4.3.1 The food industry
Food production is a priority in Ethiopia and plays a major part in the economy, with factories producing bread, beverages, sugar and several other products. Many of the production processes require large volumes of water and so most of the factories are located near rivers or boreholes.
The volume of clean water required differs between canneries and the products they are preparing, but ensuring cleanliness is obviously essential. For tomato paste, a popular food product in Ethiopia, it takes about 220 litres of water to produce 10 kilograms of tomato paste. Canning factories that produce tomato paste, such as the Merti Processing Factory in Oromia, generate both solid and liquid waste. The quantity of solid tomato waste may be as much as 15-30% of the total quantity of product (Faris et al., 2002). The wastewater from a cannery will contain organic solids, primarily from washing raw materials such as tomatoes, cleaning equipment, spillage and from floor-washing.
Wastewaters are generated at animal yards, slaughterhouses and packing houses. The main sources are animal faeces, urine, blood and water that has been used for washing floors and surfaces. The pollutants in the wastewaters are organic and can decompose rapidly, generating unpleasant odours. If discharged to a water body, they will cause severe environmental pollution. The meat industry utilises thousands of litres of water per day depending on the size of the facility and the number of animals processed.
What will be the effect of the organic waste from meat packaging if it is discharged into a river?
The organic waste will exert an oxygen demand as it is broken down by bacteria. This could deplete the oxygen available for other living organisms in the water such as fish.
Wastewaters from dairies may come from receiving stations (where milk is delivered from individual farms), bottling plants, creameries, ice cream plants, cheese production units and dried milk production plants. The wastewater from spillage, cleaning and washing usually contains milk which has a very high polluting potential. The polluting potential is the potential of the wastewaters to cause pollution, i.e. damage to the condition, health, safety, or welfare of animals, humans, plants or property.
4.3 Industrial wastewaters in Ethiopia
4.3.2 Textile industry