• Title/Summary/Keyword: sludge bulking

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Characteristics of Sludge Bulking Caused by Low Dissolved Oxygen in Aeration Tank for Paper Mill Wastewater Treatment (포기조의 낮은 용존산소로 인한 제지폐수의 슬러지 팽화특성)

  • Kwak, Dong-Heui;Yoo, Seung-Joon;Park, Jong-Chun
    • Journal of Korean Society on Water Environment
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    • v.24 no.4
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    • pp.458-464
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    • 2008
  • Bulking phenomena and scum formation are common problem in suspended growth system like the activated sludge plants for wastewater treatment. Apart from wastewater composition, operating conditions, such as mechanical stress by insufficient oxygen supply, are often decisive for the occurrence of a bulking or scumming problem. There were the comparative aeration tanks in terms of sludge bulking caused by the difference of mechanical aeration facilities in the wastewater treatment plant of N paper mill company. In this study the cause of bulking was investigated through not only the biological isolation and identification but also a series of operational data consideration. On the basis of the investigation results for bulking cause, the operational criteria on dissolved oxygen concentration was derived to decrease the bulking problem.

Fuzzy Expert System for Bulking Prediction and Mitigation in the Activeated Sludge Process

  • Nam, Sung-Woo;Kim, Jung-Hwan-;Sung, U-Kyung;Lee, Kwang-Soon-
    • Proceedings of the Korean Institute of Intelligent Systems Conference
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    • 1993.06a
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    • pp.1102-1105
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    • 1993
  • A fuzzy expert system for prediction and mitigation of sludge bulking was developed for an activated sludge process which treats waste water from a food industry. The developed system is able not only to infer the degree of progress of sludge bulking but also to generate remedial operation guides which may be sent to the local controllers as remote set points. One of the important consequences through this study is the BI (Bulking Index) inferred by the bulking prediction expert system was found to have a close correlation with the SVI (Sludge Volume Index) which is a practical measure of degree of bulking but needs tedious chores for its measurement.

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Chlorine Inhibition on the Denitrifying Activity of Activated Sludge Microorganisms (활성슬러지 미생물의 탈질 활성에 대한 염소의 저해)

  • Choi, Jin-Taek;Nam, Se-Yong
    • Journal of Environmental Health Sciences
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    • v.33 no.4
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    • pp.338-343
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    • 2007
  • Chlorine inhibition on the denitrifing activity of activated sludge treating dairy wastewater was investigated in this study. Filamentous bulking was caused artificially by a sudden load of feed and monitored by measuring sludge volume index. In cases of the activated sludge and bulking sludge which were contacted with chlorine as $7.5\;mgCl_2/gVSS/day$ for bulking control, the decreases of specific denitrification of $32.2{\sim}40.4%\;and\;43.5{\sim}46.5%$ were shown in comparison to the control group which was not reacted with chlorine, respectively. In continuous operation, it was observed that the removal efficiency of total nitrogen was more susceptible to chlorine than the removal efficiency of total phosphorus.

Membrane fouling and sludge characteristics in submerged membrane bioreactor under low temperature

  • Yuan, Yuan;Zhang, Jianqiao
    • Membrane and Water Treatment
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    • v.10 no.5
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    • pp.331-338
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    • 2019
  • This study aimed to investigate the membrane fouling and sludge characteristics in a pilot-scale submerged membrane bioreactor (MBR) operated under low temperature ($7^{\circ}C$). To elucidate the mechanisms of membrane fouling at low temperature, we studied the correlation between MBR performances and physicochemical properties of sludge including extracellular polymeric substance (EPS), relative hydrophobicity (RH) and floc size during long-term operation. The MBR was shown able to remove chemical oxygen demand (COD) stably and efficiently (>90 %) in the case of overgrowth of filamentous bacteria (bulking sludge) at low temperature. On the other hand, the occurrence of filamentous bulking greatly accelerated membrane fouling, as indicated by membrane filtration period of 14 days for filamentous bulking at $7^{\circ}C$, in comparison with that of 27 days for non-bulking sludge at $24^{\circ}C$ The overgrowth of filamentous bacteria resulting from low-temperature condition led to an increased release of EPS, higher RH, smaller floc size and lower fractal dimension of sludge. These factors accelerated the formation of compact cake layer on membrane surface in association with performance diminution in terms of increase in transmembrane pressure (TMP) of the membrane and thus the decrease in membrane permeability.

Effect of Sludge Characteristics on the Sedimentation of Bulking Sludge (팽화 슬러지의 침전에 미치는 슬러지 성상의 영향)

  • Kim, Dong-Seog;Park, Young-Seek
    • Journal of Environmental Science International
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    • v.15 no.12
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    • pp.1177-1183
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    • 2006
  • This study was carried out to evaluate effect of sludge characteristics (pH, SVI, anaerobic storage, wet density and growth phase) on the sedimentation of bulking sludge of paper manufacturing plant. The results showed that mix hulking sludge with sewage sludge (10-60%) caused the decrease of SVI, the settled sludge concentration was increased. Increase of anaerobic storage time (0 to 8 day) was increased SVI, sedimentation performance was deteriorated. The sedimentation was improved by addition of loess (0.2-5.0 g/L), because wet density of sludge was increased and SVI was decreased. At an exponential phase, the ratio of sedimented/growthed sludge concentration was decreased, the ratio was increased after stationary phase.

