• Journal of Environmental Science International
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• v.30 no.11
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• pp.945-956
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• 2021

In this study, the effects of single and binary heavy metals toxicity on the growth and phosphorus removal ability of Bacillus sp.. known as be a phosphorus-removing microorganism, were quantitatively evaluated. Cd, Cu, Zn, Pb, Ni were used as heavy metals. As a result of analysis of variance of the half of inhibition concentration and half of effective concentration for each single heavy metal treatment group, the inhibitory effect on the growth of Bacillus sp. was Ni < Pb < Zn < Cu < Cd. And the inhibitory effect on phosphorus removal by Bacillus sp. was Ni < Pb < Zn < Cu < Cd. When analyzing the correlation between growth inhibition and phosphorus removal efficiency of a single heavy metal treatment group, a negative correlation was found (R² = 0.815), and a positive correlation was found when the correlation between IC₅₀ and EC₅₀ was analyzed (R² = 0.959). In all binary heavy metal treatment groups, the interaction was an antagonistic effect when evaluated using the additive toxicity index method. This paper is considered to be basic data on the toxic effects of heavy metals when phosphorus is removed using phosphorus removal microorganisms in wastewater.

• Journal of Korean Society of Water and Wastewater
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• v.33 no.3
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• pp.215-224
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• 2019

Recent focus on wastewater treatment includes energy-saving and renewable energy generation for energy-independence of water infrastructures. Aeration and pumping in biological wastewater removal processes account for nearly 30-60% of the total electricity cost in real wastewater treatment plants. In this study, the performance and microbial characteristics were investigated in sequencing batch reactor under typical oxygen and oxygen limited condition. Under typical DO ($7.55{\pm}0.99mg/L$) and low DO ($0.23{\pm}0.08mg/L$) conditions, COD removal was stable over 91 % during SBR operation. Ammonia removal efficiency was reduced from 95.6 % to 89.2 % when DO concentration was dropped sharply. Phosphorus removal efficiency also reached 77% at oxygen-limited condition. The results indicated that removal efficiency both ammonia and phosphorus was influenced by DO condition. Microbial analysis revealed that Proteobacteria and Bacteroidetes at phylum level was dominant in typical DO and low DO conditions and DO concentration did not much affect phylum distribution. Population decrease of genera of nitrifying bacteria(Dokdonella) and Dechloromonas spp. affect removal efficiency of nitrogen and phosphorus at low DO condition.

• Journal of Korean Society on Water Environment
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• v.20 no.1
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• pp.24-31
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• 2004

This study was initiated to evaluate the efficiencies of DEPHANOX and Modified-DEPHANOX, which were devoloped to enhance nitrogen removal efficiency in municipal wastewater treatment. In the results, removal efficiency of organic matters was not affected much by increased loading rate of organic matters which is contained in influent. The nitrogen removal efficiencies according to the loading rate of influent TN was decreased drastically in conditions of over $0.2kg/m^3{\cdot}day$, which is T-N loading rate, and the DEPHANOX process was affected more sensitively than the M-DEPHANOX was. When the temperature was altered from $25^{\circ}C$ to $16^{\circ}C$ at HRT 6hrs, the removal efficiency of ammonia nitrogen was still over 90% and it was concluded that both DEPHANOX and M-DEPHANOX were strong enough to endure temperature variation. Moreover, both processes showed over 90% in ammonia removal efficiencies in over HRT 5hrs, so it was concluded that they were strong in HRT variation. M-DEPHANOX process showed a higher value than DEPHANOX did in T-N removal efficiency to the extent of 4~21 %, which resulted from differency of denitrification rates and the biosorption efficiency of organic matter in both processes. In the condition of HRT less than 4hrs, concentrations of ammonia nitrogen contained in effluents and nitrification reactors, might be sensitively affected by biosorption efficiency of organic matters in first separation tank. In the effect of effluent nitrate concentration in phosphorus removal, the more effluent nitrate concentration was decreased, the more phosphorus removal efficiency was increased. This result is related to the decrease of concentration of effluent nitrate which resulted from nitrification inhibition by decreased HRT.

