It's a Natural

By Denise K. DeLuca

Turning organic wastes into soil amendments emulates natural cycles and solves problems created by current waste management and agricultural practices. We need to consider how these operations are currently handled and the consequences that flow from business as usual. Perhaps the waste manager can create new solutions that profitably connect with the needs of the farmer.

My article, "Sustainable Waste Management: A New Goal for the New Millennium" (MSW Management, September/October 2000), described the tremendous progress we have made in waste management since the days of the town dump. It also illustrated the need for us to work together to achieve the next goal of waste management: sustainability. I'm sure many readers had the same thought as I: "Yes, but… " Goals can be big, lofty, and somewhat esoteric. Difficult to get a handle on, more difficult to put on paper, and perhaps seemingly impossible to put on the ground.

What does a logical thinker do when faced with a difficult problem? Break it down into smaller and smaller components until they are a workable size. When considering how to implement the goal of sustainability, it's important to consider the individual components of the MSW stream, which is typically about 60% compostable, 30% recyclable, and 10% other.

The "10% other" category represents not only the smallest fraction of the wastestream, but also the most diffuse and thus the most difficult to get a handle on. This category contains things like disposable razors, burned-out coffeemakers, broken toys, flashlight batteries, and all those containers that don't seem to belong in any of your recycling bins. It also includes all our nasty and usually unnecessary household hazardous wastes. Embarrassingly, we have been convinced that we should, for example, spray or squirt or pour or flush environmentally persistent poisons down our toilet so that we can enjoy a darn-near germ-free toilet bowl … for about five minutes. The germs, of course, are quickly replenished; nature, however, is damaged forever. If consumers demanded it, the items in the "10% other" category would be fixable, be made of easily recyclable materials (or easily disassembled into recyclable components), not be produced in a "disposable" form, or simply be banned. In other words, with appropriate implementation of the three R's, (reduce, reuse, and recycle) the "10% other" category could all but disappear.

The 30% of our wastestream that is recyclable has historically been the major focus of our alternative waste management efforts. We've made tremendous inroads into recycling, but we still have a long way to go. Work in the recycling arena seems to follow the "two steps forward, one step back" routine. For various reasons, the recyclables market is ridiculously volatile, thus rendering cost/benefits projections almost meaningless and investments risky. The whims of our marketplace also result in frequent changes in products and packaging, further hindering the ability to plan for and manage wastes of this sort. With the cooperation and active participation of industry and consumers, and with a little motivation from our government, however, reuse and/or recycling could become the most efficient, practical, and cost-effective solution for all our nondegradable products and packages. So again, with appropriate implementation of the three R's, the items in the "30% recyclable" fraction might no longer even be considered a part of the wastestream.

The Focus on Organics

That still leaves us with 60%–more than half–of the wastestream. This category includes foodwastes of all forms and at all stages, other vegetative wastes, and various paper products that are not readily recyclable. This 60% is often referred to as the "compostable fraction." It could also be called the organic fraction, greenwaste (referring to the vegetative source of the materials, not a political movement), or biodegradable waste, or perhaps it is covered by the "wet wastes" category. Whatever you call it, it is this 60% on which I believe we need to focus our waste management efforts.

The first of the three R's, reduction, is applicable to some organic wastes, but generally not foodwastes. Although many of us could use a little reduction here, we all need to eat, and the number of hungry people on earth continues to rise. The second of the three R's, direct reuse of this material, is also not widely applicable, though some clean foodwastes can be fed to animals. This material can, however, be recycled. In fact, recycling the organic fraction of the wastestream fits most easily into the concept of sustainable waste management. It is already biochemically natural and renewable–we simply need to return it from whence it came. As the title of this article implies, it's a natural.

Though many of us in our ultrabusy, high-tech lives might feel pretty removed from nature, most of us still at least occasionally peel oranges, crack eggshells, or grind coffee beans. Every day we eat and drink and generate foodwaste. The problem is, although our foodwastes are still in a (reasonably) natural state, we throw them into the garbage can along with our dirty plastic wrap, spent pens, and all those "10% other" items. It all goes to waste–literally. That is what happens in your own home. Now think of what happens at grocery stores, restaurants, and cafeterias.

