hi, I have a question.<br />One of your edited sentences (see below), I think that the verb should be "are" not "is" becuase the subject "amounts" are plural. Can you please check and let me know soon, which one is correct?<br /><br />In anaerobic digestion, significant <strong>amounts</strong> of a gas, CH<sub>4</sub>, <strong>is</strong> produced, which can be used as fuel and for treating highly contaminated wastewater"