Composting equipment advances: transforming green waste

RockRoadRecycle staff writer

The composting of green waste and materials is being increasingly undertaken in order to help decompose organic substances, converting the material into a stable, plant friendly, beneficial and high quality humus product. The ideal process is efficient, quick and low emissions being essentially accomplished by shredding, mixing and (where required) screening a blend that is as free as possible from contaminants or materials that are hard to break down — all being optimized for the rotting process.  The rotting process itself is essential to the production of good compost. Post treatment screening and wind sifting further help ensure that the compost has a homogenous particle size and is free of contaminants.

In order to ensure that the material for composting is of a high quality and reduced to a size to enable further treatment, a number of companies have invested in the development of equipment and systems used in producing a high value product. What is interesting is that although the production of compost is quite a simple process, the latest developments from manufacturers enable a variety of organic materials to be recycled and turned into compost of the highest quality.

Green Mountain Technologies

One company at the forefront of composting systems and technology is Green Mountain Technologies, which has been dedicated to helping organizations reduce their environmental footprint, save money and produce high quality compost since 1992.  The company is committed to making composting an approachable, affordable and successful undertaking for organizations of any size.  This is accomplished through innovative design coupled with industry experience and ongoing R&D.  The company states that there is very high demand for different approaches to composting.  With this in mind, it has developed a comprehensive product line that includes sophisticated large-scale technologies for bio solids, windrows, ASP solutions, cutting edge software and probes, as well as some of the most popular in-vessel systems in the U.S.


German company Doppstadt traces its history back to 1965 when Werner Doppstadt founded an agricultural company in Velbert. Today it is considered to be a leader in the development of environmental technology for processing various materials such as waste wood, garbage, industrial waste, bio waste, excavated earth and green waste.  The company now offers one the largest ranges and variety of equipment, all designed to provide high performance and low energy consumption with maximum environmental friendliness.

The Doppstadt equipment range for composting includes mobile and static recycling machines for chipping, crushing, grinding, mixing, separating, screening, shredding, sorting, washing and wind-sifting of materials. The range includes shredders, trommel screens, star and flatbed screeners, sifters, mixing plants, washing plants and conveying systems.  

Transforming green waste

Highlighting how Doppstadt equipment is able to transform green waste through composting into a valuable resource is a recent project in Japan.  Here a DW 306 Ceron Type B pre shredder, a AK 640 VE fine shredding system and an SST 725 trommel screen have been combined to provide homogeneous, high quality and metal-free material to be used for thermic recycling purposes.


The equipment transforms the input material in four stages. Following the pre and fine shredding steps, metallic contaminants are removed and the material is separated into fine, finished and oversized fractions. The oversized grain is automatically circulated back into the fine shredding process until it meets the requirements of the finished product. If there is no need to run through the entire process chain, the Doppstadt plant can used for partial processing.

The DW 306 Ceron Type B pre shredder receives the input material from a re-handling excavator for the coarse shredding procedure. Mixed fractions are then conveyed to the AK 640 VE where fine shredding takes place. Enroute, an overhead magnetic system separates ferriferous contaminants from the wood with the procedure being repeated before the material enters the screening process.

The SST 725 trommel screen finally takes care of the proper granularity of the material, where it screens out the fine fraction. Oversized particles are automatically transported back to the fine shredding process to be processed one more time. This recirculation process only ends when the entire material fits the size requirements of the finished product.


Another company, which has developed composting expertise through its multifaceted equipment lines, is Austrian company Komptech. The company is now considered to be a leading international technology supplier of machinery and systems for the mechanical and mechanical-biological treatment of solid waste and for the treatment of biomass as a renewable energy source. The product range includes over 30 different types of machines that cover all key process steps in modern waste handling: namely shredding, separation and biological treatment.

For shredding and separation shredding in composting to produce the right particle size, Komptech produces low-speed and high-speed machines. Both types can be adjusted to output the desired particle size using the appropriate screen baskets and teeth. They can be enclosed or open air, depending on the input material and local conditions. Cleaning and mixing is accomplished via drum screens, star screens and disc separators.

Differentiating its offering from many of its competitors, Komptech also supplies equipment and solutions for windrow composting. This is undertaken during the layered build-up with a wheel loader and homogenized in subsequent mixing with a turner. The input material and associated limiting factors also decide whether the rotting process is undertaken closed — in an indoor part of the system — or open as windrow composting. The first phase of the process often takes place in a closed system with ventilation and outlet air treatment.

