Bootstrap Compost, a green start-up company that collects food waste from residences and light commercial operations, has started offering its services in Belmont. Clients who want to compost but don’t have the space or time receive a 5-gallon bucket that they fill up with food waste and leave outside for pickup. Bootstrap returns 5 gallons of usable compost to active subscribers every 15 weeks. Every one or two weeks, depending on the client, Bootstrap will return with a clean bucket. Rates start at $8 per week. Belmont’s pickup day will be Saturday. Employees make about 30 percent of pickups on bicycles. Bootstrap operates in 18 area communities, including Brookline, Cambridge, Newton, Watertown, and Waltham.  According to a company announcement, it has diverted more than 150,000 pounds of scrap from landfills. To sign up, go to www.bootstrapcompost.com. The company’s Twitter handle is @CompostBoston.