Informing Organic Waste Collections

23rd April 2018

A food waste collection trial we designed with the Italian Composting Association carried out in New York City has demonstrated how to increase the capture of organic waste from multi-family buildings by over 400%.

Stuyvesant Town (StuyTown), one of the largest developments of residential buildings in Manhattan, New York City, wanted to know how to best increase participation in the organic waste recycling program offered to its residents. It turned to a team of experts including the Italian Composting Association, Novamont, and ourselves, for help.  The team worked with StuyTown to design a trial which would test how different service factors impacted on participation levels, as well as on the quantity and quality of material collected.

Each of the 89 buildings in StuyTown is serviced by a 23-gallon organic basement bin, which residents can access by elevator. These bins which are lined with a large Mater-Bi compostable biobag, to help with efficient emptying, are collected by the NYC Department of Sanitation three times a week.

Picture caption: Kitchen caddy, biobags and information material

Six buildings were selected for the trial, and for four weeks prior to notifying residents about its commencement baseline data was gathered on the weight, and character of organic waste being collected and also the level and type of contamination. Running the trial across six different buildings allowed for six new configurations of service factors to be tested.  Figure 1 summarizes the service provided to each building during the trial.

Figure 1: Service by building

The trial lasted for eight weeks, during which time data was gathered on weight, character and contamination of the food waste being collected. The highest performing buildings were those provided with bins on each floor (figure 2). Building Four achieved a +190% increase in material quantity collected and building Six achieved a +420% increase which equated to a capture rate of 65%. This suggests that convenience of drop off point is an important factor in driving up capture rates. Noting that it is not always possible to provide floor bins, providing a supply of compostable Mater-Bi biobags for a sufficient period to enable behavior change was also found to play an important part, with Building Three showing a +100% increase in material quantity equating to almost 45% of all food waste in the residual bin.

Figure 2: Participation rates by building

Contamination levels did not exceed, on average, the pre-trial rate of below 4% despite the floor bins being located close to buildings’ trash shoots. Biobags were found to be the most effective tool for reducing contamination, with those buildings provided with a continuous supply (buildings Three and Four) achieving on average the lowest contamination rates. These buildings also had the lowest number of plastic bags within the organic stream.  When surveyed, residents later confirmed that they had found the convenience of the floor bins to be the most helpful aspect of the trial, with biobags named as the second most helpful.

The trial was commissioned by Novamont, the company producing the compostable resin Mater-Bi and Biobag used in the trial. StuyTown undertook all of the vital waste characterization work in addition to hosting the trial.

The Head of our New York Office Sarah Edwards said:

“The trial demonstrated the importance of making participation as easy as possible.  The floor bins made dropping off separated food waste convenient, and the biobags and caddies provided a visual reminder to participate and helped dispel myths around odor and flies.  The results and learnings from this trial are applicable to many different types of multi-family buildings’.