With shredders playing an increasingly crucial part in waste management and recycling facility operations, operators need to ensure these assets deliver on performance. But for equipment that was once required simply to act as a heavy-duty workhorse, today’s shredders must now demonstrate far more sophisticated performance criteria if they are to provide a true return on investment.

Here are 10 things to consider when thinking about purchasing a new shredder.

1. Define your input materials

The first component of finding the right shredder for your needs is considering the specifics of the materials you wish to shred. Assess the type and bulk density of the waste you’re handling, as well as any likely variation in this specification and the preferred in-feed method for loading the shredder. These factors will influence everything from the drive power and the the chamber dimensions to the cutter capabilities and the height of the machine. It’s also important to define the likely volume of input materials that need to be processed and at what pace, as this will shape the shredder’s throughput criteria.

As difficult as it can be to predict the future—and you don’t want to invest in too large a machine unnecessarily—it is crucial to forecast for what your needs will entail down the road. Very few organizations remain stagnant, so purchasing a shredder with additional capacity for increased volumes is often helpful, as is a shredder’s flexibility in handling different input materials with quick and simple reconfigurations. A mobile shredder will offer even further flexibility if it can be relocated around a site with ease.

2. Define the output specification

Operators must be clear on exactly what the shredder’s job will be before purchase.

Some facilities invest in shredding machinery purely to reduce the size of the bulky materials they no longer have use for and/or find difficult to store, in which case output fraction is not such a priority. Others are driven by increasing compliance requirements, which means output performance matters far more. Then there are organizations with extremely defined specifications to satisfy. If a plant is manufacturing a waste to energy fuel such as solid recovered fuel (SRF) for example, a clear calorific value and homogeneous particle size of less than 2 inches is typically desired. It is therefore important to look for a shredder with an ability to achieve the desired output specification. In an ideal world, the machine should be flexible to evolve alongside the operator’s changing needs, too. Often, this is possible thanks to just a simple screen swap.

3. Ask application-specific questions

Next, operators should ask detailed, application-specific questions to shredder manufacturers to understand the machine’s true performance capabilities. Things to consider include:

• Confidential document shredders benefit from a low-speed, high-torque design, as they can shred classified material to an agreed specification without destroying the material fiber, which helps downstream recycling.
• If shredding organic waste and packaging, operators should look for purposefully designed sealing systems that will protect the machine’s gearbox and bearings from this potentially aggressive material.
• E-scrap shredders must have an ability to liberate the various high-value composite materials “locked” in redundant electrical equipment and appliances, as well as a built-in resistance to foreign objects or unshreddables that could otherwise lead to costly downtime.

4. Stipulate safety criteria

Waste companies know industrial shredding has the potential to be a hazardous exercise, which is why manufacturers have worked to ensure equipment safety through more conscientious design.

Maintenance tasks that minimize operators’ exposure to the inner workings of the shredder, proactive diagnostic control panels that prevent the need for machine entry, and foreign object protection mechanisms that ensure equipment auto-stops when processing an unshreddable item have heightened equipment safety in recent years. Still, engineering innovation is driving even more safety benefits.

For example, low-noise shredders help protect against prolonged exposure to noise. Additionally, machines can now feature UV, infrared, heat and spark detectors to help prevent fires. Ergonomic design is even being prioritized so that personnel can service and maintain equipment quickly, safely and in an upright position without the need to hunch or over-stretch, which can lead to injury.

5. Think about the environment

Attitudes towards recycling and waste management differ significantly across the U.S. That’s why operators must prioritize their own performance criteria when investing in fit-for-purpose shredders.

This is why a number of modern machines are driven by energy-efficient electric motors composed of synchronous drives instead of diesel hydraulic drives. Not only does such technology represent far less of a fire risk, it translates to reduced energy consumption. There seems little point of transforming trash into a renewable fossil fuel substitute if the cost of the manufacturing process is harmful to the environment.

