Introduction to Onsite The introduction to septic systems program - PDF document

6/7/2012 Introduction Introduction to Onsite The introduction to septic systems program covers: Wastewater Treatment Systems  Function of a septic system – Septic Systems  Evaluation of septic tank operation  Determining if a septic tank should be Ryan Gerlich pumped. Extension Program Specialist  How to live with a septic system Department of Biological & Agricultural Engineering Texas AgriLife Extension Service Onsite Wastewater Treatment System Onsite wastewater treatment systems? - Rural and Exurban wastewater infrastructure -Water Quality Protection - 25 - 40%, Wastewater Infrastructure What is the system called? •OWTS – Onsite Wastewater Treatment System; Nationally •OSSF – On-Site Sewage Facility; Texas •Septic System Malfunctioning Onsite System Permitting Wastewater Treatment Systems in Texas  Texas Commission on Environmental Quality (TCEQ), Chapter 285, 5000 gallons per day or less  Local Authorized Agent – Usually local Health Department  TCEQ Regional Office  TCEQ, Chapter 217, Greater than 5000 gallons per day. 1

6/7/2012 Malfunction Nuisance  sewage, human excreta, or other organic  Malfunctioning OSSF – An on-site waste discharged or exposed in a manner that sewage facility that is causing a nuisance makes it a potential instrument or medium in or is not operating in compliance with the the transmission of disease to or between 285 OSSF regulations. persons  an overflow from a septic tank or similar device, including surface discharge from or groundwater contamination by a component of an on-site sewage facility; or  a blatant discharge from an OSSF. Evolution of wastewater Outdoor plumbing: the pit privy treatment goals  Goal: designated place  No carrier needed to convey waste  From outdoor plumbing to water reuse  Waste applied directly to the soil  We need to review the history to  Public health concerns understand the present addressed  Management: relocate Disposal Indoor plumbing  Goal: limit human contact  Convenience  Keep wastewater below  Water carrier to ground convey waste out of  Disposal options facility  Public health  ‘Collection system’  “Disposing” of pathogens  Public health and  Treatment?  Environment: pathogens groundwater  Management: contamination keep pipe flowing  Management: install, flush and forget 2

6/7/2012 Septic tank and soil treatment area Goal: TREATMENT AND DISPERSAL  Changing goal:  Disposal: effluent goes away versus treatment  Changes in goals means:  Dispersal: TREATMENT is essential to good systems  Address both public health AND environmental concerns  Siting requirements  Management:  Technological advancements  Disposal: often none at all;  Choice of components and systems  Dispersal: System management is critical  System O&M  Management program Well Aerobic soil Groundwater What is an Onsite Wastewater Decentralized Approach Treatment System? Wastewater Source 1. Collection and Storage 2. Pretreatment components 3. Final Treatment and Dispersal components 4. Wastewater source Collection  Facility type  Piping from facility  Domestic with cleanout  Commercial  Blackwater  Industrial  Graywater  User  Owner/family  Employees 3

6/7/2012 Collection options Pretreatment  Holding tanks  Septic tanks  Composting toilets  Aerobic treatment  Incinerating toilets units  Media filters  Constructed wetlands  Disinfection How do we make the Final Treatment and Dispersal Components wastewater system work?  Evaluate the wastewater  Trench and bed source distribution  Evaluate site  Evapotranspiration beds  Wastewater treatment  Low pressure  Wastewater acceptance distribution trench  Choose a final treatment  Drip field and dispersal component  Spray field  Choose the appropriate pretreatment system  Operation and Maintenance Minimum required separation distances Choices of distribution for various soil types 4

6/7/2012 What is a conventional septic system? Conventional Septic Tank What is a Septic Tank? System  Water tight containers  Concrete  Plastic/ Fiberglass LIDS  Gravity separation/ RISERS detention time  Typically 2-3 days INLET TEE  Heavy sinks SCUM  Lighter floats OUTLET TEE W/  Calm conditions CLEAR LAYER EFFLUENT  Screen assisted SLUDGE SCREEN  Anaerobic digestion Gravity Trench Biomat What is a Grease Tank?  Baffles extend lower in the tank to help retain grease and oil  Typically not needed in most residential systems  Necessary for restaurants 5

