Environmental Engineering Reference
In-Depth Information
•
recirculation—
The operator must check the rate of recirculation
to ensure that it is within design specifications. Rates above design
specifications indicate hydraulic overloading; rates under design
specifications indicate hydraulic underloading.
Note:
Recirculation is used to reduce organic loading, improve slough-
ing, reduce odors, and reduce or eliminate filter fly or ponding problems.
The amount of recirculation is dependent on the design of the treatment
plant and the operational requirements of the process. Recirculation
flow may be expressed as a specific flow rate (e.g., 2.0 MGD). In most
cases, it is expressed as a ratio (e.g., 3:1, 0.5:1.0). The recirculation is
always listed as the first number, and the influent flow as the second
number. Because the second number in the ratio is always 1, the 1 is
sometimes dropped, and the ratio is written as a single number.
•
media—
The operator should check the uniformity of the media.
7.3.6 Process Control sampling and Testing
To ensure proper operation of the trickling filter, sampling and
scheduling are important; however, for samples and the tests derived
from the samples to be beneficial, operators must perform a variety of
daily or variable tests. Individual tests and sampling may be required
daily, weekly, or monthly, depending on seasonal change. Frequency may
be lower during normal operations and higher during abnormal condi-
tions. The information gathered through the collection and analysis of
samples from various points in the trickling filter process is helpful in
determining the current status of the process as well as identifying and
correcting operational problems. The following routine sampling points
and types of tests will allow the operator to identify normal and abnor-
mal operating conditions.
filter influent tests
•
Dissolved oxygen
• pH
• Temperature
• Settleable solids
• BOD
5
• Suspended solids
•
Metals
recirculated flow tests
•
Dissolved oxygen
•
pH
• Flow rate
•
Temperature
