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COD Removal (cod + removal)
Terms modified by COD Removal Selected AbstractsAssessment of anaerobic wastewater treatment failure using terminal restriction fragment length polymorphism analysisJOURNAL OF APPLIED MICROBIOLOGY, Issue 6 2005C. Scully Abstract Aims:, The suitability of genetic fingerprinting to study the microbiological basis of anaerobic bioreactor failure is investigated. Methods and Results:, Two laboratory-scale anaerobic expanded granular sludge bed bioreactors, R1 and R2, were used for the mesophilic (37°C) treatment of high-strength [10 g chemical oxygen demand (COD) l,1] synthetic industrial-like wastewater over a 100-day trial period. A successful start up was achieved by both bioreactors with COD removal over 90%. Both reactors were operated under identical parameters; however, increased organic loading during the trial induced a reduction in the COD removal of R1, while R2 maintained satisfactory performance (COD removal >90%) throughout the experiment. Specific methanogenic activity measurements of biomass from both reactors indicated that the main route of methane production was hydrogenotrophic methanogenesis. Terminal restriction fragment length polymorphism (TRFLP) analysis was applied to the characterization of microbial community dynamics within the system during the trial. The principal differences between the two consortia analysed included an increased abundance of Thiovulum - and Methanococcus -like organisms and uncultured Crenarchaeota in R1. Conclusions:, The results indicated that there was a microbiological basis for the deviation, in terms of operational performance, of R1 and R2. Significance and Impact of the Study:, High-throughput fingerprinting techniques, such as TRFLP, have been demonstrated as practically relevant for biomonitoring of anaerobic reactor communities. [source] Effect of inhibitory compounds on the anaerobic digestion performance of diluted wastewaters from the alimentary industryJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 11 2009Rafael Camarillo Abstract BACKGROUND: Up to now the effect of inhibitory compounds on the anaerobic digestion performance of urban and industrial wastewaters has been mostly studied in fluidized bed and upflowing anaerobic sludge blanket (UASB) bioreactors but not in upflow packed-bed biodigesters. RESULTS: In this paper, response surface methodology (RSM) was used to quantify the effect of various inhibitory compounds (olive oil, ethanol and phenol) on chemical oxygen demand (COD) removal and biogas production rate from synthetic solutions and real industrial wastewaters by anaerobic digestion. The synthetic solutions possessed the same composition in these inhibitory compounds as diluted effluents from olive oil mill and winery industries. The process was performed in a laboratory scale digester containing anaerobic sludge from the Urban Reclamation Station of Toledo (Spain). The comparison of both individual factors and interactions between factors showed that the addition of olive oil at moderate concentrations (up to 0.5% w/w) did not change the performance of the process in comparison with that observed when feeding to the system a model solution (51.5% COD removal, 0.65 L biogas day,1). However, low concentrations of ethanol or phenol (250 and 150 mg L,1, respectively) almost completely inhibited the methanogenic phase. Moreover, a strong interaction between ethanol and phenol concentrations on COD removal was observed. CONCLUSION: The experimental results showed quantitatively the importance of some inhibitory compounds on anaerobic treatment of both synthetic solutions and real wastewaters from olive oil mill and winery industries. Inhibitory effects are closely related to both the organic loads and the anaerobic bioreactor used. Copyright © 2009 Society of Chemical Industry [source] Ozonation of complex industrial park wastewater: effects on the change of wastewater characteristicsJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 7 2009Jen-Mao Fanchiang Abstract BACKGROUND: Ozonation of complex industrial park wastewater was carried out in a semi-batch reactor. The variation of wastewater characteristics was evaluated based on the analysis of 5-day biochemical oxygen demand (BOD5) concentration, BOD5/chemical oxygen demand (COD) ratio, COD fractionation, and dissolved organic carbon (DOC) molecular size distribution before and after ozonation. RESULTS: The experimental results indicated that low efficiency of COD removal with increasing tendency of BOD5 concentration generally appeared after ozonation. Also, the BOD5/COD ratio increased from an initial of 0.27 to a maximum of 0.38. The COD fractionation tests revealed that most of the