The company, controlled by executive chairman Lee Koh Yong and his family, is working with at least one adviser on the sale and could close the deal as early as this month, the sources said, declining to be identified as the information is confidential.
Final bidders for 800 Super include Australia's Macquarie Asset Management and KKR, which funded 800 Super's 2019 management-led buyout from the local bourse and owns a minority stake in the company, the sources said.
KKR and Macquarie declined to comment. 800 Super did not immediately respond to a request for comment.
KKR helped finance the Lee family to take back control of 800 Super by delisting it from the Singapore Exchange's Catalist board. The delisting valued 800 Super at S$161 million ($117 million).
800 Super has since expanded, clinching a 10-year contract for waste collection and transportation in one of the three zones in Phnom Penh City, Cambodia, in January last year, according to a media release at the time.
Established in 1986, 800 Super started as a traditional rubbish collector. It now uses a fleet of electrical vehicle trucks to collect waste and its current services range from cleaning and conservancy to horticultural services, according to its website.
Its clients include Changi Airport Group and Marina Bay Sands, the website shows.
The company also operates facilities that include a biomass plant which generates two million kilowatt-hours of renewable electricity monthly.
($1 = 1.3770 Singapore dollars)
(Reporting by Kane Wu in Hong Kong and Yantoultra Ngui in Singapore; editing by Jason Neely)
By Kane Wu and Yantoultra Ngui