Successful owts treatment
1 / 45

Successful OWTS Treatment - PowerPoint PPT Presentation

  • Uploaded on

Successful OWTS Treatment. Siting Site Evaluation System Location Design System Sizing System Selection and Design Installation Operation/Maintenance. Failure. A condition that threatens public health by failure to adequately treat sewage or creating potential for direct contact

I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
Download Presentation

PowerPoint Slideshow about ' Successful OWTS Treatment' - robert

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
Successful owts treatment
Successful OWTS Treatment

  • Siting

    • Site Evaluation

    • System Location

  • Design

    • System Sizing

    • System Selection and Design

  • Installation

  • Operation/Maintenance


  • A condition that threatens public health by failure to adequately treat sewage or creating potential for direct contact

  • Examples:

    • Pooling on ground surface

    • Back up into structure

    • Leaking tanks, pump chamber or collection system

    • Impacted water quality (surface or ground)

Factors affecting owts performance
Factors Affecting OWTS Performance

  • Soil system performs multiple tasks in typical OWTS

    • Treat the water to remove contaminants

    • Dispose of treated water

  • Factors that affect these tasks

    Soil Wastewater Characteristics

    Loading Rates Users’ Lifestyle

    O& M Temperature

    Rainfall Surrounding Development


  • Texture

  • Structure

  • Depth

  • Compaction

  • Landscape Position

Soil horizons soil properties according to depth
Soil Horizons: Soil Properties According to Depth

  • Distinct soil horizons or layers; form from weathering processes

  • Layers have distinct chemical compositions; determines:

    • amounts and state of organic matter

    • amounts of nutrient elements

  • Each layer supports varying amounts and types of microbial communities

    • Surface layers of soils (O layers) are organic

    • Dominated by organic matter (e.g. leaves, twigs, etc.) (= O1 layer)

    • Dominated by unrecognizable organic matter in next lower layer

      • some decomposition has occurred (O2 layer)

    • Sub-surface soil layers (A layers): various combinations of organic and mineral materials which experience increasing amounts of leaching (= eluvial layers)

    • Lower layers (B layers): experience leaching and horizontal movement of materials (= illuvial layers)

    • Lowest soil layers (C layer) experience least weathering; in contact with bedrock

Loading rates
Loading Rates

  • Hydraulic overloading is one of leading causes of OWTS failure

  • Design flow typically based on number of people in house (assumption generally 2 per bedroom)

    • 60 gpd/person (common assumption in design)

  • Loading rates determined by type of soil

Loading rates1
Loading Rates

  • Clogging Mat

  • Gravitational potential

  • Matric Potential

Users lifestyle
Users’ Lifestyle

  • Low-flow devices (toilet, faucets, shower heads, etc.)

  • Rainfall collection

  • Use of garbage disposals

  • Excessive use of FOG

  • Laundry habits

  • Time in Residence

Wastewater characteristics
Wastewater Characteristics

  • BOD5 (above 230mg/L will reduce life of system and level of treatment)

  • Biologically active chemicals (bleach, antibiotics, etc.)

  • FOG

  • Other chemicals (Cleaners, solvents, degreasers, etc.)

Operation and maintenance o m
Operation and Maintenance (O&M)

  • Pump Tanks every 3 to 5 years (plan on every 4)

    • Actual time period should depend on active monitoring of system

  • Conduct at least biannual monitoring of tank levels, baffles, and drainfield

    • This is the minimum, more frequent monitoring recommended (required for advanced systems)

    • Pump tank when sludge layer thickness exceeds 25% of working liquid capacity of the tank, or if scum layer is within three inches of bottom of outlet baffle

Temperature and rainfall
Temperature and Rainfall

  • Temperature

    • Affects flow and mixing in septic tank

    • Soil treatment relies on biological activity

    • Cold slows down biological processes

      • 50% loss in activity for 10ºC drop in temp

      • Activity effectively stops at 2 ºC

  • Rainfall

    • Additional hydraulic load on soil

    • Reduction in vertical separation

    • Benefit-dilute nitrates, however also increase transport rate

Alternative waste treatment
Alternative Waste Treatment

  • Stabilization Ponds

  • Wetlands

  • Composting Toilets

  • Separation of Waste Streams

  • Greywater Sytstems

  • Primitive Systems

Stabilization ponds or lagoons
Stabilization Ponds or Lagoons

  • Aerobic and Facultative Ponds:

  • Biologically Rx by complementary activity of algae and bacteria.

  • Used for raw sewage as well as primary‑ or secondary‑Rx’d. effluent.

  • Bacteria and other heterotrophs convert organic matter to carbon dioxide, inorganic nutrients, water and microbial biomass.

  • Algae use CO2 and inorganic nutrients, primarily N and P, in photosynthesis to produce oxygen and algal biomass.

Stabilization ponds or lagoons1
Stabilization Ponds or Lagoons

  • Many different pond designs have been used to treat sewage:

  • facultative ponds: upper, aerobic zone and a lower anaerobic zone.

  • Aerobic heterotrophics and algae proliferate in the upper zone.

  • Biomass from upper zone settles into the anaerobic, bottom zone.

  • Bottom solids digested by anaerobic bacteria.

Constructed wetlands and enteric microbe reductions
Constructed Wetlands and Enteric Microbe Reductions

  • Surface flow (SF) wetlands reduce enteric microbes by ~90%

  • Subsurface flow (SSF) wetlands reduce enteric microbes by ~99%

  • Greater reduction in SSF may be due to greater biological activity in wetland bed media (porous gravel) and longer retention times

  • Multiple wetlands in series incrementally increase microbial reductions, with 90-99% reduction per wetland cell.

Primitive systems





Comfort station


Post office




White house




Bog House


Primitive Systems

Mr turdley says don t be a fecaphobe
Mr. Turdley Says-“Don’t be a fecaphobe”