Collection of wastewater in storage chambers or filter bags designed to drain liquids away so that solids can be aerobically composted.
Treatment Level: Primary
Relative Cost: low – medium
Amount of Maintenance Interaction: high
Beneficial Byproduct: some – lots (compost)
- No unpleasant odors or gases.
- Produces nutrient rich compost for reuse or sale.
- Excellent in combination with aquaculture.
- Weekly interaction needed to add bulking agents.
- May clog if overloaded, unmanaged, or if the wrong bags are used.
- Maintenance person may see excrement when adding the bulking agent.
Operation & Maintenance
- Add bulking agents such as straw, wood chips/sawdust, or dry leaves weekly – monthly depending on loading.
- Switch feeder pipe between 2 chambers/bags based on volume of chamber (typ. 6 – 12 months)
- Unfed chamber/bag is left to compost for 6 – 12 months, then added to secondary practice.
Blackwater vs Graywater?
- Can treat both in combination, but filter bags are best suited to blackwater systems to decrease the risk of washing out solids.
Secondary Treatment Options
- Liquid (effluent): Drain fields (typical), soak pits, peat filters, treatment wetlands, aquaculture
- Solids (compost): Worm composting, windrow, aquaculture
- Need to locate in an area with easy access for maintenance and compost removal.