Tons and tons and tons of clean organic material–more than half of our total MSW wastestream–are carted off to the landfill destined to become someone's leachate or methane management headache (perhaps yours!). And since organic wastes are wet, they're also expensive to haul and weigh-in heavy at the tip scales. For these reasons alone, it appears to make sense to find an alternative to hauling and landfilling this material. But there is another–perhaps more compelling–perspective.

Stealing From the Soil

Remember the Dust Bowl? Those devastating losses of soil taught us that we need to respect the land and take care of the soil that feeds us. Well, sort of. We've learned many lessons since then and implemented several of them, but still we treat the soil as if it were simply something to keep in place. We seem to think that as long as it doesn't flow or blow away, the soil will serve us forever. But something is missing in this logic.

Remember the concept of conservation of mass? This fundamental law states that Inputs — Outputs = Change in Storage. Thus, even if you know nothing of the biology or chemistry of soil, you can understand that if you grow a crop in the soil every year, and every year you remove the most nutritious part of that crop, a net loss to the soil must result. Applications of inorganic fertilizers abate this loss to some degree, but still you end up removing far more than just the nitrogen-phosphorous-potassium that is applied.

What is the loss from storage? The complete answer lies within the complexities of soil biology and chemistry, but the simple answer is organic matter–organic matter in all its various biochemical forms and states. It includes everything from multitudes of soil microbial communities, to decomposing cellulose and protein and carbohydrate, to aged black humus. It's what is needed to sustain the soil's ability to sustain plants. It is what gives soil its health and its structure. So if you lose more organic matter than you return every year, the organic-matter content of the soil will be slowly depleted, and with it the soil's natural ability to sustain plant growth.

If organic matter is so important to the soil, how can we deplete it and yet still grow crops year after year? It's simply because our beautiful agricultural soils are deep and dark and rich in organic matter and as such can be, and have been, mined of these materials for many years. This mining is partially overcome by incorporation of crop residues and occasional applications of manure, but obviously our soils can't be exploited as such forever. The soil organic-matter pool is continually reduced, but in the United States we have yet to hit rock bottom (so to speak), so we really haven't worried about it. We have simply increased our applications of, and reliance on, external inputs of inorganic fertilizers, soil conditioners, pesticides, and water. In many parts of the world, however, they have hit rock bottom, and starvation has been the result. This problem is potentially far worse than the Dust Bowl because the soil that remains will hardly be worth our efforts to save.

Energy Sink

Another basic concept we are all familiar with is conservation of energy. Again, we have the equation Inputs — Outputs = Change in Storage, and again we find that our current practices lead to a net loss. Perhaps our effort to turn corn into ethanol fuel best illustrates the problem here. Corn crops in the US are beautiful, but they are grown with the help of enormous quantities of, among other things, inorganic fertilizers–primarily nitrogen. Unfortunately, it takes tremendous amounts of energy to produce inorganic nitrogen fertilizer. The result? If you run the numbers, the conservation of energy equation tells you that, using standard agricultural practices, more energy is required to produce ethanol from corn than is contained in the ethanol that is produced. In other words, the process yields a net loss of energy. This energy balance yields a net gain simply by eliminating the use of inorganic nitrogen fertilizers.

All this talk of organic matter doesn't even take into account the inherent problems with burning fossil fuels to produce inorganic fertilizers or applying increasing levels of pesticides to make up for the soil's inability to fight pathogens in its weakened state. Air and water pollution, dependence on foreign energy supplies, mining, environmentally persistent poisons, increasing dependence on and resistance to pesticides … the list goes on.

The Connection

Now let's look at how our food production and waste management systems fit together. We burn immense amounts of fuels to produce inorganic fertilizers to produce crops. We harvest and process the crops into food products that eventually generate "waste" materials. We then burn more fossil fuels to haul and bury these waste materials in landfills. Later, these "waste" materials generate leachate and methane causing more pollution, or at least requiring more management efforts. Sound sustainable to you? Of course not. But "Mother" knows best. Mother Nature has set things up so that one process feeds into another in endless, mutually beneficial cycles. The remains and residues of plants and animals are processed to help produce more plants and animals. Nothing wasted, nothing lost. Pretty simple. All we have to do is emulate Mother Nature.

