16S rRNA Gene Amplicon Sequencing of Microbiota in Polybutylene Succinate Adipate-Packed Denitrification Reactors Used for Water Treatment of Land-Based Recirculating Aquaculture Systems.

Information on the microbiota in polybutylene succinate adipate (PBSA)-packed denitrification reactors is limited. Here, we provide 439,817 high-quality reads of the 16S rRNA gene sequences of microbiota in PBSA-packed denitrification reactors used for land-based recirculating aquaculture. The predominant microorganisms belonged to the following families: Nocardiaceae, Chitinophagaceae, Xanthobacteraceae, Burkholderiaceae, Rhodocyclaceae, Pseudomonadaceae, Rhodanobacteraceae, and Xanthomonadaceae.

[Stability of Short-cut Nitrification Nitrogen Removal in Digested Piggery Wastewater with an Intermittently Aerated Sequencing Batch Reactor].

Stability of short-cut nitrification nitrogen removal performance was studied in a step-feeding, intermittently aerated sequencing batch reactor (IASBR) at 30°C to treat digested piggery wastewater. Results showed that the nitrogen removal was greatly influenced by the ratio of chemical oxygen demand (COD) to total nitrogen (TN) in the influent. Nitrite nitrogen kept accumulating up to 800 mg · L⁻1 when the influent COD/TN ratio was 0.8 ± 0.2, and the removal rates of TN, ammonium nitrogen and total organic carbon (TOC) were only 18.3% ± 12.2%, 84.2% ± 10.3% and 60.7% ± 10.7%, respectively. By contrast, as the influent COD/ TN ratio was increased to 2.4 ± 0.5, the accumulated concentration of nitrite nitrogen sharply decreased from 800 mg · L⁻¹ to below 10 mg-L⁻¹, and the removal rates of TN, ammonium nitrogen and TOC were increased to over 90%, 95% and 85%, respectively. Gradually shortened hydraulic retention time ( HRT) reveales that the ammonia load is a restricting factor for nitrogen removal. The ammonia load should be controlled at no more than 0.30 kg · (m³ · d) ⁻¹, or else, the removal rates of TN, ammonium and TOC would be greatly decreased. The nitrite accumulation rate over the whole run was 74.6%-97.8% and the TN removal rate in the stable phase was over 90%. With efficient and stable short-cut nitrification-denitrification in a low COD/TN, moreover, and unnecessary for addition of alkaline, IASBR shows great advantage for treating wastewater with high concentration of ammonia while low COD/TN ratio.

[A Comparative Study on Performance of an Intermittent Aeration SBR and a Traditional SBR for Treatment of Digested Piggery Wastewater].

An intermittently aerated sequencing batch reactor (IASBR) and a traditional sequencing batch reactor (SBR) were respectively used for treating digested piggery wastewater, and the pollutant removal performance was studied at different ratios of chemical oxygen demand (COD) to total nitrogen (TN) in the influent and different loading rates. The results showed that the pollutant removal rates in the IASBR were much higher than those in the SBR. Under influent COD/TN of about 2.2 and NH4+-N loading of (0.12±0.04) kg·(m3·d)-1, the removal rates of NH4+-N, TN and TOC in the IASBR were 97.2%±4.4%, 81.5%±7.5% and 88.5%±2.4%, respectively, higher than the corresponding rates of 78.3%±19.6%, 79.8%±4.9% and 86.6%±3.2% in the SBR. As the NH4+-N loading was increased to (0.18±0.02) kg·(m3·d)-1, the removal rates of NH4+-N, TN and TOC in the IASBR were slightly decreased to 92.4%±7.3%, 77.5%±5.3% and 86.4%±2.2%, but still higher than the corresponding values of 78.1%±15.4%, 61.8%±11.2% and 81.8%±5.6% in the SBR. As the NH4+-N loading was remained at (0.20±0.01) kg·(m3·d)-1, but the influent COD/TN ratio was increased to about 3.0, the pollutant removal rates in both IASBR and SBR were increased, compared to those at influent COD/TN ratio of 2.2.The removal rates of NH4+-N, TN and TOC in the IASBR were 99.6%±0.2%, 91.5%±2.9% and 92.0%±0.9%, respectively, higher than the corresponding rates of 90.2%±1.4%, 83.0%±1.9% and 90.2%±0.5% in the SBR. Based on the above, the IASBR was more efficient in TN and ammonium removal and more shocking load resistant, and therefore was more feasible than SBR for treating low COD/TN ratio wastewaters such as the digested piggery wastewater.

[A Comparative Study on Two Membrane Bioreactors for the Treatment of Digested Piggery Wastewater].

With high concentrations of chemical oxygen demand (COD) and ammonium while low ratio of COD to total nitrogen (TN), digested piggery wastewater is difficult to treat using conventional biological methods. In this study, a biofilm membrane bioreactor (BF-MBR) and a traditional type of membrane bioreactor (MBR) were parallel operated to treat digested piggery wastewater, and the pollutant removal performance were compared at influent COD/TN ratios of 1. 0 ± 0. 2 and 2. 3 ± 0. 4, respectively. The results showed that the effluent quality in both reactors was poor and unstable when the influent COD/TN ratio was 1. 0 ± 0. 2. The effluent quality and stability were greatly improved as the influent COD/TN ratio was increased to 2. 3 ± 0. 4. The removal rates of COD and ammonium were respectively 92. 3% ± 2. 4% and 97. 5% ± 4. 1% in BF-MBR, slightly higher than 91. 9% ± 1. 5% and 91. 2% ± 14. 0% in MBR. Benefited from the biofilm, 36. 7% ± 19. 5% of TN and 54. 0% ± 18. 9% of TP were removed by BF-MBR, significantly higher than the respective values of 19. 2% ± 12. 4% and 29. 0% ± 18. 1% by MBR. Moreover, BF-MBR consumed less than 40% of the alkaline chemicals as MBR. BF-MBR was considered more suitable for treatment of digested piggery wastewater due to its better pollutant removal performance and low consumption of alkaline.