Ask the Grinder Guy – April 2014

ask-the-grinder-guyHey Grinder Guy, do I need a windrow turner?

If you are new to the composting industry, you are probably wondering what, when and why compost operations use windrow turners. Whether you are composting yard waste, food waste or sludge, a windrow turner can be an essential part of composting material but not necessary in every case.

Composting requires water and oxygen in an open air environment. We can get technical and discuss carbon and nitrogen levels, but basically, you need water and oxygen.

A windrow turner is used to aerate a compost pile. That can include mixing  materials, applying liquids and generally loosening the material in a windrow. The more oxygen available to the materials, the more they heat up and start the compost- ing process. It’s pretty simple, just like the leaf pile in your back yard.

In general, in a food waste or municipal sludge application, it would be very difficult to convince me of a reason not to use a windrow turner. The mixing action of a turner and the ability to provide oxygen to all the material in the com- post pile is something you cannot do efficiently with a wheel loader. Having the ability to break up heavier materials like sludges, and being  able to break apart food waste particles, is just something you cannot do with a wheel loader. These heavier, wetter materials tend to block any airflow through the windrow. The more airflow, the more oxygen. The hotter the pile, the more composting of materials. This means a faster compost process as well. If you are short on site space, the faster the composting, the more material you can compost.

A windrow turner provides adequate airflow into the materials and in- creases the porosity of the pile by loosening the materials. Without the oxygen, piles will turn anaerobic. This creates enough odor that neighbors in the next county will be complaining.

When it comes to yard waste composting, the materials are generally loose to begin with, so turning with a loader is generally sufficient. The problem comes when you get to 25,000-30,000 ton per year. With  that  volume of material, you need to speed up the process and compost faster. With that much material, you can keep a windrow turner busy and do a much better job of aerating the windrows than with a wheel loader. This will help speed  up the process and produce compost in probably half the time as just bucket turning it with a wheel loader. This will also save you a lot of site space because a wheel loader needs to get in between the piles to turn the windrows, while a straddle Windrow  Turner doesn’t. Piles can run together at the edges with some Windrow Turners.

So do you need a Windrow Turner?

  • What type of materials are you composting?
  • What volume of materials are you composting?
  • What kind of site space do you have?
  • Do you need to apply water or liquids to your windrows?

These questions should answer everything for you. There  are different types of Windrow  Turners. There is the pull behind type, which is towed by a tractor for example. This style operates along- side the tractor instead of atop a windrow like the straddle type. The straddle type Windrow Turners are able to turn the material in larger windrows and turn heavier loads. The pull behind type is fine for small windrows and startup operations.

So what do you look for in a Windrow Turner?

  • Define your volumes and decide which type will work best;
  • If you are short on site space, look for a unit that can turn windrows that are inches apart. This saves an incredible amount of site space;
  • Look for one that can apply liquids while you are turning. Yard waste com- post will compost much more quickly when you are adding water to them
  • If you are composting sludges and food waste, look for a turner with some kind of cab air fil- tration system for the op- erator. Ammonia and oth- er chemicals build up in windrows and the air quality inside the opera- tor cab can be affected;
  • Match the windrow width and height to the Windrow Turner size;
  • Look for a unit that will turn the entir; and.
  • Ask about options like scraper devices, windrow displacement and tracks or tire drive.

While this is just a general outline, it should put you on the right path to your needs.

Questions, Dave Whitelaw

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