What must be done before draining or dewatering any in-ground tank?

Determine the water table level

What is a major limitation of using centrifuges for sludge dewatering?

High energy consumption and associated electrical costs

What is a tank called that excess sludge from a process is pumped into, where the solids are allowed to settle and compact?

Gravity thickener

What is the liquid removed from a settled sludge called?

Supernatant

What is used to precoat vacuum filter belts when dewatering jelly-like alum sludges?

Diatomaceaus earth

What is commonly added to sludge as a conditioner before dewatering?

Polymer

Where may trash and grit removed from the treatment process be disposed of?

An approved sanitary landfill

Dewatered sludge coming off a vacuum filter, belt filter press or centrifuge is called what?

Cake

Calculate the tons of sludge wasted of from a water plant per month using the data given:
Waste sludge flow rate = 10,500 gpd
Waste sludge suspended solids concentration = 8,500 mg/L
Days in month = 30

11 tons per month

What type of sludge dewatering unit consists of a rotating drum covered with a sheer cloth or coil springs that is partially submerged in chemically conditioned sludge slurry?

Vacuum filter

Where is water that is drained from the backwash recovery ponds or lagoons returned to?

The water plant headworks

How do lime softening sludges help the soil when applied to land?

They help raise the pH of the soil

Why are dewatered alum sludges not recommended for disposal on agricultural land?

The aluminum will harden the soils