inert soluble COD was transformed to biodegradable soluble COD at 30 min of reaction time. Additionally, the DOC molecular size distribution tests showed that the fraction larger than 500 kDa was significantly decreased and the fraction smaller than 2 kDa was increased when the reaction time was prolonged to 240 min. CONCLUSION: This study verified that partial oxidation of the complex industrial park wastewater by ozonation could enhance wastewater biodegradability. The biodegradability enhancement was primarily because the inert soluble COD fraction was converted to the biodegradable soluble COD and the high molecular weight fraction of DOC was shifted toward the low molecular weight fraction. Copyright © 2009 Society of Chemical Industry [source] Enhancement in mineralization of some natural refractory organic compounds by ozonation,aerobic biodegradationJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 2 2006Devendra P Saroj Abstract Two schemes, the first involving ozonation followed by final aerobic biodegradation (phase I experiments), and the second involving initial aerobic biodegradation, followed by ozonation and subsequent final aerobic biodegradation (phase II experiments), were examined for enhanced mineralization of refractory model compounds, viz. gallic acid, tannin and lignin. In all cases, and irrespective of the applied scheme, chemical oxygen demand (COD), total organic carbon (TOC), COD/TOC ratio, and specific UV absorbance at 280 nm attributed to the model compounds decreased with application of increasing ozone dose. The residual organic matter remaining after ozonation exhibited enhanced aerobic biodegradability in all cases. Further, in all cases and irrespective of the applied scheme, the overall amount of COD and TOC removed through the combination of ozonation and biodegradation processes increased with increase in ozone dose for all three model compounds, and more than 90% COD removal could be achieved with an ozone dose of 3 mg ozone absorbed per mg initial TOC, as compared with approximately 40% COD removal when no ozone was applied. Treatment by the first scheme resulted in the fraction of starting COD removed through biodegradation decreasing with increase in ozone dose in all cases, while this fraction increased or remained constant during treatment using the second scheme. In the case of tannin and lignin, similar overall COD removal could be achieved at lower ozone doses using scheme II. Due to incorporation of the initial aerobic biodegradation step in scheme II, the ozone requirement for additional mineralization, ie mineralization over and above that achieved by aerobic biodegradation, was also lower than that in scheme I. Copyright © 2005 Society of Chemical Industry [source] Development of a membrane-assisted hybrid bioreactor for ammonia and COD removal in wastewatersJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 2 2005Vinka Oyanedel Abstract A new membrane-assisted hybrid bioreactor was developed to remove ammonia and organic matter. This system was composed of a hybrid circulating bed reactor (CBR) coupled in series to an ultrafiltration membrane module for biomass separation. The growth of biomass both in suspension and biofilms was promoted in the hybrid reactor. The system was operated for 103 days, during which a constant ammonia loading rate (ALR) was fed to the system. The COD/N-NH4+ ratio was manipulated between 0 and 4, in order to study the effects of different organic matter concentrations on the nitrification capacity of the system. Experimental results have shown that it was feasible to operate with a membrane hybrid system attaining 99% chemical oxygen demand (COD) removal and ammonia conversion. The ALR was 0.92 kg N-NH4+ m,3 d,1 and the organic loading rate (OLR) achieved up to 3.6 kg COD m,3 d,1. Also, the concentration of ammonia in the effluent was low, 1 mg N-NH4+ dm,3. Specific activity determinations have shown that there was a certain degree of segregation of nitrifiers and heterotrophs between the two biomass phases in the system. Growth of the slow-growing nitrifiers took place preferentially in the biofilm and the fast-growing heterotrophs grew in suspension. This fact allowed the nitrifying activity in the biofilm be maintained around 0.8 g N g,1 protein d,1, regardless of the addition of organic matter in the influent. The specific nitrifying activity of suspended biomass varied between 0.3 and 0.4 g N g,1 VSS d,1. Copyright © 2004 Society of Chemical Industry [source] Membrane bioreactors vs conventional biological treatment of landfill leachate: a brief reviewJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 10 2004Héctor Alvarez-Vazquez Abstract A review of quality and biological treatment of landfill leachate