Estimating organic waste volumes for composting 

Imagine you’re the facilities manager for a large commercial building or institution, staring at a row of overflowing carts or roll-off boxes sidled up to the wall in the alley or back parking lot. 

They’re filled with crumpled paper, reams of old reports, food leftovers, used coffee pods, an avalanche of plastic bottles and aluminum cans, and pizza boxes with paper napkins stuck to the remnants of a variety of cheese toppings.    

You know all of those discards can be recycled and/or used as compost feedstocks.  Since most of that waste is compostable, diverting the organics from the landfill to composting could save money.   

The problem is, few composting operations will accept mixed waste loads.  The resulting compost is just too contaminated to use and winds up in the landfill anyway.  And if you want to develop an on-site composting project, knowing the volume/weight of compostables influences everything from sizing to siting to process selection. 

Source-separation – removing recyclables and compostables from the disposal stream at your location – is not as difficult as it sounds.  A good education program supported by a healthy dollop of (re)enforcement usually does the trick.   But before investing time, money, and brainpower in the project, you know the decision-makers will want to talk dollars and sense.  They’ll want assurances that the economics work.   

The first step is to determine how many pounds or tons of compostables are being generated each year.  Then, you can begin the planning process and start to gather cost estimates. 

Routes available for developing estimates all come with advantages and disadvantages, mostly related to things like people-power, total generation volumes and required degree of accuracy.  A web search will offer lots of ideas.  Here, we look at 3 broad categories: 

Route 1 – Develop estimates based on published norms and averages 

The easiest, fastest, and cheapest method to estimate compostable volumes is to glean “typicals” and “averages” from the web.   

The U.S. EPA says about 61% of the total MSW stream is made up of food, paper and cardboard, wood, and yard trimmings.  If your commercial or institutional stream is similar, this method could work for you.  Couple this percentage with known weight capacities of the specific receptacle in use, and the result is a baseline number you can use to calculate weekly or annual tonnage.   

Simply convert those gallons or cubic yards to pounds (based on container weight limits), divide by 2,000 to get tons, then multiply that number by .61 or 61%.  This is the estimated weight of all compostables. 

There are also sources that will provide weights based on generation rate per defined unit.  Example: 41 pounds MSW per week per household or 200 pounds per week for each fast food restaurant employee.  Again, convert pounds to tons and multiply that number by .61 for a rough estimate of compostable tonnage. 

Want to count bins or carts?  Contact your waste hauler for specific container sizes/weights or use a more generic number like 180 pounds for a 96gallon cart (from one online resource). 

Just focusing on food waste?  A cubic yard of food waste weighs about .5 tons. 

This method of estimating volumes for composting is probably best for low volume generators, because the total volume and weight of any “error” will be relatively small.  For everyone else, use this type of generic data for rough estimates only. 

You can find charts to help with weight estimates in our SlideShare title:  Estimating volumes of food waste and other organics for composting. 

Route 2  the DIY waste audit 

This method relies on statistically representative random sampling to develop a picture of the total waste stream.  There are several sample size calculators available online to help you get it right, and they come in handy for evaluating validity of other types of surveys, too. 

The following examples were calculated using the SurveyMonkey tool: 

Let’s say you counted a total of 40 trash cans in your office building.  Using a confidence level of 95% and a 5% margin of error, the calculator suggests a sample size of 37 trash cans. 

If you have a larger building with 400 trash cans, using the same confidence level and margin of error, the sample size is 197. 

Trying to pin down the generation volume of a city of 40,000?  The sample size is 381. 

Once you know how many units you need, identify a representative subset for sampling.  A human can do this, but to be totally unbiased in the choice of trash cans, let a computer randomize the list.  Using the 40-can building as an examplecreate a list of all trash can locations in a spreadsheet.  Then randomize the list Randomizing is easy … this site is just one of many with step-by-step instructions.   

Once the list is randomized, use locations 1-37 for your audit: 

  • Assemble supplies (gloves, aprons, scales, etc.) and identify helpers. 
  • Pull all 37 trash cans at the same time on the same day and move to your audit location. 
  • Provide training to any helpers who might not be able to distinguish compostable from non-compostable.
  • Separate can contents into those two piles.  If conducting a full waste stream audit, further subdivide the non-compostables into glass, metal, plastic, etc. 
  • Weigh the compostables pile and divide by 37 (sample size) to get an average weight per can.  Multiply that average by 40 cans (total building) for a daily average.  Multiply the daily average by the number of workdays per year to arrive at an annual weight and divide by 2,000 to convert pounds to tons. 
  • If you’re just doing compostables, you’re done.  Otherwise do the same calculations for each waste group you wish to audit. 

