• 한국물환경학회지
• /
• 제28권5호
• /
• pp.717-722
• /
• 2012

Fluoride can be easily found in semiconductor and display industry. However, there is a lack of research for its effects on the related wastewater treatment. The objective of this study is to evaluate the microbial inhibitory effect by fluoride injection. The research entailed the assessment of removal efficiency of $TCOD_{Cr}$ according to the fluoride concentration and also the Specific Oxygen Uptake Rate (SOUR) was measured. The laboratory scale reactor was prepared and operated with the fluoride concentrations of 0, 10, 50, 100, and 200 mg/L based on concentrations frequently occurring in the wastewater. The results from this study showed that, as the fluoride concentration increase, the Specific Substrate Utilization Rate (SSUR) tend to decrease as expected. Also, the increase in fluoride concentrations resulted in the decrease in SOUR. It is determined that fluoride injection affects the microbial activity. Especially, The addition of above 200 mg/L fluoride into reactor caused rapidly decreased SSUR and SOUR due to the inhibitory effects of fluoride.

• The Korean Journal of Ecology
• /
• 제15권3호
• /
• pp.267-279
• /
• 1992

The relationship between pb, zn, cd, and the microbial biomass and activity were investigated in three public park soils of central and outer london. Variability with distance from the roadside and profile were studied. The heavey metal concentrations were the highest in hampstead heath and hyde park with high trafic density and the lowest in hainault. The highest concentrations of heavy metals were found adjacent to the roadside in the upper parts of the soil profile. Dehydrogenase activity, adenosine tri-phosphate and ergosterol contents used as indices of micrbial biomass and activity, were generally higher in hainadult, and also higher in the upper pats of the soil profile. Simple regression analysis indicated that the microbial biomass and activity were affected significantly by moisture content, water holding capacity, total organic carbon, total nitrogen, and organic mater rather than heavy metal concentration. Highest inputs of nitrogen and carbon were associated with high inputs of heavey metals, all three being derived from vehicle emissions adjacent to the road. The hyde park and hampstead heath microbial populations were able to respond to the c and n input positively by increase in biomass and activity, whereas the hainault populations could not. This rsult suggrsts adaptation in he former to heavy matals, but not in the latter.

• Restorative Dentistry and Endodontics
• /
• 제46권2호
• /
• pp.19.1-19.12
• /
• 2021

Objectives: The purpose of this study was to conduct a systematic review and meta-analysis of in vitro studies regarding the effectiveness of reciprocating and rotary instrumentation on microbial reduction in root canals. Materials and Methods: PubMed, Scopus, Web of Science, the Cochrane Library, and the gray literature were searched through December 2019. Studies comparing the influence of reciprocating and rotary instrumentation on the removal of microorganisms from root canals that quantified the antimicrobial effect were included. Data extraction was completed using a systematic form for data collection. The risk of bias of the studies was evaluated. Standardized mean differences (SMDs) and confidence intervals (CIs) were calculated using a random effects meta-analysis. Results: Seventeen in vitro studies were included in this systematic review, of which 7 provided adequate data for inclusion in the meta-analysis. Both reciprocating and rotary systems were similarly effective in reducing the microbial load in infected root canals (SMD [95% CI], 0.0481 [-0.271, 0.367]). Three studies showed a low risk of bias, whereas most of the studies (82%) presented a medium risk. Conclusions: Although both techniques decrease the microbial content (with reductions of 23.32%-88.47% and 23.33%-89.86% for reciprocating and rotary instrumentation, respectively), they are not able to provide complete disinfection of root canals.

• 한국환경농학회지
• /
• 제27권2호
• /
• pp.139-144
• /
• 2008

고추 재배지 포장에서 고추 품종과 퇴비 시용 수준이 토양 미생물 활성과 다양성에 미치는 효과를 검증하고자 본 시험을 실시하였다. 2007년 4월에 퇴비를 30톤과 60톤 $ha^{-1}$을 살포한 다음, 영고4호와 고은 고추를 5월에 정식하였으며 8월 초에 토양을 채취하였다. 토양 미생물 활성은 탈수소 효소활성과 fluorescein diacetate(FDA) 수화도로 측정하였으며, 토양 미생물 군락은 $EcoPlate^{TM}$와 인지질 지방산을 분석하여 조사하였다. 모든 조사 항목에서 품종간 유의성 있는 차이는 발견되지 않았다. 퇴비 30톤과 60톤 $ha^{-1}$처리는 토양의 pH와 미생물 군락을 변화시켰고, 퇴비 60톤 $ha^{-1}$처리는 토양 유기물과 칼리 함량 증가 그리고 탈수소효소 활성과 FDA 수화도 증가에 효과적이었다. 결론적으로 단기적으로는 토양 화학적, 미생물적 특성에 미치는 영향이 고추 재배 품종보다는 퇴비 등의 유기 개량제의 영향이 크지만, 장기적으로 고추재배 품종 특히 '영고4호'가 일반 재배 품종과는 다른 토양 미생물적 특성을 유도할 수 있는 가능성을 보여 주었다.

