According to Brian Schellati, Van Dyk Recycling Solution’s director of business development, “Not only does equipment have its own required routine maintenance, but how the equipment is laid out will determine material handling logistics. How easily materials flow through a plant from tip floor to processing, to product storage, to baling can make or break a plant’s chance at success.”
Caterpillar application specialists always work with the mantra of “task, tool, machine,” notes Tom Griffith, machine/application specialist for waste.
A material recovery facility (MRF) needs to be designed to handle inbound, recovery, and outbound loads to meet specific production requirements and efficiencies while keeping costs low, he adds.
One important design factor: inbound storage space adequate for tonnage per day as well as peaks, says Griffith. “Peak outbound—depending on who owns trucking—sometimes is not the same as peak inbound. Inbound stockpile needs to be close to whatever machine is feeding the sorting lines,” he adds.
Be it a wheel loader, rubber-tired excavator/material handler, or excavator, the stockpile should be situated so that the machine loading the feed lines has minimal movement and can pick, sort, discard, and feed the lines for needed production per hour, notes Griffith.
“At the same time, there needs to be room for discarded materials—non-recyclables—that the sorting machine will place in a separate pile to be pushed to outbound haul vehicles to take to the landfill with minimal movement and distance,” he adds.
Griffith notes that for quick cycles and support work, consider: ceiling height, free space with few if any obstacles, easy access in and out to discard bunkers, conveyor line cleanup, width and length of load-out hole, and type of load out, such as below grade, half separation, or same level.
Depending on the required production per hour, the work tool and machine needs to be right-sized to handle such system factors as in-bound, outbound, sort and discard, and line feed, notes Griffith.
Factors to consider: tonnage per hour, peak volumes and tonnages, and what support is required, with other activities performed by the machine. Other considerations in equipping primary and secondary machines: required production per to meet sort line numbers, material type, type of end load, and what is the floor like.
Other points of consideration in matching work tools and a machine include possible storage, high-lift capabilities for higher stockpiling by the wheel loader, or a larger tool/front end for the wheeled hex or excavator, he says.
Of Caterpillar’s technologies, the waste industry utilizes VisionLink and Product Link telematics for fuel and machine utilization; Payload Control System to help achieve immediate and consistent outbound weights, and traction control to lower tire costs, fuel use, and floor wear.
Caterpillar’s XE wheel loaders are designed so that MRF and other operators can derive more efficient use of power to ground with lower costs for fuel, tires, and maintenance and increased production, Griffith says. The same is the case with the HEX hybrid, except for tire costs, he adds.
Consider staff, operators, and maintenance workers in the design process, says Griffith. “What is their experience level? Are they trained? More than once a year? Do they understand the objective? Do they listen? Are they allowed to add input? Do operators perform walkarounds and submit daily inspections sheets? Do maintenance personnel review the sheets? Are the machines downed properly for oil changes, preventative and required maintenance?”
Also, regarding managers: “Do they attend operator and maintenance training so that everyone is on the same page? Do they listen? Are they involved, or is going to the tip floor a necessary evil? Do they manage without micro-managing?”
Outside specialists can offer efficiency assessments, operator training, right sizing of tools and machines, safety analyses, and other services to help reduce costs, Griffith says.
Evan Williams, design project manager for Cambridge Companies, points out that, ultimately, those running a MRF operation must have an idea of how they want to operate and staff it before design finalization, as the design helps achieve goals set for throughput, staffing, operational costs, maintenance practices, and safety standards.
The arrangement of the equipment is important to minimize unnecessary conveyors, all of which need maintenance, says Williams. “Careful selection of equipment to best return the desired results in performance is critical,” he says. “If low upfront costs are most important, the system will likely use more hand sorting, requiring higher staffing levels. Conversely, use of more automated sorting processes like optical sorters will minimize staffing requirements.
“Equipment choices drive how the facility works,” he continues. “Whether a compactor is used for residue or if that material is ejected to a bunker will affect facility operations.”
After choosing equipment critical to the MRF, start the layout of the building and surrounding site which enable the equipment to operate and be maintained as efficiently as possible, says Williams.
One key consideration is whether the provided storage space for incoming material is sufficient to efficiently handle material stream fluctuations, Williams says. “If the tipping area is too small, either the trucks have to wait in line for floor space or the loaders stack up material, making access to the system in-feeds difficult,” he adds.
A building should be large and tall enough so all areas have easy access for ongoing maintenance, as well as give managers the ability to add or modify equipment without radical building changes, says Williams. “Keeping the employee break areas, restrooms, and liquid stations close to their work areas helps decrease the amount of time employees spend walking around the facility and increasing efficiency,” he says.
