 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 second quarter which ended June 19, 2021. Second Quarter Review Revenue for the second quarter of 2021 was 117.3 million compared to 79.5 million for the same quarter of 2020, an increase of 47.4. Overall Operating Margin jumped t 