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Showing papers on "Hydraulic retention time published in 2022"


Journal ArticleDOI
TL;DR: The longterm moving bed biofilm reactor (MBBR) with carrier-attached biofilm was successfully operated for simultaneous removal of nitrogen, phosphorus, and COD at various C/N ratios as mentioned in this paper .

48 citations


Journal ArticleDOI
TL;DR: In this article , the authors summarized the application of MBBR technology for wastewater treatment and discussed the importance of bacterial biofilm and extracellular polymeric substances (EPS), anammox-n-DAMO coupled processes, and carrier surface modifications in MBBR.

35 citations


Journal ArticleDOI
TL;DR: In this paper , the partial denitrification (PD) of nitrate (NO3--N) reduction is combined with an anammox (PD/A) system.
Abstract: The application of anammox technology in low-strength wastewater treatment is still challenging due to unstable nitrite (NO2--N) generation. Partial denitrification (PD) of nitrate (NO3--N) reduction ending with NO2--N provides a promising solution. However, little is known about the feasibility of accelerating nitrogen removal toward the practical application of anammox combined with heterotrophic denitrification. In this work, an ultrafast, highly stable, and impressive nitrogen removal performance was demonstrated in the PD coupling with an anammox (PD/A) system. With a low-strength influent [50 mg/L each of ammonia (NH4+-N) and NO3--N] at a low chemical oxygen demand/NO3--N ratio of 2.2, the hydraulic retention time could be shortened from 16.0 to 1.0 h. Remarkable nitrogen removal rates of 1.28 kg N/(m3 d) and excellent total nitrogen removal efficiency of 94.1% were achieved, far exceeding the applicable capacity for mainstream treatment. Stimulated enzymatic reaction activity of anammox was obtained due to the fast NO2--N jump followed by a famine condition with limited organic carbon utilization. This high-rate PD/A system exhibited efficient renewal of bacteria with a short sludge retention time. The 16S rRNA sequencing unraveled the rapid growth of the genus Thauera, possibly responsible for the incomplete reduction of NO3--N to NO2--N and a decreasing abundance of anammox bacteria. This provides new insights into the practical application of the PD/A process in the energy-efficient treatment of low-strength wastewater with less land occupancy and desirable effluent quality.

35 citations


Journal ArticleDOI
Dong Feng1, Ao Xia1, Yun Huang1, Xianqing Zhu1, Xun Zhu1, Qiang Liao1 
TL;DR: In this paper, carbon cloth was supplemented to investigate the effects on syntrophic degradation of VFA wastewater by increasing organic loading rates (OLRs) under various mixing conditions in CSTRs operating at an HRT of 10 days.

33 citations


Journal ArticleDOI
TL;DR: In this paper , carbon cloth was supplemented to investigate the effects on syntrophic degradation of VFA wastewater by increasing organic loading rates (OLRs) under various mixing conditions in CSTRs operating at an HRT of 10 days.

33 citations


Journal ArticleDOI
TL;DR: In this article , the feasibility of using an algal photo-bioreactor as an integrated algal-bacterial treatment system combined with a dissolved air flotation (DAF) system for the deduction of COD, BOD 5 , TSS, TN and TP from primary treated wastewater (PTW).
Abstract: This research explores the feasibility of using an algal photo-bioreactor as an integrated algal-bacterial treatment system combined with a dissolved air flotation (DAF) system for the deduction of COD, BOD 5 , TSS, TN and TP from primary treated wastewater (PTW). Isolated algae species of Anomoeoneis, Scenedesmus, Anabaena and Spirulina at fixed hydraulic retention time (HRT) of 16 h were used to conduct batch experiments to determine optimum conditions of pH, temperature, light intensity and mixing rate on the removal rates of contaminants. The optimum removal rates were studied at neutral pH, 25 °C, light intensity of 90 μmol m −2 S −1 and 100 rpm mixing rate. A scaled-up pilot plant treatment system was designed, constructed and operated to evaluate the system performance to treat (0.1 L/min) of primary treated wastewater disposed of ZENIN WWTP-Giza, Egypt. The design criteria of the algal photo-bioreactor were acquired from the batch investigations. The plant was operated for 10 continuous days and the analytical analysis was performed twice a day at a fixed time. The DAF system was used to isolate the infiltrated algae from the system for cultivation and reuse purposes. The achieved results revealed the superior COD, BOD 5 , TSS, TN and TP removal percent reached in average 56.4%, 61%, 59.2%, 48.3% and 51.7% at 12 pm and 49.7%, 54.9%, 52.4%, 39% and 40.57% at 12 am, respectively. All data gained from experimental studies demonstrated the efficiency of using algal photo-bioreactor combined with DAF system as an effective wastewater treatment technique. • Algal-bacterial and DAF integrated treatment system is effective for wastewater treatment. • Operating parameters, such as pH, temperature, light intensity and mixing rate were optimized. • A scaled-up pilot plant treatment system was designed for the removal of some contaminants. • COD, BOD 5 , TSS, TN and TP were successfully removed from primary treated wastewater.

