Posts

ASP composting – penny wise and dollar smart

There was a time in composting’s history when a method or technology based on anything more sophisticated than simple turning might have been considered risky and experimental.

A basic window operation was also cheap.  So choosing this low-tech option seemed like smart thing to do.  But that was long ago, and that penny wise start-up may now be a dollar foolish facility.

Nowadays, the outdoor windrow is composting’s equivalent of a pedal car trying to keep up on a highway populated with Teslas.

And as for the price tag, by the time the owner wastes an inordinate amount of time and money battling –

  • flies,
  • leachate,
  • failed lab tests,
  • equipment issues,
  • Mother Nature,
  • and a mountain of unsellable or low value product,

…that bare-bones facility doesn’t look like such a bargain.

Time-tested, proven technologies now exist that best the outdoor window in almost every production category, delivering rapid, predictable processing and high compost quality.  

Save time.  Save money.  Generate significant dollars from the sale of compost products.  What’s not to like about ASP composting? 

Yet, the majority of all composting operations in the US are still outdoor and low tech.  Nearly 60% are yard waste only facilities.  Not food waste and yard waste.  Not biosolids and yard waste.  Just yard waste.

They may have been cheap to build, but they’re not designed or equipped to handle the modern urban waste stream.  They’re not generating maximum revenues for their owners.  In short, those beleaguered owners are leaving money on the table.

When a region is not composting all of its organics (W/WTP sludge, FOG, food waste, yard waste, etc.) and professionally marketing a quality compost, it could be spending too much for multiple organic management and disposal systems, too.

To be at their most efficient and cost effective, public, private, and nonprofit operations can reduce costs and improve revenue generation by upgrading that tired, under-performing windrow system. 

And even if your windrow operation is chugging along without major headaches, it is possible to add more dollars to the bottom line while whittling away at operating costs.

Step 1 – Upgrade to ASP

Outdoor windrow composting is such a cheap and easy way to get started in the business.

But it’s only that – a start.

At some point, anyone who is serious about taking on a feedstock stream that includes high-moisture and/or highly-putrescible organics will want to consider a faster, more predictable technology for converting waste into a salable product.  And that often points to some sort of aerated static pile (ASP) system.

ASP composting is not one size fits all.  These systems can use fans to pull or push air through a compost pile.  Some might passively aerate by embedding perforated piping in the composting mass to improve air flow.

This natural or forced movement of air replaces the windrow turner.  Aeration speeds up biodegradation by keeping the microbes happy, creating and maintaining ideal oxygen and temperature levels within the composting environment.

When feedstocks are properly blended, ASP also ensures even degradation rates throughout the composting mass, making the process (including throughput rates) more predictable.

The same air movement also removes excess moisture, eliminating leachate issues, too.

Process control options range from manual to fully computerized temperature logging and aeration management.

Converting to ASP composting is one of those expansion activities that can be completed incrementally as time and budget permit.

Set up a test unit, tweak until everything is right for your operation, then build out the system.

Step 2 – Eliminate weather as a process influence

Unless you are operating in a perfect-for-composting climate, sooner or later you’ll want to put yourself in control of your process, not Mother Nature.

Yes, we are talking covers, enclosures, buildings, encapsulation … anything that will lessen weather’s influence over the process and the product.

The more control a manufacturer can have over the composting environment, the greater the potential for the production of top quality, high-value compost.

Make note of the fact that we used the word “potential,” because humans can manage to muck up just about anything.  In truth, most problems at composting operations of any type are the result of human failure, not design or technology issues.

Therefore, each preemptive design or operational choice that removes both weather and the human factor from any composting phase takes the entire process one step closer to reliable perfection.

This means stationary piping and fans beat a windrow turner, a building is better than open air, automated monitoring and airflow control is superior to manual thermometer readings and passive aeration.  

And as the processing environment becomes tighter and more secure, compost quality improves.  So does a manager’s ability to predict and control throughput.  Composting becomes a true manufacturing process.

Who should consider ASP?

These days, it’s possible to find aeration features on home composting units.  So it would seem composting projects of all sizes and descriptions can benefit from ASP augmentation.

From the 3-cubic-yard pile at the community garden to a 100,000 TPY super-sized facility, ASP could make sense for your operation if you want to –

  • Simplify the system,
  • Take the guesswork out of processing,
  • Reduce management time/labor costs,
  • Reduce equipment acquisition and maintenance costs,
  • Cut space requirements or process more in the same footprint,
  • Add biofiltration,
  • Minimize nuisance issues and complaints,
  • Improve compost quality, and/or
  • Improve environmental protection.

If a community project has a cadre of volunteers showing up every few days, turning shovels in hand, ASP could spoil all the fun.  But if the project coordinator finds him/herself standing there all alone on turning day, contemplating the purchase of a skid steer loader to help with the heavy lifting?  ASP could get the job done at a fraction of the cost.

