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A combined ammonia gas absorption and nitrification was conducted in a single bioscrubber. The reactor was consisted of a bubble column (gas absorption) and a packed bed (nitrification) which contained poly-urethane foams with immobilized nitrifying activated sludge. The entering gas and scrubbing liquid were contacted countercurrently. The bubble column elimination capacity (EC) was 26.74gNH₃/m³h at >99% ammonia gas removal and effluent gas concentration lower than 2ppm_v. Without ammonium supplement, EC can reach 35.66gNH₃/m³h which is equivalently the highest tolerable ammonia loading rate of 700gN/m³day (1650mgN/L) at the packed bed. At this level, 593gN/m³-day ammonia removal rate was achieved via nitrification, dominated by ammonia oxidation. Partial recycling (R/Q=0.5) of scrubbing solution reduced the secondary wastewater volume by producing 233% more concentrated …