Turning compost improves ventilation, enables re-watering and ensures mixing of the different rotting areas in the windrow. The process is generally complete after six to 12 weeks. To attain a product of uniform particle size and to separate off any contaminants still present, the compost is screened. Komptech has a wide range of mobile and stationary drum and star screening machines for this process. The particle size produced is based on the intended use, ranging from coarse compost fractions for agriculture to finely screened material for mixing into garden and potting soil. Screening after composting generates a usable fraction and a screen overflow. The overflow can be run through a wind sifter to remove the light components and then used as structure fill, or it can be used as biomass fuel once the stones have been removed.

High end organics material prepping is also gaining importance, given the strict requirements of natural fertilizer laws and other quality guidelines. It is believed that going forward, only high quality compost or fermented products will be marketable. One major factor in achieving this is the removal of contaminants and foreign matter, which unfortunately continue to find their way into the organic waste stream — with plastic, glass and metal being the major culprits. This has given rise to some quite rigid limit values, which place high demands on feedstock preparation. Komptech now offers a range of machines ideally configured to deal with these issues.

One of the most interesting new machines for organic waste prepping from Komptech is the Metalfex non-ferrous metal separator, which greatly improves product quality at the end of the process chain with an optional ferrous separator also being available. Komptech has also recently updated its screening offering with the new Nemus 3000, a drum screener that has been designed for low maintenance and service friendliness. Longer discharge belts and the ability to use screen drums from competitor machines are further benefits of this highly practical machine.


The Shred-Tech Corporation designs and manufactures a large number of shredding and recycling systems. Headquartered in Cambridge, Ontario, Canada, Shred-Tech began production in the late 1970s, producing stationary double shaft shredders for a wide range of manufacturing and plant-based applications. By the middle of the next decade, Shred-Tech had developed one of the world’s first mobile shredding trucks designed to shred confidential office paper and documents on-site.

Fast forward 40 years — Shred-Tech now has well over 6,000 shredding and recycling systems installed worldwide and is recognized globally for its products as well as  its commitment to engineering, innovation and quality. With shredders in daily use around the world, servicing over 31 countries, Shred-Tech equipment is helping customers reduce costs, generate revenue and protect the environment.

Shred-Tech’s composting equipment line is designed to meet regulatory safety and material handling requirements. Shred-Tech® engineers are experienced at designing turnkey solutions to match each material handling and processing challenge. The company’s versatile line of compost shredding equipment ensures that a shredding and recycling solution can be engineered to meet specific application requirements. Options such as automated material handling, nitrogen blanketing, explosion proofing, sterilization systems and screening equipment can then be selected and matched to the application.


Central Iowa-headquartered Vermeer equipment is aimed at maximizing the world’s resources, with some of the company’s latest developments targeting the recycling and biofuel production markets. Vermeer equipment has led the way into these new industries with organic recycling equipment that processes organic waste quickly and efficiently, so it can be turned into useful end products.

Designed with innovations that help improve productivity, streamline maintenance and protect operators, Vermeer compost turners, horizontal grinders, tub grinders and trommel screens are built to last, and are fully supported with parts and service. The very latest development from Vermeer is its fully tracked CT718 compost turner — recently developed in response to composting being such an important aspect of waste management throughout the world.

Vermeer compost turners introduce oxygen into the compost pile, helping to speed the decomposition process. Vermeer compost equipment is designed to process up to 4,000 cubic yards (3058.2m3) of compost per hour depending on the type and size of the turner. Drum style windrow turners feature a horizontal steel drum with flails that aerate the compost windrow.

The new CT718 compost turner is equipped with full-length steel tracks, an option best suited for rough and muddy ground conditions. The new full track option is one of four drive systems available for the CT718. Also offered are two wheel drive, four wheel drive and two wheel plus two short tracks drive system. “We’ve added a full track option at the request of our customers,” Jeff Bradley, product manager for recycling and forestry equipment at Vermeer, explained. “The composting industry is growing worldwide and compost turners are one of the most efficient ways of ensuring that material gets the proper amount of oxygen. The full track option will give facilities with rugged or wet ground conditions a more effective option.”

The Vermeer CT718 compost turner is efficient and highly productive at turning windrows up to 18 feet (5.5m) wide. The compost turner uses a mechanical belt-drive system and a Flexxaire fan that automatically adjusts based on temperature to help maximize performance. An optimized drum design with long flails ensures proper aeration while minimizing material drag and providing protection to the drum skin. The operator-controlled rear curtain also aids with controlling material deflection.

The comfortable operator’s cab of the CT718 compost turner features programmable, preset controls that allow the user to adjust height with a single touch and a control display that shows the sides and rear of the machine through mounted cameras. With a low machine height of just 12.5 feet (3.8m) and folding ladder, the CT718 compost turner is easy to transport between locations. Additional options for the CT718 compost turner include hard surface flails and a spray bar attachment.

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