• Journal of environmental and Sanitary engineering
• /
• v.11 no.3
• /
• pp.13-19
• /
• 1996

Packed bed reactor containing immobilized microorganisms which degraded phenol without growth was used to remove phenol from the synthetic wastewater. The effects of temperature, retention time(reactor volume/flow rate) and phenol concentration on the removal efficiency of phenol were investigated. The effect of temperature in the range of 20-30$\circ $C was negligible while retention time and phenol concentration influenced the removal of phenol significantly. When retention time was in the range of 1-1.5 hour, the removal efficiency of phenol was affected not by phenol concentration but by retention time itself while it was influenced by phenol concentration above 1.5 hour of retention time. The beads after 720 hours operation were swelled by 40 % in diameter which could be prevented by crosslinking with glutaraldehyde at the expense of cell activity.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
• /
• 2001.09a
• /
• pp.195-198
• /
• 2001

Bioremediation of hazardous hydrophobic organic compounds, such as polycyclic aromatic hydrocarbons (PAHs), is a major environmental concern due to their toxic and carcinogenic properties. Bue to their low solubility in water, the compounds are microbiologically persistent. This work investigates optimal conditions to enhance the biodegradation of phenanthrene in water and soil-slurry systems. Biodegradation tests were performed with three different types of supplements: glucose as a general carbon source, salicylate as an enzyme inducer, and Triton X-100 as a surfactant. The tests indicate that glucose and Triton X-100 were not very effective to increase biodegradation rate, even though the number of microorganisms are highly increased in the case of glucose addition. Salicylate accelerated biodegradation of phenanthrene, but the addition above optimal concentration inhibited microbial growth. Salicylate is considered to be an attractive alternative for the successful bioremediation of PAH-contaminated soil.

• Journal of the Korea Organic Resources Recycling Association
• /
• v.11 no.4
• /
• pp.66-78
• /
• 2003

The effects of several factors such as heavy metals, living microorganims, high molecular conglomerator in sewage sludge were analysed. And the effects of the sewage sludges which were mixed with other organic waste such as paper mill sludge or night soil sludge upon the feeding rate and biomass of earthworm population were also estimated. The earthworm populations could not survive when newly produced sewage sludges were fed without any pretreatment. The contents of heavy metals were under the levels that could inhibit earthworm's growth. The living microorganisms and the high molecular conglomerator in the sewage sludge had no relations with ecotoxicological effects of sewage sludge upon the earthworm population. Sewage sludge which had been mixed with paper mill sludge and aged for more than 21 days showed no ecotoxicological effects on tiger worm(Eisenia fetida) population. And the feeding rate of earthworm population and the turnover rate of earthworm biomass were higher in those sewage sludges than in the sewage sludges pretreated by other ways.

• Microbiology and Biotechnology Letters
• /
• v.22 no.2
• /
• pp.158-163
• /
• 1994

Microorganisms capale of utilizing linear alkylbenzene sulfonates(LAS) as sole carbon source were isolated from industrial effluent by using LAS agar plates. The isolated strains were identified as Salmonella sp(BC-2) and Escherichia sp.(BC-3) from the results of morphological, cultural and biochemical tests. The optimal condition for the growth and biodegradation of LAS was the initial pH 7.0 and LAS concentration 0.1%. The isolated BC-2 and BC-3 strains harbored plasmid and LAS-degrading activity was lost when the plasmids were cured by mitomycin C. The plasmids were transformed into E. coli and transformants have the LAS-degrading activity. Isolated strains were examined for primary biodegradation rate of LAS in the medium by methylene blueactive substance(MBAS) method. Of these isolates, BC-2 and BC-3 strains degradated LAS upto 60% and high resistant to CdCl$_{2}$ and HgCl$_{2}$. Isolated strains were sensitive to chloramphenicol, kanamycin, rifampicin, streptomycin and tetracycline but resistant to ampicillin and lincomycin.] Its minimal inhibitory concentration(MIC) for ampicillin was more than 1500 $\mu $g/ml.