Marathon Equipment, part of Environmental Solutions Group, offers new technologies such as the Torxx Kinetic Pulverizer and the Burcell System designed to “revolutionize the processing of materials as a feedstock for energy recovery and other valorization processes,” notes James Robbins director, stationary products. “These technologies are a key part of helping companies divert materials from the landfill while reducing their overall carbon footprint.”
He adds that his company often works with existing buildings. “The equipment layout has to be adapted to squeeze everything in considering existing constraints,” says Robbins.
Material Handling Machines
One key piece of equipment is the material handler. Builtrite Handlers & Attachments manufacturers a stationary electric material handler, which works much like an excavator in that they are designed to be quick and offer an even flow on the conveyor belt, says Uwe Kausch, senior vice president of sales and marketing.
The stationary material handler also offers safety benefits in that it is not moving around the facility, which also results in more productive time, Kausch says.
Kausch cites a recent installation of a stationary electric material handler at “an extremely busy” Rumpke MRF in Cincinnati, OH.
The material handler, placed high on a concrete pedestal, offers the facility more working space and the swivel bearing enables an operator to work continuously in any direction, Kausch points out.
The high cab placement offers the operator more visibility when loading onto a conveyor, Kausch says, adding that items such as tires and propane tanks can be easily plucked out of the wastestream with the material handler’s grapple.
Builtrite’s newest model has 35 feet of reach, a 100-hp motor, and an orange peel grapple. A newer application for the stationery electric is the ability to tamp the waste down. “We see more potential with these stationery electrics in the MRF facilities,” says Kausch, adding that it is favored for not having the same emissions as diesel units.
Rutger Zweers, sales manager of STADLER America LLC, says that efficiency is a key design element for MRF’s that want to ensure the highest productivity, lowest downtime, and the purest recovery of recyclables.
“Efficiency is required throughout all operational aspects of the plant,” says Zweers. “It starts at the tipping floor, with effective inbound material handling and consistent feeding of material onto the system. This, along with efficient metering, provides optimal presentation of material to the pre-sorters, subsequent screening, and separation equipment, resulting in the greatest possible productivity, contamination removal, and recovery of recyclables.”
Matthew Everhart, CEO, points out the increasing utilization of their Ballistic Separator, a STADLER innovation, for the effective separation of two-dimensional (2D), three-dimensional (3D), and fines materials.
The STADLER Ballistic Separator is available in numerous versions, each designed specifically for the application or customer need. It can effectively be utilized as a single or multi-decked screen for paper and cardboard (OCC) separation.
STADLER America LLC introduced this separation technology—developed and widely utilized in Europe—into the US marketplace in 2007. Today, there are more than 20 STADLER Ballistic Separators installed in North America.
“Very low-maintenance costs, high sorting efficiency, and flexibility of utilization for almost any type of material stream are the hallmarks of the Ballistic Separator,” says Everhart. “The resulting streams from STADLER’s more than 1,000 Ballistic installations are much more precisely sorted than the streams coming from conventional disc or star screens, providing better material purity without all the manual sorting labor required previously.”
Resulting 2D materials, such as fiber, can now easily be introduced to additional processing equipment without manual intervention or fear of material contamination; 3D materials can now also be sorted more effectively due to the vastly reduced amounts of fiber and plastic film in this stream.
“STADLER developed the Ballistic Screen to provide the most highly effective separation of 2D versus 3D materials. This effectiveness—coupled with the ability to remove fines from the stream—ensures that subsequent sorting equipment, such as optical units, are also more effective, ultimately resulting in cleaner end products and higher percent of material recovery.
Proper separation by material size and shape is key in how materials are presented to the final sorting stages in a MRF, Zweers point out. “Our trommel screens and Ballistic Separators are designed to provide highly effective separation with minimal power requirements, low maintenance costs, and increased operational hours. They also entirely eliminate the troublesome issues of material wrapping around shafts and stars,” he says.
Footprint
In designing a MRF to optimize the footprint, Waste Management aims to streamline the process as much as possible as it impacts facility siting, traffic floor, and material flow, says Brent Bell, vice president, recycling, for Waste Management. “Our goal is to eliminate any double handling of the materials and make the flow from delivery to loading on outbound shipments as smooth as possible,” he adds.
Building dimensions—including height—are key to a successful MRF design, says Schellati. “If not given the proper space, plant operations will greatly suffer as a result of difficult material handling and inability to easily access equipment for maintenance,” he adds.
