• Journal of Korean Society of Environmental Engineers
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• v.31 no.11
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• pp.989-996
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• 2009

In this study, the effects of biofilter media type (three different activated carbons and anthracite), empty bed contact time (EBCT) and temperature on the removal of four aldehyde species (formaldehyde, acetaldehyde, glyoxal and methylglyoxal) in BAC filters were investigated. Experiments were conducted at three water temperature (5, 15 and $25^{\circ}C$) and four EBCTs (5, 10, 15, and 20 min). The experimental results indicated that the coal based BAC retained more bacterial biomass on the surface of the activated carbon than the other BACs, and increasing EBCT or increasing water temperature also increased the four aldehyde species removal in BAC filters. To achieve above 80% of removal efficiency for four aldehyde species in a BAC filter, above 15 min EBCT at $5^{\circ}C$ and 10 min EBCT at above $15^{\circ}C$ were required. The kinetic analysis indicated a first-order reaction rate for the biodegradation of four aldehyde species at various water temperatures. Data obtained from the BAC filters at various temperatures were also used to evaluate pseudo first-order rate constants for four aldehyde species. The half-lives evaluated for formaldehyde, acetaldehyde, glyoxal and methylglyoxal in the coal-based BAC ranging from 0.89 to 3.19 min, from 0.75 to 3.35 min, from 2.16 to 4.72 min and from 1.49 to 3.86 min, respectively, could be used to assist water utilities in designing and operating BAC filters.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.12
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• pp.1255-1261
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• 2008

In this study, The effects of three different biological activated carbon (BAC) materials (each coal, coconut and wood based activated carbons), empty bed contact time (EBCT) and water temperature on the removal of haloacetic acid (HAA) 5 species in BAC filters were investigated. Experiments were conducted at three water temperatures (5, 10 and 20$^{\circ}C$) and four EBCTs (5, 10, 15 and 20 min). The results indicated that coal based BAC retained more attached bacterial biomass on the surface of the activated carbon than the other BAC, increasing EBCT or increasing water temperature increased the HAA 5 species removal in BAC columns. To achieve an HAA removal efficiency 50% or higher in a BAC filter, the authors suggest 10 min EBCT or longer for 5$^{\circ}C$ waters and 5 min EBCT for waters at 10$^{\circ}C$ or higher. The kinetic analysis suggested a first-order reaction model for HAA 5 species removal at various water temperatures (5, 10 and 20$^{\circ}C$). The pseudo-first-order reaction rate constants and half-lives were also calculated for HAA removal at 5, 10 and 20$^{\circ}C$. The pseudo-first-order reaction rate constants and half-lives were also calculated for HAA 5 species removal at 5$\sim$ 20$^{\circ}C$. The half-lives of HAA 5 species ranging from 0.75 to 18.58 min could be used to assist water utilities in designing and operating BAC filters for HAA removal.

• Journal of Korean Society for Atmospheric Environment
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• v.19 no.6
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• pp.689-699
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• 2003

This study was to examine characteristics of treating toluene vapor, which gets to be problematic due to its harmful carcinogenicity and mass generation from various sources, through a biological treatment facility which is environment-friendly and adopts a high-efficient and low-cost clean technology. In order to identify whether Alnus Firma Fruit (AFF) can be used as a media for a bioreactor, its utility and basic operating factors, a study was conducted on pressure drop, supply of nutrient substances and retention time which are operating factors of a biofilter, and eliminating characteristics were compared between AFF and the conventional biological activatedcarbon (BAC) widely used as filter media. In the case of AFF, the initial microbial deposits was 2.3${\times}$10$^{7}$ CFU/g dry AFF, which represents the initial microbial density higher than the case of BAC showing 5.5${\times}$10$^{6}$ CFU/g dry BAC And it took about 2 weeks to acclimate until its eliminating rate got to be increased over 90%. As a result of comparing pressure loss taking place with the lapse of time between BAC and AFF, after 130 days passed at SV 25h$^{-1}$ , BAC showed that its eliminating efficiency had a tendency to drop greatly due to a great pressure loss (0.53\longrightarrow54.7 mm$H_2O$/m) caused by an excess of biomass as accumulated. On the other hand. AFF showed that the pressure drop was 0.53 mm$H_2O$/m, about 2 times as much as the initial pressure loss of 0.4 mm$H_2O$/m, which represents no great change in the pressure loss, and its eliminating efficiency was also shown to be continuously high. Therefore, when AFF was used as a filler for a biological treatment facility, a biological filter enabling improvement of the purifying efficiency to be promoted could be provided, and moreover, the pressure loss was so small that the filler replacement cycle or the back flushing cycle could be extended. So, even in terms of the operating cost, it was identified to be an economical filler When an inorganic material was used as a filler, the biofilters performance acted sensitively on whether nutrient substances were supplied or not. In the case of AFF with low adsorptivity, addition of ethyl-alcohol increased the solubility of toluene, and consequently, biodegradation got to be actively made by microbes, and thus, its eliminating rate could be increased. As the flow velocity and the inflow concentration got to be more increased, its eliminating rate got to be lower, and particularly, an increase in the flow velocity made its eliminating rate drop more greatly than an increase in the concentration.

