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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: 

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?

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?

Food waste mandates are only the halfway mark 

Compost use gets organics recycling to the finish line 

Unlike a decade ago, when food waste mandates were few and far between, there is a flurry of activity these days focused on diverting food waste and other residential/commercial biodegradables from landfills and incineration. 

From the U.S. to Italy to northern India, the movement toward more sustainable management of organic waste from households and businesses is real and gaining momentum. 

But while laudable, there’s a big piece missing from some of these programs — mandated compost use.  Just making compost isn’t recycling.  The product must be used – returned to the soil – to be recycled.  That’s what makes the system “sustainable.” 

Landfilling organics isn’t sustainable because they’re buried.  Any thermal or other waste-to-energy (WTE) technology that destroys organics isn’t sustainable, either, no matter how hard technology providers try to paint them as such.  The feedstock – municipal waste – may be considered a sustainable source, but the management system is not. 

A possible exception is biochar, carbon-rich, charcoal waste material produced by pyrolysis that is sometimes used as a soil amendment.  However, not all biochar is right for this type of reuse.  It doesn’t offer as many benefits as compost, and — since the use of biochar is relatively new — there is a lack of research related to its long-term use.  While pure biochar is made from organics, of specific concern is contamination resulting from WTE biochar processes that use unsorted municipal solid waste as feedstock.  

But whether biochar or compost, the truth bears repeating — recycled organics must be used to feed the soil for a sustainable system to exist.  This is the only way to close the recycling loop for organics. 

Going the distance with food waste mandates

Football players don’t move the ball to the 50-yard line and then stand around waiting for the pigskin to get itself into the end zone. 

Establishing a curbside or drop-off program for source-separated organics is a good first step … but it’s only half the distance to the goal.   

The finish line for organics recycling is compost use.  Anything a community can do to encourage that use is important.  But sometimes, it takes more than education and outreach to get the ball rolling. 

When governmental entities write ordinances and project specifications requiring compost use, good things happen.  By creating early markets for quality compost productseveryone from green industry pros to stormwater managers to homeowners can clearly see the benefits of amending soil. 

This demonstration leads to voluntary compost use through the manufacture of quality products and product sales to high-value markets.  Product sales, not giveaway programs, is what will keep composting facilities – public or private – economically sound. 

Any community considering organics recycling needs to think about the end game.  To ignore the ultimate goal is to win the battle, but lose the war for organics recycling.  

READ:  Food waste diversion — it’s time to pursue alternatives that make environmental and economic sense

Got food waste?  We’ll take it. 

Here’s what you need to do to get ready for food waste composting 

(Also view WE WORK FOR FOOD WASTE on SlideShare) 

Not every composting facility is using a technology with the oomph to take on the full range of biodegradables common to food waste.  McGill is one of a handful across the county that will accept it all. 

McGill accepts food waste, including dairy and meats.  We take certified-compostable cups and other serviceware, too.   Dirty napkins and pizza boxes, paperboard/cardboard, broken pallets  – toss it all into that container bound for a McGill composting facility. 

But there are a few things you need to do before jumping feet first into organics diversion. 

  • Composting generally costs less than landfilling.  Look around for any and all biodegradable wastes that can go to composting along with that food waste.  
  • Get a handle on total generation volumes of biodegradables.  You can’t get a quote, plan for storage or make meaningful forward progress until weekly or annual generation rates are determined.  Our Estimating volumes for composting SlideShare title can get you started on either a DIY or professional waste audit. 
  • Get a quote for composting services based on the total compostables volume. 
  • Figure out how you’re going to separate the compostables from the other recyclables (plastic bottles, aluminum cans, etc.) and trash.  The composting stream has to be “clean.” That means no non-compostables.  Contamination makes the compost unsalable.  Because the ability to derive revenue from compost sales is one reason composters can offer lower tipping fees, intake customers (like you) are the beneficiaries of diligent source-separation.   
  • Identify vendors for compostable serviceware and other products.  Determine costs to switch to an all-compostable food service environment.  Going all-compostable will eliminate most common contaminants, scratch the need for multiple trash and recycling receptacles in food service areas, reduce the cost of penalties for contaminated loads, and make enforcement of separation policies so much easier.    
  • Develop a collection, separation, and storage strategy. 
  • Confirm all assumptions, develop and finalize the project budget. 
  • Develop and initiate a training and enforcement program for participants, whether they be employees, customers, or residents. 

If you’re in a region served by a McGill composting facility: 

  • McGill will haul your food waste and other compostables if you generate enough to fill a big roll-off container or tractor-trailer load every few days.  Some health departments may have rules governing the required frequency of food waste collection.  Check with yours.  Regardless of local rules, you don’t want food waste sitting around for long periods of time.  If you are a low-volume generator, contact a third-party hauler who specializes in bin and cart collection.  Your public works department or local/state recycling coordinator may be able to give you some names.   
  • One cubic yard of food waste weighs about half a ton.  Our minimum load requirement is 40 tons.  We’ll haul smaller loads, but you’ll be charged the 40-ton minimum.  That’s why it may pay for you to look around for other organics to toss into the composting bin along with the food waste. 
  • If you want to haul yourself, take a look at McGill’s requirements for vehicles and drivers. 
  • To find out if there’s a McGill facility near you, find our locations here. 
  • Here’s how to contact us. 

