title: Utilization of sewage sludge in the manufacture of lightweight aggregate.
abstract: This paper presents a comprehensive study on the possibility of sewage sludge management in a sintered ceramic material such as a lightweight aggregate. Made from clay and sludge lightweight aggregates were sintered at two temperatures: 1100 °C (name of sample LWA1) and 1150 °C (name of sample LWA2). Physical and mechanical properties indicate that the resulting expanded clay aggregate containing sludge meets the basic requirements for lightweight aggregates. The presence of sludge supports the swelling of the raw material, thereby causing an increase in the porosity of aggregates. The LWA2 has a lower value of bulk particle density (0.414 g/cm(3)), apparent particle density (0.87 g/cm(3)), and dry particle density (2.59 g/cm(3)) than it is in the case of LWA1 where these parameters were as follows: bulk particle density 0.685 g/cm(3), apparent particle density 1.05 g/cm(3), and dry particle density 2.69 g/cm(3). Water absorption and porosity of LWA1 (WA = 14.4 %, P = 60 %) are lower than the LWA2 (WA = 16.2 % and P = 66 %). This is due to the higher heating temperature of granules which make the waste gases, liberating them from the decomposition of organic sewage sludge. The compressive strength of LWA2 aggregate is 4.64 MPa and for LWA1 is 0.79 MPa. Results of leaching tests of heavy metals from examined aggregates have shown that insoluble metal compounds are placed in silicate and aluminosilicate structure of the starting materials (clays and sludges), whereas soluble substances formed crystalline skeleton of the aggregates. The thermal synthesis of lightweight aggregates from clay and sludge mixture is a waste-free method of their development.
authors.affiliation: Civil Engineering and Architecture Faculty, Lublin University of Technology, Nadbystrzycka 40, 20-618, Lublin, Poland.
authors.forename: Małgorzata
authors.initials: M
authors.lastname: Franus
authors.affiliation: Civil Engineering and Architecture Faculty, Lublin University of Technology, Nadbystrzycka 40, 20-618, Lublin, Poland.
authors.forename: Danuta
authors.initials: D
authors.lastname: Barnat-Hunek
authors.affiliation: The Mineral and Energy Economy Research Institute of the Polish Academy of Sciences, Wybickiego 7, 31-261, Kraków, Poland. mwdowin@gmail.com.
authors.forename: Magdalena
authors.initials: M
authors.lastname: Wdowin
mesh_terms: D000538:Aluminum Silicates; D000077215:Clay; D004784:Environmental Monitoring; D006358:Hot Temperature; D019216:Metals, Heavy / Q000032:analysis; D059027:Recycling / Q000379:methods*; D012722:Sewage; D013696:Temperature; D014865:Waste Disposal, Fluid
chemical_list: D000538:Aluminum Silicates; D019216:Metals, Heavy; D012722:Sewage; C049037:aluminosilicate; D000077215:Clay
keywords: Heavy metals; Leachability test; Lightweight aggregates; Physical and mechanical properties of lightweight aggregates; Sewage sludge