This study uses a comprehensive life cycle assessment to evaluate the environmental sustainability of two acid concentrate delivery methods used in haemodialysis: traditional single-use acid concentrate bags and the Fresenius Granumix central delivery system. Life cycle assessment is a widely adopted method for quantifying the environmental impacts associated with a product or process across its full life cycle—from raw material extraction to end-of-life disposal. Data collection and modelling were carried out between April and September 2024 at the AOU Policlinico di Modena in Italy. The study involved detailed process mapping, material inventory, energy and water usage, and waste management assessment for both systems.

Creating flow diagrams

The first step involved developing a detailed flow diagram to visualise the entire life cycle of both dialysis methods. The flow diagram serves as a graphical representation of the processes and stages involved in the production, use and waste of the two dialysis methods. All processes involved in the life cycle of methods were identified, including materials, products and waste.

Each process was mapped out. Flow diagrams were created using a professional page layout software, Visio [9] – See Fig. 1

Fig. 1

Flow Diagram of acid bags vs Acid Concentrate

The flow diagrams were verified through discussion and consultation with clinical staff and dialysis experts to ensure accuracy.

Data collection

Data were collected from the Nephrology Dialysis and Kidney Transplant Department at the AOU Policlinico di Modena, Italy, and from a previous study on Acid concentrate by nephrologists and researchers at the same hospital [8].

Collected data included the number of acid concentrate bags used annually, the volume of dialysate produced by the Granumix machine, the amount of waste generated, including packaging waste, acid solution and other related items and materials. Resource consumption data, including energy and water usage were also collated.

Inputting data into OpenLCA.

The material weights and types alongside the process flow diagrams were input into OpenLCA [10]. This involved compiling all relevant data for both dialysis methods.

The data were used to model the life cycle of both dialysis methods.

Impact assessment was conducted using various environmental impacts such as climate change, ecotoxicity, resource use, water use in OpenLCA alongside the Eco Invent database [11]. This step involved calculating the environmental impacts across various impact categories, such as global warming potential, ecotoxicity and acidification.

Bicarbonate cartridges were excluded from this life cycle assessment as their use and environmental impact were identical across both systems and therefore would not affect the comparative results.

The full data set for this study can be found at Larkin, J. (2025). Green Haemodialysis: Comparison of Dialysis Bags Versus Fresenius Granumix Water Recycling System at the AOU Policlinico di Modena, Italy (Version v1) [Data set]. Zenodo. https://doi.org/10.5281/zenodo.14610055.

Functional unit

The functional unit for this study is defined as the amount of dialysate required for one haemodialysis treatment for a single patient. Each session was assumed to last 4 h with a dialysate flow rate of 500 mL/min, resulting in a total of 120 L of dialysate per treatment. This standardised prescription allows for comparability across haemodialysis units and reflects common clinical practice.

Impact categories in life cycle assessment

This study used OpenLCA to analyse a range of environmental impact categories relevant to dialysis delivery systems. These included:

Acidification potential, measured in mol H⁺-eq, which reflects the emission of substances (e.g., SO₂, NOₓ, NH₃) that increase the acidity of soil and water bodies, potentially harming ecosystems.

Eutrophication, measured in kg P-eq or kg N-eq, refers to the nutrient enrichment of water bodies (freshwater, marine, or terrestrial) that can lead to excessive algal growth and oxygen depletion.

Human toxicity (carcinogenic and non-carcinogenic), measured in comparative toxic units for humans, estimates the risk to human health from exposure to harmful substances over the product lifecycle.

Freshwater ecotoxicity, measured in comparative toxic units for ecosystems, evaluates the potential of emissions to cause toxic effects in aquatic organisms.

Other categories include climate change (kg CO₂-eq), ozone depletion (kg CFC-11-eq), particulate matter formation (disease incidence), water use (m3 world eq. deprived), land use, and resource depletion (e.g., kg Sb-eq for metal use).

A full glossary of all impact categories, including definitions and units, is provided in the supplementary material (Supplementary Material S1: life cycle assessment Impact Categories).

System boundaries

Figure 2 outlines the system boundaries, covering the full life cycle of traditional acid concentrate bags and the Fresenius Granumix system, from raw material extraction to end-of-life waste. For acid bags, materials include plastics, acid solution chemicals, and packaging (3.8–4.5 L per bag). Granumix materials include metals, plastics, and other system components. The filter, including its material composition, packaging, transport distances, and replacement frequency, was included in the life cycle inventory for the Granumix system to ensure a complete and representative environmental assessment.

Fig. 2

System boundaries for Acid Concentrate Bags and the Fresenius Granumix System. The system boundary shows the “cradle to grave” analysis of the life cycle assessment

Manufacturing includes plastic bag and acid solution production for the bags, and full system and component assembly for the Granumix. Transportation covers raw material delivery, product distribution, and maintenance-related transport for both systems. Waste transport is also included.

Both the use and waste phases are assessed, including disposal of used bags and solution, as well as waste from Granumix components.

Product manufacture

The product materials and weight information were retrieved from the previous study which investigated the difference between acid concentrate bags and the Granumix system with regard to the quantity of each material and the amount of waste generated [9]. The manufacturing processes that were used in the production of all the products were found through product safety data sheets and assumptions. These have all been referenced at Larkin, J. (2025). Green Haemodialysis: Comparison of Dialysis Bags Versus Fresenius Granumix Water Recycling System at the AOU Policlinico di Modena, Italy (Version v1) [Data set]. Zenodo. https://doi.org/10.5281/zenodo.14610055. The energy usage of the machinery that was used to manufacture the products was provided by Eco Invent.

Transportation

Transportation distances were calculated from the manufacturing site to the AOU Policlinico di Modena using Google Maps for road transport and Fluentcargo.com for shipping distances. These tools provided the most geographically direct and commonly used routes for freight transport, based on available infrastructure. Actual routes may vary depending on specific logistics provider operations, but the shortest and fastest available routes were used as a conservative estimate for environmental modelling.

Information on modes of transport (e.g., truck, ship) was obtained from product manufacturers where possible. In instances where exact transport logistics were unavailable, reasonable assumptions were made based on standard industry practices for medical device distribution, considering typical transport modes, packaging formats, and the origin–destination pairing.

Waste

To evaluate the environmental impact of waste, data were collected from hospital administrative staff on the hospital’s waste management processes. Healthcare waste and recycled materials were the main focus. Hospital admin staff were able to identify waste management providers, and the waste processes for the acid concentrate bags as well as the recycling of the Granumix container. Waste was categorised into healthcare waste and recyclable materials to assess their environmental impacts. The quantity of unused acid solution was estimated based on observational data provided by the nursing staff at AOU Policlinico di Modena, with an average of 0.4 L discarded per bag.

In Italy, acid concentrate bags are classified as hazardous medical waste due to potential chemical contamination and are typically incinerated as part of national healthcare waste protocols. This may differ from practices in other countries, where such waste might be considered non-hazardous and treated via alternative methods such as autoclaving or landfill disposal. This has implications for the generalisability of toxicity and waste-related results in the life cycle assessment.

Data analytics

The process involved entering the collected data into the OpenLCA software that incorporated all aspects of the products with the cradle to grave approach [12]. A detailed life cycle model was created using various impact categories such as acidification, climate change, and ecotoxicity to calculate environmental impacts across multiple categories, including areas such as global warming potential, resource depletion, and human health impacts. The analysis identified and quantified the most significant environmental contributors between acid concentrate bags and the Fresenius Granumix system. Detailed assessments of each process and material involved were included.