• Journal of Forest and Environmental Science
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• 제23권2호
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• pp.73-78
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• 2007

Ultrasonic deinkings of white ledger were carried out to confirm whether the ink removal efficiency and pulp qualities can be improved by the ultrasonic deinking. The effects of conventional pulping and ultrasonic treatment of white ledger on the ink particle size distribution and ink removal coefficient were compared. The physical properties of paper, energy consumption and effluent qualities were measured. The ultrasonic treatment of white ledger resulted in the ink particle size distribution suitable for flotation. The ink removal efficiency, brightness, breaking length and effluent quality were improved by the ultrasonic deinking. It is expected that the competitiveness of ultrasonic deinking system can be improved by the optimization of treatment condition.

• 대한환경공학회지
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• 제33권1호
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• pp.25-31
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• 2011

본 연구에서는 하수처리공정의 유출 수질을 안정적인 유지하기 위하여, 유입수 패턴을 이용한 모델 기반 $NH_4-N$ 예측 제어 알고리즘을 개발하고 $A^2/O$ 공정을 대상으로 적용 및 평가하였다. 평가에 사용된 자료는 B 시 S 하수처리장에 위치한 pilot 규모의 $A^2/O$ 공정 운전자료를 사용하였다. 생물학적 반응조를 모사하기 위해 수정된 ASM3+bio-P 모델(Lee, 2003)을 사용하였고, 침전조 농도 거동 모사를 위해 일차원 이중 지수 함수 모델(Takacs et al., 1991)을 사용하였다. 유입수 패턴을 이용하여 하루 뒤 유출수 $NH_4-N$ 농도를 예측하고, 사전 작성된 $NH_4-N$ 제어 schedule을 사용하여 pilot plant의 호기조 DO를 조절하는 제어 로직을 적용하였다. 제어 적용성을 평가하기 위해 제어를 적용하지 않은 경우와 적용한 경우를 비교하였고, 계절적 영향을 알아보기 위해 여름철과 겨울철에 $NH_4-N$ 제어 schedule을 적용한 실험을 하였다. 여름철 및 겨울철 모두 제어를 적용하지 않은 경우 수질기준을 초과하는 사례가 발생하였지만, 제어를 적용한 경우 목표수질 이내의 안정적인 유출수질이 방출됨을 확인하였다. 제어를 적용하지 않은 경우에 비교해서, 예측 제어를 적용한 경우에는 송풍기의 RPM이 약 9.1% 증가하였고, 유출수의 $NH_4-N$ 농도는 약 45.2% 감소하였다. 이를 통해 본 연구에서 개발된 유출수 $NH_4-N$ 예측 제어 알고리즘 적용으로 인한 운영비용 증가 대비 수질 개선 효과가 크게 나타났기 때문에, 안정적인 유출수 확보를 위한 측면에서 효율적인 제어기법으로 판단된다.

• 한국물환경학회지
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• 제22권5호
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• pp.905-912
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• 2006

In this paper, simulation methods of the system dynamics model developed by Das et al. (1997) for activated-sludge wastewater treatment plants are illustrated in an attempt to determine the operating rules and the policies related to capacity expansion of an activated-sludge wastewater treatment plant. For existing conditions, the analyses were performed by varying activated-sludge return rate to observe changes in effluent water quality and treatment efficiency. The effluent water quality is also analyzed for various average daily inflow conditions and activated-sludge return rates. As a result, without expanding the aeration tank, maximum average daily inflow that can satisfy the effluent water quality standard of BOD $0.02kg/m^3$ was determined as $2,840m^3/hr$, subject to 100% of activated-sludge return rate while other factors remain constant. When the activated-sludge return rate is less than 100%, expansion of the aeration tank is necessary and minimum sizes of the aeration tank to satisfy the effluent water quality standard were determined for various activated-sludge return rates. In addition, the total operating and maintenance as well as unit treatment cost regression equations for activated-sludge wastewater treatment plants are suggested by using the cost data that are obtained from Water and Wastewater Division, Ministry of Environment. The regression analyses showed that the economies of scale phenomena exist in the operating and maintenance costs of activated-sludge wastewater treatment plants.

