Last November, a California communi-ty boldly did what few have done —

or even imagined possible: They began torecycle their diapers. Just to be clear, thismeans dirty diapers, disposable bed liners andfeminine hygiene products, technically knownas absorbent hygiene products (AHPs).

Billions of diapers Only 2 percent of parents living in the U.S.are using reusable cotton diapers for theirbabies. Everyone else takes the more “con-venient” route with the one-way, disposablediaper. In fact, the U.S. Environmental Pro-tection Agency (Washington) estimates thatthe country generates annually about 18 bil-lion disposal diapers. That’s about one tonof disposable diapers per baby before toilettraining.

EPA research also suggests that the aver-age diaper takes about 500 years to decom-pose. American landfills are composed of

time, tip fees (gate fees) were competitivewith the cost of local landfills, at about $150($Cn) per metric ton. But it didn’t take longfor Ontario’s waste to start flowing south tocheaper disposal options in the U.S. A fewyears later, Knowaste LLC shut its Ontariofacility because it could not compete againstthe disposal alternatives.

Throughout most of the 1990s, KnowasteLLC, now based in New York City, refinedthe recycling technology and began lookingfor opportunities in Europe and Asia wheredisposal costs were more cost competitive.

Recycling AHPs todayIn 1999, Knowaste opened a large-scalestate-of-the-art facility in Arnham, Holland.The facility can processes up to 100,000tons of used AHPs per year collected from

about 1.5 to 4 percent by weight of AHPs.This amount is also on the rise, as the largebaby boom generation gets older and con-sumption of adult incontinence productsincreases. Given these facts, it’s not surpris-ing that AHP recycling is gaining interest.

In the beginningAbout 14 years ago, a mother from Ontariobegan to research possible solutions for thisgrowing waste problem. After several yearsof raising money for research and develop-ment (and good timing, considering recentmandatory provincewide hikes in landfill tipfees designed to stimulate recycling),Knowaste LLC was born.

The company’s first pilot facility openedin Mississauga, Ontario and then processedabout 4,000 to 5,000 tons of AHPs. At the

Clarissa Morawski is principal of CM Consulting (Toronto). She may be reached at (416) 682-8984 ormorawski@interlog.com.

Resource Recycling March 2003 1

THEPOOPONDIAPERRECYCLING

One small town’s groundbreaking program maylead the way for recovering valuable materialsfrom an unlikely waste.

by Clarissa Morawski

Reprinted from

RESOURCERECYCLINGNorth America’s Recycling and Composting Journal

remaining materials are directed into the con-tinuous part of the process for fine screeningand cleaning to produce a quality pulp. Thepulp then is thickened and sold.

The water is clarified in a dissolved airflotation (DAF) tank and recycled in the facil-ity as dilution. Waste diverted from the screenand cleaner, along with the sludge extractedby the DAF, is sent to the municipal sewagesystem (a requirement of the plant’s permit).All discharged water is treated internally toreduce suspended solids.

CostsThe cost of a KDP machine is $750,000 witha two-year warranty. Although operationalcosts will vary depending on factors such asenergy, labor and water costs, Knowaste esti-mates direct operating costs including main-tenance will run at about $60 per ton (notincluding material revenues). If a KDPmachine is set up within a MRF, then baggedmaterial can be collected curbside or via drop-off sites and sorted with other recyclables,incurring only incremental collection costs.Depending on the costs of alternatives, dia-per recycling can prove to be not only envi-

trommels where residual fibers and waste areremoved by washing. Plastics are pressedand pelletized for sale to the market.

The pulp stream goes through a series ofcoarse screens to further remove plastics. Thepulp stream is treated to deactivate the superabsorbent polymer (SAP), which makes itpossible to separate out the fiber.

The deactivated SAP, along with residualsmall plastics, is separated from the fiberthrough a cleaning process. The deactivatedSAP can be collected and reactivated forreuse. Currently, however, deactivated SAPis not being reused because AHPs from thecommercial sector contain much less SAPthan diapers, resulting in poor economies ofscale to develop a SAP market in Holland.

