There are 12 tanneries in Modjo town, 73 km southeast of Addis Ababa, and these factories discharge their wastewater into the Modjo river, found on the outskirts of the town. As this river is a tributary to the Awash River, one of the major rivers in Ethiopia, its polluted waters join Awash as well.
The pollution of Modjo river is also extended to the Koka reservoir, the hydroelectric power generating dam constructed in the Awash river basin.
The leather tanning and producing factories in Modjo town have created more than 5000 employment opportunities.
However, as a study done by Abdrie Seid Hassan and Tesfalem Belay Woldeamanuel on Batu and Modjo tanneries entitled Evaluation and Characterization of Tannery Wastewater confirms, the factories don’t have the necessary wastewater treatment systems that meet the legally accepted standard requirements.
Hence, the wastewater from the tanneries is polluting the Modjo river and posing risks to other water bodies this river reaches.
Medhanit, an accountant who lives in Modjo town, has worked in one of the tanneries and says, “Tanneries in and around the town release their wastes to the Modjo river. The river is now toxic, with an unpleasant odor. It is also not suitable for drinking or farming.”
Anyone who comes near the Modjo river can detect the bad smell. Shemeles Bekele (Ph.D.), a chemical engineer, says that when the pollution level of a water body is high it creates an unpleasant odor.
The leather processing industry in Ethiopia has two faces; the risk of pollution and its potential for employment, foreign direct investment, and foreign currency.
The Ethiopian statistics service agricultural sample survey of 2020/2021 indicates that there is an estimated number of 70 million cattle, 42.9 million sheep, and 52.5 million goats in the country.
With this considerable potential to produce leather, Ethiopia earned 33 million USD in the past ten months of the current fiscal year from leather products export. Though the target was to gain 68 million USD, the sector could manage to amass 48% of the plan, according to the Ethiopian Leather Institute report.
Despite the economic advantage of the leather processing sector, its mismanagement continues to harm the environment.
The regulatory body of the Ethiopian Environmental Protection Authority has the mandate to formulate strategies, policies, laws, and standards for industries as well as enforce their implementations. The pollution control standards for tanning and leather production set out by the authority oblige factories to have an amount limit for discharges to water and emissions to air.
However, are these standards being met by the leather-producing factories? The answer is no.
One showcase for this is the project called Modjo Integrated Leather Park, proposed in 2011.
UNIDO (United Nations Industry Development Organization), LIDI (the Ethiopian Leather Industry Development Institute), and AAU (Addis Ababa University) prepared a joint technical team under the Ministry of Industry to propose a project for an environmentally-friendly leather-producing complex in Modjo town.
The Modjo Integrated Leather Park project was expected to be built with all the necessary facilities and create 15,000 up to 25,000 new job opportunities. However, the project hasn’t been implemented until now because of land compensation payment delays for displaced residents.
The Ethiopian constitution guarantees citizens’ right to "a clean and healthy environment" in article 44 of environmental rights. It also asserts in article 92 of environmental objectives that a project’s design and implementation shouldn’t “damage or destroy the environment.”
However, along with the production of leather, the tanning process inevitably produces solid, liquid, and gaseous wastes and sludge which are usually discharged into the environment. To alleviate this problem, the tanneries in Modjo and elsewhere are required to have wastewater treatment and by-products processing plants.
Kassahun Tsegaye, an expert on pollution control in the Ethiopian Environment Protection Authority, said, “In 2019, our authority closed all tanneries in Modjo and forced the firms to build the secondary level treatment plant.”
This measure forced the tanneries to start wastewater treatment facilities. However, Kassahun says the treatments are of a secondary level and their results are not detectable. The secondary level treatment removes organic matters from sewage and disinfects it. This needs proper follow-up control by the responsible body, according to Kassahun.
The impact of the discharges from the different tanneries in Modjo town does not only affect the river and the town with its odor. The wastewater also goes downstream to the Koka reservoir.
Koka reservoir is a dam built in the Awash river basin by Salini Construction in 1960. The reservoir, initially built for hydroelectric power generation, is also used for drinking, irrigation, and fishing by the locals.
“The Koka reservoir is still highly polluted and is going to be dry,” Kassahun, the pollution control expert says.
Woldemariyam Tilaye, the operation head of the Koka hydroelectric power plant, shares Kassahun’s concern. He explained to members of the parliament during their visit to the powerplant in May 2022 that the reservoir faces many problems.
Apart from sedimentation and direct contact with the surrounding community, the wastewater of Modjo tanneries is one factor that is polluting the reservoir, according to Woldemariam.
A water resource expert in Awash Basin Authority, Tassew Zewdu, says, “Controlling the quality of water in the reservoir is not our mandate. But after the administration of the reservoir made official complaints about the wastewater from the tanneries, the Environmental Protection Authority and other stakeholders have made laboratory tests.” Tassew confirms that the results of the laboratory tests proved the pollution level of the reservoir’s water is above average.
The basic chemicals in the leather processing industry are table salt, ammonium salt chloride, sulfide, sulfate, and heavy metals. These chemicals are used to de-hair and preserve leather. The chemicals are detected in the wastewater discharged into the waters of Modjo river and consequently, the Koka reservoir.
Abel Zerfu, an electrical engineer specializing in renewable energy, says that the impact of heavy metals on hydroelectric dams in Ethiopia is not well studied.
“Heavy metals are used in leather industries for the tanning process. These heavy metals are toxic and corrosive by nature,” says Abel, pointing out that the heavy metals damage turbines and other parts of power generation devices in power plants.
Abel also mentions that the wastewater of tanneries contains chemicals like phosphorus and nitrogen. These chemicals make a suitable environment for water hyacinth to flourish. The Koka reservoir's other current problem is the water hyacinth invasion.
Water hyacinth is one factor that causes water amount to decrease in dams, power generating plants blockage, and sedimentation, according to Abel.
The three major principles of the United Nations Industrial Development Organization are: creating shared prosperity, advancing economic competitiveness, and safeguarding the environment. However, the third element is being compromised in Ethiopia as the factories are not taking the necessary measures to keep the environment safe from their waste.