UK recycling firm Viridor is to be sold to US-based private equity firm Kohlberg Kravis Roberts & Co (KKR) for £4.2 billion ($4.76bn). Parent company Pennon Group said the valuation recognised Viridor’s “strong, diversified and complementary” UK recycling and residual waste capabilities, along with its expected growth opportunities. Viridor’s revenue increased by 8.5 per cent…