• Energy Research
• 6. Clean water close

The present paper outlines an update of the fate and exposure part of the fate, exposure and effects model USES-LCA. The new fate and exposure module of USES-LCA was applied to calculate human population intake fractions and fate factors of the freshwater, marine and terrestrial environment for 3393 substances, including neutral organics, dissociating organics and inorganics, emitted to 7 different emission compartments. The human population intake fraction is on average 10(-5)-10(-8) for organics and 10(-3)-10(-4) for inorganics, depending on the emission compartment considered. Chemical-specific human population intake fractions can be 1-2.7 orders of magnitude higher or lower compared to the typical estimates. For inorganics, the human population intake fractions highly depend on the assumption that exposure via food products can be modelled with constant bioconcentration factors. The environmental fate factor is on average 10(-11)-10(-18) days m(-3) for organics and 10(-10)-10(-12) days m(-3) for inorganics, depending on the receiving environment and the emission compartment considered. Chemical-specific environmental fate factors can be 1-8 orders of magnitude higher or lower compared to the typical estimates. The largest differences between the new and old version of USES-LCA are found for emissions to air and soil. This is caused by a significant change in the structure of the air and soil compartments in the new version of USES-LCA, i.e. the distinction between rural and urban air, including rain-no rain conditions and including soil depth dependent intermedia transport.

Purpose: This study aims to minimize the environmental impacts of thermal seawater desalination by optimizing the required fossil fuel mixture. Life cycle assessment (LCA) is applied to simulate the environmental impacts for each fuel mixture. To prevent mixture designs inherited collinearly from correlating LCA results, fuel mixtures are first sampled prior to conducting LCA and then later optimized using a regression-based methodology to reduce entailed environmental impacts. Method: Setting the functional unit to 1 m 3 of desalinated water induces different reference flows of energy requirements depending on the fuels used. Increasing the level of any fuel type within the fuel mixture scenario will cause a decrease in the level of the other fuel type(s) included. An augmented simplex lattice mixture (ASLM) design is applied to indicate correct experimental conditions and to prevent the correlation due to collinearity inherited from the nature of mixture problems. Regression models are formulated to represent life cycle impact assessment (LCIA) results in a closed form suitable for response surface methodology (RSM) optimization. An overall composite sustainability index (CSI) is a single index calculated by aggregating and normalizing corresponding LCIA responses of different units, ranges, and scales using the geometric mean-based method. Results and discussion: The results indicate that marine sediment ecotoxicity (MSE) is the category most adversely affected by multistage flash distillation (MSF). On a nationwide scale, the LCA optimized results scored a 17% reduction in associated environmental impacts, which corresponds to a 4.2% reduction in the county’s carbon footprint and a 62% reduction in MSE while incurring a minor retrofitting cost to desalination facilities. Conclusions: High MSE results due to excessive fossil fuel consumption/burning in MSF should gain as much attention as paid toward global warming potential. High MSE entails the risk of having heavy metals entering the food chain. On the other hand, the geometric mean approach is found to be an effective model to aggregate the LCIA results into a single index while avoiding the subjectivity of the value judgment used in LCIA weighting. This approach serves as a unit-free rescaling method that is robust to outliers or large values examined across different LCIA impacts.

In economics, opportunity cost is defined as the benefit foregone by choosing another course of action. Considering opportunity costs enables the improved handling of trade-offs to better support strategic decision-making. We introduce the concept of opportunity cost into life cycle assessment (LCA). In our framework, opportunity cost extends the system expansion paradigm to support better alignment with a circular economy (CE). Opportunity cost thinking is considered to be most useful for the efficient allocation of scarce economic capital for the creation of economic value. In the environmental domain, we use such thinking to account for the implications of ‘wasting waste’. In this paper, we consider a case of treated wastewater sludge being used as a source of nutrients as a vehicle to study the points at which LCA can support a CE. Our conclusions, however, have wider repercussions because there are many more situations in which product systems are analytically demarcated from the web of connections in which they are embedded.

AbstractPolymerization strategies aiming at further reducing the environmental impact of the already “green” emulsion polymerization process were investigated. Life cycle assessment showed that non‐isothermal strategies starting at low temperature resulted in an environmental impact lower than the isothermal ones. Nevertheless, the major part of the environmental impact was due to raw materials. The effect of the polymerization strategy on polymer microstructure was investigated.magnified image