• Journal of Microbiology
• /
• v.38 no.1
• /
• pp.36-39
• /
• 2000

Toxic hexavalent chromium, Cr(VI), was reduced to a less toxic trivalent chromium form by E. coli ATCC 33456. The suitable electron donor for Cr(VI) reduction was glucose. E. coli ATCC 33456 was more resistant to metal cations than other reported Cr(VI) reducing microorganisms. Cell growth was inhibited by the presence of Cr(VI) in a liquid medium and Cr(VI) reduction accompanied cell growth. With a hydraulic retention time of 20 h, Cr(VI) reducing efficiency was 100% to 84% when Cr(VI) concentration in the influent was in the range of 10 to 40 mg L$\^$-1/. Specific rate of Cr(VI) reduction was 2.41 mg Cr(VI) g DCW$\^$-1/ h$\^$-1/ when 40 mg L$\^$-1/ of Cr(VI) influent was used. This result suggested the potential application of E. coli ATCC 33456 for the detoxification of Cr(VI) in Cr(VI) contaminated wastewater.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.48 no.5
• /
• pp.688-695
• /
• 2015

The objective of this study was to investigate the effects of bio-floc system that is composed of effective microorganisms (EM) on the microbial composition and water qualities in rearing water and the growth of Chinese white shrimp, Fenneropenaeus chinensis. To investigate the microbial composition according to the bio-floc levels, the study was conducted at 100 and 150% of bio-floc after 5 and 10 days in bio-floc system. The results showed that total bacteria count (TBC) and the counts of Latobacillus sp., Bacillus sp. and Rhodobactor sp., were significantly decreased after 5 days in bio-floc system. To assess the growth of F. chinensis according to the concentrations of bio-floc, the study was conducted at the bio-floc concentrations; 0 (control), 60, 80, 100, 120 and 140% of the prepared bio-floc for 90 days. The growth factors such as daily length and weight gain were considerably increased at the concentrations of bio-floc 100, 120, and 140% after 90 days. As water quality indicators, the values of total-N, NH₄⁺-N and PO₄^--P were analyzed, and they were significantly decreased at 120 and 140% of bio-floc, compared to the control. The results demonstrated that combination of EM showed the synergic effect on removing N and P.

• Asian-Australasian Journal of Animal Sciences
• /
• v.24 no.11
• /
• pp.1577-1586
• /
• 2011

This study was carried out to estimate effects of synbiotics containing anaerobic microorganisms and prebiotics on in vitro fermentation characteristics and in situ disappearance rate of fermented total mixed ration (F-TMR). For the in vitro trial, ninety vinyl bags were prepared to analyze temperature, pH, ammonia concentration, microbial growth rate and short chain fatty acid concentration. For the in situ trial, one hundred twenty nylon bags were prepared to analyze dry matter (DM), acid detergent fiber (ADF) and neutral detergent fiber (NDF) disappearance rate. Treatments consisted of a basal diet (US) with prebiotics and probiotics from anaerobic mold (MS), bacteria (BS), yeast (YS) or compound (CS). It was found that temperatures at 14 and 21 days were significantly higher (p<0.05) in the YS and CS than in the others. The pH at 21 days was lower in the CS than in the US. The synbiotic treatments had significantly increased (p<0.05) ammonia concentration at 21 days. The DM disappearance at 72 h was significantly higher (p<0.05) in the MS and CS than in the others. ADF and NDF disappearance rate tended to increase at a rate similar to the DM disappearance rate. Therefore, this study suggests that synbiotics (probiotics with prebiotics) may partially help the quality of fermentation and digestibility of TMR (MS and CS) as fiber disappearance.