An outdoor windrow operation may be able to accommodate a few small loads of food waste every week.  But what happens in a few years when that volume turns into several loads day, then several loads an hour?

And consider the “perfect” windrow composting site.  Years ago, it was sitting in the middle of nowhere surrounded by cows and cornfields.  But today, owners of those facilities may see the roofs of yet another new housing development peeking through the trees.

Like it or not, populations are growing and more folks now live in metro areas than rural.  Urbanites are spilling out into the countryside.

Why wait for the inevitable nuisance complaints to start rolling in when you can easily reduce the active footprint and increase vegetated perimeter buffers to keep your operation off your new neighbors’ radar?

Get yourself a kick-ASP system

With ASP composting comes serious control over the composting process.  The delivery of air to the composting mass makes it ideal for processing high-moisture feedstocks like food waste.

But there are many options that should be considered before settling on the specific elements of an ASP composting unit.

Because no single system is right for everyone, matching the system to the operation ensures those improvements will meet processing goals without overspending.

For a small, low throughput project, a good USCC workshop might be all that’s needed to set the owner on the path to success.  But for anything larger, a knowledgeable consultant or system designer could be a valuable member of the conversion team.

But a few words of caution:

In the early days of the composting industry, there were a handful of notorious examples of facility failures triggered by a lack of composting knowledge on the part of the design firm.

Composting is a biological process, and everything – including the engineering – must support the biology.  Do not engage a consultant or designer without a number of successful ASP composting projects under his or her belt. 

There’s an ASP composting system for every budget

Upgrading to ASP processing needn’t be an expensive proposition.  In fact, at $2000-$10,000 a pile, installing fans and piping could be one of the most cost-effective decisions you’ll ever make for your composting operation.

Converting will also dramatically reduce the size of the facility.  McGill estimates its plants can process 10 times the volume of an outdoor windrow operation within the same size footprint.

The numbers for your facility may vary, of course, depending on factors like the specific aeration technology and monitoring system, level of process containment, etc.

But with that extra space, an owner can intake more material, add an anaerobic digestion unit at the head of the plant, install a small solar farm, or simply expand its perimeter buffers.

It’s hard to find a downside to ASP composting systems.  They’re penny wise and dollar smart, the best choice for operations ready to take on the challenge of today’s urban organics.

Composting done right is not one size fits all

Environmental footprints are as varied in size and weight as the people and entities who leave the impressions.  

Companies like McGill recycle compostables for some of the largest waste generators in the country.  So why do we support community-scale and backyard composting?  Because composting done right is not one size fits all.  No single composting option is right for all organic waste streams.

In an ideal world, every business, institution, and household would have a composting operation of some description on the property.  The resulting compost would be reused nearby – on site, local urban garden, public greenspace, etc.

But while some folks would do a stellar job of converting that waste into a beautiful soil amendment, others would not.  Just imagine the resulting mountain of nuisance complaints and serious public health issues.

There is no cookie-cutter for composting done right 

The next best thing seems to be our present system of allowing property owners and communities with the ability and inclination to compost to do so, trusting the management of the remainder to big, professional outfits like McGill.

It’s a system that matches the size and type of the waste stream to the capabilities of the processor.  

Everyone gets to wear shoes that fit while making their footsteps on Planet Earth just little bit lighter.

But it’s important for the developers of these facilities – from backyard to industrial – to match facility design and process to the waste stream and site location.

Without ruffling a single neighborhood feather, a suburban homestead sitting on a couple of acres might build a simple slat/pallet enclosure. Folks could throw up a ring of wire mesh in the corner of the property and compost there.

But the same household, composting in a more congested setting, could trigger an avalanche of community complaints about mice, flies, and smells.  Here, a fully-enclosed gizmo like a tumbler might make more sense.

An urban food waste collection service composting well beyond city limits may do just fine with an outdoor windrow operation.  But placing that facility on an urban farm, surrounded by homes and/or businesses, could be a mistake.

For an industrial-sized plant sited in a manufacturing park, full enclosure and high-rate systems are probably mandatory.  But at a far-off landfill, that same waste stream might be successfully processed using a well-managed windrow.

Numbers don’t guarantee a good fit

Most are aware of the problems associated with buying shoes and other wearables strictly by a number.

One manufacturer’s size 8 could mirror another’s size 12 measurements.  A size 10 boot might be fine in length, but chafe at the calf.

So it is impossible to use numbers like processing tonnages or acreage as sole determinants when wrestling with a composting system match-up.

A general location might look good on paper, but when the only available sites in the area are public relations and regulatory disasters waiting to happen, the fit is all wrong. 

