• Journal of Animal Environmental Science
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• v.10 no.1
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• pp.29-36
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• 2004

These experiments were conducted to analyze the characteristics of organic compounds and molecular weight distribution according to the treatment steps of purifying system for pig wastewater. The results obtained are summarized as follow. 1. Raw pig wastewater contained 31 kinds of organic compounds such as acetic acid, 2-butanone, hexane, chloroform, propionic acid, butanoic acid etc. 2. After ozone treatment, 13 kinds of organic compounds such as ethene, pentane, 2-methylopropanal, hexane, furan and so on were detected in the wastewater. 3. After $TiO_2$ treatment, 12 kinds of organic compounds such as ethene, hexane, chloroform, 1-decene, silane and so on were detected from the effluent. 4. After both ozone and $TiO_2$ treatment, portion of molecular weight smaller than 500 Daltons and molecular weight between 500 to 1,000 Daltons in the wastewater increased.

• Journal of Korean Society on Water Environment
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• v.24 no.6
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• pp.659-669
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• 2008

Two sets of four parallel activated sludge reactors (ASRs) maintaining an MLSS of 3000 mg/L were operated to investigate the effect of DO, HRTs and bio-contact media (BCM) packing ratios on the removal efficiency of organic matters and nitrogen. Packing ratios of BCM to BCM-ASR systems 1, 2, 3, and 4 were 0% (suspended growth only), 10%, 15% and 20%, respectively. All systems were operated at an HRT of 4 hr, 6 hr, and 8 hr, respectively; DO concentration was maintained 0.5~1.0 mg/L and 1.5~2.0 mg/L for each HRT condition. In terms of TSS, TCODcr and SCODcr removal efficiency, all systems had a similar level of the removal efficiency under varied HRTs, and DO. But organic removal efficiency of systems with BCM was approximately 3~5% higher than systems without BCM at the same HRT and the DO. About the nitrification efficiency, with high DO (1.5~2.0 mg/L), as HRT (4 hr, 6 hr, 8 hr) or BCM packing ratio increased, the slight increment of nitrification efficiency was observed. However, under the low DO (0.5~1.0 mg/L), increase of BCM packing ratio and HRT resulted in large increase of the nitrification efficiency. At the same HRT and BCM packing ratio, the nitrification efficiency increased greatly with up to 15% as DO increased. When the HRT increased from 4hr to 8hr, the denitrification efficiency slightly increased by 5~10% only, under all DO conditions. Systems with BCM had higher denitrification efficiency, ranged 62.7~91.1% than systems without BCM showed 32.1~65.6%. And the increase in BCM packing ratio from 10% to 20% resulted in about 14~16% denitrification efficiency increment. BCM packing ratio showed great effect on the denitrification. The increase of the DO (from 0.5~1.0 mg/L to 1.5~2.0 mg/L) at the same HRT and BCM packing ratio resulted in slight decrease of denitrification efficiency with up to 7% for systems with BCM. But for systems without BCM, the denitrification efficiency decreased with up to 28%. In all system, the denitrification efficiency had more influence on the TN removal efficiency than nitrification efficiency. So, BCM packing ratio (0%, 10%, 15%, 20%) has greater effect on the TN removal than HRT and DO. The TN removal efficiency increased as packing ratio of BCM increased with up to 45%. As a result, the highest TN removal efficiency was observed 73.7% at the condition showed the highest denitrification efficiency that DO of 0.5~1.0 mg/L, an HRT of 8 hr, and 20% of BCM packing ratio was maintained.

• Journal of Korean Society of Water and Wastewater
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• v.21 no.6
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• pp.727-735
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• 2007

The use of water by cities is increasing owing to industrialization, the concentration of population, and the enhancement of the standard of living. Accordingly, the amount of waste water is also increasing, and the degree of pollution of the water system is rising. In order to solve this problem, it is necessary to remove organisms and suspended particles as well as the products of eutrophication such as nitrates and phosphates. This study developed a high-end treatment engineering solution with maximum efficiency and lower costs by researching and developing a advanced treatment engineering solution with the use of Biosorption. As a result, the study conducted a test with a $50m^3/day$ Pilot Scale Plant by developing treatment engineering so that only the secondary treatment satisfies the standard of water quality and which provided optimal treatment efficiency along with convenient maintenance and management. The removal of organisms, which has to be pursued first for realizing nitrification during the test period, was made in such a way that there would be no oxidation by microorganisms in the reactor while preparing oxygen as an inhibitor for the growth of microorganism in the course of moving toward the primary settling pond. The study introduced microorganisms in the endogeneous respiration stage to perform adhesion, absorption, and filtering by bringing them into contact with the inflowing water with the use of a sludge returning from the secondary settling pond. Also a test was conducted to determine how effective the microorganisms are as an inner source of carbon. The HRT(Hydraulic Retention Time) in the nitrification tank (aerobic tank) could be reduced to two hours or below, and the stable treatment efficiency of the process using the organisms absorbed in the NAR reactor as a source of carbon could be proven. Also, given that the anaerobic condition of the pre-treatment tank becomes basic in the area of phosphate discharge, it was found that there was excellent efficiency for the removal of phosphate when the pre-treatment tank induced the discharge of phosphate and the polishing reactor induced the uptake of phosphate. The removal efficiency was shown to be about 94.4% for $BOD_5$. 90.7% for $COD_{Cr}$ 84.3% for $COD_{Mn}$, 96.0% for SS, 77.3% for TN, and 96.0% for TP.

