Showing papers on "Hydraulic retention time published in 2005"
TL;DR: No evidence of biodegradation for tetracycline was observed during the biodegradability test, and sorption was found to be the principal removal mechanism of tetrACYcline in activated sludge.
Abstract: A study was conducted to examine the influence of hydraulic retention time (HRT) and solid retention time (SRT) on the removal of tetracycline in the activated sludge processes. Two lab-scale sequencing batch reactors (SBRs) were operated to simulate the activated sludge process. One SBR was spiked with 250 μg/L tetracycline, while the other SBR was evaluated at tetracycline concentrations found in the influent of the wastewater treatment plant (WWTP) where the activated sludge was obtained. The concentrations of tetracyclines in the influent of the WWTP ranged from 0.1 to 0.6 μg/L. Three different operating conditions were applied during the study (phase 1HRT: 24 h and SRT: 10 days; phase 2HRT: 7.4 h and SRT: 10 days; and phase 3HRT: 7.4 h and SRT: 3 days). The removal efficiency of tetracycline in phase 3 (78.4 ± 7.1%) was significantly lower than that observed in phase 1 (86.4 ± 8.7%) and phase 2 (85.1 ± 5.4%) at the 95% confidence level. The reduction of SRT in phase 3 while maintaining a consta...
474 citations
TL;DR: In this paper, the performance of mesophilic anaerobic digesters of four large Italian wastewater treatment plants without primary sedimentation was studied, and a mathematical model for the prediction of biogas production on the solid retention time applied in the wastewater treatment process was developed.
329 citations
TL;DR: Results suggest that hydrogen yields will be optimized for more dilute feeds and lower organic loading rates than have typically been used in biohydrogen reactor studies.
250 citations
TL;DR: Aerobic granular sludge can successfully be cultivated in a sequencing batch reactor (SBR) treating dairy wastewater, and the maximum applicable loading rate is nevertheless limited, as the stability of aerobic granules very much depends on the presence of distinct feast and famine conditions.
Abstract: Aerobic granular sludge can successfully be cultivated in a sequencing batch reactor (SBR) treating dairy wastewater. Attention has to be paid to the fact that suspended solids are always present in the effluent of aerobic granular sludge reactors, making a post-treatment step necessary. Sufficient post-treatment can be achieved through a sedimentation process with a hydraulic retention time of 15–30 min. After complete granulation and the separation of biomass from the effluent, removal efficiencies of 90% CODtotal, 80% Ntotal and 67% Ptotal can be achieved at a volumetric exchange ratio of 50% and a cycle duration of 8 h. Effluent values stabilize at around 125 mg l−1 CODdissolved. The maximum applicable loading rate is nevertheless limited, as the stability of aerobic granules very much depends on the presence of distinct feast and famine conditions and the degradation of real wastewaters shows slower kinetics compared with synthetic wastewaters. As loading rate and volumetric exchange ratio are coupled in an SBR system, the potential of granular sludge for improving process efficiency is also limited.
230 citations
TL;DR: The characterisation of the soak liquor showed that this effluent is biodegradable, though not easily, and highly variable, depending on the origin and the nature of the hides, and the organisms responsible for nitrogen removal appeared to be the most sensitive to the modifications of these parameters.
186 citations
TL;DR: The applicability of the mixed bacterial culture, originated from two-stage anaerobic-aerobic industrial yeasts production wastewater treatment plant for high rate denitrification processes was investigated, obeying a zero- order reaction with respect to nitrate and a first-order reaction withrespect to biomass concentration.
184 citations
TL;DR: The experimental results indicated that effective hydrogen production from the food waste could be obtained continuously by thermophilic acidogenesis at proper operational condition.
