Selecting the right biological treatment plant begins with calculating the volume of domestic wastewater and assessing the site conditions. For reliable operation, it is important to consider not only the daily capacity but also the peak load, pipeline elevations, the method of discharging treated water, and the installation and ventilation of the sewer system.
1. Calculate the daily volume of wastewater
First, determine the number of people who live in the house on a permanent basis. For a preliminary selection of a domestic wastewater treatment plant, you can assume an average water consumption of 180–200 liters per permanent resident per day. This is a guideline for calculation, not a universal standard: actual water consumption depends on the plumbing fixtures, the residents’ habits, and how the home is used.
Calculation: The daily wastewater volume is equal to the number of permanent residents multiplied by the per-capita water consumption. To convert liters to cubic meters, divide the resulting value by 1,000.
For example, for 4 permanent residents, the design volume would be 720–800 liters per day. The rated daily capacity of the selected station must be at least equal to the design load. Daily capacity and the geometric volume of the housing are different specifications.
| Number of permanent residents | Consumption per resident, liters per day | Daily wastewater flow, L/day |
|---|---|---|
| 4 | 180–200 | 720–800 |
| 6 | 180–200 | 1080–1200 |
| 8 | 180–200 | 1440–1600 |
2. Check the peak load and occupancy pattern
In addition to the average daily flow rate, take into account the simultaneous use of plumbing fixtures, the volume of the bathtub, the washing machine and dishwasher, and regular visits from guests. The maximum volume of a single wastewater discharge (surge discharge) must comply with the permissible value specified for the specific model in its technical specifications.
For a home used seasonally or with long periods of inactivity, the selection and startup procedure must be coordinated with a technical specialist. The model should be selected based on the actual load and the equipment’s specifications; arbitrarily overestimating capacity is no substitute for a proper calculation.
3. Choose an installation location and check for free drainage
The installation site is selected based on the topography, soil conditions, groundwater level, the location of the house, sources of drinking water, and access for maintenance. The required distances are determined by the design and applicable local requirements.
If site conditions permit, domestic wastewater from the house should flow by gravity to the treatment plant, and treated water should flow by gravity away from the plant. To achieve this, the elevations of the sewer outlet from the house, the inlet and outlet pipes of the treatment plant, and the water discharge point are compared in advance.
Pipelines are laid with the design slope, without reverse slopes or sagging. If the required elevation difference cannot be achieved, a technical solution involving forced drainage is required; this solution is selected for the specific section.
4. Determine in advance how the treated water will be discharged
One possible option is a drainage well, also known as a filter well. It is suitable only if the soil has sufficient permeability, the groundwater level is appropriate, and the requirements for the discharge location are met. For clayey, waterlogged, or flood-prone areas, a different solution may be necessary.
The presence of a treatment plant does not mean that treated water can be discharged to any point on the property or into a body of water. The discharge method is determined based on the quality of the treated water, hydrogeological conditions, and local requirements. Rainwater from the roof and surface runoff should not be directed into the domestic biological treatment system.
5. Follow the installation instructions for your specific model
The BioTop Home product sheets include detailed installation diagrams for the respective models. Before beginning any excavation work, open the diagram for the selected station and check the excavation dimensions, foundation preparation, pipeline elevations, and backfill requirements.
For sites with a high water table, the station’s resistance to buoyancy and the anchoring measures specified in the design must be verified separately. The sequence for filling the housing with water, backfilling, connecting the power supply, and commissioning must follow the manufacturer’s instructions.
After installation, check the tightness of the connections, the flow of drainage, the operation of the equipment, and access to maintenance points. A general diagram does not replace the installation manual for the selected model and the conditions of the specific site.
6. Ensure that the sewer riser is ventilated
The in-building sewer system must be equipped with ventilation as specified in the design. The ventilated sewer riser is extended above the roof and terminated in accordance with the requirements for the location of its outlet. This ensures air exchange and pressure equalization within the sewer system.
Proper ventilation helps prevent water seals from failing when water is drained and helps remove sewer gases. Sinks, shower drains, and other plumbing fixtures must have functional water seals that are filled with water. Ventilation alone does not eliminate odors from a dried-out trap, a leaky connection, or a clogged pipe.
Sewer ventilation must not be combined with domestic exhaust ventilation. The design of the riser and ventilation system must be coordinated with the internal sewer system design and the requirements of the wastewater treatment plant manufacturer.
What to Prepare for the BioTop Home Selection Process
Please provide the specialist with the number of permanent residents and guests, the occupancy schedule, a list of the main plumbing fixtures, the location of the sewer outlet from the house, soil conditions, and the intended method for discharging treated water. This information will help select the appropriate treatment plant and finalize the installation plan.
Compare BioTop Home models based on their rated capacity and maximum load. Before installation, open the product sheet for the model you have selected and review its installation diagram.