Solar powered STPs You do ...

Solar powered STPs

You do not state the geographical position of the developing countries but if we assume there is both an abundance of sunshine and reasonable space available for a STP, I would suggest the implementation of stabilisation ponds.  These consist of a series of shallow ponds, usually a minimum of four about 1.5 m deep into which untreated sewage is discharged.  Retention period is typically 30+ days but depends on local conditions.  Treatment occurs by a combination of settlement and natural UV but can produce good quality effluents that need a minimal disinfection treatment. They also have the advantage that fish can be farmed in the maturation or final ponds.

The advantages are little or no external power, little maintenance, no reliance on costly spares and a skilled workforce is not required.  In addition they can provide a protein source and with disinfection of the final effluent, a water source for agriculture.  These systems were first developed in the 1960’s and there are many examples in operation today.