Advantages of this method are improved accuracy and the fact that audits can make good group projects.  But the audit is only as accurate as the volunteers, and auditor safety (masks, gloves, etc.) must be a top priority.  

Also consider, as an alternative to the internal DIY, the resources of a local university where a researcher, class or student may be looking for a project.  Some private companies and governmental entities also offer free audits.  Just make sure they understand the focus is compostables, not just the more traditional recyclables like plastic and glass. 

Route 3 – professional waste audits 

Sometimes, only a professional audit will do.  This will include sizeable and/or toxic waste streams where the expense of professional expertise is warranted.  Typically, these will be engineering firms and other specialists with experience in waste management. 

Professionals can charge by the hour or by the contract.  If taking this route, choose a reputable firm and make sure there is a clear set of deliverables, as well as a timeline, spelled out in the Scope of Work agreement. 

As might be expected, this option can require a healthy budget.  But on the plus side, using professionals can be more accurate than any other when estimating volumes for composting.  If composting costs less than landfilling in your region, the audit may well be a money-saver in the long-term. 

READ MORE: 

Good compost starts with a good recipe 

Whether making a small batch or a big one, following basic instructions will get composting done right. 

While baking relies on an external heat source to trigger a myriad of chemical reactions, and composting generates heat as a result of biological activity, both processes have a great deal in common – including the end result. 

Whether baking cupcakes or making compost, a quality product starts with quality ingredients added in the right amount, at the right time, and in the right order.   

Mess up even one step of the process, and the end product may never be right. 

Ingredients 

Adding a pinch of sugar and 2 cups of salt to a cake recipe (instead of the other way around) could become an inedible disappointment.   

Composting is no different.   

For the process to work as it should, the carbon to nitrogen ratio must be right (25-30:1 by total C and N content, not “brown and green” feedstock volumes) and moisture levels must be in the zone (40-60% by weight). 

Blending 

In baking, improper or incomplete mixing of ingredients can result in gooey or dry pockets within the finished treat.  Batches must be thoroughly blended to distribute ingredients evenly throughout the mixture. 

Goof up a compost blend, and the same thing happens.  Wet or dry pocketsmarbling, and other mixing mishaps mean microbes will not have equal exposure to target compounds, air, or moisture.   

This can create zones of uncomposted materials in an otherwise completed batch, failed laboratory tests, smelly finished product, etc.   

When blending, focus on achieving uniformity in moisture distribution, texture, and porosity. 

Processing 

Convection ovens, equipped with fans that move heated air during the baking process, have become a favored appliance for bakers who once struggled to achieve even baking in older, conventional models. 

But the latest and greatest in kitchen gadgets are no help if temperature settings are wrong.  Heat levels must still be correct to bake a cake or casserole to the center without drying or burning the edges. 

For composting, that zone is 113-160 degrees for initial composting and 70-113 degrees for curing.  The time it takes to complete each processing stage depends on the level of control applied … which is where those fans come to the fore. 

It is possible to compost (and do it well) without an automated aeration system – it just takes more time and trouble.  But it’s not possible to compost without any aeration.  

In nature, it doesn’t matter how long a pile of yard waste or a dead squirrel takes to decompose.  Sometimes, it can take years for nature to work its recycling magic. 

But most composting operations don’t have the luxury of unlimited time.  Speed and effectiveness of the process impacts everything from acreage requirements to the cost of operations.  Managing air flow through the composting mass must be a top priority for any municipal or commercial composting facility that needs to meet both throughput and budget targets. 

Here’s why: 

Remember that 70-160-degree temperature range?  Two types of composting microbes live and work within those zones.  Mesophiles are most active at the lower temps, while thermophiles dominate the higher levels where microbial activity and the resulting biodegradation is quite robust. 

Air flow is the primary mechanism for temperature control within the composting mass.  If temps are allowed to exceed 160 degrees F, thermophiles die off, the entire process crashes, and heat (generated by biological activity) must rebuild to productive levels. 

Every “crash” slows the process.  It’s like opening the oven door every five minutes to check the rise of a souffle — does more harm than good. 

