The Brazilian water and wastewater firm will use the proceeds of some US$8mn to reinforce its cash flow.
Under a Bolsonaro government, development bank BNDES will focus more on drawing up projects rather than financing.
The future of the project was already uncertain as mayor-elect Claudia Sheinbaum has expressed her opposition to continuing with construction of the plant.
The country's water regulator is investigating both the fails in Antofagasta's wastewater treatment system as well as the potable water cuts that resulted from these incidents.
The online procedure to submit and approve water concessions and permits was supposed to go into effect on October 15.
The ultra-right wing Brazilian candidate said he will use his tenure as president to conclude unfinished infrastructure projects.
There is expected to be more private sector participation in the industry , but challenges remain.
Civil society and academic groups argue that a new procedure implemented by water authority Conagua, which enables the issue of water concessions and permits online, is an attempt to privatize water resources.
The federal government offered US$19mn to finance projects to improve the state of the Atuel river, which is the focus of a dispute between Mendoza and La Pampa provinces.