Question

please help me with this question
_____________ is achieved when biological action allows _________ to substitute for hydrogen in ammonia-containing wastewater. 

Ammonification; nitrogen  Denitrification; chlorine 

Denitrification; oxygen  Nitrification; oxygen

Answer 1

i would say it is:
Ammonification is achieved when biological action allows nitrogen to substitute for hydrogen in ammonia-containing wastewater. 

Answer 2

thank you

Answer 3

your welcome :)