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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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TL;DR: In this paper, over 160 publications related to fermentative hydrogen production from wastewater and solid wastes by mixed cultures are compiled and analyzed, including pre-treatment conditions for screening hydrogen-producing bacteria from anaerobic sludge or soil, and the process and performance parameters for (2) single substrates in synthetic wastewaters, (3) actual wastewater, and (4) solid wastes.
Abstract: Over 160 publications related to fermentative hydrogen production from wastewater and solid wastes by mixed cultures are compiled and analyzed. Of the 98 reported cases, 57 used single substrates (mainly carbohydrates), 8 used actual wastewater, and 33 used solid wastes for hydrogen conversion. The key information is compiled in four tables: (1) pretreatment conditions for screening hydrogen-producing bacteria from anaerobic sludge or soil, and the process and performance parameters for (2) single substrates in synthetic wastewaters, (3) actual wastewaters, and (4) solid wastes. Process parameters discussed include pH, temperature, hydraulic retention time, seed sludge, nutrients, inhibitors, reactor design, and the means used for lowering hydrogen partial pressure. Performance parameters discussed include hydrogen yield, maximum volumetric production rate, maximum specific production rate, and conversion efficiency. The outlook for this new technology is discussed at the end.

758 citations

Journal ArticleDOI
TL;DR: Results from batch experiments suggested that Ag-NP transformation to Ag(2)S occured in the nonaerated tank within less than 2 h, which must be considered in future risk assessments.
Abstract: We investigated the behavior of metallic silver nanoparticles (Ag-NP) in a pilot wastewater treatment plant (WWTP) fed with municipal wastewater. The treatment plant consisted of a nonaerated and an aerated tank and a secondary clarifier. The average hydraulic retention time including the secondary clarifier was 1 day and the sludge age was 14 days. Ag-NP were spiked into the nonaerated tank and samples were collected from the aerated tank and from the effluent. Ag concentrations determined by inductively coupled plasma-mass spectrometry (ICP-MS) were in good agreement with predictions based on mass balance considerations. Transmission electron microscopy (TEM) analyses confirmed that nanoscale Ag particles were sorbed to wastewater biosolids, both in the sludge and in the effluent. Freely dispersed nanoscale Ag particles were only observed in the effluent during the initial pulse spike. X-ray absorption spectroscopy (XAS) measurements indicated that most Ag in the sludge and in the effluent was present a...

705 citations

Journal ArticleDOI
TL;DR: In this article, the effect of temperature, hydraulic residence time (HRT), vegetation type and porous media material and grain size on the performance of horizontal subsurface flow (HSF) constructed wetlands treating wastewater, five pilot-scale units of dimensions 3.m in length and 0.75m in width were operated continuously from January 2004 until January 2006 in parallel experiments.

568 citations

Journal ArticleDOI
TL;DR: In this paper, the effect of N2 sparging on hydrogen yield was investigated in non-sterile conditions using a hydrogen-producing mixed culture previously enriched from soya bean meal.

555 citations

Journal ArticleDOI
TL;DR: It seems that the substrate present in the raw influent competitively inhibits the degradation of E1 and E2, and these compounds are therefore removed mainly in activated sludge compartments with low substrate loading.
Abstract: The removal of estrogens (estrone E1, estradiol E2, and ethinylestradiol EE2) was studied in various municipal wastewater treatment processes equipped for nutrient removal. A biological degradation model is formulated, and kinetic parameters are evaluated with batch experiments under various redox conditions. The resulting model calculations are then compared with sampling campaigns performed on different types of full-scale plant: conventional activated-sludge treatment, a membrane bioreactor, and a fixed-bed reactor. The results show a >90% removal of all estrogens in the activated sludge processes. (Due to the analytical quantification limit and low influent concentrations, however, this removal efficiency represents only an observable minimum.) The removal efficiencies of 77% and ≥90% for E1 and E2, respectively, in the fixed-bed reactor represent a good performance in view of the short hydraulic retention time of 35 min. The first-order removal-rate constant in batch experiments observed for E2 vari...

501 citations


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