The Solar Thermal Training & Demonstration Initiative

[Lesotho] Solar thermal energy for wastewater treatment

Written/submitted by Ivan Yaholnitsky on 2 July 2019
Heat from solar thermal energy enhances bio-remediation

Earlier this year, Bethel Business and Community Development Centre completed a combined cycle biogas and wastewater treatment system at St. Elizabeth Training Institute in Mohales Hoek, Lesotho.

Water possesses the unusual property of being both a perfect absorber and perfect reflector, depending on the incident angle of radiation. The implication is profound for conventional facultative ponds often used for wastewater treatment in small towns and villages. In winter, morning and evening, little radiation enters the water, temperatures remain cold, and bio-remediation stagnates for several months of the year at these latitudes.

By applying basic solar energy utilization science and technology, waste water treatment can be enhanced and decentralized, while reusing water and recycling nutrients, along with the production of biogas as a useful by-product. Thermal energy is added to the “living machine” through the use of a simple glazed greenhouse structure.

Achieving the SDGs by 2013, calls for unprecedented range, skills and thrust. BBCDC responded to the client’s needs by proposing an engineering solution that was completed within budget and without any external funding. The treated wastewater will be used for landscape irrigation.