Abstract: Conversion of food waste into hydrogen by thermophilic acidogenesis was investigated as a function of organic loading rate (OLR), hydraulic retention time (HRT) and pH in a continuous stirred tank reactor. In order to identify hydrogen-producing microorganisms, denaturing gradient gel electrophoresis (DGGE) of the polymerase chain reaction (PCR) – amplified V3 region of 16S rDNA analysis was conducted at each tested pH. The conversion of food waste into hydrogen was strongly influenced by the operational conditions. The hydrogen production was increased as OLR increased up to 8 gVSl-1 d-1, but drastically decreased at 10 gVSl-1 d-1. The yield of hydrogen was decreased from 2.2 to 1.0 mol-H2/mol-hexose consumed as HRT decreased from 5 to 2 days. More carbohydrates in the food waste were decomposed at longer HRT, 76–90%, at HRT of 2–5 days. The hydrogen production peaked at pH 5.5 ± 0.1 and significantly decreased at pH 5.0 ± 0.1. The biogas produced was composed of hydrogen and carbon dioxide, but no methane was detected at all tested conditions. The hydrogen contents in the gas produced were more than 55% (v/v) and not sensitive to all tested conditions. The optimum operational condition for continuous hydrogen production from the food waste was obtained at 8 gVSl-1d-1, 5 days HRT and pH 5.5 ± 0.1 where the hydrogen production rate, content, yield and the efficiency of carbohydrate decomposition were 1.0 l H2/l-d, 60.5% (v/v), 2.2 mol-H2/mol-hexose consumed and 90%, respectively. The hydrogen production was related with the concentration of total organic acids (TOA) which was strongly dependent on that of butyrate indicating that the reaction was mainly butyrate fermentation. The hydrogen-producing microorganism of Thermoanaerobacterium thermosaccharolyticum that involved in acetate/butyrate fermentation, was detected with strong intensity at all tested pHs by denaturing gradient gel electrophoresis (DGGE) of the polymerase chain reaction (PCR) – amplified V3 region of 16S rDNA analysis and sensitive to the tested pHs. The experimental results indicated that effective hydrogen production from the food waste could be obtained continuously by thermophilic acidogenesis at proper operational condition.
182 citations
TL;DR: In this paper, the performance of an expended granular sludge bed (EGSB) reactor coupled with hollow fibre membrane filtration for treating domestic wastewater was monitored during 7-month period in the range 11-25°C and at the hydraulic retention time (HRT) of 3.5 to 5.7
138 citations
TL;DR: A study on 18 full-scale centralized biogas plants was carried out in order to find significant operational factors influencing productivity and stability of the plants and ammonia was found to be a significant factor for stability.
131 citations
TL;DR: In this paper, a 6-L submerged anaerobic membrane bioreactor (SAMBaR) inoculated solely with the halotolerant sulfate reducing bacterium Desulfobacter halOTolerans was investigated in salt rich wastewaters.
130 citations
TL;DR: The results indicated that achieving high H2 productivity with nonsterile wastewaters will be challenging and membrane filtration of the recycle liquid may be required to exclude the return of hydrogen-consuming organisms.
Abstract: The effects of effluent recycle were examined in a two-phase anaerobic system where the first phase was operated for fermentative hydrogen production and the second for methanogenesis. The hydrogen reactor was operated as a chemostat at 35 °C and pH 5.5 with a 10 h hydraulic retention time, and the methane reactor was operated as an up-flow reactor at 28 °C and pH between 6.9 and 7.2. Two recycle ratios were examined: 0 and 0.98. Effluent recycle reduced the required alkalinity for pH control by approximately 40%. The H2 productivity metric, with a basis in electrons and incorporating both gaseous and dissolved H2, was developed as a more fundamental reporting method than the molar H2 yield. Without recycle, the H2 productivity was 0.115 g of H2 COD/g of feed COD, but decreased to 0.015 g of H2 COD/g of feed COD with recycle (COD = chemical oxygen demand). Mass balances indicated the lower H2 productivity during recycle was due to electrons being partitioned to methane and less-oxidized soluble constitue...
