The smuggled waste was seized, with four suspects nabbed, as part of a nationwide crackdown launched in June 2020.
It would take a storage yard as big as five football fields to store the solid waste, said Miao Bin, a customs official, on Monday.
The waste, declared as iron ore fines, was intercepted during an inspection after customs officials became suspicious due to its pungent smell and sent the item for further lab analysis in March 2020.
The waste was returned on seven ships over a course of five months starting October 2020.
China banned all imports of solid waste effective Jan. 1, with the dumping, stacking and disposal of waste products from overseas on Chinese territory also outlawed.
The country began importing solid waste as a source of raw materials in the 1980s, and for years it has been the world's largest importer.
With growing public awareness of environmental protection and the country's transition to greener economic growth, China started phasing out imports of solid waste in 2017. - Xinhua