When it comes to MRF footprint design, “bigger is typically better,” says Williams, adding that ample height accommodates screen packages and other equipment getting larger and taller. “It is good practice to ensure the processing area is at least 40 feet tall.”
Griffith agrees a MRF should be designed for future growth. Design the tip floor to handle peak periods of inbound material and enough storage space to accommodate unsynchronized inbound/outbound truck routing, he says. The footprint should also be designed with safety in mind, accounting for the interaction of mobile equipment, inbound/outbound loads, and people.
Additionally, the layout of sorting lines, inbound/outbound bunkers and interior/exterior outbound waste, and ease of line maintenance should be considered in footprint, Griffith says. “Since down time is serious consideration for MRF operations, needing to enlarge tipping areas or bale storage areas is never advisable,” he says, adding the building structure should be designed to accommodate future growth. “We recommend sizing those spaces for the upper end of 10- or 20-year projections.”
Automation
MRF managers continue to contemplate the balance between human labor and automation. The cost of automated equipment is coming down, while labor costs rise, points out Kim James, Marketing Communications Director, Vecoplan LLC.
Electing to go with an automated versus manual MRF comes down to available capital and volume of material, explains Doug Sites, environmental product manager for the McLanahan Corporation. Automation makes sense for those who are running 50- to 70-ton-an hour plants, he says.
For both single-stream and multi-stream types of MRFs, there are always ways to fully automate the processing, notes Schellati, echoing that financial viability is a deciding factor.
Williams believes there is a good balance to be struck between automatic and manual sorters. In achieving that balance, manual sorting is effective for the pre-sort line. For sorting out ferrous and aluminum, automated magnets and the eddy current are effective.
Properly designed screens also are quite effective for sorting out paper and fiber from within a single-stream system, says Williams, adding there needs to be staff on hand to keep the automated equipment operating at peak efficiency.
The McLanahan Corporation is preparing to introduce a piece of equipment that helps separate commodities from film without human interaction. The equipment is currently in the pilot stage with much success, notes Sites.
The machine is compact and can be retrofitted into an existing facility, he says. It addresses industry safety concerns, which he points out focus on the uncertainties of materials on the front end of an operation before the material is separated out.
At Waste Management, “we prefer as much automated sorting as possible, but we have to balance that against the cost of the automation,” says Bell. “Volumes in each market will dictate equipment sizing. We don’t want to overcapitalize a site if the population base isn’t there to support the necessary volumes. We ideally want to be able to process all the materials that are received within 24 hours.”
Conveyance
The conveyance system plays a key role in doing that. Vecoplan has a new modular material conveyance handling design to enable MRF operations the flexibility to expand or retract as needed, says James.
For example, a system originally designed for 15 tons an hour that has to expand to meet a 25-tons-an-hour demand would in the past mean that an operation would have to remove most of its conveyance system or add an entire line, James notes.
Modular technology offers the flexibility to enable an operation to splice a belt, add length on to it and expand to make it adaptable for new configurations, he adds.
Live Floors
Flexibility also is desirable with live floors. Hallco Industries recently released an accelerator unit used in conjunction with the company’s hydraulic drive units for unloading materials and moving bulk materials on a live floor.
It allows the floor to switch from a three-stroke with eject to a two-stroke with eject and move up to 30% faster, notes Ricardo Aguinaga, regional sales manager.
While the majority of the company’s end users still deal with household MSW, “we are starting to see a little bit more of an uptick in industrial waste, such as manufacturing waste,” says Aguinaga.
The live floors are scalable and can be designed for MRF systems that are highly abrasive or host significant weights or volumes or require extra-long or extra wide space, he adds. “The most efficient use of the floors is if MRF operators have the ability to coordinate with their deliveries. If that is not an option, and if they are at the will of the delivery and having to make a decision on the fly, the best approach is to design it to accept more volume in. It can be used as a staging floor as opposed to just an immediate feed floor.”
The live floors also have been designed for automatic sorting “where they know how many yards per hour they can run through,” says Aguinaga. “They use a laser eye to control the flow of the material onto the floor, so it’s just being loaded and the machine is automatically calculating how fast or slow it needs to run to keep the material flow going.”
There also have been installations of live floors used for post-sort, Aguinaga points out. “After it’s sorted into the different materials, it’s delivered onto the floor, and the floor is used to move that into the next stage—whether it’s going to be sorted, compacted, or shredded.”
The KEITH WALKING FLOOR system is a horizontal “moving floor” conveyor comprised of a series of floor slats powered by a hydraulic drive. As the floor cycles through its phases, material is conveyed or unloaded.