Outdoor windrows are cheap.  But urban waste streams demand tighter environmental control and facilities that don’t require large swaths of expensive real estate.

Obviously, composting done right is not one size fits all or even one size fits most.

Contemplating a backyard composting effort?  Urban farm project?  Municipal facility?  Choose a site, design, and process that matches the waste stream.

Wetter waste streams (like food waste) require more sophisticated processes and tighter environmental control than dry feedstocks.  High-volume composters need indoor facilities and/or lots of acres with well-vegetated buffers to provide out of sight, out of mind assurance.

Composting done right is always a better fit for everyone than composting done wrong.

Home-compostable – bane or boon for the industry?

Compost certifications can be a bit of a muddle, especially for consumers.  Will this newest category help clear things up?

There is a new kid on the certifications block.  It’s called home-compostable” and has arrived in many parts of the world.  

Products based on this standard include next-gen bio-based films and resins manufactured with processes that will allow these types of plastics to degrade in the typical home composting environment.

The US has yet to develop a certification for this new compostables category.  However, the products themselves (carrying European and other certification logos) are available online and at some brick and mortar retailers.

And just this past April, scientists at a US-based lab announced a related breakthrough in its own project.  It’s a plastic that can completely disintegrate, even in the wild, without fouling soil, air, or water.  Cambridge just announced the development of a home-compostable resin, too.  

With the increasing availability of universally-compostable materials comes the promise of clarity for individuals and businesses hoping to divert more organics away from landfills and incinerators.

Should the industry care about home-compostable?

Let’s give this one a resounding yes.  If an item can compost at home, it should compost in most professionally-managed operations, too – big or small, municipal or commercial, indoor or outdoor, basic or advanced technology.

Home-compostable sets the stage for more successful municipal and commercial composting efforts when the most common bio-plastics can be composted almost anywhere by almost anyone.  No need for consumers to read the fine print as long as an item carries a big “compostable” label.

This paves the way for increased flows of food waste streams from non-composting households, restaurants, and other commercial and institutional entities – good news for composting’s existing infrastructure.

Thanks to science, objectives like universal compostability and disappearing plastic bags hover brightly on the horizon.

Even the US military is getting excited about the potential of this new breed of plastic.

But wait, there’s more

New plastics aren’t the only developments casting a warm glow over composting.

Advances in optical sorting technologies now facilitate the separation of waste streams into individual components.  Once widely adopted, these types of developments should increase capture rates of everything from plastics to fibers to organics.

The ability to utilize technology to separate wheat from chaff at all stages of resource recovery can positively impact everything from source separation to MRF management to anaerobic digestion.

Along the way, composting benefits, too, as the recipient of higher processing volumes and lower contamination of the organics stream. 

When some are starting to ban compostable plastics, the introduction of universally compostable resins is more than timely.

Emphasis on consumer-friendly labeling, alluring consumer incentives, and the modernization of the recycling/composting industries are keys to maximizing resource recovery, creating efficiencies, and fostering true circular economies for organics.

Throwing up one’s hands and abandoning the recycling of any material is no solution, especially when new products and technologies are waiting just around the corner.

Whatever happened to aiming for the best waste management option? 

If it’s easier to do, then it’s the thing to do.  If the job can be done faster by cutting corners, go for it.  If it’s the cheapest option, buy two.  Somewhere along the path of societal evolution, easiest-fastest-cheapest has become synonymous with best.  This linguistic transmogrification is so pervasive, society no longer takes notice of its shortsighted slide down a spiraling path toward all things inferior.

When did easiest-fastest-cheapest become synonyms for best? When did we stop aiming for the best waste management choices and settle for inferior? 

There are good, affordable options out there that can strengthen/support recycling mandates and result in better waste management systems.  But progress toward zero waste is s-l-o-w and too many communities are still stuck in their comfortable ruts.

Progressive leadership looks to the future, ever-steering its constituency toward that proverbial “brighter tomorrow.”  For waste management, that horizon does not include landfills or incinerators. But it does include high-rate industrial composting … if public and private facility owners aim for the best and not the cheapest.

What are the best options for biodegradable wastes, the best organics collection strategies, the best composting technologies, the best facility designs, the best uses for compost products – who asks these questions before plunging head first into a development project?

Or, if someone asks the questions, do they really mean what’s the cheapest technology, design, and collection strategy? 

As for the resulting compost product, is the real objective to put it to highest and best use or to get rid of the stuff as easy and as fast as possible?

‘Best use’ is hard to achieve with an inferior product

Stormwater management, erosion control, carbon sequestration, turfgrass management, landscaping – these rank among the best uses for compost products.

They represent markets that place high dollar value on stable, quality soil amendments with no odor, high organic matter content, macro and micro nutrients, and other characteristics linked to a high-performance product that can be safely used by anyone, anywhere, at any time.