31 citations


Journal ArticleDOI
TL;DR: In this article , pH (5.0-6.0) and hydraulic retention time (HRT) were regulated for volatile fatty acids (VFAs) production during glucose fermentation in acidogenic continuous stirred tank reactor (CSTR).

24 citations


Journal ArticleDOI
TL;DR: In this article , two designs of urine-fed microbial fuel cells (MFCs) were tested successfully on a pilot scale as autonomous sanitation systems for decentralised area, and the performance and efficiency were evaluated under different hydraulic retention times (HRT), through chemical oxygen demand measures and polarisation experiments.

23 citations


Journal ArticleDOI
TL;DR: In this article , the authors investigated the effectiveness of extended aeration system (EAS) and rice straw activated carbon-extended aeration systems (RAC-EAS), in the treatment of pulp and paper biorefinery effluent (PPBE).
Abstract: This study investigated the effectiveness of extended aeration system (EAS) and rice straw activated carbon-extended aeration system (RAC-EAS) in the treatment of pulp and paper biorefinery effluent (PPBE). RAC-EAS focused on the efficient utilization of lignocellulosic biomass waste (rice straw) as a biosorbent in the treatment process. The experiment was designed by response surface methodology (RSM) and conducted using a bioreactor that operated at 1–3 days hydraulic retention times (HRT) with PPBE concentrations at 20, 60 and 100%. The bioreactor was fed with real PPBE having initial ammonia-N and total phosphorus (TP) concentrations that varied between 11.74 and 59.02 mg/L and 31–161 mg/L, respectively. Findings from the optimized approach by RSM indicated 84.51% and 91.71% ammonia-N and 77.62% and 84.64% total phosphorus reduction in concentration for EAS and RAC-EAS, respectively, with high nitrification rate observed in both bioreactors. Kinetic model optimization indicated that modified stover models was the best suited and were statistically significant (R2 ≥ 0.98) in the analysis of substrate removal rates for ammonia-N and total phosphorus. Maximum nutrients elimination was attained at 60% PPBE and 48 h HRT. Therefore, the model can be utilized in the design and optimization of EAS and RAC-EAS systems and consequently in the prediction of bioreactor behavior.

23 citations


Journal ArticleDOI
TL;DR: In this article , serial digester systems with two or three biogas reactors were compared with a single reactor, with the aim of improving degree of degradation and methane yield from food waste and assessing adaptation of microbial communities to different reactor steps.
Abstract: Optimization of the biogas generation process is important to achieve efficient degradation and high methane yield, and to reduce methane emissions from the digestate. In this study, serial digester systems with two or three biogas reactors were compared with a single reactor, with the aim of improving degree of degradation and methane yield from food waste and assessing adaptation of microbial communities to different reactor steps. All systems had the same total organic load (2.4 g VS/(L d)) and hydraulic retention time (55 days). Serial systems increased methane yield by >5% compared with the single reactor, with the majority of the methane being obtained from the first-step reactors. Improved protein degradation was also obtained in serial systems, with >20% lower outgoing protein concentration compared with the single reactor and increasing NH4+-N concentration with every reactor step. This resulted in separation of high ammonia (>384 mg NH3-N/L) levels from the main methane production, reducing the risk of methanogen inhibition. Methanosarcina dominated the methanogenic community in all reactors, but increases in the hydrogenotrophic genera Methanoculleus and Methanobacterium were observed at higher ammonia levels. Potential syntrophic acetate-oxidizing bacteria, such as MBA03 and Dethiobacteraceae, followed the same trend as the hydrogenotrophic methanogens. Phylum Bacteroidota family Paludibacteraceae was highly abundant in the first steps and then decreased abruptly, potentially linked to an observed decrease in degradation in the last-step reactors. Nevertheless, the results indicated a trend of increasing relative abundance of the potentially proteolytic genera Proteiniphilum and Fastidiosipila with successive reactor steps.

