Biological Nitrogen Removal Database
A manually curated data resource for microbial nitrogen removal
Biological Nitrogen Removal Database
A manually curated data resource for microbial nitrogen removal
Influent:Fresh seawater
Denitrification system:RAS single-sludge denitrification
Denitrifying reactor:Activated-sludge type reactor
Medium:nan
Culture taken from:Activated sludge
Organism (s) cultured:Gilthead seabream (Sparus Aurata)
Respiration:Anaerobic/aerobic
Electron donor:Volatile fatty acids from Back-Wash Organic Matter (BWOM), intrinsic organic solids
Electron acceptor:Nitrate
Input NO3-N (mg/l):nan
Nitrate removal rate (mg NO3-N/l/h):590.0
Denitrification rate (gNO3-N removed/m3/day):Delete
Microorganisms identified:nan
Molecular tools:nan
Major findings:A ‘single-sludge’ denitrification system, was developed where production of VFA from biosolids and denitrification occur in a single, mixed reactor. Study focused on denitrification in RAS using the intrinsic solids as the energy source. Developed a conceptual stoichiometry-based model of a RAS single-sludge denitrification reactor based on the principles known from activated sludge wastewater treatment modeling.
Authors:Klas et al., 2006
Title:Development of a single-sludge denitrification method for nitrate removal from RAS effluents: Lab-scale results vs. model prediction.
Pubmed link:None
Full research link:Link
Abstract:A lab-scale activated-sludge type reactor was used to induce denitrification by using the organic solid waste of a typical Recirculating Aquaculture System (RAS) as the electron donor (‘Single-sludge denitrification’). The results were compared with the predictions of a stoichiometry-based model. As predicted by the model, reactor's performance was found to be strongly related to the mean solids retention time (SRT) employed. Measured denitrification rates conformed very well to model predictions. High nitrate removal rates ofup to 590 mg N (Lreactord d)?1 were recorded at a relatively low SRT of4 d. Oxygen, that entered the reactor via both atmospheric diffusion and with the stream used to simulate the influent from a fish tank, reduced the amount of organic matter available for denitrification, resulting in lower denitrification rates. This interference was more significant when the system was operated at the longer SRTs. Most of the excess ammonia released to the aqueous phase through ammonification was oxidized (presumably by anammox bacteria) under the prevailing anoxic conditions, resulting in very low effluent TAN concentrations. Phosphate release to the aqueous phase was significantly lower than predicted, suggesting above-typical microbial P assimilation. Reaction kinetics was found to be zero order with respect to nitrate at concentrations ofabove 1.5 to 2.0 mg N L?1. Taken together the findings indicate that intensive single-sludge denitrification for treating RAS effluents is technically feasible, and that the process appears to be a cost-effective solution to reducing both the nutrient and the organic loads generated by intensive fish farms. The main advantages of the method include minimal formation of undesired by-products, small reactor volume and simple control and operation. Furthermore, the process is well described by a conceptual mathematical model, allowing its application as a part of any RAS design.