Poor quality compost cannot meet this minimum standard.  For the most part, its sale and distribution is restricted to low-dollar markets like farming and landfill cover.

The catch here is that, when managing mixed organic wastes, it usually requires a combination of the best facility designs, composting technologies, and management protocols to produce a really good compost product.

To achieve top quality, keep product moving out the gate, and ensure the highest possible revenue stream, a facility owner must match those aspirations with a high-quality manufacturing process and competent management that includes a professional sales effort.

Shortsighted strategies won’t meet long-term goals

Many communities are waking up to the fact that their long-range plan needs to include a viable strategy for organic waste management that keeps biodegradable materials – especially, food waste – out of landfills and incinerators.

Composting certainly fits the bill, and it’s often possible to modify an existing yard waste windrow permit to include other organics.

But what happens a few years down the road when that one load of food waste per week turns into a load per day, and then two loads per day, and then 10 loads per day?

When the entire city is source-separating organics curbside, and the vast majority of those garbage trucks are headed for that crowded, outdoor windrow composting facility, what happens then? 

Historically, facility owners (public and private) can struggle through years of banned feedstocks, failed lab reports, public complaints, unsellable product, fines, and/or legal fees before finally facing the facts. Their antiquated composting system simply isn’t up to the challenge of today’s urban waste streams … and their bargain basement facility wasn’t such a bargain after all. 

Successful high-volume processing of urban streams that include highly putrescible materials and biodegradable plastics requires tight environmental control and a high-rate composting process. 

If a facility owner wants to process in the least amount of space, taking the least amount of time, using the most reliable, predictable process, then that owner is going to convert that lesser system to the best system for mixed urban organics.  A covered and/or encapsulated aerated static pile (ASP) system, preferably with computerized control/monitoring and biofiltration, meets those expectations.

But how much might that region or business have saved/earned by investing in an expandable, high-rate facility in the beginning?  Remember, we’re not just talking composting, but all the dollars saved associated with compost use, too.

While Nero fiddled, Rome burned

Fiddling about while the city buries itself under a mountain of garbage is not an example of good governance.  In the private sector, failing to invest in upgrades and new technologies sets a company up for obsolescence.

Both depict outcomes resulting from failure to act when the time is right.

Unlike even 10 or 15 years ago, when most people were clueless about the many benefits of organics recycling on a municipal/industrial scale, today’s taxpayers are aware of composting as a waste management strategy.

Large volume waste generators in the private sector have been using commercial composting services for decades for one reason only – it’s more cost-effective than landfills.  As a bonus, it also gives corporations green points to use in their marketing messages.

Is it right for governing boards to continue to expect taxpayers to pay more simply because those who made the decision failed to be proactive in their decision-making?

No single option will be right for every community.  But giving serious consideration to organics recycling is always the right thing to do.

Starting at the top and working down is a lot easier than trying to claw one’s way up from the bottom.  So, aim for the best solution first, even if it’s not the easiest, fastest, or cheapest option.  

Then, use easy-er, fast-er, cheap-er tweaks to mold that system into the perfect waste management approach, customized to meet the unique needs and expectations of each community or business. 

Yes, we can build a composting facility for you

Do you want to build a composting facility?  Are you —

  • A private waste management company hauling 35,000 tons or more of biodegradable waste annually and paying more than the U.S. average tipping fee to dispose of that waste at a landfill,  WTE facility, or incinerator?
  • An AD system operator wanting to maximize the market potential of a low-value digestate?
  • A landfill owner hoping to extend the life of the landfill or trying to devise a strategy to meet the growing demand for food waste composting?
  • The utility director of a municipality currently hauling compostable waste to a commercial landfill or incinerator with service contracts expiring within the next few years?
  • A food processor with food waste and other biodegradables like DAF sludge and packaging waste (broken pallets, dirty cardboard, etc.) at multiple plants within 100 miles of a central location?

If the answer to any of these questions is yes, building your own composting facility may offer cost and efficiency savings, as well as long-term pricing stability for the biodegradable fraction of any waste stream,  all while offering a real revenue opportunity from the sale of high-grade compost to plump up the bottom line.

We’re not talking about throwing some clay down in a cow pasture and calling it a composting operation. We’re discussing modern, advanced technology, high-rate facilities that can handle everything from yard waste to biosolids to food waste and biodegradable plastics with aplomb.

And if you’re currently paying high tipping fees or driving long miles to dispose of this material, owning your own composting plant may be just the ticket to price-hike independence and lower costs.

These indoor, industrial operations are weather independent, providing reliable, predictable throughput.  When coupled with a modern process and professional management, they will produce a high-grade compost product with real market value for high-end customers in the golf course, turfgrass, parks and rec, retail lawn and garden, and like industries.

