (SFA). The SFA, applied on an urban motorway area, showed that phthalates are mainly emitted from vehicles and coated roofing material, whereas the major NP/EOs sources are vehicles and concrete. It was estimated that approximately 4.1 kg of four selected phthalates and more than 400 g of NP/EOs are emitted annually to stormwater in the studied area. The SFA approach presented in this study, using factors that express the emission rate of a specific substance from a specific source, could be applied in urban catchments of various character to estimate fluxes of water contaminants.

A life cycle methodology for mapping the flows of pollutants in the urban environment

This paper presents an integrated life cycle methodology for mapping the flows of pollutants in the urban environment, following the pollutants from their sources through the environment to receptors. The sources of pollution that can be considered by this methodology include products, processes and human activities. Life cycle assessment (LCA), substance flow analysis (SFA), fate and transport modelling (F&TM) and geographical information systems (GIS) have been used as tools for these purposes. A mathematical framework has been developed to enable linking and integration of LCA and SFA. The main feature of the framework is a distinction between the foreground and background systems, where the foreground system includes pollution sources of primary interest in the urban environment and the background comprises all other supporting activities occurring elsewhere in the life cycle. Applying the foreground–background approach, SFA is used to track specific pollutants in the urban environment (foreground) from different sources. LCA is applied to quantify emissions of a number of different pollutants and their impacts in both the urban (foreground) and in the wider environment (background). Therefore, two “pollution vectors" are generated: one each by LCA and SFA. The former comprises all environmental burdens or impacts generated by a source of interest on a life cycle basis and the latter is defined by the flows of a particular burden (substance or pollutant) generated by different sources in the foreground. The vectors are related to the “unit of analysis" which represents a modified functional unit used in LCA and defines the level of activity of the pollution source of interest. A further methodological development has also included integration of LCA and SFA with F&TM and GIS. A four-step methodology is proposed to enable spatial mapping of pollution from sources through the environment to receptors. The approach involves the use of GIS to map sources of pollution, application of the LCA–SFA approach to define sources of interest and quantify environmental burdens and impacts on a life-cycle basis. This is followed by F&TM to track pollution through the environment and by the quantification of site-specific impacts on human health and the environment. The application of the integrated methodology and the mathematical framework is illustrated by a hypothetical example involving four pollution sources in a city: incineration of MSW, manufacture of PVC, car travel and truck freight.