Ames-based r-pipe, a startup company that converts recycled plastic pop bottles into concrete-based sewer pipes, received the top prize Thursday in the John Pappajohn Iowa Business Plan Competition, The Des Moines Register reported. The company plans to use the money to expand its manufacturing process. The other two top winners recognized during a luncheon yesterday at Drake University were Memcine Pharmaceuticals Inc., an Iowa City biotechnology firm that enhances the effectiveness of vaccines (second place, $15,000); and ScoutPro Inc., an Ames company that developed a database for farmers  (third place, $10,000). The competition has awarded more than $400,000 to entrepreneurs in the past eight years.