Nitrogen removal from hypersaline wastewater
was successfully started up by inoculating estuarine sediments
for 140 days. Efficient ammonia and total nitrogen
removal was sustained under specific ammonia loading of
0.016–0.139 kg N/[kg VSS day] in a sequencing batch
reactor. Stable nitrite accumulation was observed during
nitrification. The specific ammonia consumption rate was
higher than the value of freshwater activated sludge and saltacclimated
freshwater activated sludge. With methanol as
carbon source, specific nitrite reduction rate of halophilic
denitrifiers was much less than the freshwater counterpart.
Halophilic activated sludge was characterized as good settling
and flocculation prosperity with small floc size and netlike
sludge structure. The abundance of ammonia-oxidizing
bacteria outnumbered ammonia-oxidizing archaeas in both
estuarine sediments and the activated sludge. Nitrifier population
was dominated by the halophilic members of genus
Nitrosomonas
. This study demonstrated the application of
mixed halophilic consortia for efficient nitrogen removal,
overcoming the limits and difficulties of applying freshwater
bacteria for saline wastewater treatment.