• Environmental Engineering Research
• /
• 제15권2호
• /
• pp.79-84
• /
• 2010

Three biological aerated filters (BAFs) composed of a PVC pipe with a diameter of 75 mm were constructed and operated at a waste-water temperature at $13^{\circ}C$. The media used for each BAF were: 5-mm gravel; 5-mm lava rock; 12.5-mm diameter by 15-mm long plastic rings, all with a media depth of 1.7 m. The feedwater, which simulated the effluent of aerated lagoons, had influent soluble chemical oxygen demand (sCOD) and ammonia concentrations of approximately 50 and 25 mg/L, respectively. For a hydraulic retention time (HRT) of two hours without recirculation, ammonia percent removals were 98.5, 98.9, and 97.8%, for the gravel, lava rock, and plastic rings, respectively. By increasing the effluent recirculation from 100 to 200% for an HRT of one hour, respective ammonia removals improved from 90.1 to 96, 76.5 to 90, and 65.3 to 79.5% for gravel, lava rock, and plastic rings. Based on the ammonia and sCOD loadings for different HRTs, the estimated maximum ammonia loading was approximately 0.6 kg $NH_3-N/m^3$-day for the three BAFs of different media types. The zero-order biotransformation rates for the BAF with gravel were found to be higher than the lava rock and plastic ring media. The results ultimately showed that BAF can be used as an add-on system to aerated lagoons or as a secondary treatment unit to meet ammonia discharge limits.

• 한국물환경학회지
• /
• 제33권6호
• /
• pp.754-768
• /
• 2017

Polybrominated diphenyl ethers (PBDEs) are a group of industrial aromatic organobromine chemicals that have been used since the 1970s as flame retardants in a wide range of consumer products and articles, including plastics, computers, textiles and upholstery. Commercial PBDEs were added to Annex A of the Stockholm Convention as persistent organic pollutants in May 2009. PBDEs are still frequently found in sludge and effluent from wastewater treatment plants, even though commercial PBDEs were prohibited or voluntarily phased out several years ago. Conventional wastewater treatment processes are not designed to effectively remove PBDEs. This indicates that there is an urgent need for new developments and improvements to enhance upon the treatment techniques which are currently available. Several studies have suggested the potential removal and degradation technologies for PBDEs in wastewater. In this study, the concentrations and compositional profiles of PBDE congeners in sludge and effluent are investigated by analyzing the relevant literature data in relation to their usage patterns in commercial products in North America and South Korea. The strengths and weaknesses of the current PBDEs removal techniques (i.e., biodegradation, zero-valent iron, photolysis, sorption, etc.) are discussed critically. In addition, future research direction regarding the treatment and removal of PBDEs from wastewater is also suggested, based on the literature review.

• Macromolecular Research
• /
• 제16권6호
• /
• pp.492-502
• /
• 2008

This study examined the adsorption of a synthetic cutting fluid and cutting fluid effluent on chitosan and SDS-modified chitosan, Chitosan and SDS-modified chitosan were prepared in form of beads and fibers. A series of batch experiments were carried out as a function of the initial concentration of cutting fluid, contact time and pH of the fluid. The contact angle study suggested that the SDS-modified chitosan was more hydrophobic than chitosan. The Zeta potential study showed that chitosan, SDS-modified chitosan and synthetic cutting fluid had a point of zero charge (PZC) at pH 7.8, 9 and 3.2, respectively. SDS-modified chitosan has a greater adsorption capacity than chitosan. The experimental results show that adsorption capacity of the cutting fluid on 1.0 g of SDS-modified chitosan at pH 3 and for a contact time of 120 min was approximately 2,500 g/kg. The adsorption capacity of chitosan and SDS-modified chitosan increased with decreasing pH. The Langmuir, Freundlich, and Brunauer Emmett and Teller (BET) adsorption models were used to explain the adsorption isotherm. The Langmuir isotherm fitted well with the experimental data of chitosan while the BET isotherm fitted well with the SDS-modified chitosan data. Pseudo first- and second-order kinetic models and intraparticle diffusion model were used to examine the kinetic data. The experimental data was fitted well to a pseudo second-order kinetic model. The significant uptake of cutting fluid on chitosan and SDS-modified chitosan were demonstrated by FT-IR spectroscopy, SEM and heat of combustion.

• 대한토목학회논문집
• /
• 제32권1B호
• /
• pp.79-84
• /
• 2012

질산성질소는 일반적인 지하수 오염물질로서, 본 연구에서는 영가철을 충진한 복극전해조를 이용하여 서로 다른 조건에서 질산성질소 제거실험을 수행하였다. 실험에 사용된 전해조에는 양쪽 끝에 위치한 주 전극 사이에 전도체로서 영가철이, 비전도체로서 규사가 혼합하여 충진되었다. 모의폐수(오염된 지하수를 모사하였으며 초기 질산성질소 농도 약 30 mg/L, 전기전도도 약 300 ${\mu}S/cm$)를 이용한 연속식 실험에서 인가전압 600 V, 유입유량 20 mL/min으로 최대 99% 이상의 질산성질소를 제거하였다. 최적 혼합비 및 최적 유입유량은 각각 1:1~2:1(규사:영가철), 30 mL/min으로 결정하였다. 질산성질소의 주입농도에 따라 유출수의 pH가 비례적으로 거동하였으며, 질산성질소 환원의 최종산물로서 약 60% 정도가 암모니아로 유출되었다. 실험이 끝난 후 영가철 표면에서의 산화철은 대부분 magnetite형태로 존재하였다.

