Treatment of high-strength rare-earth ammonia wastewater with two-stage anammox process

In this study, a two-stage anaerobic ammonium oxidation (anammox) system—including a partial nitritation system with a biological selector (PNBS) and a granular activated carbon-based granule anammox process (GAP) —was used for the treatment of real high-strength rare-earth ammonia wastewater (HRAW). A nitrogen removal rate of 89% on average was achieved at the end of the study with the influent total nitrogen concentration of 2200 mg l^-1. The nitrogen-loading rate (NLR) of 17 kg N/(m³×d) was achieved in the PNBS, and a reduced NLR of 6 kg N/(m³×d) was maintained in the GAP. To our knowledge, this is the highest NLR applied to a two-stage anammox system. A genetic analysis of the sludge samples revealed that a Nitrosomonas sp. was enriched in the PNBS reactor, while, Kuenenia stuttgartiensis_, Uncultured bacterium clone KIST-JJY001, and Uncultured anoxic sludge bacterium KU2 were enriched in the GAP reactor.