21 citations


Journal ArticleDOI
TL;DR: In this paper, two types of biocathodes based on carbon cloth were used in the electromethanogenic reactor: with and without retention of biomass on the electrode surface, which led to greater stability of the two-stage anaerobic digestion (AD) process.

Journal ArticleDOI
TL;DR: The co-occurrence analysis revealed the relative abundance of the operational taxonomic units belonging to Anaerolineae and Clostridia was functionally equivalent during the treatment of real domestic sewage, and both the HRT and the stability of the process are important factors for maintaining microbial community structures.
Abstract: Two anaerobic membrane bioreactors (AnMBRs) equipped with different membrane pore size (0.4 or 0.05 µm) were operated at 25˚C and fed with domestic wastewater. The hydraulic retention time (HRT) of the reactors was shortened. The microbial communities of the two AnMBRs were investigated by 16S rRNA gene amplicon sequencing to see the effects of HRT. The predominant Archaea was an aceticlastic methanogen Methanosaeta. The composition of hydrogenotrophic methanogens changed with the HRTs: the population of Methanobacterium was higher for longer HRTs, whereas the population of unclassified Methanoregulaceae was higher for shorter HRTs. The Anaerolineae, Bacteroidia and Clostridia bacteria were dominant in both of the reactors, with a combined relative abundance of over 55%. The relative abundance of Anaerolineae was proportional to the biogas production performance. The change in the population of hydrogenotrophic methanogens or Anaerolineae can be used as an indicator for process monitoring. The sum of the relative abundance of Anaerolineae and Clostridia fluctuated slightly with changes in the HRT in both AnMBRs when the reactor was stably operated. The co-occurrence analysis revealed the relative abundance of the operational taxonomic units belonging to Anaerolineae and Clostridia was functionally equivalent during the treatment of real domestic sewage. A principal coordination analysis revealed that the changes in the microbial community in each reactor were consistent with the change of HRT. In addition, both the HRT and the stability of the process are important factors for maintaining microbial community structures.

Journal ArticleDOI
TL;DR: In this article , two anaerobic membrane bioreactors (AnMBRs) equipped with different membrane pore size (0.4 or 0.05 µm) were operated at 25˚C and fed with domestic wastewater.
Abstract: Two anaerobic membrane bioreactors (AnMBRs) equipped with different membrane pore size (0.4 or 0.05 µm) were operated at 25˚C and fed with domestic wastewater. The hydraulic retention time (HRT) of the reactors was shortened. The microbial communities of the two AnMBRs were investigated by 16S rRNA gene amplicon sequencing to see the effects of HRT. The predominant Archaea was an aceticlastic methanogen Methanosaeta. The composition of hydrogenotrophic methanogens changed with the HRTs: the population of Methanobacterium was higher for longer HRTs, whereas the population of unclassified Methanoregulaceae was higher for shorter HRTs. The Anaerolineae, Bacteroidia and Clostridia bacteria were dominant in both of the reactors, with a combined relative abundance of over 55%. The relative abundance of Anaerolineae was proportional to the biogas production performance. The change in the population of hydrogenotrophic methanogens or Anaerolineae can be used as an indicator for process monitoring. The sum of the relative abundance of Anaerolineae and Clostridia fluctuated slightly with changes in the HRT in both AnMBRs when the reactor was stably operated. The co-occurrence analysis revealed the relative abundance of the operational taxonomic units belonging to Anaerolineae and Clostridia was functionally equivalent during the treatment of real domestic sewage. A principal coordination analysis revealed that the changes in the microbial community in each reactor were consistent with the change of HRT. In addition, both the HRT and the stability of the process are important factors for maintaining microbial community structures.

