Comparing the agrochemical properties of compost and vermicomposts produced from municipal sewage sludge digestate

• Published in: Bioresource technology Vol. 291; p. 121861
• Main Authors: Rékási, Márk, Mazsu, Nikolett, Draskovits, Eszter, Bernhardt, Botond, Szabó, Anita, Rivier, Pierre-Adrien, Farkas, Csilla, Borsányi, Barbara, Pirkó, Béla, Molnár, Sándor, Kátay, György, Uzinger, Nikolett
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.11.2019
• Subjects: Agrochemicals - analysis; Agrochemicals - metabolism; Animals; Compost; Composting; Macronutrients; Oligochaeta - metabolism; Organic matter quality; Plant growth regulator; Sewage - chemistry; Vermicompost; Vermicompost; Organic matter quality; Macronutrients; Compost; Plant growth regulator
• ISSN: 0960-8524; 1873-2976
• DOI: 10.1016/j.biortech.2019.121861

[Display omitted] •Fertilisers were produced from precomposted sewage sludge digestate mixtures.•Various additives, composting and vermicomposting were tested in the process.•Nutrient content and availability were almost the same in composts and vermicomposts.•Vermicomposting did not result in better organic matter quality.•The concentration of the plant growth regulator kinetin was higher in vermicomposts. The aim of this work was to investigate whether the agronomic traits of vermicompost prepared from partially stabilised sewage sludge digestate after thermophilic composting were more favourable than those of conventional compost. The effects of various additives (green waste, spent mushroom compost, wheat straw, biochar) were also tested after 1.5 months precomposting followed by 3 months vermicomposting with Eisenia fetida or by compost maturing. Vermicomposting did not result in significantly more intensive mineralisation than composting; the average organic carbon contents were 21.2 and 22.2% in vermicomposts and composts, respectively. Hence, the average total (N: 2.4%; P: 1.9%; K: 0.9%) and available (N: 160 mg/kg; P: 161 mg/kg; K: 0.8%) macronutrient concentrations were the same in both treatments. The processing method did not influence the organic matter quality (E4/E6) either. However, on average the concentration of the plant growth regulator kinetin was more than twice as high in vermicomposts.