• 한국근적외분광분석학회:학술대회논문집
• /
• 한국근적외분광분석학회 2001년도 NIR-2001
• /
• pp.1273-1273
• /
• 2001

The efficiency of the luminal fermentation process influences overall efficiency of luminal production, animal health and reproduction. Ruminant production systems have a significant impact on the global environment, as well. Animal wastes contribute to pollution of the environment as ammonia volatilized to the air and nitrate leached to ground water. Microbial protein synthesis in the rumen satisfies a large proportion of the protein requirements of animals. Quantifying the microbial synthesis is possible by using markers for lumen bacteria and protozoa such as nucleic acids, purine bases, some specific amino acids, or by isotopic $^{15}N,^{32}P,\;and\;^{35}S$ labelled feeds. All those methods require cannulated animals, they are time-consuming and some methods are very expensive as well. Many attempts have been made to find an alternative method for indirect measurement of microbial synthesis in intact animals. The present investigations aimed to assess possibilities of NIRS for prediction of purine nitrogen excretion and ruminal microbial nitrogen synthesis by NIR spectra of urine. Urine samples were collected from 12 growing sheep,6 of them male, and 6- female. The sheep were included in feeding experiment. The ration consisted of sorghum silage and protein supplements -70:30 on dry matter basis. The protein supplements were chosen to differ in protein degradability. The urine samples were collected daily in a vessel containing $60m{\ell}$ 10% sulphuric acid to reduce pH below 3 and diluted with tap water to 4 liters. Samples were stored in plastic bottles and frozen at $-20^{\circ}C$ until chemical and NIRS analysis. The urine samples were analyzed for purine derivates - allantoin, uric acid, xantine and hypoxantine content. Microbial nitrogen synthesis in the lumen was calculated according to Chen and Gomes, 1995. Transmittance urine spectra with sample thickness 1mm were obtained by NIR System 6500 spectrophotometer in the spectral range 1100-2500nm. The calibration was performed using ISI software and PLS regression, respectively. The following statistical results of NIRS calibration for prediction of purine derivatives and microbial protein synthesis were obtained.(Table Omitted). The result of estimation of purine nitrogen excretion and microbial protein synthesis by NIR spectra of urine showed accuracy, adequate for rapid evaluation of microbial protein synthesis for a large number of animals and different diets. The results indicate that the advantages of the NIRS technology can be extended into animal physiological studies. The fast and low cost NIRS analyses could be used with no significant loss of accuracy when microbial protein synthesis in the lumen and the microbial protein flow in the duodenum are to be assessed by NIRS.

• 한국환경복원기술학회지
• /
• 제26권2호
• /
• pp.13-24
• /
• 2023

Sewage sludge has been widely used as an organic fertilizer in agriculture. However, sewage sludge can cause serious malodor problems resulting from the decomposition of organic compounds in anaerobic conditions. The malodor of sewage sludge mainly occurs due to a low carbon to nitrogen ratio (C/N), high moisture, and low temperature, which are ideal conditions for ammonia emissions. Therefore, in this study, we investigated the reduction of the odor-causing ammonia nitrogen (NH₃-N) in sewage sludge by co-application of microbes and methanol (MeOH). The physico-chemical properties of the municipal sewage sludge showed that the odor was mainly caused by a higher NH₃-N content (2932.2 mg L^-1). Supplementation with MeOH (20%) as a carbon source in the sewage sludge significantly reduced the NH₃-N up to 34.2% by increasing C/N ratio. Furthermore, the sewage sludge was treated with the NH₃-N reducing and plant growth promoting (PGP) bacteria Stenotrophomonas rhizophila SRCM 116907. The treatment with S. rhizophila SRCM 116907 significantly increased the seedling vigor index of Lolium perenne (10.3%) and Chrysanthemum burbankii (42.4%). The findings demonstrate that supplementing sewage sludge with methanol significantly reduces ammonia emissions, thereby mitigating malodor problems. Overall, the study highlights the potential of using a microbial and methanol approach to improve the quality of sewage sludge as an organic fertilizer and promote sustainable agriculture.

