Geo-environmental and geotechnical characterization of municipal solid waste from the selective collection in São Paulo city, Brazil

Abstract

This paper presents the characterization of municipal solid waste (MSW) randomly collected from two material recovery facilities in São Paulo city, before (input -recyclables) and after (output -rejects) the sorting processes. Geo-environmental and geotechnical tests were performed on shredded samples and a digestion method was applied to detect the metals As, Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Zn concentrations using an ICP OES. The objective was to assist future activities of integrated solid waste management and soil pollution. Results showed different particle sizes comparing the input (44.6%) and the output MSW (75.1%) passing through the 100-mm sieve. Organic matter and ash contents indicated the influence of inorganic carbon due to the plastics' presence, with values varying between 6 and 13%. The pH values obtained were neutral and the electrical conductivity of the MSW rejects suggested a higher amount of ions, with values above 1000 µS/cm. Metals analyses show that Cd, Cu, Ni, Pb, and Zn are present in high concentrations, depending on the types of the materials. Standard Proctor compaction curves yielded maximum dry unit weight varying from 6.6 to 10.0 kN/m 3 and optimum moisture contents from 20 to 42%. Cohesion ranged from 1.3 to 31.3 kPa and friction angle from 3.2 to 42.9°. The results are comparable with those obtained for other countries using different MSW treatments and contribute to the data basis for MSW from the selective collection, aiming the integrated solid waste management, serving for other countries that adopt MSW sorting and recycling.

An overview of in situ testing and geophysical methods to investigate municipal solid waste landfills

“…Laboratory tests under rigorously controlled conditions can contribute to important insights into the constitutive hydro-bio-mechanical behavior of MSW (Athanasopoulos 2011 ), but there are limitations regarding the extrapolation of measured parameters to the field scale due to the high heterogeneity of the material. Alterations in consumption patterns in both quantity and product categories, as exemplified by the increased demand for disposable single-use packaging in the Covid-19 pandemic (Correa et al 2022 ), and initiatives of separation, recovery, and treatment (Kavazanjian 2006 ; Mondelli et al 2022 ) directly affect the waste stream sent to landfills. During and after landfilling activities, the physical properties of MSW, including particle size, density, porosity, moisture content, and degree of saturation, change as its components degrade and liquid and gaseous products are generated.…”