Car wash effluent

There’s got to be loads of toxins coming out of a car wash; oil, antifreeze, deer parts, etc. does all of this nastiness just run through the same system as my poop?

yup, directly into flipper’s blowhole

This being the Straight Dope and all, I must point out that Flipper was a dolphin and opens his blowhole only when at the surface.

I laughed first though.

Okay, there’s a sewage treatment plant here in Durango. I know that they need to draw some amount of water from the river to make the magic happen. Why isn’t there a big plume of bleach and antifreeze floating downstream"

Part of waste water treatment is filtering chemicals out of the water before releasing it back into the environment.

Many car wash systems recycle their water so they get multiple car washes from the same water. It doesn’t particularly matter if the earlier soap cycles use ‘dirty’ water(it is physically filtered in most cases) The final rinse water should be fresh.

Here in LA, car wash ooze often flow right into the storm drain that has a picture of a dolphin on it. I’ve seen quite a bit of gross ooze floating down the LA river into the ocean.

missed edit window.

Here’s said picture of dolphin

Also, I’m pretty sure the car wash ooze isn’t supposed to go right into the storm drains (probably even a law), but I see it often enough.

There’s oil, antifreeze, deer parts, etc on the side of the road and in the storm drains too. I’m not saying it shouldn’t be treated, it absolutely should, but the crap in car washes is the same crap we spread everywhere, just collected in one spot.

Depending on where you live, car washes are required to have a filtration system, grease traps, etc., before they are permitted for use.

Depending on whether the car wash is in an urban or non-urban area the waste water will either go thru the sewage treatment plant like everything else or go into a septic leech field to be absorbed/evaporated. Local ordinances will vary widely but my guess would be that most commercial businesses are limited in what they can drain into rural septic systems.

Either way, if you’re concerned about ‘the environment’ the effluent from car washes is really really ***really ***low on the list of things to worry about…

In the U.K. it is law for car washes to have effluence treatment plant also any transport companies must have treatment plants before being allowed to wash their Vehicles

My father in law used to manufacture treatment plant

You have to start somewhere. Car washes are easy to regulate and inspect. Factories that dump suspect water into streams, not so easy. I saw a proposal once that all plant that draws water from streams should take water downstream from their outflow. Seems like a good idea to me.

What types of UK car washes are required to have treatment plants? I can see the automated ones having a system built in, but I’m pretty sure all the hand car wash places that have sprung up in the last few years are just draining into the regular sewer system. And the guys in the Tesco car park certainly aren’t treating their waste in any way.

Filtration is more likely to be found at water treatment plants, which treat water from rivers, wells, etc. before pumping it to your house. Wastewater treatment plants use settling tanks (primary treatment), biological processes (secondary treatment - one secondary treatment is a “trickling filter”, but it’s not filtering anything), and chemical and/or UV processes (tertiary treatment).

There can be secondary settling tanks after the biological treatment. The bits that settle or float in the settling tanks (formerly sewage sludge, now “biosolids”) are sent to anaerobic digesters. After anaerobic digestion, the digestate is dewatered before disposal to reduce volume. That could be called filtering, but it’s not really a treatment.

Basically, if a chemical isn’t eaten by the microbes in the secondary treatment tanks and isn’t deactivated by a dose of chlorine and/or UV, it’s going to go straight through. Filtering traps grit and silt. It’s not possible to filter anything that’s truly dissolved. On the up side, the bio-treatment and chlorine do knock out a lot of chemicals.

The water from the treatment plant should be tested for chemicals. And if chemicals are found then the water should be treated. And the personal in the plant will back track the system to determine where the offending chemicals came from.

Hand wash at petrol stations are covered as all run off from the forecourts has to be treated and many supermarkets have garages so there again they are covered as for some of the so called independents some may not legally excist

Think about this: Every time it rains every single car is essentially being ‘rinsed off’. No, there aren’t any soap agents applied, but every bit of grease and oil from billions of cars and every bit of road treatment material (salt, de-icing, asphalt etc.) is being rinsed off and funneled directly into the ground everywhere all the time. Not to mention every single outdoor surface of every single industrial establishment everywhere in the world.

You need to come to terms with what it means to live in a modern, industrialized society…

Not a chance. At least not for “chemicals”. There are hundreds of thousands of possible chemicals and millions of gallons per day coming through a mid-sized treatment plant, which will be treating mostly domestic waste.* No one is going to spend billions per year per treatment plant running tests fishing for possible chemicals.

Treatment plant effluent is mostly tested for BOD5**, COD5***, ammonia, phosphorus, and (if the sewage was treated with it) chlorine. The plant lab will also test for pH and turbidity. Some plants do “toxicity” tests, which I’m guessing involve small fish.

Now I mentioned that the secondary treatment process is a biological one. If something comes through that knocks out the microbes doing the work, the plant operators will go searching. It takes a lot to knock out a unit, though.

Oh. Know what some ecologists are worrying about? Residual hormones from birth control. Women pee the hormones out and traces make it through most plants. They think it can interfere with the development of fish and amphibians. Studies are ongoing.

*Typically. Industrial wastewater requires more scrutiny. That scrutiny is more productive at the source.

** Biological Oxygen Demand (5 days) is basically a test to determine how much nutrient value is in left in the effluent after treatment. Nutrient feeds bacteria and bacteria pull oxygen out of the water as they digest it. Effluent flows into some receiving water body. If there is too much BOD, the receiving waters can go anoxic from the bacterial bloom.

*** Chemical Oxygen Demand is a similar test, but while BOD is determined by incubating bacteria in water samples, and takes 5 days to run, COD uses chemicals to react with the nutrient for a quick and dirty approximation.