Revised February 27, 2017
When prehistoric humans gathered together in villages, they soon decided they didn’t want to keep all their trash in the village with them.
That decision marks the birth of the discipline of waste management.
People have probably always preferred to live in clean conditions. They have probably also preferred to clean their homes with the least possible effort.
Excavations of the earliest homes with clay floors reveal one way residents dealt with litter. They simply covered it from time to time with fresh clay.
Covering litter this way would gradually raise the elevation of their floor. The greater the population density and the more waste people generated, the less well this method worked.
At the dawn of civilization, villages were small and scattered. Land was abundant. People took the simplest solution to household waste management: find a bit of land not useful for anything else and dump all their refuse there. Most waste in early human history comprised various organic wastes (including human excrement) plus ash from fires, wood, and bones.
Archeologists studying ancient rubbish dumps find very little broken tools and pottery. People in early civilizations must have repaired and reused as much as possible. They may have also composted at least some organic waste.
Ancient and medieval solid waste disposal
Ancient Roman latrine
People on Crete in about 1500 BC put their rubbish in large pits and covered it with dirt.
The earliest laws we have concerning garbage dumps comes from Athens, Greece in about 500 BC. They mandated dumping trash at least a mile out of town. And explicitly not in the streets.
In AD 200, Rome instituted the first documented sanitation force. It employed teams of two men to pick up trash from the street. They threw it into a wagon, and took it away. “Away” in this case may have been a dump. Or perhaps they simply emptied the wagon into the Tiber somewhere downstream.
Similar practices continued in medieval Europe.
History records numerous laws of either a kingdom or city to deal with household waste management. As early as 1297, English towns attempted to require householders to clear the refuse from the front of the house.
As cities grew, they, like ancient Rome, designated people to be responsible for collecting waste and taking it out of town. Collecting waste included raking excrement out of streets and alleys.
The French failed to follow Athens’ wisdom in keeping the dump so far from the gates. During the time of the Hundred Years War, enemy soldiers could climb the massive garbage piles to storm the walls.
Early dumps were very unhealthy, but no one yet understood what caused diseases. They attracted rats, mice, and all kinds of birds. Among other diseases, the vermin caused outbreaks of plague.
Design of the modern landfill
Diagram of a landfill
What we call a small town is likely to be larger than many ancient cities. Since the beginning of the Industrial Revolution, we must dispose of not only household wastes, but industrial wastes as well.
Today our most pressing disposal needs are no longer ash from everyone’s cooking fires, etc. and manure from all the horses that supplied transportation.
\We have replaced them with new kinds of hazardous wastes.
Americans generate an average of 4.6 pounds of trash per person per day. That’s almost twice as much as most other major industrialized countries and three times as much as we generated in 1960. It adds up to 251 million tons every year.
We recycle or compost about a third of it and burn about an eighth of it, but we send more than half of it to landfills. Landfills use heavy machinery to compact the waste. That makes it take less room in the dump. It also cuts down on foul odors and gives less encouragement to vermin.
A landfill isolates trash from the surrounding air, earth, and bodies of water. It does so in part by isolating it from rainfall. A landfill must have a liner. If it has a clay liner, it’s called a sanitary landfill. If it has a synthetic plastic liner, it’s called a municipal solid waste landfill. At the end of every day, other machines covere the day’s accumulation of garbage with dirt.
In principle, then, a landfill takes care of the problems of odor, vermin, and pollution of streams. Total waste management problem solved?
Problems with modern landfills
Waste transfer station. Next stop, a distant landfill
Not quite. A landfill can’t go just anywhere.
Siting a landfill requires an environmental impact statement. Not all land is geologically suitable for landfill use. It can’t be in a flood plain or wetlands or near an earthquake fault, for example.
Geologically suitable does not mean politically acceptable. Landfills lower the value of surrounding property.
Any proposed landfill will have to overcome opposition from people who either oppose all landfills, or just those close enough to affect their living standards.
