The Influence of Drying Sewage Sludge with the Addition of Walnut Shells on Changes in the Parameters and Chemical Composition of the Mixture

Sebastian Kujawiak (), Małgorzata Makowska, Bogusława Waliszewska, Damian Janczak, Jakub Brózdowski, Wojciech Czekała and Artur Zyffert
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Sebastian Kujawiak: Department of Hydraulic and Sanitary Engineering, Poznań University of Life Sciences, Piątkowska 94A, 60-649 Poznań, Poland
Małgorzata Makowska: Department of Hydraulic and Sanitary Engineering, Poznań University of Life Sciences, Piątkowska 94A, 60-649 Poznań, Poland
Bogusława Waliszewska: Department of Chemical of Wood Technology, Poznań University of Life Sciences, Wojska Polskiego St. 28, 60-637 Poznań, Poland
Damian Janczak: Department of Biosystems Engineering, Poznań University of Life Sciences, Wojska. Polskiego 50, 60-627 Poznań, Poland
Jakub Brózdowski: Department of Chemical of Wood Technology, Poznań University of Life Sciences, Wojska Polskiego St. 28, 60-637 Poznań, Poland
Wojciech Czekała: Department of Biosystems Engineering, Poznań University of Life Sciences, Wojska. Polskiego 50, 60-627 Poznań, Poland
Artur Zyffert: Department of Hydraulic and Sanitary Engineering, Poznań University of Life Sciences, Piątkowska 94A, 60-649 Poznań, Poland

Energies, 2024, vol. 17, issue 18, 1-14

Abstract: One method of preparing sludge for management and use is solar drying. To intensify the drying process, natural lignocellulosic additives can be used to alter the structure of the sludge and accelerate water evaporation. Light, hard materials with low absorption capacity are best suited for this purpose, e.g., walnut shells, which are unused waste. The aim of the study was to determine the impact of the evaluation of walnut shells on the sludge drying process and to assess the impact of the drying process on the chemical, physical, and fuel properties of the additive. The moisture content, crushing strength, chemical composition, and physical and fuel properties of mixtures were determined. A small addition of walnut shells (25%) was found to accelerate the drying process even in winter and spring (up to 30 days) compared to sludge without additives. Walnut shells retain their chemical composition and strength despite unfavourable conditions and a chemically aggressive environment, indicating they may be reused. The mixture containing sewage sludge and walnut shells has a calorific value of 15.6 MJ/kg, which is similar to wood; it is also fully biodegradable and suitable as a fertiliser to improve soil structure, as it contains approx. 80–90% DM (including approx. 40% carbon, 3% nitrogen, and other elements, such as phosphorus and potassium.)

Keywords: sewage sludge; solar drying; walnut shells (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2024
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