300 QUESTIONS AND ANSWERS
1. What is the primary purpose of onsite wastewater treatment systems?
Answer: To treat and dispose of wastewater generated from residential and
commercial sources where connection to a centralized sewer system is not
available or practical.
2. What are the three main components of wastewater? Answer: Solids
(organic and inorganic matter), dissolved substances (nutrients, salts), and
pathogens (bacteria, viruses, parasites).
3. What is BOD and why is it important? Answer: Biochemical Oxygen
Demand - measures the amount of oxygen required by bacteria to decompose
organic matter. It indicates the strength of wastewater and treatment
requirements.
4. What is the difference between aerobic and anaerobic treatment?
Answer: Aerobic treatment uses oxygen to break down organic matter, while
anaerobic treatment occurs without oxygen. Aerobic is faster and more
complete but requires energy for aeration.
5. What is the typical daily wastewater flow for a single-family residence?
Answer: 150 gallons per bedroom per day, or approximately 300-400 gallons
per day for a typical 3-bedroom home.
6. What are the main stages of wastewater treatment in a conventional
system? Answer: Primary treatment (settling/separation), secondary treatment
(biological processing), and tertiary treatment (advanced
treatment/disinfection).
7. What is the purpose of a septic tank? Answer: To provide primary
treatment by allowing solids to settle, scum to float, and partial anaerobic
decomposition of organic matter.
,8. How often should septic tanks be pumped? Answer: Every 3-5 years for
residential systems, depending on tank size, household size, and usage patterns.
9. What is effluent? Answer: The liquid discharge from a septic tank or
treatment system after primary treatment.
10. What is the difference between blackwater and greywater? Answer:
Blackwater contains toilet waste and has higher pathogen levels. Greywater
comes from sinks, showers, and laundry and has lower contamination levels.
11. What is hydraulic loading rate? Answer: The volume of wastewater
applied to a soil absorption area per unit area per day, typically expressed in
gallons per square foot per day.
12. What factors affect soil percolation rates? Answer: Soil texture, structure,
compaction, moisture content, temperature, and organic matter content.
13. What is the minimum separation distance between a septic system and
a water well? Answer: 100 feet minimum, though greater distances may be
required based on soil conditions and local regulations.
14. What causes septic system failure? Answer: Poor maintenance, hydraulic
overloading, inappropriate materials disposal, structural damage, or inadequate
initial design.
15. What is nitrification? Answer: The biological process where ammonia is
converted to nitrite and then to nitrate by bacteria in the presence of oxygen.
16. What is denitrification? Answer: The process where nitrates are converted
to nitrogen gas under anaerobic conditions, helping remove nitrogen from
wastewater.
17. What is the purpose of distribution boxes? Answer: To evenly distribute
effluent from the septic tank to multiple absorption trenches or beds.
18. What is biomat formation? Answer: A biological layer that forms at the
soil interface in absorption areas, consisting of bacteria, organic matter, and fine
particles.
19. What is the typical retention time in a septic tank? Answer: 24-48 hours
minimum for proper settling and initial treatment.
20. What are indicator organisms? Answer: Microorganisms like E. coli and
fecal coliforms used to indicate the presence of pathogenic contamination.
21. What is groundwater mounding? Answer: The temporary rise in
groundwater levels beneath soil absorption systems due to effluent infiltration.
, 22. What is the purpose of baffle systems in septic tanks? Answer: To
prevent scum and solids from entering the outlet pipe and to improve treatment
efficiency.
23. What is alkalinity in wastewater treatment? Answer: The buffering
capacity of water to neutralize acids, important for maintaining proper pH for
biological treatment.
24. What causes hydrogen sulfide odors in septic systems? Answer:
Anaerobic bacterial decomposition of organic matter containing sulfur
compounds.
25. What is the difference between conventional and advanced treatment
systems? Answer: Conventional systems provide primary and basic secondary
treatment. Advanced systems include additional treatment processes for higher
effluent quality.
26. What is total suspended solids (TSS)? Answer: The amount of solid
particles suspended in wastewater, measured by filtration and weighing.
27. What factors influence pathogen survival in soil? Answer: Temperature,
moisture, pH, soil type, organic matter, and sunlight exposure.
28. What is the purpose of ventilation in septic systems? Answer: To allow
gases to escape, prevent vacuum conditions, and promote aerobic conditions in
the tank.
29. What is hydraulic conductivity? Answer: The ability of soil to transmit
water, measured as the rate of water movement through soil under specific
conditions.
30. What are the main nutrients of concern in wastewater? Answer:
Nitrogen and phosphorus, which can cause eutrophication in water bodies if not
properly treated.
31. What is the difference between saturated and unsaturated soil
conditions? Answer: Saturated soil has all pore spaces filled with water.
Unsaturated soil has air-filled pores allowing for better treatment and oxygen
transfer.
32. What is clogging in soil absorption systems? Answer: The reduction in
soil infiltration capacity due to physical, biological, or chemical blockages.
33. What is the purpose of aggregate in absorption trenches? Answer: To
provide storage space for effluent, distribute flow evenly, and prevent soil
compaction.
