• Journal of the Korean Chemical Society
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• v.54 no.1
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• pp.115-119
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• 2010

Neutral red5 (BR 5) adsorption from aqueous solution was investigated. New solid adsorbent was prepared from paper sludge incinerated at $250^{\circ}C$ during 2 hours. Experiments were carried out, in batch system, to remove RB5 dye from the synthetic waste water. Maximum adsorption of 374.98 mg/g at pH 5, at room temperature and contact time of 80 min was obtained. The Langmuir and Freundlich adsorption models were applied to interpret the equilibrium isotherm. The Freundlich isotherm fits quite well with the experimental data (with highly regression coefficient $R^2$). The incinerated sludge solid samples untreated and treated with BR5 dye were characterized by FT-IR spectrophotometer.

• Water for future
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• v.22 no.1
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• pp.117-125
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• 1989

This study deals with the performance of an acivated sludge system which is modified by the researcher to function without any additional chemical or internal recyle in removing organics, nitrogen, and phosphorus from synthetic wastewater. To improve the nutrient removal efficiency, the researcher utilized the anoxic, anaerobic, and aerobic reactor sequences with a single sludge return, whiched to nitrification/denitrification and phosphorus release/overplus accumulation. A bench scale system was operated with a view to investigating the reaction characteristics of each reactor, and to measuring the biological kinetic coefficients(Y, $K_d$, k, $K_s$) for theremoval of COD in relation to the mean cell residence time at five different MLSS concentrations, 5000, 4200, 3300, 2600, and 1900 mg/l. The results of the research showed that organic substance and nutrient were removed simultaneously by this modified activated sludge process. And the process kad 66%-99% ortho-p removal efficiency.

• Journal of Environmental Science International
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• v.11 no.4
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• pp.367-373
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• 2002

The polycyclic aromatic hydrocarbons(PAHs) content in sewage sludge was determined by gas chromatography linked to ion trap mass spectrometry(GC/ITMS) with five deuterated PAHs as internal standards. The minimum detection limit was from 1.66 to 7.14 pg for individual PAH by GC/ITMS. For determining total PAHs(∑PAH) in sewage sludge 84 samples from 74 waste water treatment plants in whole country were analyzed. The average content of ∑PAH far whole samples was 3,289$\pm$3,098 $\mu\textrm{g}$/kg, and ranged from 142 to maximum 20,102 $\mu\textrm{g}$/kg. According to the number of population of the city, the areas were classified as five regions, ie. big, large, middle, small, and rural area in which the waste water treated plants were grown. The contents of PAHs were 4,689$\pm$5,503, 5,839$\pm$6,401, 3,725$\pm$2,053, 2,237$\pm$2,069, and 2,475$\pm$1,489 $\mu\textrm{g}$/kg, in big, large, middle, small, and rural area, respectively.

• Membrane and Water Treatment
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• v.13 no.4
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• pp.183-189
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• 2022

This study seeks towards an optimal way to control sulfate ions in semiconductor wastewater effluent with potential eco-toxicity. We developed a system based on ettringite (Ca₆Al₂(SO₄)₃(OH)₁₂·26H₂O). The basic idea is that the pH of the water is raised to approximately 12 with Ca(OH)₂. After, aluminium salt is added, leading to the precipitation of ettringite. Lab-scale batch and continuous experiment results with real semiconductor wastewater demonstrated that 1.5 and 1 of stoichiometric quantities for Ca²⁺ and A³⁺ with pH above 12.7 could be considered as the optimal operation condition with 15% of sludge recycle to the influent. A mixed AlCl₃ + Fe reagent was selected as the beneficial Al³⁺ source in ettringite process, which resulted in 80% of sludge volume reduction and improved sludge dewaterability. The results of continuous experiment showed that with precipitation as ettringite, sulfate concentration can be stably reduced to less than 50 mg/L in effluent from the influent 2,050 ± 175 mg/L on average (1,705 ~ 2,633 mg/L).

• 제어로봇시스템학회:학술대회논문집
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• 1990.10a
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• pp.209-212
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• 1990

The activated sludge process is a commonly used method for treating sewage and waste waters. The process is characterized by a lack of measurement instrumentations and control goals that are neither well defined nor well understood. In the present study the concept of fuzzy control is employed for such process in which a design method for fuzzy controller based on a multivariable fuzzy reasoning algorithms is investigated and then simulation results are presented.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.6
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• pp.1001-1009
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• 2000

This study is to find the utilization of intermittent aeration system, around S-COD, T-COD, SS, timewise changes of treatment performance, sludge conversion yield, changes of temperature and pH, etc. In consequence of this study, factors of temperature correction showed 1.052 on continuous aeration, and 1.056 on intermittent aeration which is more sensitive to temperature through a minute degree. Meanwhile, sludge conversion yield on intermittent aeration showed lower and more economical than that on continuous aeration. In case of changing pH, treatment water of both reactors worsened slightly in acid but improved in alkali. In general. considering the quality of effluent water, variation pH of effluent water, etc. the case of intermittent aeration was more favorable than that of continuous aeration.