In MRFs, KEITH WALKING FLOOR conveyors are typically installed in receiving bins that store sorted recyclables. When needed, the system conveys the material to a takeaway conveyor, which feeds it to a baler.
It also is installed at the tipping floor, where material is fed into the MRF for sorting and processing. Bins with KEITH WALKING FLOOR conveyors located below the sorting lines automate the unloading process, “resulting in a more efficient and safer method than using a loader to feed the takeaway conveyor,” says Rick Wilson, sales engineer.
Wilson points out KEITH WALKING FLOOR equipment is designed to have a positive impact on the safety and efficiency of MRF design. “Using a front end loader to push recyclables through can increase the risk of equipment/pedestrian accidents and can cause exhaust issues for employees on the pick lines,” he adds.
Systems are engineered to nearly any size requirements. They are also able to move more abrasive materials such as green waste and construction debris. They also can store and convey a variety of recyclables, including paper, cardboard, and plastic.
Balers
Catawba Baler & Equipment recently introduced its new Gold Rush series of Free Jam Two-Ram Balers to address industry safety concerns. “Ever since the beginning of two rams, there’s been no way to clear a jam out of the baler with the exception of sending a man or men inside the baler to clear the jam,” notes Mark McDonald, the company’s president and owner. “Since 1990, there have been more than 20 deaths in two-ram balers in the recycling industry when the machines jam and an employee is sent inside the baler to clear the jam. Clearing jams sometimes take 20 minutes and can sometimes take five days.”
A death may result from safety switches being bypassed when an employee enters a baler to clear a jam, which can trigger a photo eye and the machine starts to cycle, McDonald points out.
The CB&E Free Jam Two-Ram Baler is designed, so there is no need to enter the machine. The jam is cleared with the push of a button. The machine addresses all solid waste streams, including plastics, polymers, paper, soft metals, and RDF trash. It can be custom-designed to fit any layout, McDonald says. The baler also offers the redundancy of twin motors for times when one goes down, enabling MRF operations to continue.
The company designed the software to be user-friendly by anyone in a MRF operation, McDonald adds. Safety benefits also are derived in preventative maintenance activities. “Having the free jam door allows access inside the machine for maintenance,” he says. “Many injuries happen with folks inside the machine handling common maintenance. This machine has a huge door that opens to allow an individual a quick escape route.
“You never know if you’re welding or cutting if a fire might start and you need to get out of that machine quickly,” he adds. “In a conventional two-ram baler, the only way you can go is up. With this baler, you can go sideways out at ground level out of the machine or up. In the instance of an emergency, that could mean the difference between life and death.”
Single Stream
Waste operations are on an ongoing mission to determine which is better: single-stream or multi-stream collections, and MRF designs must accommodate. “There is a lot of consideration for multi-stream facilities versus single stream,” says Robbins. “The interest in recovering and capturing value from material that has traditionally been landfilled is increasing. Automation comes with volume—while a small facility with a relatively clean stream of recyclables may be able to get by with a small manual sort system, automation is a necessity in processing larger volumes. It is not practical to staff a large system with enough sorters to do everything. Automation is required to do the heavy lifting of sortation.”
At Waste Management MRFs, the decision to go with a single-stream, versus multi- stream will be dictated by the collection systems in place, notes Bell, adding that both models perform well.
It’s critical to realize the basic differences between single stream material and mixed waste, says Schellati.
Material density is one difference as it relates to volume or the space it takes up both on the tip floor and as it works its way through the separation system, he says. “The three major differences between the two are the amount of organic or food waste, oversized bulky materials, and the lack of fiber typically found in mixed waste as opposed to single stream,” says Schellati.
Mixed waste also is typically bagged material as opposed to being loose like single-stream recyclables, meaning that the front end of a mixed waste MRF has to be very different than a single-stream MRF, Schellati notes. “Once the oversized bulky waste and organic/food waste is removed, then the two types of systems can have somewhat similar downstream processing techniques,” he adds.
Schellati points out that because mixed waste has a much higher amount of organics, it has potential tip floor odor issues that are not of concern in single-stream MRFs.
In MRFs with manual sorting, the ratio of sorters per ton does not differ too much between single-stream and mixed waste MRFs, says Schellati. “Single-stream MRFs tend to have slightly more due to the amount of fiber quality control required,” he says. “We also try to minimize mixed waste MRF pre-sorting because most of the material is bagged and it can be a major safety issue to have humans hand-sorting mixed waste.
In processing single-stream materials, it is imperative that plants are designed and technology capable of processing no less than one ton of material per sort line employee, points out John Green, president of Green Machine, which manufactures recycling systems. “Systems that reach two tons per man per hour are the most profitable.”
