Republic Services Inc. is adding 72 compressed natural gas (CNG) waste and recycling collection vehicles to its fleet in the St. Louis region.

The Phoenix-based Republic said in a news release it is investing nearly $25 million in the natural gas vehicles, bringing its 2012 investment in the area to nearly $45 million. In May the company committed about $19 million to an upgrade of two area recycling centers that will triple Republic’s recycling capacity in St. Louis.

The new CNG vehicles will replace older diesel models. Republic serves more than than 200,000 households and 27,000 businesses in the St. Louis region.

The company plans to operate nearly 80 CNG waste and recycling trucks in the St. Louis area by the end of the year.

Earlier this week Republic announced the addition of CNG vehicles in York, Pa., and Austin, Texas.