• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2003년도 추계학술발표회
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• pp.73-77
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• 2003

Red mud is a waste material formed during the production of alumina when the bauxite ore is subjected to caustic leaching. It is a brick-red colored highly alkaline (pH 10-12) sludge containing mostly oxides of iron, aluminum, titanium, and silica. Red mud, due to its high aluminum, iron, and calcium contents, has been suggested as a cheap adsorbent for removal of toxic metals (e.g., As, Cr, Pb, Cd) as well as for water or wastewater treatment. The basic advantage of red mud is its versatility in application. This study was conducted to evaluate the effect of red mud on stabilization and fixation of heavy metals (such as Pb, Cu, C $r^{6+}$, Cd, Zn) contained in the Al-coating sludge and soil. The results showed that the concentration of heavy metals leached from the treated sludge and soil was low, meeting the regulatory permit level.

• Membrane and Water Treatment
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• 제9권4호
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• pp.245-253
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• 2018

The aim of this study is to investigate the membrane fouling in a thermophilic membrane bioreactor (TMBR) operated different sludge retention times (SRTs). For this purpose, TMBR was operated at four different SRTs (10, 30, 60 and 100 days). Specific cake resistance (${\alpha}$), cake resistance, gel resistance, total resistance, MFI (modified fouling index) and FDR (flux decrease ratio) were calculated for all SRTs. It was observed that flux in the membrane increases with rising SRT although the sludge concentrations in the TMBR increased. The steady state flux was found to be 31.78; 34.70; 39.60 and 43.70 LMH ($Liter/m^2/h$) for the SRTs of 10, 30, 60 and 100 days respectively. The concentrations of extracellular polymeric substance (EPS) and soluble microbial product (SMP) decreased with increasing SRT. The membrane fouling rate was higher at shorter SRT and the highest fouling rate appeared at an SRT of 10 d. Both the sludge cake layer and gel layer had contribution to the fouling resistance, but the gel layer resistance value was dominant in all SRTs.

• 환경위생공학
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• 제21권3호
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• pp.37-43
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• 2006

Recently, needs for reuse of sludge produced from WTP(water treatment plant) have been increased with shortage of landfill sites and difficulties of the treatment and disposal processes. Therefore, Reusing is becoming an Increasingly popular waste management alternative to divert waste from landfills. In order to research the characteristics of WTP sludges, we used the sludges of C WTP which intake the lake Dae-Cheong and the sludges of S WTP which intake Keum river, The specific surface area of C and S WTP sludges were $0.9986m^2/cc\;and\;1.874m^2/cc$, respectively. The gravity was about $2.0{\sim}2.4$ which are scope of peat or loamy clay. The major minerals of C WTP sludges were kaolinite(48.4%), muscovite(19.5%), and quartz(16.7%). Also, muscovite(31.6%), quartz(30.3%), and kaolinite(17.3%) in S WTP sludges were major minerals.

• 한국환경과학회지
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• 제25권8호
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• pp.1155-1163
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• 2016

The treatment efficiencies of domestic sewage treatment processes were analysed and assessed to suggest and design a suitable technology for coal seam gas (CSG) water treatment. Two sewage treatment plants (S and G in Busan) were selected. The former operates with standard activated sludge and modified Ludzak Ettinger processes while the later uses the combination of $A_2/O$ and gravity fiber filtration. For both plants, the concentrations of BOD, $COD_{Mn}$, T-N and T-P were about 5.0, 19.0, 5.0, 11.0 and 1.0 ppm, respectively, which satisfy the discharge standards. Therefore, although sewage treatment processes seems to be applicable for CSG water treatment, additional processes to remove total dissolved solids and ionic compounds (i.e. bicarbonate) need to be introduced to produce fit-for-purpose water resources for beneficial use (in accordance with Water ACT 2013). This, for the CSG treatment process design, it is necessary to align the operating conditions with merging methods of combinable unit technology obtained from sewage treatment processes.

• Membrane and Water Treatment
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• 제9권4호
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• pp.255-262
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• 2018

This study attempted to evaluate the process of self-forming dynamic membrane formation on mesh filter in membrane bioreactor with a two-stage method of batch (agitation) and continues (aeration) stage at different sludge concentrations. Four concentrations of activated sludge including $6{\pm}0.4$, $8{\pm}0.5$, $10{\pm}0.3$, $14{\pm}0.3g/L$ were used to demonstrate the optimal concentration of sludge for treating municipal wastewater and reducing fouling in dynamic membrane bioreactor. The formation time and effluent turbidity were decreased in the batch stage when increasing the activated sludge concentration. The minimum values of formation time and effluent turbidity were 14 min and 43 NTU for the optimum mixed liqueur suspended solids of $8{\pm}0.5g/L$, respectively. To improve operational condition and fouling reduction in the aeration stage, critical fluxes were measured for all concentrations by flux-step method. With increasing the sludge concentration, the relevant critical fluxes reduced. The optimum subcritical flux of $30L/m^2/h$ was applied as operating flux in the second stage. The maximum COD removal efficiency of 98% was achieved by the concentration of $8{\pm}0.5g/L$. Compressibility index of self-forming dynamic membrane and transmembrane pressure trend remained somewhat constant until the optimal concentration of $8{\pm}0.5g/L$ and thereafter they increased steeply.