1. What is the primary purpose of onsite wastewater treatment systems?
Answer: To treat and dispose of wastewater generated from residential and
commercial sources where connection to a centralized sewer system is not
available or practical.
2. What are the three main components of wastewater? Answer: Solids
(organic and inorganic matter), dissolved substances (nutrients, salts), and
pathogens (bacteria, viruses, parasites).
3. What is BOD and why is it important? Answer: Biochemical Oxygen
Demand - measures the amount of oxygen required by bacteria to decompose
organic matter. It indicates the strength of wastewater and treatment
requirements.
4. What is the difference between aerobic and anaerobic treatment?
Answer: Aerobic treatment uses oxygen to break down organic matter, while
anaerobic treatment occurs without oxygen. Aerobic is faster and more
complete but requires energy for aeration.
5. What is the typical daily wastewater flow for a single-family residence?
Answer: 150 gallons per bedroom per day, or approximately 300-400 gallons
per day for a typical 3-bedroom home.
6. What are the main stages of wastewater treatment in a conventional
system? Answer: Primary treatment (settling/separation), secondary treatment
(biological processing), and tertiary treatment (advanced
treatment/disinfection).
7. What is the purpose of a septic tank? Answer: To provide primary
treatment by allowing solids to settle, scum to float, and partial anaerobic
decomposition of organic matter.
,8. How often should septic tanks be pumped? Answer: Every 3-5 years for
residential systems, depending on tank size, household size, and usage patterns.
9. What is effluent? Answer: The liquid discharge from a septic tank or
treatment system after primary treatment.
10. What is the difference between blackwater and greywater? Answer:
Blackwater contains toilet waste and has higher pathogen levels. Greywater
comes from sinks, showers, and laundry and has lower contamination levels.
11. What is hydraulic loading rate? Answer: The volume of wastewater
applied to a soil absorption area per unit area per day, typically expressed in
gallons per square foot per day.
12. What factors affect soil percolation rates? Answer: Soil texture, structure,
compaction, moisture content, temperature, and organic matter content.
13. What is the minimum separation distance between a septic system and
a water well? Answer: 100 feet minimum, though greater distances may be
required based on soil conditions and local regulations.
14. What causes septic system failure? Answer: Poor maintenance, hydraulic
overloading, inappropriate materials disposal, structural damage, or inadequate
initial design.
15. What is nitrification? Answer: The biological process where ammonia is
converted to nitrite and then to nitrate by bacteria in the presence of oxygen.
16. What is denitrification? Answer: The process where nitrates are converted
to nitrogen gas under anaerobic conditions, helping remove nitrogen from
wastewater.
17. What is the purpose of distribution boxes? Answer: To evenly distribute
effluent from the septic tank to multiple absorption trenches or beds.
18. What is biomat formation? Answer: A biological layer that forms at the
soil interface in absorption areas, consisting of bacteria, organic matter, and fine
particles.
19. What is the typical retention time in a septic tank? Answer: 24-48 hours
minimum for proper settling and initial treatment.
20. What are indicator organisms? Answer: Microorganisms like E. coli and
fecal coliforms used to indicate the presence of pathogenic contamination.
21. What is groundwater mounding? Answer: The temporary rise in
groundwater levels beneath soil absorption systems due to effluent infiltration.
, 22. What is the purpose of baffle systems in septic tanks? Answer: To
prevent scum and solids from entering the outlet pipe and to improve treatment
efficiency.
23. What is alkalinity in wastewater treatment? Answer: The buffering
capacity of water to neutralize acids, important for maintaining proper pH for
biological treatment.
24. What causes hydrogen sulfide odors in septic systems? Answer:
Anaerobic bacterial decomposition of organic matter containing sulfur
compounds.
25. What is the difference between conventional and advanced treatment
systems? Answer: Conventional systems provide primary and basic secondary
treatment. Advanced systems include additional treatment processes for higher
effluent quality.
26. What is total suspended solids (TSS)? Answer: The amount of solid
particles suspended in wastewater, measured by filtration and weighing.
27. What factors influence pathogen survival in soil? Answer: Temperature,
moisture, pH, soil type, organic matter, and sunlight exposure.
28. What is the purpose of ventilation in septic systems? Answer: To allow
gases to escape, prevent vacuum conditions, and promote aerobic conditions in
the tank.
29. What is hydraulic conductivity? Answer: The ability of soil to transmit
water, measured as the rate of water movement through soil under specific
conditions.
30. What are the main nutrients of concern in wastewater? Answer:
Nitrogen and phosphorus, which can cause eutrophication in water bodies if not
properly treated.
31. What is the difference between saturated and unsaturated soil
conditions? Answer: Saturated soil has all pore spaces filled with water.
Unsaturated soil has air-filled pores allowing for better treatment and oxygen
transfer.
32. What is clogging in soil absorption systems? Answer: The reduction in
soil infiltration capacity due to physical, biological, or chemical blockages.
33. What is the purpose of aggregate in absorption trenches? Answer: To
provide storage space for effluent, distribute flow evenly, and prevent soil
compaction.
