Transcript PowerPoint Presentation - Rural, Onsite & Small Community

Rural, Onsite & Small
Community Wastewater & Waste
Management
Facultative & Anaerobic Lagoons
Lagoon Systems
Objective

Create an ideal environment for
microorganisms to consume waste organic
matter
High strength waste - anaerobic lagoons
Wastewater - Facultative lagoons

AKA Stabilization ponds
Anaerobic Lagoons
Natural continuation of the breakdown of
food in the body
Digestion without oxygen
Acid Formers
Tough
Can produce organic acids over a wide
range of environmental conditions
Organic acids
Lower pH of lagoon
 Smell bad !!!

Methane Formers
Delicate
Easily upset by
Low pH - below 6.7
 High salt concentration (8mmhos/cm)

Anaerobic Digestion
1 Stage Anaerobic Lagoon
2 Stage Anaerobic Lagoon
Startup
Start in Summer
About 1/2 full of clean water
Slowly add waste at first

Design loading after 1 year
Loading
Continuous
Check pH

Add lime if below 6.7
Pump out
Annually
Down to minimum treatment volume
Avoids salt buildup
If salts are over 8 mmhos/cm
 Pump some out and add dilution water

Anaerobic Lagoons
Natural treatment system
No power required
Tend to be large
Dilution
 Long treatment time

Low, but daily management
Stabilization Pond
Sometimes called facultative lagoon
Digestion with oxygen
Used to treat wastewater
Stabilization pond
Shallow basin
Microorganisms at natural concentration
Stabilization Pond
Role of Algae
Design
BOD loading
Hydraulic residence time

3 to 12 months
Loading
Can tolerate fluctuations in loading
Keep inlet below surface to control odors
Management
Maintain banks
Keep weeds from growing in water
 Keep burrowing animals out
 Keep trees from growing

Management
Maintain lnlet & Outlet Structures
Keep sludge from accumulating
 Watch for signs of erosion
 Exercise valves

Discharge
Ideal for irrigation systems
Appropriate level of treatment
 Storage to maximize flexibility for operator

Sludge Management
Debris may wash up on banks

Pretreat with screens
Small amounts of stabilized sludge can be
entrained in irrigation system
Stabilization Ponds
Reduced management
No power requirement
 Low labor time and training
 Limited sludge management

Stabilization Ponds
Large
Treatment takes a long time
 Affected by winter conditions

Relative Size
Fixed
Flim
1x
Lagoon
6x
Reduce the Size?
Stirring
Improves air transfer
 Increases contact between micoorganisms and
waste

Stirred Pond
Impact of Stirring
Pond can be
Smaller
 Deeper
 Shorter residence time

Impact of Stirring
Power required
More operator time & training
More sludge is generated
Readings
Hammer & Hammer 413 - 419
MWPS 18 Section 7.1