refractory COD是什么(水回收)? The contaminated streams will become more concentrated as goodquality water is recovered. If we take a typical industrial effluent with a refractory chemical oxygen demand (COD) of around 50 mg/l, this is concentrated to an average 250 mg/l in a RO system recovering 80% of the feed. At this concentration, the effluent is no longer compliant with any of the discharge standards as shown. 请问标红的 refractory 何意? 查看更多2个回答 . 3人已关注