One of the best things about modern, environmentally-secure composting operations is that they take up very little space compared to outdoor windrows.  Ten high-rate facilities can be built within the boundaries of one outdoor windrow operation with the same throughput.   

Because of their biofiltration systems, they can also be sited much closer to population centers than the old-fashioned variety.  Contained, encapsulated processing and aerated processing systems all but eliminate headaches like leachate, off-site odors, and failed tests as management issues. This high level of control also results in a very rapid degradation process, with primary processing completed in a matter of days.

When choosing a composting system vendor, look for a firm with deep experience and a string of financially and technically successful composting operations under its belt.  Companies like McGill (which both operates its own industrial facilities and designs facilities for others) offer a definite advantage over those without these credentials.

Decades of hands-on experience processing some of the most challenging organic waste from municipal, industrial, and agricultural streams will trump a design-only firm with no operating expertise.  

McGill’s design-build options also include operations management and product marketing.   Learn more about McGill’s DBO services here.

What is a composting facility package plant?

In the water/wastewater treatment and composting industries, a package plant typically refers to a small, prefabricated unit dropped on-site, ready to connect to the larger system.  A McGill composting facility package plant is different.

Since McGill doesn’t build small facilities, its “package” is actually a set of blueprints and specifications for an industrial composting plant pre-engineered to meet the specific environmental containment, throughput, and feedstock requirements of the owner.

Actual construction may include prefab and off-the-shelf components, but there is likely iron going up at the site and concrete to pour, too.

While the owner is still responsible for site-specific engineering,  all other aspects – structure, process, operating procedures, etc. — are provided with the package.  Initial crew training and start-up supervision is included, too.

Pre-engineered McGill facilities ensure efficient, economical operations because they are designed by folks who have been successfully building and running trouble-free, 100,000+ TPY commercial plants for nearly 30 years.      

Commercial vs. industrial composting:  are they the same? 

Commercial vs. industrial composting — no, they are not the same, though the terms may be used interchangeably on the web.  But one word has to do with the money trail and the type of organization that owns the facility.  The other is linked to operational scale and/or manufacturing approach. 

A government-owned operation is not commercial, but it could be industrial in scale. It could also be operated like a commercial facility with a similar structure and profitability goals. 

A privately-owned facility would be commercial but might not have any claim to industrial.  A small facility owned by a nonprofit may be neither.   Big, modern compost manufacturing plants may be both. 

What makes a composting operation commercial? 

A “commercial” facility infers ownership by an individual, partnership or corporation, with profits accruing to the benefit of the owners’/shareholders’ bank accounts.  “Commercial” doesn’t have anything to do with the processing method in use, facility design, throughput, technologies, or manufacturing systems. 

Composting operations owned by municipalities, counties, nonprofit organizations and the like are not commercial, because any profits realized go back into communal coffers to subsidize operations or fund other projects related to their respective missions. 

Government-owned plants are “public-sector” operations, while commercial facilities are “private-sector” operations.  Generally, nonprofits or not-for-profit entities are citizen groups and may also be referred to as non-governmental organizations (NGOs). Sometimes, an NGO may be established by individuals representing governments or agencies.  Like public-sector projects, composting facilities owned by NGOs could look very much like a commercial operation, complete with a revenue stream. 

How big is industrial scale? 

“Industrial” is a relative term, most often associated with factories and manufacturing.  In the 21st century, manufacturing infers mass production, big equipment, automation, systems, and uniformity.  Ergo, industrial scale infers a facility size that would require these things to improve efficiencies and revenues. 

When it comes to commercial and industrial composting, how big does the operation have to be to earn the designation of industrial scale?  How big is big? 

Again, it’s a relative term.  When doing research for this post, one of the findings was this article written in the mid-1990s that classified a 100-tons-per-year operation as industrial.   

Compared to the backyard compost pile, 100 tons is a big number.  But the average throughput of a composting operation in the U.S. is now approaching 4,500 tons per year.  There are 194 facilities processing more than 30,000 tons per year, some in the 100,000-plus category.   

It may be time to add one or two more zeros to the “industrial scale” definition of 1996. 

Still, size is only one indicator of an industrial facility.  But other adjectives that might be used to provide clarity are also quite subjective. 

Commercial vs. industrial composting — is “manufacturing” the key? 

The original definition of manufacturing (manu factum in Latin) literally translates to “made by hand.”  Today’s dictionaries typically describe manufacturing as making something manually or using machines.  But for most folks, the word conjures images of big buildings, lots of machinery, and cookie cutter output. 

Yet, no matter the variations in definition, one thing is clear — when applied to the manufacture of goods in the modern era, making something in an industrial setting requires production through a system that typically includes assembly lines, division of labor, a quality control program, and a sales network to move products out into the marketplace. 

