The Mountain Cement Company in Laramie has agreed to put a filter on one of its kilns as part of a lawsuit settlement with environmental groups. The cement company, the Sierra Club and the Biodiversity Conservation Alliance presented a settlement on Wednesday to Federal Judge Clarence A. Brimmer. A trial had started Monday in Brimmer’s court over the environmental groups’ claims that one of the cement company’s kilns violated air quality regulations.  The company maintains that its operations have not been in violation of air-quality standards. A lawyer for the company says company officials were considering installing the new filtration system regardless of the lawsuit.