Rivers clean themselves quickly when pollution is not too great, so long as the water is moving and in contact with plants, soil and rock.

在污染不太严重时，河水只要是流动的而且能接触植物、土壤、岩石，自身很快就会变清洁。

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Aiming at serious pollution and no good biochemical quality in refinery alkalinity waste liquid, using hydrolysis-contact oxidation process to treat it.

针对炼油废碱液污染浓度高、可生化性差的特点，采用水解与接触氧化组合工艺进行处理。

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The rotor has no contact with any parts in operation. There is no pollution. The operation is reliable, continuous, stable with strong suction, low noise.

叶轮运转不与任何零部件接触，没有污染，工作可靠，吸力强劲、连续工作、噪音低、工作平稳。

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Gypsy-gadje relations are made even trickier where traditional groups still observe laws shaped by a sense of imminent defilement, the idea (more understandable when framed within an Indian caste system) that contact with gadje, particularly sexual contact, is a kind of pollution punishable by banishment.

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