Performance and control of PD/PN/Anammox coupling process pilot for ammonia nitrogen wastewater in rare earth mines at low water temperature
The new biological nitrogen removal process of wastewater based on anaerobic ammonia oxidation(Anammox)has great challenges in stable operation at low water temperature.In this paper,according to the water quality characteristics of ammonia nitrogen and nitrate coexistence in ammonia nitrogen wastewater of ion-type rare earth mine,a coupling process of partial denitrification(PD),partial nitrification(PN)and anaerobic ammonia oxidation was constructed.A 50 m3·d-1 pilot scale test device was constructed at the mine site,and the experiment was carried out under the condition of low water temperature in winter for 108 days.The results showed that the average ammonia nitrogen removal rate(ANR),the average total nitrogen removal rate(TNR)and the average total nitrogen removal load(TNRR)of PD/PN/Anammox coupling process were 95.64％,84.27％,and 0.19 kg·(m3·d)-1.When the water temperature drops from 22±2 ℃ to 10±2 ℃,the system capacity decreases from 32 m3 d-1 to 16 m3 d-1.The boundary line of the influence of water temperature on each reactor is 15 ℃.When the water temperature is lower than 15 ℃,the reaction rate decreases obviously,and the nitrite accumulation rate(NAR)and nitrate removal rate(NRE)fluctuate.In the low water temperature environment,the control strategies such as increasing C/N,extending hydraulic retention time(HRT),adjusting intermittent aeration time and adding organic carbon sources were adopted to effectively alleviate the impact of low water temperature.The high-throughput sequencing results showed that the relative abundance of functional bacteria Thauera,Nitrosomonas,Candidatus_Kuenenia,and Candidatus_Brocadia decreased due to short-term impact of low water temperature,while the relative abundance of functional bacteria increased normally during long-term operation.Functional bacteria can be normally enriched under long-term low water temperature(10±2 ℃).
partial denitrificationpartial nitrificationanaerobic ammonia oxidationammonia nitrogen wastewater from rare earth mineslow water temperaturepilot scale
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