Effect of internal recycling ratios on biomass parameters and simultaneous reduction of nitrogen and organic matter in a hybrid treatment system

Nguyen, Dinh Duc; Ngo, Huu Hao; Yoon, Yong Soo

doi:10.1016/j.ecoleng.2015.11.054

Cited by 6 publications

(1 citation statement)

References 20 publications

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“…Internal recirculation (IR) aiming nitrate transport from aerobic to anoxic reactor could have effect on reactor hydraulics since the discharge may vary from two to four times of the plant influent flow. IR is responsible for denitrification, but as a side effect the less concentrated influent could nitrify at increased efficiency due to dilution [7] and improve the oxygen transfer [8]. Due to presence of the IR (and also the returned activated sludge) tracer tests are difficult to interpret; for the determination of longitudinal dispersion empirical formulae are used [9].…”

Section: Introductionmentioning

confidence: 99%

Effect of Internal Recirculation on Reactor Models in Wastewater Treatment

Karches

2018

WIT Transactions on Ecology and the Environment

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Application of mass balance models are widespread in designing wastewater treatment processes, where the emphasis is on the biokinetics and transport processes of the biomass. Reactor hydrodynamics is often idealised applying completely stirred tank reactor (CSTR) or plug flow reactor (PFR) based models. If internal recirculation (IR) is required to be applied for pre-denitrification, these models predict the mass transfer appropriately, but hydrodynamics are not simulated and thus the reactor models remain unchanged. In this research the effect of IR on reactor models was investigated by introducing virtual reactor number applied in the simulation system. GPS-X 6.5 commercial tool was used to perform the calculations and the model was calibrated by field measurement. After the evaluation of the results it could have been seen that in basins with plug flow the application of IR did not modify the reactor model significantly, whereas in CSTRs the virtual reactor numbers shall be modified.

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Section: Introductionmentioning

confidence: 99%

Effect of Internal Recirculation on Reactor Models in Wastewater Treatment

Karches

2018

WIT Transactions on Ecology and the Environment

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Nitrogen removal performance and microbial community of an enhanced multistage A/O biofilm reactor treating low-strength domestic wastewater

Chen

Wang

et al. 2018

Biodegradation

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The low-strength domestic wastewater (LSDW) treatment with low chemical oxygen demand (COD) has drawn extensive attention for the poor total nitrogen (TN) removal performance. In the present study, an enhanced multistage anoxic/oxic (A/O) biofilm reactor was designed to improve the TN removal performance of the LSDW treatment. Efficient nitrifying and denitrifying biofilm carriers were cultivated and then filled into the enhanced biofilm reactor as the sole microbial source. Step-feed strategy and internal recycle were adopted to optimize the substrate distribution and the organics utilization. Key operational parameters were optimized to obtain the best nitrogen and organics removal efficiencies. A hydraulic retention time of 8 h, an influent distribution ratio of 2:1 and an internal recycle ratio of 200% were tested as the optimum parameters. The ammonium, TN and COD removal efficiencies under the optimal operational parameters separately achieved 99.75 ± 0.21, 59.51 ± 1.95 and 85.06 ± 0.79% with an organic loading rate at around 0.36 kg COD/m d. The high-throughput sequencing technology confirmed that nitrifying and denitrifying biofilm could maintain functional bacteria in the system during long-period operation. Proteobacteria and Bacteroidetes were the dominant phyla in all the nitrifying and denitrifying biofilm samples. Nitrosomonadaceae_uncultured and Nitrospira sp. stably existed in nitrifying biofilm as the main nitrifiers, while several heterotrophic genera, such as Thauera sp. and Flavobacterium sp., acted as potential genera responsible for TN removal in denitrifying biofilm. These findings suggested that the enhanced biofilm reactor could be a promising route for the treatment of LSDW with a low COD level.

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