Beshah Dawit Alemu, Tiruye Girum Ayalneh, Mekonnen Yedilfana Setarge
Center for Environmental Science, College of Natural and Computational Sciences, Addis Ababa University, P. O. Box 1176, Addis Ababa, Ethiopia.
Ethiopia Chemical and Construction Inputs Industry Development Institute, P. O. Box 6945, Addis Ababa, Ethiopia.
Environ Sci Pollut Res Int. 2021 Apr;28(13):16272-16281. doi: 10.1007/s11356-020-11878-7. Epub 2021 Jan 2.
In recent years, an enormous amount of sludge is generated every day from zero liquid discharge treatment plant due to rapid expansion of industrial parks in Ethiopia. About 30,000 tons of partially dried sludge discharged to the environmental without proper waste management from all industrial parks. Thus, posing serious environmental problems. One of the most plausible means to recycle the excess sludge resource is converting it into energy-efficient brick by combining with clay. Bricks were prepared by incorporating textile sludge at different proportions (10-40%) and temperature (600, 900 and 1200 °C). Clay and sludge samples were collected from the Addis Ababa brick factory PLC and Hawassa Industrial Park. Results revealed that 10 and 20% sludge bricks satisfied criteria of class "A" bricks as per Ethiopia standards, with the compressive strength of 30.43 and 29.10 Mpa, respectively, at 1200 °C. About 26 and 50% of energy were saved during firing of 10 and 20% sludge-containing bricks, respectively, compared with pristine clay bricks. Moreover, too low concentrations of selected heavy metals found in the brick leachate, showing the sludge, were effectively stabilized in the burnt clay bricks. Thus, based on the results, we suggest the rapid utilization of huge amount of partially dried sludge resources for low-cost and efficient large-scale brick production. This will mutually benefit both the industrial parks and brick production industries. In addition, this will create thousands of jobs to the local people. Above all, the solid waste will be managed properly at textile industrial parks.
近年来，由于埃塞俄比亚工业园区的迅速扩张，零液体排放处理厂每天产生大量污泥。所有工业园区约有30000吨部分干燥的污泥未经适当的废物管理就排放到环境中。因此，造成了严重的环境问题。回收过剩污泥资源最可行的方法之一是将其与粘土结合转化为节能砖。通过加入不同比例（10%-40%）的纺织污泥并在不同温度（600、900和1200℃）下制备砖块。粘土和污泥样本分别取自亚的斯亚贝巴砖厂PLC和哈瓦萨工业园区。结果表明，按照埃塞俄比亚标准，10%和20%污泥含量的砖块符合“A”级砖标准，在1200℃时抗压强度分别为30.43和29.10兆帕。与原始粘土砖相比，烧制含污泥量为10%和20%的砖块时分别节省了约26%和50%的能源。此外，在砖块渗滤液中检测到的选定重金属浓度极低，表明污泥在烧制的粘土砖中得到了有效稳定。因此，基于这些结果，我们建议迅速利用大量部分干燥的污泥资源进行低成本、高效的大规模砖生产。这将使工业园区和砖生产行业互利共赢。此外，这将为当地居民创造数千个就业机会。最重要的是，纺织工业园区的固体废物将得到妥善管理。
