THE
TREATMENT PROCESS CONTINUE # 2
The
sludge that was separated out in the primary clarifier is pumped
to a digester, where it is also treated by bacterial action. This
sludge must eventually be disposed of by some
method, such as landfilling, incineration, ocean disposal
or application to farmlands as fertilizer. The purpose of treating
the sludge is to:
-
Reduces
the weight and volume of the sludge.
-
Transform
the sludge into a liquid or solid cake form that can be processed,
handled, transported and disposed of easily and economically.
-
Reduces
the odors as much as possible.
-
Kill
all the pathogenic organisms before sludge is returned to
the environment.
As
you can imagine, processing of the sludge is designed to accomplish
these goals at the lowest possible cost. Thus, the sludge treatment
process used in a particular treatment facility will vary
according to how the sludge will be disposed of in the end. for
example, if the sludge will be incinerated in
a high temperature furnace, the main objective of sludge treatment
will be to reduce the water content, so it burns better.
The actual incineration will take care of the other concerns.
Today,
most sludge is disposed of by returning it to the environment.
That is, the treated sludge is applied to form fields as a fertilizer/soil
amendment. When this is done, the sludge must be treated
carefully, so that is does not pose a pollution or other environmental
threat to people, animals, crops, or groundwater.
Digester
system can be designed for either aerobic or anaerobic operation.
In either case, it is very important that the proper types of bacteria
be present to obtain the fastest, most complete digestion. You
can see how important the bacteria are by examining the cause
of the common digester failure.
An
aerobic digester may be functioning well for a long time. Then,
within the space of a few days, the operator will notice drastic
changes occurring. The temperature in the digester drops,
the sludge takes on an unusual appearance, and the normal
bubbling and churning slows - then stops completely. The digester
has gone septic, can
is not functioning at all. No bacteria digestion is going on to
break down the sludge.
This
type of failure can have several causes, such as waste waters
that contain toxic heavy metals, pesticides, or petroleum, but
the most common cause is simply lack of the proper types of bacteria.
The digester stops working because there are not enough good waste-digesting
and displacing the desirable bacteria. The only way to fix this
situation is to kill all bacteria present, then re-seed with Bac-Zyme®
product that contains the right kinds of waste digesting
bacteria. This is done with a very powerful disinfectant chemical
called hydrogen peroxide.
The
process of restarting a digester is laborious, time consuming, expensive,
and involves handling very hazardous chemicals. It may take days
to accomplish, holding up all other operations, and the treatment
plant will not be able to treat the influent waste water. Because
the waste flow cannot be stopped, the treatment plant may be forced
to discharge raw, untreated sewage -- violating permit limits.
State and Federal laws and causing dangerous pollution.
