Bereket Alemu, a 29 years old accountant is a customer and neighbour of Fil Wuha Service Enterprise, the largest hot spa in the city used by thousands of residents.

He uses the hot spa, one of the major wastewater dischargers in the city, at least twice a month and sometimes when he feels the urge.

The hot spa is a major contributor of the nearly 460,000m3 of wastewater discharged in Addis Abeba a day, 80pc of the 575,000m3 of water consumed.

Addis Abeba, as the seat of major regional and international organizations, undergoing rapid socio-economic development and supporting a rising population is facing accelerated demand for potable water both from the domestic and industrial front.

At the same time, the city is dealing with a proportional rise in wastewater discharge that requires treatment before beang released into the natural water bodies.

"I don't know where the wastewater goes," Bereket said, "but it most likely ends up in the nearby rivers or on the streets."

Because of a lack of culture in the proper handling of wastewater and the absence of high volume treatment plants, raw sewage and untreated water drain into open trenches and sometimes even flow on the streets.

In an attempt to address the problem, the city administration constructed the Qality Wastewater Treatment Plant, which was inaugurated in July 2018. The plant was built with 250 million dollars financed by the World Bank.

It has a capacity to treat 100,000 square metres of wastewater a day received from nearly one million residents living in six districts: Kolfe Keranyo, Adiss Ketema, Kolfe, Lideta, Arada and Gulele, in addition to some minor areas in the city.

Addis has three natural drainage areas: Akaki Catchment, Eastern Catchment, Qality Catchment. Their are 12 local primary treatment plants around condominium development areas that by themselves treat 27,500 square metres of waste a day in ‘membrane reactors.’

The new Qality plant is entirely devoted to influent that is received from the Qality Catchment. The plant has been operating since 1973 with a capacity of treating 7,500 square metres of influent a day. The old plant has seen no improvement in the intervening years until the current plan was developed.

The new treatment plant took two years to complete and had undergone six months of testing period. The project was contracted out to AKTOR, a Greek construction company, with a Canadian company, Morrison Hershfield Plc, and local firm ARMA Engineering supervising the project.

The plant falls under Category B treatment system classification, one of three classifications developed by the World Bank.

Category A requires a full environmental assessment; Category B requires a lower level of environmental investigation than the former; and Category C requires no environmental analysis.

The plant falls under Category B, where its potential impact on human population and the environment will be reviewed with a less stringent condition than Category A.

The plant is currently operating with less than 40pc of its capacity, 37,000 square metres of wastewater treatment a day.

There are two main sewer lines feeding the Qality Sewer system, the Western Addis Abeba Sewer Line, which is 28Km long, and the Eastern Addis Abeba Sewer Line, 18Km in length, which is still under construction.

The aim of the treatment plant is to create a stable and healthy environment by reducing wastewater from the environment in the city and to protect public health, according to Zekarias Fanta, sewage collection treatment and re-use core process leader.

According to the World Health Organization (WHO), wastewater treatment includes removing suspended particles, organic material, bacteria, parasitic organisms, allege, viruses and fungi from the influent. The process also involves the removal of medical and pharmacological substances and industrial chemicals.

The Qality Plant, however, does not have the capacity to remove industrial and pharmacological waste and is limited to treating domestic influent from bathroom and kitchen waste, according to Tadeg Mengesha, a process engineer at the plant.

The two main sewer lines convey wastewater to Qality Plant from multiple lateral lines that are connected to households in a network spread across the city.

The collected waste then enters the primary treatment area, where large floating objects such as plastic bottles, sticks and rags are screened out using 75mm and 50mm square screens and the odor is treated.

The secondary treatment is where microorganisms and suspended solid matter are removed from the wastewater in big tanks where nearly 20 cylinders with a capacity to treat 2,000 square metres each help ensure further break down and treatment of the influent.

The final tertiary treatment removes 70pc of impurities from the wastewater. Then the wastewater is disinfected in a mixture of chlorine and sodium hypochlorite before being released as effluent. The solid matter produced in the process then undergo incineration in heat digesters.

The treated effluent from the new plant is directly released into neighbouring vegetable crop farmlands that lie adjacent to the plant and the Aqaqi River. There are no other facilities to recycle or re-use the effluent beyond the treatment. Some crop farmers have benefited from the release of treated water in the past but are now facing new challenges.

Two local brothers, Abiy Amenu and Aregahegn Amenu, are farmers who live in Aqaqi Qality sub-city near the plant.