• 한국환경보건학회지
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• 제30권3호
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• pp.185-190
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• 2004

Acute aquatic toxicity of effluents discharged from five dyeing plants in Gyeong-gi province were evaluated to assess whether the current Korean water quality standards(KWQS) could protect aquatic life. Chemical analyses of all parameters regulated under KWQS, except for E-coli, were also carried out to determine regulation compliance of the samples. All the effluent samples were satisfied with KWQS except for the color in only one sample. In acute Daphnia magna toxicity tests, significant mortality was observed in one of five samples and EC50 was 12.1%(95% confidence interval 9.1-16.2), which was in compliance with KWQS. The result of the Microtox assay indicated that acute microbial toxicity existed in effluents from three out of five plants, two of which were in compliance with KWQS. The agreement between regulation compliance of chemical concentrations of effluent and observed toxicity from various biological toxicity tests was very poor to fair (kappa = 0.194~0.250). The data presented suggest that exposure to dyeing wastewater which were in compliance with Korean water quality standards may not be safe to aquatic biota, and multiple tropical levels should be considered in aquatic toxicity monitoring of dyeing industry.

• 한국환경과학회지
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• 제15권3호
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• pp.237-242
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• 2006

The purpose of this research was to investigate the efficiency of coagulants dose after backwashing. The turbidity of initial effluent was high after backwashing in the rapid sand filtration and the high turbidity was almost removed by coagulants dose into filter-sand after backwashing. It was found that the turbidity of initial effluent was well removed by all kinds of the coagulants used in this study. When filtration was performed input water with differentiated pH's, the turbidity of effluent was low at the range of pH 5 - pH 7. But the removal was not good about over pH 9. This result was considered into the existence forms of aluminium, $Al(OH)^{2+}\;and\;{Al(OH)_2}^+$ at pH 5. Cryptosporidiums of effluent were 4/ml for ten minutes immediately after back washing and 3/ml until sixty minutes. However, the case of coagulant dose after backwashing, Cryptosporidiums of effluent were 0.5/ml for ten minutes with no detection after twenty minutes.

• 환경위생공학
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• 제22권2호
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• pp.41-52
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• 2007

K leather industry wastewater treatment plant(advanced treatment process) was selected to evaluate effluent quality and pollutants removal efficiencies. $BOD_5$ concentration of effluent was $3.95mg/{\ell}$ and its removal efficiency was 99.8%. Also, most of other pollutants removal efficiencies were over 90% as well. And 95% reliability of effluent concentration were $106.8mg/{\ell}$ of CODmn, $86mg/{\ell}$ of SS, $72.04mg/{\ell}$ of TN that is greater than the effluent limitation, $0.98mg/{\ell}$ of ABS, $1.8mg/{\ell}$ of n-Hexane, $9.7mg/{\ell}$ of $BOD_5$ and $0.11mg/{\ell}$ of Cr.

• Asian-Australasian Journal of Animal Sciences
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• 제17권1호
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• pp.137-145
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• 2004

Intensive animal industries create large volumes of nutrient rich effluent which, if untreated, has the potential for substantial environmental degradationand to recover valuable nutrients that would otherwise be lost. Members of the family Lemnaceae are widely used in lagoon systems, to achieve inexpensive and efficient remediation of effluent. Only limited research has been conducted into their growth in highly eutrophic media and there has been little done to systematically distinguish between different types of media. This study examined the growth characteristics of duckweed in abattoir effluent and explored possible ways of ameliorating the inhibitory factors to growth on this medium. A series of pot trials was conducted to test the tolerance of duckweed to abattoir effluent partially remediated by a sojourn in anaerobic fermentation ponds, both in its unmodified form and after the addition of acid to manipulate pH, and the addition of bentonite. Unmodified abattoir effluent was highly toxic to duckweed, even at dilutions of 3:1. Duckweed remained viable and grew sub-optimally in simplified media with total ammonia nitrogen (TAN) concentrations of up to 100 mg/L. Duckweed grew vigorously in effluent diluted 1:4 v/v, containing 56 mg TAN/L when modified by addition of acid (to decrease pH to 7) and bentonite at 0.5%. The results of this study suggest that bentonite plays an important role in modifying the toxicity of abattoir effluent to duckweed.