But by using fans to move air through the composting mass, temperatures can be controlled.  More air cools the pile; less air allows warming.  By using sensors linked to microprocessors to automatically adjust those fans to meet specific time/temperature goals, a composting batch can meet regulatory requirements for pathogen kill in a matter of days instead of weeks or months.   

Of course, a manual probe will work, as well, if the budget allows for a person to walk around all day monitoring pile temperatures and making the necessary fan adjustments. 

Cooling/curing 

Food is rarely at its best when consumed straight from the oven.  Most dishes require a cooling/resting period prior to consumption, allowing sauces to thicken, juices to be absorbed and starch retrogradation to “happen.   

Compost, while it can be used fresh once PFRP/VAR requirements are met, is best when allowed to cooltoo. 

This is compost’s curing phase, when temperatures drop into the lower, slower zones preferred by the mesophilic organisms that will finish off the last of the food and bring the composting mass to a stabilized state. 

Farmers may prefer an immature compost because it can offer a slightly higher nutrient value than a more mature product.  But fair warning:  Use a compost before it’s fully cured only when destined for agriculture or other application away from sensitive noses.  Otherwise, wait until the pile offers only the sweet smell of rich, fertile soil before distribution.   

Depending on the initial feedstocks and technology used, the curing phase can last anywhere from a few weeks to several months.  Technologies used during curing can range from controlled aeration to occasional turning of a windrow to static pile. 

What is composting and how does it work? 

Composting is the managed degradation of plant and animal matter under aerobic (with air) conditions.  The process mimics natural decay in a controlled environment to speed up the breakdown of these organics. Composting results in a safe and easy-to-use soil amendment — compost.

Insects and bacteria are examples of the types of creatures that feed on discards like food waste and leaves during composting.  The larger animals tend to use mechanical methods, while the microscopic rely on chemicals to degrade these materials.

This feeding activity reduces complex compounds into simple molecules that are benign and odor free. Compost is used to build and replenish soils, closing the recycling loop for organic matter.  

The only byproducts of composting are CO2 and water;  the process produces no waste requiring disposal.  The CO2 is considered “carbon neutral” since its release during composting is the same as if decomposed by nature.

Most municipal, commercial, and non-profit composting facilities rely on microbes to do the bulk of the organic decomposition.  There are mancomposting methods in use, although outdoor windrows are among the most common.  Earthworms are the primary agents of decomposition in the controlled process known as vermicomposting. 

However, some other processes that have the word “composting” attached to their name in the vernacular may not be true composting processes.

Bokashi composting, for example, is an anaerobic (without air) fermentation process. Anaerobic composting is another misnomer.  Because neither is aerobic, neither is true composting.   Both can biodegrade organics, however.  Unfortunately, anaerobic decomposition may generate unpleasant odors since anaerobes produce mercaptan during biodegradation. (Mercaptan is added to odorless natural gas to give the gas its distinctive rotten egg smell.)   

Composting digestate, the by-product of energy extraction using anaerobic digestion, increases both the market value and uses for this waste material if managed for quality compost production.  

While neglected composting piles have been known to “go anaerobic,” too, a well-managed composting process — one that keeps the piles aerated — will not generate unpleasant odors.  Any odors present in the incoming feedstocks will be quickly neutralized, too.

Food waste collection: Thinking outside the trash can

Food waste collection can be a major hurdle for communities hoping to recycle curbside.  But might the real problem be not the what, but the how?  Is it time to think outside the trash can?

Let’s ponder this a minute.   

Waste 360 recently spotlighted grassroots recycling as a viable alternative to mainstream systems.  The article pointed out the actions of municipalities that, years ago, may have been too eager to turn successful, local recycling efforts over to “big waste haulers.”

The entrepreneurial efforts and business models of food waste collection outfits like CompostNowNOPE, and Compost Cab seem to be working in their respective service regions.  Instead of disrupting existing “Trash Day” collection systems and practices to include source-segregated food waste, these types of operations bypass the big trash truck with a service built on local-centric collection models that are meeting with success in multiple jurisdictions.   

Commercial composters, both large and small, have already demonstrated profitability in providing direct services to high- and low-volume waste generators, too. This success certainly proves that bypassing conventional collection systems is viable.

Looking at the world’s most successful bottle/container bills, we see return and recovery systems totally divorced from trash collection with capture rates approaching 100 percent.  While bottlers and other manufacturers of containerized products have been known to fight these types of programs, deposit and return systems do work. And they appear to work best when deposit amounts encourage those returns.

