Sembcorp, which is 49.3% owned by Singapore's state investor Temasek Holdings, has hired HSBC (HSBA.L) to run the sale of SembWaste, according to the sources.
First-round of non-binding bids are due by early June, said one of the sources, declining to be named as the matter is private.
Last year, SembWaste's earnings before interest, taxes, depreciation, and amortization was S$50 million ($37.75 million), one of the sources added.
Last year, Singapore's asset manager Keppel consortium bought a 80% stake in environmental services firm 800 Super Holdings for S$304 million.
SembWaste is one of three public waste collectors appointed by Singapore's National Environment Agency to provide waste and recyclable collection services to residential, schools and trade premises in the city-state, according to its website.