Single Stream Recycling

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Long time readers may be aware that my father, Ron Danner, is an emeritus professor of Chemical Engineering at Penn State University. This is the second of two columns that we are co-authoring, both of which are pertinent to issues right here in the Southern Part of Heaven. Last week we addressed the choice between paper and plastic bags. This week we provide a review of single-stream recycling.

Aside from being environmentally conscious, municipalities have financial incentives to implement recycling programs. Glass, paper and plastic that residents throw in the garbage must be landfilled. If they are recycled, they can be sold. The three most common approaches to recycling are listed below.

  • Single-stream: Put all recyclables into one bin.
  • Dual-stream: Put paper products in one bin and all other recyclables in another.
  • Source-separated: Divide recycling into many different bins based on material type such as paper, aluminum, clear glass, and brown glass.

In order to select from among these options, a municipality needs to consider all of the steps in the recycling process.

  • The first step involves considering what behaviors can be expected from residents. As you require more separation at the home level, you need more recycling-focused residents. As the amount of separation required is reduced, residents tend to increase the amount of material that they recycle, which in turn reduces the amount that goes to the landfill.
  • The next step involves the collection of materials. The trucks that collect recycled materials must have the same number of compartments as the number of distinct bins at the residence. Multi-compartment trucks are more expensive than the single compartment trucks that can be used in a single-stream recycling approach.
  • The third step is the separation of the materials at the recycling facility but automated machinery. The goal of the recycling facility is to separate everything back out into distinct categories. This task is obviously easier to accomplish if the resident performs more separation.
  • The final step is the disposition of the separated materials. Here, economics plays an important role. The amount paid for a ton of recycled material depends upon the quality of the product. The higher the level of contamination – paper mixed in with glass, or type 1 plastic mixed in with type 2 plastic – the lower the price.

A single-stream recycling facility is essentially a series of conveyor belts. Here is a typical setup.

single stream recycling pic 1

Materials from the trucks are dumped on to the first belt and workers extract the materials that are not acceptable, such as batteries or fluorescent light bulbs, by hand. This belt leads to a separator system that drops out the heavier materials such as cans and bottles and leaves the paper, cardboard, boxes, and the like. Each of these streams are directed to further conveyer belts which separate materials using puffs of air to knock off lighter materials such as plastic bottles and magnets to separate metals. Optical sorting technologies are used to identify different plastics and separate them again using puffs of air. The sorting equipment looks like this.  Two of the biggest problems in the overall process are plastic bags, which tend to wrap around the equipment, and glass, which tends to break and contaminate the final products. Therefore, if you ask residents to perform more sorting at home, the products from your recycling plant will be more uniform and fetch a higher price. Unfortunately, if you take this route, residents will recycle less material reducing the volume of material that you can sell and consequently filling up your landfill faster.

Orange County, North Carolina switched from dual to single stream recycling in 2014. In the first year of the program, the volume of recycled material grew by an impressive 16%. This improvement is part of a long-term trend. In 1991-1992, Orange County landfilled 1.36 tons of waste per person per year. This value has now dropped to 0.49 tons, a decrease of 64%. While this is an impressive improvement, we still landfill approximately twice the amount of the average person in the European Union.

In order for Orange County to catch up with the French, the Danes, and the Czechs, we need to maximize the amount of material we recycle while not putting inappropriate material in the bin. Follow this link to the list from Orange County Solid Waste for an explanation of what can and cannot be recycled. Post the recycle guidelines near your recycle bin and check before you throw!

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Paper or Plastic?

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Long time readers may be aware that my father, Ron Danner, is an emeritus professor of Chemical Engineering at Penn State University. I am pleased to announce that for the next two weeks he and I are co-authoring two Common Science columns, both of which are pertinent to issues right here in the Southern Part of Heaven. This week we address the choice between paper and plastic bags and next week move on to an analysis of single-stream recycling.

