Hydraulic retention times

HRT Reactor hydraulic retention time TSCA Toxic Substances Control Act... 

S = influent waste concentration (mg/L) = treated waste concentration (mg/L) HRT = reactor hydraulic retention time... 

An anaerobic digester is a no-recycle complete mix reactor. Thus, its performance is independent of organic loading but is controlled by hydraulic retention time (HRT). Based on kinetic theoiy and values of the pseudo constants for methane bac teria, a minimum HRT of 3 to 4 days is required. To provide a safety factor and compensate for load variation as indicated earlier, HRT is kept in the range 10 to 30 days. Thickening of feed sludge is used to reduce the tank volume required... 

This section provides a general overview of the properties of lake systems and presents tlie basic tools needed for modeling of lake water quality. The priiiciptil physical features of a lake are length, depth (i.e., water level), area (both of the water surface and of tire drainage area), and volume. The relationship betw een the flow of a lake or reserv oir and the volume is also an important characteristic. The ratio of the volume to the (volumetric) flow represents tlie hydraulic retention time (i.e., the time it would take to empty out the lake or reservoir if all inputs of water to the lake ceased). This retention time is given by the ratio of the water body volume and tire volumetric flow rate. 

The superficial gas velocity is the air flow rate per unit cross sectional area of the column. The superficial gas velocity is less than 0.4m s 1 and media flow rate is based on liquid velocity. Then, the column may have a hydraulic retention time that is a function of fluid velocity and column diameter. The liquid velocity is given by 4... 

WWTP Population equivalent Flow (m" h- ) Receiving river water Type of wastewater treated Hydraulic retention time Primary treatment Secondary treatment... 

Cosmo balls has been successful in treating sewage effluent with a short hydraulic retention time of only 4h. This study was carried out to evaluate process efficiency using Cosmo balls with a hydraulic retention time of 5 d. 

Because the biological degradation rate of MTBE has been observed to be slower than for other common contaminants, such as BTEX, MTBE will typically be the rate-limiting contaminant that determines the necessary hydraulic retention time for a mixed contaminant system, since it will typically be the slowest to degrade. 

It is important to know from Equation 27.7 that the performance of a complete mix with recycle system does not depend on hydraulic retention time. For a specific wastewater, a biological culture, and a particular set of environmental conditions, all coefficients Ks, b, Y, and km become constant. It is apparent from Equation 27.7 that the system performance is a function of mean cell residence time. 

The mean hydraulic retention time ( / ) can be determined by Equation 27.13, regardless of the types of treatment system used ... 

For example, the mean hydraulic retention time for the entire improved activated sludge system can be expressed as... 

The mechanism for sedimentation (clarification) is based on the density difference between SS and liquid. In addition, SS with larger particle sizes can settle down more easily. Rectangular tanks, circular tanks, combination flocculator-clarifiers, and stacked multilevel clarifiers can be used.14 Oliveira et al.15 reported that flocculation and sedimentation were conducted in the cassava meal industry and reduced the effluent concentration of organics from 14,000 to 2000 mg/L in the bench-scale reactor, with a hydraulic retention time (HRT) of 37 min. 

AF Anaerobic filter, AFBR Anaerobic fluidized bed reactor, UASB Up-flow anaerobic sludge blanket reactor, COD Chemical oxygen demand, HRT Hydraulic retention time. 

Half maximal effective concentration 17a-Ethinyl estradiol Fluidized bed reactor 1 -Hydroxybenzotriazole High performance liquid chromatography Hydraulic retention time... 

Manu B, Chauhari S (2003) Decolorization of indigo and azo dyes in semicontinuous reactors with long hydraulic retention time. Process Biochem 38 1213-1221... 

Since long retention times are often applied in the anaerobic phase of the SBR, it can be concluded that reduction of many azo dyes is a relatively a slow process. Reactor studies indicate that, however, by using redox mediators, which are compounds that accelerate electron transfer from a primary electron donor (co-substrate) to a terminal electron acceptor (azo dye), azo dye reduction can be increased [39,40]. By this way, higher decolorization rates can be achieved in SBRs operated with a low hydraulic retention time [41,42]. Flavin enzyme cofactors, such as flavin adenide dinucleotide, flavin adenide mononucleotide, and riboflavin, as well as several quinone compounds, such as anthraquinone-2,6-disulfonate, anthraquinone-2,6-disulfonate, and lawsone, have been found as redox mediators [43—46]. 

Several studies have reported a positive relationship between the hydraulic retention time of the anaerobic stage and the color removal efficiency [95],... 

The decolorization of Orange II by immobilized P. chrysosporium in a continuous packed-bed reactor (PBR) was investigated [50]. Nearly complete decolorization (95%) with immobilized fungus on PuF was obtained when working at optimal conditions [dye load rate of 0.2 g/l/d, temperature of 37°C, a hydraulic retention time (HRT) of 24 h], and also oxygen gas in a pulsed flow was applied. A correlation between residual MnP activity and decolorization was observed, but no laccase and LiP enzyme activities were detected. 

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