Odors and gas emissions during the ceramic sintering of sewage sludge : guidelines for industrial implementation

TLDR: In this paper, the data of gaseous, particulate matter and odors emissions produced in the sintering of clay/sewage sludge ceramic pieces were analyzed and the main guidelines to be followed by any implementation of industrial ceramic plants to be respectful with the environment rules are proposed.

Abstract: Numerous research reported in the scientific literature show the feasibility of inerting sewage sludge in ceramic matrices as structural or red ceramic material for construction. However, its industrial implementation is hampered by a social rejection from the environmental movements. Is this process an undercovered waste incineration or rather a pyrolysis process with reduced environmental impact? If there are countless incinerators, why does the manufacturing process of clay bricks with sewage sludge have legislative difficulties and generates numerous social conflicts? This study analyzes the data of gaseous, particulate matter and odors emissions produced in the sintering of clay/sewage sludge ceramic pieces. According to laboratory tests, VOC emissions for the clay/sludge material were in general higher than those from conventional ceramics. However, no VOC exceeded the threshold limit values and only a few compounds showed concentrations that exceeded their odor detection threshold. Besides, three inorganic pollutants exceeded the maximum levels (NOx, suspended particles and HCl). In a test at industrial level, the most important emissions were those of CO (1100 mg/Nm3), TOC (1085 mg/Nm3) and HCl (71 mg/Nm3). Finally, from this experience, the main guidelines to be followed by any implementation of industrial ceramic plants to be respectful with the environment rules are proposed.