Environmental considerations: garbage disposal vs. trash can

Reminded by this thread Things that can’t go in the garbage disposal, I’m posting something I’ve wondered about. (Here in GQ, hoping somebody can give a real answer. But maybe it belongs in IMHO.)

Trying to be conscious of environmental concerns for our planet, which is a better way to dispose of kitchen waste: an in-sink garbage disposal or a kitchen trash can?

From the garbage disposal, they are chopped up and go down the pipe, eventually to the sewage treatment plant. That treats the water and then sends it down the Mississippi to Iowa, etc., while the ‘solids’ are removed via settling ponds and then either incinerated (generating electricity) or ‘pasteurized’ via a heat/lime dust process and then used as fertilizer on farm fields. A fair amount of clean water is used up in this process, since you are supposed to leave the water running while grinding things up in the garbage disposal. And a small amount of electricity to run the motor. But I don’t think there is much oil-based transit involved, since this is transported via the sewage system, mostly running downhill without too much pumping.

Throwing them away in the kitchen trash can means that they are gathered into plastic trash bags and put in the garbage bin. Then each week a garbage truck comes down the alley and picks them up. They are trucked to a centrally-located incinerator that burns the garbage and produces energy & heat for downtown buildings. The ash remaining after the garbage is burned is buried in watertight landfills.

(Composting might be an alternative, but I don’t have a compost heap, I probably wouldn’t generate enough waste to keep one going, and I understand that food waste, especially cooked food, should not be put into compost heaps anyway. So that option isn’t very feasible for me.)

So which of these is better, environmentally?
And, please, I’d prefer answers based on evidence & cites rather than opinion, if possible.

I posted this link in the other thread.
According to a University of Wisconsin study

What really amazed me was the difference in costs attributed to the different disposal methods.

Now the study did not take into account the composting of garbage by the homeowner, but I doubt you could get 100% of the homeowners do that.

The other thing to take into account, however, is the increased organic loading on the wastewater treatment plant when food disposers are used. Many wastewater treatment plants, especially older ones, are already at or near capacity, and the regulations have only been getting stricter.

For example, the latest regulatory emphasis has been on addition of denitrification processes to reduce the discharge of nitrogen-based nutrients to the receiving waters (which encourages algae blooms and anoxic conditions, which kills fish). Adding food based waste to the wastewater stream makes it more difficult to meet these standards.

The net result is that many municipalities here in the Northeast are discouraging and even banning the use of food disposers. (Enforcement can be a problem, however.) Many municipalities here have had education campaigns that include the admonition that “Your toilet and sink are NOT a garbage can!”

Any cost analysis therefor has to take into account the fact that expansion and upgrades to wastewater treatment plants can easily run into the tens to hundreds of millions of dollars.

On the other hand, if you use a food disposer with an on-site septic system, you are also asking for trouble. Food disposers can easily clog up leach fields, requiring costly replacement ($10K to $20K).

Incidentally, I tend to question any study commissioned over a decade ago by the “National Association of Heating-Plumbing-Cooling Contractors.” :rolleyes: And was Carol Diggelmann (the person who did the research) a graduate student or a Professor, exactly? I ask this because these two positions are about 20-30 years apart in the typical career progression.

–robby (Civil/Environmental Engineer)

Twenty years apart? :confused: I had a couple of professors that were under 30, so unless they started college when they were still in diapers…
Since she was not listed as a Dr., and since she was listed as a prof at one college and a student at another, I am guessing she was teaching while working toward her doctorate.

if you check the link, there are several other studies listed including one by the Dutch government, Sydney Australia, and the City of New York.

The city of NY doesn’t seem to agree with you.

The link listed the researcher’s title as a capitalized Professor, as in a full, tenured, Professor. This is as opposed to a Lecturer, Assistant Professor, or Associate Professor.

I guarantee that no reputable research university in the U.S. has any professors without a doctorate, much less a full Professor.

