Showing papers on "Hydraulic retention time published in 1999"
TL;DR: In this paper, the performance of an anaerobic/anoxic/aerobic (2+2+12h of hydraulic retention time) process with and without inoculation of sodium chloride acclimated seeds was investigated using a synthetic wastewater with COD, nitrogen, and phosphorus of 500, 25, and 15 µm, respectively.
159 citations
TL;DR: In this article, the influence of temperature, flow rate and input concentrations on the treatment efficiency of organic matter and nutrients in constructed wetlands (CWs) is discussed, and three integrated 10 PE systems with horizontal subsurface flow (HSF) treating domestic wastewater are described.
121 citations
TL;DR: In this article, an innovative process for removing heavy metals including Cu, Ni and Zn from industrial wastewater has been developed based on inducing the nucleated precipitation of heavy metals on the sand surface in a fluidized bed reactor.
109 citations
TL;DR: In this article, the effects of ionic chromium, cadmium, lead, copper, zinc, and nickel on the methanogenic UASB granule were examined by using serum bottle assays.
108 citations
TL;DR: In this article, the authors examined the influence of support media on biomass growth and retention and their resulting impact on system performance and failure in an upflow anaerobic filter system.
103 citations
TL;DR: In this paper, the use of an anaerobic baffled reactor (ABR) and effect of different pH, temperatures, hydraulic retention times and organic loading rates on continuous ANE digestion of black liquor from pulp and paper mills was reported.
94 citations
TL;DR: In this paper, the authors used activated sludge units for high-rate nitrification of high load wastewater at full scale, with a hydraulic retention time of 1.3 h and 20°C.
92 citations
TL;DR: Investigation of the effects of hydraulic retention time (HRT), the presence or absence of supplemental substrate and variation in feed concentration on the biodegradation potential of 2,4-dichlorophenoxyacetic acid found that changes in the feed concentration did not produce a significant effect on theBiodegradation behavior of 2.4-D.
86 citations
TL;DR: In populations dominated by Pseudomonas pseudoalcaligenes, high denitrification rates were obtained even at oxygen concentrations as high as 5 mg l −1 and in populations dominated of B. niacini, these populations showed however a limited efficiency with respect to nitrite reduction.
81 citations
TL;DR: In this article, a laboratory scale membrane aeration bioreactor (MABR) with a void volume of 1.35 l was tested for its ability to treat synthetic wastewater, and the ability of the reactor to operate under plug flow conditions demonstrated that the biofilm plays a significant role in oxygen mass transfer.
72 citations
TL;DR: In this paper, the performance of an expanded granular sludge bed (EGSB) reactor for treating slaughterhouse wastewater under mesophilic conditions (35°C) was investigated.
TL;DR: In this article, the effects of the filter media properties, effective grain size, specific surface area, pH and cation exchange capacity were examined for loading rates of 25 mm and 50 mm/day applied as 8 doses per day.
TL;DR: Metal ions acted as a strong competitor against the organic compounds for active sites on the bioflocs instead of acting as a toxic microbial inhibitor, thus hampering organic adsorption and affecting the COD removal efficiency under shorter HRTs.
TL;DR: In this paper, two bench-scale completely mixed bioreactors were used to investigate the effect of potato-processing industrial wastewater on the acidogenesis of primary sludge and found that the addition of the starch-rich potato processing wastewater considerably improved the performance of the system, resulting in an increase in the net VFA and soluble chemical oxygen demand (COD) concentrations and corresponding specific production rates.
TL;DR: A municipal wastewater biosludge was acclimated to the degradation of 4-nitroaniline (4-NA), and batch tests showed, that 3-NA can serve as the sole source of carbon, nitrogen and energy.
TL;DR: In this article, a laboratory-scale hybrid UASB reactor was used for the treatment of distillery spentwash, which used anaerobically digested sewage sludge as a seed, the start-up of the reactor and the cultivation of active granular sludge was completed within three months period.