Pursuing more “green” machines also makes commercial sense, as energy-hungry shredders don’t just have a detrimental carbon impact—they can prove costly in terms of fuel consumption, too. This can limit a machine’s possible ROI.

6. Test the shredder

Identify reputable shredder manufacturers who can supply individual pieces of machinery, as well as those that can help design, source and install an entire recycling or waste management system. Whether an operator needs a complex plant or a simple waste processing line, true shredding experts will be able to help map out a turnkey solution for maximum efficiency.

Also, operators shouldn’t just trust suppliers at face value. Seeing is believing, so those involved with purchasing should speak to existing customers, and better still, request a site visit to witness a working demonstration of the equipment. The best trial of a chosen shredder requires using one’s own materials. This can offer evidence on whether the shredder can truly deliver on any promises made.

7. New vs. used

Many industrial shredders are built to last, which means that while a machine may have reached the end of its useful life in one facility, it could still have years of operational potential with another organization. This presents an attractive investment option for many businesses, especially those who can procure a high-performance used shredder for a fraction of the cost of new technology.

Some manufacturers offer shredder rebuild services, too, which can give the operator greater peace of mind regarding the ongoing condition of the equipment.

8. Other considerations

Of course, the shredder needs to fulfill the performance criteria set out for it, but wider due diligence is also important.

Users should ask the manufacturer about typical service intervals and to what extent they are likely to affect uptime, for example. Labor-intensive maintenance tasks can soon cause operational disruption, which isn’t just inconvenient, it costs money, restricts the payback period of the shredder and could even put operators’ health and safety at risk.

Think also about factors such as the cost of spare and wear parts, typical wear rates, and the availability of these crucial components. Again, this will all impact future uptime statistics and influence the shredder’s lifetime running costs.

Some suppliers take aftersales support very seriously, which means long-term ROI is far more likely. Others don’t think much beyond the initial sale of the machine, which can leave operators feeling isolated when it comes to refresher training or future process optimization.

In short, users should look for a shredder specialist that prioritizes a long-term partnership approach.

9. Ask for a project plan

While some facilities can be flexible in their lead times for a new shredder, others have to work to strict project plans. So, whether a machine is replacing incumbent technology and downtime cannot be afforded, or the commissioning timeframes risk jeopardizing the likelihood of a new plant coming online, operators should talk to the supplier about next steps and key production deadlines.

Shredders are commonly engineered to order, so a rapid turnaround is probably not possible. But a serious and engaged supplier will respect the project criteria and do what they can to keep the installation moving while communicating with the operator every step of the way.

10. Do the math

The business case for an investment in new equipment will almost always come down to the numbers. The price tag matters, of course, although different financing routes can make things more affordable for organizations that need to spread the cost. However, other metrics are also important. Calculate ongoing wear costs, as this will rapidly inflate the financial impact of the investment. Users should also think about power consumption—some electric-driven machines are now so energy-efficient that fuel savings alone accelerates the payback period. Then there’s the possible revenue that can be generated from the sale of cleanly segregated recycled products, so include these projections, too.

If there is doubt regarding the business case of investing in a machine, operators can ask the shredder supplier to help plot this out, as this exercise should be straightforward for them.

Bernhard Martinz is the president at UNTHA America. He can be contacted at bernhard.martinz@untha-america.com.

Reducing the concentration of ammonia in landfill leachate is often necessary to meet discharge permit requirements. This is true for direct discharge of treated leachate to surface waters and may be required to meet publicly owned treatment works (POTW) discharge permit standards. Ammonia reduction treatment is primarily necessary to prevent toxic impacts on aquatic life in surface waters and to reduce its toxic effects on bacteria populations used in the POTW treatment systems. Ammonia reduction can be accomplished with established wastewater treatment technologies; however, the right treatment depends on the site in question.