Single-stream processing systems “are far from dead,” notes Green. “We have processing plants paying more than $20 per ton for incoming material and that still make a profit. We do see trends heading back to dirty MSW MRFs, but utilizing better technologies.”
Green contends that the “mistake has been in designing the mega-mixed waste MRF that is supposed to reach ‘zero’ disposal. Those plants are labor-dependent, have too low throughput, and produce contaminated materials. “High-volume, less costly, and labor-hungry plants offering more than 30% diversion rates provide a sweet spot where both the equipment vendor and operator make money,” he adds.
Green Machine has developed a new MSW mixed waste dirty MRF processing system technology that processes up to 60 tons per hour and offers recovery diversion rates of 30%, with a system cost of less than $2 million with 12 employees, says Green.
End users are asking for MRF designs that can handle multiple streams “in the sense of not having dual stream where there are multiple lines that are designed for different types of materials, but in making one single line that can handle single-stream commercial waste or MSW,” says Sites.
“That’s a very complicated task, but I think with today, when we see commodity prices all over the board, the MRF operators—when they invest in a MRF—have to have the flexibility that if a market changes, they can change the material they can bring in and how they process it.”
One of the biggest factors moving forward in MRF design is giving the end users the ability to run multiple types of materials with one system, says Sites. “We’ve built this screen, built OCC screens, but we try to push our customers towards trommels and ballistic separators, because it gives us more flexibility for more of the materials,” says Sites.
Efficiency
To achieve optimal efficiency, “the overall goal would be to recover the most materials possible with the highest degree of purity for the lowest overall processing cost,” says Robbins.
In both types of MRFs, efficiency is mainly determined by system throughput/capacity in tons per hour, product recovery and product quality, says Schellati. “System uptime is critical and is something that has to be factored into overall system capacity,” he adds.
For MRF efficiencies, Waste Management focuses on the ability to maintain consistent system utilization with limited production interruptions. “We also would like to have the machinery perform the bulk of the material separation with the sorter only performing QC operations,” notes Bell.
To design a MRF for optimal efficiency, one must focus on equipment design and ideal arrangements of that equipment, says Williams, adding that equipment design is a compromise involving site size, layout, building, budget, and incoming material stream.
Maximizing efficiency starts with the equipment design as a standalone item, he says. “Make that layout and system as efficient as possible for the allowed budget. Pay attention to critical considerations like where clean loads will be unloaded to be directly fed to the balers, or whether there is a way to directly load the in-feed conveyor if the metering bin is offline.”
Companies also should focus on getting the plastic film material and anything that will wrap on the screen shaft off before the material gets to the screens, says Jeff Eriks, Cambridge’s chief business development officer.
Republic Services’ 110,000-square-foot recycling center during final construction
Safety
While operations continuously seek to address reduction of labor costs, it is increased safety for personnel that serves as the biggest issue in a MRF, Sites says.
“The key to developing newer, more advanced MRFs or the MRFs of the future is adding more safety features,” he says, adding that efficiencies already exist because of automation.
Robbins points out that ergonomics for employees and compliance with all ANSI and other applicable standards should be a top priority.
Bell concurs. Good ergonomics for the sorters also limits injuries from over-exertion or overreach, he says.
In Waste Management MRF design, traffic flow is a primary safety consideration, says Bell, adding is it important to “limit the number of vehicles delivering from crossing paths with other vehicles or other moving equipment if possible.”
A lockout, tagout system helps eliminate the line being started until lockout is removed, says Eriks.
Other safety considerations include additional access to perform the necessary machine maintenance.
Zweers outlines the factors that are considered for utmost safety in a MRF design:
- The system design and implementation needs to obey the latest system-built standards such as OSHA and ANSI. Aspects to consider: staircase inclination, railing height, and fall hazards inside equipment.
- Increased visibility to most—if not all—manual sorters positioned throughout the plant from a central point, commonly the location of Main Control Panel (MCC) and typically achieved by maintaining a single level platform.
- Keeping personnel off the ground and reducing the interplay between rolling stock and personnel by having appropriate service and access.
- Providing proper accessibility to work on equipment, safe working conditions inside or on top of equipment. “This is one key aspect of the Stadler Ballistic Separator: to provide a very level working area to walk on and minimize the need for extensive use of box cutters or other cutting tools as commonly required on shaft-equipped screens,” says Zweers.
A safety program should be designed to meet all needs of the MRF, notes Griffith, and include daily, weekly and monthly meetings to build upon employees’ knowledge levels. Safety training designed to meet all employees’ responsibilities should take place quarterly, semi-annually, and annually.