TL;DR: In this article, the authors evaluated the effect of four hydraulic retention times (HRT,0.3, 0.8, 2.3 and 9.3 days) on pollutant removal in a surface-flow wetland system for polishing tertiary effluent from a sewage treatment plant.
Abstract: We evaluated the effect of four hydraulic retention times (HRT, 0.3, 0.8, 2.3, and 9.3 days) on pollutant removal in a surface-flow wetland system for polishing tertiary effluent from a sewage treatment plant (STP). The removal efficiency of pollutants at these HRTs was based on mass budgets of the water inputs and outputs in parallel ditches, which together with a presettling basin, made up the wetland system. Fecal coliform and N-removal efficiencies in the ditches were enhanced by increasing the HRT, with only little removal of fecal coliforms during spring-summer at a HRT of 0.3 days. A HRT of 4 days turned out to be required to meet the desired bathing water standard for fecal coliforms (10 3
TL;DR: In this paper, anaerobic fermentation of corn stover by rumen microorganisms in both batch and semi-continuous cultures was studied, and the experimental results demonstrate that the anaerobically fermented maize stover was able to rapidly degrade the volatile solids and produce useful VFAs with high yields.
TL;DR: In this paper, the performance of an upflow anaerobic sludge blanket (UASB) reactor treating wastewater with volatile fatty acids (VFA) and alcohol generated during hydrogen fermentation of food waste was investigated.
TL;DR: In this paper, the authors considered the anaerobic fermentation of source-sorted organic municipal solid wastes in psychrophilic conditions (14−22 °C) without pH control.
Abstract: After investigating the application of the mesophilic and thermophilic processes in completely stirred, batch, and plug-flow reactors, in this study the authors consider the anaerobic fermentation of source-sorted organic municipal solid wastes in psychrophilic conditions (14−22 °C) without pH control. The pilot-scale reactor was operated in a batch mode, with a hydraulic retention time of 4−4.5 d. The production of soluble COD from the particulate matter was (on average) 0.27 gCOD per gram of total volatile solids fed to the reactor when operating with a total solids content of 20−35 g/L. The volatile fatty acids (VFA) were 15% of the soluble COD produced after 4 d of reaction. These values are far lower than those found in mesophilic and thermophilic conditions, where the production of soluble COD ranged from 0.5 up to 0.9 gCOD/gTVSfed and volatile fatty acids could reach 90% of soluble COD. Further, the first-order reaction constant for the hydrolysis process, Kh, for the psychrophilic conditions was f...
TL;DR: A fluidized zero valent iron (ZVI) reactor is examined for nitrate reduction and results indicate the probable formation of nitrogen gas species during reaction in pH4.0.
TL;DR: In this paper, an up-flow anaerobic filter reactor fed with olive mill wastewaters (OMWs), reliable parameters that could suggest process imbalance were determined, including a decrease in biogas production and methane yield together with an accumulation of VFAs such as acetate, propionate, butyrate, isobutyrate and valerate.
TL;DR: In this article, a lab-scale anaerobic sequencing batch reactor (ASBR) was used to characterize and treat wastewater from olive mills in Jordan, with an average COD:N:P ratio of about 900:5:1.
TL;DR: In this paper, a suspended carrier biofilm reactor was investigated for its capability of carbon oxidation and nitrification, where the carrier used was polyvinyl chloride cylinder with 2.5-3.0mm height.
TL;DR: In this paper, the effect of increasing dye loadings from 6.1 to 213.0 gm −3 ǫh −1 on decolorization and COD removal efficiency was investigated at constant glucose-COD concentrations in an UASB reactor.
TL;DR: It was concluded that an inoculum from cow manure added with nutrients and yeast extract allowed a 95% removal of BOD5 from poultry slaughter wastewater at ambient temperatures within a hydraulic residence time of 4 h, sharply reducing possible environmental hazards.
TL;DR: In this paper, two immobilization methods were employed, biofilm formation on poly vinyl alcohol (PVA) and granulation of the sludge with cationic and anionic polymers.