Vermistabilization of Organic Sludge (유기성 슬러지의 Vermistabilization)

  • 손희정;김형석;김수생;김용관
    • Journal of Environmental Health Sciences
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    • v.24 no.1
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    • pp.112-119
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    • 1998
  • The objective of this study was to investigate the effect of bulking agents including cow manure, saw dust and rice straw in the ripening of leather sludge for vermistabilization. The changes of the waste properties for ripening time for 50 days were observed according to the various mixture ratios of leather sludge and bulking agents. The pH values of the mixture wastes were decreased from 7.5-8.0 to 6.4-7.3 with the ripening time for 50 days, and it was indifferent of the mixture ratio and type of the bulking agent. The initial value of oxidation-reduction potential(Eh) of the mixture waste was a negative(-)value indicating an unfavorable condition for earthworm life, but the values of Eh were increased with the ripening time. The increase rate of Eh value was proportional to the mixture ratio of bulking agents, but the increase rate for saw dust was higher than that of the cow manure and the rice straw. The value of alkalinity was also changed into the favorable range for earthworm after 50 days except for 10% of the mixture ratio of the bulking agents. When the mixture ratios of the bulking agents were increased from 10% to 40%, the growth characteristics of earthworms were increased from 31.7% to 95% for the survival rate, 103% to 225% for the liveweight increase rate and 32% to 91% for hatching rate of the cocoons. It can be concluded that the proper content of the bulking agents in the leather sludge to ensure effective vermistabilization was over 30%, when the mixture was ripened during 50 days. The contents of heavy metals in the ripened sludge were lower than the other regulatory standards for compost.

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Effect of Chlorination for Bulking Control on the Organic Removal Activity of Activated Sludge Treating Dairy Wastewater (유가공 폐수의 활성슬러지 처리에서 벌킹 제어용 염소가 미생물의 유기물 분해 활성에 미치는 영향)

  • Nam Se-Yong;Choi Jin-Taek
    • 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.

Effect of Sludge Characteristics on the Thickening of Bulking Sludge using DAF (Dissolved Air Flotation) (슬러지의 성상이 DAF(Dissolved Air Flotation)를 이용한 팽화 슬러지 농축에 미치는 영향)

  • Kim, Dong-Seog;Park, Young-Seek
    • Journal of Korean Society on Water Environment
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    • v.22 no.1
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    • pp.97-103
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    • 2006
  • Excess sludge treatment and disposal currently represent a rising challenge for domestic or wastewater treatment plants due to economic, environmental and regulation factors. Conventional gravity sedimentation process has been widely used in sludge thickening. The operation method of the process is very simple, but the process requires long detention time for sludge thickening, uses polymers, and shows low sludge thickening efficiency. To solve the problems, we studied on DAF (Dissolved Air Flotation) system. We use bulking sludge of a paper manufacturing plant. The effects of parameters such as SVI (Sludge Volume Index), storage time, initial concentration and wet density of excess sludge were examined. The results showed that the more SVI was low, the more sludge was thickened. As storage time goes by, SVI was increased and thickening performance was deteriorated. In order to improve flotation performance at high concentration, high recycling ratio and pressure did not increase the concentration due to thickening limitation. The addition of 0.8 g/L of loess was increased flotation efficiency of 1.41 times.

An Investigation of the Causes of Filamentous Bulking at the Southerly Wastewater Treatment Plant in Columbus, Ohio (활성슬러지 하수처리장에서의 Filamentous Bulking의 원인규명을 위한 조사연구)

  • Ko, Kwang Baik;Sykes, Robert M.
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.7 no.3
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    • pp.77-87
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    • 1987
  • A series of bench scale activated sludge units were operated to find the causes of filamentous bulking(Schizothrix calcicola) at the Southerly Wastewater Treatment Plant. The results shows that the algal bulking problem is caused by the combination of fermented brewery waste and a low/high DO pattern in the aeration basin. The volatile fatty acids in the influent are not themselves the only cause of bulking but indicators of an unidentified substance that either suppresses zoogloeal growth or stimulates algal growth during low DO conditions, because the volatile fatty acids do not stimulate algal growth unless they are added to a sewage that already contains, some fermented brewery waste.

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Thickening of Bulking Sludge using DAF (Dissolved Air Flotation) (DAF(Dissolved Air Flotation)를 이용한 팽화 슬러지 농축)

  • Kim Dong-Seog;Park Young-Seek
    • Journal of Environmental Science International
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    • v.15 no.1
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    • pp.77-84
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    • 2006
  • An effective technique of sludge separation is required for excess sludge of sewage or wastewater plant. The separation of bulking sludge of paper manufacturing plant was studied using DAF(Dissolved Air Flotation) system. The effects of parameters such as nozzle type, A/S(air/solid) ratio. pressure, injection time of pressured water and saturation time were examined. The results showed that the best nozzle type was flat which had small orifice hole, The optimum A/S ratio and pressure were $7.070\times10^{-3}$(recycle ratio of pressured water $20\%$) and 5atm, respectively. Injection times of pressurized water around 20-25 sesc and flotation time of 30 min appeared to be optimal for the DAF operation. The order of performance of packing was 18 mm > 22 mm > 32 mm.