1. “Alternate” wastewater treatment systems refers to
those which require little or no operator input for daily operation. In addition these systems should require minimum energy and chemical input.

2. Rotating Biological Contactors:

4. RBC are often covered in cold climates:

5. General considerations for RBC’s
Simple to operate
Waste contact time 10 x that of trickling filter
Primary & Secondary sedimentation required

6. Design for RBC’s:
0.6 lbs of BOD5 per 1000 ft2 of media per day
Rotational speed = 1.6 rpm
Basin depth enough to cover 40% of media surface
Media should be less than 12 ft dia.
Energy to drive shaft = 2.5 kw/shaft

7. For greywater treatment:

8. Constructed Wetlands:
Designed and built to mimic natural wetlands where organisms and plants use wastewater as an energy source and nutrients.
Wastewater is applied to the constructed wetland after primary treatment (generally) a septic tank. Greywater can be applied directly.

9. Typical layout (domestic household wastewater):

10. Typical constructed wetland:

12. Alternative scheme (substitution of septic tank)

13. Constructed Wetland design parameter is hydraulic retention time
Constructed Wetland design parameter is hydraulic retention time. Typical number for this parameter is 10 days.
Hydraulic retention time = Vol./Flow rate
For 1000 gal/day flow and a depth of wetland = 2 ft this would give a surface area of 688 ft2.
Typical L/W = 2:1

17. Plants grown in wetland are:
Cattails, bulrush, rushes and sages

21. For blackwater treatment: