Economical and effective control of pollution by ammonia-nitrogen waste water is a vital problem currently.

经济有效地控制氨氮废水污染是当前面临的重大课题。

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Economical and effective control of pollution by ammonia-nitrogen waste water is a vital problem currently.

经济有效地控制氨氮废水污染是当前面临的重大课题。

youdao