Recently at a meeting of scientists and engineers the speaker asked, “Which choice should you make when the checkout clerk at the grocery store asks, ‘Paper or plastic?’” The vast majority answered paper. Most people, several states and some retail chains are also making this same choice. California bans single-use plastic bags at large retail stores. North Carolina instituted a ban on plastic bags for the Outer Banks region in 2009, but rescinded it in 2011 due to tornado damage that affected a major distributor of paper bags. Delaware requires stores to provide facilities for returning plastic bags for recycling. Whole Foods Markets no longer offer plastic shopping bags at their stores. Plastic bags have clearly fallen out of favor, but are paper bags really the “better” choice?

Let us look at the scientific basis upon which one might best make the paper versus plastic choice. The following data are from Nashville Wraps, Hendersonville, TN, a maker of both plastic and paper bags.

Comparison based on 1000 grocery shopping bags

Characteristic Paper Plastic
Weight (lbs) 140 15
Cost $230 $35
Shipping cost $28 $3
Diesel used in transit (gal) 0.58 0.06
Biodegradable? Yes Possibly*
Recyclable? Yes Yes
Air emissions (lbs of CO2 equivalent)** 101 62
Petroleum used (lbs) 3.67 1.62
Indefinite recycled life? No Yes
Water use in production (gal) 1000 39

* If the appropriate oxo-biodegradable plastic additive technology is used.

** Air emissions include everything from making the electricity consumed in the process, to making the product, to shipping the product, to disposing of any wastes.

The statistics suggest that plastic is preferable in every category, with the possible exception of biodegradability. To fully understand this, one needs to look at it in terms of a life cycle analysis – that is, the total life history from raw material acquisition, to manufacturing, to reuse and maintenance, and finally to recycle/waste management.

Paper is made from trees – a renewable resource – which is good. But, as you can see from the diesel, petroleum, and water data, the making and shipping of paper bags consumes a lot of resources. Consider the clear cutting of the forest, the trucks used to haul away the heavy lumber, the large machinery used to strip the bark and chip the wood, the high-temperature, high-pressure conversion of chipped wood to pulp, the washing and bleaching of the pulp, and then finally the dilution of the pulp with water so that it can be spread on conveyors to form paper. Further, since paper bags weigh more and take up more volume than plastic, it requires more fuel to ship them.

Plastic is made from petroleum oil – a non-renewable resource – which is bad. However, even after accounting for the refining of the oil, the production process used to make plastic bags consumes significantly less energy and water compared to paper production.  Due to this less energy-intense process, plastic outcompetes paper when considering total emissions of carbon dioxide.  Clearly, plastic is the winner when considering energy and water consumption and impact on global warming.

Both paper and plastic bags can be recycled, but determining whether one material has an advantage over the other in this arena is a complex question. Making recycled paper requires re-pulping the old bags, which requires the same energy and water consumption associated with making paper from trees. In contrast, it takes only about two-thirds the energy to make recycled plastic compared to the virgin plastic. Many curbside recycling programs do not accept plastic bags, as they tend to cause problems with the recycling machinery. Most grocery stores, however, provide receptacles to recycle plastic bags. Because the recycling process causes some damage to the polymer chains that make up the plastic, you can’t make grocery bags from recycled plastic. However, recycled plastic from bags can be made into such things as plastic lumber for outdoor uses, for example deck planking and boat docks which in turn saves trees. So, although the comparison on the recycling front is a bit of a mixed bag (don’t miss the pun), plastic still comes out on top.

Some paper and plastic bags end up in landfills, where clearly paper will degrade much more quickly than plastic, right? This turns out not to be true. Without aeration and water, decomposition of materials, paper included, is very slow and can take years. Landfills are lined to prevent water entering and then leaching out contaminants into the nearby environment. The materials in the landfill also tend to settle into a monolithic heap that prevents air from infiltrating. Due to these factors, plus the their bulky nature, paper products are the single biggest users of landfill space. So if a bag has to go to the landfill, it should probably be plastic by virtue of size.