Factors to consider

• Ammonia and ammonium (NH₃+NH₄ as nitrogen), total Kjeldahl nitrogen (TKN = NH₃+NH₄ + organic nitrogen), and total nitrogen (TKN + nitrite-N + nitrate-N) in wastewater are all related by being different constituents of wastewater nitrogen. Each nitrogen species can be analyzed by a laboratory to determine its concentration in wastewater. POTWs can have pretreatment requirements for one or more of these nitrogen constituents, depending on their treatment methods and discharge requirements. Nitrogen is an essential nutrient used in fertilizers, but when present as ammonia, for example, nitrogen constituents can be toxic to aquatic life at low concentrations. While ammonia is toxic to aquatic life, ammonium is less toxic. Thus, it is important to know the acceptable ammonia concentration allowed in the treated leachate before choosing a treatment technology.
• pH is an important wastewater parameter for landfill leachate because pH affects the concentration of ammonia and ammonium present in the wastewater. At a constant temperature (e.g., 20°C) and at a neutral/lower pH (<7), the ionic form—ammonium (NH4)—is 100 percent present, and at a higher pH (>10) the gaseous form—ammonia (NH3)—approaches 100 percent present. Leachate, and other wastewaters that have a pH of between 7 and 11.5, have an equilibrium of ammonium and ammonia that changes with the pH (e.g., the lower the pH, the more ammonium is present; the higher the pH, the more ammonia is present at a set temperature).
• Temperature also affects the ammonium/ammonia concentration, with lower temperature leachate having lower concentrations of ammonia when compared with higher temperature wastewater at the same pH. The effect of temperature on the concentration of ammonia in leachate increases with higher leachate pH. For example, a water sample that has a pH of 9 and temperature of 40°F will have  approximately 10 percent ammonia and approximately 90 percent ammonium, whereas the same water sample (pH of 9) at 90°F will have  approximately 48 percent ammonia and 52 percent ammonium. Both water samples will have the same analytical result for total ammonia (NH3+NH4), regardless of the temperature.

Other constituents in leachate can also affect the treatment method used to reduce ammonia concentrations because certain methods are also used to treat those other constituents. For example, additional chemicals and treatment processes may be needed to treat ammonia and other constituents, compared with leachate that only requires a reduction of ammonia.

Treatment methods

Nine of the most effective treatment and/or disposal methods for leachate and other wastewaters with elevated ammonia or total nitrogen are summarized below. The type of treatment process used will depend on several factors:

• The specific nitrogen compounds (e.g., ammonia, ammonium, nitrite, nitrate and organic nitrogen) that require removal or reduction
• The initial concentrations of the nitrogen compounds in the raw leachate
• The target post-treatment concentration requirements (i.e., discharge permit standards)
• Multiple other criteria, including leachate chemistry factors mentioned previously. 

Biological treatment: Total ammonia and organic nitrogen can be converted into less toxic nitrites and nitrates (NO2 +NO3) by bacteria through microbiological degradation or “nitrification.” Nitrification of wastewater is carried out by nitrifiers, (e.g., Nitrosomonas and Nitrobacter bacteria) in an aerated, temperature- and pH-controlled bioreactor or other aeration facility. The nitrifier bacteria require oxygen and carbon as well as alkalinity for pH control. Denitrification is facilitated by denitrifying bacteria (e.g., Pseudomonas and Bacillus bacteria) in an anoxic environment that converts NO3 to nitrogen (N2) gas, which is released to the atmosphere.

Several biological treatment methods are particularly effective at removing ammonia, organic nitrogen and total nitrogen from wastewater. For example, a membrane bioreactor (MBR) uses denitrification and nitrification in the “bioreactors” to treat high ammonia concentrations (100 to 2,000 milligrams per liter [mg/L]) and organics (less than 30,000 mg/L biochemical oxygen demand (BOD)) in wastewater. The use of a membrane ultrafilter allows the MBR-treated wastewater to be discharged with minimal suspended solids. Biosolids are retained in an MBR to circulate back through the bioreactor tank(s). Another type of biological treatment is a sequencing batch reactor (SBR) that involves multi-step batch biological processes to treat high-nitrogen wastewaters. More traditional biological treatment methods, such as activated sludge, are only employed for wastewater with a low ammonia concentration (approximately 20 to 40 mg/L ammonia).

