• Title, Summary, Keyword: COD reduction

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Evaluation of COD Solubilization and Reduction of Waste Activated Sludge by pH Control (pH 조절을 통한 폐활성 슬러지의 COD 가용화 및 감량화 평가)

  • Kim, Youn Kwon;Moon, Yong Taik;Kim, Ji Yeon;Seo, In Seok
    • Journal of Korean Society of Water and Wastewater
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    • v.21 no.5
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    • pp.551-558
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    • 2007
  • From the view point of biological wastewater treatment, C/N ratio is one of the most important factor in biological nutrient removal process. However, municipal sewage in Korea is characterized by extremely low content of carbon source and relatively higher portion of N source. Accordingly, it is necessary to dose external carbon source in order to obtain higher degree of carbon source within the process. In this study, the effects of pH pretreatment as an alternative plan for increasing carbon source on the cell disruption and COD solubility of waste activated sludge were conducted under well defined experimental conditions. During 5 hours, the value of COD solubilization rate ($S_R$) at pH 11.5 is approximately 4.4 times higher than the value of $S_R$ at pH 9.5. It is expected that the level of SCOD increased due to the result from cell disruption. However, VSS/TSS ratio was not significantly changed after 5 hours. As Alkalinity changes gradually from less than 15, 30 and 60 meq NaOH/L, average RBCOD/SCOD fraction showed 34, 36 and 45%,respectively.

A novel nanocomposite as adsorbent for formaldehyde removal from aqueous solution

  • Hejri, Zahra;Hejri, Mehri;Omidvar, Maryam;Morshedi, Sadjad
    • Advances in nano research
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    • v.8 no.1
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    • pp.1-11
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    • 2020
  • In order to develop a new adsorbent for removal of formaldehyde from aqueous solution, surface modification of TiO2 nanoparticles was performed with 2,4-Dinitrophenylhydrazine (DNPH) that have a strong affinity to the formaldehyde. Sodium dodecyl sulfate (SDS) surfactant was used to improve the DNPH grafting to TiO2 surface. Modified adsorbents were characterized by SEM, TEM, XRD, EDX and FTIR. Since the COD level in wastewaters including formaldehyde is considerable, it is necessary to determine the COD content of the synthetic wastewater. In order to determine the optimal removal conditions, the effect of contact time (60-210 min), pH (4-10) and adsorbent dosage (0.5-1.5 g/L) on adsorption and COD removal efficiencies were studied, using response surface method. EDX and FTIR analysis confirmed the presence of nitrogen-containing functional groups on the modified TiO2 surface. The maximum formaldehyde adsorption and COD removal efficiencies by modified TiO2 were about 15.65 and 7.35% higher than the unmodified nanoparticles respectively. Therefore, the grafting of nano-TiO2 with DNPH would greatly improve its formaldehyde adsorption efficiency. The optimum conditions determined for a maximum formaldehyde removal of 99.904% and a COD reduction of 94.815% by TiO2/SDS/DNPH nanocomposites were: adsorbent dosage 1.100 g/L, pH 7.424 and the contact time 183.290 min.

Water Quality Management of Kwangyang Bay by Point Pollution Source Control (점원 오염부하 제어에 의한 광양만의 수질관리)

  • Lee Dae-In;Park Chung-Kil;Cho Hyeon-Seo
    • Journal of the Korean Society for Marine Environment & Energy
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    • v.4 no.3
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    • pp.28-39
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    • 2001
  • The eco-hydrodynamic model was used to simulation water quality of Kwangyang Bay according to the environmental variation for appropriate water quality management. The mean concentration of COD was 3.3㎎/L, this exceeded the third class of water quality criteria. Waste water discharging loads showed approximately 90% of total pollutant loads. For satisfaction to below 10㎍/L of Chl. a and 2㎎/L of COD, above 35% reduction of present pollutant loads of point sources are needed.

