Lagoon Treatment Systems
The Septic Tank
Wastewater flows into the septic tank where the liquid separates from the solids. The heavier solids settle to the bottom of the tank while the lighter greases float to the top. This material is retained in a tank by vertical baffles. The settling process takes approximately 24 hours. The natural bacteria break down the organic material found in wastewater. Only the treated liquid (effluent) found between the scum and sludge layers flows out of the septic tank and into the lagoon. As the scum and sludge remain in the septic tank, the tank will require pumping to ensure they do not clog the outlet. A properly designed and maintained septic tank will only allow effluent to discharge from the tank to the lagoon.
The effluent, if discharged by gravity, typically flows 6-10 feet out into the lagoon cell. This allows even distribution and more effective treatment. Exposure to sunlight is extremely important to lagoons as it contributes to growth of algae on the water’s surface. Because algae are plants, they live by a process called photosynthesis. This process produces oxygen which many of the bacteria use to break down wastewater. Lagoons in Northern British Columbia are intended to have no discharge of effluent. Trees and aquatic vegetation need to be controlled to allow sunlight exposure and air movement from winds. The surface of the berm should not allow inflow of surface water and spring snow melt to enter into the lagoon cell.
Lagoon Water Quality
Dark sparkling green – good and best condition (good dissolved oxygen and PH)
Dull green to yellow – not so good (poor PH)
Grey to black – very bad (anaerobic or septic conditions, too much sludge)
Tan to brown – usually indicates poor design, erosion, or inflow of surface water (okay if algae is brown)