Workshop3 Composting

Sustainable CUNY

 Composting:
 Process
 Advantages
 Methods
 Issues

Process
 What can be composted?
 food waste
 food scraps, coffee grounds, tea leaves, eggs shells, shredded papers,
dairy, bread, vacuum cleaner contents, canned fruit & vegetable liquids…
 meat / fats not encouraged
 yard waste
 grass clippings / leaves / bark / dead wood / prunnings…
 certain compostable plastics
 How does it work?
 bacteria & other micro-organisms break down waste
 two outcomes – mulch or humus
 oxygen vital to the process (aerobic decomposition)
 no oxygen = anaerobic decomposition = methane (a GHG)

Advantages
 GHG reduction:
 1 ton composted waste = approx 1 metric ton reduction in GHG
 waste volumes a factor in your campus’ emissions calculation
 Reduced waste haulage costs:
 lower volumes = lower costs
 waste haulage arrangements & costs vary across CUNY
 Usable end-product:
 mulch or humus can be reused on campus grounds
 can be donated / sold locally (parks, community gardens…)
 Educational value:
 inclusive & participatory (esp. traditional methods)
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Methods
 Pulping:
 not strictly composting – simply reduces volume of waste
 output can be composted or discarded
 machine = requires water & electricity to operate
 Machines that do the work:
 minimize need for hands-on effort
 volume of waste key factor in adopting tech solution
 outlay costs absorbed by reduced haulage costs?
 sufficiently large / steady stream of waste produced to feed machine?
 a power source & water source usually necessary
 space requirements vary depending on the technology
 initial training necessary (use & maintenance)
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Pulpers
 Characteristics:
 can reduce food (& yard) waste volume by 80%
 can reduce weight by 50%
 can convert up to 1,000lbs of waste to pulp in 1 hour
 increases the capacity of your composter
 increases the quality of your compost
 available in sizes from 500 lbs/hr
 $15,000 - $50,000

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The Rocket
 turns food & yard waste into compost in 14 days
 successfully used by many British businesses and universities
 catching on in USA (St. Johns in NYC)
 can be operated in a limited amount of space
 Smallest machine is 2.0m long, 0.7m wide, 1.4m high
 Largest machine is 6.0m long, 1.0m wide and 1.8m high
 available in 4 sizes
 can process 50 to 7000 liters of organic wastes per week
 little manual effort required
 no odor, no rodents and no insects
 $18,000 - $40,000

BioHiTech
 turns food waste into waste water which is flushed into the
sewage system
 used in restaurants, hotels, supermarkets, universities
 available in 3 sizes (400lbs – 1,200lbs of waste)
 largest machine can process 1 ton of waste per day
 minimal operational training needed – machine runs itself
 no permitting or code issues
 no odor or rodents
 placement assessed as part of service (waste area / kitchen)
 can buy or rent
 $23,000 - $40,000 (excl. service agreement)
 $1,000 per month rent incl. service agreement (minimum 3 year lease)

Methods
 Traditional Methods:
 can be done on any scale
 use containers made from numerous types of material
 wood, chicken wire, pallets, plastic bins, old street bins…
 can mix food & yard waste
 layering of waste types & aeration important to process
 requires turning (approx. once per week)
 speed of process varies depending on seasonal temperature
 3 weeks in summer under ideal conditions
 several months in winter
 most engaging / participatory option
 students & staff can add their food waste or get involved in the process

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Issues
 Rodents:
 genuine issue
 machines claim to reduce this problem
 Measuring food waste:
 critical in determining value & method of composting
 5-day week / reduced activity in summer will impact waste
quantities
 Cooperation of dining service vendor:
 kitchen-side food waste easiest place to start
 education / cooperation of key staff necessary

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Issues
 Composting partnerships:
 parks, community & botanical gardens accept donations
 DSNY runs the ‘NYC Compost Project’
 information / resources / training
 http://www.nyccompost.org/contact.html
 some companies in NYC take organic waste for composting
 http://www.actioncarting.com ($0.06 per lb)
 http://www.filcocarting.com ($15 per 23 gallon container)

 Including students & staff:
 a topic which can engage & educate (esp. traditional forms)
 later phase in program = collection of their food waste
(cafeterias / classrooms / office areas)
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Workshop3 Composting

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