• Membrane and Water Treatment
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• 제15권1호
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• pp.1-9
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• 2024

Biological nutrient removal is gaining increasing attention in wastewater treatment plants; however, it is adversely affected by low temperatures. This study examined temperature effects on nutrient removal and morphological stability of the granular and denitrifying phosphorus accumulating organisms (PAO and DPAO, respectively) using sequencing batch reactors (SBRs) at 5, 10, and 20 ℃. Lab-scale SBRs were continuously operated using anaerobic-anoxic and anaerobic-oxic cycles to develop the PAO and DPAO granules for 230 d. Sludge granulation in the two SBRs was observed after approximately 200 d. The average removal efficiency of soluble chemical oxygen demand (SCOD) and PO₄^3--P remained >90% throughout, even when the temperature dropped to 5 ℃. The average removal efficiency of NO₃^--N remained >80% consistently in DPAO SBR. However, nitrification drastically decreased at 10 ℃. Hence, the removal efficiency of NH₄⁺-N was decreased from 99.1% to 54.5% in PAO SBR. Owing to the increased oxygen penetration depth at low temperatures, the influence on nitrification rates was limited. The granule in DPAO and PAO SBR was observed to be unstable and disintegrated at 10 ℃. In conclusion, morphological characteristics showed that changed conversion rates at low temperatures in aerobic granular sludge altered both nutrient removal efficiencies and granule formation.

• Asian-Australasian Journal of Animal Sciences
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• 제6권2호
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• pp.205-209
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• 1993

A new treatment system for animal waste water has been developed as an alternative to the activated sludge process. It consists of two treatments; one is operated with 7 tanks, and the other is soil and plant cultivation bed. Aerobic microorganisms are added to the influent water in the tanks where the water is aerated so that the microbes utilize the pollutants, while sedimentation removes the indigestible solids. In the secondary treatment the water, which has already received a primary treatment, is filtered through soil where it also receives treatment by soil organisms. In addition there is transpiration of water and absorption of minerals by plants. In the primary treatment BOD, SS, coliforms (E. coli), TP and total bacteria were removed 79-99%, but COD and TN were removed only 58% and 36%, respectively. In the secondary treatment removal of nutrients proceeded further, and 93-99% of pollutants were removed. The treated waters met the quality standard of discharge water in Japan except for TN, which was in too great a concentration to meet discharge standards. This problem requires further study.

• 공업화학
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• 제20권3호
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• pp.241-250
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• 2009

지난 수 년간 본 연구팀은 새로운 티탄염 응집제를 이용하여 폐수를 응집한 후 생산된 슬러지에서 산화티탄을 생산하는 연구를 진행하였다. 티탄염의 응집 효율은 일반적으로 많이 사용되는 철염과 알루미늄염 응집제와 비슷하였으며 슬러지를 소성하여 제조한 산화티탄은 상용 산화티탄보다 더 넓은 표면적과 높은 광촉매 활성을 나타내었다. 산화티탄의 광촉매 활성 향상과 pH를 높이기 위해 응집보조제로서 철, 알루미늄, 칼슘을 사용하여 광촉매 활성이 높은 Fe, Al, Ca 도핑 산화티탄을 제조하였다. 이 기술의 실제 적용 가능성을 확인하기 위하여 염색폐수 파일럿 장치에 적용한 결과, 우수한 유기물 제거 능력과 빠른 응집체 형성이 확인되었다. 염색폐수 슬러지에서 제조한 산화티탄은 높은 유기물 제거 광촉매 활성과 물 광분해에 의해 수소를 생성하였다. 티탄염 응집제와 슬러지에서 제조한 산화티탄의 독성을 D. magna로 조사한 결과, 낮은 독성을 확인할 수 있었다. 이 총설은 미래의 슬러지 재활용 기술로 높은 적용 가능성을 가지는 티탄염으로 제조한 산화티탄의 특성을 체계적으로 정리하였다.

• 대한환경공학회지
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• 제34권10호
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• pp.651-655
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• 2012

본 연구에서는 천연 무기소재로부터 합성된 무기개량제의 슬러지 탈수능 개선 효과를 상용 유기고분자응집제와 비교 평가하였다. 2.0 mg/g sludge TS의 주입량에서 무기개량제는 여과시간, 여과비저항계수, 탈수케이크 함수율, 탁도를 각각 146에서 41초로, $8.3{\times}10^{14}$에서 $2.4{\times}10^{14}$ m/kg로, 82.1에서 77.1%로, 112에서 61.1 NTU로 향상시켰으며, 이는 상용 양이온 유기고분자 응집제에 필적하는 성능이었다. 따라서 무기개량제를 하수슬러지의 대체 개량제로서 활용 가능할 것으로 판단된다. 각 탈수능 성능지표 간의 상호 관계를 분석한 결과, 여과시간, 여과비저항계수, 탈수케이크 함수율 간에 강한 상호관계가 확인되었다.

• 상하수도학회지
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• 제28권2호
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• pp.161-170
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• 2014

It is essential to decrease energy consumption and excess sludge to economically operate sewage treatment plant. This becomes more important along with a ban on sea dumping and exhaustion of resource. Therefore, many researchers have been study on energy consumption reduction and strategies for minimization of excess sludge production from the activated sludge process. The aeration cost account for a high proportion of maintenance cost because sufficient air is necessary to keep nitrifying bacteria activity of which the oxygen affinity is inferior to that of heterotrophic bacteria. Also, additional costs are incurred to stabilize excess sludge and decrease the volume of sludge. There were anoxic, aerobic, membrane, deairation and concentration zone in this MBR process. Continuous aeration was provided to prevent membrane fouling in membrane zone and intermittent aeration was provided in aerobic zone through ammonia sensor. So, there was the minimum oxygen to remove $NH_4-N$ below limited quantity that could be eliminated in membrane zone. As the result of this control, energy consumption of aeration system declined by between 10.4 % and 19.1 %. Besides, we could maintain high MLSS concentration in concentration zone and this induced the microorganisms to be in starved condition. Consequentially, the amount of excess sludge decrease by about 15 %.