MRF safety measures should include marked and regulated safety walkways, properly-maintained mobile and stationary equipment, safety features on mobile equipment such as backup cameras, personal protective equipment worn by all employees and anyone on tip floor, such as drivers and laborers.
“Is the safety program a forward-thinking program, or a program that just ‘checks the box,'” asks Griffith. “Do managers take it seriously?”
Visitors need to be kept off of process lines and the working floor, Williams points out, adding that raised catwalks, viewing platforms, or learning centers with cameras will limit the exposure of visitors to injury.
Keeping foot traffic off the floors is key to safety in all areas: process, bale storage, and tipping floors, Eriks says.
To address the issue of minimizing opportunities for personnel and motorized vehicles and equipment to cross paths, Cambridge has designed on several projects elevated walkway connections from the employee break areas to the processing area, protecting employees from vehicle strikes.
“Additionally, proper design of sorting stations and their ergonomics is important to minimize repetitive stress injuries,” says Williams. Loading docks should be equipped with dock locks that ensure trucks are held in position until fork trucks are out of the trailers, he adds.
A MRF should have adequate lighting throughout the facility, especially in equipment maintenance areas for safe working conditions, says Williams.
LED lighting is starting to show up in new and retrofit MRF construction as the lights become more affordable and offer better lighting while using less energy, says Eriks. “Also, solar energy generation pays back in many markets now with the power companies,” he says. “There are many credits available and the units themselves produce more energy than ever before.”
Employee health and air quality is another important factor in MRF design and in a safe work environment, notes Williams. “It is important to ensure that you are keeping your employees hydrated in the summer and warm in the winter,” he says. “Air quality can be improved through the use of dust collection systems or mist systems to collect or knock down airborne debris. This, along with air movement within the facility, will help improve air quality.”
Dust control also keeps the facility much cleaner and helps reduce fire-related issues, notes Eriks.
Odor and Dust Control
NCM Odor Control offers dust control systems for processing paper, cardboards, and other recyclable material. The company also offers odor control for dirty MRFs.
NCM Odor Control also does health risk assessment studies based on the amount of particulates within the atmosphere, as well as tracer studies to show if there is migrating dust, how far the dust is traveling, and at what concentration it is hitting the receptors in the field, notes John O’Brien, vice president of operations.
“We’re also doing a lot of design work with the negative air systems they tend to use in some of these buildings for dust control,” he adds. “We can do a model study that shows where and how the air is moving within the building in direct relationship to that negative air system, and know what is being captured and what’s not being captured. It helps with the design work on the front end, as opposed to redesign work on the back end.”
OSHA regulations regarding dust as a visual impairment is a driving factor for the use of dust control systems, O’Brien points out. “A lot of companies say they have a lot of dust that’s dropping on stairs and creating a slick environment,” he adds. “They want to contain the dust. A dust control system provides direct misting of the material being processed on the front end, so by the time it reaches the back end where it’s weighed and baled up, it’s dry.”
Another benefit of the misting system is that it keeps working environments cooler, which is appreciated in warmer climates, O’Brien points out.
The machine is normally placed within the sprinkler room and remote control is used to control the zones. For an extra safety measure, a loader operator does not have to exit the cab to turn the system on to mist, says O’Brien. That also provides increased time efficiencies in that there is no delay in loading the material onto the conveyor belt, he adds.
The remote control also acts to conserve water, O’Brien points out. “There’s not an abundance of water out there, so a lot of these sites are handicapped as to how much water they can use per day, such as in California,” he says. “Operators have total control: they only run it when they need to.”
Dust control also minimizes maintenance, O’Brien says. “It dramatically decreases the amount of time people have to spend cleaning up at the end of the shift,” he says. “When they shut the machines down, they’ve got to dust everything off, which creates dust as you move dust around.”
Michael Beckley, president of Ecolo, says MRF design and technology are issues frequently discussed with the end users of his company’s odor control products. “Odor is one of those nuisance issues that surface, and commonly need to be addressed in one manner or another when the MRF is located within close proximity to a community.
“From our experience, when a MRF is in the design stages, the type of wastestream, footprint, operating objectives, and location all play critical roles in the factors determining the scope of an odor management plan,” he adds.
To that end, Beckley says he’s seen MRFs adopt a variety of odor technology ranging from carbon, biofiltration, and scrubbing techniques in closed cell environments, to the most conventional type of odor control, including fixed nozzle high pressure and mid pressure misting of deodorizers with nozzles positioned in ceilings, around bay doors, and around the perimeter of properties.
