Water and wastewater treatment solutions provider WEC Projects announced in June that it would soon complete the installation of a new WEC Model B packaged sewage treatment plant at the Mothae Diamond Mine, located in the Maluti mountains, 214 km from Maseru,in Lesotho.

The mine is 70% owned by Lucapa Diamonds and 30% by the Lesotho government.

“The mine lacked a sustainable sewage solution,” says WEC Projects sales representative Rudolf de Koning.

Producing 60 m3 of domestic raw sewage a day, Mothae used sewage trucks known as honeysuckers to dispose of the sewage at the nearest disposal facility, almost 130 km away.

“This was obviously a very costly method of sewage disposal,” De Koning stresses.

“WEC proposed the installation of its Model B conventional activated sludge treatment plant with a daily capacity of 80 m3, which allows for future upgrading and expansions of the mine operations.”

The R3.2-million installation is a combined activated sludge and clarification treatment plant. Its modular design simplifies the logistics involved in transporting to the site and simplifies assembly as well as ensures a smaller overall footprint.

The Mothae installation also integrates a Wastemaster that includes screening, de-gritting, and oil removal to cope with fats and oils present in the sewage which could adversely affect the aerobic process in the plant’s reactor.

The Wastemaster removes the oils, fats and nonbiodegradable material upstream from the treatment process.

Additionally, the plant will treat the mine’s grey and black water piped to the current septic system.

“Besides the high fat and oil levels, another factor which could affect the treatment plant’s effectiveness was the high altitude of the site which results in low, fluctuating temperatures,” explains De Koning.

Notably, biological population growth occurs optimally at about 19 °C and above.

He states that, to ensure the proper ambient temperature is maintained, the plant will be assembled within a larger enclosed facility.

In addition to making the mine more environmentally compatible through the effective treatment of its domestic sewage, the plant also reduces the costs of transporting waste to the nearest disposal facility, saving the mine hundreds of thousands each month.

“We worked closely with WEC Projects on site to develop a sustainable solution,” says Mothae Diamond Mine project foreman Thato Tsephe.