• Journal of the Korean Society of Industry Convergence
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• v.15 no.3
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• pp.83-86
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• 2012

This study have cross checked the change of internal sludge-recycle in Full-scale Anaerobic-Digestion, and researched about not only the improvement of Bio-gas production from the digested sludge but also the efficient method of sludge minimization. Ultimate aim of the study is to reduce the amount of sludge by the improved efficiency of contact with the organic-matter and the microbes in Anaerobic-Digestion. The sludge-recycle fluidized sludge layer and raised the activity of the sludge, The sludge-recycle ratio of optimum was 500%, VS and COD removal ratio respectively appeared with 67.8% and 70.4%. Through these result of this study, it may be positive view to treat waste sludge by the sludge-recycle ratio in terms of minimization and circulation of resources.

• Journal of Environmental Science International
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• v.23 no.6
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• pp.1061-1066
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• 2014

This study has cross checked the change of internal sludge-recycle in Anaerobic-Digestion, and researched about not only the improvement of Bio-gas production from the digested sludge but also the efficient method of sludge minimization. Ultimate object of the study is to reduce the amount of sludge by the improved efficiency of contact with the organic-matter and the microbes in Anaerobic-Digestion. The sludge-recycle fluidized sludge layer and raised the activity of the sludge, the optimal sludge-recycle ratio, VS and COD removal ratio were 1,000%, 28.2% and 27.7%, respectively. Through these results of this study, it may be of use to treat waste sludge by the sludge-recycle ratio in terms of minimization and circulation of resources.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.1
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• pp.88-96
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• 2006

Among the various methods for minimization of waste activated sludge, maintaining a low F/M ratio in the bioreactor is known to be the most effective reliable one. In this research, various experiments were performed to check the capability of the nonwoven fabric filter bioreactor, which has been proved able to maintain a low F/M ratio by maintaining a high MLSS concentration, for excess sludge minimization. The reactor was intermittently fed with a synthetic wastewater having a COD concentration of approximately 300 mg/L and no SS. Results of the experiments showed that the F/M ratio in the reactor decreased to a minimum value of 0.02 g COD/g MLSS-day as the MLSS concentration increased to a maximum value of 31,010 mg/L. However, the measured endogenous decay coefficients and oxygen uptake rates of the MLSS confirmed that the activity of the MLSS decreased as the MLSS concentration increased. Based on the increase of MLSS in the reactor and the mass balance during the whole experimental period, the average microorganism yield coefficients were computed to be low values of 0.148 and 0.139 g MLSS/g COD, respectively. These results indicate that the nonwoven fabric filter bioreactor employed in this research is effective for minimization of excess sludge production.

• Journal of Environmental Science International
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• v.18 no.6
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• pp.675-682
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• 2009

Sludge minimization from wastewater treatment plant is becoming more important to save disposal costs and to contribute to sustainable development. For the reduction of sludge production, solubilization and dewaterability of sludge are important factors in sludge processing. Ultrasonic treatment has been used to enhance sludge solubility and dewaterability with anaerobic digestion sludge, primary sludge, and activated sludge. At the ultrasonic power of 0.2 kW/L for 1 hour, anaerobic sludge and activated sludge showed higher solubilization efficiency than the primary sludge in terms of COD, proteins, and suspended solids. Ultrasonic treatment decreased sludge dewaterability and sludge settling characteristics up to 720 kJ/L of ultrasonic energy. In conclusion, ultrasonic treatment was effective for sludge solubilization but it deteriorate dewaterability (specific resistance) and settling characteristics (SVI) of sludge at the experimental conditions.

• Journal of the Korea Organic Resources Recycling Association
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• v.2 no.1
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• pp.87-98
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• 1994

Sludge minimization in an water treatment plant can be achieved by optimizing a main water treatment process as well as by enhancing a thickening and a dewatering facilities. In this study, dewatering and drying techniques for reducing the quantity of the water sludge generated from the conventional water treatment plant in the local states were investigated by reducing its water content. Not only the types and dosages of polymers but also the mixing intensity of the mixtures of a concentrated sludge and polymers on the different pH were evaluated for the optimum dewatering conditions of the water sludge. Weight reduction of the water sludge was also tested at a given temperature range. The dewatering efficiency of the water sludge was not affected by the types of polymer but by mixing intensity(GT value) in this study. pH effect on dewaterbility of the water sludge took a major role at the neutral pH range. The optimal polymer dose was 1.5 mg-polymer/g-TSS(about 40mg/L as polymer). Dewaterability was enhanced at a lower mixing intensity(GTbelow 10,000 sec-1). Free water in the void of sludge cake was dried around $100^{\circ}C$, chemical bound water was evaporated around $320^{\circ}C$, and organic material was burned out at the range of 300 to $600^{\circ}C$. Ignition losses of the water sludge were varied 15 to 40 % as the raw water quality. The ignition loss due to the chemical bound water was 10-20% and the loss due to the organic material was 4-20% of the total ignition loss.

