 ELGIN, Ill.--BUSINESS WIRE--Heritage-Crystal Clean, Inc. Nasdaq: HCCI, a leading provider of parts cleaning, used oil re-refining, and hazardous and non-hazardous waste services primarily focused on small and mid-sized customers, today announced results for the first quarter which ended March 27, 2021. First Quarter Review Revenue for the first quarter of 2021 was 105.4 million compared to 107.3 million for the same quarter of 2020, a decrease of 1.8. Overall Operating Margin jumped to 2 