The effect of stabilization on the utilization of municipal sewage sludge as a soil amendment
- Authors: Černe, Marko , Palčić, Igor , Pasković, Igor , Major, Nikola , Romić, Marija , Filipović, Vilim , Igrc, Marina Diana , Perčin, Aleksandra , Goreta Ban, Smiljana , Zorko, Benjamin , Vodenik, Branko , Glavič Cindro, Denis , Milačič, Radmila , Heath, David John , Ban, Dean
- Date: 2019
- Type: Text , Journal article
- Relation: Waste Management Vol. 94, no. (2019), p. 27-38
- Full Text: false
- Reviewed:
- Description: Stabilization procedures affect nutrient and inorganic contaminant concentrations.•Anaerobic sludge has the highest levels of metals and radionuclides.•High P and N contents in sludge are a measure of its potential as a fertilizer.•Adsorption of metals and radionuclides to sludge biomass increases with nutrient content.•Soil amendment with sewage sludge is a promising strategy for nutrient recovery. This study assesses the potential use of different types of stabilized sewage sludge as a soil amendment by considering their physicochemical characteristics, nutritional status, and their trace metal and radionuclide content. The concentrations of trace metals and radionuclides were determined using ICP-OES and gamma-ray spectrometry, respectively. For determining nutritional status and chemical characterization, this study followed standard ISO-recommended procedures. Data analysis revealed that anaerobic sludge contains higher concentrations of Cr, Hg, and Ni compared to aerobic and non-biologically stabilized sludge. A similar observation was observed in the case of 226Ra, 210Pb, 228Ra, and 228Th. Furthermore, the high levels of P and N in aerobic sludge suggest that biologically stabilized sludge has the potential to be a good fertilizer. In addition, the study finds strong evidence that nutrients are involved in the adsorption of metals and radionuclides onto sludge biomass. Overall, eight of the nine studied sludge samples are safe for agricultural use since the concentrations of trace metals fall well below the limits set by Croatian legislation (NN 38/08). In addition, the levels of radionuclides do not pose a radiological risk. This means that soil conditioning with sewage sludge remains a viable strategy for nutrient recovery from municipal waste, although long-term impact assessments of repeated applications are necessary.
Characterization of organic compounds in biochars derived from municipal solid waste
- Authors: Taherymoosavi, Sarasadat , Verheyen, Vincent , Munroe, Paul , Joseph, Stephen , Reynolds, Alicia
- Date: 2017
- Type: Text , Journal article
- Relation: Waste Management Vol. 67, no. (2017), p. 131-142
- Full Text: false
- Reviewed:
- Description: Municipal solid waste (MSW) generation has been growing in many countries, which has led to numerous environmental problems. Converting MSW into a valuable biochar-based by-product can manage waste and, possibly, improve soil fertility, depending on the soil properties. In this study, MSW-based biochars, collected from domestic waste materials and kerbsides in two Sydney's regions, were composted and pyrolysed at 450 °C, 550 °C and 650 °C. The characteristics of the organic components and their interactions with mineral phases were investigated using a range of analytical techniques, with special attention given to polycyclic aromatic hydrocarbons and heavy metal concentrations. The MSW biochar prepared at 450 °C contained the most complex organic compounds. The highest concentration of fixed C, indicating the stability of biochar, was detected in the high-temperature-biochar. Microscopic analysis showed development of pores and migration of mineral phases, mainly Ca/P/O-rich phases, into the micro-pores and Si/Al/O-rich phases on the surface of the biochar in the MSW biochar produced at 550 °C. Amalgamation of organic phases with mineral compounds was observed, at higher pyrolysis temperatures, indicating chemical reactions between these two phases at 650 °C. XPS analysis showed the main changes occurred in C and N bonds. During heat treatment, N-C/C=N functionalities decomposed and oxidized N configurations, mainly pyridine-N-oxide groups, were formed. The majority of the dissolved organic carbon fraction in both MSW biochar produced at 450 °C and 550 °C was in the form of building blocks, whereas LMW acids was the main fraction in high-temperature-biochar (59.9%). © 2017 Elsevier Ltd