Journal ArticleDOI
Ivan Novikov1
TL;DR: In this paper , a novel biodegradable PHBV/PLA/rice hulls (PPRH) composite was applied and tested as biofilm attachment carrier and carbon source in two bioreactors for biological denitrification process.

Journal ArticleDOI
TL;DR: In this article, a novel biodegradable PHBV/PLA/rice hulls composite was applied and tested as biofilm attachment carrier and carbon source in two bioreactors for biological denitrification process.

Journal ArticleDOI
TL;DR: In this paper , two types of biocathodes based on carbon cloth were used in the electromethanogenic reactor: with and without retention of biomass on the electrode surface, and they showed a significant increase in the efficiency of the two-stage anaerobic digestion.

Journal ArticleDOI
TL;DR: In this paper , the authors introduced a new method for enhanced biomethane production and pollution control of swine wastewater using anaerobic membrane bioreactor (AnMBR).

Journal ArticleDOI
TL;DR: In this article , a two-stage dynamic membrane bioreactor (DMBR) system for bio-hydrogen and biomethane production from food waste (FW) in mesophilic condition was examined.

Journal ArticleDOI
TL;DR: In this paper, a 300 m3/d hybrid biofilm reactor (HBR) process was developed and operated with a short hydraulic retention time (HRT) of 8 h. The analysis of the bacterial community demonstrated that anammox were enriched in the anoxic zone of the HBR process.
Abstract: The slow initiation of anammox for treating typical domestic wastewater and the relatively high footprint of wastewater treatment infrastructures are major concerns for practical wastewater treatment systems. Herein, a 300 m3/d hybrid biofilm reactor (HBR) process was developed and operated with a short hydraulic retention time (HRT) of 8 h. The analysis of the bacterial community demonstrated that anammox were enriched in the anoxic zone of the HBR process. The percentage abundance of Candidatus Brocadia in the total bacterial community of the anoxic zone increased from 0 at Day 1 to 0.33% at Day 130 and then to 2.89% at Day 213. Based upon the activity of anammox bacteria, the removal of ammonia nitrogen (NH4+-N) in the anoxic zone was approximately 15%. This showed that the nitrogen transformation pathway was enhanced in the HBR system through partial anammox process in the anoxic zone. The final effluent contained 12 mg/L chemical oxygen demand (COD), 0.662 mg/L NH4+-N, 7.2 mg/L total nitrogen (TN), and 6 mg/L SS, indicating the effectiveness of the HBR process for treating real domestic wastewater.

Journal ArticleDOI
TL;DR: In this article, an anoxic packed bed biofilm reactor (AnPBR) inoculated with in-situ biosurfactant-producing bacteria was used for the biodegradation of petroleum wastewater.

Journal ArticleDOI
TL;DR: In this paper, an OxyMem membrane aerated biofilm reactor (MABR) pilot was successfully applied for the treatment of real petrochemical condensate with a total organic carbon (TOC) concentration of approximately 100 mg/L.

Journal ArticleDOI
TL;DR: In this paper , the effects of exogenous strigolactone analog (GR24) on the growth rate, daily productivity and photosynthesis of symbiotes of Chlorella vulgaris (C. vulgaris)-Ganoderma lucidum (G. lucidum)-endophytic bacteria, C. vividis-G.

Journal ArticleDOI
01 Jun 2022-Fuel
TL;DR: In this article , wetland grass (common reed) and cow manure were used as substrates for biogas production during 45-days hydraulic retention reaction, and the results indicated that the strategy was highly effective in increasing bio-methane contents.

Journal ArticleDOI
TL;DR: In this article , a review of the basic features of common constructed wetlands and their different hydrological conditions is presented, followed by the responses of constructed wetlands to the hydraulic parameters hydraulic retention time (HRT), hydraulic loading rate (HLR), and water depth that control the changing water conditions.

Journal ArticleDOI
TL;DR: In this paper, a review of the basic features of common constructed wetlands and their different hydrological conditions is presented, followed by the responses of constructed wetlands to the hydraulic parameters hydraulic retention time (HRT), hydraulic loading rate (HLR), and water depth that control the changing water conditions.

Journal ArticleDOI
TL;DR: In this paper, an SRB acclimatization method using the continuous flow of acid mine drainage (AMD) into bioreactors fed with rice bran was developed to reduce time and economic cost.