So, as the U.S. scrambles to rebuild and reshape its recycling infrastructure in the wake of the China debacle, could the long-abandoned local route to resource recovery of recyclables – residential food waste included – actually offer the better solution?  

Should food waste collection be a local thing?

Maybe, the decades-old struggle to integrate recycling within a system designed for mass disposal indicates the entire approach is flawed. Closely associating food waste, plastics, etcetera with trash as a first step to recovery means recyclables must be rescued from the waste stream before recovery can take place. Is this logical?  Is it efficient?  

Adding methane capture systems to landfills in an attempt to neutralize the damaging impacts of anaerobically-degrading organics just adds complications and expense for managing a material that shouldn’t be landfilled.  Similarly, for plastics and other recyclables, the better solution may lie in diversion at the source, not the transfer station.

Minus putrescibles/recyclables,  curbside collection of the real trash might be reduced to once a month (or less).  This disposal stream would be much, much smaller than current volumes … and clean.   With lower fill rates, existing landfills should last longer and cost less to manage, too.

When recyclables are funneled through and filtered by trash systems, does it make diversion more difficult than it needs to be?   Have we been going about recycling all wrong?

What are your ideas for getting recycling right?

Attract professional composters to your city’s waste management table 

Composting high volumes of source-separated organics (SSO) is not for the faint of heart.  It takes skill, experience, and science to recycle one of the messiest urban waste streams.  But while composting done right doesn’t come cheap, it is possible to build modern composting infrastructure without public financing. 

Instead of bemoaning a lack of composting infrastructure and doing nothing about it, municipalities and regional authorities can set the stage for organics diversion.   

The result?  Some of the biggest and most experienced composting companies will compete for that business. This delivers a big win for the host community: 

  • No well-intentioned but flawed “solutions” from designers and technology providers with no knowledge of biochemistry and no hands-on experience in the day-to-day operation of industrial composting facilities.  
  • No major issues with regulatory permitting when other facilities of the same type are running successfully elsewhere. 
  • … and here’s the biggie – no public financing required if the population base within 40-60 miles is large enough and the local landfill tipping fees are at or above national averages.  A community/region of around 50,000 could generate a sufficient volume of organic waste to make commercial, high-rate composting economically viable.  (View: Estimating volumes for composting) Private ownership means private financing.  Public/private ownership can also result in private financing if the public entity brings enough to the table to make joint ownership attractive to the private entity.   

But what about – 

  • Facility failure?  Structure the contract to include an option for public takeover should the owner fail to make a success of the project.  
  • Odors?  No matter the technology choice, most climates will require an indoor operation with a good biofiltration system — combined with preventive/preemptive management practices — to solve the odor problems associated with composting putrescibles.  Consider containment, collection, and treatment of air from all active work zones — off-loading to curing.  Typically, if the product has been properly composted and cured, it can be stored outdoors.  However, to preserve product quality, some manufacturers may opt for covered storage here, as well. 
  • Leachate?  Correct blending and indoor processing all but eliminate leachate as a management headache.  But do require RFP respondents to address the issue in their respective proposals. 
  • Product stockpiles?  Make sure the successful respondent has a proven track record in marketing compost in similar markets.  Just remember the sale of soil products tends to be seasonal.  Suitable acreage for large stockpiles must be included in the site plan.  Those stockpiles should dwindle significantly during the planting season(s).  But as a safety net, require a provision for distribution of volumes exceeding market demand after a reasonable market development period. 

Foster and promote compost use 

Composting is efficient, cost-effective, and the only technology offering true sustainability for biodegradable waste.  Returning organic matter to the soil to complete the recycling loop is what makes composting and compost use a sustainable system.   

But policymakers tend to get so caught up in the diversion of organics that they neglect correlating mandates for compost use. 

Compost isn’t just for farmers.  A quality compost can be used by anyone, anywhere – even urban/suburban areas: 

  • Lawns, gardens, and greenspace 
  • Parks, sports fields, and other recreation areas
  • Roadside and rest stops
  • Utility easements and rights-of-way
  • Rainwater catchment zones and pathways 

Parallel to composting infrastructure development, craft internal and external guidelines, policies, and programs to encourage regionwide compost use.   This will not only help build a product market, but also reap financial benefits to the municipality in the form of reduced costs related to stormwater management, synthetic fertilizer use, etc.  

