The transaction, valued at some 500mn reais (US$302mn), was structured and financed by investment banking group BTG Pactual, paper Valor Econômico reported.
The two companies' combined revenues are estimated at 1.1bn reais.
Estre Ambiental operates seven waste management centers in Brazil and also offers recycling, soil and water remediation, hazardous industrial waste disposal and environmental consultancy services.
Cavo Serviços e Saneamento offers urban waste collection and cleaning services, with a 38% share in São Paulo urban waste concessionaire Loga. The firm also has medical waste treatment and landfill operations.