Thursday, June 10, 2010

SingleStream Recycling - Additional Recycled Plastics


The Ann Arbor City Council recently voted to spend over $6.7 million dollars to convert the recycle program from dual stream to single stream recycling. The primary argument made to justify the expense was that additional materials would be collected and that the sale or diversion of these materials from the landfill would pay for the additional cost of the program, including the investment for the conversion.

While the arguments seem logical in a qualitative manner, it was disappointing that the proponents of the transition to single stream recycling did not provide any quantitative data on the amount of additional material that might be collected, the value of this material and the environmental advantage of recycling it.

In both programs paper and cardboard, are collected, this is the fiber stream. Glass, plastics aluminum and steel containers are also collected, the container stream. In dual stream recycling these two streams are separated by the citizens. In single stream recycling all materials are combined at the household source and then later separated by a contractor.

At present, almost all types of paper and cardboard are recyclable. This will not change with the conversion to single stream. However, additional plastics will be allowed in the container component of the single stream program. It is the sale of these materials that must pay the additional $6.7 million cost of conversion to the single stream program if the program is to be cost effective. This report will quantify the additional plastics that will be included in the single stream program.

This report investigates:

How much additional plastic will be recycled in the single stream program?

What is the economic value of this material, or value of diverting it from the landfill?

What is the benefit of recycling this material?



At present only type one and type two plastics can be recycled. Under the proposed single stream program plastics of types 4, 5, 6, and 7 will also be recyclable. But there are additional constraints on the specific items that may be recycled in either program.

First, in the case of most plastic objects the generic type of the plastic is designated by a symbol molded into or marked on the object. The symbol is a triangle of arrows with a number inside the triangle. The number defines the type of the plastic. This labeling system was developed by the Society of the Plastics Industry. It should be noted that the presence of the symbol only designates the type of plastic, not that it is, or is not recyclable. In fact the Society of the Plastics Industry specifically instructs manufactures:(1)

". . . Do not make recycling claims in close proximity to the code" and

". . . Do not use the term "recyclable" in proximity to the code."

A plastic is not recyclable just because the symbol and numbers are molded or printed on the object. The present Ann Arbor recycling program places the following additional constraints on the plastics which may be recycled. (2)

Includes bottle-and-screw-top jar shapes only, marked 1 or 2 (PETE or HDPE), such as milk jugs and bottles used for laundry, cleaners, cooking oil and water. No tubs, such as for margarine or yogurt.  Remove and discard all plastic lids. “

Under the single stream recycling program the following plastics may be recycled: (3)

“As part of the upgrade of the city’s Materials Recovery Facility (MRF) in mid-2010, Ann Arbor will add and recycle all clean plastic bottles and tubs marked #1, #2, #4, #5, #6, and #7. Bulky plastic HDPE #2 items such as buckets, crates, trays, and outdoor furniture will also be accepted.

Please note that the plastics to be accepted must have a bottle (check for a neck) or tub shape (such as a yogurt tub, carryout plastic tray, microwave freezer food tray, berry box, etc.) The plastics meeting the shape criteria must be marked with a recycling number.

No #3 (PVC for PolyVinyl Chloride--used for some shampoo and food bottles), polystyrene foam (aka Styrofoam™), biodegradable plastics (marked PLA or compostable), or plastic bags. “


In order to consider the effect of converting to dual stream recycling we need to consider each type of plastic and the amount that can be recycled at present and in the proposed single stream program. The plastic containers in one household were carefully reviewed. In addition plastic objects in several stores were also reviewed to determine the types of plastics that might be recycled.

The following paragraphs give the symbol for each plastic and the types of additional objects that may be recycled in the single stream program.

TYPE 1 - polyethylene terephthalate (PETE)

Type 1 plastic is currently recyclable if it is a bottle. It should be noted that carbonated beverages sold in type 1 bottles are returnable for a $0.10 deposit in the State of Michigan. PETE is clear, strong and does not break. It is probably the most common plastic used for food and drink containers.

