The surge in Nigeria's population has led to heightened demands for food, clean water, and agricultural products, resulting in a significant increase in waste generation. Nigeria ranks among the top countries globally in terms of waste production, particularly from food, water, and agriculture. Unfortunately, the management of these vast quantities of waste is often inadequate, leading to environmental pollution, disease, and heightened CO₂ emissions. While reducing such waste is important, completely stopping waste generation from food, water, and agriculture is impossible. Therefore, it becomes imperative to adopt eco-friendly and cost-effective approaches to handling this waste, including collection, conversion, treatment, recycling, and reuse. Effectively managing waste can mitigate pollution and its adverse impacts on public health. This review delves into the environmental, economic, and health challenges associated with the generation of waste from food, water, and agriculture in Nigeria. It highlights the importance of implementing sustainable practices for waste treatment, conversion, reuse, and application. By harnessing these waste materials effectively, Nigeria stands to reap significant economic benefits while simultaneously safeguarding the environment from pollution.

This study investigates the impact of temperature on the tribological performance of duplex layer CrN/DLC and nano-multilayers DLC-W coatings deposited using hybrid PVD-PECVD techniques on carburized and hardened 16MnCr5 discs cut from internal combustion engines valve tappets. