The lumpy, ground-up food scraps that cover the bottom of a trash barrel in the basement of UMass Lowell's Fox Hall is what David Cash calls 58 pounds of "awesomeness." Once it's picked up by Casella Waste Systems' collection truck, this seemingly yucky brown substance becomes part of the company's composting operation, which turns a range of waste products, from paper fiber to ash to food wastes, into fertilization and landscaping products.