• Journal of Microbiology and Biotechnology
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• v.12 no.4
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• pp.683-686
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• 2002

To achieve optimum operation of a thermophilic aerobic digestion (TAD) process for waste activated sludge (WAS), TAD experiments using Bacillus stearothermophilus (ATCC 31197) were carried out to investigate the optimum concentration of dissolved oxygen (DO). TAD reactors were operated at DO concentrations of 0, 1, 2, 3, 4, and 5 ppm, and the results showed that the WAS could be successfully degraded by a TAD system operated with a DO concentration of 1 ppm and above. When the TAD system with an optimum additive (2 mM Ca ion), selected from a previous study, and 1 ppm DO concentration were combined with a thermal pretreatment ($121^{\circ}C$, 10 min), the results exhibited upgraded total suspended solids and an enhanced protein degradation.

• Journal of Korean Society of Water and Wastewater
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• v.28 no.2
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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 %.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.3
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• pp.304-310
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• 2007

The purpose of this research was to investigate the effects of the co-treatment of municipal wastewater with microwave-irradiated excess sludge on the treatment efficiency and excess sludge production of the activated sludge process. When 250 mL of excess sludge with a MLSS concentration of approximately 2,000 mg/L was microwave-irradiated at $20^{\circ}C$ for $40\sim300$ sec by a microwave oven (2,450 MHz, 700 W), the temperature of the sludge increased at a rate of approximately $20^{\circ}C/min$ and the SCOD, TKN and T-P concentrations of the sludge showed the highest increase in the irradiation time of $40\sim130$ sec. And, the oxygen uptake rate measurement of the sludge microorganism suggested most of the microorganisms in the sludge were destroyed at an irradiation time above 130 sec(above $65^{\circ}C$). When the municipal wastewater and microwave-irradiated excess sludge was co-treated by the activated sludge process, almost no effect was observed in the pH and alkalinity of both the influent and effluent, but the influent concentrations of SS, COD, T-N and T-P increased. Even though the effluent SS, BOD and T-P concentrations showed almost no effect, the COD and TKN concentrations increased. The microbial yield coefficient decreased at a rate of 0.91 g SS/g COD removed as the irradiation ratio increased at a rate of 1 g SS/g SS-day.

• Journal of the Korea Organic Resources Recycling Association
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• v.12 no.2
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• pp.52-60
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• 2004

The basic approach to sewage sludge is organic waste minimization, promotion of energy recovery; volume and weight reduction by final treatment, and environmentally final disposal of natural circulation. Dry and pyrolysis of maize was experimentally investigated in full-scale rotary kiln in semi-continuous operation. The operational parameters varied are the operating temperature $160{\sim}175^{\circ}C$ of dry and $450{\sim}800^{\circ}C$ of pyrolysis, the solids residence time 9 min for pyrolysis. Important parameters studied include the running time, water content of sewage sludge, solids amount of sewage sludge(TS%) by the varied temperature. Also, with the increasing of temperature, how the yield of oil and char product change was observed, and the distribution of gas production components was observed. The gas of $C_1{\sim}C_3$ yield increased and oil of $C_4{\sim}C_6$ yield decreased along with pyrolysis temperature of $670^{\circ}C$ by the run time of 9 min.

• Environmental Analysis Health and Toxicology
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• v.18 no.3
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• pp.193-197
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• 2003

슬러지로부터 발생하게 되는 인체에 유해하고 독성이 강한 악취물질들은, 대다수 슬러지내의 단백질, 탄수화물등의 물질들이 미생물의 호기성 및 혐기성 분해과정을 통해서 생성되는 유ㆍ무기 물질들을 포함하게 된다. 슬러지로부터 발생하는 주된 악취물질로서 hydrogen sulfide, methanethiol, dimethyl sulfide, dimethyldisulfide,dimethyltrisulfide등이 발견되어졌는데 이 다섯 종의 악취물질들은 모두가 황을 포함하는 물질들이다. 본 논문에서는 인체에 유해한 슬러지 악취의 강도 및 세기를 결정하고 비교하는 데 이용되어 질 수 있는 odor index(ODI)라는 방식이 제시되어졌다. 세가지 종류의 슬러지, 즉 hypochlorite 용액으로 처리한 슬러지와 향수 물질로 처리한 슬러지 및 아무런 처리를 하지 않은 슬러지 세 종류를 대상으로 30일이 넘는 기간동안 인체에 유해한 악취물질들에 대한 누적 odor index(ODI)값을 생성하여 비교하였다. 아무런 처리를 하지 않은 슬러지에서 가장 높은 odor index(ODI)값들이 나타났으며, 이것은 슬러지 처리에 있어서 심각한 단기 및 장기적인 유해 악취발생 문제가 야기될 수 있음을 나타낸다. 이에 대하여 hypochlorite용액으로 처리한 슬러지로부터는 인체에 유해한 악취 발생을 처리 즉시부터 30일이 넘는 기간동안 측정한계치 이하 단계로 낮출 수 있었다.