Abstract: A laboratory-scale hybrid UASB reactor, which combined an UASB in the lower part and a filter in the upper part, was used for the treatment of distillery spentwash. The reactor was operated under ambient conditions for 380 days. Using anaerobically digested sewage sludge as a seed, the start-up of the reactor and the cultivation of active granular sludge was completed within three months period. Scanning electron microscopic (SEM) observation of the granules showed the presence of Mehtanonthrix-like bacteria as the dominant species. Following the start-up the organic loading rate (OLR) was increased, stepwise, to 36 kg COD/m3 · d at a constant hydraulic retention time (HRT) of 6 h. COD removal efficiency was 80% even at a high OLR of 36 kg COD/m3 · d. Biogas rich in methane content (80%), with a maximum specific biogas yield of 0.40 m3 CH4/kg · COD was produced. Polypropylene pall rings filter medium in the upper-third of the reactor was very effective as a gas-liquid-solid (GLS) separator, and retained the biomass in addition. The study indicated that hybrid UASB is a very feasible alternative for the treatment of high-strength wastewaters like distillery spentwash.
TL;DR: In this article, a system consisting of primary sedimentation tank, anaerobic treatment using UASB-reactors, aeration tanks using attached growth reactor and oxidation ponds system was investigated.
TL;DR: In this article, a simple mathematical model was set up to describe digestion performance adequately designating the process conditions for most effective turnover, based on kinetic data of a one stage digester.
TL;DR: The feasibility of thermophilic (55°C) anaerobic sulphur removal from partly acidified wastewater was investigated using two 6.5-l upflow anaerobe sludge bed (UASB) reactors and introduction of N2 as an additional strip-gas into R1 resulted in an almost complete H2S removal.
Patent•
13 Jul 1999
TL;DR: In this paper, a process for the biological treatment of waste water containing ammonia is described, where the waste water is treated with sludge containing nitrifying bacteria in an aerated reactor, applying a sludge retention time in the reactor which favours nitrite-producing bacteria over nitrate-consuming bacteria.
Abstract: A process is described for the biological treatment of waste water containing ammonia, wherein the waste water is treated with sludge containing nitrifying bacteria in an aerated reactor, applying a sludge retention time in the reactor which favours nitrite-producing bacteria over nitrate-producing bacteria. The process is characterised by applying a hydraulic retention time in a continuously operated reactor, which is shorter than the sludge retention time as a result of part of the sludge being separated from the reactor effluent and being returned to the reactor. The performance of the nitrification is further improved by applying low oxygen and nitrite concentrations.
TL;DR: In this paper, the determination of a kinetic model in an anaerobic digestion process is dealt with, which is applied to the organic stabilization of the solid fraction of piggery slurry.
Abstract: This work deals with the determination of a kinetic model in an anaerobic digestion process. It is applied to the organic stabilization of the solid fraction of piggery slurry. The substratum results after filtering the farm wastewaters through a 1 mm mesh hydraulic sieve. Two pilot scale reactors were used, one digester was working in layered way — without agitation — and other was mixed with a stirrer. The experiments were carried out in a discontinuous process, 60 days hydraulic retention time, in the mesophilic interval (35°C). Average influent concentration was 68 and 97 g l −1 COD respectively for the non-stirred and stirred reactor, whereas the achieved reduction was 61 and 65%. Organic loading rates were 0.80 and 1.45 K VS m −3 d −1 . Specific biogas output was more efficient in the stirred reactor than in the stratified one. Several kinetic models were tried out in order to represent the methane production. A first order kinetic model applied in two stages was finally adapted for both reactors. The first stage presented the microbial growing as the limiting step, whereas the second stage was limited by the substratum availability. The effect of mixing on the kinetic parameters was analyzed. Significant differences were attained in the coefficients, thus K was 0.048 and 0.75 d −1 respectively for the non-stirred and stirred reactor.
TL;DR: In this article, a 10 1 anaerobic fluidized bed reactor (AFBR) was designed and constructed, using beach sand as the solid support for the biomass, achieving a COD removal of over 85%, for an OLR of 3.4 [kg COD/m3·d].
TL;DR: Results indicate that the EGSB potentials can be further explored for the anaerobic treatment of low-strength brewery wastewater, even at lower temperatures.
Abstract: Anaerobic treatment of low-strength brewery wastewater, with influent total chemical oxygen demand (COD) (CODin) concentrations ranging from 550 to 825 mg/L, was investigated in a pilot-scale 225.5-L expanded granular sludge bed (EGSB) reactor. In an experiment in which the temperature was lowered stepwise from 30 to 12 degrees C, the COD removal efficiency decreased from 73 to 35%, at organic loading rates (OLR) of 11-16.5 g COD/L/d. The applied hydraulic retention time (HRT) and liquid upflow velocity (Vup) were 1.2 h and 5.8 m/h, respectively. Under these conditions, the acidified fraction of the CODin varied from 45 to 90%. In addition to the expected drop in reactor performance, problems with sludge retention were also observed. In a subsequent experiment set at 20 degrees C, COD removal efficiencies exceeding 80% were obtained at an OLR up to 12.6 g COD/L/d, with CODin between 630 and 715 mg/L. The values of HRT and Vup applied were 2.1-1.2 h, and 4.4-7.2 m/h, respectively. The acidified fraction of the CODin was above 90%, but sludge washout was not significant. These results indicate that the EGSB potentials can be further explored for the anaerobic treatment of low-strength brewery wastewater, even at lower temperatures.
