We've detected some chemicals that can make it through the first step in the process, but by the time we get to the second step, the advanced oxidation process, we rarely see any chemicals present.
我们发现某些化学物质 无法在步骤一被过滤掉， 但经过第二步： 高级氧化过程之后， 几乎没有化学物质能残留下来。