Residualss

recycled

Backwash and other liquid flow are ___ if possible to help manage residuals.

constituents

There can be a lot of ____ of concern contained in residuals. It’s basically everything that water treatment removed from the clean water. Such as:

• Pathogenic bacteria and viruses

• Giardia cysts and Cryptosporidium

• Turbidity/particles

• DBPs

• Total organic carbon

• Manganese and iron

• Arsenic and other toxic stuff

• Radioactive material

• PFAS

• Algae toxins

sludge production

_____ from chemical usage can be estimated based on the raw water turbidity, plant flow rate, and chemical doses

coagulant

Estimating mass of sludge produced can be done using ___ dose, raw water turbidity plus contributions from other chemicals

recover

Typical goal of residual management is to ___ as much usable water as possible

lagoons

For residual/sludge management, small to mid sized plants commonly use storage ____ for initial sludge management

NOT

Lagoons are (usually) lined earthen basins used to dewater and thicken sludges - it is ____ a permanent storage unit

mechanical dewatering

For residual/sludge management, larger plants may use ____ or other approaches

drying

Lagoons store sludge in stages. Initially they are used to thicken and dewater, and then enter the next stage as being used as a ____ bed for the sludge

inconsistent

Lagoon sizing is ____. As long is it considered weather, fill cycle, dry cycle, and area for berms and access it is fine. One approach is equating mass of dry solids to loading rate to find area per lagoon.

belt filters

This mechanical dewater process can thicken sludge. It usually has a conditioning zone, compression zone, shear and compression zone, and sludge discharge zone as sludge goes down the line.

centrifuge

This mechanical dewater process is a continuous countercurrent or concurrent solid bowl. The bowl rotates, and usually one end on the bottom is for centrate discharge and the other end is for sludge cake discharge.

filter press

The plate and frame ____ is a mechanical dewatering process that uses plates to shift/guide sludge, which somehow separates it from some of the water

landfill

After residuals dry they are usually sent to a ____. The type of ___ it goes to depends on the residuals’ toxicity

CWA

Discharging liquid residuals must follow the ____ rules

SDWA

Underground injection of liquid residuals must follow ____ rules

RCRA (Resource conservation and recovery act)

Land disposal of liquid residuals and solids/sludge residuals must follow ____ rules

RCRA (Resource conservation and recovery act)

Reuse of solid/sludge residuals must follow ___ rules

CWA

Wetland or ocean disposal of solid/sludge residuals must follow ___ rules

CWA and RCRA

Incineration of solid/sludge residuals must follow ___ and ___ rules

NPDES (national pollution discharge elimination system)

The US EPA suggests disposal alternatives for water treatment plant liquid wastes containing natural radioactivity. Radioactive wastes should follow ___ rules.

injection

Residuals associated with membranes and ion exchange are problematic in places like Ohio because there are limited options for disposal. ___ is most often used

PFAS (and also cyanotoxins)

Reuse of residual solids is beneficial, but it is becoming more challenging because of the presence of ___

surface water

Disposing residuals/sludge to ___ have the following regulatory concerns:

• Receiving stream limitations

• Radionuclides

• Odors

• Low Dissolved oxygen levels

• sulfide toxicity

• low pH

deep well injection

Disposing residuals/sludge to ___ have the following regulatory concerns:

• Confining layer

• Upconing to drinking water wells

• Injection well integrity

• Corrosivity