• Journal of Korean Society of Water and Wastewater
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• v.27 no.1
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• pp.113-120
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• 2013

This study aimed to obtain quantitative data for WWTP operators in phosphorus removal process. This was done by reviewing and comparing phosphorus removal efficiency(%), coagulants dosage(Al/P and $Al_2O_3$(mg/L)), sludge production($kg/m^3$), and operation cost($won/m^3$) of start-up and normal operation data. Phosphorus removal efficiency of all tertiary treatment process was up to 70 ~ 89 % in start-up and normal operation. Average molar ratio(Al/P) was similar as 5 in both operations, but average coagulants dosage (mg/L) of start-up (8.5 mg/L) was higher than normal operation (6.2 mg/L). Average operation cost was higher for start-up ($33.6won/m^3$) than normal operation ($28.4won/m^3$), while electricity cost required for the normal operation ($9.0won/m^3$) was higher by $3.5won/m^3$.

• Journal of Korean Society of Water and Wastewater
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• v.26 no.4
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• pp.579-589
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• 2012

To reduce extensive energy costs of the internal recycling for the purpose of denitrification in the advanced wastewater treatment, a post-treatment process using an electro-coagulation to treat nitrate in the secondary effluents is evaluated in this study. Removals of phosphorus and organics in the secondary effluents by the electro-coagulation were also evaluated to propose an alternative advanced wastewatert treatment process. A series of experiments of the electro-coagulation were carried out with the following 4 different samples: synthetic solution containing nitrate only, synthetic solution containing nitrate as well as phosphorus, secondary effluents from activated sludge cultivated in laboratory, and secondary effluents from real wastewater treatment plants. Removals of nitrate and phosphorus in the synthetic solution were 30 and 97 % respectively, which verified the feasibility of the process. Removals of nitrate, phosphorus and COD in the secondary effluents from the cultivated sludge in laboratory were 49, 90 and 19 % respectively. Removal efficiency of the total nitrogen, nitrrate, phosphorus and COD in the secondary effluent from real wastewater treatment plant were 50, 61, 98 and 80 % respectively. The removal of the total nitrogen was less than the nitrate as expected, which is due to the formation of ammonia nitrogen in the cathode. But the proposed scheme could be an energy saving and alternative process for the advanced wastewater treatment if further studies for the process optimization are carried out.

• Journal of Korean Society on Water Environment
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• v.20 no.5
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• pp.457-465
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• 2004

The objective of this study is to evaluate the possibility to apply the Moving Bed Biofilm Reactor(MBBR) in the activated sludge treatment process with existing aerobic HRT. Optimal operation conditions were assumed according to the analysis of organic matter and nutrients removal efficiencies depending on loading variations. The process was operated under different conditions: RUN I(HRT=7.14hr, $I{\cdot}R=100%$), RUN II(HRT=6.22hr, $I{\cdot}R=100%$), RUN III(HRT=6.22 hr, $I{\cdot}R=150%$), RUN IV(HRT=6.22hr, $I{\cdot}R=200%$), the TBOD removal efficien cies are 88%, 88.5%, 94.6%, 97.6%, respectively. Overall TSS removal efficiency is 90%, and it is increasing in RUN IV. In the case of Nitrogen, the highest removal efficiency of 90% was observed in RUN III and RUN IV, Nitrification and Denitrification rates are 0.013-0.016kg $NH_3-N/kg$ Mv-d and 0.009-0.019kg $NO_3/kg$ Mv-d, respectively. Phosphorus removal efficiencies are 89.6% in RUN I, 91.5% in RUN II, 84.3% in RUN III, and 76.4% in RUN IV. The process under shorter SRT yields better performance in terms of phosphorus removal. It was noticed that to achieve the effluent phosphorus concentration ofless than 1mg/L and removal efficiency higher than 80%, SRT should not be longer than 10 days. Experimental result shows that HRT of 6.22 hours is suitable for this treatment process, and, as a result, the aerobic reactor including moving media and DO depletion tank have a sufficient effect to the process performance.

• Journal of Korean Society of Water and Wastewater
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• v.24 no.4
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• pp.413-423
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• 2010

Eutrophication caused by the excessive supply of phosphorus to water has been considered as one of the most important environmental problems. In this study, the titanium mesostrcture, which was prepared with the template of different surfactant, was tested to confirm the applicability as an adsorbent for phosphorus removal and evaluate the phosphorus removal efficiency. X-ray diffraction analysis, phosphorus adsorption istotherm and kinetic test were performed for the titanium mesostructure, synthesized at various base material/surfactant molar ratio and with different surfactant templates. From the results, we found that mesostructure was synthesized at the base material/surfactant molar ratio of 1/0.25 was most uniformly and clearly formed and thus the adsorption capacity was also maximized.