POTW discharge/hauling: If a POTW that uses biological treatment is locally available and will allow the landfill to discharge its leachate and wastewater, this option is often the least expensive. A POTW is designed to treat ammonia and other constituents that are found in leachate using the activated sludge method of treatment. However, these facilities are not usually designed to treat concentrated wastewater and the POTW will often charge the leachate generator based on the ammonia concentration, as well as the concentration of other chemicals found in leachate. If a POTW is not locally available, wastewater may be hauled to the POTW, and the leachate generator may incur higher costs.

Breakpoint chlorination: Ammonia nitrogen removal can be accomplished chemically by adding chlorine to wastewater, which causes ammonia to oxidize, primarily to nitrogen gas. This method is generally only used to “polish” effluent wastewater with lower concentrations of ammonia. The theoretical chlorine-to-ammonia ratio of 7.6:1 means that it takes 7.6 pounds of chlorine to oxidize 1 pound of ammonia. However, because other wastewater constituents are often readily oxidizable (e.g., organics), the amount of chlorine required can be significantly higher. Additional issues include the potential production of nitrogen trichloride (NCl3) gas, which is toxic and explosive, as well as increasing the concentration of total dissolved solids (TDS) and the need to control pH. Thorough mixing is critical to the effectiveness of breakpoint chlorination, as is pH control. Fifteen mg/L of alkalinity is consumed per mg/L of ammonia oxidized, so alkalinity must be monitored and added if it is not already present as a pH buffer in the wastewater.

Air and steam stripping: By raising the wastewater pH to between 10.8 and 11.5, the wastewater’s total ammonia equilibrium is driven toward 100 percent ammonia gas (NH3). The higher pH wastewater can then be passed through an air or steam stripping tower, where air or steam is forced through cascading wastewater, which causes the ammonia gas to be volatilized or “stripped” from the wastewater. Wastewaters with ammonia concentration greater than 100 mg/L usually require steam stripping; air stripping is ideally for ammonia concentrations between 10 mg/L and 100 mg/L.

Selective ion exchange: Contact with specific ion exchange media can remove ammonia, nitrite and nitrate from leachate through adsorption. One media, used to remove ammonia, is called clinoptilolite. Separate ion exchange media are used for nitrite and nitrate removal, if necessary. Significant pretreatment is required before passing leachate through the ion exchange media, including removal of total suspended solids and competing ions such as those associated with hardness, as well as aluminum and iron.

Ozone and hydrogen peroxide: Total ammonia and organic nitrogen can be removed through the advanced oxidation process of ozone oxidation and hydrogen peroxide. The ozone and hydrogen peroxide reacts to oxidize ammonia to primarily nitrogen gas. Ozone can also assist with effluent disinfection if needed. As with other oxidation processes, competing constituents that can be oxidized will increase the consumption of ozone and peroxide.

Evaporation: Heating wastewater, either with landfill gas or waste heat (e.g., enclosed flare, engine or micro-turbine exhausts) in an evaporator can convert wastewater to water vapor, thereby reducing the wastewater volume by up to 95 percent. Ammonia and other odors (e.g., from sulfides, like H2S) can be generated as part of the evaporator vapor plume. Concentrated solids resulting from the evaporation process need to be disposed of and are customarily landfilled.

Deep injection well: Wastewater may be injected into the subsurface through specially designed and permitted wells in regions where the regulatory framework supports permitting of a well and where there is appropriate geology for liquid disposal. The subsurface zone where wastewater is injected is vertically separated by impermeable formations far below the underground sources of drinking water. Special construction methods, including redundant means for environmental protection of below-ground sources of drinking water, are required. Depending on the local geology and leachate or other wastewaters considered for injection, the depth of an industrial wastewater deep injection well can generally range from 3,000 feet to greater than 12,000 feet. Geologic formations that will accept wastewater include porous sandstone and permeable carbonate formations.

