Why is sludge sometimes recirculated back into the primary mix area of conventional wastewater plants?

Both a & b

Reduces chemical addition

Helps "seed" the process

None of the above

Question $7$

$1$ pts

When running jar tests, how would you determine the optimal chemical dosages for the lime$-$soda softening process?

By targeting a result of "zero" hardness

By measuring $pH,$ alkalinity, and hardness on the "best jars"

By running a "series" of jar test

Both a & c

Question $8$

$1$ pts

What happens in the resin or media in an ion exchange softener during the softening stage?

Calcium and magnesium ions are exchanged for sodium lons

The $pH$ is decreased

The resin is compressed

The $pH$ is increased

Question $9$

$1$ pts

How would you ensure that large amounts of resin are not being lost during the backwash stage?

Use only warm water for the backwash

Apply the backwash water at a slow steady rate

Keep the time duration of the backwash minimal

Adjust the $pH$ of the backwash water to $7$ before backwashing

Question $10$

$1pts$

How would you determine if an ion exchange softener is removing iron in the ferrous $($soluble$)$ form?

Channeling will occur around the resin

The upper layer of the resin will become plugged

None of the above

The resin will develop an orange or rusty appearance