is presented. Conventional ex-situ treatment normally demands multistage process treatment schemes, which may encompass both aerobic and anaerobic technologies alongside chemical precipitation and/or oxidation. This is to be contrasted with the more recent membrane bioreactor technology, which generally demands much reduced pre- and post-treatment and has a much reduced footprint compared with conventional biotreatment. Results are summarised in terms of the key determinant of COD removal for waters characterised in terms of BOD/COD ratio and age. Process operation is characterised with respect to COD strength and loading rate, hydraulic retention time and number of individual unit operations. Copyright © 2004 Society of Chemical Industry [source] Treatment of textile dye wastewater by using an electrochemical bipolar disc stack reactorJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 10 2004Karuppan Muthukumar Abstract Textile dye house wastewater from a reactive dye processing unit was treated by using an electrochemical oxidation technique. The experiments were carried out in an electrochemical bipolar disc reactor using RuO2 coated on titanium as anode and titanium as cathode. The sodium chloride present in the effluent was used as supporting electrolyte. Operating parameters such as current density, reservoir hold-up and electrolysis time were studied for maximum Chemical Oxygen Demand (COD) reduction and other relevant parameters such as current efficiency and power consumption per kg of COD removal were calculated. The higher flow rate and lower reservoir hold-up resulted in improved COD removal. The applied current density was also found to significantly influence the reduction of COD. A suitable mathematical model is also proposed to illustrate the relationship between the basic parameters. Pseudo mass transfer coefficients were also evaluated for different experimental conditions. Copyright © 2004 Society of Chemical Industry [source] Addition of activated carbon to batch activated sludge reactors in the treatment of landfill leachate and domestic wastewaterJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 8 2001Özgür Akta Abstract Leachate from a municipal landfill was combined with domestic wastewater and was treated in batch activated sludge systems. The effectiveness and applicability of the addition of Powdered Activated Carbon (PAC) to activated sludge reactors was investigated. Isotherm tests were carried out with PAC in order to estimate the extent of adsorption of organic matter onto PAC. Then, in activated sludge reactors COD (Chemical Oxygen Demand) removal and nitrification were studied both in the absence and presence of PAC for comparison purposes. In both cases, Oxygen Uptake Rates (OUR) were measured with respect to time in order to investigate substrate removal and change in microbial activity. Addition of PAC to activated sludge increased COD removal by removing mainly the non-biodegradable fraction in leachate. The COD decreases in batch reactors were best expressed by a first-order kinetic model that incorporated this non-biodegradable leachate fraction. With added PAC, nitrification was also enhanced. But in all of the batch runs a significant accumulation of NO2 -N took place, indicating that the second step of nitrification was still inhibited. © 2001 Society of Chemical Industry [source] Use of various processes for pilot plant treatment of wastewater from a wood-processing factoryJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 3 2001Nikolaos S Athanasopoulos Abstract The wastewater from a wood-processing factory is characterized by a high COD, chlorides and nitrogen content. Various treatment processes were applied to treat this wastewater in pilot-scale units. By applying one-stage denitrification,activated sludge biological treatment it was not possible to remove nitrogen. Nitrification was inhibited by wastewater compounds. By applying a second stage of a nitrification biofilter it was possible to have a high degree of nitrification. The denitrification was complete. With biological methods the reduction of COD, and -N and -N concentrations to acceptable values was not achievable. Physical,Chemical methods as H2O2/UV, electrolysis and ozonation were used as post-treatment of effluents from the biological system. Radical degradation, initiated by the powerful hydroxyl radicals which are generated from H2O2 by UV activation, is used for wastewater post-treatment. The combination of H2O2/UV was not suitable for post-treatment of this wastewater. With electrolysis, -N and COD removal can be complete. The total amount of ammonia and organic nitrogen converted to nitrate nitrogen for current density of 1.15,Adm,2 and energy consumption of 71.6,kWhm,3 