Reverse osmosis (RO): The use of permeable membranes can effectively reduce nitrogen and other leachate constituents, including ammonium. The leachate to be treated is pressurized on one side of the RO membrane, and because of the membrane’s very small pore size, water molecules pass through the membrane pores leaving concentrated chemical constituents suspended in water on the other side of the membrane. The “concentrate” waste stream can be further treated using even higher-pressure membranes to decrease the concentrate volume to be disposed. Concentrate volume will vary with different leachates but generally ranges between 15 to 35 percent of the original waste stream.

A final word

Consider conducting bench-scale and pilot-scale testing for any nitrogen removal or treatment system that is feasible. If the wastewater/ leachate water quality changes, the makeup of nitrogen compounds remaining in the wastewater effluent may also change. When there are changes to the processes that generate wastewater (e.g., landfills accept new types of waste, etc.), testing the wastewater helps to identify any changes to the concentration of nitrogen compounds. Thus, necessary changes to the treatment processes, such as additional aeration or chemical additions, are easier to identify and implement.

Sam Cooke is the vice president and senior chemical engineer at SCS Engineers. He can be reached at scooke@scsengineers.com.

Over the years, Leck Waste Services, a regional refuse company based in Ivyland, Pennsylvania, has become increasingly tech savvy.

While operating the company’s collection vehicles, ranging from front loaders to fully automated collection trucks, drivers are tasked with using multiple systems, including arm-mounted digital scales designed by Eugene, Oregon-based Air-Weigh as well as fleet management software from San Diego-based Soft-Pak, which offers real-time GPS tracking, mapping, route productivity and other features for the driver. Leck Waste also uses Downers Grove, Illinois-based Dover’s 3rd Eye, a camera system that captures and documents in-cab and external events to improve safety and profitability of fleet operations.

While technology and fleet management software allow Leck Waste and other haulers to optimize routes and increase profitability, each solution comes with a price.

"We need the data and information to be able to run our business, but we need to do it in a safe way.” –Jason Leck, president and owner of Leck Waste Services.

“There’s literally no real estate left inside the truck,” says Jason Leck, president and owner of Leck Waste Services.

An industry-wide issue

Two years ago, the issue of in-cab design came up when Leck and other industry advocates, including Tony Romano of 3rd Eye, spoke on a technology panel at WasteExpo.

“In a conventional truck, there seems to be a little bit more cab space, but when you move into the cab design in a front loader or even a semi-automated or fully automated collection truck, with all the control panels that are installed inside the cab, there’s very limited space,” Leck says. “Then, when you start adding additional technology and mounting tablets and driver-facing cameras, we’re starting to fight for real estate.”

© Kzenon / stock.adobe.com

The problem, Leck says, is that each piece of technology his drivers use requires its own tablet or display screen and space to be mounted inside the cab. Not only does this pose logistical problems, it creates a safety issue. With so many different platforms operating within a truck, drivers can easily become distracted.

“Accidents typically happen when your driver has to stop what he’s doing in the process of servicing something to do something in the cab, and then he goes back to what he’s doing and starts to drive again,” Leck says. “Are we creating an issue where we require drivers to be touching or looking at tablets every time they service an account? We need the data and information to be able to run our business, but we need to do it in a safe way.”

Leck says the panel conversation at WasteExpo yielded a potential solution: The industry needs to create a standard for truck design and there needs to be collaboration between truck manufacturers and technology solutions providers to come up with a better way to implement fleet management hardware in vehicle cabs. Leck says the panel agreed that the best solution would be if an industry trade association, such as the National Waste & Recycling Association (NWRA), Washington, developed a standard for in-cab design “for how [manufacturers and software providers] share that space,” Leck says.

The panel proposed using a “central device” inside the cab to access the different applications as well as allocating one location inside the truck for the tablet “that’s already built into the dash” of the truck.