Fibers then are put through a fine mechan-ical washing, cleaning and screening process.The high-quality clean fiber is pressed, baledand sold to the market.

The water extracted in the washing andthickening steps is sent to internal treatmentusing a dissolved air clarifier and then recy-cled in the system as dilution water. In Arn-ham, sludge from the clarifier, as well as thefine screening and cleaning rejects, are thick-ened and sent for composting.

In the KDP version, the technology incor-porates a batch processor and a continuousfiber processing system. The batch process-ing in the first stage combines the functionsof shredding, pulping, SAP deactivation, san-itization and separation in one step.

The process begins with loading the dia-pers into the batch processor, along with thechemicals (chlorine and aluminum sulfate )for sanitization and SAP deactivation. As theprocessor turns, it shreds the diapers andexposes the contents to the chemicals. Sim-ilar to a washing machine, water is continu-ously pumped into and extracted from theunit, a process that continuously removes thefiber, deactivated SAP and waste.

At the end of the cycle, the washed plas-tic is extracted and pelletized, while the

Resource Recycling March 20032

Percent Material by weight Processed into End useMoisture 55 sanitized and clarified re-circulated in the

waste water recycling processFiber 24 high-quality fiber, pressed paper products and packaging,

and packaged for shipping construction materialsPlastic 10 pelletized plastic artificial wood and

plastic products Sludge 6 collected and chemically used in compost in Holland;

treated material discharged to municipal sewer system in California

Super absorbent deactivated absorbent can be reactivated for agriculturalpolymer 5 polymer applications to help soils retain water

Source: Knowaste LLC, 2003.

Table 1 Absorbent hygiene product recycling loop

Shifting the costThe average diaper costs between 20 and30 cents each. At about 5,500 diapers perton, the cost to recycle diapers (not includ-ing capital or collection costs) would beabout a penny per diaper. By applying astandard model to a diaper recycling pro-gram, one can estimate that an extendedproducer responsibility (EPR) programcould result in a consumer cost increase of3 to 5 percent per unit. In light of thisexpense, the diaper industry instead hasbeen promoting taxpayer-funded, munici-pal composting as the diversion solution forone-way diapers.

Western European old-age facilities, day-care centers and other commercial estab-lishments.

Last November, a small-scale version ofthe technology called Knowaste DiaperProcessor (KDP) began recycling used dia-pers from 220 households involved in a six-month test pilot in Santa Clarita, California.If successful, the program will expand tothe entire community of 143,000 house-holds.

Today, Santa Clarita is collecting aboutone ton of AHPs a week. The material isplaced by residents in plastic bags and storedin 64-gallon bins usually placed outside ofthe home or in the garage (bags and bins wereprovided by the city). Although haulers andprocessors elsewhere have expressed concernabout handling AHPs, Santa Clarita city staffreport that their program is very popular withresidents and collection is going smoothly.

With a throughput of only one ton perweek, however, poor economies of scalemake it difficult to market output material.Knowaste LLC plans to use the secondaryfiber to produce paper-based flowerpots forthe 220 residents involved in the pilot.Knowaste estimates that a throughput of 10tons a week would make secondary mate-rial marketing viable. Once the pilot iscompleted in May, the city council will beprovided with a cost-benefit analysis todetermine whether to expand the programor to continue the pilot for another sixmonths.

This small-scale KDP seems to be gain-ing ground in smaller community diversionprograms. With a footprint of 1,500 squarefeet and 18-foot height clearance, the KDPcan be placed directly in a municipal materi-als recovery facility (MRF). The unit has amaximum capacity of 5,000 tons (based onthree shifts) of AHP per year (one ton perhour), and can result in up to 1,000 to 1,200tons of pulp and 500 to 600 tons of plasticoutput for end-use markets.

