On “trash day,” it’s a common sight in most neighborhoods throughout America:  First, a trash truck rolls through to collect the trash at the curb.  Sometime later, a second truck comes through, this time to collect single-stream recycling.  In some places, yet another truck might visit the neighborhood to collect food waste or other compostable organics.  That’s three material types, three trucks, and three routes.  For residents, that means three times the traffic.  For municipal budgets, that means more trucks, more fuel, and more maintenance costs.  There has to be a better way, right?

​

Some municipalities have found a better way, and it’s called co-collection.  Here, we describe what co-collection is, how it works, its benefits, and some potential challenges associated with it.  Overall, co-collection is a practice that has the potential to dramatically change the way we handle trash in America.

​

WHAT IS CO-COLLECTION?

Co-collection is a system in which cities or towns combine multiple collection routes into one, using one truck on any given route.  So, instead of three trucks picking up three different types of material, as described above, a route would have one truck that would pick everything up at the same time, putting it all into one truck.

In a co-collection system of this type, the truck does not use a divided hopper to keep the material types—trash, recycling, organics, etc.—separate.  Instead, all materials are placed in the truck’s single hopper.

However, those materials are not co-mingled.  Co-mingled materials and the so-called “dirty MRFs” that separate them have proven to reduce the value and volume of recyclables and to have limited viability as a waste collection system.

In a co-collection system like the one described here, the materials are separated by the resident into official, municipally-provided, color-coded bags before being placed at the curb or in the trash cart.  For example, garbage might go into a black bag, recyclables into a blue bag, organics into a green bag, and so on.

 

 

WHERE DOES THE MATERIAL GO AFTER IT’S COLLECTED?

After a collection truck fills up with material, it goes to unload at a separation facility.  Sometimes, this is a stand-alone facility.  Other times, it may be on the same grounds as the materials recovery facility (MRF).

When the truck unloads, all the color-coded bags, full of their respective materials, are dumped out.  They are then usually placed onto a conveyor system to begin the separation process.  In the few places in the United States where this is done, the separation process is manual:  Workers pull recycling bags and send them one direction, and trash in another.

 

In many systems in Europe, the separation process is automated.  Optical readers, such as those manufactured by Optibag, “read” the color-coded bags as they pass by on the conveyor.  A series of paddles then “kick” the bags onto the appropriate conveyor based on their color. Optical readers “see” the color of the bags, and use paddles to send them to the right bins.

 

Blue bags go onto the recycling conveyor, black bags onto the trash conveyor, green bags onto the organics conveyor, and so on.

At the end of each conveyor line, workers load up the materials for further processing or for disposal.  For example, the trash gets sent to the landfill or waste-to-energy incinerator, the recyclables are sent to the MRF for further processing, and the organics are sent to a composting facility.

​

 

WHAT ARE THE BENEFITS OF CO-COLLECTION?

 

Co-collection has the potential to offer several benefits to a community.  Here’s a quick summary.

​

For Municipal Governments

Co-collection can help a city reduce its equipment, maintenance, a fuel costs.  Combining two routes into one will not cut costs in half, as trucks will fill up more rapidly and need leave their routes more often for unloading.  However, some cities have estimated that combining two routes into one reduces costs by about 20%.  That’s a substantial savings.

In addition, it sets up a system in which a community can offer services to help its residents get to “zero waste,” or at least very close to it.  It allows a wide range of opportunities for source-separating a range of materials that are normally difficult to recycle.  For example, glass is a real problem for many MRFs.  It tends to break under compaction in single-stream recycling, contaminating paper and other fibrous material.  In a co-collection system, cities can specify that residents use a special color-coded bag for all glass, thereby keeping it out of the other recyclables and solving the problem.  Other opportunities may exist for separating and recycling plastics that are often thrown away, such as plastic utensils, plastic wrap, etc.

Ultimately, it’s about keeping collection costs low and minimizing the amount of material that gets sent to a landfill or incinerator.  Co-collection can help a city or town do both.

​

For Residents

For residents, co-collection means less truck traffic in their neighborhoods on trash day.  It also means that they could have the opportunity to recycle nearly every piece of waste material they generate in their homes.

​

For Haulers and Disposal Facilities

Haulers and disposal facilities that support co-collection can build a real competitive advantage, differentiating themselves from other competing alternatives in the area.  For example, a MRF that builds a separation facility on its grounds would now be able to offer a unique capability for the municipalities in the area, thereby increasing the tonnage it can attract.  For a MRF or a disposal facility, tonnage is revenue.

​

WILL CO-COLLECTION WORK ANYWHERE?

While co-collection can be made to work anywhere, there are some things that an area will need for co-collection to be viable.  First, co-collection requires a separation facility.  This can be a stand-alone facility, owned privately or by a government / quasi-governmental entity.  Alternatively, it can be attached to an existing MRF or disposal facility.  Often, the requirements for such a facility are relatively straightforward and simple, even the ones that use optical sort technology.

Another requirement is bag-breaking technology for recyclables.   The MRF that accepts the bagged recyclables will need to have the ability to de-bag them before further separation and processing.  Not all MRFs have de-baggers, but may want to consider investing in one if they believe the ability to support co-collection could offer a competitive advantage in their area.

Finally, a municipality must make the decision that it wants to use co-collection.  When it does this, it will need to put in place a uniform bag program, in which residents are required to used specific, official, color-coded bags for the various material types.  In such a system, cities can either sell the bags to residents or provide them free.  In most systems, the trash bags are the most expensive, sold through local grocery stores or other retailers.  The other types of bags are either provided for free or at subsidized prices, also made available through local stores.  The goal is to provide an economic incentive for residents to separate materials and generate as little trash as possible.  Towns that already have bag-based pay-as-you-throw (PAYT) systems are best positioned to use co-collection, because their residents are already accustomed to using official municipal bags for waste.

 

WHERE IS CO-COLLECTION USED?

Co-collection is not in widespread usage in the United States.  North Augusta, SC uses a version of co-collection, as does St. Peters, MO.  Some individual haulers have implemented the system, such as Michiana Recycling and Disposal, which uses it with multiple municipalities in MI.

​

In Europe, co-collection is more common.  In Sweden, Stockholm offers it for multi-family properties.  Facilities in Linkoping and Eskiltuna provide processing of co-collected materials for multiple municipalities.  Oslo, Norway also uses the approach.  All told, 36 municipalities in Sweden and 58 in Norway use co-collection systems.  France has also gotten in on the act, with a facility in Forbach.

​

THE FUTURE?

While co-collection will not be the norm in the United States overnight, it is a system that shows considerable promise.  Its ability to reduce costs while helping cities get closer to “zero waste” makes it an attractive approach.  Cities and towns, haulers, MRFs, and disposal facilities should be investigating this approach in detail, as it could offer significant benefits.