• 한국물환경학회지
• /
• 제20권2호
• /
• pp.170-175
• /
• 2004

The purpose of this study was to monitor bacteria present in raw water and to investigate the effect of ozone, UV and combined ozone/UV processes for inactivating bacteria. Both polymerase chain reaction (PCR)-fragment length polymorphic analysis (PRA) and PCR-sequence analysis (PSA) were applied for the simultaneous analysis of numerous bacteria species present in each tested water, such as drinking water (DRW), drinking water source (DRWS) and sewage effluent water (SEW). According to the result, the number of detected bacteria species was zero in DRW, 58 in DRWS and 13 in SEW. After treatment of the each process, the ozone/UV process was the most successful for inactivating almost all bacteria. However, it was found that Flavobacterium sp., Pseudomonas sp. and Beta proteobacterium sp. had strong resistant to all tested processes, requiring further detailed study.

• 펄프종이기술
• /
• 제37권3호
• /
• pp.50-58
• /
• 2005

It is generally known that paper industry is the second largest industry in the use of process water, and also have the highest environmental impact load in the contaminant sources. Paper is produced from the mixtures composed of 1% fibrous raw materials and 99% water. The optimum use of process water effects on the quality properties of paper and the environmental impact load of waste water treatment. In this research, the kinds of fibrous raw material & additives used in the paperboard production line were investigated, and the quantification of environmental loads and the environmental effects of process water on COD potential were evaluated. The NBDCODs were also analyzed from process water by the method of waste water treatment in paper mill and applied for the optimum use of recycling water, and zero effluent process. In the fibrous raw materials, KOCC caused the highest COD potentials, and sack paper & UKP was comparatively low. The NBDCOD of KOCC largely reduced after biological treatment because of easily biodegradable properties, but AOCC contained non-biodegradable materials. In chemical additives, COD was high in turns of rosin>starch>deaeration agent>dye, NBDCOD greatly reduced in starch and deaeration agent. In the case of 2 kinds of paperboard product, the COD potentials was mainly high in starch, AOCC and KOCC.

• Journal of Microbiology and Biotechnology
• /
• 제16권11호
• /
• pp.1720-1727
• /
• 2006

To set up a kinetic model that can provide a theoretical basis for developing a new mathematical model of the Cr(VI) biosorption column using brown seaweed Ecklonia biomass, a differential reactor system was used in this study. Based on the fact that the removal process followed a redox reaction between Cr(VI) and the biomass, with no dispersion effect in the differential reactor, a new mathematical model was proposed to describe the removal of Cr(VI) from a liquid stream passing through the differential reactor. The reduction model of Cr(VI) by the differential reactor was zero order with respect to influent Cr(IlI) concentration, and first order with respect to both the biomass and influent Cr(VI) concentrations. The developed model described well the dynamics of Cr(VI) in the effluent. In conclusion, the developed model may be used for the design and performance prediction of the biosorption column process for Cr(VI) detoxification.

• 한국펄프종이공학회:학술대회논문집
• /
• 한국펄프종이공학회 2006년도 PAN PACIFIC CONFERENCE vol.2
• /
• pp.441-444
• /
• 2006

A lot of water is using in the paper mill for dilution, washing, sealing, and other process operation. As the regulation of water environment has been more tightened than ever before, water management in the paper mill becomes the most important task. Topics on reducing fresh water and increasing recycling water have been studied. Further, an interest in zero-effluent system has been increased. The pH of waste water in paper mill is usually weak acidic or neutral. The waste water in the paper mill includes water insoluble organic materials that are not easy to be dissolved in the water, inorganic materials that never react with water and chemical additives that are used to recycled fiber. This study investigated on the effect of various materials used in paper mill on COD. This data could be used to control the environmental load in paper mill. COD caused by raw materials and NBDCOD (Non Bio Degradable COD) after the activated sludge process are investigated in this study. Results obtained in this study can be used in a simulation program designed to control environmental load in the paper mill.

• 한국지반공학회논문집
• /
• 제18권5호
• /
• pp.143-157
• /
• 2002

주물사의 일반적인 지하수 오염물질인 TCE에 대한 반응성을 조사하기 위해 batch와 column실험을 하였다. 본 실험에서 얻어진 주물사의 반응성은 실제 반응벽체에 쓰여지는 철에 비해 높거나 비슷한 결과를 나타내었다. 또한, 주물사에 포함된 클레이와 TOC에 의해 TCE의 이동이 급격히 감소하는 것을 관찰하였다. 따라서, 실제 현장 상황에서는 토양미생물에 의한 분해에 의해 계산된 값보다 훨씬 낮은 농도의 TCE가 검출되리라 예상된다. 실제 현장 반응벽체 설계에 있어서 1 m두께의 벽체가 설치되기 위해서는 주물사에 포함된 철의 함량이 1%이상이면 안전측으로 벽체설계가 가능하다고 볼 수 있다.

• Membrane and Water Treatment
• /
• 제13권3호
• /
• pp.139-145
• /
• 2022

Development in advanced separation processes leads to the significant advancement in polymeric membrane preparation methodology. Therefore, present research investigated the preparation and characterization of cellulose acetate membrane by phase inversion separation method to determine optimized operating parameters. Prepared CA membrane's performance was been analyzed in terms of % rejection and flux. Investigation was conducted to study effect of different parameters such as polymer concentration, evaporation rate, thickness of film, coagulation bath properties, temperature of polymer solution and of the coagulation bath etc. CA membrane was fabricated by taking polymer concentration 10wt% and 11wt% with zero second evaporation time and varying film thickness over non-woven polyester fabric. Effect of coagulation bath temperature (CBT) and casting solution temperature were also been studied. The experimental results from SEM showed that the surface morphology had been changed with polymer r concentration, coagulation bath and casting solution temperature, etc. Lower polymer concentration leads to lower precipitation time giving porous membrane. The prepared membrane was tested for advanced waste water treatment of relevant effluent stream in pilot plant to study flux and rejection behavior of the membrane.