Under the proposed single stream recycling program additional containers that are not bottles will be recyclable. There are two common forms, one is the cylindrical containers commonly used for olives and similar foods selected and filled by the customer in the food store. The other is the rectangular light tubs or clam shell containers used for nuts, fresh and dried fruit, other prepared foods and some produce.

TYPE 2 - high density polyethylene (HDPE)

HDPE is the plastic most often used for milk containers. It is usually translucent, but may be opaque and colored in some instances. Type 2 plastic is currently recyclable if it is a bottle or a screw top food container.

Under the single stream program all type 2 clean plastic bottles and tubs will be recyclable. In addition, bulky plastic HDPE #2 items such as buckets, crates, trays, and outdoor furniture will also be accepted. Type 2 plastic is commonly used for 5 gallon pail packaging of bulk foods. It is not often used in retail size food packaging, only one example, a tofu package was found. Therefore it is unlikely that including container shapes will have a significant effect on the residential recycling of type 2 plastic.

The advantage of recycling bulk HDPE items such as lawn furniture is also questionable since a recent review of plastic lawn furniture in a retail store indicated that all the lawn furniture for sale was made from polypropylene, type 5 plastic, and would not be recyclable under the single stream program.

Another difficulty in recycling bulk items is that the item must be marked with the symbol designating the plastic type. Several bulk items were located were the plastic type symbol was on the package of the product but not on the product. Consequently these would not be recyclable.

TYPE 3 - polyvinyl chloride (PVC or vinyl)

Type 3 plastic, polyvinyl chloride, is not recyclable at present and will not be recyclable in the single stream program. A notable concern of PVC is that it is a chlorinated hydrocarbon and can create toxic fumes if burned.

TYPE 4 - low density polyethylene (LDPE)

Low density polyethylene is not presently recyclable. It will be recyclable in the single stream program if it is in the form of a bottle of food container.

However, this is the material used for films and plastic bags, not bottles and tubs. Since sheet materials are not accepted in the single stream program it is very unlikely any additional type 4 plastic will be recycled in the single stream program.

TYPE 5 - polypropylene (PP)

Type 5 plastic is not currently collected in the dual stream program. It will be collected in the single stream program. Polypropylene is typically a harder plastic that tears or breaks more easily than polyethylene.

While there are some bottles that are made from polypropylene, the most common use is small opaque food containers such as yogurt and soft margarine tubs. These are common, and will probably be the greatest source of any additional plastic recycled in the single stream program

TYPE 6 - polystyrene (PS)

Polystyrene is not presently accepted in the recycle program. It will be included in the single stream program with two important requirements. It must be a tub or bottle shaped container and it cannot be expanded polystyrene (styrofoam). Initially there did not seem to be any type 6 containers meeting the recycling criteria. A few were recently found as packaging for fresh fruit.

Since polystyrene is rarely used in a bottle and most polystyrene tub containers are from the foam version of the plastic very little additional polystyrene will be collected in the single stream program.

TYPE 7 – other, or is made of more than one resin used in combination.

The recycle characteristics of type 7 plastic is very similar to that of type 6. It is not presently accepted; it will be accepted in the single stream approach, but the additional condition that it cannot be PLA, or compostable, eliminates virtually all the type 7 plastic that is likely to be found in the home.

The only common residential use of type 7 is the biodegradable food containers used by some stores such as the Ann Arbor Peoples Food Co-op. It is rather ironic that this store adopted this plastic as more environmentally desirable than the more common type 1 but the City will not recycle or compost it.



Reviewing each of the categories of plastics the only additional materials that will be commonly recycled from residents will be type 1 and type 5 tub shaped food containers. The type 1 tubs are the clear, round containers with separate lids that are commonly used for retail sales of olives, stuffed grape leaves and similar items; and the tray or clam shell containers used for berries, dried fruits, nuts and other produce items. The type five plastic tubs are most often used for dairy products such as yogurt, sour cream, etc.

The amount of these items were carefully monitored in one household over the period of several weeks. The additional containers that will be recyclable were weighed using a postage scale.