• Membrane Journal
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• v.24 no.1
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• pp.63-68
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• 2014

Manufacturing facility for non-alcoholic drink, the parts of the food industry, disposes wastewater which includes high organic concentration and low nitrogen, phosphorus concentration. For this kind of wastewater, the treatment plant consists mainly of aerobic reactor and chemical coagulation process. And sand-filter or activated carbon process is normally installed further. However, aerobic reactor must have long HRT to treat high concentration of organic contaminant included in this wastewater, so the large site area is required. And settling tank which is normally applied for wastewater treatment facility has some problems such as water quality degradation caused by the sludge spill. To solve these problems, we applied MBR system for the wastewater. And the MBR pilot plant was installed nearby the wastewater treatment facility of W food factory and operated during long term to evaluate treatment efficiency. This plant was operated about 3 months and than the result was 97% of organic removal rate on conditions of flow rate $20m^3/day$, HRT 29 hr, recycle 4Q. However, contaminant removal ratio of bio-reactor decreased and TMP of membrane increased rapidly on more conditions.

• Korean Journal of Microbiology
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• v.45 no.2
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• pp.112-118
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• 2009

Ammonia-oxidizing bacteria (AOB) are chemolithoautotrophs that play a key role in nitrogen removal from advanced wastewater treatment processes. Various AOB species inhabit and their community compositions vary over time in the wastewater treatment bioreactors. In this study, a hypothesis that operational and environmental conditions affect both the community compositions and the diversity of AOB in the bioreactors was proposed. To verify the hypothesis, the clone libraries based on ammonia monooxygenase subunit A were constructed using activated sludge samples from aerobic bioreactors at the Pohang, the Palo Alto, the Nine Springs, and the Marshall wastewater treatment plants (WWTPs). In those bioreactors, AOB within the Nitrosomonas europaea, N. oligotropha, N.-like, and Nitrosospira lineages were commonly found, while AOB within the N. communis, N. marina, and N. cryotolerans lineages were rarely detected in the samples. The AOB community structures were different in the bioreactors: AOB within the N. oligotropha lineage were the major microorganisms in the Pohang, the Palo Alto, and the Marshall WWTPs, while AOB within the N. europaea lineage were dominant in the Nine Springs WWTP. The correlations between the AOB community compositions of the wastewater treatment bioreactors and their operational (HRT, SRT, and MLSS) and environmental conditions (temperature, pH, COD, $NH_3$, and $NO_3{^-}$) were evaluated using a multivariate statistical analysis called the Redundancy Analysis (RDA). As a result, COD and $NO_3{^-}$ concentrations in the bioreactors were the statistically significant variables influencing the AOB community structures in the wastewater treatment bioreactors.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.10
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• pp.992-998
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• 2008

Recently, a new concept for nitrogen removal that is simultaneous nitrification and denitrification(SND) has been studied for wastewater treatment process. The DMR(Daiho Microbic Revolution) process that used in this study consists of two suspended anoxic, anaerobic reactors and an aerobic biofilm reactor. The function of aerobic environment and the intensity of air flow rate(2.0, 1.0, 0.5, 0.4, 0.2 L/min) were studied in the biofilm reactor; also SND and nutrient removal efficiencies were investigated. Experimental results indicated that the change in air flow did not affect COD$_{Cr}$ removal significantly. Thus sustained at 93%. The lower the air flow rate, the higher T-N removal efficiency was attained(i.e.80% at 0.2 L/min). SND efficiency was 62, 65, 72 and 78% corresponding to each air flow rate. T-P removal was sensitive to aeration intensity and removal enhanced from 75% to 96% when the air flow rate was changed from 2.0 to 0.5 L/m; however second release occured in the clarifier at 0.2 L/min. Phosphorus content of activated sludge was 5.0%, as P releases and acetate uptake a ratio of 0.75 mg P/ mg HAc.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.10
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• pp.1021-1027
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• 2008

In this study, biofilm process was introduced for treating nonpoint source pollutants. The ceramic media were provided for biofilm growth in the reactors. The packing ratio of ceramic media was 5% and 15(v/v)%, respectively. Thereafter, the reactors were operated intermittently with the different interevent periods such as 0, 5, 10 and 15 days, respectively. The removal efficiencies of COD and NH$_4{^+}$-N were investigated at the different operating conditions such as media packing ratio, temperature, and interevent period. Additionally, Polymerase chain reaction(PCR)-denaturing gel gradient electrophoresis(DGGE) and INT-dehydrogenase activity(DHA) test were conducted to observe the microbial community and activity in the biofilm. Consequently, the interevent period seemed to have no significant influence on the COD removal efficiency. COD was removed within 6$\sim$8 hours at 25$^{\circ}C$ and about 15 hours at 10$^{\circ}C$. DGGE profiles showed that the initial species of microorganisms were changed from seeded activated sludge into the microorganisms detected in sediments. INT-DHA test also showed that the activities of microorgnaisms were not decreased even in the 15 days of interevent period.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.12
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• pp.1281-1286
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• 2008

