The whole system produces treated wastewater suitable for surface irrigation. This high level of treatment is achievable only with primary + secondary treatment.

The system operates off-grid and utilises solar panels and batteries to operate the pumps required to function.

If you only want a simple system (primary treatment, subsurface discharge) then go back to Primary vermidigester.

Treated effluent disposal

Discharge of treated wastewater should never be into or near water bodies. The golden rule is "dispersal is always better than concentration". The advantage of small scale and domestic vermifiltration is that households can irrigate their own land (plants and trees) at low cost. Once the vermifilter removes pathogens and biological oxygen demand (BOD), the nutrient-rich water has value for irrigating and feeding valuable plants.

Important considerations include:

1. Discharge should only be to soil that does not have a high water table. 

2. Secondary treated effluent can be discharged to the soil surface using drippers, whereas primary treated effluent must be discharged to subsurface effluent fields.

Pump-out tank

Where there is sufficient fall to the irrigation field, a bell siphon could provide sufficient water pressure to irrigate drip lines. However this section will focus on solar systems that incorporate water pumps and batteries, to provide a more versatile irrigation options (uphill OR downhill of the treatment plant).

A solar pump-out tank requires a DC pump, a battery, a solar panel and a controller to switch the pump on and off:

1. Solar panel

A nominal 12 volt 50 watt panel is sufficient for smaller domestic pump-out tanks (e.g. 3 users). Use a 100 watt panel for larger domestic systems.

Cost: Approx. US $70 (50 watt panel).

3. Controller

4. Pump

The pump should not draw more than 10 amps (the capacity of the controller relay) and should exceed the head required for the irrigation lines.

Irrigation

Barbed dripper nozzles are fitted into holes drilled in polythene pipe. These provide better water distribution than simply drilling holes in the pipe. Irrigation lines can either be moved to new locations at regular intervals, or multiple irrigation lines are attached to a main line with taps and rotated into and out of service. Number of nozzles is limited by the flow and pressure provided by the pump to those nozzles. 

This system avoids using filters, because these require regular maintenance and are not necessary. However, 3mm barbed nozzles are much less likely to block with solids than 2mm nozzles. As nozzle diameter increases, the maximum number to maintain an even pressure between all the nozzles decreases. An even pressure between nozzles is required for even water distribution in the irrigation field.

For the system described here, treated effluent is pumped through 10-30 barbed irrigation nozzles at a time. Trial and error will be required to determine number of nozzles used, which will depend on head, irrigation line length and irrigation line diameter. 

See the video below for how these components can be put together for a full system.

see The whole system »