Composting is not a glamorous process, but it is a necessity for recycling organic waste and preserving natural resources. And the market is operating at an increasingly industrial scale as demand rises. City officials and municipalities are particularly attracted to the environmental and cost benefits provided by taking material to a composting facility instead of a landfill. At these facilities, maximizing the decomposition process is crucial to success, and accelerating microbial activity to get material broken down in an efficient manner is top priority.
“The goal is to reuse and recycle a product that was once landfilled and had no value,” says Ted Dirkx, recycling solutions specialist for Vermeer. “It’s turning a low-value item into a high value item; it alleviates air pollution and water pollution from the waste stream. It also takes waste away from the landfill and improves overall soil quality.”
Stacked for success
In today’s composting facilities, there are typically two stacking methods utilized for decomposition – windrow and continuous stack. Windrows have long been the industry standard, as it exposes more material to air and sunlight. However, the perks are becoming more noticeable for those operators who have chosen to use the continuous stack method.
According to Dirkx, a major benefit of continuous stacking is optimized space usage. With windrows, adequate space is needed in between each row to be fully effective. As composting grows in popularity, existing pads will be pressed for space and could face trouble accommodating all of the windrows.
“The windrows may expose more material for better air flow, but more frequent turning can be accomplished easily with the right tools when using a continuous stack. For instance, Vermeer manufactures a compost turner with an elevating face that tears apart the material as it is lifted and re-stacked for thorough aeration,” Dirkx says. “You are taking away that extra space between the windrows and you have a pile that is 40 to 50 percent more efficient in the use of space and can better hold moisture.”
Organized planning is required for any transition from windrows to the continuous stack method, as the level of transportation needed is significantly greater in windrow stacking. With windrows, the material must be meticulously placed in long narrow rows until cured, then moved to a screening area. With continuous stacking, all of the material can be turned across the site throughout the compost process, thus reducing time needed for the loader moving material.
The pad for the compost facility can also be a major influencer on the choice of the stacking method. For facility managers with engineered and finished pads, or solid rock pads, continuous stacking is highly efficient and cost effective when it comes to space.
“When facilities start to look at the cost of concrete for additional windrows, continuous stack becomes highly appealing,” Dirkx says. “When determining facility size and stacking method, people need to think about material flow and project into the future. If you figure those numbers, then you can calculate space you’ll likely need in five years. Today they may be able to fit a windrow, but what about down the line? It may be easier to just start with a continuous method than have to adjust later.”
Dirkx offers a few additional tools and tips for operators to ensure success in the composting industry. A temperature gauge is a must-have, as it is a strong indicator of microbial activity in the pile. A watering system at the facility to help motivate decomposition can also be a necessity depending on the climate.
He adds that geographic and seasonal factors should definitely be accounted for. “There’s no perfect way to compost and no single type of compost. Each compost facility has its own characteristics and it’s definitely dictated by what raw materials are available. With that, operators need to be forward-thinking and determine if using a more space-efficient method is better for them as the industry grows in popularity.”