Perhaps some numbers will illustrate how things could work. If we assume that Americans generate 118 million tons of MSW each year, and 60% of it falls into the "organic waste" category, then we would have about 71 million tons of organic raw material to work with annually. If just half of the nitrogen (N) contained in this raw material (3% N, dry weight) were recovered, we could generate 320,000 tons of organic nitrogen fertilizer each year. This is enough nitrogen to fertilize more than 5 million ac. of corn (at a rate of 120 lb. N per acre). Not only does the corn receive the nitrogen and other nutrients it needs, but the soil's organic matter pool is replenished too. In this process, 71 million tons of waste are diverted from the landfill and made into fertilizer instead of being made into methane and leachate. But those are not the only benefits we would realize. Recall the energy balance? Fertilizing 5 million ac. of corn with an inorganic source of nitrogen requires energy equivalent to more than 135 million gal. of diesel fuel (this includes production, delivery, and application of the inorganic N fertilizer). Using an organic nitrogen fertilizer (such as compost), requires roughly one-third of that amount of energy, for a net energy savings equivalent to 85 million gal. of diesel fuel each year.

Why Not?

Recycling organic wastes certainly appears to make sense; or at least it doesn't make sense when we don't. So why aren't we doing it? How can a set of so obviously illogical systems continue to function? The answers to these questions are complex and multifaceted and lie within the intertwined networks of our political, economic, agricultural, and cultural systems. Perhaps we have come to value convenience and profit over common sense and common good. Perhaps the powers that be gain tremendously from our intensive dependence on fossil fuels and chemicals and thus have a vested interest in maintaining current infrastructures and wasteful habits. Or perhaps it is because as we have changed over time–some would say progressed–we have all too often realized gains without recognizing the simultaneous losses; and now it seems too hard to "go back."

As civilizations progress they become more specialized, but as specialization develops, disconnects develop too. For example, in the days of yore, the local farmer would haul his produce and meat to market, then haul the townfolk's food residues home to feed his pigs. The manure from the pigs would be used to fertilize the soil used to grow the produce that would later be brought to market. There was a set of connections, an interdependence, a natural cycling of resources with mutual benefits.

Now, the farmer is a corporation that specializes only in pigs, or wheat, or whatever. To be competitive, corporations must strive for total control of their inputs and outputs, thus both plants and animals are fed scientifically prepared rations of nutrients manufactured by another corporation. The farmer no longer comes to town, and the townfolk have their garbage picked up and hauled to a perhaps distant landfill. The vegetable farmer no longer has pigs to feed, and the pig farmer no longer has land upon which to spread manure. Specialization has led to many advances and conveniences but has simultaneously led to disconnects, and the natural cycling of our organic resources no longer occurs.

The Key: Cost and Convenience

Now that we realize the problem, why don't we "go back"? Again the answer, like the concept of sustainability itself, is complex and multifaceted. But the answer here might well be a simple matter of cost and convenience. We must always keep in mind that, regardless of social and environmental issues, no process can be considered sustainable in the US unless it is both cost-effective and convenient. When considering the management and subsequent use of the organic fraction of our wastestream, we must consider the issues of cost and convenience for both the waste manager and the farmer.

Let's look at cost and convenience from the farmer's perspective first. Given the choice of hauling and applying loads and loads of manure, compost, or other organic amendment, or instead applying concentrated inorganic fertilizers and soil conditioners, the decision is usually easy. Manure or compost spreading requires more labor, might be difficult to manage and, in the case of manure, might be rather unpleasant to deal with on a hot, humid summer afternoon. In addition, you'll have to figure out where to get this material, when and how much to apply, and how much it's all going to cost. If there is a cost savings or other economic benefit to be had, it isn't obvious. By comparison you're already set up to use the inorganic fertilizers and soil conditioners, it takes a minimum of labor, and the ag-chem rep tells you when, where, and just how much to apply. You know how much it's going to cost and have a pretty good idea of the economic benefit of the applications. It's simply easier to stick with what you know and what everybody else is doing. Anyway, it seems the soil will hold up for the foreseeable future, and you can always apply more chemicals to make up for any problems that might occur. And with today's tight profit margins, you certainly don't want to risk trying anything new.

