- Volume - When waste is burned the volume reduction is drastic. As much as 90%. A pile of garbage the size of a minivan would be reduced following processing to the size of a large duffel bag. The ash and anything left over can then be landfilled without taking up as much space. Yes, landfilled; but keep reading as to why these remnants of the process are different.
Same chamber after processing
A loaded chamber of garbage (approx. 3-4 tons)- Safety - The ash that is left over from the thermal process is inert. All of the organic substances are burned away leaving carbon (ash) and compounds that cannot be burned like metal or minerals. This remaining ash is as safe as the ash that is left over from a campfire just that there will be objects left in it like springs from a mattress or the occasional toilet (seriously, that is something that gets thrown in a landfill but now that it has been thermally processed it is sterile and is just a clean piece of pottery).
- Fuel Usage - The waste stream is its own fuel source. Pound for pound, plastic has just as much calorific value as crude oil (calorific value = how much heat is given off when burned, wood has a certain calorific value but plastic is higher). It requires a small amount of fuel to start the process but in continuous systems this amount is insignificant. Even batch systems have a low fuel usage because the fuel used to start the process is only on for 10-15 minutes of a full 24 hour cycle.
- Recycling - There are two things that remain after processing: ash and un-burned compounds, mostly metal. I imagine that a sorter at a recycling facility would love to sort through a pile of ash for recyclables after all of the baby diapers have been burned away. A simple pass under a magnetic belt extracts any ferrous metal that can then be sold to metal scrap yards for a premium because it will be stripped of any organics, paints, plastics, foams, etc. Non-ferrous metals can be sorted using known sorting methods also and yield the same results. What about plastics?
Remnants of a burn process - Energy - As mentioned, the waste stream is its own fuel source. The thermal process is a positive net gain process meaning the the process produces more heat than it needs for volume reduction. This heat can be captured using standard waste heat recovery systems and produce energy. Plastics are becoming increasingly more prevalent in society and by so also in waste streams. Although most of these plastics are recyclable by sorting, this process is extremely time consuming and no matter how much a sorting facility may claim to save, they are throwing most of it back into the landfill. This plastic is just as valuable as an energy source; it is made from crude oil. Plastics are only one of the items found in waste streams. Construction debris usually has a lot of wood.
- Sorting Not Required - It doesn't matter what is processed. When designing a system for municipal waste it is pretty much understood that pretty much anything will end up in the burn chamber. This included large cylinders of propane (these are exciting), medical waste, roadkill, lead acid batteries, car engines (even full of oil), waste oil, electronic waste, etc. All of these things would shut down a landfill operation because of safety concerns. Even though attempts are made to have certain waste streams processed using certain controlled methods regulators and designers know that municipal waste is the cornucopia of waste streams. Therefore the system is designed for worst case scenarios and made to handle these sort of hiccups.
- Process Options - Continuous or Batch? That depend upon waste stream amount, waste stream type, post processing requirements, and location. Either way the system provided will meet any requirement of waste processing.
- Cost - What is the cost of starting a new landfill or expanding an existing landfill? What about the cost to maintain the landfill after it has been capped? We know that the biggest problem with getting people in board with thermal waste processing is not the costs of the system; it is the revenue lost for the waste management companies. If you were going to loose your job you would be angry too. Check out Disadvantages to Landfilling Waste and look through some of the health concerns. The waste management companies will still get to process waste but now they don't have to constantly scare away wildlife, bury the waste on a daily basis, stink up the neighborhood, and leave an empty, useless plot of land behind.
Please contact us for information on improving your waste processing. Also ask us about other options on post processing (energy production, recycling, pyrolosis, etc)