What about composting? All paper and a few plastics can be composted. Conditions in a typical composting operation include both water and air flow, and thus are favorable to microbes that break down the paper.  Plastics made from corn are also readily compostable, even more so than paper. However, since corn is a food source and is an expensive raw material compared to oil, there is not much biodegradable plastic around. So on the composting front, the scales tip towards paper. If you have a compost bin at your house, you can readily compost paper towels – use the kind without any patterns – and shredded paper.

Reuse of bags is also an important consideration. The paper-versus-plastic choice on this front seems to be more of a toss up. Paper bags generally hold considerably more than plastic bags, but the plastic bags are reused more often. Let’s call this one a tie.

After reviewing these data, it seems clear that plastic is the better overall choice. The problem comes when the bags are not disposed of properly. Discarded plastic bags blow around easily, are an aesthetic blot, and have proven to be a significant marine risk to turtles who apparently mistake them for jelly fish. The risk to marine life is what motived the ban on the use of plastic bags in the Outer Banks of North Carolina.

If you want to be a good eco-citizen, your choices for taking your groceries home should be in the following order:

  1. Shun both paper and plastic! Use reusable canvas bags over and over again.
  2. Use plastic bags and reuse or recycle them back to the store.
  3. Use paper bags and reuse or send them to composting.

Happy shopping.

Have a comment or question? Use the interface below or send me an email to Think that this column includes important points that others should consider? Share this column on Facebook or Twitter. Want more Common Science? Follow me on Twitter on @Commonscience.

Orange County Governments Talk Recycling Funding

County and town elected officials met Thursday night to work out how to fund recycling and solid waste services.

Legislative boards from the towns of Chapel Hill, Carrboro and Hillsborough met with the Orange County Board of Commissioners.

The Solid Waste Advisory Group (SWAG), made up of elected officials from each local government, has come up with two funding options.

  • Option 1: A two-part fee with $94 a year for urban property and $118 per year for rural property.
  • Option 2: A flat fee of $103 per year for all Orange County property. (The exact dollar amounts could change since projections are based on the fiscal year 2014/15 budget.)

Board members from the county and towns said they would prefer a flat fee, but not members of the Chapel Hill Town Council.

“Right now I am unwilling to ask people I represent to pay more to achieve a one-fee system,” said Chapel Hill Town Council member Jim Ward. “Chapel Hill taxpayers are paying for more than they are getting in services.”

Chapel Hill Mayor Mark Kleinschmidt pointed to a UNC survey that found town residents make up only 11 percent of those who use the county’s solid waste convenience centers. He said the two-part fee would be more equitable than the flat fee.

Others said the flat fee would be a way to bring together all Orange County residents and spread out the costs.

“You all know I teach,” said Carrboro Alderwoman Randee Haven-O’Donnell. “My students, after their lunch they’ve got paper; they’ve got bottles sitting on their tables. And if the mindset was, ‘I’m only going to take care of my own recycling, and we didn’t help with the other recycling’ . . . where would we be?”

O’Donnell drew a comparison between students helping out with the whole group’s recycling and a flat fee for the whole county.

County Commissioner Barry Jacobs, the chair of SWAG, also favors the flat fee.

“I think we spend way too much time trying to figure out who’s getting over on whom instead of saying we’re all in this together,” said Jacobs. “We have a bigger opponent in Raleigh that’s going to bring things down on us that’s not going to be good for any of our governments . . . We’re going to have various challenges that we can only even begin to address if we feel like we’re partners.”

The governments pondered the possibility of piloting a funding option for one to three years. Officials could gather data on how well it’s working and then reassess.

The four governments could agree on a funding plan for recycling and waste services by the end of April.

Town and County Leaders Debate How to Pay for Recycling

Town and county leaders are coming closer to consensus on how to fund recycling pick-up.

Leaders from Hillsborough, Carrboro and Orange County agree all residents should pay a flat fee to fund recycling pick-up.

Solid Waste Director Gayle Wilson says the $103 fee would apply to all developed properties throughout the county.

“This option presents, sort of, a new funding paradigm and a new way of viewing the solid waste program,” he says, “in that it eliminates any obvious division between rural and urban boundaries.

“And [it] reflects how our program is actually administered and operated, which is a fully integrated program. No more multi-tiered patchwork of fees.”