Ecolo manufactures installs and services these types of misting systems, putting an emphasis on using the correct chemistry, says Beckley. “One of the keys to effective odor control misting is the selection of the right deodorizer, application intensity and proper equipment maintenance,” he says, adding the company now produces more than 60 different formulas to suit a wide range of specific odor application requirements.
Ecolo recently launched a line of oscillating high-pressure misting cannons that come as self-contained trailers or portable wheel and skid-mount units. The units are designed to combine the benefits of misting odor control solution at 1,000 psi for increased dispersion and droplet optimization with high-power oscillating fans for significant property coverage.
Positive movement of material is key to MRF efficiency.
When not treating the air, Ecolo recommends the use of its new foam-based biological accelerant and contact deodorizer product, BioStreme 111F, on all hard surfaces and standing piles of separated recyclables and organics, including leachate collection.
“BioStreme can be a very effective part of a closing regime, treating piles and floors before buildings are closed up for the night or weekends,” says Beckley. “The product works at the microbiological level by using a liquid non-bacteria nutrient formulation that encourages a proliferation of non-odor producing bacteria. The product is applied with or without foam, which helps track coverage, and can last for days when not interrupted.”
Dust Control Technology offers dust suppression and odor control products. The OdorBoss is new technology engineered to disperse odor control agents using water as the delivery vehicle. “Inspired by the DustBoss line of dust suppression equipment, the OdorBoss uses a powerful fan to propel the treatment into the air or onto surfaces,” notes President Laura Stiverson.
The equipment is designed to minimally impact the overall footprint of a facility. “With dust suppression, many industries looked to the DustBoss for that alternative to massive collection systems built into the infrastructure,” notes Stiverson. “While powerful, these are much more permanent solutions. Conversely, the DustBoss can be added to an existing fugitive dust plan with less disruption.”
With MRF facilities, a common tactic addressing both dust and odor is lining the ceiling with mounted sprinklers, she points out.
OdorBoss and DustBoss, nozzles are concentrated at one point, designed to make maintenance and replacing clogged nozzles safer and easier.
Like the DustBoss, the OdorBoss can adjust to an evolving footprint. The device is mounted on towable trailer fitted with standard 500-gallon (1,893 L) water tank. Coverage and chemical usage vary depending on odor intensity.
“We recommend starting with a thousand-to-one water-to-chemical ratio, and adjusting as necessary,” says Stiverson. “That ratio requires about a quarter of a gallon—or one liter—of additive over eight hours, meaning workers will fill the tank once per shift at a usage rate of just 0.5 to 0.75 gallons of water per minute.”
While dust and odor may seem unrelated, suppression follows the same principles of matching water droplet size to the target, says Stiverson. “To atomize a substance is to convert it into very fine particles or droplets. Atomized mist technology uses special atomizing nozzles to fracture the stream into millions of fine droplets of water,” she points out.
“Different tasks require different sized droplets. The OdorBoss G [OB-G], for example, achieves droplets about twice the size of a human red blood, or 15 microns, the optimum size to attach to odor vapor.”
Atomized mist is an efficient solution for odor and dust with more conservative water usage, says Stiverson, adding that with MRF workers already having so much on their plate, odor and dust control helps make their jobs easier.
Buffalo Turbine has augmented its gas and diesel Monsoon line with its BT-KB5 electronic fuel injected (EFI) tow-behind turbine debris blower, designed for fuel savings and featuring a wireless start/stop function. The company’s most requested models are oscillating units, notes Brian Singer, marketing manager. The units are relatively small, taking up a small footprint in the operation, he adds.
The BT-KB5 EFI tow-behind turbine blower features a Kohler 26.5-hp EFI engine, designed to be up to 20% more fuel efficient than current carbureted engines.
The micron size of the water used by the Monsoon unit traps the dust and bonds with it, bringing in down, which enables MRF workers to breath healthier air, says Singer.
To optimize odor control, Buffalo Turbine works with Benzaco Scientific, which provides input regarding optimal odor control solutions.
Good control of dust and odors makes for happy neighbors.
Laura Haupert, director of research and development for OMI Industries, says it’s not enough to eliminate foul odors in a MRF. “Today’s eco-friendly industrial odor-control solutions should be non-toxic for the safety of industrial employees, the public, and the environment,” she says. “In fact, they should be readily biodegradable—at least 60 to 100% in 28 days—which have shown to be much safer for the environment.”
Haupert says Ecosorb is designed to be an eco-friendly odor abatement solution used in MRFs, among other industrial applications, and has been tested against EPA guidelines, receiving the “safest possible classification.”
