Hello again, readers! I’m finally rejoining the world of blogging, now that it’s been nearly 6 months since my last post. In the meantime, I got married and changed my name — I’m now Claire Farnsworth Wildman, but otherwise blog content should remain unchanged. I’m going to try to get into posting again once a week, and throw some links on my twitter feed when I can’t get to posting on interesting news. Hopefully this will work!
So today’s post is a comment on China’s limited water supplies. Bloomberg is noting that China’s coal mines are beginning to feel the crunch of limited water. China has a fundamental problem that a bunch of development (agriculture and cities, and apparently many coal mines) is in the north, whereas the majority of their rainfall and streamflow is in the south. This is not too different from the issues of the American southwest, where cities in dry areas keep expanding on the premise that they can access water from distant snowfall in the Rockies or Sierras via rivers and aqueducts.
The difference is that the US generally has pretty decent water resources (9,044 cubic meters = 2.4 million gallons per capita), but China’s are relatively sparse (2,093 cubic meters = 0.55 million gallons per capita), so moving water around won’t ultimately resolve all of their issues.
What struck me in the above article, though, was this: “…Veolia Water, which treated 1.2 billion tons of waste water in China last year…” That sounds like use of numbers to imply large volumes of treated wastewater…but remember, China has 1.354 billion people as of January 2013. So, one of the world’s largest water and wastewater treatment plant operators treated nearly 1 ton of wastewater per capita in China last year. Let’s put that in perspective: an American city with low water use has about 150 gallons per day per capita, which we can assume goes to the wastewater treatment system. This number is probably way too high for per capita water use for places without reliable drinking water supplies, but let’s use it for a back-of-the-envelope calculation:
150 gallons/day/person x 365 days/year x 8.34 lbs/gallon / (2000 lbs/ton) = 228 tons of wastewater per person in the US
Ok, again, very rough numbers. Per capita water use is tricky to measure, but this website cites a 2006 UN Development Program report to suggest China averages something like 23 gallons/day/person (quoted as 86 liters/day/person). Plug that in to the above equation, and you come up with 34 tons of wastewater per person in China, not including industrial wastewater. Again, one of the world’s largest wastewater treatment companies was proud to hit the target of ~1 ton per person last year. Whatever the per capita water use in China, it sounds like wastewater treatment has a long way to go…