EXHIBIT 32.1

CERTIFICATION PURSUANT TO
18 U.S.C. SECTION 1350
AS ADOPTED PURSUANT TO
SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

In connection with the Quarterly Report of Fortistar Sustainable Solutions Corp. (the “Company”) on Form 10-Q for the quarterly period ended March 31, 2021, as filed with the Securities and Exchange Commission (the “Report”), I, Nadeem Nisar , Chief Executive Officer of the Company, certify, pursuant to 18 U.S.C. §1350, as adopted pursuant to §906 of the Sarbanes-Oxley Act of 2002, that, to the best of my knowledge:

 
1.
The Report fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934; and

 
2.
The information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of the Company.

Dated: July 23, 2021

 
/s/ Nadeem Nisar
 
Nadeem Nisar
 
Chief Executive Officer
 
(Principal Executive Officer)