From the wiki link above:

Doing a quick skim of your link I don’t see any differentiation between professor and a Professor. in some parts of the article they talk about assistant professors and in other parts Assistant Professors. Like wise with full professors and Full Professors.
::: Shrug:::
Taking the link from that article to the one on Academic Rank all levels of professorship are capitalized.

Do you have a cite from something that says there is a difference between a professor and a Professor?

In the case of my profs, we just called all of the instructors prof or professor. Some of my younger profs had PHDs and were called doctor. Others did not have PHDs, and were called Mr. or Ms.

Common usage dictates that titles are capitalized. Conversely, if a position is capitalized, it indicates that it is a person’s title.

Also, there’s no such rank as a “Full Professor.” The wiki article and I in my previous post simply used that terminology to distinguish the academic rank from a generic “professor,” who could indeed be an Assistant Professor or an Associate Professor.

If a person’s title is “Professor,” capitalized as in your link, that means they are a (full) Professor. As I mentioned previously, no graduate student is a Professor. In fact, I doubt that any grad student is a professor of any sort in a major research university.

It’s the same thing as in the military, as distinguishing between a “general,” who could be a Brigadier General (O-7), a Major General (O-8), or a Lieutenant General (O-9), as opposed to the actual rank of “General” (O-10). To distinguish a generic “general” from the rank of “General,” the latter is often referred to as a “4-star general.” Similarly a Professor may be referred to as a (full) Professor, to distinguish this academic rank from that of a generic professor.

In any event, I don’t think anyone familiar with academic ranks could look at a sentence like “The research was conducted by Carol Diggelmann, a graduate student and a Professor at the Milwaukee School of Engineering” and not raise an eyebrow.

Incidentally, the Milwaukee School of Engineering doesn’t even offer engineering Ph.D. programs, and apparently is not a research university either.

Back to the main topic, Rick, note that your link compares the cost of municipal solid waste collection versus that of a publicly owned treatment works (POTW).

Not only does such a cost comparison ignore the cost of upgrades to POTWs if they are near capacity, it also ignores the fact that many municipalities do not pay for municipal solid waste collection. Instead the cost is borne by the residents. For example, in my community, you can either pay Waste Management to collect your solid waste, or haul it to the town transfer station and pay by the volume of trash you are disposing.

In such a situation, since the municipality is not paying for solid waste disposal, but is paying for the POTW and any upgrades that may be necessary, the municipality would prefer that food disposers not be used.

BTW, Rick, did you not notice that the studies presented in your first link are all on a site run by a garbage disposer manufacturer? :rolleyes:

InSinkErator builds garbage disposals? No shit? Why wasn’t I informed? Here I thought they were part of Greenpeace or built airplanes or something. Who knew? Somebody should alert the media. :rolleyes:

So you are saying that a study by the New York Department of Environmental Protection is not worth anything because it is cited by a garbage disposal manufacturer? :dubious:

So far in this thread, I have quoted two studies* and a link to where other studies done for the Dutch government, Sydney, Australia, and Utanobori, Japan can be found.

You on the other hand, have presented your opinion, and have spooled of into outer space over if there should be a capitol P at the beginning of professor. :confused:

Your contention that garbage disposers will cause new waste treatment plants to be built is directly contradicted by the City of New York Report which I quoted above. Here it is again

So if I am reading this right, what the City of New York is saying is that if you have a water treatment plant built in the 1950s and in 2007 the Feds change the water quality rules, then guess what, you are going to have to build a new plant. Since the old one just isn’t going to cut it any more. The presence of lack of food waste disposers is just a fart in a whirlwind compared to the load caused by increased population and tighter regulations.

As far as costs go, no matter where you put the garbage the homeowners are going to pay for it. Either to a private trash company, or to the local city, county, town whatever is taxes and or fees. That is the nice part of the UW study is it looked at the life cycle costs of the various methods.

