최의소 , 박종복 Eui So Choi , Jong Bok Park

DOI: Vol.10(No.2) 75-81, 1994

This study was conducted to chracterize the nutrient removal aspects in an air lifted biofilm reactor using waste plastic as media. The air-lift biofilm reactor was operated with continuous and cyclic aeration at various hydraulic retention times and different temperatures. The media for the biofilm development was the waste plastic containers which has surface area and the void space of the plastic media used in this study were 76 ㎡/㎥ and 93%, respectively. Domestic sewage was introduced into the reactor, and BOD, TKN, and TP concentrations were 70 to 140, 14 to 22, and 3 to 4㎎/ℓ, respectively. The nitrogen removal efficiencies and nitrogen content of the sludge were 28.35 and 7%, respectively, with continuous aeration, and 50% and 9% with cyclic aeration. The nitrification and the denitrification rates were 4.3㎎ N/g·MLVSS·hr and 1.2㎎ NO₃-N/g·MLVSS·hr, respectively, at 26℃. It was estimated that sludge production was 0.19 to 0.27㎏ VSS/㎏ BODrm. Air backwashing seems to require every 60 days at the organic loading rate of 0.15 to 0.218 ㎏ BOD/㎥·d. The operating mean MLSS concentration was estimated to 4,200 ㎎/ℓ and SRT 47 to 75 days.

최찬식 , 김동한 , 정태학 Chan Sik Choi , Dong Han Kim , Tai Hak Chung

DOI: Vol.10(No.2) 82-89, 1994

Laboratory experiment was performed to investigate the effects of nitrate on the removal of organics, nitrogen, and phosphorus using a sequencing batch reactor(SBR). The nitrate nitrogen of 10㎎/ℓ, 20㎎/ℓ, 30㎎/ℓ, and 50㎎/ℓ was fed to influent. During studies the fixed mode of operation consisted of 2 hours of fill, 4 hours of reaction, and 2 hours of settling and drawing period. Anoxic condition was provided for 1.5 hours of the fill period and 1.75 hours of the reaction period for efficient denitrification and phosphorus release. The temperature was set at 20℃ and the influent COD was maintained at 350㎎/ℓ. As the nitrate nitrogen concentration of influent increased, the removal of organic substance, ammonia, phosphorus decreased, but the removal of nitrogen increased. Especially, the nitrate nitrogen influenced the removal of phosphorus by inhibiting the release of phosphorus. The removal efficiency of control reactor was 92%, but it was reduced to 58% in case of 50㎎ NO₃-N/ℓ added.

서정범 , 윤조희 , 임연택 , 홍정선 , 류재근 , 서윤수 J . B . Seo , C . H . Yoon , Y . T . Rim , J . S . Hong , J . K . Ryu , Y . S . Suh

DOI: Vol.10(No.2) 90-95, 1994

Membrane technology has been emerging as one of essential processes for wastewater treatment. Ultrafiltration(UF) can seperate the biomass from Activated sludge(AS) process and maintain higher biomass concentration in the process. This combination of AS and UF can have many advantages such as better effluent quality and system stability over the conventional process. In this experiment, UF combined to AS was used to investigate the effects of various operational factors on the performance of the system and the change of microorganism groups. Following conclusions were obtained. 1) Good effluent quality was obtained at high organic loading rate and good stability was maintained throughout the experiment. 2) The flux was stable with the high value when organic loading rate was maintained below 0.8㎏BOD/㎥·d at 1m/sec surface velocity. 3) The flux was decreased with increasing organic loading rate due to the sludge adherance and clogging of substrate to membrane core. 4) Microorganism groups in the aeration basin was affected due to high velocity of fluidization. Protozoa numbers were rapidly decreased with increasing surface velocity.

박철휘 , 홍승모 , 허관용 , 박영재 Chul Hwi Park , Seung Mo Hong , Kwan Yong Huh , Young Jae Park

DOI: Vol.10(No.2) 96-104, 1994

The purpose of this study is to develop the advanced and high efficient upflow anaerobic reactor and put in practical use. To achieve this purpose, we built 4 reactors. 25㎥ scale each, and brought the seeding sludge for filling the reactors from K sewage treatment plant. The reactors were designed based on labotary scale reactors performed before and operated with changing the settling compartment and GSS device. During the operation, we came to get the result of DW-process characteristics. The seperation rate of gas and solid was elevated by increasing contact area and R2, R3 and R4 reactor showed good protection efficiency of 30.2, 52.5 and 23.0% from wash-out of sludge. All of 4 reactors gave over 90% COD_(nm) efficiency, 8hr HRT 6-10㎏ COD/㎥/day OLR and over 80% methane content in gas produced in the reactors.

