Based On Nitritation-anammox-denitrification In Treating Ammonium Rich Wastewater Of Iron Oxide Red

Iron oxide red wastewater?IORW?is a kind of acid industrial and low C/N ratio wastewater that contains large amount of ammonium,sulfate and Fe²⁺.Traditional nitrogen removal technology needs consume carbon sources and sulfate reducting bacteria?SRB?can also use carbon source convert sulfate to H₂S that easily cause second pollution.This study developed nitritation,sulfate-anaerobic ammonia oxidation?S-anammox?,nitrite-anammox?N-anammox?and autotropic nitrogen removal technology to reduce most ammonium then followed by denitrification with relative few carbon sources.The main results and conclusions as followed:?1?Different nitritation rate was investigated via the regulation of alkalinity dosage in zeolite biofilm aeration filter?ZBAF?.Generally,Na HCO₃ and Na₂CO₃ are the common alkalinity donors for nitrification and have the same selling price while the later provides alkalinity about 1.67 times to the former with the same dosage.But,Na₂CO₃ can easily lead to higher p H value than Na HCO₃ then cause inhibition to ammonium oxidation bacteria?AOB?from high-level free ammonia?FA?.Base on the relationship between influent alkalinity/ammonium ratio?mass concentration?and nitritation rate,a non-linear model was used to simulate the alkalinity regulate nitritation.When influent alkalinity/ammonium=4.33that effluent nitrite/ammonium was in the range of 1.0 to 1.4 which was suitable for the further treatment via anammox.Moreover,using Na₂CO₃ in ZBAF can lead to zeolite harden and block make frequent backwash was required and this can destroy the biofilm and has disadvantage to the system recovery and hard to maintain the stabilization of effluent.Therefore,we attempt to use a zeolite membrane biofilm reactor?ZMBR?to solve the above mentioned.ZMBR can maintain higher nitrogen loading rate?NLR??2.78 kg N/?m³·d??compared with two-stage ZBAF?1.46 kg N/?m³·d??under the same nitritation rate.Biofilm formation can easily take place on the zeolite and the q PCR detection revealed that AOB and NOB co-exist on the biofilm while the more copy numbers from AOB?2.40×10⁹/?L DNA?than NOB?7.75×10⁷/?L DNA?.?2?S-anammox was startup by using?NH₄?₂SO₄ instead the influent substances of N-anammox and then feed with IORW only.When cultivated to 185^th day,the nitrogen removal rate?NRR?was 0.23 kg N/?m³·d?by influent NLR with 0.28 kg N/?m³·d?and TN removal was 82.4%.The relative abundance of Ignavibacteriaceae?the landmark bacteria of S-anammox?increase from 0.35%to 6.11%revealed that the startup phase was a time-consuming process and influent ammonium concentration and FA concentration in reactor were the main influence factors.We believed that influent ammonium was no more than 200 mg/L and FA in reactor should below 15 mg/L that can be beneficial to the acclimation of S-anammox.Based on the controllable nitritation,Candidatus Kuenenia stuttgartiensis was the main anammox bacteria in seed sludge for the nitrogen removal from IORW.After 96 days of cultivation,the NLR was 2.94 kg N/?m³·d?,NRR was 2.31 kg N/?m³·d?and TN removal was 78.5%in granules-based N-anammox reactor.To the IORW,ZBAF as a pre-nitritation process combined with completely autotrophic nitrogen removal over nitrite?CANON?that under fewer aeration compare with all the required nitritation directly performed in CANON which can protect the sludge culture and anammox bacteria from high-strength aeration.After 180 days operation,the NRR was 1.22 kg N/?m³·d?by influent NLR with 1.43 kg N/?m³·d?and TN removal was 85.6%.The mixed alkalinity donor?Na₂CO₃ and Na HCO₃?applied in the combined system can save about 14.1-28.2%dosage compare with using Na HCO₃ only.Brocadiaceae was dominant in CANON.In view of startup time,stability and treatment efficiency,partial nitritation-anammox?PN-anammox?was more suitable for IORW than S-anammox and ZBAF-CANON.?3?After PN-anammox treatment,the residual TN was removed via denitrification.When using glucose as carbon source and influent TN lower than 350 mg/L,the C/N ratio between2.5 and 3?HRT=4.2-4.6 h?which about 85%of COD used in nitrogen removal.Low COD can help to avoid SRB convert large amount of sulfate and less sludge or blackened sludge.Glucose was not suitable for IORW treatment when influent TN higher than 350 mg/L.?4?Based on the results of lab-scale,a broaden system?2 t to 10 t?was applied in pilot-scale experiment and provide instance and reference for large-scale experiment.