Wastewater Collection and Preliminary Treatment - Wastewater Operators - page 241

Table 5.1 saMPling and TesTing griT reMoval sysTeMs
Process location Test frequency

Grit removal (velocity) Influent Suspended solids (fixed) Variable

Channel Depth of grit Variable

Grit Total solids (fixed) Variable

Effluent Suspended solids (fixed) Variable

Grit removal (aerated) Influent Suspended solids (fixed) Variable

Channel Dissolved oxygen Variable

Grit Total solids (fixed) Variable

Effluent Suspended solids (fixed) Variable

Chemical addition Influent Jar test Variable

Preaeration Influent Dissolved oxygen Variable

Effluent Dissolved oxygen Variable

Equalization Effluent Dissolved oxygen Variable

5.3.5 equalization

The purpose of flow equalization (whether by surge, diurnal, or
complete methods) is to reduce or remove the wide swings in flow rates
normally associated with wastewater treatment plant loading; it mini-
mizes the impact of storm flows. The process can be designed to pre-
vent flows above maximum plant design hydraulic capacity, to reduce
the magnitude of diurnal flow variations, and to eliminate flow varia-
tions. Flow equalization is accomplished using mixing or aeration equip-
ment, pumps, and flow measurement. Normal operation depends on the
purpose and requirements of the flow equalization system. Equalized
flows allow the plant to perform at optimum levels by providing stable
hydraulic and organic loading. The downside to flow equalization is in
the additional costs associated with construction and operation of the
flow equalization facilities.

5.3.5.1 Operational Considerations

During normal operations, the operator must monitor all mechani-
cal systems involved with flow equalization, watch for mechanical prob-
lems, and take appropriate corrective action. The operator also monitors
dissolved oxygen levels, the impact of equalization on influent, and
water levels in equalization basins, in addition to making any necessary
adjustments.

5.3.6 Preliminary Treatment sampling and Testing

During normal operation of grit removal systems (with the exception of
the screening and shredding processes), the plant operator is respon-
sible for sampling and testing as shown in Table 5.1.