• Journal of Environmental Science International
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• v.30 no.2
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• pp.161-172
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• 2021

This study was initiated to isolate the microorganisms removing phosphorus (P) from domestic sewage and to investigate the effects of environmental factors on the growth and P removal of the isolated bacteria. Microorganisms isolated from the sewage were identified as Chryseobacterium sp., Stenotrophomonas maltophilia, and Bacillus licheniformis. Among them, Bacillus licheniformis was selected as the P removal microorganism. The environmental factors considered in this study included initial phosphorus concentration, temperature, pH, and carbon source. At initial P concentrations of 10, 20, and 30 mg/L, the P removal efficiencies were 100.0%, 84.0%, and 16.5%, respectively. At 20℃, 30℃, and 40℃, the P removal efficiencies were 0%, 75.8%, and 60.6%, respectively. The removal efficiencies of phosphorus according to pH were 1.6%, 91.7%, and 51.1% at pH 5, pH 7, and pH 9, respectively. Using glucose, acetate, and glucose + acetate as carbon sources yielded P removal efficiencies of 80.9%, 33.6%, and 54.1%, respectively. Therefore, the results from the study demonstrated that the P removal efficiencies of Bacillus licheniformis were the highest when the initial P concentration, temperature, pH, and carbon source were 10 mg/L, 30℃, 7, and glucose, respectively.

• Journal of Korean Society on Water Environment
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• v.22 no.4
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• pp.639-647
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• 2006

The temperature effect at $20^{\circ}$ and $10^{\circ}$ on the nutrient removal efficiency was evaluated in the combined biological nutrient removal system (CBNR) with anaerobic-intermittent aerobic-oxic reactors. The test was conducted under the conditions of various ratios of intermittent aeration time and distribution of influent raw water to CBNR. The removal efficiencies of organics, nitrogen and phosphorus were a little bit better at $20^{\circ}$ than at $10^{\circ}$. However the large difference of temperature effect on the nutrient removal efficiency between $20^{\circ}$ and $10^{\circ}$ was not appeared because of highly sustained MLSS concentrations in the reactors and controlled intermittent aeration time. In the removal of phosphorus, Mode III (50/70 min in aeration on/off time, 3 times of intermittent aeration) showed more effective compared with short aeration time of Mode IV. In case of N, P removal, the denitrification rate was lower in Mode A with splitted inflow into anaerobic and intermittent aeration basins than in Mode B with sole inflow into anaerobic basin.

• Korean Journal of Soil Science and Fertilizer
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• v.51 no.1
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• pp.35-49
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• 2018

This study was initiated to quantitatively evaluate the effects of five heavy metals (Cd, Cu, Zn, Pb, and Ni) on growth and P removal efficiencies of Pseudomonastaeanensis, known as the phosphorus accumulating microorganism. The heavy metals were added individually and with the binary mixture to the batch culturing system of Pseudomonastaeanensis. $IC_{50}$ and $EC_{50}$ were used to quantitatively evaluate their effects on the growth and phosphorus removal efficiency of Pseudomonas taeanensis in those treatments. Additionally, additive index value method was used to evaluate the interactive effects of heavy metals for Pseudomonas taeanensis in this study. As those heavy metals were singly added to Pseudomonastaeanensis, the greatest inhibitory effect on its growth and P removal efficiency was observed in Cd, whereas, the smallest effect was found in Ni. As the concentrations of all heavy metals added were gradually increased, its growth and P removal efficiency was correspondingly decreased. Specifically, $IC_{50}$ of Pseudomonas taeanensis for Cd, Cu, Zn, Pb, and Ni were $0.44mg\;L^{-1}$, $5.12mg\;L^{-1}$, $7.46mg\;L^{-1}$, $8.37mg\;L^{-1}$ and $14.56mg\;L^{-1}$, respectively. The P removal efficiency of Pseudomonas taeanensis was 81.1%. $EC_{50}$ values of Pseudomonas taeanensis for Cd, Cu, Zn, Pb, and Ni were $0.44mg\;L^{-1}$, $4.08mg\;L^{-1}$, $7.17mg\;L^{-1}$, $8.90mg\;L^{-1}$ and $11.26mg\;L^{-1}$, respectively. In the binary treatments of heavy metals, the lowest $IC_{50}$ and $EC_{50}$ were found in the Cd + Cu treatment, whereas, the highest $IC_{50}$ and $EC_{50}$ were found in the Zn + Pb and Pb + Ni treatments, respectively. Most of the interactive effects for the binary mixture treatments of heavy metals were antagonistic. Based on the results obtained from this study, it appears that they could provide the basic information about the toxic effects of the respective individual and binary treatments of heavy metals on the growth and P removal efficiency of other phosphorus accumulating organisms.