• Environmental Engineering Research
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• v.18 no.4
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• pp.235-239
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• 2013

In the present investigation, the efficiency of Chlorella vulgaris (C. vulgaris) was evaluated for the removal of ammonia-nitrogen from wastewater. Eight different wastewater samples were prepared with varied amounts of $NH_4-N$ concentrations from 15.22 to 205.29 mg/L. Experiments were conducted at pH $7.5{\pm}0.3$, temperature $25^{\circ}C{\pm}1^{\circ}C$, light intensity $100{\mu}E/m^2/s$, and dark-light cycles of 8-16 hr continuously for 8 days. From the results, it was found that $NH_4-N$ was completely removed by C. vulgaris, when the initial concentration was between 5.22-25.24 mg/L. However, only 50% removal was obtained when the $NH_4-N$ concentration was 85.52 mg/L, which further decreased to less than 32% when the $NH_4-N$ concentration exceeded 105.43 mg/L. The further influence of nitrogen on chlorophyll was studied by various $NH_4-N$ concentrations. The maximal value of chlorophyll a (Chl a) content was found to be 19.21 mg/L for 65.79 mg/L $NH_4-N$ concentration, and the maximum specific $NH_4-N$ removal rate of 1.79 mg/mg Chl a/day was recorded at an $NH_4-N$ concentration of 85.52 mg/L. These findings demonstrate that C. vulgaris could potentially be employed for the removal of $NH_4-N$ from wastewater.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.2
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• pp.265-277
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• 2000

Laboratory experiments were conducted to investigate characteristics for removing ammonia-nitrogens by electrolysis methods. A stainless steel plate is used as the cathode and either $IrO_2{\backslash}Ti$ plate serves as the anode. Experiments were conducted to examine the effects of the operating conditions, such as the current density, retention time, electrode gap, $Cl^-/NH_4{^+}-N$ on the $NH_4{^+}-N$ removal efficiency. Possible optimum range for these operating variables are experimentally determined. The $NH_4{^+}-N$ removal efficiencies between plate type anode and net type anode were about same effect, but electrolytic power using net type anode is low than plate type anode. The $Cl^-/NH_4{^+}-N$ ratio was about $20.0kgCl^-/kgNH_4{^+}-N$ when $NH_4{^+}-N$ removal obtained 73 %, $Cl^-/NH_4{^+}-N$ ratio needs $27.6kgCl^-/kgNH_4{^+}-N$ so as to $NH_4{^+}-N$ completely remove. The removal efficiency of $NH_4{^+}-N$ increase with current density, retention time and $Cl^-/NH_4{^+}-N$ ratio, but decreased with increasing electrode gap. The relationship of operating conditions and $NH_4{^+}-N$ removal efficiencies are $$NH_4{^+}-N_{re}(%)=14.5364(Current\;density)^{0.7093}{\times}(HRT)^{1.0060}{\times}(Gap)^{-0.9926}{\times}(Cl^-/NH_4{^+}-N)^{1.0024}$$ With adding COD or/and alkalinity, relationships are $$NH_4{^+}-N_{re}(%)=9.8408(Current\;density)^{0.6232}{\times}(HRT)^{1.0534}$$ There existed a competition between the removals for $NH_4{^+}-N$ and $COD_{Cr}$ during electrolysis, the removal of $NH_4{^+}-N$ was shown to be dominant. $NH_4{^+}-N$ removal was high as addition of glucose and alkalinity.

• Journal of Korean Society on Water Environment
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• v.26 no.4
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• pp.664-672
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• 2010

This study was performed to evaluate the feasibility of industrial by-products such as converter slag, olivine, red mud and fly ash as a seed crystal of struvite crystallization for the removal of highly concentrated $NH_4-N$ and $PO_4-P$. In the kinetic experiments, more than 90% of $NH_4-N$ and $PO_4-P$ was eliminated by struvite crystallization within 30 minutes of reaction time. The pH range in meta-stable region of struvite crystallization was found to be pH 7.0~9.0 under the Mg:N:P=1:1:1 equi-molar condition with 100 mg/L of $NH_4-N$. Total removal efficiencies of $NH_4-N$ and $PO_4-P$ by both struvite precipitation and crystallization were increased with the increase of pH. Removal efficiencies of $NH_4-N$ and $PO_4-P$ were significantly enhanced by struvite crystallization using industrial by-products as a seed crystal compared with those by struvite precipitation without seed crystal. Red mud, converter slag, olivine and fly ash enhanced the removal efficiencies of $NH_4-N$ by 40.9%, 37.7%, 28.4% and 16.4%, respectively. Removal efficiencies of $PO_4-P$ for converter slag, red mud, fly ash, olivine were increased by 3.7 times, 2.6 times, 72.4% and 68.0%, respectively. Converter slag and red mud showed higher feasibility as a seed crystal than others for the removal of highly concentrated $NH_4-N$ and $PO_4-P$. In particular, converter slag might have a high capacity of phosphorus removal.

