Spoiler alert: Clearly, composting is way better for the environment than using the garbage disposal, and it costs less as well.
Composting keeps the garbage from ending up in a landfill, where it generates much more methane, a greenhouse gas. Composting saves using up space in the landfill. And, composting actually creates a valuable resource – fertilizer for home use and for commercial farming.
What’s so bad about using the garbage disposal?
Well, as we just mentioned, food that goes into the garbage disposal ends up in waste water, which must be pumped through the system, then subjected through a multi-step process of filtration and disinfecting. The final products are water that’s released into local waterways, where it’s used again for any number of purposes, such as supplying drinking water, irrigating crops, and sustaining aquatic life, and “biosolid” residue.
Truth is, “biosolids” is a marketing term, a euphemism for sewage sludge. Sometimes, that biosolid is sold as compost, which has been controversial, since it may contain industrial chemicals, medical waste, oil products, pesticides, home cleaners, etc. Other times, that residue is headed for – you guessed it – the landfill.
Of course, you’re running water while running the garbage disposal, so you’re using more water than necessary – wasting water, and adding more water to the sewage system, which then needs to be processed and filtered out.
Food waste can also cause plumbing problems, as most everyone has experienced. Food waste that contains unsaturated fats solidify at room temperature and can build up inside your pipes, causing clogs – very inconvenient, and possibly very costly.
So, putting your food scraps in the garbage disposal uses extra water, could possible clog your pipes from time to time, requires a lot more energy for processing, and often ends up in the landfill anyway.
So, should we consider putting those food scraps in the regular trash?
Uh, no. The more important reason to keep food scraps out of the landfill is that, as they break down, they generate much more methane gas than if they’re composted. Composting does generate carbon dioxide (another greenhouse gas), but methane causes 30 times more heat buildup in the atmosphere than carbon dioxide, so causes a lot more environmental damage. (That’s why you hear so much about methane-producing cattle being such an environmental problem.)
Yes, there have been improvements in capturing methane from landfills, but it’s a difficult process, with many problems, and is not very widely used yet. Preventing methane generation in the first place is much more effective.
Is using the garbage disposal ever a good idea?
Definitely, yes. If you live in an area where curbside compost pickup is not available, and you’re not interested in backyard composting, grinding up those food scraps in your garbage disposal is still much better for the environment than tossing them in the regular trash bin, for the reasons we mentioned above – specifically due to the considerable methane gas that the food scraps in the landfill generate. We always want to keep food scraps out of the landfill.
Can’t the solids from wastewater be sold, to offset the processing costs?
Solids from wastewater are either dumped in landfills, incinerated, or sold cheaply or given away for fertilizer. According to an article in the Guardian, “In 2019, about 60% of sewage sludge produced by treatment facilities will be spread on farmland and gardens, as well as schoolyards and lawns.” Sounds like a viable solution, right?
They also noted that, “the waste management industry lightly treats it and sells it cheaply to farmers who view it as a cost-saving product.” But, they also note, the sludge contains “any number of 80,000 manmade chemicals that are discharged from industry’s pipes or otherwise pumped into the sewer system”. In order to really process that sludge sufficiently, it would much more expensive processing. Therefore, selling the biosolid is not really cost-effective.
But, doesn’t collection and hauling that composting material cost money, and generate pollution?
Yes, it does. So, if you’re a backyard composter, that’s an even better way to handle food scraps. However, non-gardeners don’t really have a need for the compost, so municipal composting is a far more environmentally safe solution than the alternatives – the garbage disposal or regular trash bin.
Doesn’t composting generate methane too?
Yes, composting does generate some methane. According to Moonshot Composting, “Any time organic materials (like food scraps) decompose, they can be expected to produce methane and carbon dioxide. The more air included in the composting process, the more carbon dioxide that compost emits instead of methane.”
Since methane is 30 times more negatively impactful to our environment than carbon dioxide, any process that minimizes methane generation is better. Aerobic composting – introducing oxygen into the composting process as is done in both backyard composting and commercial composting – results in far less methane generation than anaerobic breakdown – like in a landfill.
Is backyard composting better than curbside compost collection?
Definitely yes. Backyard residential composting is the best solution overall to dealing with food scraps. All composting does generate some methane, but properly aerated composting
- You know it’s organic, so safe for your vegetable garden
- There are no transportation costs, and the associated air pollution generated
- There’s no methane production.
So, the choice is clear – compost your food scraps, however possible. If you can’t do that, drop them in the garbage disposal. As we’ve seen, mixing them in with your regular household trash is the worst option.