SSI Engineers and Environmental Consultants were appointed by the Municipality of Maseru in Lesotho to design a sludge handling facility. The sludge waste originates from a textile manufacturer in Lesotho and had to be transported at huge costs to a landfill site in South Africa. Project manager for SSI, Siva Chetty, indicated that this practice was unsustainable due to the costs involved in transporting waste over such long distances.

The solution offered by the engineering firm was to firstly undertake a sludge characterisation study and then to propose a design solution most appropriate to the environmental setting in Lesotho. The approach was based on designing a containment facility which protects the environment whilst reducing disposal costs. Previously, the sludge stockpile was applied to the land before it was sent to the landfill site in South Africa. The excess leachate drained into the ground thereby threatening groundwater quality.

Remedial measures included building the facility with impermeable material to reduce contamination of the groundwater, leakage detection via a groundwater monitoring system, and an excess leachate collection system.

The construction and operational phase will be complemented by an environmental management plan to ensure that the facility does not have an impact on the environment and in particular groundwater quality. The leachate will be returned to the textile effluent treatment plant where it will undergo further treatment such as settling and oxidation.

The project is an interesting application of the waste management hierarchy whereby other means of treatment needs to be investigated such as avoidance, reduction, recycling and only then safe disposal.

There is scope in the design to apply solar drying of sludge to reduce the water content. Medium to long term plans see the beneficial use of the sludge in the manufacture of bricks and as a fill material for infrastructure projects.

Chetty concluded that the project solution was not only innovative but also collaborative and developmental as the project goal identified alternate means of handling the sludge; it was collaborative as water and waste engineers and environmental consultants from the company worked with the team of Brilliant Technology JV in Lesotho in the conceptualisation and execution of this project – and developmental as a previously waste product could now be put to beneficial use.