• Journal of Sensor Science and Technology
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• v.25 no.1
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• pp.13-19
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• 2016

Nowadays, most major automobile manufacturers are very interested, and actively involved, in developing driver alcohol detection system for safety (DADSS) that serves to prevent driving under the influence. DADSS measures the blood alcohol concentration (BAC) from the driver's breath and limits the ignition of the engine of the vehicle if the BAC exceeds the reference value. In this study, to optimize the sensor array of the DADSS, we selected sensors by using three different methods, configured the sensor arrays, and then compared their performance. The Wilks' lambda, stepwise elimination and filter method (using a principal component) were used as the sensor selection methods [2,3]. We compared the performance of the arrays, by using the selectivity and sensitivity as criteria, and Sammon mapping for the analysis of the cluster type of each gas. The sensor array configured by using the stepwise elimination method exhibited the highest sensitivity and selectivity and yielded the best visual result after Sammon mapping.

• Journal of Korean Society of Water and Wastewater
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• v.25 no.4
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• pp.605-610
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• 2011

The objectives of this study are to investigate a bromate behaviour in the processes of advanced water treatment system (AWTS: preozonation, coagulator-settler, rapid sand filter, postozonation, biological activated carbon (BAC) beds) and to investigate the effects of ozonation, pH and ammonia nitrogen on bromate (${BrO^-}_3$) formation. As a result, $BrO_3$ was not detected in the processes of the AWTS without ozonation, while it was detected in a preozonated and postozonated water. For $BrO_3$ formation during June to November, the $BrO_3$ concentration of <9.4${\mu}g/L$ was observed in postozonated water, while it was reduced to about 46% by BAC beds. When applied ozone dosage and ozone contact time for influent with $Br^-$ of <0.3mg/L were 0.5-2.0mg/L.min and 10 min., $BrO_3$ concentration increased with increasing ozone dosage. Longer contact time and lower ozone level also was needed to inhibit the formation of $BrO_3$. At ozone dosage of 1.4 mg/L.min, the formation rate of $BrO_3$ increased with increase of pH value. When $NH_4-N$ concentration increased from 0.1mg/L to 0.4mg/L, $BrO_3$ concentration decreased to about 38%. These results revealed that $BrO_3$ concentration increased with increasing Br level, ozone dosage, and pH value, while it decreased with increase of $NH_4-N$ concentration.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.4
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• pp.857-864
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• 2009

This study aimed at developing the two stage and dual filtration system. It has a sand + activated carbon layer above the underdrain system and a sand layer above the middledrain system for pretreatment. When retrofitting an old filter bed or designing a new one, this technology can substitute the existing sand filter bed without requiring a new site. In order to extend the filtering duration, the upper layer of the filter bed consists of the rapid sand filtration with large particles which pre-treats and removes coarse particles and turbidity matters. The middle layer has biological activated carbon(BAC) and granular activated carbon(GAC) to eliminate dissolved organic matters, disinfection by-products precursors etc. The lower layer consists of the sand filtration for the post filtering mode. In this study, a pilot plant of two stage and dual filtration system was operated for 4 months in the S water treatment plant in Kyounggi-Do. The stability of turbidity was maintained below 1NTU. The TOC, THMFP and HAAFP were removed about 90% by two stage and dual filtration system, which is almost 2 times higher than S WTP. From analysis result of HPC along the depth of activated carbon + sand layer at 2nd stage, microorganism was mostly not detected, however, increment of HPC was shown as it becomes deeper. It indicates that growth of microorganism is occurred at activated carbon layer.

