title: Anaerobic digestion of waste biomass from the production of L-cystine in suspended-growth bioreactors.
abstract: Waste biomass from the industrial production of the amino acid L-cystine contains above-average concentrations of organic pollutants and significant concentrations of nitrogen and sulfur. The specific biogas production (SBP) of waste biomass was monitored in parallel suspended-growth laboratory anaerobic bioreactors. After severe inhibition was observed, three different procedures were applied to inhibited reactor sludge to counter-attack the inhibitory effects of sulfides, respectively hydrogen sulfide: micro-aeration, dilution with water and precipitation by ferrous iron cations. The performance of bioreactors was weekly monitored. Organic loading rates (as chemical oxygen demand, COD) ranged from 1.07 to 1.97 g L(-1) d(-1). At the end of the experimentation, SBP averaged 217, 300 and 320 l kg(-1) COD with a methane content of 21%, 52% and 54%; specific sludge production averaged 133, 111 and 400 g total solids kg(-1) COD, and inhibition was 49%, 27% and 25%; for the applied procedures of micro-aeration, dilution and precipitation respectively.
authors.affiliation: Department of Chemical and Environmental Engineering, Faculty of Chemical and Food Technology, Institute of Environmental Engineering, Slovak University of Technology in Bratislava, Radlinského 9, Bratislava 812 37, Slovakia E-mail: juan.fuentes@stuba.sk.
authors.forename: Juan José
authors.initials: JJ
authors.lastname: Chávez-Fuentes
authors.affiliation: Department of Chemical and Environmental Engineering, Faculty of Chemical and Food Technology, Institute of Environmental Engineering, Slovak University of Technology in Bratislava, Radlinského 9, Bratislava 812 37, Slovakia E-mail: juan.fuentes@stuba.sk.
authors.forename: Miroslav
authors.initials: M
authors.lastname: Hutňan
authors.affiliation: Department of Chemical and Environmental Engineering, Faculty of Chemical and Food Technology, Institute of Environmental Engineering, Slovak University of Technology in Bratislava, Radlinského 9, Bratislava 812 37, Slovakia E-mail: juan.fuentes@stuba.sk.
authors.forename: Igor
authors.initials: I
authors.lastname: Bodík
authors.affiliation: Department of Chemical and Environmental Engineering, Faculty of Chemical and Food Technology, Institute of Environmental Engineering, Slovak University of Technology in Bratislava, Radlinského 9, Bratislava 812 37, Slovakia E-mail: juan.fuentes@stuba.sk.
authors.forename: Ronald
authors.initials: R
authors.lastname: Zakhar
authors.affiliation: Department of Chemical and Environmental Engineering, Faculty of Chemical and Food Technology, Institute of Environmental Engineering, Slovak University of Technology in Bratislava, Radlinského 9, Bratislava 812 37, Slovakia E-mail: juan.fuentes@stuba.sk.
authors.forename: Marianna
authors.initials: M
authors.lastname: Czölderová
mesh_terms: D000641:Ammonia / Q000378:metabolism; D000693:Anaerobiosis; D018533:Biomass; D019149:Bioreactors; D003553:Cystine / Q000378:metabolism*; D006862:Hydrogen Sulfide / Q000378:metabolism; D007220:Industrial Waste / Q000032:analysis*; D012037:Refuse Disposal / Q000379:methods*; D012722:Sewage; D014865:Waste Disposal, Fluid / Q000379:methods*
chemical_list: D007220:Industrial Waste; D012722:Sewage; D003553:Cystine; D000641:Ammonia; D006862:Hydrogen Sulfide