• Journal of Korean Society on Water Environment
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• v.22 no.3
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• pp.482-491
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• 2006

The anaerobic ammonium oxidation (ANAMMOX) from substrates with various $NO_2-N$ and $NH_4-N$ concentationes, which were generated from piggery waste was accomplished by using anaerobic granular sludge as seeding sludge. As the result of operation, when $NO_2-N/NH_4-N$ ratios of ANAMMOX influent were 0.6~1.5, $NO_2-N/NH_4-N$ removal ratios were exhibited 1.19~2.07 (average 1.63). The higher influent $NO_2-N/NH_4-N$ ratios resulted in higher $NO_2-N/NH_4-N$ removal ratios by ANAMMOX. It means that $NO_2-N$ concentration is very important factor in ANAMMOX. Specific ammonium removal rate was constantly as $0.03{\sim}0.04gNH_4-N/g$ VSS-day at $35^{\circ}C$ while it was $0.01gNH_4-N/g$ VSS-day at $20{\sim}30^{\circ}C$. Thus, in order to reduce the effluent N concentration, either an increase of ANAMMOX reactor HRT or more biomass accumulation at the optimal temperature can be considered.

• Journal of Environmental Health Sciences
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• v.31 no.4 s.85
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• pp.280-286
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• 2005

The purpose of this investigation was to evaluate removal efficiency of $NH_4-N$ using the soil column. Soil, oyster shell and natural zeolite were used as a supporting media of soil column. Removal efficiencies of $NH_4-N$ were $35.9\%,\;41\%\;and\;93.4\%$ for the soil column packed with soil, natural $zeolite(20\%)$ and oyster $shell(20\%)$ at HRT of 72 hours, respectively. The addition of $20\%$ oyster shell to the soil accelerated nitrification in soil column. The influent ammonia nitrogen was mostly converted to nitrate nitrogen in the soil column and little ammonia nitrogen was found in the effluent. When the influent $NH_4-N$ concentration was 200 mg/l, the NIL-N removal was decreased at HRT of 48 hours, while nitrification was significantly increased after mechanical aeration. It was suggested that nitrification from higher $NH_4-N$ concentration was more affected by aeration in soil column process. The number of nitrifiers was approximately in a level of about $10^6\;MPN/g{\cdot}soil$ in the soil column mixed with oyster shell ($20\%$).

• Journal of Korean Society of Environmental Engineers
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• v.32 no.9
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• pp.879-886
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• 2010

This study investigated the removal characteristics of highly concentrated $NH_4$-N and $PO_4$-P by struvite crystallization using converter slag as a seed crystal. The optimal pH range for removal and recovery of $NH_4$-N and $PO_4$-P by struvite crystallization was measured to be 8.0~8.75, in which total removal efficiencies for $NH_4$-N and $PO_4$-P by struvite precipitation and crystallization were 34.3~61.0% and 91.0~96.2%, respectively. The maximum removal efficiencies for $NH_4$-N and $PO_4$-P by struvite crystallization were 29.4% at pH 8.5 and 65.1% at pH 8.0, respectively. The removal efficiency of $NH_4$-N by struvite crystallization decreased with increasing calcium ion concentration. The analysis results of SEM, EDS and XRD exhibited that $NH_4$-N and $PO_4$-P in meta-stable region of struvite crystallization could be eliminated through formation of magnesium ammonia phosphate (MAP) and hydroxyapatite (HAp) on seed crystals by struvite precipitation and crystallization.