Town and county officials have agreed to collaborate on recycling. To do that, they will need to sign off on a funding plan by the end of April so the new fees can be incorporated into next year’s budget.

A Solid Waste Advisory Group made up of elected officials has been working for six months to bring two options to the table. One is a tiered option that charges urban households $94 and rural households $118. The other is a flat fee charged to all residents.

Both options would require the $1.85 million annually the county has already been allocating from its General Fund.

Chapel Hill Mayor Mark Kleinschmidt says if all households pay the same fee, residents of Chapel Hill will carry a heavier weight than other residents.

“35 percent of the fees that would be collected from the recycling fee, would be allocated to join that $1.8 million dollars to pay for all of the solid waste convenience centers,” he says. The convenience centers are all located in more rural areas of the county.

Kleinschmidt adds, “As a municipal resident, when I look at that I say, ‘Ok 35 percent of what I pay in recycling is going to go toward convenience centers.’ And, if you live in Chapel Hill, one half of that $1.8 million is coming from you and your neighbors.”

He did say that he believes there will, ultimately, be an agreement between all involved parties.

Regardless of which option the boards and council choose, the program would extend recycling pick-up to all homes in Orange County. Wilson told Commissioner Renee Price this can be done, despite challenges including long gravel driveways and small private roads.

Currently 700 low-income homeowners have their solid waste fees subsidized by the county. With the expansion of the recycling program to more rural areas, Board Chair Earl McKee says that number could go up.

“I expect that as you get out into the more rural areas, you will have more elderly who are [on a] very limited income and more who are financially stressed,” he says.

Commissioners on Tuesday agreed they favor the flat rate, but left room to negotiate with Chapel Hill.

All parties will discuss the plan at next week’s Assembly of Governments.

New Recycling Carts Roll Out for OC Residents

The delivery of 7,000 blue recycling carts to residents of Orange County is underway.

Delivery began last Friday and officials are hoping to have the drop offs completed by the end of next week, barring any weather complications.

Blair Pollock is a Planner with Orange County Solid Waste, and he says there were too many variables for the county to determine who received a cart. To simplify the process, they distributed new 95-gallon capacity carts at the request of residents.

Pollock says he did not have the exact distribution locations, but many clusters of homes likely all signed up for carts – specifically homes just outside the town limits.

“They look just like an in-town [neighborhood], but they happen to be just out of town. The odds are good that the vast majority of those are going to switch,” he says. “And the odds are further good that, if 80 percent switched and the other 20 percent didn’t, there may be some that come back. We’re already starting to see a little bit of that.”

Pollock says they had 7,000 requests for new carts among the 14,200 residents who were eligible to receive them. He adds they have a small surplus for those late to decide they would like to have a recycling cart.

“We ordered about 500 more carts than we had orders for,” he says. “We’re hopeful we’ll be able to fill most of the request for people now.

“Otherwise, between the possible expansion of the routes [depending upon the budget] and if there’s a bigger second request for carts, we’ll try to order some more next fiscal year.”

Pollock says the new carts, which have a capacity of more than five of the recycling bins county residents are currently using, will increase efficiency of recycling in the area. He adds the infrastructure is in place to handle the additional waste.

“The markets are reasonably good for all of these materials,” he says. “North Carolina, in particular, has a very robust plastic recycling industry.”

Residents can begin using their recycling carts immediately upon receiving them, and the pickup service will operate on a bi-weekly schedule. Pollock says if the lid of your cart does not fit properly upon arrival, it should conform back to the correct shape in less than 48 hours.

Residents can choose to keep their bins to use as intermediate, or overflow, storage. They may also return their bins to the convenience centers where they currently deposit their recycling.

And there will be no change for residents who chose to continue recycling with their bins and manually dropping off at the convenience centers.

Blue Recycling Roll Carts Set To Roll Out In Orange County

The Orange County Board of Commissioners last week approved the purchase of 7,600 recycling roll carts at a cost of $444,144. Chapel Hill and Carrboro received 90 gallon carts to replace the smaller bins earlier this year.

