Urban sewage sludge stabilization by alkalization-composting-vermicomposting process: Crop-livestock residue use

Waste management practices are vital for human health and the environment in a world where natural resources stress is expected to increase with the growth of population. Our study aimed to evaluate the potential use of crop-livestock residue as a bulking agent associated with the ideal level of hyd...

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Published in:	PloS one Vol. 18; no. 9; p. e0289362
Main Authors:	Floriano da Silva, Luiz Carlos, Vinhas Ítavo, Luís Carlos, Martins Santos, Ricardo, Brandão Ferreira Ítavo, Camila Celeste, Zirondi Longhini, Vanessa, Menezes Dias, Alexandre, dos Santos Difante, Gelson, Moreira Arcanjo, Angelo Herbet, Santos Santana, Juliana Caroline, Gurgel, Antonio Leandro Chaves, de Oliveira Scarpino van Cleef, Flavia
Format:	Journal Article
Language:	English
Published:	San Francisco Public Library of Science 07-09-2023 Public Library of Science (PLoS)
Subjects:	Agricultural wastes Alkalizing Bagasse Biology and Life Sciences Chromium Composting Copper Crop residues Crops Ecology and Environmental Sciences Eggs Engineering and Technology Evaluation Fruits Heavy metals Livestock Management Manures Medicine and Health Sciences Metal concentrations Molybdenum Natural resources Physical Sciences Population studies Refuse and refuse disposal Residues Sewage Sewage sludge Sludge Stabilization Sugarcane Survival Toxicity Urban areas Vermicomposting Waste management Worms Brazil
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Summary:	Waste management practices are vital for human health and the environment in a world where natural resources stress is expected to increase with the growth of population. Our study aimed to evaluate the potential use of crop-livestock residue as a bulking agent associated with the ideal level of hydrated lime for the stabilization and sanitization of urban sewage sludge through the alkalization-composting process. Therefore, we determined the alkalization efficiency on the heavy metal concentration in urban sewage sludge, quantified the viable eggs of helminths in pure and alkalized sludge, and measured the rate of earthworms (Eisenia fetida) surviving in the vermicomposting process using different levels of alkalized urban sewage sludge associated with crop-livestock residue. Four sequential trials were carried out in a completely randomized design with three replicates. The lime alkalization reduced the levels of Ba, As, Pb, Cu, Cr, Mo, Ni, and Zn compared to the pure urban sewage sludge. Using 30% w/w of lime in the urban sewage sludge (SS-30) for composting process reduced the viable helminth eggs by 71, 72, and 69% for sugarcane bagasse (Saccharum officinarum; SB), fresh chopped Napier-grass (Pennisetum purpureum; NG), and bovine ruminal content (BR), respectively. The ideal level of hydrated lime for stabilization and sanitization of urban sewage sludge was found to be 30%, which was able to reduce the heavy metals. The residues have the potential as a bulking agent for the composting of urban sewage sludge when associated with alkalization. The lime alkalization decreases the total number of helminth eggs and the number of viable eggs. The possibility of starting a vermicomposting using the mixtures is promising, evidenced by the earthworm survival in composting urban sewage sludge mixed with crop-livestock residues after 45 days of composting. The earthworm survival is maintained by an association of at least 80% of the crop-livestock residues.
Bibliography:	ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 Competing Interests: The authors declared that there are no conflicting interests.
ISSN:	1932-6203 1932-6203
DOI:	10.1371/journal.pone.0289362