The integration of an off-grid solar-assisted heat pump (SHP) and a sequencing batch biofilter granular reactor (SBBGR) for thermal energy recovery from wastewater was assessed by means of a prospective life cycle assessment (LCA) and life cycle costing (LCC), by theoretically scaling up a pilot installation in Bari, Italy, to a full-scale unit designed for 5000 person-equivalents. The LCA and LCC included all activities in the life cycle of the SHP and wastewater treatment plant (WWTP), namely construction, operation and end-of-life. The thermal energy produced by the SHP was assessed as supplying heating and cooling for an air-conditioning system, displacing a conventional air-source heat pump powered by electricity from the grid. This integrated system was compared to a reference situation where wastewater is treated in a conventional WWTP applying activated sludge with no thermal energy recovery system, showing clear environmental benefits in all impact indicators, such as a 42% reduction in greenhouse-gas emissions and a cost reduction of 53%. Several sensitivity analyses confirmed these findings, with the exception of the price rebound effect, which showed that the lower cost of the integrated system could lead to overturning the environmental benefits. As a limitation of the study, the distribution of the supplied air-conditioning to meet a demand off-site the WWTP premises, such as in residential buildings or hotels, was not included. Therefore, our results constitute only a preliminary positive outcome that should be validated in a real-life application.
The panel review resulted in a study report, prepared by Procter & Gamble and Enviroconseil. The review was assessed for compliance with ISO 14040/44 concerning LCA studies intended to support a comparative assertion disclosed to the public. Besides checking for ISO compliance, our role also included reviewing the wastewater modelling carried out in the study by means of our WW LCI tool.
Refractories are ceramic materials used to protect equipment in industries working at high temperatures. They contain compounds like aluminium silicates, magnesium, dolomite, chromite, zirconium, carbides, nitrides and oxides. Steel production is the main user of these materials, consuming around 70% of their total production. About 4 million tonnes of refractories are produced in Europe, representing 11% of world production. Most of the raw materials involved are considered as Critical Raw Materials by the EU but, surprisingly, only 7% of the raw material volume arises from recycled sources globally. In the European steel sector, recycling and valorisation of refractory materials is most often sporadic. LIFE 5REFRACT aims at applying a "5R" (reduce, reuse, remanufacture, recycle, re-educate) approach within the steel sector to reach an integral valorisation of refractory materials. The project will constitute the first industrial and systematic demonstration experience dealing with refractory waste in the European steel sector, studying different waste management alternatives for refractory waste produced at the SIDENOR steel mill in Bizkaia, Spain. Specific aims of the project include, among others, recovering up to 80% of refractory waste, developing recycled refractory products and establishing guidelines for the European steel sector to adopt these strategies.
Read more on the official LIFE Programme website: https://webgate.ec.europa.eu/life/publicWebsite/project/details/4926
Read the paper: Life cycle assessment of refractory waste management in a Spanish steel works
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Slides available here: WW LCI_SETAC Nantes. Extended abstract available below.
Existing models for wastewater treatment in LCA reflect average conditions in wastewater treatment plants (WWTPs), rather than the specific fate of particular chemicals and they omit the impact of direct discharges. We present a model and tool to calculate life cycle inventories (LCIs) of chemicals in wastewater, WW LCI. It attributes the exchanges with the technosphere and the environment taking into account the expected behaviour of individual chemicals. The model covers treatment of organic and inorganic chemicals and the WWTP is modelled taking into account the partitioning of each chemical to air, sludge, treated effluent, and depending on its degradability, the transformation by microorganisms to CO2 and excess sludge. Sludge is treated by anaerobic digestion and the fate of any fraction of chemical released to the environment (e.g. treated effluent, direct discharges) is assessed in terms of greenhouse-gas (GHG) as well as nutrient (N, P) emissions following degradation in environmental compartments. Sludge disposal includes incineration, landfilling and agricultural reuse. The model is programmed in Excel and accommodates simultaneous calculations for 30 chemicals, either individually or as a mixture. The resulting LCIs can be automatically imported into the LCA software SimaPro.
The applicability of WW LCI is shown in a case study on three detergent formulations (powder, liquid, concentrate) including 28 chemical ingredients. The impact of these formulations is assessed for a functional unit of one wash, and the results are compared to those of the WWTP model developed for ecoinvent v2. The system boundaries include only the end-of-life stage, i.e. discharge of the three formulations after use in a washing machine, and the impact categories assessed are GHG emissions, freshwater and marine eutrophication and freshwater ecotoxicity.
The results show that, when assessed individually, the impact of some chemicals can be orders of magnitude different when assessed with the ecoinvent model and with WW LCI. When assessed as a mixture (detergent formulations), differences are lower between models and the ranking of formulations is not changed. The main advantages of WW LCI over the ecoinvent model are that it addresses the impacts from direct discharge, relevant for developing countries where connection to WWTPs is limited, and second that it provides a complete substance flow analysis of the assessed chemicals across all environmental impact categories.
Slides available here: WW LCI_SETAC Montpellier.
Slides available here: WW LCI_SETAC Brussels.
Slides available her: Social footprint presentation SETAC Rome. Extended abstract below.
