环境工程专业英语中IER是什么的缩写

Question

并帮我翻译：The height of these vessels varies between 6 and 10 feet to provide adequate resin storage, distribution nozzle layout, and freeboard capacity for bed eapansion during backwashing.
谢了。

Answer 1

看文章中提到的，很可能IER是Ion Exchange Resin（离子交换树脂）的缩写。