She adds, “It avoids the use of odor masking agents, which can be toxic and has been scientifically proven to be safe for the environment. Ecosorb solutions contains no hazardous VOCs and are safe for both humans and the environment.”
Wastestreams
Not only is the way waste collection changing, but its makeup and some of its end markets are changing as well, such as with plastics in response to such factors as lower petroleum prices. Steel has been projected to go down this year as well, Vecoplan’s James points out.
All wastestreams are being examined to potentially pull out materials of value, says Schellati. “The hot topic in the market is how to process and divert more usable material from residential MSW, dry commercial MSW and commercial food waste,” he says.
New technology includes glass cleanup systems in single-stream MRFs, says Schellati. “The dirty glass fraction from single-stream recyclables has always been a major problem for single-stream MRF owners,” says Schellati.
Van Dyk has provided solutions in two Northeast US locations, and two more expected to come online early in 2016. “Everybody is trying to make sure they’re accounting for the possibility of one bin collection,” notes James.
“We see single stream continue to develop,” he adds, pointing out Dallas, TX, as an example, with a single-stream MRF now under construction.
MRF operators want flexibility in their system design to be able to address similar changes down the road if they want to, James says.
As for wastestreams going forward, Zweers says that in addition to the common dry single stream, “we see the market move to process a mixed municipal solid wastestream. The implementation of this kind of processing may depend from state to state, and the location conditions like cost of current hauling and disposal, diversion targets and guidelines, and privatization.”
In assessing the direction of the future wastestream, Zweers says he strongly believes that it depends on the project location, current infrastructure in place with regards to hauling and curbside separation of recyclables, as well as city or state guidelines to increase recovery rates from landfills. “Ultimately, a need or requirement to divert more materials from landfill will be a key driver to process more wastestreams,” he says. “The location of the project, composition of the waste, and its available markets will provide foundations for these projects to become feasible.
“In addition to the sorting and separation of valuable recyclable commodities, the allowance and use of an engineered fuel—as commonly accepted and done throughout Europe—would allow non- or low-value recyclable materials to find another use such as at cement plants or alternative waste conversion technologies to either make a liquid fuel or heat or power generation.”
The engineered fuel can either be sold for use offsite or serve as part of a more comprehensive and advanced waste management system when use onsite for power or steam generation, says Zweers.
Wastestreams MRF operators will see going forward include a demand to process more streams than conventional so-called clean recyclables, says Robbins. “These include various organic waste streams, and also things such as fiber that may have been contaminated by contact with other waste,” he adds.
Sites says the wave of the future is that MSW is going to have to address organics and higher diversion rates. “In California, you can’t send organics to the landfill anymore, and I think that’s something we’re going to see across the nation,” he says. “Also, we’re looking at higher diversion rates with more recycling.”
One of the biggest challenges affiliated with automation is that various markets request different commodities, notes Sites. “With paper on the West Coast, they don’t care if it’s a mixed paper or a white paper,” he adds. “On the East Coast, we’re seeing they want a white paper or brown paper or mixed paper products.”
Flexibility is the most important factor for MRFs, notes Sites.
McLanahan’s optical sorters are pre-programmed to pull out different products, he says. “If they want to pull out white paper, it pulls out white paper. If they want to pull out leftover OCC in the stream, we can do that. 3D fraction, any grade of plastic, Tetra Pak—all of that is built into the system.”
The optical sorters also can be programmed to pull out new products that have a different genetic makeup as far as the near infrared sensor can detect, says Sites.
In discussions with leading MRF managers about waste streams, Griffith notes single streams operate most efficiently with recoverables from “clean routes”—little mixture of materials with liquids and undesirable wastes.
Dirty MRFs endeavor to utilize routes that can offer the best return of recoverable materials, says Griffith, adding that recovery from automated lines is only as good as the material it is processing. “Some stations will have multi lined/bunkered facilities that will handle MSW, light C&D, and green waste,” he says, adding that he sees an amplification of a trend in the US toward recovering compostable materials and materials that can be used for fuels, anaerobic digestion, and RDF.”
Looking ahead to anticipated wastestreams, “we will certainly continue with the streams of materials we receive today, but we have to adapt to the customer supply demands while balancing it with potential end market demands,” notes Waste Management’s Bell. “Over the past few years, this has become important as many end markets that used to buy material either have stopped accepting them or are in such a financial state that we are unsure of their future long-term viability. A program can only be as good as the markets that are supporting it.”
To access additional case studies and in-depth reporting, check out the June edition of MSW Management.
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