Only between 20 and 50 per cent of the households participating in a trial of Hong Kong’s new pay-as-you-throw waste tax were using the designated bags to dispose of rubbish, environment minister Tse Chin-wan has said, a week after the pilot scheme began. Residents had complained about the size of the bags and the inconvenience of recycling food waste, Tse told a TVB programme on Sunday, as he defended the government’s decision to implement the charging scheme amid a flailing economy. The Municipal Solid Waste Charging scheme, which was originally meant to take effect this month, requires resi…