For separate sewer systems (blackwater separate from greywater), a septic tank (Imhoff or trichamber type) must be used for toilet wastewater, and a grease trap for kitchen and washing water, according to the diagrams below — unless otherwise specified by the project documentation.

Separate sewer — with Imhoff tank

Site installation — Imhoff tank with grease trap
Site installation — Imhoff tank with grease trap
Schematic — Imhoff tank with grease trap for separate sewer
Schematic: greywater joins blackwater downstream of pre-treatment

Separate sewer — with trichamber tank

Site installation — trichamber tank with grease trap
Site installation — trichamber tank with grease trap
Schematic — trichamber tank with grease trap
Schematic: greywater enters the third chamber of the trichamber tank

Combined sewer

Site installation — Imhoff tank for combined sewer
Site installation — Imhoff tank for combined sewer
Schematic — Imhoff tank for combined sewer, no grease trap
Schematic: for combined sewer use an Imhoff tank only — no grease trap required
⚠️ ALWAYS RESPECT THE CORRECT SIZING PARAMETERS — proper sizing of pre-treatment components is essential for the long-term performance of the constructed wetland. Always refer to the executive project documentation supplied with the system.
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