이철우 , 민명자 , 최용진 , 임연택 , 류재근 , 서윤수 Chul Woo Lee , Myung Ja Mheen , Yong Jin Choi , Yeon Taek Rim , Jae Keun Ryu , Yoon Soo Suh

DOI: Vol.10(No.2) 105-111, 1994

Two bacterial strains essential for polyvinyl alcohol(PVA) degradation were isolated from an efficient PVA utilizing mixed culture which had been selected by screening experiments with approximately 240 samples from soils and other environmental sources. The two strains were almost unable to grow on the PVA minimal medium in each respective pure culture but the mixed culture of the two strains was found to grow symbiotically and to utilize PVA efficiently as a carbon and energy source. The two symbionts, designated KMG1 and KMG5, were identified as Pasteurella haemolytica and Psudomonas sp., respectively. The Psudomonas sp. KMG5 was confirmed to be an actual PVA degrader and the other symbiont KMGI was presumed to supply the degrader with some kind(s) of growth stimulant. In the mixed culture, the bacterial symbionts utilized almost completely 0.5% PVA at 37℃ in 7 days.

이철우 , 김철기 , 최용진 , 임연택 , 류재근 , 서윤수 Chul Woo Lee , Chul Ki Kim , Yong Jin Choi , Yeon Taek Rim , Jae Keun Ryu , Yoon Soo Suh

DOI: Vol.10(No.2) 112-119, 1994

The optimal conditions for polyvinyl alcohol(PVA) utilization by the two symbiotic isolates, Pasteurella haemolytica KMG 1 and Pseudomonas sp. KMG5 were investigated. Maximum PVA utilization occurred at pH 8.0 and 37℃ after culturing for 6 days in the minimal medium containing 0.75% PVA as a sole carbon and energy source. In the mixed culture, the KMG5 strain that had previously been proved to be the actual PVA degrader constituted the predominant population. The symbiont strains utilized equally well all types of PVA substrates irrespective of their polymerization degrees(500-30,000). The presence of additional carbon sources such as glucose, galactose, glycerol and ethanol did not affect the PVA utilizing activity of the mixed culture. On the other hand, maltose and sucrose severely inhibited the cell growth, leading to the great reduction of the level of PVA degradation. All nitrogen sources examined except urea, corn steep liquor and skim milk increased similarly and markedly the PVA degrading activity of the symbiotic culture. The growth of KMGS, one of the two symbionts was observed to be inhibited at the high temperatures above 37℃. Hence, in this study we also isolated a thermophilic mutant (KMG6) from the KMG5 cells, which enabled the mixed culture of KMG1 and KMG6 to degrade PVA effectively at 40℃.

문병현 , 윤태경 , 노병일 Byung Hyun Moon , Tae Kyung Yoon , Byung Il Noh

DOI: Vol.10(No.2) 120-127, 1994

전만식 , 김범철 Man Sig Jun , Bom Chul Kim

DOI: Vol.10(No.2) 128-135, 1994

The growth rate and the nutrients removal efficiency of water hyacinth in artificial medium were studied. Water hyacinth showed maximum growth rate at the density of 5-18㎏ wet wt./㎡, when the yield was 0.67-1.23㎏ wet wt./㎡/day. The removal rate of phosphorus and nitrogen was 153 and 1,184㎎/㎡/day, respectively. Growth rate significantly decreased at low nutrients concentration below 0.8㎎P/ℓ and 3.1㎎N/ℓ. The maximum specific growth rate(μ_(max)) of water hyacinth was 0.101day and half saturation concentration(Ks) was 0.032㎎P/ℓ and 0.410㎎N/ℓ for phosphorus and nitrogen, respectively. The shoot/root weight ratio, varying from 1.8 to 14.1, was smaller at low nutrient concentration due to the enhanced development of root. The contents of phosphorus and nitrogen in the dried tissue were 0.22-1.02% and 1.4-4.3%, respectively. The water content was 88.9-93.9%. The removal efficiencies of P and N were 90% and 71% when retention time was 5.7day, and the standing crop was 3.8㎏/㎡.