was 0.35,gdm,3. Further biological denitrification is required for -N removal to permitted values. Energy consumption for the elimination of 1,kg COD was 40.4,kWh and 35.8,kWh for current densities of 0.7,Adm,2 and 1.15,Adm,2 respectively. The energy required to reach the limit value of COD equal to 150,mgdm,3 for current density of 1.15,Adm,2 was 71.6,kWhm,3. With ozonation, the COD removal can be complete. Further biological nitrification,denitrification is required to remove -N and -N to permitted values. At pH 7.0, in order to reach the limit value of COD equal to 150,mgdm,3, specific ozone dose was 6.0,g per g of COD removed and the total amount of ammonia and organic nitrogen converted to nitrate nitrogen was 0.25,gdm,3. The total equivalent energy required is estimated to be 75.0,kWhm,3. © 2001 Society of Chemical Industry [source] Development of a mechanistic model for biological nutrient removal activated sludge systems and application to a full-scale WWTPAICHE JOURNAL, Issue 6 2010Bing-Jie Ni Abstract In wastewater treatment plants (WWTPs) the production of nitrite as an intermediate in the biological nutrient removal (BNR) process has been widely observed, but not been taken into account by most of the conventional activated sludge models yet. This work aims to develop a mechanistic mathematical model to evaluate the BNR process after resolving such a problem. A mathematical model is developed based on the Activated Sludge Model No.3 (ASM3) and the EAWAG Bio-P model with an incorporation of the two-step nitrification,denitrification, the anoxic P uptake, and the associated two-step denitrification by phosphorus accumulating organisms. The database used for simulations originates from a full-scale BNR municipal wastewater treatment plant. The influent wastewater composition is characterized using batch tests. Model predictions are compared with the measured concentrations of chemical oxygen demand (COD), NH -N, NO -N, NO -N, PO -P, and mixed liquid volatile suspended solids. Simulation results indicate that the calibrated model is capable of predicting the microbial growth, COD removal, nitrification and denitrification, as well as aerobic and anoxic P removal. Thus, this model can be used to evaluate and simulate full-scale BNR activated sludge WWTPs. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] Improvement in biomass characteristics and degradation efficiency in modified UASB reactor treating municipal sewage: a comparative study with UASB reactorASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 5 2009Suprotim Das Abstract Low strength wastewaters (LSWs) are difficult to degrade efficiently in the upflow anaerobic sludge blanket (UASB) reactor. The possible reasons for poor treatment of LSWs in UASB are: (i) low mixing due to low biogas production (ii) frequent biomass washout at higher hydraulic loading rate due to low settleability of biomass. In the present study, lab scale UASB reactor and modified upflow anaerobic sludge blanket (MUASB) reactor were operated with municipal sewage containing chemical oxygen demand (COD) in range of 180,210 mg L,1 as LSW at three different hydraulic retention times (HRTs) of 8, 6, and 4 h. The changes in the biomass characteristics as well as degradation efficiency were compared with respect to time. During this operation, samples of biomass were taken from both reactors to measure total suspended solids (TSS), settling velocity, granular size and specific methanogenic activity (SMA). The overall COD removal in MUASB reactor was higher compared to UASB (84 and 67% respectively). After 150 days of operation, the settling velocity and SMA of MUASB biomass increased, but no significant change in settling velocity and SMA of UASB biomass was observed. The study shows that MUASB could be preferred over UASB for the treatment of municipal sewage as LSW. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source] Performance of Dual-Media Expanded Bed BioreactorASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 5-6 2005R. Abdul-Rahman Abstract Adsorption and biological treatment are two possible approaches to remove chloro-organic and organic compounds. Granular activated carbon (GAC) biofilm reactors combine these two features, the adsorptive capacity and irregular shape of GAC particles providing niches for bacterial colonisation protected from high fluid forces, while the variety of functional groups on the surface enhance the attachment of microorganisms. The biofilm process is compact and offers reactions in both aerobic and anoxic states. Studies on removal of nitrogen constituents by a biofilm process were carried out using a dual-media expanded bed bioreactor, with GAC and plastic media as support media. The plastic media also