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Electric power generation from treatment of food waste leachate using microbial fuel cell

  • Wang, Ze Jie;Lim, Bong Su
    • Environmental Engineering Research
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    • v.22 no.2
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    • pp.157-161
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    • 2017
  • Simultaneous treatment of food waste leachate and power generation was investigated in an air-cathode microbial fuel cell. A TCOD removal efficiency of $95.4{\pm}0.3%$ was achieved for an initial COD concentration of 2,860 mg/L. Maximum power density ranged was maximized at $1.86W/m^3$, when COD concentration varied between 60 mg/L and 2,860 mg/L. Meanwhile, columbic efficiency was determined between 1.76% and 11.07% for different COD concentrations. Cyclic voltammetric data revealed that the oxidation peak voltage occurred at -0.20 V, shifted to about -0.25 V. Moreover, a reduction peak voltage at -0.45 V appeared when organic matters were exhausted, indicating that reducible matters were produced during the decomposition of organic matters. The results showed that it was feasible to use food waste leachate as a fuel for power generation in a microbial fuel cell, and the treatment efficiency of the wastewater was satisfied.

Treatment of produced water in a floating carrier bioreactor

  • Ezechi, Ezerie Henry;Sapari, Nasiman;Menyechi, Ezerie Jane;Ude, Clement M.;Olisa, Emmanuel
    • Environmental Engineering Research
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    • v.22 no.2
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    • pp.210-215
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    • 2017
  • Produced water is the largest wastestream of oil and gas exploration. It consists of various organic and inorganic compounds that hinder its beneficial use. This study compared the treatment of produced water in a batch suspended and biofilm activated sludge process. The biofilm carrier material was made from Gardenia Carinata shell. COD, $NH_4{^+}-N$ and $NO_3-N$ removal was monitored in both the suspended (control) and floating carrier bioreactors. The results show a rapid reduction of produced water constituents in the floating carrier bioreactor. COD, $NH_4{^+}-N$ and $NO_3-N$ removal was in the range of 99%, 98% and 97% for the floating carrier bioreactor whereas it was 88%, 84% and 83% for the control bioreactor. The rapid reduction of COD, $NH_4{^+}-N$ and $NO_3-N$ clearly indicate that the floating carrier materials served as an attached growth medium for microorganisms, improved the breakdown of produced water constituents and reduced inhibition of microbial metabolic activities.

Biological Treatment of Dyeing Wastewater Using Jet Loop Reactor with Activated Carton Supports (활성탄 담체가 포함된 Jet-Loop Reactor를 이용한 종합염색폐수처리)

  • 조무환;박종탁;이길호;류원률
    • KSBB Journal
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    • v.17 no.3
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    • pp.241-246
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    • 2002
  • Today, many problems of dye-processing wastewaters were raised due to industry of dyeing and textiles. It is difficult to treat them perfectly because they contain many poorly degradable matters, such as surfactants, ethylene glycol, polyvinyl alcohol, and so on. To improve the performances of conventional physicochemical treatment and activated sludge process, new systems of combining jet-loop reactor (JLR) with physicochemical treatment were developed. Volumetric oxygen transfer coefficient ($k_{L}a$) of JLR was significantly larger than that of air-lift reactor. Also, for the effective treatment of dye-processing wastewater, JLR with active carbon supports (JLRAS) were investigated. Removal efficiency of BOD, $COD_{Mn}$, $COD_{Cr} and color were found as 99, 86, 84, 83%, respectively, when HRT was 8 hrs. And performance of JLRAS was rapidly restored after step change of $COD_{Mn}$ loading late. The optimal coagulant and dosage of second physicochemical treatment after JLRAS were polyferric sulfate and 130 mg/L, respectively, when removal efficiencies of $COD_{Mn} and color were 85 and 73%, respectively. In conclusion, this system enables the reduction of operation cost, and the effective removal of many organics.

Nitrogen and Phosphorus Removal in Domestic Wastewater using SBR Process with Flow Changing Continuous Feed and Cyclic Draw (교대연속유입식 SBR 공정을 이용한 하수중의 질소 및 인 제거)

  • Seo, In-seok;Kim, Hong-suck;Kim, Youn-kwon;Kim, Ji-yeon
    • Journal of Korean Society on Water Environment
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    • v.22 no.2
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    • pp.203-208
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    • 2006
  • A continuous feed and cyclic draw SBR process was developed to overcome flow rate fluctuation and to maximize organic matters utilization efficiency for nitrogen and phosphorus removal. The developed SBR process was operated with two parallel reactors. Influent was supplied to one reactor which was not obligately aerated. At the same time, the other reactor was just aerated without supplying influent. In addition this mode was changed periodically. Cycle time was 6hr and aeration time ratio($t_{aer}/t_{total}$) was 0.33, respectively. $COD_{cr}$ and SS removal efficiencies of 95% or higher were achieved. Nitrogen removal was so greatly influenced by influent $COD_{cr}/T-N$ ratio. At influent $COD_{cr}/T-N$ ratio of 5.7, removal efficiencies of ammonia-N, T-N and T-P were 96%, 78% and 55%, respectively. Influent $COD_{cr}/T-N$ of 4 or higher ratio was necessary to achieve 60% or higher nitrogen removal. Organic matters of influent was efficiently utilized in denitrification reaction and consumed COD has a good correlation with removed T-N(about 6.5 mgCOD/mgTN). Continuous feed and cyclic draw SBR process could be one of alternative processes for the removal of nutrients in rural area where $COD_{cr}/T-N$ ratio was low and fluctuation of flow rate was severe.

