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This water needs a good wash before it ever reaches your faucet.
自来水在从水龙头流下来之前要经过反复洗涤。
Whether you are treating for a population of 3000 or for 3 million, this process is going to look a lot like this.
不管供水的人口是三千还是三百万，水处理过程都类似下面这样。
It's called conventional water treatment and it makes lake and river water safe to drink.
这叫做常规水处理，它能使湖水和河水变成饮用水。
It starts with a chemical that attracts and binds together the stuff you want to take out.
我们先加入化学试剂，它能够将我们要清除的脏东西混合在一起。
We add those coagulant and it's positively charged where most of the dirt and bacteria have negative charge.
我们加的沉淀剂是带正电荷的，而泥土和细菌是带负电荷的。
It's a crucial if temporarily backward step.
我们虽然让它暂时变脏，但这却是重要一步。
When we added our coagulant, it actually made the water dirtier.
当加了沉淀剂之后，水更浑浊了，
We created these flocks but now as we are going, all those flocks are settling out.
并产生了许多废渣，但随着我们向前看，这些废渣也已经分解开来。
This process sedimentation makes the things you don't want to drink sink,
沉淀过程让你不想饮用污水，
a key step in creating cleaner water for you and for the rivers.
不管是为人类饮用还是河流水质，这都是获得清洁水的重要一步。
This is all part of the process that diverts those salads should be returned to the river and put beneficial use instead.
这步是使需要回到河流里的混合物被分流回去，并使它们派上用场。
In this case the solids will coat a landfill. Now back to the drinking water.
然后这些固体物将会填充泥土填筑池，回到正题上，接着说饮用水。
There are some fine small particles that can float on that aren't removed by gravity settling and here is where we remove those small particles.
有些微小颗粒用刚刚的重力沉淀法没有去除干净，现在我们看到的就是去除这些微粒的方法。
The technical name is dual media filtration which means that within any one filter,
这个技术名叫双向过滤法，意思是在一个过滤器中，
water flows through both coal and sand in case you wonder how they clean those filters: backwash.
水流穿过煤块和沙子，如果你纳闷水是如何被清理干净的，那就是“反流法”。
In the next step, filtered water is disinfected by adding chlorine.
下一步骤，氯将被用来为过滤水消毒。
Each step is lab-tested, something important in times of erratic weather.
每一步都是实验室检测过的，如果要赶上恶劣天气，有了它还是非常有保障的。
If you've got a lot of rain in the watershed, it can stir up dirt and debris and carry that into the river.
如果集水区的雨水太多，就会有多余的泥土残渣被冲到河里。
When that's taken into a water treatment plant,
所以当这种水被排入水处理厂中时，
you need to increase your coagulant dose to account for that higher amount of solids in the river.
就要相应的多加沉淀剂，确保固体沉淀的量也相对增加。
Engineers at this cutting-edge treatment plants say
尖端污水处理厂的工程师说，
modern technology can keep today's drinking water cleaner and safer than any other point in history.
现代污水处理技术处理过的饮用水比历史上任何一个时期的水都要干净。
Arash Arabasadi, VOA News, Washington.
美国之音，阿拉仕·阿尔芭沙迪在华盛顿为您报道。