• Journal of the Korean Wood Science and Technology
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• v.48 no.3
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• pp.271-282
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• 2020

Sewage treatment plants are social infrastructure of cities. The sewage distribution rate in Korea is reaching 94% based on the sewage statistics based in the year of 2017. In Korean sewage treatment plants, use of PAC (Poly Aluminum Chloride) accounts for 58%. It contains a large amount of impurities (heavy metal) according to the quality standards, however, there have been insufficient efforts to reinforce the standards or technically improve the quality, which resulted in secondary pollution problems from injecting excessive coagulant. Also, the increase in the use of chemicals is leading to the increases in the annual amount of sewage sludge generated in 2017 and the need to reuse sludge. As such, this study aims to verify the possibility of reusing sludge by evaluating the stability of heavy metals based on the injection of coagulant mixture during water treatment which uses the torrefield wood powder and natural materials, and evaluating the sedimentation and heating value of sewage sludge. As a result of analyzing heavy metals (Cr, Fe, Zn, Cu, Cd, As, Pb, and Ni) from the coagulant mixture and PAC (10%), Cr, Cd, Pb, Ni, and Hg were not detected. As for Zn, while its concentration notified in the quality standards for drinking water is 3 mg/L, only a small amount of 0.007 mg/L was detected in the coagulant mixture. Maximum amounts of over double amounts of Fe, Cu, and As were found with PAC (10%) compared to the coagulant mixture. Also, an analysis of sludge sedimentation found that the coagulant mixture showed a better performance of up to double the speed of the conventional coagulant, PAC (10%). The dry-basis lower heating value of sewage sludge produced by injecting the coagulant mixture was 3,378 kcal/kg, while that of sewage sludge generated due to PAC (10%) was 3,171 kcal/kg; although both coagulants met the requirements to be used as auxiliary fuel at thermal power plants, the coagulant mixture developed in this study could secure heating values 200 kal/kg higher than the counterpart. Therefore, utilization of the coagulant mixture for water treatment rather than PAC (10%) is expected to be more environmentally stable and effective, as it helps generating sludge with better stability against heavy metals, having a faster sludge sedimentation, and higher heating value.

• Journal of Korean Society on Water Environment
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• v.22 no.1
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• pp.59-65
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• 2006

The effluent limitations for individual industry based on the best available technology economically achievable (BAT) have been required to achieve effective regulation. BAT assessment criteria that are suitable for the circumstances of Korean industry were developed in the previous study. The criteria were applied to determine the BAT for petrochemical basic compound manufacturing (PBCM) and plastics and synthetic resins manufacturing (PSRM) industry. Wastewater discharged from the each category contains high concentration of COD and toluene. Eighteen sites were surveyed and wastewater qualities were analyzed. Six and two different technologies were applied to the PBCM and PSRM industry for the end-of-pipe treatment process, respectively. The technology candidates were evaluated in terms of environmental impacts, economically achievability, treatment performance and economical reasonability. As the result, the technology options: typical activated-sludge process + sand filtration + activated carbon adsorption (PBCM) and wet oxidation + chemical precipitation + typical activated-sludge process + chemical precipitation (PSRM) were selected as the BAT for each industry.

• Journal of Environmental Health Sciences
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• v.32 no.1 s.88
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• pp.96-101
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• 2006

Chlorination inhibition on the organic removal activity of activated sludge microorganism was investigated in this study. It is well known that chlorination improves the settleability of filamentous bulking sludge through the selective impediment of filamentous microorganisms. However, it is based on the declination of effluent water quality after actual chlorination in dairy wastewater treatment plant. In case of the activated sludge which was exposed in the suggested concentration of chlorine $7.5\;mgCl_2/gVSS/day$ for the filamentous bulking control, decrease of organic uptake rate of $4.9\~24.0\%$, and dentrification rate of $24.8\~30.3\%$ ware shown in comparison to the control group which was not reacted with chlorine. As a result of comparing floc size of activated sludge microorganism, the average of floc diameter in the chlorine exposed group was $150\;{\mu}m$, which displays $25\%$ decrease compared with the control group.

• Membrane and Water Treatment
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• v.4 no.3
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• pp.175-189
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• 2013

A membrane bioreactor (MBR) with sludge retention time (SRT) of 300 days was maintained for over 2 years. Polypropylene microfiltration (MF) membrane with pore size of 0.2 ${\mu}m$ was used in the MBR system. The fouling behaviors of various sludge fractions from the MBR were studied and sub-divided resistances were analyzed. It was observed that $R_{cp}$ was a dominant resistance during the filtration of activated sludge, contributing 63.0% and 59.6% to the total resistance for MBR and sequential batch reactor (SBR) respectively. On the other hand, $R_c$ played the significant role during the filtration of supernatant and solutes, varying between 54.54% and 67.18%. Compared with $R_{cp}$ and $R_c$, $R_{if}$ was negligible, and $R_m$ values remained constant at $0.20{\times}10^{12}m^{-1}$. Furthermore, resistances of all sludge fractions increased linearly with rising mixed liquor suspended solids (MLSS) concentration and growing trans-membrane pressure (TMP), while the relationship was inversed between fraction resistances and cross flow velocity (CFV). Among all fractions of activated sludge, suspended solid was the main contributor to the total resistance. A compact cake layer was clearly observed according to the field emission scanning electro microscopy (FE-SEM) images.