Waste Management said Wednesday that 650 corporate employees -- most of them in Houston -- took the company up on its voluntary buyout program. The company has been seeking to cut costs and in August launched offered buyouts to some employees. Net income adjusted for what the company said were one-time charges of $66 million related to the restructuring, and $69 million for divestitures in Puerto Rico, was $336 million or 72 cents per diluted share.