• Asian-Australasian Journal of Animal Sciences
• /
• v.16 no.1
• /
• pp.104-115
• /
• 2003

A series of experiments was carried out to determine the possibility for the non-ionic surfactant (NIS) as a feed additive for ruminant animals. The effect of the NIS on (1) the enzyme distribution in the rumen fluids of Hereford bulls, (2) the growth of pure culture of rumen bacteria and (3) rumen anaerobic fungi, (4) the ruminal fermentation characteristics of Korean native cattle (Hanwoo), and (5) the performances of Holstein dairy cows were investigated. When NIS was added to rumen fluid at the level of 0.05 and 0.1% (v/v), the total and specific activities of cell-free enzymes were significantly (p<0.01) increased, but those of cell-bound enzymes were slightly decreased, but not statistically significant. The growth rates of ruminal noncellulolytic species (Ruminobacter amylophilus, Megasphaera elsdenii, Prevotella ruminicola and Selenomonas ruminantium) were significantly (p<0.01) increased by the addition of NIS at both concentrations tested. However, the growth rate of ruminal cellulolytic bacteria (Fibrobacter succinogenes, Ruminococcus albus, Ruminococcus flavefaciens and Butyrivibrio fibrisolvens) were slightly increased or not affected by the NIS. In general, NIS appears to effect Gram-negative bacteria more than Gram-positive bacteria; and non-cellulolytic bacteria more than cellulolytic bacteria. The growth rates of ruminal monocentric fungi (Neocallimastix patriciarum and Piromyces communis) and polycentric fungi (Orpinomyces joyonii and Anaeromyces mucronatus) were also significantly (p<0.01) increased by the addition of NIS at all concentrations tested. When NIS was administrated to the rumen of Hanwoo, Total VFA and ammonia-N concentrations, the microbial cell growth rate, CMCase and xylanase activities in the rumen increased with statistical difference (p<0.01), but NIS administration did not affect at the time of 0 and 9 h post-feeding. Addition of NIS to TMR resulted in increased TMR intake and increased milk production by Holstein cows and decreased body condition scores. The NEFA and corticoid concentrations in the blood were lowered by the addition of NIS. These results indicated that the addition of NIS may greatly stimulate the release of some kinds of enzymes from microbial cells, and stimulate the growth rates of a range of anaerobic ruminal microorganisms, and also stimulate the rumen fermentation characteristics and animal performances. Our data indicates potential uses of the NIS as a feed additive for ruminant animals.

• The Korean Journal of Ecology
• /
• v.12 no.1
• /
• pp.9-20
• /
• 1989

Annual production and decomposition of litter were studied in piuns rigida platation in Mt. Kwan-ak. The peak time of litter production was October-November. The litterfalll at that time was 54% of annual litter production. But the peak time of litterfall of reproductive parts was Junejuly. The peak times of litter production in Alnus hirsuta plantation were June-July, and November. It is thought that difference of seasonal distribution of letterfall between two forest types were assigned to litter falling factors such as temperature and insects. Total amount of letter loss increased according to time. Particulary, the peak time of loss rate was July-August. It was shown that the protein and phosphorus were accumulated in the letter for an experimental period. The amount of crude protein increased to 150% of initial amount. The amount of potassium was increased by August and then decreased rapidly. The contents of crude fat, holocellulose, lignin, and Na were decreased slowly. The loss of holocellulose was the largiest among them. Calcium was in steady state. It was thought that this variation pattern was assigned to leaching of soluble parts by high temperature, rainfall and growth rate of microorganisms.

• Korean Chemical Engineering Research
• /
• v.52 no.5
• /
• pp.581-586
• /
• 2014

Main objects for wastewater treatment operation are to maintain effluent water quality and minimize operation cost. However, the optimal operation is difficult because of the change of influent flow rate and concentrations, the nonlinear dynamics of microbiology growth rate and other environmental factors. Therefore, many wastewater treatment plants are operated for much more redundant oxygen or chemical dosing than the necessary. In this study, the optimal control scheme for dissolved oxygen (DO) is suggested to prevent over-aeration and the reduction of the electric cost in plant operation while maintaining the dissolved oxygen (DO) concentration for the metabolism of microorganisms in oxic reactor. The oxygen uptake rate (OUR) is real-time measured for the identification of influent characterization and the identification of microorganisms' oxygen requirement in oxic reactor. Optimal DO set-point needed for the micro-organism is suggested based on real-time measurement of oxygen uptake of micro-organism and the control of air blower. Therefore, both stable effluent quality and minimization of electric cost are satisfied with a suggested optimal set-point decision system by providing the necessary oxygen supply requirement to the micro-organisms coping with the variations of influent loading.