Septic tanks, baffled facultative ponds and aerated rock filters: a high-efficiency low-cost wastewater treatment system for small communities up to ~500 p.e

A low-cost high-efficiency wastewater treatment system for small communities up to ~500 p.e. is described. The treatment process comprises a septic tank, a secondary facultative waste stabilization pond and an aerated rock filter. For a wastewater flow of 200 litres per p.e. per day and a BOD contribution of 50 g per p.e. per day the expected final effluent quality is ~5 mg BOD, ~5 mg SS and ~4 mg ammonia-N per litre. The overall land area requirement is ~6 m2 per p.e., although in southern Europe it would be less (~5 m2 per p.e.). The cost of such a WWTP in the UK, including the cost of the land, is around GBP 375 (approx. EUR 600) per p.e.