“Our thought is there is this ability for all these technologies and routing software to be utilized on one tablet in the vehicle that is designed to be placed in a certain location for the driver in a user-friendly area,” Leck says. “All the software that’s being developed should have to be able to work on that system that the driver could use. It would be cleaner, easier and safer if all those things didn’t have to be independently installed in the cab.”

A call for collaboration

Leck says while the industry recognizes there is a problem, the conversation hasn’t yielded a solution, yet. One of the challenges, he says, is getting truck manufacturers and software companies on board.

"It would be cleaner, easier and safer if all [these technologies] didn’t have to be independently installed.” –Jason Leck, president and owner of Leck Waste Services.

“They designed their product and they want to sell their products individually,” Leck says. “We want to use these products, but we have to have one universal point for everything in the truck to be displayed.”

Kirk Sander, chief of staff and vice president of safety and standards at NWRA, says the association’s safety committee is aware of the cab design issue and has been working with manufacturers on a solution. He also says the conversation around the placement of technology inside trucks opens the door to discuss other driver-related issues regarding cab layout. For example, the location of the parking brake is not always prominent enough to get the attention of younger drivers in the field, who are used to driving automatic vehicles, he says.

“I think technology is the best way to start the conversation, but I think technology it just a piece of the conversation of what the cab layout should look like,” he says.

Of the technology piece, Sander says, “This comes down to the driver experience on limiting items, such as screens and buttons. We recognize the need for a better user experience, not only to reduce distraction, but to improve efficiency and safety of our drivers.”

The author is the digital editor of Waste Today and can be reached at kmaile@gie.net.

Based on estimates from the U.S. Department of Labor’s Occupational Information Network, more than half of construction production occupations are exposed to contaminants like pollutants, gases, dust or odors at least once a week.

Thanks to advancing technologies and relatively new standards from the U.S. Occupational Safety and Health Administration (OSHA), industry consciousness over silica exposure has grown in recent years. But that’s just the tip of the iceberg as it relates to air quality for construction, demolition and recycling operators, says Jeff Moredock, the executive vice president for Sy-Klone International, an air cleaning equipment manufacturer based in Jacksonville, Florida.

With Moredock serving as the international project lead for the International Standards Organization (ISO), a new standard of in-cab air quality is on the horizon that could help improve both machine and operator well-being and performance.

But even before that standard comes into play, managers can take steps to ensure their operators have optimal air quality while they work.

Problems with air quality

According to Moredock, in-cab air quality is primarily dependent on four different factors: temperature, humidity, carbon dioxide (CO2) concentration levels and dust particle levels.

Temperature and humidity are easily controlled by most HVAC systems. CO2 and dust, however, are not as simple to address.

Some HVAC systems only recirculate the air inside the cab and some, known as fresh air systems, draw air from outside the cab. Either configuration can present significant air quality problems when operating in high dust concentrations, as one recirculates stale air while the other draws dust into the cab.

“There are issues when you talk about recycling facilities or construction environments, particularly when they're not exposed to the atmosphere—in other words, they're inside of a building. When you're running equipment inside of a building and you don't know how much ventilation you're getting, you can have higher concentrations of all of the different types of particles because you're in there moving things around, crushing, abrading, grinding, whatever you're doing, and you're creating all this dust,” Moredock says. “If the ventilation system, the air intakes, then filtration system cannot remove those particles from the air, they will suck them into the cab. The result of that is you increase the concentration levels of these particulates inside the cab, and the air quality goes from good to not good.”

Dust in the cab can be problematic for both the machine and the operator.

When outside particulates get sucked into the cab, they clog the HVAC system and degrade its function.

But even more problematic is the particulates’ effects on operator health. Dust can contain a variety of contaminants, including silica and asbestos, which can be harmful to operators, especially with long-term exposure.

If the HVAC system is not recirculating air, CO2 also starts to build up in the cab. Moredock says CO2 exposure can also create health problems that may be more immediate, especially with the use of diesel-powered machines. More CO2 equals less oxygen in the cab, which can impair cognitive function and decision-making. It also causes the air to feel stifling, which may result in operators opening a window and exposing themselves to even more contaminants.

