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.

Phenol removal from oil refinery wastewater using anaerobic stabilization pond modeling and process optimization using response surface methodology (RSM)

Abstract: Oil refinery process releases toxic pollutants into aqueous environment. Phenol and its derivations as the most important pollutants pose severe environmental concern. In this study, the rectangle anaerobic stabilization pond (ASP) consisting of feed tank with workload of 60 Lit (1 × 0.2 × 1) meter of phenol was used. This study evaluated the interactive effect of phenol concentration (200–400 mg/l), temperature (8–24°C) and Hydraulic retention time of (HRT) (2–5 d) on the efficiency of anaerobic stabilization pond for oil refinery wastewater treatment. In this study, experiments were carried out based on central composite design (CCD) and analyzed and modeled by response surface methodology (RSM) aimed at demonstrating the operating variables and also the interactive effect of three independent variables on 7 responses. The maximum removal efficiency of SCOD, TCOD, SBOD and TBOD were 66.26, 68.95, 65.3 and 67.02, respectively, at phenol concentration of 200 mg/L, HRT of 2 d, and temperature of 24°C. Generally, the ratio of N/P varied between 6.69–9.12 and 7.04–12.93, respectively, in influent and effluent of anaerobic stabilization pond. The maximum phenol removal efficiency reached 70.53 and 81.63 at phenol concentration of 200 mg/L, temperature of 24°C with HRT (2 and 5 d), respectively. The phenol removal efficiency was significantly influenced by increasing the temperature compared to decreasing the phenol concentration. The result indicated that the anaerobic stabilization pond was a capable biological treatment process that could achieve the moderate removal of oil refinery wastewater. © 2017 Desalination Publications. All rights reserved.

Mass Cultivation of Anaerobic Ammonium-Oxidizing Sludge Using a Novel Nonwoven Biomass Carrier

Abstract: Biological conversions of nitrogenous compounds closely resembling the chemistry of the anammox reaction were developed and maintained for approximately two years in fixed-bed, continuous-flow unit processes. Using a novel nonwoven matrix for biomass attachment, the anaerobic, autotrophic biofilm cultures were robust enough to survive occasional operational anomalies and to rebound quickly from temporary setbacks. Using a 2.7-l reactor with a hydraulic retention time of 7.5 hours, influent ammonium (NH 4 +) and nitrite (NO 2 -) concentrations of approximately 250 mg N/l, each, were successfully treated with a total nitrogen (T-N) removal efficiency of 60%. T-N and NH 4 + volumetric removal rates of 40 and 20 mg N/l.h, respectively, were maintained for a one-year period of operation, which are in a suitable range for industrial applications. Using the nonwoven material of the 2.7-l reactor as a seed for a larger 14-l reactor, a fast transition to a stable, relatively high T-N mass removal rate of approximately 300 mg/h (NH 4 -N removal, 150 mg/h) was possible. These results suggest that attached-growth processes such as employed here, with a nonwoven matrix, could serve well not only as a means of nitrogen abatement but also for mass cultivation of the slowly growing anaerobic ammonium-oxidizing cultures for use in development of new reactors.