This method was uneconomic for it was impossible to recover the spent acid.

由于不能回收废酸，所以这个方法是不经济的。

youdao

Spent acid after cleaning plated parts is great in quantity and can not be treated desirably in plating factories.

清洗镀件后的废酸在电镀厂中数量巨大，但又没有良好的方法加以处理。

youdao

The method of utilization of industrial spent acid and rejected copper and Zinc oxide ore is concerned in this paper.

本文涉及工业废酸资源化和废弃的氧化铜锌矿资源综合利用的方法。

youdao

Portugal, a father of six who owned a small accounting and tax firm in Queens, was burned with acid and spent the better part of a month with his head cloaked, authorities said.

WSJ: NYPD: Merchant held for ransom, tortured for month

Dido spent the next 18 months going through the same things as every other parent - sleepless nights, acid reflux, and a thorough grounding in CBeebies.

BBC: Dido interview: 'I am the sound of conflict'