• 한국식품과학회지
• /
• 제27권1호
• /
• pp.134-140
• /
• 1995

증류식 소주를 안동소주식, 문배주식, 이강주식, 진도홍주식의 전통 방법으로 제조하여 숙성 과정 중 술덧의 pH, 총산, 환원당, 총당, ${\beta}-amylase$, 에탄올, 고형분 등의 성분을 조사하였다. 술덧이 숙성됨에 따라 에탄올은 증가 경향을 보여 발효 16일에 $8.8{\sim}11.2%$까지 증가하였다. 발효 16일 후 술덧의 알콜 함량은 덧술이 첨가된 구가 첨가되지 않은 구에 비하여 높게 나타났다. 총산은 $0.59{\sim}1.10%$까지 증가하였으며 시험구 중 안동소주식 담금 시험구에서 가장 많았다. 총당은 감소경향을 보여 16일에 $6.76{\sim}8.94{\%}$였고 이강주식 담금 시험구가 가장 적었다. 환원당은 담금 직후에는 $6.42{\sim}0.62%$로 안동소주식 담금 시험구가 가장 많았고 발효 16일에는 $0.30{\sim}0.09%$로 감소하였으며 시험구간에 차이가 없는 편이었다. 토고리를 변형하여 제작한 증류장치로 술덧을 증류하여 얻은 소주의 성분을 보면 에탄올 함량은 $35{\sim}40%$로 나타났고, 술덧보다 소주에서 pH가 다소 상승되었고 총산은 감소하였다. 시험구간에 이들 성분의 차이는 거의 없었다. 술덧 중의 당분, 고형분은 소주에서는 검출되지 않았으나 후숙이나 약재 통과의 소주에서는 당분, 고형분이 다소 검출되었다.

• 환경생물
• /
• 제27권4호
• /
• pp.353-362
• /
• 2009

This study attempted to compare the litter decomposition rate of Arundinella hirta and Miscanthus sinensis var. purpurascens which collected from serpentine soil acting potentially toxic concentration of heavy metals and non-serpentine soil by using the microcosm method for 192 days under constant humidity and $23^{\circ}C$. The contents of Ni, Fe, Mg and Cr in the serpentine and nonserpentine soil originated litter showed high differences between them. The litter samples from serpentine site have lower C/N than non-serpentine litter, but the soluble carbohydrate content was shown almost similar between two plant litter. The mass loss rates of leaf litter from serpentine area were slower than those from non-serpentine site. During the experimental period, the remained dry weight of A. hirta and M. sinensis var. purpurascens litter collected from serpentine site were 64.7%, 65.0% of initial dry weight and litter samples from non-serpentine site showed 54.2%, 50.7%, respectively. K and Na were leached rapidly at the initial decomposition periods, but Ca showed immobilization and other metal elements reserved at the decomposing litter for a long time. The decomposing A. hirta litter from non-serpentine soil showed higher values of $CO_2$ evolution, microbial biomass-C, and microbial biomass-N than those in serpentine soil originated litter acting nutrient stresses and exhibited rapid decay rate. The microbial biomass and microbial respiration of decaying litter were positively correlated with litter decomposition rate, and these relationships showed more rapid slope in non-serpentine soil originated litter than that in serpentine soil.

• 환경생물
• /
• 제22권
• /
• pp.38-46
• /
• 2004

다환 방향족 탄화수소(PAHs)에 의한 오염이 미생물군집구조에 미치는 영향을 파악하기 위하여 연안에 가까운 광양만 퇴적토를 대상으로 하여 2000년 3월과 8월 2회에 걸쳐 PAHs 오염도와 말단제한절편 다형성 (T-RFLP)분석방법을 이용하여 미생물 군집구조를 조사하였다. T-RFLP방법으로 조사한 미생물 군집은 계절에 따라 군집이 구분되었으며 월내천입구에 위치한 정점 1에서 3월에 다른 정점과 다른 독특한 군집구조를 형성하였다. 또한 상대적으로 PAHs 오염도가 높은 정점들에서 미생물 다양성도 높은 것으로 나타났다. PAHs 농후배양시료에서의 미생물군집구조 변화와 비교해 볼 때 조사대상지역 퇴적토의 미생물 군집구조는 PAHs의 오염에 부분적으로는 영향을 받지만 군집구조를 결정하는 주된 요인은 온도, 입도, 유기물 함량 등과 같은 환경요인인 것으로 사료된다.

• Asian-Australasian Journal of Animal Sciences
• /
• 제28권4호
• /
• pp.511-518
• /
• 2015

Calliandra calothyrsus preserved in silage is an alternative method for improving the crude protein content of feeds for sustainable ruminant production. The aim of this research was to evaluate the quality of silage which contained different levels of C. calothyrsus by examining the fermentation characteristics and microbial diversity. Silage was made in a completely randomized design consisting of five treatments with three replications i.e.: R0, Pennisetum purpureum 100%; R1, P. purpureum 75%+C. calothyrsus 25%;, R2, P. purpureum 50%+C. calothyrsus 50%; R3, P. purpureum 25%+C. calothyrsus 75%; and R4, C. calothyrsus 100%. All silages were prepared using plastic jar silos (600 g) and incubated at room temperature for 30 days. Silages were analyzed for fermentation characteristics and microbial diversity. Increased levels of C. calothyrsus in silage had a significant effect (p<0.01) on the fermentation characteristics. The microbial diversity index decreased and activity was inhibited with increasing levels of C. calothyrsus. The microbial community indicated that there was a population of Lactobacillus plantarum, L. casei, L. brevis, Lactococcus lactis, Chryseobacterium sp., and uncultured bacteria. The result confirmed that silage with a combination of grass and C. calothyrsus had good fermentation characteristics and microbial communities were dominated by L. plantarum.