Characterisation of recycled fertilisers from dry toilet contents - analysis of nutrients, hygiene and harmful substances

Description

In the context of the project zirkulierBAR (Intermunicipal acceptance for sustainable value added from separately collected sanitary streams – from linear sanitation to circular nutrient recycling), a total of 11 composts were subjected to analysis in accordance with the specifications set forth in DIN SPEC 91421:2020-12. The objective was to ascertain the quality of recycling products derived from dry toilets for utilisation in horticulture. The analysis encompassed an assessment of the nutrient content, hygiene parameters and pollutants present, including heavy metals, polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), perfluorinated tensides (PFTs) and pharmaceutical residues. In order to identify potential discrepancies between laboratories, the composts were subjected to parallel analysis by two different project participants with regard to standard parameters, nutrient content, trace elements and heavy metals. The analysis of hygiene parameters and pollutants was conducted by external laboratories. It should be noted that the data set does not include information regarding the composting process. The goal of the data set is to expand the database on composts containing human faeces, thereby providing a basis for classifying the recycling route and promoting acceptance of circular use in order to preserve nutrients.

Steps to reproduce

The project partners analysed the samples in accordance with DINSPEC 91421 [1]. The majority of parameters were tested using methods specified in the Fertiliser Ordinance. The analysis for organic pollutants, pharmaceutical residues and hygiene parameters was carried out by accredited laboratories using legally prescribed methods. The pharmaceutical residues, except for beta-Estradiol, were analysed using accredited in-house methods (LC-MS/MS after extraction). Beta-Estradiol was measured using an in-house GC-MS/MS method after derivatisation. The methods employed are listed below.

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