If you’re not in a region served by a McGill composting facility: 

To find a composter in your area, contact state and local recycling coordinators or solid waste divisions.  There are also searchable directories online, like Find a Composter. 

Confirm what these operations will or will not accept, then base your waste audit and separation strategy planning on those findings. 

To compost it yourself: 

For high volume generators,  McGill offers package plants beginning at 35,000 tons per year throughput.  

But for low volume generators with sufficient space and people-power, on-site composting may be an option, offering the resulting compost for sale or giveaway to customers, employees, or the broader community. 

If exploring this route, do yourself a big favor and eliminate open-air composting as a consideration.  The last thing any company needs is negative PR from an outdoor compost pile gone wrong.  Opt for some kind of enclosed or in-vessel system, like those offered by Green Mountain Technologies.   

Also know that composting beyond the backyard requires professional management.  It may also require state or local permits.  For program stability and to ensure both paperwork and process are done right, even a small community food waste project relying on volunteers for the bulk of the labor force should consider putting a paid, trained, and certified specialist in charge of the composting operation.   

food waste composting includes biodegradable plasticsHarvesting practices, processing systems,  grocery store discards, food prep,  and plate scrapings all contribute to food waste.

According to the U.S. Environmental Protection Agency, 2010 saw the generation of 34 million tons of food waste, almost 14 percent of the total municipal solid waste (MSW) stream.  Only 3 percent was recovered/recycled.  The remaining 33 million tons was wasted, the largest fraction of the total MSW stream to be landfilled or incinerated.

That same year, the U.S. composted about 20 million tons of waste. To compost all food waste currently landfilled or incinerated, we will need to more than double current capacity.  A commitment to zero waste for all organics pushes capacity requirements even higher.

But there is plenty of room at the composting table.  If the industry is to meet the challenges of zero waste, we need to fill those empty chairs.  Fortunately,  interest in collecting food waste from local restaurants, grocery stores and the like is on the rise.

In fact, every now and then, some hopeful composter will contact us.  They seek advice about getting into composting on the community level.

We always offer encouragement, and for some very good reasons.

The ‘greenest’ option may not be viable

Some of us have been environmental activists long before green became everyone’s favorite color.  We know —

  • collecting food waste from the neighborhood,
  • composting it in the neighborhood, and
  • using it to grow food on urban farms in the neighborhood

may be the most desirable option from an environmental standpoint.

But these types of micro-projects are not always practical or particularly viable. Recycling things like plastics, metals and glass is an expensive proposition.  So is recycling food waste – if you want to do it right.

The economics and/or logistics of composting sometimes prohibit action on the neighborhood level.  When that happens, a regional solution can be the best choice for crafting a disposal-to-reuse cycle that works.  Networking with proactive individuals and groups within communities presents opportunities for companies like McGill.

Voluntary collection requires route density

Most of our existing customers generate by-products and residuals by the ton.  But hauling services for low-volume commercial and residential generators are another matter.

Generally, volunteers don’t provide the volumes or route density needed to make the economics work for big tonnage haulers.  Curbside collection requires recycling mandates.

However, smaller companies and community groups are stepping up to the “plate” to fill this gap with curbside services.  They are collecting food waste and other organics by the bin or cart, transporting to permitted composting facilities like McGill.

National Organic Process Enterprises (NOPE) out of Richmond, Va., and Compost Now, based in Raleigh, N.C., are just two companies on our radar.  And there are many more popping up across the country.

It seems to be a successful model for enviropreneurs when the composting facility is located close to a metropolitan area.  No need for food waste transfer stations.

The homeowner or business is able to recycle food waste.  The collection entrepreneur builds a viable business.  We use the material to make compost.  The homeowner or community uses the compost to improve soil.  Everybody wins when we all work to lock the recycling loop for organics, including the environment.

Obviously, there is plenty of room at the composting table for operations of every size. From backyard to community to regional scale, each fills a specific niche.  All will be needed if we, as a nation, are going to stop wasting such a valuable resource.

Up next:  Food waste composting – not as easy as it sounds, not as hard as it seems.

art-pencil-apple-dividerWhen it comes to diverting food waste , there’s still a long row to hoe.

North Carolina released a 2012 study revealing an annual food waste generation rate of over a million tons in the state.  The volume represented at least 12 percent of NC’s municipal solid waste stream. It was slightly lower than the U.S. as a whole, which was around 14 percent in 2010.

As a nation, we’ve made solid progress in recycling some materials.  But food waste isn’t one of them.  The national food waste recovery/recycling rate is only around 3 percent.  What remains — 33 million tons — goes to landfills and incinerators.   North Carolina is doing a bit better than that.  It diverts about 60,000 of those 1 million-plus tons generated or about 6 percent.  But that still puts 94 percent into the disposal stream.

Scott Mouw, North Carolina’s recycling program director, calls food waste “the next frontier for reducing landfill dependence.”  We say it’s that and more.  Food waste, when composted and used as a soil amendment, is a key to reducing stormwater volumes and related pollution.  Its use cuts dependence on chemicals and foreign oil, saves water, and so much more.

Landfills and WTE — diverting food waste?

Burning and burying resources are wasteful and environmentally-unfriendly practices.  Plus, these types of disposal can be more expensive than recycling systems with composting as the core technology.

It’s time to abandon the exuberantly wasteful practices and technologies of the old century and get on with the new.  Building a modern waste management infrastructure is both environmentally and economically responsible.