Sewage Treatment Plant

How about some numbers for the existing plant, like flowrates, influent composition, effluent discharge consent limits, that sort of thing? Is it 1 Population Equivalent or 500000 Population Equivalent?

Almost every treatment system that I've encountered uses both.

The combination means that pathogens that enter the system wil encounter an environment where they will perish and so the quality of treated water (for pathogens) will be high. (aerobic "bugs" will die in the anearobic stage while anaerobic bugs will die on exposure to aerobic conditions.)

A system that is anaerobic only would probably be described as a "digester" and be used to produce methane as an intentional byproduct, maybe for cogeneration. The sludge/liquid output from such systems needs some additional action before release to environment.

Good luck on your quest for information and welcome to CR4.

Hi,

You can contact Thermax Limited,Pune India. Details can be available on iternet.

I just wanted to know in which industries have you seen both process being carried out, I work in semiconductor Industry and we are going only with a Aerobic Digester ( Bio reactor with aeration diffuser). Can you send me the link of such a process or a reference.

Is it possible to tap methane in an industrial plant using a bio-digestor or is a costly affair?

The aerobic system I installed in my last new house produced an effluent that was in a condition of ( Near Drinkable ) and able to be discharged at will however we did install a weeping bed.There is no anaerobic system that I know of that can produce this quality of cleanup of sewage. Most dangerous pathogens are anaerobic and most beneficial bacteria require oxygen for life. That is the way it works in your body for the most part. I never noticed any sewage odor indicating production of methane in the three years I owned the property with the aerobic system.

that is

Anaerobic treatment is used in two places; It is used at the head of a plant to de-nitrify and to remove phosphorus. And it is used for the sludge digestion. Usually there must be a sufficient quantity of solids to go to the digester before it becomes economical to use anaerobic digestion because the capital costs are much higher than for aerobic digestion.

Anaerobic digestion produces methane gases which can be collected and burned to produce energy. Most of that energy is used to heat the digester to maintain its temperature at 95 F. If there is excess beyond that then it can be used to generate electricity.

The normal break even point for an anaerobic system to be cost effective is a normal sewage flow of 2 MGD or greater.

Great information.. thanks

Even the "old" septic tank system used for individual houses has anaerobic process with no addition of stirring, these systems worked as follows.

Aerobic at the inlet where the top surface is exposed to air.

Anaerobic section at the bottom of the tank. It is forced to pass through this section by the baffle across the tank. Flow rates are slow enough that there is no stirring/mixing.

Finally it rises to the overflow point where it is again exposed to atmosphere and becomes aerobic again.

That's the typical 2 chamber domestic "septic" system.

Then we have what are called "Aerated Water Treatment Systems" that typically have seven chambers. The first two are still the usual septic process followed by other stages with air injection, a high surface area section to encourage slime growth to consume any nutrients still in the mix, a sludge return process to return dead slime and other material to the start of the process and eventually an accumulation chamber with chlorine tablet exposure for disinfection.

There are multiple variations on "reed bed" systems, but again, these usually start with the conventional "septic" system followed by the reed beds for nutrient removal.

These are all typically domestic types of systems.

Larger treatment plants have followed many evolutions through the years and range from some that macerate the sewage and dump it in the oceans/rivers, through to those that treat the water to drinking standard for potential re-use. (The "YUCK" factor is currently a social barrier to general implementation of those systems.)