Potato, Potahto 

Does it really matter whether a composting facility is commercial or not?  Industrial or not? 

The important thing is for composting operations of every description to make good compost.  How they do it or where the money goes is secondary and may not even be on a customer’s radar. 

A “commercial” facility may still imply private-sector ownership, but if public-sector owners are serious about their responsibilities to taxpayers, they’ll design, operate, and generate revenue from compost sales like the privately-owned. 

Protecting the integrity of the process and quality of the finished compost matters.  Hiring experienced, qualified compost facility operators matters.  Practicing preemption when it comes to the environment and preventing deterioration of the quality of life for the host community matters.  Providing stellar service to both intake and compost sales customers matters. 

These are the indicators of a successful composting operation, whether commercial or not, industrial scale or not.  At the end of the day, professional and profitable are among the most important descriptors for any composting facility. 

LEARN MORE: 

Making sense of research data

Evaluating organic waste management options and cost comparisons

When personal expertise is lacking, people place their trust in experts to facilitate decisions about everything from home additions to medical care.  Governing boards are no different.  They rely on the knowledge of utility directors, staff engineers, and consultants to help them make informed decisions.

But when presented with an avalanche of numbers – from scientific data to cost and operating projections – how do members of city councils and county commissions know if the information contained in that mountain of reports is accurate and unbiased?  How do they know they’re comparing apples to apples and not apples to oranges?

Placing value on studies specific to waste management can be complex.  One report might compare landfilling, incineration, and anaerobic digestion, but leave composting out of the mix.  Another may include composting, but base assumptions on an antiquated window system and not a modern, high-rate technology.  Research could unearth reports about a costly public project but never discover a more efficient, cost-effective commercial system.

This is not to suggest such errors or omissions are intentional.  Sometimes, it’s simply a case of “you don’t know what you don’t know.”  But when combined with the fact that detailed financial or operational data from private-sector owners is rarely made available in public spaces, one begins to understand the difficulty in obtaining good data on which to base conclusions and recommendations when doing composting cost comparisons.

The takeaway?  Assume all research is flawed in some way.  No one knows everything there is to know about every subject.  But there are a handful of questions that members of city councils and town boards can ask to help clarify reported numbers, level the playing field, and present a more accurate picture of construction and operational realities.

Who paid for the research?

Perhaps the most significant influence on any research project is the entity that foots the bill.  Even university research is funded by someone … and it may not be the university.  Non-profits may fund research, but they rely on the support of donors.  Government agencies can be funders, but governments are run by politicians.  When the private sector funds studies, the results may never see the light of day if unfavorable to the funding entity.  Student work may not be funded, but it’s still student work.

Was the research scientifically sound?

Some “research” may not be new research at all, but assumptions or conclusions based on a literature review that includes outdated or invalid findings.  Investigations may have been conducted in a manner that does not reflect “good science,” including a lack of statistically-representative sampling.  Some findings are more opinion poll than science.  But when sifting through millions of scientific papers for data, researchers won’t always pick up on these types of flaws.

Also know statistics can be presented in a manner that makes differences look more (or less) important than they really are.  (See an example in this SlideShare title:  Apples and oranges: comparing waste management technologies)

How old is the research data?

Unfortunately, it’s all too common to discover a case built on multiple levels of citations that eventually trickle down to data or conclusions that may not reflect present day realities.  Knowing the date and technological sophistication of the original study will help decision-makers evaluate the value/validity of the conclusions and recommendations included in the consultant’s report.

Don’t accept a current date on a citation at face value.  Follow the citation trail to the date and circumstances of the original research.

Is data based on full-scale operations using current technologies?

Was the data based on bench scale, pilot scale, field scale, or full scale?  Conclusions reached during early stages of product or system development can fail to “scale up” successfully.   Investigations based on dinosaur technologies of 20 or 30 years ago exclude advancements and enhancements made in recent years, distorting findings.

For composting specifically, ensure that systems and technologies are apples-to-apples comparisons using the most current data available.  If evaluating high-rate systems, include successful private-sector facilities, too, not just municipal.   Net expense and revenue values per ton processed can vary widely between different types of operations.

Using old data and processing systems for dollar comparisons could greatly skew conclusions when comparing composting to other waste management technologies.

Sometimes, imperfect is the only data available for composting cost comparisons

When conducting research in a field like composting, where meaningful research is scant, at best, the imperfect may be all there is.  Knowing and accepting this reality, proactively seeking out the most accurate information, and evaluating results based on a variety of studies and viewpoints can only help decision-makers make better choices for their respective communities.

Read the article:  Valuing composting as an infrastructure investment

Industrial, high-rate composting:  exploiting the power of microbes

Thirty years ago, beyond the entry sign announcing the location of a composting operation, it wasn’t unusual to see a former cow pasture crowded with long rows of rotting yard waste.