Is composting food waste wasting food?  Until recently,  it’s a question that didn’t get asked.

Recycling organic matter back to the soil is supposed to be a long term, environmentally prudent, carbon sequestration practice — right?  Glowingly green.  Halo worthy.  Self-righteously gratifying.

Unfortunately or fortunately, depending on one’s viewpoint, folks are beginning to question all food waste, including the composting of former edibles.  

If composting was once a way to waste food without guilt, it is no more.  Except for the egg shells, potato peels and the like, that which was once edible food, if allowed to become fodder for the compost bin, is not consumed.  It does not feed anyone.  Ergo, it is wasted. 

Things like that fuzzy green stuff discovered in a leftover container in the back of the fridge, the carton of curdled milk, and the shriveled asparagus stuck to the bottom of the vegetable drawer means the cook prepared too much or a diner ordered too much at the restaurant or the family opted for pizza delivery while groceries languished in the pantry and fridge.

Buying too much prepared food, failing to prepare purchased ingredients, or cooking more than the family or customer will eat wastes food. The fact that the waste is composted does not negate the considerable negative environmental impacts required to get that food from farm to processor to kitchen to table — only to bypass a plate and wind up in the compost bin.

Yes, composting wasted food is far better than most alternatives.  But a critical look at wasteful habits could identify opportunities for improvement.  Chances are, even the most dedicated composting kitchen — whether residential, institutional, or commercial — can find ways to further reduce food waste while still generating enough scraps and culls to feed all those critters living in the compost pile.

READ MORE:  Can I compost oil and cooking grease?

Can I compost cooking oil and grease?

Is it possible to compost cooking oil and grease?

A lot of cooking fat, oil, and grease (FOG) goes down the kitchen drain.  Commercial kitchens install grease traps to collect the mess before it enters public sewer systems, diverting this waste to alternate disposal.

But the typical home kitchen does not, and the practice can clog pipes and negatively impact wastewater treatment systems.

Yes, it is possible to compost FOG.  But for the home composter, volume reduction and reuse is recommended as the first and best management strategy.  Adopt some of these kitchen practices to reduce and reuse to minimize volumes requiring composting or disposal:

REDUCE   

  • Opt for the oven or air fryer instead of deep or pan frying.
  • Spray oil onto food or into pans to lightly coat before cooking instead of pouring oil into the vessel for significant volume (and calorie) reductions.
  • Wipe cooking vessels with a paper towel before washing to remove excess oil.

REUSE

  • Many fats and oils (bacon, peanut, etc.) can be reused.  Cool and pour through a coffee filter or strainer into an airtight container and store in the fridge for up to a month.  
  • Allow cooking juices to cool.  Skim/remove the fat that congeals on the surface and freeze to use later to flavor veggies, soups, etc.   

RECYCLE

  • Check with your public utility to see if there is a FOG drop location in the community.
  • Add cooking grease to the food waste bin if your community composting operation can accept it.

COMPOST AT HOME

  • Small  volumes (up to 1 cup) of plant-based oils are best for home composting.  Simply pour over pile and blend in.  
  • Also compost the paper towels used to wipe oil from pans and kitchen surfaces.      

DISPOSAL

  • Pour waste oil into a non-recyclable can or bottle.  Seal prior to disposal. 

Is it really a good idea to make compostable waste go away and never come back? 

Each year, taxpayers collectively spend millions of dollars to burn or bury compostables.  Much like a tribe of ubiquitous Gollums, they just want garbage — the biodegradable and putrefying fraction of the municipal solid waste stream – to go away and never come back. 

The desire to make disagreeable discards disappear into fiery furnaces or burial mounds is understandable.  But is it wise?  Is it fiscally responsible?  Is it really a good idea to make organic waste go away and never come back? 

Nature recycles everything 

Rocks weather and erode, creating sediment. With heat, pressure, and time, that sediment becomes rock again.  Plants and animals feed and drink from the earth, die, and decompose to replenish the soil that will sustain future generations of flora and fauna.  Water drops from the sky as rain, filters down to aquifers, upwells and evaporates back to the clouds to fall once more. 

In a fantasy land, it may be possible to keep using resources without a thought to replenishment.  But in the real world, organic waste – the decaying residuals of once-living things – must be recycled back to the soil to maintain life-critical soil functions.   

