求翻译：加入活性炭和氧化镧和对体系的除铁和除硅效果明显，二者单独添加时分别使铁的含量由25ppm降低为8ppm，使硅的含量由32ppm降低为7ppm；是什么意思？

Adding activated carbon and lanthanum oxide and the effect of the system in addition to iron, and in addition to silicon, both when added alone, respectively, the iron content reduced from 25ppm to 8ppm, the silicon content reduced from 32ppm for 7ppm;

To join lanthanum carbonate and activated carbon and carbon dioxide in addition to the rail system and in addition to silicon in 2, when added to separate the content from 25 ppm to 8 ppm of silicon content, as 32 ppm to 7 ppm;

Joins the activated charcoal and the lanthanum oxide and is obvious to the system except the iron and except the silicon effect, the two alone increase when respectively causes hard the content to reduce by 25ppm is 8ppm, causes the silicon the content to reduce by 32ppm is 7ppm;

Add activated carbon and system of iron and lanthanum oxide and Silicon effect is clear, both individually while the iron content from 25ppm to reduce 8ppm, Silicon content by 32ppm reducing 7ppm;

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