Sludge age

Sorption. Most organics are sorbed to a very small degree on the biofloc, ie, < 2 percent. Exceptions are the nondegradable pesticide Lindane, other pesticides, and PCBs. Heavy metals will complex with the ceU wall and precipitate within the floe. Metal accumulation will increase with increasing sludge age. 

For a soluble wastewater, the VSS is proportional to the biomass concentration. Process performance may also be related to the sludge age, which is the average length of time the organisms are in the process. 

The performance, therefore, is related to the F/M or sludge age and the degradabiUty, K. As the F/M decreases or the sludge age increases, greater removals are achieved. It should be noted that the sludge age is proportional to the reciprocal of the F/M. The reaction rate coefficient, iC, as related to wastewaters characteristics. 

As the sludge age is increased, more of the sludge is oxidized and the net sludge wasted is decreased. If the wastewater contains influent volatile suspended sohds, such as that in a pulp and paper mill, the soHds not oxidized in the process must be added to the net wasted. 

As in all biological reactions, nitrification is a function of temperature. For municipal wastewaters, a minimum sludge age of 3.5 d is required at 20°C while the minimum sludge age must be increased to 12 d at 10°C in order to achieve nitrification. 

In one chemical plant, the required sludge age was found to be 22 d at 22°C, whereas for a nontoxic municipal wastewater, the required sludge age is 3 d. 

Evaluates the performance of each unit of a wastewater treatment plant based on hydraulic loadings, solid flux loadings, food/microorganism ratios, sludge age, settleability, and related parameters. 

CRT Cell residence time - the amount of time in days that an average "bug" remains in the process. Also termed "sludge age". 

Sludge age A measure of the length of time a particle of suspended solids has been retained in the activated sludge process. 

Kapdan IK, Ozturk R (2005) Effect of parameters on color and COD removal performance of SBR sludge age and initial dyestuff concentration. J Hazard Mater B 123 217-222... 

Sludge age, 9C = Biomass in reactor/net rate of biomass generation. 

Add a calculation of the operating parameters substrate consumption rate to micro-organisms ratio (Load), solids residence time (0m) and sludge age ((),) to the program. Experiment with variations in the values of these parameters under various conditions of flow and feed concentration to test their value as process control parameters. 

To this was added reactor hydraulics and microbial residence time (sludge age) and a given reactor configuration, resulting in the following Figure 2 ... 

For a bioreactor Mean Cell Residence time = SLUDGE AGE = 0c = Solids Mass/Change in solids mass = X/(5X/ 5t) or... 

One measure of activated sludge systems is the mean cell residence time or sludge age. The different types of systems and much of US terminology is involved with Sludge Age. 

Estimate the food-microorganism ratio (F/M) and sludge age (solid retention time) of an activated sludge process designed to reduce the BOD5 of the spent stream generated from a biological production plant from 1500 mg/L to 50 mg/L. The wastewater flow is Q = 15,000 GPD, aeration tank volume = 45 m, MLVSS = 3000 mg/L, and net biomass yield coefficient (Tn) = 0.28 kg/kg. Also compute the performance efficiency of the plant. 

C mean cell residence time or sludge age (days)... 

Typical response times are of the order 15-30 minutes (i), days (ii), and several days (iii). The net microorganism growth rate is a key design parameter and its reciprocal is termed sludge age or mean cell residence time. An adequate control has to take into consideration, that the growth rate is time-varying (5). 

Wastewater entering the aeration tank is not treated by primary settling. The aeration time (about 30 h) is longer than in conventional systems and requires less aeration. The sludge age is greater and can be extended to more than 15 days. 

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