Start-up for these primitive facilities was (and still is) relatively cheap.  A windrow operation is viewed as simple and attracts owners whose primary goal is to get a facility up and running without investing much in capital.

However, in all but the most arid climates, the Great Outdoors is not that great for the microbes responsible for composting’s biodegradation.  Aerobic microbes — the stars of every bona fide composting operation — will only reach peak performance levels if they are protected from the elements, provided with an ample food supply and a bit of water, and live in an environment equivalent to a microbial Goldilocks Zone.

Bring all of these conditions together in one place, and composting doesn’t just happen.  It goes gangbusters.

Today’s industrial composting plants and advanced biodegradation systems are designed to do just that, because the realities of high-volume organics recycling often demand more than the typical windrow can provide.

Science-based recycling systems — exploiting the power of microbes

When serving metropolitan areas, composting operations can be expected to recycle everything from fecal-laden yard waste to industrial by-products — in high volumes. These facilities intake and process hundreds of tons each day.  The larger operations may be processing 100,000 tons or more per year.

Odors emanating from some of these feedstocks can be unpleasant.  The materials can be very wet.  A few will carry chemical residues that require an advanced degradation technology to render them safe for reuse as ingredients in soil amendments.

That’s why more modern plants, those tasked with managing multiple types of organics from large geographic regions, are indoor operations.  Some may still turn under that roof, but others have kicked it up a notch by employing more advanced systems (i.e., aerated static pile or ASP) instead of turning.

While a windrow tends to plod along, controlled aeration accelerates composting, turning stodgy microbes into sleek degradation athletes.  With high stamina and a voracious appetite for all things organic, these Olympians of the microscopic world bring speed, reliability and high performance to an otherwise lackadaisical process.

The industry’s transition from windrow to ASP turbocharged composting, exploiting the power of microbes and giving it the efficiency and predictability required to successfully compete with landfills and incinerators.  But this metamorphosis did not result from genetic manipulation, chemical additives or fairy dust — it was simple biology.

That’s it.  Not engineering.  Not artistry.  Just biology, specifically, exploiting the power of microbes.

Prior to some notable research by scientists beginning in the 1950s, folks may have known how to keep a compost pile chugging, but not why their management efforts worked.  But once researchers figured out the why, they were able to control the process by giving aerobic microbes exactly what they needed to survive and thrive (air, water, food, temperature) in the right amounts and within ideal ranges.

They discovered composting’s Goldilocks Zone.

By the 1990s, this academic exercise had captured the eye of the commercial sector.  With some tweaking to improve efficiency and profitability at scale, a robust, predictable process emerged, one with the ability to cost-effectively recycle high volumes of organics.

But back to those microbes…

After many trials and several errors, industrial composting moved into the waste management mainstream.   But to make biology work as the power behind the progress, both designers and facility operators had to grasp, embrace and deploy a few scientific principles.

At the core was a rudimentary understanding of the two broad categories of biodegradation processes – aerobic and anaerobic.  Each identifier reflects the environment in which the microbes live.

Aerobic organisms require air and water, but like people, they cannot breathe under water.  Conversely, anaerobic microbes are like fish – they’ll die when exposed to air.

Anaerobes live and thrive in much wetter conditions than can be tolerated by aerobes. Both prefer a moderate temperature zone.  Anaerobes will die off at around 150 degrees Fahrenheit (F) or 65.6 degrees Celsius (C).  While aerobes can tolerate more extreme temperatures, the most active phase of aerobic composting takes place between 55 and 155 degrees F (12.8 to 68 C), with a preferred range of about 122-140 degrees F (50 to 60 C).

Anaerobic fermentation generates methane, which can be a good thing if captured and used for heating, cooking and generating electricity.  If not, then it’s a bad thing, a potent greenhouse gas.  When anaerobes are at work, certain compounds are created during intermediate degradation stages that result in unpleasant odors.  That is why some wet, decaying materials carry an offensive stench — the rotting organic matter has “gone anaerobic.”

But an aerobic process neutralizes odors by creating drier conditions, killing odor-causing anaerobes.  Methane is not generated during a well-managed aerobic composting process, and the resulting carbon dioxide emissions are considered carbon-neutral since the gas generation volume is the same as if the materials degraded naturally.

Beneficial bacteria and fungi are among the aerobic microbes that make compost “happen.”  About 2,000 species of bacteria and 50 species of fungi are ably aided in their degradation efforts by a zoo of macro-organisms like beetles and worms.  However, aerobes are the worker bees of the compost pile.  They break down organic matter at the chemical level as opposed to the physical rending of the macros.