Regulations currently exist to quantify safe levels of contamination. OSHA’s recent silica regulations lowered the permissible exposure limit (PEL) to 50 micrograms per meter cubed averaged over an 8-hour day. Similarly, ISO 16000 has established that the CO2 concentration for medium indoor air quality is 800 parts per million (ppm).

Moredock, however, says there is a difference between indoor air quality in a typical building and in-cab air quality in a working environment.

“What we found is the 800 ppm was a good mark for buildings, but … you also have ambient CO2, which is what your CO2 level is just walking around outside, and then you have the CO2 level inside the cab with a guy breathing it,” he says. “What we're really concerned about is the difference between those two and making sure that that difference is not substantial.”

Setting standards

The discrepancy in current standards is part of the reason why Moredock is working to create a new framework for assessing air quality.

Moredock is the international project lead for developing ISO 23875, an air quality control systems and air quality performance testing standard for operator enclosures.

“As it relates to standards that directly address air quality, there are very few. In fact, the one that we're writing is the first one that's been written on an international basis that addresses air quality in an operator cab and provides awareness of this as a problem,” Moredock says.

The standard will establish a testing methodology for evaluating the cab’s performance upon manufacturing, as well as methodology for the cab’s ongoing maintenance. Moredock says the standard will be applicable across the entire supply chain, from original equipment manufacturers (OEMs) to industrial hygienists.

“ISO 23875 is unique because of its emphasis on new and retrofit cab air quality system performance. It applies equally to those who design new equipment and those who retrofit used equipment in the field,” Moredock says. “Improving air quality cannot be the sole responsibility of any one group. As the machine passes through its life cycle, it must be continuously maintained and performance tested to validate its proper function.”

Finding solutions

Moredock says he hopes the standard is in place by 2021 at the latest. But until then, there are solutions managers can put in place to maintain good in-cab air quality for their operators.

Keeping the cab well-sealed is an important component. But according to Moredock, keeping fresh air recirculating in the cab is key.

“Fresh air [is important] for two reasons. It dilutes the amount of CO2 that's in the cab by mixing it with ambient air, which has lower levels of CO2, so we're diluting the CO2 in the cab. Then, it performs another function. It puts the cab into a positive pressurization state, which means that we have air coming in through a control source, and then this air must look for a place to get out of the cab,” Moredock explains.

Fresh air, however, can be difficult to come by when in an enclosed working environment.

Moredock says high-efficiency filters can filter air coming into the cab through the HVAC system, controlling the airflow in and out of the cab to minimize CO2 and dust buildup.

Moredock adds that filter pre-cleaners are an important component to help tackle especially dusty environments even before those particles hit the HVAC filter, which prevents clogging. “In the absence of this, you're a victim of whatever dust is outside and how much is there, [and] that relates to how quickly that's going to cause a failure on your air conditioning system,” Moredock says.

The handbook’s recommended HVAC components to maintain high air quality include:

• A pre-cleaner that uses high-efficiency filtration to collect and divert a majority of particles before they reach the filter.
• A high-efficiency filter that captures 95 percent or more of toxic respirable particles from the 0.3 to 10 micrograms per meter cubed range. Moredock says while many favor HEPA filters, MERV 16 filters are cheaper, longer lasting and typically enough to do the job.
• A high-efficiency MERV 16 minimum recirculating air unit to filter fresh air as it cycles through the cabin.
• A cabin pressure monitor that can alert operators if pressure dips below a set level.
• A CO2 monitor with real-time readings.
• Unidirectional airflow to ensure a steady supply of fresh air.

With new standards coming up the pipeline, fleet managers can get ahead of the curve by requesting new machines conform with ISO 23875 from the factory and adjusting old machines to create cleaner air in the interim.

The author is the assistant editor for Construction & Demolition Recycling and can be reached at tcottom@gie.net.