Now let's look at cost and convenience from the waste manager's perspective. Given the choice of devising a new set of systems for collecting and processing organic wastes separately from your other recyclables and mixed wastes, or instead sticking with the status quo landfilling procedure, the decision is usually easy. Collecting separated wastestreams might require more labor, the materials might be contaminated, and–in the case of organic wastes–collection and processing might be rather unpleasant on a hot, humid summer afternoon. In addition, you'll have to figure out how and where to collect this material, how and where to process it, and how much it's all going to cost. If there is a cost savings or other economic benefit to be had, it isn't obvious. By comparison, you're already set up for hauling almost everything to the landfill, with some recycling done on the side. It takes a minimum of labor, and there are spreadsheets available to help you optimize your systems. You know how much it's going to cost and have a pretty good idea of the tipping fees you'll have to work with. You've come to the same conclusion as the farmer: it's simply easier to stick with what you know and what everybody else is doing. Anyway, you feel that you have to assume the worst when it comes to cooperation from the general public, and that the waste management alternatives you have heard or read about are probably too expensive, too untried, or just too "out there." And with today's tight budgets, you certainly don't want to risk trying anything new. Besides, what would you do with the organic fertilizers that you produce?

It is clear that there are two sides to this problem–that of the food producer and that of the waste manager–and thus a two-sided solution is in order. We need to build the foundations on both sides of the bridge, then bridge the gap. We need to use more organic (rather than inorganic) fertilizers and we need to use (rather than landfill) more organic wastes. The food producer needs well-understood, easy-to-use, and affordable fertilizers. If organic fertilizers become as or more convenient and cost-effective than inorganic fertilizers, they will become the preferred, and sustainable, choice for the food producer. The waste manager needs well-understood, easy-to-use, and affordable organic-waste processing systems. If organic waste processing becomes as or more convenient and cost-effective than landfilling, it will become the preferred, and sustainable, choice for the waste manager. At that point, it will be mutually beneficial for the food producer and the waste manager to reconnect, and once again we will have a natural cycling of resources.

What We Can Do

It's up to waste managers to find alternative technologies for collecting and processing organic wastes into organic fertilizers. Not an easy task perhaps, but you can begin right now by learning everything you can about the various options available for managing organic wastes. Currently the best options available are composting, anaerobic digestion, feeding animals, or various combinations of the three. You can read more about these and other new technologies on the Internet. The Internet is also a great place to find contacts and ask questions.

Composting is probably the most widely used method for processing the organic fraction of MSW. Composting technologies employ equipment ranging from pitchforks and piles to high-tech, computer-controlled composting vessels. Many municipalities have found that supporting home composting programs or running a centralized composting program for yardwastes is a cost-effective means for handling these wastestreams. Several municipalities compost as much of the organic portion of their MSW as possible by using one of several in-vessel composting technologies that have become available. This type of composting, combined with an active recycling program, can be used to divert more than 80% of the wastestream from the landfill.

Anaerobic digestion is a process used to produce methane along with a fibrous soil conditioner and nutrient-rich liquid fertilizer. Anaerobic digestion is similar to the process that occurs in a landfill, but as a controlled process, the resultant methane and liquid are desirable products. Anaerobic digestion is growing in popularity, particularly in Europe. This technology can also be combined with recycling and composting to achieve very high levels of diversion.

Feeding foodwastes to animals is, of course, an old "technology." But as discussed earlier in this article, it has been largely discontinued as a result of the specialization or industrialization of our agricultural systems. Clean food residuals, however, can still be fed to animals with beneficial results. This method simply requires connecting the right waste generators with the right food producers.

Once you understand your options, consider tackling your bigger or cleaner organic wastestreams first: yardwastes, grocery stores, restaurants, cafeterias, and food processors. Ask yourself and your waste generators if there are easy or inexpensive ways to keep the organic wastes separate from the rest of the wastestream. Work with your waste generators. Work with the equipment manufacturers. Work with local businesses and universities. Work with the departments in your city, county, and state that handle environmental protection and agriculture. Seek connections, explore mutual benefits, develop interdependence. With all of our cooperation and creativity, we can achieve sustainable management of our organic wastes. It's a natural.

Denise K. DeLuca, P.E., is the principal of Land & Water Consulting Inc. in Missoula, MT.