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Hydraulic retention time

About: Hydraulic retention time is a research topic. Over the lifetime, 6406 publications have been published within this topic receiving 151005 citations.


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Journal ArticleDOI
TL;DR: In this paper, anaerobic fluidized bed (AFBR) was used for the treatment of low strength wastes, such as municipal sewage, at low temperature, since the process is able to maintain a large mass of active microorganisms and provides effective removal of TSS.

66 citations

Journal ArticleDOI
TL;DR: In this article, two upflow anaerobic hybrid reactors treated lactose and a mixture of ethanol, propionate and butyrate, respectively, at a volumetric loading rate of 3.7 kg chemical oxygen demand (COD) m−3day−1, a hydraulic retention time of 5 days and a liquid upflow velocity of 0.01 m/h.
Abstract: Two upflow anaerobic hybrid reactors treated lactose and a mixture of ethanol, propionate and butyrate, respectively, at a volumetric loading rate of 3.7 kg chemical oxygen demand (COD) m−3day−1, a hydraulic retention time of 5 days and a liquid upflow velocity of 0.01 m/h. Under steady-state conditions, the lactose-fed sludge had much higher (20%–100%) specific methanogenic conversion rates than the volatile-fatty acid␣(VFA)/ethanol-fed sludge for all substrates tested, including VFA. In both reactors, a flocculant sludge developed, although a much higher content of extracellular polysaccharide was measured in the lactose-fed sludge [1900 μg compared to 305 μg uronic acid/g volatile suspended solids (VSS)]. When the liquid upflow velocity of a third, VFA/ethanol-fed reactor was increased to 0.5 m/h, granulation of the sludge occurred, accompanied by a large increase (200%–500%) in the specific methanogenic conversion rates for the syntrophic and methanogenic substrates studied. Granulation reduced the susceptibility of the sludge to flotation. Glucose was degraded at a high rate (100 mg glucose gVSS−1h−1) by the sludge from the third reactor, despite not having been exposed to a sugar-containing influent for 563␣days.

66 citations

Journal ArticleDOI
TL;DR: In this article, the performance of a fixed-bed UASB reactor exposed to intermittent aeration for the removal of organic matter and nitrogen from anaerobic reactor effluent was evaluated.
Abstract: This study evaluated the performance of a lab scale, fixed-bed reactor exposed to intermittent aeration for the removal of organic matter and nitrogen from anaerobic reactor effluent. The reactor was continuously fed with effluent from a UASB reactor used to treat wastewater from a poultry slaughterhouse. The hydraulic retention time (HRT) was maintained at 24 h during the five operational phases that the reactor was subjected to. The phases differed only for the duration of periods with and without aeration. The best results regarding nitrogen removal efficiency were obtained in phase V (8 daily cycles of 1 h of aeration and 2 h without aeration). Under these conditions, for influent with total COD of 418 mg L −1 , 169 mg L −1 of TKN and 112 mg L −1 of NH 4 + -N, effluent with a total COD of 22 mg L −1 , 6.4 mg L −1 of TKN, 6.4 mg L −1 of NH 4 + -N and 58 mg L −1 of NO 3 -N was obtained and NO 2 -N was not detected. During this phase, the average nitrogen removal efficiency was 62%. Optical microscopy and molecular biology analyses associated with the study of microbial activity detected the activity of bacteria that perform anammox, thereby contributing to the understanding of the processes involved.

66 citations

Journal ArticleDOI
TL;DR: The feasibility of the compartmentalized anaerobic migrating blanket reactor (AMBR) was studied for the treatment of low-strength soluble wastewater under low-temperature conditions and found that biomass was retained effectively and SCOD removal efficiencies staving greater than 70%.
Abstract: The feasibility of the compartmentalized anaerobic migrating blanket reactor (AMBR) was studied for the treatment of low- strength soluble wastewater under low-temperature conditions. During an operating period of 186 days, a 20-L AMBR was fed nonfat dry milk substrate as a synthetic wastewater at low temperatures (15 and 20 °C). The concentration of the influent was constant at chemical oxygen demand (COD) and 5-day biological oxygen demand (BOD5) concentrations of 600 and 285 mg/L, respectively. The soluble COD (SCOD) removal efficiency was 73% at the end of the operating period (15 °C) at a 4-hour hydraulic retention time (HRT), while the total COD (TCOD) removal efficiency was 59%. At a 4-hour HRT, staged conditions promoted complete removal of propionic acid in the final compartments of the reactor. The specific methanogenic activity of granules increased slowly until the end of the operating time, improving the removal rate. Biomass was retained effectively, as evidenced by the solids retention time (SRT) that was always greater than 50 days even during step decreases of the reactor HRT from 12 hours to 4 hours. A long SRT also promoted system stability during changes in flow, which was observed by SCOD removal efficiencies staying greater than 70%. During a hydraulic stress test, the HRT was reduced from 4 hours to 1 hour for one day (24 HRTs) in which volatile suspended solids (VSS) in the effluent increased from an average background level of 8.7 g/d to 35 g/d and the SRT decreased from 50.5 days to 12.6 days. However, mixed liquor volatile suspended solids concentration decreased only by 1 g/L, and hence a similar COD removal efficiency and biogas production was found one day after the hydraulic stress (as compared to one day before the hydraulic stress). Water Environ. Res., 73, 567 (2001).

66 citations

Journal ArticleDOI
TL;DR: Techno-economic analysis showed that the AO-AAR process is attractive and sustainable for municipal wastewater treatment by significantly improving nitrogen removal, greatly reducing land occupancy, enhancing methane production and achieving efficient reduction of carbon dioxide emission.

65 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023171
2022431
2021357
2020341
2019357
2018355