• 한국해양학회지
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• v.30 no.5
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• pp.458-466
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• 1995

To clarify the role of protozooplankton in the microbial food web of Inchon coastal ecosystem, the grazing capacities and growth rates of heterotrophic flagellated (HFL) and ciliates were investigated. We measured the growth rates of bacteria, HFL, autotrophic flagellated (AFL) and ciliates using reverse flow (RF) filter set and obtained the clearance rates and ingestion rates of HFL and dilates by fluorescent labelled bacteria (FLB) method and isolation culture method from natural seawater of Inchon coastal area. The standing crops of bacteria, HFL, AFL and ciliates in this study area were 0.7∼1.5${\times}$10/SUP 6/ cells$.$ml/SUP -1/ 1,680∼2,180 cells$.$ml/SUP -1/, 1,090∼2,180 cells$.$ml, and 3,600∼5,700 cells$.$l/SUP -1/, respectively. The mean growth rates of bacteria, HFL, AFL and ciliates were 0.039 h/SUP -1/, 0.032∼0.033h/SUP -1/, 0.015∼ 0.025h/SUP -1/and 0.021h/SUP -1/, respectively. The growth rates of protozooplankton of Inchon coastal waters were relatively low. Mean grazing rate of HFL, AFL and ciliates were0.039 h/SUP -1/, 0.032∼0.033h/SUP -1/,0.015∼ 0.025h/SUP -1/and 0.021h/SUP -1/, respectively. The growth rates of protozooplankton of Inchon coastal waters were relatively low. Mean grazing rate of HFL on bacteria was 0.055h/SUP -1/. Mean grazing rates of ciliates on HFL was relatively high of 0.057 h/SUP -1/, while the grazing rate of ciliates on AFL was low of 0.019h/SUP -1/. The clearance rates and ingestion rates of HFL on bacteria were 3.6∼61.8nl$.$HFL$.$h/SUP -1/ and 6∼52 BAC. HFL$.$h/SUP -1/ respectively. FLB grazing experiment showed low values, while natural bacteria experiment showed high value meaning high grazing pressure on total bacteria. The clearance rates and ingestion rates of Tintinnopsis sp., dominant ciliates in Inchon coastal waters, were 3.2∼4.6 ul$.$CIL/SUP -1/$.$h/SUP -1/ and 5∼6 cells$.$CIL/SUP -1/$.$h/SUP -1/ respectively, showing higher values in the high tide than low tide. The ingestion rates of ciliates implies that ciliate took up 17∼20% of total nanoflagellates of Inchon coastal waters.

• Korean Journal of Environmental Agriculture
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• v.21 no.3
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• pp.208-215
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• 2002

This study was carried out to evaluate the pollutant removal efficiencies of the advanced drinking water treatment using activated carbon process. for raw water, Nakdong river was used. from the activated carbon adsorption experiment the fellowing results were obtained The efficiency of water treatment enhanced with increase in empty bed contact time. Variation of pH was not detected to the bed depth, but DO content gradually decreased with the bed depth. Removal efficiency of $KMnO_4$ consumption, UV254 absorption, DOC and THMFP also were increased by increasing in the bed depth. Transition of adsorption zone from upper parts of the bed to the lower parts were detected as treatment periods increased. Large portion of DOCs were degraded and removed by the microbes growing on the surface of activated carbons. Cell numbers of microbes were estimated over $1.1\times10^7\;cell/cm^3$ at the depth of 20 cm from the surface 126 days after starting operation. The results shown that the activated carbon Inter was successfully acted as a biofilm filter.