What is the lecture mainly about?

Listen to part of a lecture in an environmental engineering class.
    Professor:
    At the end of yesterday’s class, we were discussing landfills and the hundreds of millions of tons of everyday garbage which are deposited into them each year in the United States. It’s a growing problem! Quite simply, we are running out of space to put our garbage. And this is especially true for solid organic waste: food scraps from home or food processing plants, waste from farms, that sort of thing. Did you know that two thirds of the waste sitting in our landfills is organic material? We have government recycling programs for materials like plastics, glass, and metal, yet widespread solutions to organic waste materials haven’t really been addressed in the United States. I think this is just asking for trouble in the future. So today I want to talk about a technology that offers a potential solution to the problem—Anaerobic Phased Solids digestion, or APS digestion. First of all, does anyone know what anaerobic means? Anyone?