The technology The Knowaste recycling process separatesthe components of AHPs into:� 55 percent moisture � 24 percent paper fiber� 10 percent plastic (60 percent low

density polyethylene and 40 percentpolypropylene)

� 6 percent sludge � 5 percent super absorbent polymer

(which provides the water retentionfunction).Bagged material is loaded onto a convey-

er belt and shredded into small pieces. Thematerial then is sent to a pulper, which sani-tizes the material and initiates the process ofseparating the components to expose themfor chemical treatment. The plastic isremoved by finger conveyors and is sent to

Resource Recycling March 2003 3

ronmentally preferable to disposal, but eco-nomically viable as well, say company officials.

A statewide system?The development and implementation of dia-per recycling technology may get a boost froma California politician. State Senator DonPerata (D-Oakland) advocates a quarter-centrecycling fee on disposable diapers. The taxwould cover both child and adult diapers,adding up to between $12 and $20 over achild’s typical diaper-wearing lifetime.Monies would be turned into grants to funddiaper recycling programs around the state.The bill is co-sponsored by CaliforniansAgainst Waste (Sacramento).

Environmental savings According to Knowaste LLC, the upstreamenvironmental savings of recycling AHPs aresignificant. They estimate that for every tonof AHP waste recycled, 400 kilograms ofwood, 145 cubic meters of natural gas and8700 cubic meters of water are saved.

Roy Brown, president and CEO of the

For more information about Knowaste LLC tech-nology, visit www.knowaste.com or call (905) 568-0334.

Reprinted with permission from Resource Recycling, P.O. Box 42270, Portland, OR97242-0270; (503) 233-1305, (503) 233-1356(fax); www.resource-recycling.com.

company, says, “what makes diaper recyclingthe best diversion option is that it maintainsthe integrity of the valuable raw materials con-tained in AHPs ... Considering the world’sappetite for one-way products, we simplycan’t afford to throw away any high-qualityfiber or plastic resin — there are only so manytrees left.” RR

The greenest diapers of allIn the end, the most environmentally prefer-able way of mitigating the impacts of dis-posable diapers is not to use them at all.Cotton diaper services exist in most largeurban cities, and the environmental savingsare huge. Reusable diapers use about halfas much water, three times less energy, 20times less raw materials, generate 60 timesless waste and cost taxpayers nothing.

Composting diapersThe diaper-producing industry has claimedthat diapers can be composted effectively inmunicipal solid waste composting plants. Infact, they have conducted pilot studies incommunities that they claim have had “verypositive results.” One large diaper companyput a message on its packaging stating, “Thisproduct is compostable in municipal com-posting units. Support recycling and com-posting in your community.”

The problem is that few centralized munic-ipal composting facilities are prepared to han-dle the material. Orga World for example,one of Holland’s larger composting facilities,was receiving absorbent hygiene product(AHP) material from the commercial sectorfor composting. The material was difficult todeal with and, in the fall of 2001, Orgaapproached Knowaste and to develop a planto process the AHPs and Orga to compostresidual sludge.

The problems associated with AHP com-posting can be numerous. The first difficul-ty is the issue of health and safety of facilityworkers’ exposure to fecal matter and otherhuman waste. Second, finished compost iscontaminated by plastic, which incurs addi-tional costs to remove. Third, diapers usu-

ally are tightly bundled-up before thrownaway. This necessitates acquiring a front-end shredder at the compost facility.

Shredding material at the front end meansshredding contaminants, which are usuallypulled out from the finished compost (suchas batteries, metal products, etc.). Onceshredded, extracting the contaminants fromthe back end is impossible, resulting in a less-than-grade compost quality (for a related discussion of plastic film removal from com-post, see also “Skimming the Film Off Com-post” in the February 2002 issue of ResourceRecycling magazine). And finally, end mar-kets for finished compost are fairly undevel-oped all over the world, which may result inanother waste problem.

However, if sustained end markets existand properly designed facilities with the nec-essary health and safety measures are estab-lished, then composting is an option fordiverting small volumes of materials. In fact,Toronto, Canada’s largest city, is in theprocess of rolling out a wet waste programthat will accept diapers, incontinency padsand sanitary products for composting.Because the program is still in its infancy,however, results cannot be reported yet.