• Journal of Environmental Science International
• /
• v.20 no.1
• /
• pp.35-47
• /
• 2011

The effect of the variation of aeration time on the removal of organics, nitrogen and phosphorus using synthetic wastewater was investigated in sequencing batch reactors (SBRs) which included DNPAOs and DNGAOs. The cycling times in four SBRs were adjusted to 12 hours and then included different aerobic times as 1 hr, 2.5 hr, 4 hr and 5.5 hr, respectively. Four SBR systems have been operated and investigated for over 40 days. Average TOC removal efficiencies were about 71 % in all SBRs. The $NH_4^+$-N removal efficiency was increased as the increase of aeration time. After changing aeration time, the total nitrogen removal efficiencies of SBRs were shown as 35 %, 85 %, 75 % and 65 %, respectively. Higher phosphorus release and uptake were occurred as the decrease of the aeration time. After all, the overall phosphorus removal efficiency decreased and the deterioration of phosphorus removal was occurred when aeration time was over 4 hr. Denitrification in aerobic conditions was observed, which showed the presence of DNPAOs and DNGAOs. In batch experiments, PAOs were shown as the most important microorganisms for the phosphorus removal in this experiment, and the role of DNGAOs was higher than that of DNAPOs for the nitrogen removal.

• Membrane and Water Treatment
• /
• v.15 no.1
• /
• pp.1-9
• /
• 2024

Biological nutrient removal is gaining increasing attention in wastewater treatment plants; however, it is adversely affected by low temperatures. This study examined temperature effects on nutrient removal and morphological stability of the granular and denitrifying phosphorus accumulating organisms (PAO and DPAO, respectively) using sequencing batch reactors (SBRs) at 5, 10, and 20 ℃. Lab-scale SBRs were continuously operated using anaerobic-anoxic and anaerobic-oxic cycles to develop the PAO and DPAO granules for 230 d. Sludge granulation in the two SBRs was observed after approximately 200 d. The average removal efficiency of soluble chemical oxygen demand (SCOD) and PO₄^3--P remained >90% throughout, even when the temperature dropped to 5 ℃. The average removal efficiency of NO₃^--N remained >80% consistently in DPAO SBR. However, nitrification drastically decreased at 10 ℃. Hence, the removal efficiency of NH₄⁺-N was decreased from 99.1% to 54.5% in PAO SBR. Owing to the increased oxygen penetration depth at low temperatures, the influence on nitrification rates was limited. The granule in DPAO and PAO SBR was observed to be unstable and disintegrated at 10 ℃. In conclusion, morphological characteristics showed that changed conversion rates at low temperatures in aerobic granular sludge altered both nutrient removal efficiencies and granule formation.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
• /
• 2002.10b
• /
• pp.189-190
• /
• 2002

Rolling-sliding friction was investigated for three SBR (styrene-butadiene rubber) specimens including silica-filled, HAF carbon black-filled, and SAF carbon black-filled SBR. When a rubber wheel was rolled against a glass disk, the coefficient of friction varied with the slip ratios. The coefficient of friction for the silica-tilled SBR showed the highest value of the rubber specimens examined under various slip ratios. The contact areas of silica-filled SBR were larger than those of the carbon black-filled SBRs, as indicated the modulus of the silica-filled SBR showing the lowest value. The contact area during rolling-sliding friction was always smaller than those during the static contact. The friction force at the unit contact area for the silica-filled SBR under braking and driving was higher than those of carbon black-filled SBRs.

• Journal of Environmental Science International
• /
• v.20 no.1
• /
• pp.49-59
• /
• 2011

The effect of the variation of aeration time on the microorganisms was investigated in sequencing batch reactor (SBRs). The cycling time in four SBRs was adjusted to 12 hours and then included different aerobic times as 1 hr, 2.5 hr, 4 hr and 5.5 hr, respectively. Four SBR systems have been operated and investigated for over 40 days. As the increase of aeration time, the consumption of glycogen within sludge at the 1st non-aeration time a little bit was increased and the production of glycogen at the aeration time was increased. Also, the produced PHB amounts and PHB production rate at the 1st non-aeration time were increased as the decrease of aeration time, which showed the activation of the phosphorus removal. The ratios of nitrifying microorganisms' number and GAOs to the total microorganisms' number in SBRs was decreased as the decrease of the aeration time, however, the PAOs ratio was almost constant irrespective of the variation of aeration time.

• Journal of Korean Society on Water Environment
• /
• v.33 no.3
• /
• pp.302-310
• /
• 2017

The morphological characteristics of granules developing in anaerobic-anoxic (An-Ax) and anaerobic-aerobic (An-Ox) sequencing batch reactors (SBRs) were examined. The granules developed in the both SBRs after 200 days of laboratory operation. The average diameters of the granules were $2.2{\pm}1.7mm$ in the An-Ax SBR and $0.4{\pm}0.3mm$ in the An-Ox SBR. To determine the possible factors affecting morphology of granules a comparative analysis of various operating conditions from reference data indicated that the availability and type of electron acceptors is a key factor determining the granulation process and granular morphology.

