I am trying to understand how many days wastewater materials will be subjected to the bacteria in the activated sludge (is it enough time to complete a specific biodegradation mission a brand is claiming).
Any data points from any system types (and from any countries) are helpful - I am trying to build a view across territories.
If you are looking for a rule of thumb, for municipal sewers without heavy industrial contaminants, aeration of 6 to 8 hours, and 2ry clarification of 3 hours.
Detention time in the secondary clarifier needs to be in the range of 2.0 to 3.0 hours . Too short a detention time will cause solids carryover and too long a detention time will increase septicity.
Hi Nick. I agree with others comments that there are very many variables to be considered. However as a general guide for dry weather flow domestic wastewater treatment in a typical 1980's design system includes a reactor retention period at 6-10 hours and a settlement retention period of at least 6 hours. These minimum times will extend depending on effluent treatability and plant configuration and operation. Hope this helps.
It does depend on what is being broken down, how difficult it is to break down by the activated sludge process and what are the consent levels for discharge. It will also depend on the type of system you have for oxygenation i.e. fine-bubble as against coarse air or even oxygen where unless air is used to remove CO2 the pH drops and it becomes sub-optimal for growth. So it is a very open question.
Time for aeration and clarification depends upon organic material, how much quantity? What is BOD/COD in waste water? How much water quantity is treated?Biological treatment uses microorganisms that occur naturally in wastewater to degrade wastewater contaminants. Clarification is in two stages, Primary and secondary clarifier.
The software are also developed for SBR (Sequential batch reactor) the system operated automatically, please find attached herewith waste water treatment article.
Good question. Of direct interest to me is a polyvinyl alcohol polymer sitting in domestic waste water (a by-product of certain household products normal usage). Specifications allow for different dissolving temperatures, so it may still be a solid polymer and not fully dissolved when reaching waste water processing.
Biodegradation specifications require up to 18 days in contact with a bacteria that is common in active sludge but not common in the environment or especially oceanic water - so if it is not retained for long enough in this environment, polymers may survive - undissolved and not biodegradable - into open water.
What I am trying to get my head around is:
Will it be typical for domestic waste water to be subjected to active sludge bacteria for a matter of hours, for a matter of days or for a matter of weeks? What are the typical upper and lower contact times?
I don't know the terminology well enough to tell you if that is about solid retention or hydraulic retention...do you need extra data?