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Kano River basin, which serves as the main source of water supply to metropolitan Kano, is also used as receiving body for industrial wastes from Sharada and Challawa industrial estates. Of the three major rivers in this basin, the Salanta river was found to receive the highest pollution from the industrial discharges with COD of 8,557.4mg/l, total solids of 16,934.6mg/l, hardness of 1,349.6mg/l CaCO₃, and ammonia nitrogen of 5,150.0mg/l. The Challawa river had COD of 598.7mg/l, total solids of 1,609.9mg/l, hardness of 1,332.0mg/l CaCO₃ and ammonia‐nitrogen 400mg/l. Both empty into the Kano river where the COD was 1,166.9mg/l, total solids 1,458.0mg/l, hardness 2,506.8mg/l and ammonia‐nitrogen 530mg/l. Although these rivers are being used extensively for water supply, irrigation, and fishing, the quality of the water was found to be unsuitable for these purposes. The paper suggests that waste water pre‐treatment by all industries, imposition of direct charges on industrial effluents by the regulating agency, as well as continuous monitoring and surveillance are required to ensure the protection of the water resources in the basin.

The growing quantity of waste is a worrying reality that has resulted in environmental sustainability challenges. Waste paper sludge (WPS) in large quantities from paper mill industry are produced every year. Their disposal in landfills, in general, pollutes the environment. Cement manufacture also contributes to global warming by emitting carbon dioxide. As a result, a novel use of industrial wastes as a supplemental cementitious ingredient in concrete formulation can help to mitigate the environmental problem. This paper aims to study the possibility of usage of WPS as partial replacements of cement for sustainable development of concrete.

This study aims at testing the mechanical properties of concrete that has been mixed with WPS. Between 5% and 20% of the weight of cement, WPS was used to substitute it. The water binder ratios of 0.55, 0.50, 0.45 and 0.42 were all considered for an experiment to better understand the impact of WPS on concrete. In terms of workability, density, water absorption (WA), compressive strength (CS) and flexural strength (FS), concrete mixtures were created, tested and compared to traditional concrete mixes.

According to the findings, the initial and final setting times of the concrete mixtures were both significantly delayed, and the workability and density of the concrete mixtures were both significantly lowered at all water binder ratios and replacement levels. Both compressive and FS of concrete made with WSP declined significantly at all water binder ratio. Substitution of cement by WPS enhanced the WA of all the concrete mixes. The mechanical performance of concrete mixtures that were made with a replacement level of 5% exhibited noticeable improvements. Whereas the more is the replacement levels the more the loss in the mechanical properties were noted. The ideal replacement levels for the WPS are up to 5% only.

This paper contributes to the literature by exploring the ecological and sustainable effects of using WPS in construction materials.