Production of Eco Bricks Using Tannery Sludge as a Partial Substitute for Clay
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Date
2021-10
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Addis Ababa University
Abstract
Tannery sludge is an unavoidable by-product of waste water treatment plants of leather industries and with no safe disposal options; it has the potential to become a significant environmental burden for Ethiopia in the future. Presently, the sludge generated from the leather industries will be land filled without any kind of treatment. Because sludge contains a high concentration of organic and inorganic components, including heavy metals, its accumulation is a burden on the industry and has negative consequences for the environment and human health. As a result, an alternative sludge disposal strategy is required.
The major goal of this research was to see if using TS with certain proportions in the manufacturing of bricks may be a viable alternative to natural clay.
In laboratory-controlled conditions, clay bricks were made with various proportions of sludge (10%, 15%, 20%, and 25% by weight) with firing temperature of 800℃, 900℃ and 1000℃and its potential as a construction material was evaluated based on its Compressive strength, water absorption, weight loss on ignition, bulk density, firing shrinkage, electrical conductivity and heavy metal leaching properties.
As a result, increasing the sludge content in bricks resulted in a decrease in compressive strength and increase in water absorption. When TS content was increased from 0% to 25%, the compressive strength of TS bricks decreased significantly, from 30.24 MPa to 20.15 MPa. Water absorption increased from7.03% to 16.03% when sludge proportion was increased from 0% to 25% at firing temperature of 1000°C.
In addition, total shrinkage and weight loss in burning were compared to raw brick, revealing that total shrinkage did not differ significantly, while weight loss in burning varied from 12.25 % to 30.8 % in raw brick to 25% TS brick at firing temperature of 1000°C.
Furthermore, the sludge altered up to a 15% mixing ratio demonstrates minimal heavy metal leachability as analyzed by TCLP and is compatible with the USEPA standard. As a result of the research, tannery sludge has the potential to be used in the production of sludge bricks with sludge proportion of 10% to 15% and firing temperature of 900°C to1000°C.
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Keywords
Eco Bricks, Clay, Tannery Sludge