Nitrous oxide(N$_2$O) is well known as a greenhouse gas that contributes to the global warming (310 times more per molecule than carbon dioxide) and to the destruction of the ozone layer. The objective of this study is to estimate N$_2$O emission factor using an emission isolation flux chamber from municipal wastewater treatment plants. N$_2$O gas was analysed by GC/ECD with 6 port gas sampling valve. The results of this study were as follows. N$_2$O emission factor of 5-Stage process from Y wastewater treatment plants was lowest as 0.94 g-N$_2$O/kg-TN. And that of other processes were 2.65 g-N$_2$O/kg-TN for Activated sludge process, 9.30 g-N$_2$O/kg-TN for Denipho process, and 26.73 g-N$_2$O/kg-TN for Sequencing Batch Reactor process. We have known that 5-Stage process is most appropriate process to reduce greenhouse for municipal wastewater treatment plants.

• Journal of Korean Society of Water and Wastewater
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• v.23 no.4
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• pp.439-446
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• 2009

This study was performed to evaluate SND(simultaneous nitrification and denitrification)efficiency, nitrogen removal efficiency and filtration function of non-woven fabric by using submerging MBR packed with granular sulfur covered with non-woven fabric filter. Synthetic wastewater was used as influent wastewater. Concentration of $NH_4{^+}-N$ in influent was maintained about 40 mg/L and the experiment was performed in four phases according to the flow rate. Nitrogen loading rate divided four phases ranging from $0.04 kg\;NH_4{^+}-N/m^3-day$ to $0.16 kg\;NH_4{^+}-N/m^3-day$. As a result, the maximum $NH_4{^+}-N$ removal rate was accomplished at $0.142 kg\;NH_4{^+}-N/m^3-day$ in nitrogen loading of $0.147 kg\;NH_4{^+}-N/m^3-day$. Nitrification efficiency was higher than 95% in all phases. $NO_3{^-}-N$ loading rate was adjusted ranging from $0.22 kg\;NO_3{^-}-N/m^3-day$ to $0.89 kg\;NO_3{^-}-N/m^3-day$. The maximum $NO_3{^-}-N$ removal rate was accomplished up to $0.71 kg\;NO_3{^-}-N/m^3-day$ in $NO_3{^-}-N$ loading of $0.89 kg\;NO_3{^-}-N/m^3-day$. The maximum $NO_3{^-}-N$ removal efficiency was 95% in $NO_3{^-}-N$ loading of $0.22 kg\;NO_3{^-}-N/m^3-day$. T-N removal rate was 90% and concentration of T-N in effluent was 3.7 mg/L in T-N loading rate of $0.039 kg\;NO_3{^-}-N/m^3-day$. In this study, TMP in reactor with and without non-woven fabric filter were observed to define fouling of hollow-fiber membrane module. Reaching time to standard washing pressure(22 cm Hg) of two reactors were 29 days with non-woven fabric But the reactor without non-woven fabric reached standard washing pressure only after 4 days. Accordingly, non-woven fabric was demonstrated the superiority as a filtration ability. With high nitrogen removal rate and decreasing of fouling of membrane, MBR packed with granular sulfur covered with non-woven fabric filter submerging in activated sludge aeration tank can be used as an advanced treatment process.

• Korean Journal of Microbiology
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• v.48 no.3
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• pp.200-206
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• 2012

A bacterial strain capable of synthesizing polyhydroxyalkanoates (PHAs) with an unusual pattern of monomer units was isolated from activated sludge using the enrichment culture technique. The organism, identified as Pseudomonas aeruginosa P-5, produced polyesters consisting of 3-hydroxyvalerate and medium-chain-length (MCL) 3-hydroxyalkanoate monomer units when $C_{-odd}$ alkanoic acids such as nonanoic acid and heptanoic acid were fed as the sole carbon source. Solvent fractionation experiments using chloroform and hexane revealed that the 3-hydroxyalkanoate monomer units in these polyesters were copolymerized. The molar concentration of 3-hydroxyvalerate in the polyesters produced were significantly elevated up to 26 mol% by adding 1.0 g/L valeric acid as the cosubstrate. These copolyesters were sticky with low degrees of crystallinity. The PHA synthase genes were cloned, and the deduced amino acid sequences were determined. P. aeruginosa P-5 possessed genes encoding MCL-PHA synthases (PhaC1 and PhaC2) but lacked the short-chain-length PHA synthase gene, suggesting that the MCL-PHA synthases from P. aeruginosa P-5 are uniquely active for polymerizing (R)-3-hydroxyvaleryl-CoA as well as MCL (R)-3-hydroxyacyl-CoAs.