• 대한환경공학회지
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• 제27권2호
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• pp.177-183
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• 2005

하 폐수 처리장의 방류수 수질은 최종 침전지의 성능에 의해 직접적으로 영향을 받으므로 최종 침전지의 효율적 설계 및 운전은 하 폐수 처리에 소요되는 비용 절감과 더불어 수질보전을 위한 하수 정화의 목표를 달성할 수 있다. 그러므로 본 연구에서는 장방형 최종 침전지의 성능 개선을 위하여 유입구 위치와 정류벽 설치에 따른 내부 유동특성 및 고형물질의 제거효율을 수치해석방법을 통해 평가하였다. 개발된 2차원 컴퓨터 프로그램은 방사성 추적자를 이용한 체재시간분포 곡선과의 비교를 통해 성공적으로 검증된 수치해석 모델로 수력학적 구조변경에 대한 침전지의 성능 예측을 가능하게 하였다. 최종 침전지의 유입구 위치는 낮을수록 침전지에 형성된 강력한 바닥흐름과 수표면 역흐름으로 나타나는 밀도류를 저감시켰으며 침강된 슬러지의 하류 이동을 감소시켰다. 최종 침전지 유입부에 설치된 정류벽은 유입수가 출구로 직접 흐르는 단락류를 방지하고 밀도 저류로 유입되도록 하여 방류수 수질을 향상시키나 유입구 위치가 낮은 경우에 설치된 정류벽은 오히려 방류수 수질을 떨어뜨리는 결과를 초래하였다. 결국 최종 침전지의 성능 개선을 위한 수력학적 구조변경 및 설계는 다양한 변수에 대한 조직적인 수치해석 연구가 필요하며 선행되어야 할 것으로 판단된다.

• 한국미생물·생명공학회지
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• 제28권6호
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• pp.361-366
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• 2000

Genera and number of protozoa were investigated in the conventional activated sludge pilot plant used for the treatment of municipal sewage and pre-treated night soil-containing sewage. In both case, the predominant protozoa was ciliates and among them Vorticella was the most common. In the pilot plant where pre-treated night soil was mixed with municipal sewage, genera of free-swimming ciliates, flagellates and amoeba was higher than in those withour night soil. Correlation analysis on the quality of effluent and protozoa indicates that municipal sewage has positive correlation with protozoa. However in the pilot plan 샐 sewage contatinin pre-treated night coil soil more samples show negative correlation. Followed equations were derived by the regression analysis of BOD in both the pilot plants. In case of pilot plant A of municipal sewage, the analysis B of munici-pal and pre-treated night soil-containing sewage, the analysis of BOD was $6.731$\times$10_{-2}$ $\times$Bodo+0.306(Adjusted $R^2$=0.864). At low temperature, number of protozoa was decreased to 35% and among therm, Aspidisca was the most common genus. Therefore, protozoa can be used as indicator of quality of the effluent in sewage treatment plants.

• 한국해양공학회지
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• 제22권2호
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• pp.34-41
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• 2008

As a basic study for developing a forecasting/estimating system that predicts water quality changes when Deep Sea Water (DSW) drains to the ocean after using it, this study was carried out as follows: 1) numerical simulation of the present state at DSW developing region in the East sea using SWEM, 2) numerical prediction of water quality changes by effluent DSW, 3) analysis of influence degree 'With defined DEI (DSW effect index) at F station. On the whole, when DSW drained to the ocean, Chl-a, COD and water-temperature were decreased and DIN, DIP and DO were increased by effluent DSW, and Salinity was steady. According to analysis of influence degree, the influence degree of DIN was the highest and it was high in order of Chl-a, COD, Water-temperature, DO, DIP and Salinity. The influence degree classified by DSW effluent position was predicted that suiface outflow was lower than bottom outflow. Ad When DSW discharge increased 10 times, the influence degree increased about $5{\sim}14$ times.