The city of Des Moines’ wastewater treatment plant will be one of the first in the nation to implement energy efficiency measures as part of an effort to reduce energy costs, the Iowa Office of Energy Independence said Thursday. An $83,225 grant awarded by that agency and the American Recovery and Reinvestment Act of 2009 will help the plant implement a software tracking program designed to monitor the performance of motors, pumps and blowers. The project, which is slated to begin in early 2011, is expected to cut the plant’s energy costs by up to 20 percent, or $41,584, a year.