“I’m very supportive of this and I think that the people in the county, the 7,000 people that want their roll-out carts are going to be thrilled,” said Commissioner Penny Rich.

The county’s rural recycling program serves only a fraction of the residents of unincorporated Orange, about 13,700 households. Others take their trash and recycling to one of the five solid waste convenience centers around the county.

When commissioners first debated purchasing the roll carts for county residents, some residents objected, saying their long driveways and lack of curbs made the carts hard to use.

Gayle Wilson, director of Orange County Solid Waste, told the board slightly more than half of the current customers requested roll carts. He asked the board to authorize the purchase of additional carts in case others changed their minds.

“It is expected that once we start distributing the carts, people will decide that they do want a cart rather than continue to use their bins, or they may have not responded previously and saw a nice, shiny new bin at their neighbors and they call up and they want one,” said Wilson.

Commissioners approved it by a 6-1 vote with Chair Earl McKee opposing. While the purchase had broad support on the board, some, including Commissioner Barry Jacobs, worried it might be short-sighted, coming at time when the towns and county are working on a long-term plan for solid waste.

“Considering that the Solid Waste Advisory Group is looking at the methods for funding curbside or roadside pickup, is this not putting the carts before the horse?”

Jacobs serves on the Solid Waste Advisory Group (SWAG), an intergovernmental work group tasked with identifying a county-wide solution to handle trash and recycling as well as a means to fund it. He and fellow SWAG member Rich told board members the work group will present a slate of proposals for funding recycling pick-up in the spring of 2015.

In the meantime, the new blue carts will roll out in January to 7,000 Orange county residents.

Local Governments Hashing Out Agreement for Next Year’s Recycling

A Solid Waste Advisory Group representing Orange, Chapel Hill, Carrboro, Hillsborough and UNC is working on a plan to fund curbside recycling for all concerned next year.

SWAG, as it’s called, needs to come up with a recommendation by March, because the current funding source dries up in June.

“We’ve been working on a new interlocal agreement, and we’ve gone through several iterarations,” said Carrboro Mayor Lydia Lavelle at Wednesday night’s Assembly of Governments meeting.

She and fellow Solid Waste Advisory Group member Mayor Mark Kleinschmidt of Chapel Hill asked members of the four governing bodies of Orange, Chapel Hill, Carrboro and Hillsborough for more time to come up with a new interlocal funding recommendation for curbside recycling.

Kleinschmidt, Lavelle and others from SWAG had hoped to come into last week’s meeting with that recommendation, but talks are still ongoing. SWAG now hopes to have a recommendation by spring of next year.

That request for more time was granted unanimously.

SWAG has met four times between late August and early October since it was appointed with two members of each local governing body.

During that process, representatives from UNC and UNC Hospital were also invited to join in.

Back in June, Orange Commissioners voted to spend $2 million from the solid waste reserve fund to pay for rural and urban recycling pick-up for the next fiscal year.

But that mechanism comes to a halt on June 30, 2015.

Kleinschmidt told WCHL last week that he’s hopeful that a new agreement is near. He suggested there’s a spirit of cooperation engendered by the county’s actions in June.

“The county took a big risk,” said Kleinschmidt, “and I was really proud of them – with the leadership that’s on the Board of Commissioners right now. They went forward last year and got everybody those blue recycling carts, so that we could continue with curbside recycling.

“They dipped into their own solid waste funds to make sure that we could have curbside recycling in Chapel Hill and Carrboro for this year. And they had no promise that we were going to have an agreement on how we could move forward after this year is over.”

Lavelle told WHCL last week that she agrees with Kleinschmidt that progress is being made.

“I think we all are making good-faith efforts towards a new agreement,” said Carrboro Mayor Lydia Lavelle. “I think that’s our objective. I think we’ve asked a lot of questions about, what are all the fiscal assumptions that kid of underlie the enterprise fund, and what’s the supporting data, if you will, for what the fees would be? So, we’re kind of working through that, and understanding that better.”