acts as a filter for the effluent. Experiments were carried out at F:M of about 0.45 and hydraulic residence times (HRT) of 48, 24 and 12 hours. Bed expansion was maintained at 20,30% by recirculation flow. Aerobic condition was maintained at dissolved oxygen (DO) of about 2 mg/l throughout the bed. Chemical oxygen in demand (COD) in feed was 1000 mg/L while the total-N was 100 mg/L. Analysis showed that the process is able to maintain very stable conditions, achieving substantial COD removal of about 85% and total-N removal of about 80%. Biofilm biomass measurements showed an increase from 400 mg/l at HRT of 48 hours to 10,100 mg/l at HRT 12 hours, showing that much higher biomass concentrations may be contained in a biofilm process as compared to a conventional suspended biomass process. Bioreactors contain their own ecosystems, the nature of the community and the state of microorganisms define the kinetics and determine reactor performance. Growth kinetic parameters obtained are YH = 0.3421 mg/mg, m,H = 0.2252 day,1, KH = 319.364 mg/l and bH = 0.046 day,1. The denitrification kinetic parameters obtained are YHD = 0.9409 mg/mg, m,HD = 0.1612 day,1, KHD = 24.6253 mg/l and bHD = 0.0248 day,1. These parameters enable prediction of required reactor sizes and operational parameters. The plastic media has greatly improved effluent clarification by 98% as compared to single-media (GAC) only reactor. [source] Estimation of Biological Kinetic Parameters from a Continuous Integrated Ozonation-Activated Sludge System Treating Domestic WastewaterBIOTECHNOLOGY PROGRESS, Issue 6 2000Fernando J. Beltrán The feasibility of treating municipal wastewater by a combined ozone-activated sludge continuous flow system was studied. Lab-scale experiments of both single activated sludge and combined ozone-activated sludge processes were carried out to determine the kinetic coefficients of the biological stage. The results obtained indicated a clear improvement in the kinetic parameters of the aerobic oxidation when a pre-ozonation stage was applied. Particularly, COD removal and nitrification rates were highly increased. The biokinetic parameters were also used to simulate and optimize the continuous reaction system. From the model prediction it was concluded that the integrated process (i.e., ozone-ASP) may significantly increase the waste reduction capacity. The results presented here provide a useful basis for further scaling up and efficient operation of ozone-ASP units in wastewater treatment processes. [source] Phenol Removal through Chemical Oxidation using Fenton ReagentCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 5 2007Y. Yavuz Abstract In this study, phenol, aromatic, and non-biodegradable organic matter were investigated and found to be removed from the model solution through chemical oxidation using Fenton reagent. The effects of the initial phenol concentration, hydrogen peroxide, and ferrous sulfate concentrations on the removal efficiency were investigated. Performance of the chemical oxidation process was monitored with phenol and COD (Chemical Oxygen Demand) analyses. In the experimental studies, phenol removal of over 98,% and COD removal of nearly 70,% were achieved. The optimum conditions for Fenton reaction both for initial phenol concentrations of 200 and 500,mg/L were found at a ratio [Fe2+]/[H2O2] (mol/mol) equal to 0.11. According to the results, chemical oxidation using Fenton reagent was found to be too effective, especially for phenol removal. However, this method has limited removal efficiency for COD. [source] Indirect Electrochemical Oxidation of Phenol in the Presence of Chloride for Wastewater TreatmentCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 1 2005D. Rajkumar Abstract Electrochemical oxidation of phenol using a Ti/TiO2 -RuO2 -IrO2 anode in the presence of chloride as the supporting electrolyte was investigated. The experiments were performed in an undivided batch reactor. Preliminary investigations showed that only a small fraction of phenol was oxidized by direct electrolysis, while complete degradation of phenol was achieved by indirect electrochemical oxidation using chloride as a supporting electrolyte. The effect of operating parameters such as initial pH, supporting electrolyte concentration, phenol concentration, and charge input was studied using Box-Behnken second order composite experimental design. The effect of current density on COD removal was studied separately. TOC removal and AOX formation were studied for selected conditions. It was found that the formation of chlorinated organic compounds was pronounced at the beginning of electrolysis, but it was reduced to lower levels by extended electrolysis. 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