Some seem to think the destruction of organics to make energy is more important than rebuilding soil.  But pushing an organic-waste-to-energy agenda by sacrificing the soil makes no sense. Humans managed to survive for millennia without electricity and centralized energy systems.  Without soil’s life-essential contribution to food and clean water, people face extinction in weeks.  

So, which is more important, energy or soil? 

Make energy and rebuild soil?   

Organic waste from developed societies includes all types of vegetation, food, manures … even compostable plastics.  When turned into a quality compost, these once-lost resources can be used by anyone anywhere to replenish depleted soil.   

Happily, making energy and building healthy soil does not have to be an either/or proposition.  It is possible to extract energy from organic waste without destroying the beneficial properties that make it valuable to soil.   The organic waste streams from these processes can then be used as feedstocks in the manufacture of compost products. 

Unhappily, energy production from biomass is one of the most expensive ways to make energy.  Even solar and wind power can be more cost-effective. 

Furthermore, bioenergy technologies based on anaerobic digestion of organics are still too pricey to be practical in many places.  Where they do exist, the waste stream (digestate) is not always put to highest and best use (i.e. composted).  Instead, residuals may be landfilled or relegated to low-dollar-value reuse. 

But one day, as more communities opt to restore natural soil replenishment cycles and energy generation technologies become more efficient, extracting energy from biomass, followed by composting and compost use, can become the system of choice for organic waste management. 

In the meantime … 

The importance of healthy soil 

Where humans live, topsoil has been scraped away or eroded.  Nutrients are used up.  Compaction has destroyed the pore spaces essential to the transport of air, water, and microbes.  Without a regular infusion of new organic matter to correct these deficiencies, soil dies.   

There are lots of processes for generating energy, but there’s only one way to replenish disturbed soils in developed areas – feed them a good, wholesome diet derived from organic waste converted into compost.   

From farms to lawns to sports fields, soils require periodic applications of compost.  There’s no other way to easily and economically provide soil with everything it requires to retain water, nurture vegetation, and create the type of environment soil microbes need to support nutrient uptake, contribute to disease resistance, and degrade pollutants. 

The best news? In many metropolitan areas, efficient, high-rate composting – the type needed to successfully manage big, urban waste streams – costs no more than landfilling or incineration.  Often, recycling at a modern, industrial composting operation can be more affordable than traditional disposal.   

Composting makes organic wastes go away, but they come back as enriching soil amendments.  Biodegradables need to keep recycling, just like they have since the beginning of time. 

Breaking the natural soil cycle by incinerating or burying compostable waste is a bad idea that should go away and never come back.

VIEW THE SLIDESHARE:  Addicted to convenience

How to make compost fast

The desire to make compost fast can be driven by space restrictions, the need for more product, or simple impatience.   It’s a common goal for composters everywhere, from the backyard to industrial facilities.

Unfortunately, wishing will never make it so.  The speediest course from raw feedstock to finished quality compost is a series of steps controlled by the person doing the composting.  Skip or bungle just one, and biodegradation could slow or even grind to a halt.

It doesn’t matter whether you make compost by the tumbler or by the ton.  If you want to make compost fast, follow these steps:

  1. Consider carbon-to-nitrogen (C:N) ratios when mixing every batch.  Base mixes on the C and N percentage of each feedstock, not feedstock volume – it’s not buckets of “brown” to buckets of “green.”   Learn more about calculating C:N ratios.
  2. Get the blend right with uniform particle size, good porosity, no clumps or marbling of feedstocks.  
  3. Maintain a desirable moisture level throughout primary processing.  Don’t expose the composting mass to weather or allow it to dry out.  Add moisture, as needed.   Learn more about composting moisture levels.
  4. Keep air moving through the pile.  This allows microbes to breathe and removes excess heat.  Invest in a temperature probe and adjust air flow to maintain ideal temperatures.       

Master these basics to make compost fast.

Does composting release CO2?

Carbon dioxide (CO2) emissions from the composting mass are classified as biogenic. This means the same amount of gas is emitted during decomposition whether the organic material is composted or degrades in a natural setting.  Therefore, these emissions are considered carbon-neutral.

Compared to waste management alternatives, it’s the best of the bunch.

Other emissions sources, however, like those from equipment operation,  do add to the size of a composting facility’s environmental footprint.  These are nonbiogenic, a.k.a. anthropogenic, emissions.

This factsheet provides a good topic overview that includes values for helping composting operations with emissions calculations.