Hydraulic retention time (HRT) is the average time a certain amount of wastewater stays in a holding tank before exiting the tank. But then what is the operating time?
The operating time is the total amount of time wastewater is processed in the wastewater treatment reactor. This includes the time it takes to fill the reactor, add chemicals, mix, settle, and discharge the wastewater. It also includes the time required for cleaning and maintenance. The operating time is typically much longer than the hydraulic retention time.
Hydraulic retention time (HRT) and operating time (OT) are both measures of the time that wastewater spends in a treatment reactor, but they are different concepts.
In general, HRT is a design parameter and is used to predict the performance of the reactor, while OT is an operational parameter and is used to evaluate the actual performance of the reactor.
In summary, HRT refers to the amount of time that water spends inside the reactor and is used to design and optimize the reactor, while OT refers to the total time that the reactor has been in operation and is used to evaluate the overall performance of the reactor.
Dear Researchers on wwt systems
:
HRT : Hydraulic Retention Time
HRT is assessed as the total time the influent liquid spends in the process till it becomes an outflank or effluent . This time is given as No. of hours or days.
Let me explain in practical ways.
A process system usually consists of the following when going for natural treatment as follows:
1.. capacity in kl of a pre-process filter, its cubic volume be 5kl
2. Next waste water goes thro 1st stage a primary tank may be like a septic tank its volume say is 30kl
3. After these two, it passes to an anaerobic process with 3 portioned filters- stones course 20-40mm sized - 10kl ) fine say 10mm alsob10kl ) ultra fine - 10kl capacity ie total of 30 kl ) cbm.
4. Tertiary stage say stones less than 5mm for 10kl ) cbm.
Total is 30kl or cbm
5. Last is the finishing cum polishing stage for 5kl) cbm with aeration or fountain spray flow from height to lower level Etc.
When all this is added it becomes 100kl) cbm.. treatment value of the water in full flow.
Now let's have the daily flow as 10kl ) cbm per day.
It means for water to have total 5 stages treatment in 5 tanks it is needed to flow for 100kl.
This means, the water for compelete treatment will takes 100 cbm divided by 10 kl per day - 10 days.. this is HRT in this case.
Next case say flow is 20kl per day, HRT would be 5 days.. for this total process volume of 100kl ) cbm.
As the treatment is done in half time, Remediation will be 50% deficient Etc..
Next will be Operational Time :
Pl assess Next answer given in next article ) paper..
Well wishes for prospects.
Prof Ajit Seshadri
Vels University Chennai India
Operational Time - OT :
Say the wwt plant as described by me earlier is made to operate 24x7 ie no stoppages whatsoever.
Even when a few pumps are to be stopped, troubles set right and progressed and standby pumps used Etc...
Continuously if the plant is on for say 20 days ie x 24 its OT is 480hrs Etc say 500Hrs..
May call for some routine maintenance work Etc
Say in Op for 2mths 60dys, 3 times 500 is 1500Hrs .. then 6mths 180dys 24 - 4320 Hrs.. like 5000hrs 1yr is 10,000hrs.
At all these times regularly maintainance practices are followed.
OT timings govern this need.
Well wishes
Prof Ajit Seshadri
Vels University Chennai India
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