Nitrogen and sulfide removal from effluent of UASB reactor in a sequencing fed-batch biofilm reactor under intermittent aeration

► Nitrogen and sulfide removal from effluent of UASB reactor treating domestic sewage. ► Sequencing fed-batch biofilm reactor under intermittent aeration for post-treatment. ► Start-up and feeding strategies for simultaneous nitrification/denitrification. ► Lower nitrification efficiency in favorable autotrophic denitrification conditions. ► Elemental sulfur accumulation and requirement of external alkalinity addition.