4.7 Adequacy in the context of emergency

Intermittent Sand Filters have a shorter start-up time and are suitable for emergency contexts in stabilisation and recovery phases.

ISFs can be constructed with locally available materials. Proper design and construction are essential, but operation and maintenance can be done by unskilled labour.

The filter is required to be well managed (batch feedings) and maintained (annual cleaning of the upper layer, control and cleaning of the pipes and batch systems). Adequate pre-treatment needs to be ensured for SF to work well.

Odour problems could result from open filter configurations because the effluent layer would require 4-6 hours before complete infiltration. Therefore, buffer zones from inhabited areas are advisable.

For colder regions, it needs to be ensured that the sand surface of the filter does not freeze. A possibility is the furrowing and ridging of the filter beds. Other coverages by wooden planks or plastic are also possible.