title: Modeling organic nitrogen conversions in activated sludge bioreactors.
abstract: For biological nutrient removal (BNR) systems designed to maximize nitrogen removal, the effluent total nitrogen (TN) concentration may range from 2.0 to 4.0 g N/m(3) with about 25-50% in the form of organic nitrogen (ON). In this study, current approaches to modeling organic N conversions (separate processes vs. constant contents of organic fractions) were compared. A new conceptual model of ON conversions was developed and combined with Activated Sludge Model No. 2d (ASM2d). The model addresses a new insight into the processes of ammonification, biomass decay and hydrolysis of particulate and colloidal ON (PON and CON, respectively). Three major ON fractions incorporated are defined as dissolved (DON) (<0.1 µm), CON (0.1-1.2 µm) and PON (41.2 µm). Each major fraction was further divided into two sub-fractions - biodegradable and non-biodegradable. Experimental data were collected during field measurements and lab experiments conducted at the ''Wschod'' WWTP (570,000 PE) in Gdansk (Poland). The accurate steady-state predictions of DON and CON profiles were possible by varying ammonification and hydrolysis rates under different electron acceptor conditions. With the same model parameter set, the behaviors of both inorganic N forms (NH4-N, NOX-N) and ON forms (DON, CON) in the batch experiments were predicted. The challenges to accurately simulate and predict effluent ON levels from BNR systems are due to analytical methods of direct ON measurement (replacing TKN) and lack of large enough database (in-process measurements, dynamic variations of the ON concentrations) which can be used to determine parameter value ranges.
authors.affiliation: Faculty of Civil and Environmental Engineering, Gdansk University of Technology, ul. Narutowicza 11/12, Gdansk, Poland. jmakinia@pg.gda.pl
authors.forename: Jacek
authors.initials: J
authors.lastname: Makinia
authors.forename: Krishna
authors.initials: K
authors.lastname: Pagilla
authors.forename: Krzysztof
authors.initials: K
authors.lastname: Czerwionka
authors.forename: H David
authors.initials: HD
authors.lastname: Stensel
mesh_terms: D018533:Biomass; D019149:Bioreactors / Q000382:microbiology; D003102:Colloids / Q000032:analysis*; D004784:Environmental Monitoring; D008962:Models, Theoretical; D009584:Nitrogen / Q000737:chemistry*; D009930:Organic Chemicals / Q000737:chemistry; D052638:Particulate Matter / Q000032:analysis*; D011044:Poland; D012722:Sewage / Q000737:chemistry* / Q000382:microbiology; D014865:Waste Disposal, Fluid; D014874:Water Pollutants, Chemical / Q000737:chemistry; D018508:Water Purification
chemical_list: D003102:Colloids; D009930:Organic Chemicals; D052638:Particulate Matter; D012722:Sewage; D014874:Water Pollutants, Chemical; D009584:Nitrogen