Chengdu Haichang Polar Ocean Park
This facility opened in 2010.
By 2011 they housed a bull walrus -- I presume this to be Badun, and he was likely present at the park's opening. In 2014 the park imported an additional pair of walruses who I have no further information on at this time.
By 2016 the 'Walrus Aquarium' exhibit had been renovated to instead feature polar bears, being renamed 'Polar Bear Aquarium'. The facility seems to have still housed a walrus up until November of 2019, but I was unable to sight any walruses in the park during 2020 -- It seems likely that they no longer house the species.