Efficacy of waste stabilization ponds and constructed wetlands adopted for treating faecal sludge in Africa: a review

ABSTRACT

The generation of faecal sludge (FS) in capitals and urban settings of African countries outpaces the available storage, emptying, transportation and treatment technologies. The low technology-based treatment systems for handling FS are preferable and widely adopted in the African context due to their less associated investment and operation costs. The waste stabilization ponds and constructed wetlands were principally developed as wastewater treatment systems however they are widely adopted for treating FS in urban settings of Africa. Less information is known about the efficiency of these systems in lowering FS pollutant concentrations to meet the design specifications and the allowable discharge limits. This paper reviewed the technical efficacy of waste stabilization ponds and the constructed wetlands in treating FS by evaluating the actual treatment efficiency data against the design efficiencies and the maximum allowable discharge limits. The review results revealed that these technologies are user-friendly although they fail to lower the solids concentrations to meet the design and maximum allowable discharge limits. This failure imposes extra costs on operation and maintenance due to the fast filling of solids in the systems hence leading to short-circuiting issues. So, studies on the adequate dewatering technologies of FS before entering the systems are needed.

KEYWORDS:

• Faecal sludge (FS)
• waste stabilization ponds
• constructed wetlands

Highlights

• This paper reviewed the efficacy of waste stabilization ponds and constructed wetlands technologies in treating faecal sludge in African countries.

• The technologies are user friendly as they operate naturally without demanding intensive operation costs if well maintained.

• However, they don’t lower the faecal sludge pollutant concentrations to meet the design specifications and the maximum allowable discharge standards.

• Studies on adequate dewatering technologies of faecal sludge prior to entering the systems should be done so that the solids load is significantly reduced.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

This study did not report any data.

Additional information

Funding

This work was supported by the Higher Education for Economic Transformation (HEET) Project at Ardhi university as part of skills development to Mr. Petro Mwamlima who is a PhD candidate at the Nelson Mandela African Institution of Science and Technology (NM-AIST).