The liner solves the problem of separating the trash from the environment at the surface, but it causes another problem. It’s not possible to completely isolate the trash from rainwater. Water percolates through the trash and leaches out the various chemicals combined there.
This leachate collects at the bottom of the liner. If it remains, it will eventually find its way through the liner. And from there into groundwater. So a landfill must have a leachate collection system.
Because of the compaction and the daily dirt cover, organic matter will not decay rapidly. Eventually, isolated from air, it will decay anaerobically. Anaerobic digestion produces methane and small amounts of ammonia and hydrogen sulfide.
Besides being a potent greenhouse gas, methane can explode. In principle, landfill gas can be an energy source. Electric generating plants can use landfill gas. Landfill gas can be used in place of natural gas. In practice, though, most landfills simply burn it. The byproducts of burning have a less serious environmental impact than simply letting it accumulate in the landfill or escape into the atmosphere.
Eventually, the landfill will fill up. It can be put to other use, but only after about 30 years of monitoring. That’s 30 years during which the landfill incurs expenses but produces no income from tipping fees.
The looming problems of landfills
Trash and recycling truck
I don’t seriously believe the human race is capable of solving one big problem without creating another one down the road.
The speed at which the landfill stopped being a solution and started being a problem provides ample evidence.
Some jurisdictions have begun to ban plastic shopping bags, Styrofoam, and other light-weight, high-volume wastes.
It’s a short-sighted policy that already has unintended consequences.
If stores can’t use plastic shopping bags, they don’t have to collect them for recycling. What are customers supposed to do with bread bags and such with no place to take them?
Electronic waste likewise doesn’t belong in landfills. For one thing, it adds dangerous heavy metals to the leachate. The move to ban it from landfills seems more promising than banning plastic. It’s bigger and easier to sort out. Both technological and economic constraints hamper the progress of real e-waste recycling.
Some hopeful signs in solid waste disposal
Nevertheless, I see some very hopeful signs that involve the first fundamental changes in human attitudes toward trash since before the dawn of history. Trash can become a precious resource.
- Food waste and yard waste take up a lot of landfill space. States and municipalities are beginning to establish programs for composting it instead. Some of them make it mandatory, although that policy may backfire like the bag bans.
- Industry has developed biodegradable plastics. They won’t break down in your backyard compost heap. But they can be mixed with other organic wastes in industrial composting operations.
- As an alternative to composting, anaerobic digestion systems can turn organic waste to energy in various forms.
- Everything is potentially recyclable. Plastic bottles, for example, can be made into polyester fabric much more economically than making it from virgin petroleum.
- 3-D printing requires plastic, but it doesn’t require virgin plastic. At least one company, Filabot, makes a grinder that can reclaim several kinds of waste plastic to make the filament.
- A process called pyrolysis can convert waste plastic back to crude oil.
Do we have the technology to do all these things? Not yet, or at least not yet on a large scale.
Some landfills have pilot programs to develop various combinations of these and other innovations. I do expect to see impressive progress on all of them within my lifetime. In fact, I expect that some of them will become commonplace in my lifetime.
I have already expressed reservations about unintended consequences. But as we look to trash as a collection of resources instead of one big problem, unintended consequences may be easier to deal with.
10 recycling and waste management trends to look out for in the near future / Tom Szaky, Treehugger. June 14, 2014
Basic information about landfill gas / US Environmental Protection Agency
For education: history of waste management / Begin with the Bin
The history of waste: do you want to be a garbologist? / Roberta Cromwell Barbalace, EnvironmentalChemistry.com. August 2003
How landfills work / Craig Freudenrich, How Stuff Works.
Important things to know about landfill gas / New York State Department of Health
Municipal solid waste landfills / US Environmental Protection Agency
Rotten truth about garbage: a garbage timeline / Association of Science Technology Centers
Ancient Roman latrine. Public domain from Wikimedia Commons
Landfill diagram. Source unknown
Waste transfer station. Some rights reserved by ACE Solid Waste
Trash and recycling truck. Some rights reserved by fairfaxcounty
Bales of plastic for recycling. Some rights reserved by Lisa Yarost