6/7/2012 Wastewater distribution method Distribution media  Gravity  Pressure dosed  Rock  Sequential trench  Parallel  Chambers  Pressure distribution • Manifolds in the Field  Gravelless pipe • Beds  Synthetic media Gravel-less Pipe Distribution Gravity Distribution Leaching Chambers Low-Pressure Distribution System 6

6/7/2012 Role of vegetative cover in Mound Distribution Field treatment system  A healthy cover crop is essential for the system to function properly. Plants will:  Take up nutrients  Take up water  Stabilize the soil and prevent erosion  Provide food and habitat for beneficial soil organisms Aerobic Treatment Unit System What is an aerobic treatment unit? Aerobic vs. Anaerobic Processes Aerobic Treatment Unit System (???)  Aerobic  Trash Tank  Aerobic bacteria require O 2 to live and grow  Small septic tank  Aerobic treatment processes require O 2 to proceed  1 day retention time  Common condition in soil treatment, media filters, ATUs  Physical separation  Anaerobic  Anaerobic digestion  Anaerobic bacteria grow in absence of free oxygen,O 2  Anaerobic treatment processes do not use oxygen, but consumption of items, breaks oxygen bonds Ex. SO 4 , NO 3  Common condition in septic tanks, processing tanks, and usually any saturated environment 7

6/7/2012 Aerobic tank Aerobic Treatment Unit System  Aerobic Microbes  Air supply  Require Oxygen to live and grow  Compressor / Aerator  Consume waste and bacteria  Diffusers  Configurations  Oxygen transfer to wastewater Suspended growth: Attached growth:  Mixing of food and organisms  Clarifier  Process were the microbes, cell waste and biomass settle out of the water. Water Quality – Spray Field Aerobic Treatment Unit System  High potential for human  Disinfection contact with water  Disinfection, not sterilization  Secondary- Quality Effluent  Chlorinator  Remove 85-98% of solids • NOT SWIMMING POOL TABLETS! and organic matter  UV light  Remove pathogens?  Distribution  Soil for Final Treatment  Pump tank  This is NOT drinking water!!  Spray field No Playing in Sprinklers!! Spray Field  Low angle spray head  < 15 degrees  Clear area around Feeding the System spray head – 10 feet in the direction of spray from the head Conventional and Aerobic  Vegetation growing Systems for water and nutrient removal  Reseed dead vegetation 8

6/7/2012 Fats, oils and grease SEWAGE COMPOSITION Constituent State at room Comments temperature  Water carrying Fats Solid Non-toxic to the system, origin – waste – Hydraulic animals, will separate in water Loading Oils Liquid Non-toxic to the system, origin –  Organic Loading plants, trouble separating in water  BOD TSS Grease Solid Residual material on appliances; solid material on pans/equipment;  Pathogens petroleum products; moisturizers;  Nutrients bath oils; tanning oils; toxic to the  Phosphorus wastewater system Nitrogen Room temperature assumes 74 degrees F  Chemicals A degreaser will move all components through a system In-Home Businesses/Hobbies Prescription Drugs and Antibiotics  Add stronger waste  Examples of Businesses:  Can kill microbes living in system  Home photography  Add chemicals developing lab  Won’t discriminate against  Increase flow organisms living in the  Barber shops system  Day care  Additional treatment  Bakery components may be  Dog grooming necessary  Taxidermy  Artist  Increase maintenance Septic System Additives Kitchen  Not been proven to be  20% of daily flow beneficial to system performance  Not recommended  Dishwasher  Break up particles that are settled at the bottom  Garbage Disposal and make them suspended  Potential solids loading to downstream components 9