In order to test if the monitored household was representative a request was made to an email group asking if members of that group would estimate the additional plastic containers that they would be able to recycle in the single stream program.

Fourteen households responded to the request. The average was consistent with the result from the original household more carefully sampled. The results are in the table below.

As discussed before, the items from the carefully monitored household were weighed on a postal scale. The results were that the cylindrical tubs used for olives and similar food weighed about 1 ounce. Large, 32 ounce, yogurt containers weighed about 1.5 ounce. The small individual serving small yogurt containers weigh about 0.5 ounce and the thin produce tubs also weigh about 0.5 ounce.

For this analysis an average weight of 1 ounce was used for all containers The results by are given in the following table.



The city data indicate there are about 28,000 single or dual family collection points in the city. Commercial and large apartments are not part of the same collection system and are not included on the Recyclebank rewards program. Multiplying the additional weight of plastic each household is estimated to recycle each month by the number of households and by 12, gives an estimated additional plastic collection of 220,000lb/yr

Each month the magazine W4aste and Recycle News publishes some data on the value of recycled materials.(4) The data for published since January 2010 indicates an average value for sorted scrap plastic of about $0.20/lb. This means the value of the additional plastic will be about $44,000/yr.


One of the arguments made to justify the cost of the single stream program is the reduced cost of disposing the additional materials in the landfill.

The present cost to dispose of material in the land fill is $25/ton. (5) The estimated additional recycled material is 220,000 lbs/yr or 110tons. With a disposal cost of $25/ton this is only a cost of $2,750/yr.

In a recent article in the Ann Arbor Observer Mr. McMurtrie stated that single stream recycling could double the amount on materials presently sent to the landfill because of cross contamination (5). He estimated the increase to be 1 to 2 percent of the collected materials. This calculates to between 50 and 100 ton/yr. This additional amount going to the landfill offsets much of the landfill savings from the additional plastic recycling.


When the single stream proposal was brought to City Council, the manager or the solid waste division asserted that the additional costs would be paid back to the city in only a few years. The supporting calculations were not made available to Council or the public. However the Mayor asserted that much of the payback would be from reduced landfill costs

Combining the scrap value of the additional plastics and the reduction in land fill costs provides a total return to the city of approximately $45,000/yr. The cost of implementing the single stream program is over $6.7 million. Therefore the simple straight line pay back period is well over 100 years. Since none of the equipment has anywhere near that life expectancy, the single stream program will never payback.

Since the weight of the additional plastics which are likely to be collected is small it is impossible to believe that a reduction in landfill cost can pay for the program. This is supported by the published industry literature. Waste and Recycling News reported that speakers at the 2010 Chicago Conference on Residential Recycling asserted that greatest myth of recycling was that it was “free”.(6) They asserted that people must expect to pay for recycling. One of the reasons cited was the cost of sorting the recycled materials which is greater in the single stream process.


Some people will find it easier to roll a larger capacity cart to the curb less frequently than carrying the hand totes. This may encourage greater recycling and this is an environmental benefit. However the large cart requires automated pickup and this is not compatible with collection of more diverse hazardous items such as such as used motor oil, batteries, florescent lights, and electronic components. Consequently citizens that wish to properly dispose of motor oil, batteries, and florescent lights must now take them to the drop off station and pay a fee.(7)

Curbside collection is one of the most important aspects of citizen participation in recycling programs. The elimination of curbside collection of used motor oil, batteries, florescent lights will result in more of these hazardous materials simply being discarded. This is detrimental to the environment. Electronic items are now a major problem in landfills. (8) It would be environmentally better to provide curbside pickup of these items to encourage recycling than to collect a small quantity of additional inert plastic.

In addition, the cost of the program, $6.7 million, will require reduction in other solid waste programs programs. One of the programs which may be eliminated is the fall leaf collection progam. This will result in more leaves washed into the storm drains and into the Huron River. This will increase phosphorous content in the river and may result in a degradation of the river water quality.


The single stream program includes automated, mechanical collection. This is an advantage to the company, Recycle Ann Arbor which does the curbside recycling collection.

