18 / 2023-12-18 00:13:05

Evaluating Utilization Rate of Organic and Nitrogenated Substrates by Microorganisms in Sequencing Batch Reactor Treating Tannery Wastewater

organic substrate utilization rate,sequencing batch reactor,nitrogenated substrate utilization rate

In this article, the utilization rate of organic and nitrogenous substrates contained in tannery wastewater by a sequential batch reactor is evaluated. Two factorial experimental designs (FEDs) were implemented. FED1 (22) used granular biomass, the aeration sequence (oxic, anaerobic-oxic) and cycle duration (6 and 24 h). FED2 (4 x 3) included suspended biomass, reaction phases (anoxic I, oxic, anoxic II (CND: conventional nitrification-denitrification) and (SND: simultaneous nitrification-denitrification), filling time (fast, slow and in stages). The substrates examined were chemical oxygen demand (COD), ammonium (NH4+-N) and total nitrogen Kjeldahl (TKN). The utilization rates were COD (-100 and -200 mg L^-1 h^-1) (FED1) and (-48 and -75 mg L^-1 h^-1) (FED2), being 1.5 to 2 times higher in FED1 than FED2. In TKN (-5 mg L^-1 h^-1), and NH4+-N (-30 mg L^-1 h^-1), they were significant in the anoxic I and oxic phases. The tannery wastewater was treated with granular biomass in the SBR biological process under two types of sequences: Oxic and anaerobic-oxic obtaining similar removal in COD, requiring cycle durations of 24 h to achieve stabilization in the COD removal rate. The COD removal was increased in two times for cycle durations increased from 6 h to 24 h. COD removal is influenced by inhibitory and recalcitrant matter contained in the tannery wastewater for the biological activity in SBR operation, lack of an essential nutrient or electron acceptor, toxic concentrations of the compound to be degraded producing enzyme inactivation, reaching efficiency values that varied between 30 and 40 %. For the granular biomass performance, the trend of COD removal rate in the oxic system was a slightly change, taking a value around -100 to -295 mg L^-1 h^-1 compared to the anoxic-oxic system, which showed values from -46 mg L^-1 h^-1 to -53 mg L^-1 h^-1. The TKN and NH4+-N removal rates were significant in the first anoxic phase and oxic phases, respectively. This result suggests that simultaneous nitrification-denitrification is taking place in the first anoxic phase and the microorganisms are carrying out a conventional reaction of nitrification in the oxic stage. For the removal of organic and nitrogenated substrates from the tannery wastewater, the suitable treatment in SBR would be composed by a sequential biological mixed phase (anoxic-oxic) using granular biomass.