Kinds of water treatment:
Septic tank disposal systemsWater treatment plants
Innovative systems are being developed to reclaim wastewater waters so that they can be used to irrigate fields, parks or golf courses.
Some developers also say that rather than hiding the wastewater plants, they should come to expect sewage to be reclaimed at small cost producing flowers and shrubs in a park-like setting.
WASTEWATER TREATMENT
22 million systems in operationHalf a million new systems are added per
year30 percent of the people in the US use septic
systems
FACTS ABOUT SEPTIC TANK SEWAGE DISPOSAL SYSTEM
Geologic factors that can affect the suitability of a septic tank disposal system:
Type if soilDepth of the water tableDepth to bedrockTopography
Reasons why most septic tanks fail:Poor soil drainage
Stages of wastewater treatment:Primary treatment
Screening Sedimentation
Secondary treatment Activated sludge Disinfection of the wastewater
Advanced treatment Chemicals Sand filters or carbon filters
WASTEWATER TREATMENT PLANTS
A troublesome aspect of wastewater treatment is the handling and disposal of sludge.
The amount of sludge produced in the treatment process is conservatively estimated as about 54 to 112 grams per person per day, and sludge disposal accounts for 25 to 50 percent of the capital and operating cost of the treatment plant.
Sludge handling and disposal
To convert the organic matter to a relatively stable form
To reduce the volume of sludge by removing liquid
To destroy or control harmful organismsTo produce by-products whose use or sale
reduces cost of processing the sludge
Sludge handling and disposal objectives:
Final disposal of a sludge:
IncinerationBurying it in a landfillUsing it for soil reclamationDumping it in the ocean
The process of recycling liquid waste called the wastewater renovation and conservation cycle
WASTEWATER RENOVATION
WASTEWATER TREATMENT AS RESOURCE RECOVERY
Problems faced by this new technology in being more widely used:
We have a tremendous investment in more traditional wastewater treatment plants and are familiar with them.
There is a general lack of economic incentives to provide for new technologies
There is a general lack of personnel capable of designing, building and operating these systems. However, as more universities are developing true environmental engineering programs, this problem may be rectified