TL;DR: In this article, the up-flow anaerobic sludge blanket (UASB) and sequencing batch reactor (SBER) were used for the treatment of Orange II-containing wastewater.
TL;DR: In this paper, a two-year study was used to identify significant water quality parameters and to develop a predictive nonlinear model to estimate the corrosivity of blends based on water quality.
Abstract: The implementation of groundwater conservation measures has forced utilities with a historical reliance on groundwater sources to consider alternative sources to augment their supplies or to eliminate their groundwater dependence. Switching from traditional source water, however, can cause unacceptable changes in water quality that result from destabilization and the release of chemical and biological films from the interior surfaces of the existing distribution systems. Data from a two-year study were used to identify significant water quality parameters and to develop a predictive nonlinear model to estimate the corrosivity of blends based on water quality. The results of the statistical analysis indicate that alkalinity, chlorides, sulfates, sodium, and dissolved oxygen of the source water or blend of source waters have a significant effect on release of corrosion by-products in the form of red water. Temperature and hydraulic retention time were the significant physical and operational parameters identified.
TL;DR: In this paper, the performance of the sequencing anoxic/anaerobic membrane bioreactor process (SAM) was investigated in a pilot-scale experiment, where the constant flux was maintained and the variation of the transmembrane pressure was monitored to evaluate the membrane fouling.
TL;DR: In this paper, the authors evaluated the effectiveness of constructed wetland for treatment of this woodwaste leachate, which was characterized by high oxygen demand, tannin and lignin, and volatile fatty acids (VFAs), but low pH and nutrients.
TL;DR: A surface-flow wetland system designed for polishing effluent from a sewage treatment plant (STP) on the island of Texel, The Netherlands, was studied between April 1996 and March 1997 as discussed by the authors.
Patent•
03 May 2005TL;DR: In this article, a method and process for the treatment of wastewater containing phosphorous and nitrogen was proposed, where wastewater is first anaerobically treated to produce an anaerobic effluent from which insoluble organic carbon is separated to form a sludge rich in organic carbon.
Abstract: A method and process for the treatment of wastewater containing phosphorous and nitrogen. The wastewater is first anaerobically treated to produce an anaerobic effluent from which insoluble organic carbon is separated to form a sludge rich in organic carbon that is used as a substrate during anoxic treatment of the wastewater by de-nitrifying phosphorous accumulating organisms (DPAO's) and ordinary de-nitrifying organisms. The separation of insoluble organic carbon is normally conducted using a clarifier located intermediate the anaerobic and anoxic bio-reactors. In one embodiment, the ammonia rich clarifier supernatant is directed to an aerobic reactor for nitrification and the nitrate produced is recycled to the anoxic bio-reactor. The final effluent may be membrane filtered to retain nitrifying biomass within the aerobic bio-reactor. The invention reduces overall hydraulic residence time and sludge volume, which results in a smaller, less expensive wastewater treatment system.
TL;DR: In this article, a novel anaerobic hybrid reactor (AHR) configuration incorporating floating support media for biomass immobilization and biogas recirculation for enhanced mixing was used for anaerob digestion of dairy manure No pretreatment or solid liquid separation was applied.
Abstract: A novel anaerobic hybrid reactor (AHR) configuration incorporating floating support media for biomass immobilization and biogas recirculation for enhanced mixing was used for anaerobic digestion of dairy manure No pretreatment or solid liquid separation was applied The reactor was operated at high influent volatile solids (VS) and organic loading rates (OLR) of up to 987% and 730 g VS/l day, respectively After 149 days of continuous operation the results revealed that a high amount (381 g VSS) of biomass was able to attach itself to the support medium being used The investigated AHR configuration achieved COD, BOD, TS, and VS removal efficiencies of 48–63, 64–78, 55–65, and 59–68%, respectively, at a hydraulic retention time (HRT) of 15 days The corresponding average methane production value obtained in this study was 0191 l/g VS added