TL;DR: In this article, an autotrophic denitrification process with elemental sulphur to achieve a high quality effluent with a low concentration of total N was tested at laboratory scale, and two types of wastewater were tested during a period of 10 months.
Abstract: An autotrophic denitrification process with elemental sulphur to achieve a high quality effluent with a low concentration of total N was tested at laboratory scale. Two types of wastewater were tested during a period of 10 months. One was a multiple household wastewater obtained from a municipal wastewater treatment plant and the other was a single household wastewater collected from a family. The wastewaters were first treated by primary sedimentation, followed by nitrifying trickling filtration. The nitrified effluents from the trickling filter were further denitrified in an autotrophic denitrification stage. The autotrophic denitrifying reactor was filled with a mixture of elemental sulphur powder and small pieces of limestone. Sulphur was used as an electron donor and CaCO3 in the limestone served as pH buffer. With a hydraulic retention time of 2–3 hours, up to 86 % of total oxidizable nitrogen (TON) was removed from the multiple household wastewater and 75 % from the single household wastewater. The...
TL;DR: The feasibility of anaerobic digestion of poultry slaughterhouse wastes combined with wastes from a food packing plant was studied using semi-continuously fed, laboratory-scale, continuously-stirred digesters at 35 °C and 55 °C.
Abstract: The feasibility of anaerobic digestion of poultry slaughterhouse wastes combined with wastes from a food packing plant was studied using semi-continuously fed, laboratory-scale, continuously-stirred digesters at 35 °C and 55 °C. Furthermore, factors affecting anaerobic digestion were studied using batch assays with digested material from the digesters. In the mesophilic digester, inoculated with mesophilic digester sewage sludge, and with a loading of up to 4.6 g volatile solids (VS) l−1 d−1 (a hydraulic retention time (HRT) of 18 days), the specific methane yield was 330 ml g−1 VSadded. Nitrogen in the feed was organic nitrogen with a slight amount of ammonium present, while ammonium nitrogen in the digested material accounted for 50 to 70 % (up to 3.9 g l−1) of total nitrogen. The total solids and VS removals were 58 and 68 %, respectively. With the highest loading, however, methane production was apparently curtailed at the end of the study period, and sustainability of a long-term operation of the pro...
TL;DR: In this article, a new approach to solubilization of excess activated sludge by self-digestion was studied to reduce the amount of sludge produced in the activated-sludge-treatment process.
TL;DR: Methane was formed even under these conditions, indicating that the aerobic and facultative microorganisms limited the O2 penetration and maintained a reduced microenvironment which was necessary for the methanogens to function.
TL;DR: The suitability of two stage biomethanation process using upflow anaerobic sludge blanket (UASB) bioreactors was studied for the treatment of low strength industrial effluents like rice mill wastewater as discussed by the authors.
Abstract: The suitability of two stage biomethanation process using upflow anaerobic sludge blanket (UASB) bioreactors was studied for the treatment of low strength industrial effluents like rice mill wastewater. Maximum VFA yield was 0.75 mg (as acetic acid) per mg of COD consumed at a flow rate of 25 ml/min. Hydraulic retention time (HRT) of 1 hr was found suitable for acidification process. In the methanogenic reactor, the overall BOD and COD reductions were 89% and 78% respectively at loading rate of 3 kg COD m−3 d−1, and HRT of 30 hrs. Gas yield in methanogenic reactor was 0.56 lits. per kg COD consumed which contains 62% v/v methane.
TL;DR: A sequencing batch biofilm reactor (SBBR) was developed to treat dilute formulated rinsate of atrazine [2-chloro-4-(ethylamino),6-(isopropylamino)-s-triazine] from an agricultural chemical formulation facility as discussed by the authors.
TL;DR: In this paper, the authors examined the performance of a four-compartment fixed-film system in which the biofilm is attached to submerged ceramic tiles under diffused aeration, known as the aerated submerged fixed film (ASFF) process.