Each An Alternative Onsite Septic System (AOSS) is designed for the specific conditions of the property; therefore septic system maintenance and costs will be determined by the combination of components used for the AOSS.
In this blog post, we’ll address the types of Treatment Units used, along with operation and maintenance costs.
Types of AOSS Treatment Units and their Maintenance Costs:
- An Aerobic Treatment Unit (ATU): Wastewater enters a compartment where solids settle and are partially digested by microorganisms. A motor pumps air into the chamber and mixes the liquid, facilitating diffusion of air and supporting aerobic bacteria that further degrade the wastewater. The treated effluent exits the ATU for additional treatment and dispersion through a soil absorption field.
Operation and Maintenance Cost: Between $500 and $700 per year, which includes the cost of electricity to run the air pump and regular inspection costs.
- Fixed-Activated Sludge Treatment (FAST): The wastewater cycles between the oxygenated FAST system and the septic tank. This recycling action causes microorganisms to convert ammonia and nitrates into nitrogen gas, an inert and abundant atmospheric gas. Because the FAST unit features recycling of effluent, it is more effective than a single-pass ATU at removing ammonia and nitrates.
Operation and Maintenance Cost: Typical costs are approximately $300 per year, which includes electricity and regular inspection costs.
Recirculating Sand Filter: This is an additional treatment stage beyond the conventional septic system. Effluent from the septic tank is pressurized and sprayed on a volume of sand. Microorganisms break down organic matter and convert ammonia into nitrate as the effluent filters through the sand. When the effluent reaches the under drain, a portion of the water enters the soil absorption field and the rest re-circulates through the septic tank, where the nitrates are converted into nitrogen gas, an inert gas that can be vented to the atmosphere.
Operation and Maintenance Cost: $200 to $300 per year, including electricity. The system must be inspected and occasionally the top layer of sand must be removed for optimal performance.
- Trickling Filter (AKA fixed-film reactors): Microorganisms typically grow on a specially designed synthetic material, such as a plastic polymer, instead of being carried with the liquid, as in a typical septic system.
Operation and Maintenance Cost: Approximately $200 to $300 per year. The unit must be inspected regularly by a professional.
- Sequencing Batch Reactor: Successfully removes of nitrate, phosphorus, and ammonia from effluent. The design principle consists of a series of processes that occur in sequence in a single underground unit. During the treatment cycle no additional influent is allowed to enter the unit.
Operation and Maintenance Cost: Yearly maintenance costs are on average $250 to $400. This includes electricity, inspections, and pumping.
By law, all AOSS have to be inspected on a yearly basis. For more information on septic system maintenance in Northern Virginia, please contact the experts at SES Mid Atlantic LLC. Serving residential and commercial customers in Northern Virginia since 1987, SES Mid Atlantic LLC specializes in designing and maintaining conventional and alternative onsite septic systems (AOSS).