Now I can see where if a city had an outmoded marginal waste treatment facility that they might want to discourage the use of FWD as it might allow them to eek out an extra year or so before they have to spend some money on upgrading the facility. The bottom line is that their treatment facility is marginal, and will need replacement if for no other reason than the population is increasing and this alone will cause the facility to become obsolete.
Now just because the employees of a city or water district are arguing against using FWD in an effort to eek out a little extra time before they have to bite the bullet and build a new plant, this does not make their campaign either right or the correct move from an environmental point of view. It just means they are trying to keep the system working when the politicians either can’t or won’t find the money to fix the underlying problem, ie the treatment plant is out of date and marginal.

*yes one was paid for by the National Association of Heating-Plumbing-Cooling Contractors. But the other was done by the City of New York which the last time I checked was in the Northeast.

You know, if you read your own links, you’d see that most of the so-called harmlessness of food disposers is simply because of low expected market penetration.

From the InSinkErator postion paper:

Also, from the postion paper, they note the increased organic loadings, but contend they are not a problem because expected market penetration is relatively low. This does not equate to their use being of negligible impact, as you contend, particularly as market penetration increases.

Agreed, but that’s not how small towns look at the issue. Also, you still seem to think that POTWs can absorb all of the extra organic loading with no associated cost.

Again, that’s small town politics for you. Also, substitute “an extra year or so” with “an extra decade or so.” The fact is that many small municipal POTWs are marginal now, and may be exceeding regulatory standards now during periods of peak use. Food disposers do not help, and encouraging their use if you live in an area where the existing wastewater treatment system is marginal is irresponsible. Also realize that there are many marginal systems out there.

It’s a stretch comparing high-population density areas like New York City, the Netherlands, and Japan to low-density munipalities in New England, where I work. You can’t just say that New York City is in the Northeast, so therefore is comparable to New England small towns.

I finally got around to looking at some of the various studies presented in Rick’s In-Sink-Erator link:

The first study is entitled, "A BRIEF SUMMARY AND INTERPRETATION OF KEY POINTS, FACTS, AND CONCLUSIONS FOR University of Wisconsin Study:

There aren’t enough rolleyes possible for this one. This is the one in which the “research” was conducted by the grad student/Professor. We aren’t shown the actual paper, however, nor are we given a summary prepared by the study authors. Instead we get a mish-mash of a summary from some In-Sink-Erator staff engineer. The dollar figures cited by Rick are there, but with no justification for how they were determined. Nor do the costs make any sense. The “Total System Cost” for the Food Disposer/POTW combination is comparable to the other alternatives, but then the figure for “Public municipality cost (external to the home)” is dramatically lower for some unexplained reason. As I stated before, even this is misleading, as it ignores costly upgrades to handle the increased organics loading, especially at higher market penetration.

This is not rocket science, you know. Whether you flush human waste down the toilet or chop food waste down the sink, solids and organics going down the drain have to be dealt with by the treatment plant. What’s left at the treatment plant is referred to as sludge, and it has to be dewatered at great energy expense, and is then typically hauled to a landfill. (Sludge is rarely used as fertilizer because of the tendency to be contaminated by metals and other pollutants people typically [and stupidly] put down the drains.)

The Dutch study summary is very short, and only considers very low market penetrations of 5-10%.

Next we have the Australian study. Despite the fact that it was prepared for In-Sink-Erator, as stated on the title page, it actually looks fairly reputable. Here are some highlights. Note the repeated caveats about keeping market penetration relatively low.

Considering operation impacts of Food Waste Processors:

Next it addresses the original question of the OP, as the study considers the environmental impacts of FWPs as compared to home composting, co-disposal with municipal waste, and centralized composting:

Finally, the study compares cost comparison of the food disposal options, which directly contradicts the ridiculous figures that Rick keeps posting from the University of Wisconsin “study”:

Which of course is what I’ve been stating since my first post.

I’d post more about the other studies, but I think I’ve made my point, and I’m going to bed.

I know the OP mentioned and discounted composting, but for people without a compost heap and who only generate small quantities of waste, worm bins are a good way of dealing with it.

(The link is a make-your-own page, but you can buy them ready made and filled…)