Combining the container and fiber streams makes sorting much more difficult. Much of the additional cost of the program is for additional sorting equipment, consultants to assist in purchasing the equipment and then in the contractor cost to operate the more complex equipment. The transition to single stream recycling is an advantage to FCR the company contracted to sort and process the materials.

Finally, Ann Arbor has hired a consultant to assist in the transition to single stream recycling. The consultant, Resource Recycling Systems Inc. (RRSI) will also benefit from single stream recycling.


The single stream program will allow some additional plastics to be recycled. A careful investigation of these additional plastics indicate that they represent a very small increase in the total mass of recyclable materials.

The calculation of the value of the additional materials that will be recycled shows that the value of the materials, together with the reduction in landfill costs, is far too low to pay for the increased cost of the single stream program.

The position that recycling is not “free” as presented by the proponents of single stream recycling is supported by the industry literature. This does not mean that recycling is “bad”, only that expansion of any program, such as the one Ann Arbor intends to implement comes at a cost. The question that Council should have asked is whether the benefit is worth the $6.7 million cost.

Part of the cost is that the present collection of hazardous materials such as used motor oil, batteries, and florescent lights is being discontinued so much of this material will simply be discarded instead of being recycled. It would be better for the environment to retain the present curb side collection of the present hazardous materials and increase it to include electronic items than to collect a small amount of additional inert plastic materials.

The implementation is very expensive to the taxpayers, but it is a greater benefit to the contractors in the process than to the taxpayers or the environment.

SENSITIVITY of the Analysis to Parameter Variations

whenever a calculation of this nature is done it is desirable to test the sensitivity of the calculation. In particular is there any parameter that might alter the result? Also is there any reason to believe that the sampled or the estimated values used might be high or low?

From the stand point of the calculation, an error in the value of any of the parameters will only cause a proportional error in the final result.

The sample or citizens interviewed was small and this is a potential source of error in the number of containers recycled. Still there are some good indicators of its accuracy. There is a wide range in the responses, from 0 to 40 containers per month, yet the average value, 10.5, is very close to the value, 10, from the household that was carefully monitored.

The average number of residents in the households surveyed was slightly less, but close to the typical number reported for the Ann Arbor average. There might be some error in the estimated number of container that will be recycled in the single stream program, but there isn't any reason to believe the variation from the number used in the calculation will be significant.

Most of the containers weighed, weighed less than one ounce. One of the households reporting the highest anticipated increase in container recycling stated that the majority of the containers they would be recycling were small containers weighing less than one ounce. The calculation used a value of one ounce for all containers. If there is any variation from this value it is probably that the true value is less than one ounce/container.

The value used in the calculation was an average of all reported values of all recycled plastics. But the source of the data only reported values for the most common and highest priced commodities. The actual recycled stream will include other plastics, like type 7, which have very little if any resale value. The number used for the value of the recycled material is probably high unless the sales value of recycled plastic significantly increases from the value in the first quarter of 2010.

The conclusion is the calculation is not particularly sensitive to changes in any of the parameters. It is also more likely that the estimates used for of the weight and resale value of the additional material are more likely to be optimistic than an under estimate Therefore, it is very unlikely that any of the parameters will change sufficiently to modify the conclusions of the report.


1) Society of the Plastics Industry. SPI Resin Identification Code - Guide to Correct Use


3) A2 Recycling Collection Program to Roll Out July-August 2010

4) Commodity Pricing by Region Waste and Recycling News January through May 2010

5) Tipping Point? , Dave Gershman, Ann Arbor Observer, June 2010

6) No free lunch when it comes to recycling , Jim Johnson Waste and Recycling News. April 12, 2010

7) Recycle Ann Arbor's Drop-Off Station Announces New Fee Structure; December 15, 2009.
Jean Brown,, (734) 662-6288, ext. 115

8) Toxic Chemicals Resulting From The Disposal Of Electronic Equipment
U.S. EPA. Potential Environmentally Relevant Chemicals