• Journal of Korean Society of Environmental Engineers
• /
• v.27 no.1
• /
• pp.93-100
• /
• 2005

Comparative thickening and dewatering characteristics of municipal wastewater sludge were investigated in terms of separated and combined treatment of primary and secondary BNR sludge. Also, various conditioning methods such as cation polymer addition, steam and ultrasonication treatment were examined to improve dewaterability of sludge. The dewaterability was measured by using specific resistant test, wedge zone simulator and centrifuge. The result of the sludge thickening test revealed that separated thickening was better in terms of solids recovery and supernatant quality. Particularly, the thickening of primary sludge with high solids (about 3.5% TS) showed very poor solid separation. The addition of cation polymer showed better conditioning characteristic for dewatering and the optimal polymer dosage was 0.26% for primary sludge, 0.43% for secondary sludge and 0.38% for combined sludge. Contrary to the result of the thickening, the dewatering test revealed that dewatering of the combined sludge is better than that of separated sludge, representing better solids separation and filtrate quality. The polymer addition was essential to improve dewaterability in filter (belt) press type dewatering but it was inefficient for the dewatering of secondary sludge only. The centrifuge type dewatering showed better performance and the dewaterability was slightly improved when the polymer was added. Based on the results of this research a sustainable sludge treatment process, particularly in terms of the recycle water quality and solids recovery, was proposed.

• Korean Journal of Environmental Agriculture
• /
• v.12 no.3
• /
• pp.219-229
• /
• 1993

Effects of paper mill sludge-fertilizers were investigated on the growth performances of tree seedlings under field conditions. Two types of sludge-fertilizers applied were an organic sludge compost and a processed sludge-pellet fertilizer strengthened with several components of organic and inorganic nutrients. Three species of tree seedlings studied were ibota privet(Ligustrum obtusifolium) and yellow poplar(Liriodendron tulipifera) of 1-0 year seedlings and also eastern white pine(Pinus strobus) of 2-2 year seedlings. Nitrogen and phosphorus contents of plot soil treated with sludge compost+sludge-pellet fertilizer+sludge-pellet fertilizer plot were increased to 8 times and 2.6 times as those of control plot, respectively. The growth performances of root collar diameter and seedling height were repeatedly measured up to five times through the growing season and the results were analyzed statistically by analysis of variance of randomized block design and Duncan's multiple range test. The growth performances of dry weight were measured after last fifth measurements.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.8 no.3
• /
• pp.113-118
• /
• 1988

Laboratory aerobic and anaerobic digesters were operated to determine the nonbiodegradable fractions in PS (Primary Sludge) and WAS (Waste Activated Sludge)from a municipal wastewater treatment plant in Seoul. Nonbiodegradable fractions were determined to be 45 to 47% in PS and 58 to 68% in WAS. Ultimate $CH_4$ gas production rates were estimated to be 0.76 for PS and $0.54m^3/kg$ VS removed for WAS. $CH_4$ contents were respectively 63% for PS and 65% for WAS.

• Journal of Korea Water Resources Association
• /
• v.47 no.5
• /
• pp.483-490
• /
• 2014

The design procedures for a biological reactor and a secondary settling tank (SST) of an activated sludge system are based on the steady state design method (Ekama et al., 1986; WRC, 1984) and the 1-D flux theory design method (Ekama et al., 1997), respectively. This study combined both of the design procedures, to determine the optimum sludge concentration in the reactor and the best design with the lowest cost. The best design of the reactor volume and the SST diameter at the optimum sludge concentration were specified with varying wastewater and sludge characteristics, temperature, sludge retention time (SRT) and peak flow rate. The effects of the influent wastewater characteristics, such as substrate concentration and unbiodegradable particulate fraction, were found to be considerable, but the effect of unbiodegradable soluble fraction was to be negligible. The effects of sludge settling characteristics, were also significant. SRT, as an operating parameter, was found to be an important factor for determining the optimum sludge concentration. However, the effect of temperature was found to be small. Furthermore, for designing a large scale wastewater treatment plant, the number of reactors or SSTs could be estimated, by dividing the total reactor volume or SST area. The new combined design procedure, proposed in this research, will be able to allow engineers to provide the best design of an activated sludge system with the lowest cost.

• The Journal of the Korea Contents Association
• /
• v.9 no.10
• /
• pp.444-450
• /
• 2009

We have investigated biosorption kinetics and equilibrium of $Pb^2+$ and $Cr^2+$ using waste sludge, and separation efficiency of waste sludge by dissolved air flotation was evaluated in the various A/S ratio. The biosorption capacity and contact time were shown as a simulation of biosorption equilibrium and kinetics models. Biosorption equilibrium of the $Pb^2+$ and $Cr^2+$ onto the waste sludge could be fitted by the Langmuir, Freundlich, Redlich-Peterson, and Koble-Corrigan equation. The kinetics could be fitted by a pseudo-second-order rate equation more than a pseudo-first-order rate equation. The separation efficiency of waste sludge using DAF was kept above 90%.

• Journal of the Korea Organic Resources Recycling Association
• /
• v.25 no.1
• /
• pp.35-45
• /
• 2017

In order to improve the anaerobic digestion efficiency of the sewage sludge, the methane potential of the hydrolysate generated from the hydro-thermal reaction at 170, 180, 190, 200, 210, $220^{\circ}C$ was analyzed and the constitutional characteristics of the organic materials were estimated by dividing organic materials of hydro-thermal hydrolysate into easily biodegradable, decomposition resistant, and non-biodegradable organic materials applying the parallel first order kinetics model. The ultimate methane potential of sewage sludge hydro-thermal hydrolysate increased to 0.39, 0.39, 0.40, 0.44, 0.45, and $0.46Nm^3/kg-VS_{added}$ as hydro-thermal reaction temperature increased from 170, 180, 190, 200, 210, $220^{\circ}C$. It has been shown that the organic matter of sewage sludge is solubilized to increase the content of biodegradable organic material($VS_B$). The easily degradable organic matter($VS_e$) content was highest at hydro-thermal reaction temperature of 200 and $210^{\circ}C$, and optimum hydro-thermal reaction temperature for organic matter solubilization of sewage sludge was in the range of $200{\sim}210^{\circ}C$. In addition, the amount of biodegradable organic material($VS_B$) and easily biodegradable organic matter ($VS_e$) in the hydrolysate of sewage sludge was the highest at hydro-thermal reaction temperature of $200^{\circ}C$.