• Korean Journal of Microbiology
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• v.39 no.1
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• pp.21-26
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• 2003

Ninety strains of photosynthetic bacteria were isolated from a local stream at Kyonggi-do, Korea and were further screened. Using these isolated strains, experiments were performed under various light and oxygen conditions in order to select strains with high nitrogen $(NH_3-N,\; NO_3^--N)$ removal efficiencies. Results showed that all the strains screened removed $NH_3-N$, the light had no effect on nitrogen removal, and the nitrogen removal rate was higher aerobically than anaerobically. The removal of $NO_3^--N$ was showed up to 35.3% in some specific strains. Results of batch experiments using Rhodocyclus gelatinosus, an isolated strain with a superior removal rate of $NH_3--N$ and $NH_3-N$, under the anaerobic condition, showed that the removal rate of organics and $NH_3-N$ was the highest (98.2 and 89.0%, respectively) at the CODcr (mg/L)/biomass (mg/L) ratio of 0.2, and the $NH_3-N$ concentration did not increase with the decreasing $NH_3-N$ concentration. Experimental results from various C/N ratios confirmed that the effective removal rate (75.8%) of $NH_3-N$ occurred even at the low (5:1) C/N ratio as well as high ratios, and the simulataneous removal of $NO_3^--N$ (96.0%).

• Journal of Aquaculture
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• v.10 no.4
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• pp.435-438
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• 1997

Biological ammonia removal system have been used conventionally for the seawater fish farming. But this process requires long hydraulic retention times and large area. Also it has a trouble of NO3-N accumulation in the system. Therefore, this study was conducted to find out the feasibility of effective nitrogen removal efficiency in the sea water fish farming system by electolysis. As the result, electrolysis system showed a good ammonia and nitrate nitrogen removal and E. coli sterilization efficiencies. Because of the high salinities in the seawater for electron transfer, electrolysis is an effictive water treatment process for seawater fish farming. The relation among ammonia removal efficiency, hydraulic retention time (HRT) and electric wattage (watt) with 10 mm electrod distance isas follow ; log [$NH_4^$+-N(%)]=0.431log(HRT(sec)$\times$Watt)+0.88(r=0.950) And the relation between ammonia removal efficiency and residual chlorine concentration in the seawater is as follow; $$NH_4^+-N(%)=48\cdotlog[Residual\;chlorine(mg/\ell)+28(r=0.892)$$

• 한국생물공학회:학술대회논문집
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• 2005.10a
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• pp.450-455
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• 2005

To treat wastewater efficiently by a one-step process of nitrogen removal, a new strain of $N_2-producing$ bacteria from $NH{_4}{^+}$ under an aerobic condition was isolated and identified. By 16S-rDNA analysis, the isolate was identified as Enterobacter asburiae with 96% similarity. The isolate shows that the capacity of $N_2$ production under an oxic condition was approximately three times higher than that under an anoxic condition. The optimal conditions (pH, temperature and C/N ratio) of the immobilized isolate for $N_2$ production were found to be 7.0, $30^{\circ}C$ and 5, respectively. Under all the optimum reaction conditions, the removal efficiency of $COD_{Cr}$ and TN reached 56.1 and 60.9%, respectively. The removal rates of $COD_{Cr}$ and TN were highest for the first 2.5 hrs (with the removal $COD_{Cr}$ ratios of 32.1), and afterwards the rates decreased as reaction proceeded. For application of the immobilized isolate to a practical process of ammonium removal, a continuous bioreactor system exhibited a satisfactory performance at HRT of 12.1 hr, in which the effluent concentrations of $NH{_4}{^+}-N$ was measured to be 15.4 mg/L with its removal efficiency of 56.0%. The maximum removal rate of $NH{_4}{^+}-N$ reached 1.6 mg $NH{_4}{^+}-N/L/hr$ at HRT of 12.1 hr (with N loading rate of 0.08 $Kg-N/m^3-carrier/d)$. As a result, the application of the immobilized isolate appears a viable alternative to the nitrification-denitrification processes.

• Journal of environmental and Sanitary engineering
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• v.24 no.3
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• pp.7-15
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• 2009

The objective of this study was to investigate difference in nitrogen, organic, phosphorus and $NH_3$-N removal efficiency according to organic loading, comparing M-DEPHANOX process which has two nitrification reactor with M-eBNR process which has one nitrification reactor. As a result of this study, $NH_3$-N removal efficiency of M-DEPHANOX and M-eBNR resulted in average level of 91.8%, 96.9%, respectively. M-DEPHANOX and M-eBNR processes showed high removal efficiency in view of $NH_3$-N removal efficiency. Comparing organic removal efficiency by M-DEPHANOX and M-eBNR processes, the average removal efficiency in terms of TCOD, SCOD was 84.1%, 78.2% and 83.4%, 75.6%. Also, the results that observed about $NH_3$-N removal efficiency regarding organic loading revealed that nitrification reactor of RBC type are little influenced by flowing organic without precipitating at settling tank. Therefore, although inflow characteristics of municipal wastewater changes, M-eBNR process appeared to remove $NH_3$-N reliably.