Feeding on organic waste, aerobes power the engine that drives moisture from the composting mass, degrades pollutants, and eliminates odors.  The enzymatic action associated with aerobic digestion breaks molecular bonds, releasing by-products (heat, water, carbon dioxide) in the form of steam.  Once these microbes have consumed all available food, they die fat and happy, their microscopic bodies becoming part of the residual mass.

In a controlled composting process, a temperature drop signals a decline in food supplies and a correlating reduction in microbial populations.  Degradation slows, but still continues at the lower temperatures associated with compost curing.

If left to time and nature, organic matter will continue its disintegration until nothing remains.  But long before that happens, biodegradation enters a phase where the residual is relatively stable, while still microbiologically active and chock-full of both macro and micronutrients.  With its soil-like aroma and appearance, the material is pleasant and easy to use – a critical requirement for any product intended for widespread general use — and really, really good for rebuilding depleted topsoil.

This stuff, of course, is compost.

Microbes just keep going and going and…

When talking microbes, conversion of waste to valuable product is only half the job.  Once that compost has been added to soil, the little critters take on even more tasks:

  • DEGRADATION OF POLLUTANTS – microbes break down synthetic compounds to neutralize the impact of things like petroleum products and fertilizers/chemicals that can negatively impact both soil and runoff quality.
  • IMPROVE NUTRIENT UPTAKE – microbes convert nutrients to plant-available form, making more food available to plants and reducing the need for synthetics.
  • IMPROVE DISEASE RESISTANCE — microbial activity is responsible for the plant disease suppression associated with compost use.

The influence of science on facility design

The biggest problem with outdoor operations is not weather, per se, but the fact that weather cannot be controlled.

If a composting mass needs moisture, rainfall can be a welcome addition.  While it’s common for the sides of a compost pile to “crust,” discouraging rain infiltration, piles can be flattened and then concaved on top to capture rainfall for slow infiltration over time.  In this regard, rainfall can be a compost manufacturer’s friend.

But excess rainwater rolling down the crusted sides of a pile will settle into pools of “black liquor” (a.k.a. leachate) at the base.  Leachate and associated runoff contaminate ground and surface waters, attract flies and harbor unpleasant odors.  If the pile gets too wet too soon, pathogens rebloom.  When composting outdoors, a heavy rainfall can set the stage for nuisance complaints and regulatory intervention.

Conversely, maintaining acceptable processing conditions outdoors during dry spells requires sprinkler systems or a hose brigade if the microbes and the process are to be saved.

Add complications like high winds and ice storms to the mix, and the operation of an outdoor facility becomes more about battling Mother Nature than recycling organics.

Having to reprocess ruined piles and windrows adds cost and retards throughput. When hundreds of tons of waste arrive at the gate each day, a stuttering throughput rate can cause massive pile ups that compound and exacerbate the weaknesses of outdoor facilities.

Exploiting the power of microbes means protecting the creatures from the vagaries of weather is a top priority for modern facility designers.  Solutions can range from a shed roof to encapsulation to full facility enclosure.  Each rung on the containment ladder offers an elevated level of environmental control and protection, as well as fewer operational complications.

On that list are the elimination of materials handling woes related to weather delays and the ability to capture inside air and processing off-gases for biofiltration.  Indoor facilities can also make a composting operation more palatable to the locals by providing visual camouflage and sound buffering.

Making biology work for day-to-day operations

Putting a roof over a composting operation may remove many headaches from the manager’s plate, but design is only as effective as the people running the place.  Any composting facility — from the most basic to the most sophisticated — can still run into trouble if mismanaged.

Exploiting the power of microbes requires a multi-faceted strategy.

Feedstocks like food waste and biosolids can be wet and odor-laden when they arrive at a composting facility.  One of the top priorities for modern composting operations is to get these types of materials blended with dry amendment and aerated as soon as possible to kill off anaerobes and encourage the proliferation of aerobes.

But if the blend isn’t right, a batch can be doomed before the admixture ever hits the composting pad or aeration floor.  Wet or dry pockets impact microbial movement throughout the composting mass.  An irregular texture means patchy distribution of target compounds and uneven exposure to the microbes.  Pockets of untouched raw waste can survive an otherwise successful process, leading to regeneration of odors and reblooming of pathogens.

Particle size needs to be consistent to achieve an even degradation rate for all blend ingredients.  Material placed on the composting pad should not be compacted.  Aeration pipes must be free of debris.  Windrows may need more turnings than required by regulations to keep the process humming.

Many items on the list of best management practices (BMPs) are common to all composting operations, from backyard to industrial.  Many items on the DO list relate to the creation and maintenance of an ideal environment for the microbes responsible for biodegradation.  The DON’Ts focus on discouraging of the kind of microbes that cause and perpetuate odors.

But no matter the design or process, people are ultimately responsible for making the science work as it should, keeping those all-important “bugs” happy and ensuring a trouble-free operation.

LEARN MORE