Journal ArticleDOI
TL;DR: In this article , an optimized operating parameters in RBC combined with external membrane filtration (RBC-ME), in which the latter acted as a post-treatment step to stabilize the biological performance.
Abstract: A large amount of wastewater is directly discharged into water bodies without treatment, causing surface water contamination. A rotating biological contactor (RBC) is an attached biological wastewater treatment process that offers a low energy footprint. However, its unstable removal efficiency makes it less popular. This study optimized operating parameters in RBC combined with external membrane filtration (RBC-ME), in which the latter acted as a post-treatment step to stabilize the biological performance. Response surface methodology (RSM) was employed to optimize the biological and filtration performance by exploiting three parameters, namely disk rotation, hydraulic retention time (HRT), and sludge retention time (SRT). Results show that the RBC-ME exhibited superior biological treatment capacity and higher effluent quality compared to stand-alone RBC. It attained 87.9 ± 3.2% of chemical oxygen demand, 45.2 ± 0.7% total nitrogen, 97.9 ± 0.1% turbidity, and 98.9 ± 1.1% ammonia removals. The RSM showed a good agreement between the model and the experimental data. The maximum permeability of 144.6 L/m2 h bar could be achieved under the optimum parameters of 36.1 rpm disk rotation, 18 h HRT, and 14.9 d SRT. This work demonstrated the effective use of statistical modeling to enhance RBC-ME system performance to obtain a sustainable and energy-efficient condition.

Journal ArticleDOI
TL;DR: In this article , a combined biological process for OMW treatment in terms of producing for the first time, treated OMW and a valuable microalgae biomass was presented, which involves anaerobic co-digestion (AD), a low cut-off membrane ultra-filtration (UF), and a subsequent Scenedesmus sp. culture.

Journal ArticleDOI
TL;DR: In this article , the effect of different biofilm carriers (conventional AnoxK™ 1 and Z-200 with a pre-defined maximum biofilm thickness) on ADBIOS performance and microbiomics was investigated in duplicate moving bed-biofilm reactors (MBBRs).

Journal ArticleDOI
TL;DR: In this paper , the authors explored the potential of using attached Chlorella sp. for synthetic municipal secondary effluent polishing and biomass production, and investigated the effects of hydraulic retention time (HRT) and biomass harvest interval on microalgal growth, extracellular polymeric substances (EPS) content, harvested biomass composition, and nutrients removal.
Abstract: Advanced nutrients removal from low strength municipal secondary effluent is of urgent need, while microalgae-based approaches can achieve satisfactory effluent polishing without extra chemicals and energy consumption, and the obtained biomass could be processed into value-added products. Conventional suspended systems are either faced with algae-water separation issue, or with the requirement of membrane modules and low scale-up probability. The widely applied attached systems for water remediation such as Algal Turf Scrubbers can resolve the algae-water separation issue, but the biofilm is often dominated by filamentous microalgae, which are of high ash content and low commercial value. Attached systems dominated by selected microalgal strains, however, are mostly fed with high strength wastewater, and the growth and nutrients removal characteristics of these microalgae using low strength effluent is so far unclear. This study explored the potential of using attached Chlorella sp. for synthetic municipal secondary effluent polishing and biomass production, and investigated the effects of hydraulic retention time (HRT) and biomass harvest interval on microalgal growth, extracellular polymeric substances (EPS) content, harvested biomass composition, and nutrients removal. When only HRT was concerned, highest microalgal growth rate (0.77 g/m2/d) and EPS content (80.8 mg/g dry cell weight, DCW) were found at HRT = 2 d, meanwhile total nitrogen and total phosphorus were respectively reduced to 1.2 mg/L and 0.1 mg/L. Attached microalgal growth increased to more than 1.2 g/m2/d at 4 d harvest interval, generating biomass with 27.9–35.2% protein, 20.6–23.4% polysaccharides, and 21.6–26.4% lipid. The biomass EPS content was significantly positively correlated to biomass productivity, reaching highest level (156.8 mg/g DCW) at 4 d harvest interval. Nutrients removal performances, however, were inferior to those without biomass harvest. The mismatch between attached microalgal growth and nutrients removal highlighted the need to balance biomass production and effluent polishing performances when using low strength effluent as culturing medium.