There’s definitely an incentive to get an agreement done. Since Orange County rolled out 18,000 blue recycling carts this past summer, curbside recycling has gone up 29 percent.

Blue Recycling Carts Heading To Rural OC Soon

Additional reporting by Aaron Keck

Almost all the new rolling recycling carts are in use in the municipal sections of Orange County, and rural households should be following closely.

“The commissioners did authorize the purchase of 7,000 carts for the rural area,” says Blair Pollock, a Solid Waste Planner with Orange County Solid Waste Management. “

He says there are roughly 13,700 households on the recycling route in the rural part of the county.

However, he says the big gap between the two numbers may not be a bad thing.

“A: we know that not a lot of people recycle at the curb,” Pollock says. “We know that a lot of people will bring their recyclables to convenience centers. And B: not everyone’s going to want a cart. If you have a long driveway, maybe you’d rather keep your bins. In the rural area, there’s a lot more impediments to everyone using a cart.”

He says, in order to find out how many carts are needed, a survey is being conducted in the next several weeks to ask who wants to opt in to the program.

Once the numbers are tallied, the carts will be ordered and delivered.

“We’ll get the carts ordered by November, and we’ll be able to distribute them next January and start collection around February,” Pollock says.

Pollock says that is a carefully-calculated but soft timeframe but that there are always problems that could arise.

“Can you says, ‘ice storm’,” Pollock says.

Let’s hope not.

OC Curbside Recycling: Some Tips For First-Time Cart Users

Orange County has delivered more than 18,000 new blue recycling carts to single-family households in Carrboro, Chapel Hill and Hillsborough, and Orange County residents seem to be adjusting well to the new system.

But there are still a few minor kinks that can be easily worked out.

“Orange County Solid Waste has completed the distribution of over 18,000 carts in Carrboro, Chapel Hill and Hillsborough for single-family recycling,” said Orange County Solid Waste Planner Blair Pollock. “They’re now all in use. We’re completing the third week of collection with the carts. And by and large, people seem to be happy. But there’s still a few glitches in the system,” said Orange County Solid Waste Planner Blair Pollock.

There are a few things that folks who are new to curbside recycling should know.

Carts should be placed with the cart lid facing the street. That will ensure that the lid opens right into the truck when the robot arm lifts the cart off the ground.

Pollock added that the cart wheels should be flush against the curb, and that carts need to be at least three feet away from possible obstructions, such as telephone poles, fire hydrants, and trees.

Pollock said that even though some people have yet to catch on to all the steps of modern recycling, workers are managing to make all of their pickups, while striving for more efficiency.

“We’re trying to encourage all those things so that more of the collection can be automated, and therefore, done more quickly and more efficiently,” said Pollock. “It keeps the cost down, and frankly, it also reduces worker injury.”

The newer automated system is a welcome change for workers making the pickups. In the old days, one person drove the truck, while another got out as many as 500 times per shift, to lift between one and three heavy bins at each stop.

Pollock said that if Orange County residents can remember to adhere to all of the recycling steps he mentioned, they’ll be helping some grateful public employees avoid unnecessary manual labor.

He added that if you have any questions about curbside recycling, you can call the Orange County Solid Waste Department at 919-968-2788; or send an email to

Carrboro Aldermen to Vote on $75K Grant for Recycling Carts

The Carrboro Board of Aldermen will vote Tuesday on whether to accept a $75,000 grant for curbside recycling carts.

Stemming from an inter-local agreement between Orange County and The Towns of Hillsborough, Chapel Hill and Carrboro that was approved by all parties in February, nearly $168,000 from Orange County would be added to Carrboro’s $75,000 grant from the North Carolina Department of Environment and Natural Resources, for a total of nearly $243,000.

That money would go toward ensuring that every household in Carrboro is equipped with a curbside recycling roll cart.

Under the inter-local agreement, the Town is required to pay Orange County an amount equal to any grant it receives for the project.

That’s just one of the items on a busy agenda for Tuesday night’s Aldermen meeting, which takes place at 7:30 at Town Hall, located at 301 West Main Street in Carrboro.