Why did they put it on a train? Other than porta-potties, are there any other situations where poop isn't flushed into the sewers?
Do sewage plants normally haul away treatment byproducts as cargo? How much of this, if any, comes from treament processing plants and not ad-hoc plumbing substitutes? I'd figure only porta-johns would have this problem?
Where, exactly, do you think the poop goes once it's flushed into the sewers?
Sewers are not magical portals into another realm that we can just dump poop into forever. The sewers run to sewage plants where the water is extracted and treated to be sent back into the water supply. The poop that's left over has to go somewhere...
Human poop is by abitrary fractions, grease, plant fiber, bacterial biomass, ph imbalanced water and table scraps.
Processing plants deal with that, plus everything else people dump down the drain, or what fits without clogging during heavy rain.
The only reason the human excrement is not completely liquified is because digestive tracts are sensitive living membranes, and not chemical distillation vats.
Industrial processing is capable of leveling off the organic waste into salts with enough chemical action, and the grease can be processed through saponification. Our guts aren't capable of hydrolysis, over-boiling organic material until it's transformed and destroyed, or incinerating the waste in situ, but given that NYC has been dealing with the output of millions of toilets for over a hundred years, a brute force option like carting by train seems like a brainless, unsophisticated hack.
How does there come to be such an overflow that trains are the only option? It makes sense to me that porta-potties get handled in their own way, and if that's all this is, then I can see what happened. But if processing demands outstripped the capacity of on site management operations, I'd be interested to learn how that happened, and what leads to those conditions.
I'd figure big cities, like New York, all have had better infrastructure than this since at least the 1950's, when more options for advancing technologies appeared on the table.
These digester eggs presumably do more than just skim and filter purified water for recirculation:
http://www.nyc.gov/html/dep/html/environmental_education/dig...
The NYC sewage system dates back to 1850, with full coverage of the city only being achieved in the early 1900s. New technologies can and are added to the system (water treatment was introduced in the 1940s) - but there has never been a wholesale reconstruction of the sewer system.
[0] http://www.gothamgazette.com/index.php/environment/2005-the-...