• Journal of the Korea Organic Resources Recycling Association
• /
• v.15 no.2
• /
• pp.89-97
• /
• 2007

In this study, thermalpretreatment was used to solubilize organic matter contained in sewage sludge before acid fermentation. By thermal pretreatment, solubilization of particulate CODcr, carbohydrate and protein increased. By thermal treatment at $120^{\circ}C$ for 30 minutes, CODcr solubilization efficiency of the primary sludge reached 8.3%. Meanwhile, for the secondary sludge, CODcr solubilization efficiency reached 16.5% because of high solubilization ratio of protein under the same pretreatment conditon. The results of anaerobic biodegradability test showed that both VFAs conversion ratio and hydrolysis rate of organic compounds in sewage sludge were improved by thermal pretreatment. Meanwhile, the optimum thermal pretreatment condition was varied with composition of organic compounds in sludge. In this study, the optimun thermal pretreatment condition of the primary sludge, containing high concentration of carbohydrate, was $80^{\circ}C$ for 30 minutes. Meanwhile, for the secondary sludge, mainly composed of protein, the sludge treated at $120^{\circ}C$ for 30 minutes showed the effective organic removal and VFAs production.

• Proceedings of the Korean Environmental Sciences Society Conference
• /
• 2003.05a
• /
• pp.92-96
• /
• 2003

1) 우리나라의 하수슬러지 해양투기량은 발생량의 73%를 상회하고 있으며 최근에 급증하는 추세에 있다. 2) 슬러지를 비롯하여 해양에 투기된 유해성분은 해양생물권 오염도 증가의 큰 요인으로 작용하고 있었다. 3) 해양에 투기된 하수슬러지가 침강하여 퇴적층을 형성하였을 때 저서생태계에 영향을 미칠 수 있는 가능성은 아주 높았다. 4) 슬러지의 중금속 화학형태 분석 결과 생물이 이용 가능한 중금속 비율이 원소에 따라 차이는 있으나 총 함량의 80% 이상을 차지하는 경우도 있었다. 5) 해양생물권의 오염도 증가, 유해성분에 의한 생태계의 악영향 및 투기된 중금속의 높은 생물 이용 가능성 등을 고려할 때 하수슬러지 처리방법의 전환이 필요하였다.

• Proceedings of the Korean Environmental Sciences Society Conference
• /
• 2007.05a
• /
• pp.339-345
• /
• 2007

이번 연구에서는 pH 조작이 어려운 소규모 하수 처리장에서의 BNR 슬러지의 접종으로 인한 SBR start-up시 영양 염류 제거 특성 및 변화를 관찰 하였다. 1) 글루코즈를 탄소원으로 사용한 유기물 제거에 있어서 모두 85%이상의 높은 제거 효율을 보였으나 BNR 슬러지 접종 비율이나 유무에 따른 SBR의 유기물 제거에 미치는 영향은 미비한 것으로 나타났다. 2) 유입비율에 따라 암모니아 제거 효율은 BNR 슬러지 첨가 유무에 따라 바뀌었으며, 비율에 상관없이 첨가된 반응조는 7일 이내 $82{\sim}98%$에 달하는 제거율을 보였다. 3) 인 제거효율에 있어서는 유입비율에 따라 인 제거 효율이 증가하였으며, 첨가와 미첨가의 차이는 25%이상의 인 방출량 차이를 나타내었다. 4) 첨가한 BNR 슬러지의 비율이 전체의 40%이상일 때는 50%일 때와 큰 차이를 보이지 못했다. 5) FISH를 통하여 미생물 군집을 확인하였고 각 미생물들 간의 상대적인 비율과 heterotroph의 급격한 증식을 확인할 수 있었다. 6) pH, DO, ORP graph를 통한 Reactor의 실시간 조정 가능성을 볼 수 있었다. 7) BNR 슬러지를 접종하지 않을 경우, PAOs와 질산화 미생물의 성장이 더뎌 영양염류 제거가 어려웠다.

• Journal of the Korea Organic Resources Recycling Association
• /
• v.10 no.3
• /
• pp.68-73
• /
• 2002

Acidogenic fermentation of primary sludge was investigated for the solution to reduce the sewage sludge and develope external carbon source for BNR process. In a viewpoint to use existing anaerobic digestion tanks, we didn't change environmental factors such as reactor configuration, temperature, pH and investigate the variation of solubilization rates, acidification rates and environmental factors which affected by the variation of HRT. The average solubilization rates were 0.0309 and $0.0204mgSCOD_{prod.}/mgICOD_{inf.}$ at a HRT of 3 and 1.5 days, respectively. The average acidification rates were 0.0068mg HAc/mg $TCOD_{inf.}$ and 0.0652mg HAc/mg $VSS_{destroyed}$ at a HRT of 3day. At a HRT of 1.5 days the average acidification rates were 0.0060mg HAc/mg $TCOD_{inf.}$ and 0.0346mg HAc/mg $VSS_{destroyed}$. For the period of experiments alkalinity and pH were properly maintained without artificial adjusting.