Disposal of waste from water treatment plant is one of the major issues most treatment plants seem not to overcome due to the constant generation of this waste as a result of meeting the demand of water and purification of water for human consumption. The effect of disposing sludge constantly in the environment has called for an economical and sustainable way of reusing alum sludge. However, this paper aimed at reviewing the possible literature on applying waste from water treatment plant in various ways, example; in building material; as brick and tiles, in concrete ; as replacement of cement and aggregate, in Geotechnics; as soil stabilizer and in agriculture; as soil fertilizer, in pottery; use as replacement of clay in flower pot production for sustainable disposal. All the above mentioned categories of uses have reviled an effective and efficient way in managing waste from water treatment plant (alum sludge), also a safer and economical manner of disposal. However, the effects when used and the behaviour when it is incorporated with other materials were highlighted, other reuse and disposal options where discussed and the areas not covered (knowledge gap) was identified.

Schmidt rebound hammer test was employed in this study as a nondestructive test. This test method has been universally utilized due to its non-destructiveness for quick and easy assessment of material strength properties and quality of concrete of an existing structure. Industrial waste materials (air-dried alum sludge, treated alum sludge, limestone dust and quarry dust) were employed as replacement material for fine aggregates in this study. A normal strength concrete was designed to achieve 35 MPa at 28 days, with industrial waste materials replacing fine aggregate at different percentages (0%, 5%, 10% and 15%), and then cured for 7, 28 and 180 days. The compressive strength values and rebound numbers for all the mixes obtained were correlated, and a regression equation was established between compressive strength and Schmidt rebound number. The correlation result showed an excellent relationship between rebound number and compressive strength of concrete produced in this study at all curing ages, with correlation coefficients of R² = 0.98, R² = 0.99 and R² = 0.98. The predicted equation showed a strong relationship with the experimental compressive strength. Therefore, it can be used for the prediction of compressive strength of concrete with industrial waste as a replacement for fine aggregate.

This study evaluated the effect of alum sludge as an alternative to fly ash in fabricating geopolymer paste and mortar. The blending of this industrial waste (alum sludge and fly ash) is not only for the benefit of sustainable construction and disposal of industrial waste but also for the reduction of CO₂ emissions due to the increasing production of Portland cement from the cement production industry. A laboratory investigation was carried out on the workability and mechanical properties of geopolymer paste and mortar produced with alum sludge replacement in different proportions (0, 10, 20, 30, 40, 50, 60, 70, 80, 90, and 100). A combination of an alkaline solution of sodium silicate and sodium hydroxide of 14 molarity was employed as an activator for the manufacturing of both paste and mortar geopolymer specimens. It was observed from the findings that geopolymer paste and mortar was flowable and workable when alum sludge is replaced for fly ash at higher replacement content. The addition of alum sludge to the mix improved some properties such as density, strength, water absorption, and the elevated temperature behavior. It was observed that the addition of alum sludge was optimum at the 50% replacement level. The addition of alum sludge up to 50% significantly increased the compressive strength of mortar (up to 80% increase in 28 days strength). The compressive strength of the paste and mortar increased with an increase in curing age. Thus, alum sludge and fly ash can be employed together in the production of eco-friendly cementing material for environmental sustainability.

The presence of the University of Benin (UNIBEN) makes the Ekosodin community economically vital, with local businesses benefiting from the spending of students and staff. Consequently, it is essential to address the problem of soil erosion in the area to facilitate ongoing development and growth. The aim of this study was achieved by collecting four soil samples and analysing various properties such as specific gravity, particle size distribution, Atterberg limits, optimum moisture content, maximum dry density, cohesion, angle of internal friction, and California bearing ratio. The study also examined the impact of adding caustic soda at different concentrations. The resulting unstabilized soil exhibited AASHTO class A-6 and A-7-6 characteristics, featuring a significant proportion of clayey soil with more than 35% passing through sieve No 200, resulting in a fair to poor subgrade rating in pavement design and significant compressibility. Nevertheless, as the percentage of caustic soda increased, there was a reduction in the liquid limit, plastic limit, plasticity index, optimum moisture content, and angle of internal friction. Additionally, higher maximum dry density, cohesion, unsoaked and soaked California Bearing Ratio (CBR) values were recorded with increased caustic soda content. The highest soaked soil CBR value of 26.0% was achieved with a 10% caustic soda stabilization. Therefore, chemical stabilization using caustic soda is recommended for erosion-prone soil in Ekosodin, as it transforms the area's soil from a poor subgrade or foundation to a robust load-bearing material suitable for building and road construction.