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<p>In this paper, one partial nitritation system with biological selector (PNBS) was first evaluated in treating high-strength ammonia containing wastewater. Nitrite production rate (NPR) of 8.25 kg N m<sup>-3</sup> d<sup>-1</sup> was achieved with influent NH4-N concentration 2000 mg l<sup>-1</sup> and HRT 3.2 h, which is, to our knowledge, the highest NPR to be treated successfully by an nitritation reactor. A genetic analysis of the organisms in the PNBS revealed an abundance of Nitrosomonas sp. ENI-11, Uncultured bacterium clone: AnDHS-3, Nitrosomonas sp. ENI-11 and Nitrosomonas eutropha enriched in the PNBS reactor.</p>
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