Development of wet mechanochemical treatment for the use of WTP sludge as raw material for the production of controlled-release fertilizers

• Grant number: 23/09673-0
• Support Opportunities: Scholarships in Brazil - Support Program for Fixating Young Doctors
• Start date: August 01, 2023
• End date: March 18, 2024
• Field of knowledge: Engineering - Materials and Metallurgical Engineering - Nonmetallic Materials
• Agreement: CNPq
• Principal Investigator: Cauê Ribeiro de Oliveira
• Grantee: Roger Borges
• Host Institution: Embrapa Instrumentação Agropecuária. Empresa Brasileira de Pesquisa Agropecuária (EMBRAPA). Ministério da Agricultura, Pecuária e Abastecimento (Brasil). São Carlos , SP, Brazil
• Associated research grant: 23/01549-8 - Development of wet mechanochemical treatment for the use of WTP sludge as raw material for the production of controlled-release fertilizers, AP.R

Abstract

Sludge from water treatment stations - WTP - has characteristics that make its destination a challenge. The variability of composition, the low content of organic matter and, especially, the high content of aluminum salts considerably limit its direct application on agricultural soils, being a solution already studied for sludge from sewage treatment plants (STPs), which have higher organic matter content. However, its mineral structure could, in principle, be the basis for the production of pellets that would act as soil conditioners or as adjuvants for fertilizer-controlled release systems, an alternative that would enable the high volume consumption of the residue. Thus, simple and alternative technological routes that immobilize the aluminum salts in nonsoluble structures allied to formulation technologies, to avoid subsequent immobilization effects of the essential fertilizer phosphate (P), could enable conditions for agricultural use of this waste. Therefore, it is proposed to develop, from representative WTP sludge from SABESP production, a wet mechanochemical route to produce zeolitic concentrates from reactions with KOH, which can be formulated as extruded fertilizer granules using urea-plasticized starch and thus compose a slow-release fertilizer. Standardized laboratory, greenhouse, and field tests will be conducted to evaluate the agronomic efficiency of the fertilizers. Thus, it is expected that the integration of different strategies will provide greater agronomic efficiency and competitiveness to the reuse of these residues.