Characterization of Denim Effluent Treatment Plant Sludge and its Influence on Concrete Hardened Properties

Effluent Treatment Plant (ETP) in denim industries produces tonnes of sludge daily. Removal of this sludge stands among the most difficult natural issues in wastewater treatment methodologies. Inappropriate sludge disposal poses a potent threat to flora, fauna, and human health so there is a dire need to explore the uses of ETP sludge without compromising on sustainability and the environment. The usage of ETP sludge as a cement replacement material is proposed to effectively manage a waste product to support sustainability and circularity for urban renewal. ETP sludge acquired from a denim processing plant was ground to powder form after sun-drying, cleaning and oven-drying. Insight into the chemical and microstructural characterization of processed sludge was carried out by using X-ray Fluorescence, X-ray diffraction, Fourier transform infrared and Scanning Electron Microscope techniques. The presence of heavy metals along with silica was found by using XRF and was verified through XRD patterns. Detailed characterization supported sludge addition as a cement in the concrete samples in a proportion of 10%, 20% and 30%; with and without recyclable, environmentally friendly and reinforced PolyPropylene fibers (1%). It was found that workability for sludge concrete mixes with and without fibers increases with higher substitution. Also, the sludge concrete with 10% substitution was found optimal for achieving higher compressive, tensile, and flexural strength whereas the influence of fibers on the sludge substitution ratio was found to be insignificant in the proposed proportion. ETP Sludge without the additional process of firing or inceneration, can be utilized in light to medium loads bearing construction applications such as paver, paver blocks and bricks.