A Study on the Reduction of COD, Total Phosphorus and Nitrogen in Wastewater by Electrolysis and HClO Treatment (전기화학처리와 HClO 처리를 통한 폐수중 COD, 총인, 총질소의 저감에 대한 연구)

  • Kim, Tae Kyeong;Song, Ju Yeong
    • Journal of the Korean Applied Science and Technology
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    • v.34 no.3
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    • pp.436-442
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    • 2017
  • This study was conducted to develop a wastewater treatment system to remove organic matter, nitrate nitrogen, and phosphate ion in synthetic wastewater. COD was removed almost 100% by the oxidation reaction of HClO and nitrate nitrogen was reduced to ammonia by electrolysis treatment, but ammonia was reoxidized into nitrate nitrogen by HClO treatment. Ammonia was removed almost 100% by heating evaporation and no ammonia was reoxidized into nitrate by HClO treatment. Phosphate ion could be removed by precipitation treatment by forming metal complex according to pH. Through electrolysis treatment and HClO treatment, removal efficiencies of COD 99.5%, nitrogen 97.3% and phosphorus 91.5% were obtained.

Combination of air stripping and biological processes for landfill leachate treatment

  • Smaoui, Yosr;Bouzid, Jalel;Sayadi, Sami
    • Environmental Engineering Research
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    • v.25 no.1
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    • pp.80-87
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    • 2020
  • Landfill waste decomposition generates a dark effluent named, leachate which is characterized by high organic matter content. To minimize these polluting effects, it becomes necessary to develop an effective landfill leachate treatment process. The objective of this study was to evaluate the performance of an innovative approach based on air stripping, anaerobic digestion (AD) and aerobic activated sludge treatment. A reduction of 80% of ammonia and an increase of carbon to nitrogen ratio to 25 were obtained, which is a suitable ratio for AD. This latter AD was performed in fixed bed reactor with progressive loading rate that reached 2 and 3.2 g COD/L/d for the raw and diluted leachate (1:2), respectively. The anaerobic treatment led to significant removal of chemical oxygen demand (COD) and biogas production, especially for the diluted leachate. The COD removal was of 78% for the raw leachate and a biogas production of 4 L/d with 70% methane content. The use of the diluted leachate led to 81% of COD removal and 7 L/d biogas with 75% methane content. It allowed a removal of 77% COD and more than 97% of the organic compounds present in the initial leachate sample.

A Study on the Treatment of Wastewater from the Weight-Reduction Process of Polyester (폴리에스테르 감량가공(減量加工) 폐수(廢水)의 최적(最適) 처리방안(處理方案)에 관한 연구(硏究))

  • Chung, Yoon Jin;Yang, Tae Du;Kim, Woong Ha
    • Journal of Korean Society of Water and Wastewater
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    • v.7 no.1
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    • pp.20-28
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    • 1993
  • The Wastewater from the weight reduction process of polyester is more difficult to be treated biologically than the general wastewater from dyeing and finishing processes in textile industries. Above wastewater shows high pH, high organic strength and wide variation of organic loading. These characteristics are due to TPA and EG resulting from alkaline weight-reduction process and make trouble in the operation of activated sludge process. Therefore, the objective of this study is to develop the pretreatment method for the successful operation of treatment process. For the successful pretreatment process, the wastewater from weight-reduction process should be segregated from other wastewater stream and then acidified with concentrated sulfuric acid to precipitate out TPA from DST solution. At the optimum pH of 2. 2, the initial $COD_{cr}$ 60,000mg/l is reduced to 11,500mg/l and the removal efficiency of $COD_{cr}$ is 81.1%. The required amount of sulfuric acid for pretreatment is not greater than the amount for the the existing neutralization process. Moreover, the supernatant of pretreatment process can be reused in acidification of wastewater.

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