• Journal of Environmental Science International
• /
• v.6 no.6
• /
• pp.697-709
• /
• 1997

Sequencing Batch Reactor(SBR) experiments for organics and nutrients removal have been conducted to find an optimum anaerobic/anoxic/aerobic cycling time and evaluate the applicability of oxidation-reduction potential(ORP) as a process control parameter. In this study, a 61 bench-scale plant was used and fed with night-soil wastewater in K city which contained TCODcr : 10, 680 mg/l, TBm : 6, 893 mg/l, $NH_4^+-N$ : 1, 609 mg/l, $PO_4^{3-}-P$ : 602 mg/l on average. The cycling time In SBRs was adjusted at 12 hours and 24 hours, and then certainly included anaerobic, aerobic and inoxic conditions. Also, for each cycling time, we performed 3 series of experiment simultaneously which was set up 10 days, 20 days and 30 days as SRT From the experimental results, the optimum cycling time for biological nutrient removal with nlght-soil wastewater was respctively 3hrs, 5hrs, 3hrs(anaerobic-aerobic-anoxic), Nitrogen removal efficiency was 77.9%, 77.9%, 81.7% for each SRT, respectively. When external carbon source was fed in the anoxic phase, ORP-bending point indicating nitrate break point appeared clearly and nitrogen removal efficiency increased as 96.5%, 97.1%, 98.9%. Phosphate removal efficiency was 59.8%, 64.571, 68.6% for each SRT. Also, we finded the applicability of ORP as a process control parameter in SBRs.

• Journal of Environmental Science International
• /
• v.6 no.5
• /
• pp.521-529
• /
• 1997

In the study, we Investigated the behavior and removal efficiency of organics, nitrogen. phosphorus with operating conditions in SBRs. Substrate used was synthetic wastewater in which the ratio of $COD_{cr}$. : N : P was 100 : 12 : 2. The cycling the in SBRs was adjusted at 6 hours and 8 hours, and then certainly Included anaerobic and aerobic conditions. Also, for each cycling time. we performed 2 series of experiment simultaneously which was set up 10 days and 20 days as SRT. The removal efficiency of $COD_{cr}$. was over 97% in all operating conditions. In the 6 hours cycling time, the removal efficiency of $PO_4^{3-}-P$ reached almost 100% in steady state. And then we could observe a typical phonemena of phosphorus release and uptake, and the removal efficiency of N was 67%, Residual N source was almost TKN and most of the rest remained as $NO_2-N$. Also the difference in both SRTs was not observed practically. In the 8 hours cycling time, dissolution of sludge appeared. and, $PO_4^{3-}-P was not nearly removed but nitrogen was removed up to 75%, And the residual nitrogen was accumulated as $NO_2^--N$.

• Environmental Engineering Research
• /
• v.24 no.1
• /
• pp.107-116
• /
• 2019

Nitrogen removal, nitrous oxide ($N_2O$) emission and microbial community in sequencing batch and continuous-flow intermittent aeration processes were investigated. Two sequencing batch reactors (SBRs) and two continuous-flow multiple anoxic and aerobic reactors (CMRs) were operated under high dissolved oxygen (DO) (SBR-H and CMR-H) and low DO (SBR-L and CMR-L) concentrations, respectively. Nitrogen removal was enhanced under CMR and low DO conditions (CMR-L). The highest total inorganic nitrogen removal efficiency of 91.5% was achieved. Higher nitrifying and denitrifying activities in SBRs were observed. CMRs possessed higher $N_2O$ emission factors during nitrification in the presence of organics, with the highest $N_2O$ emission factor of 60.7% in CMR-L. SBR and low DO conditions promoted $N_2O$ emission during denitrification. CMR systems had higher microbial diversity. Candidatus Accumulibacter, Nitrosomonadaceae and putative denitrifiers ($N_2O$ reducers and producers) were responsible for $N_2O$ emission.

• Elastomers and Composites
• /
• v.59 no.1
• /
• pp.17-21
• /
• 2024

Solution styrene-butadiene rubber (S-SBR) is used to improve the wet grip and rolling resistance properties of tire treads. As blending of SBRs can improve the physical properties of tire treads, we investigated the effects of SBR type and blending ratio on the physical properties. Twelve SBR/SBR biblend composites were prepared using four SBRs with different microstructures. The glass transition temperature (T_g), tanδ at 0℃ (wet grip predictor), and tanδ at 60℃ (rolling resistance predictor) were obtained from dynamic mechanical analysis, and were compared to the expected values obtained from the results of single SBR samples. Most of the SBR/SBR biblend composites exhibited crosslink densities lower than the expected values. The tanδ values at 0℃ and 60℃ of the SBR/SBR blend composites deviated from the expected values, with many of the deviations being disadvantageous. Of the twelve composites, six samples had higher 0℃ tanδ values than the corresponding expected values, and four exhibited superior wet grip properties to those of the SBR single samples. In addition, two of the twelve samples exhibited improved rolling resistance properties as compared with the single SBR samples. Finally, four samples exhibited lower T_g values than expected, and the T_g of one composite was lower than those of the single SBR samples.

• Elastomers and Composites
• /
• v.44 no.3
• /
• pp.232-243
• /
• 2009

The specialized and diversified synthetic and compounding technologies are used to meet the requirements for the advanced high performance tire tread materials with better balance of fuel economy(rolling resistance), safety(wet traction) and wear resistance. These techniques involve the methodology for the improvement of chemical and physical interaction between filler and the rubber matrix using coupling agents as well as a variety of chemically-modified solution SBRs. The research trends about the high performance functional SBRs and coupling agents which can interact with the surface of fillers and their working mechanism were investigated in the conventional carbon black-filled rubber and silica-filled SBR systems developed recently as "green tire".