Influent
Raw wastewater arrives from the collection system. Influent flow, BOD, TSS, ammonia, pH and temperature set the load on the whole plant. White River design influent is 8.0 MGD average with BOD 220 mg/L, TSS 240 mg/L, TKN 40 mg/L and alkalinity 260 mg/L.
Screening
Bar screens (often 1/4 to 1/2 inch openings for fine screens) remove rags, plastics and debris that would wrap pumps, plug diffusers and foul digesters. Screenings are washed, compacted and landfilled.
Grit removal
Grit (sand, gravel, eggshells, coffee grounds) wears pumps and fills tanks. Vortex, aerated or detritus grit chambers remove particles larger than about 100 to 150 microns. Grit accumulation in aeration basins and digesters reduces usable volume over time.
Flow measurement and sampling
Accurate influent flow and representative composite samples are the foundation of every loading calculation (F/M, BOD and ammonia loading, oxygen demand). Calibrate flumes and meters regularly and check composite samplers.
Why it matters downstream
- Rags plug RAS pumps and wrap mixers.
- Grit reduces aeration and digester volume.
- Septic influent can cause filament growth (Thiothrix, Type 021N).
- Influent pH and conductivity monitoring catch toxic events early.