title: Step-wise temperature decreasing cultivates a biofilm with high nitrogen removal rates at 9°C in short-term anammox biofilm tests.
abstract: The anaerobic ammonium oxidation (anammox) and nitritation-anammox (deammonification) processes are widely used for N-rich wastewater treatment. When deammonification applications move towards low temperature applications (mainstream wastewater has low temperature), temperature effect has to be studied. In current research, in a deammonification moving bed biofilm reactor a maximum total nitrogen removal rate (TNRR) of 1.5 g N m(-2 )d(-1) (0.6 kg N m(-3 )d(-1)) was achieved. Temperature was gradually lowered by 0.5°C per week, and a similar TNRR was sustained at 15°C during biofilm cultivation. Statistical analysis confirmed that a temperature decrease from 20°C down to 15° did not cause instabilities. Instead, TNRR rose and treatment efficiency remained stable at lower temperatures as well. Quantitative polymerase chain reaction analyses showed an increase in Candidatus Brocadia quantities from 5 × 10(3) to 1 × 10(7) anammox gene copies g(-1) total suspended solids (TSS) despite temperature lowered to 15°C. Fluctuations in TNRR were rather related to changes in influent [Formula: see text] concentration. To study the short-term effect of temperature on the TNRR, a series of batch-scale experiments were performed which showed sufficient TNRRs even at 9-15°C (1.24-3.43 mg N g(-1 )TSS h(-1), respectively) with anammox temperature constants (Q10) ranging 1.3-1.6. Experiments showed that a biofilm adapted to 15°C can perform N-removal most sufficiently at temperatures down to 9°C as compared with biofilm adapted to higher temperature. After biomass was adapted to 15°C, the decrease in TNRR in batch tests at 9°C was lower (15-20%) than that for biomass adapted to 17-18°C.
authors.affiliation: a Institute of Chemistry, University of Tartu , Ravila Str 14a, 50414 , Tartu , Estonia.
authors.forename: Ivar
authors.initials: I
authors.lastname: Zekker
authors.affiliation: a Institute of Chemistry, University of Tartu , Ravila Str 14a, 50414 , Tartu , Estonia.
authors.forename: Ergo
authors.initials: E
authors.lastname: Rikmann
authors.affiliation: a Institute of Chemistry, University of Tartu , Ravila Str 14a, 50414 , Tartu , Estonia.
authors.forename: Anni
authors.initials: A
authors.lastname: Mandel
authors.affiliation: a Institute of Chemistry, University of Tartu , Ravila Str 14a, 50414 , Tartu , Estonia.
authors.forename: Kristel
authors.initials: K
authors.lastname: Kroon
authors.affiliation: b Tallinn University of Technology , Ehitajate Rd. 5, 19086 , Tallinn , Estonia.
authors.forename: Andrus
authors.initials: A
authors.lastname: Seiman
authors.affiliation: a Institute of Chemistry, University of Tartu , Ravila Str 14a, 50414 , Tartu , Estonia.
authors.forename: Jana
authors.initials: J
authors.lastname: Mihkelson
authors.affiliation: a Institute of Chemistry, University of Tartu , Ravila Str 14a, 50414 , Tartu , Estonia.
authors.forename: Taavo
authors.initials: T
authors.lastname: Tenno
authors.affiliation: a Institute of Chemistry, University of Tartu , Ravila Str 14a, 50414 , Tartu , Estonia.
authors.forename: Toomas
authors.initials: T
authors.lastname: Tenno
mesh_terms: D064751:Ammonium Compounds / Q000737:chemistry / Q000378:metabolism*; D018441:Biofilms; D019149:Bioreactors; D009584:Nitrogen / Q000032:analysis / Q000302:isolation & purification* / Q000378:metabolism*; D013696:Temperature; D062065:Wastewater / Q000737:chemistry; D018508:Water Purification
chemical_list: D064751:Ammonium Compounds; D009584:Nitrogen; D062065:Wastewater
keywords: Reject water; free ammonia; inorganic carbon; low temperature; nitrite inhibition; redox potential; substrate limitation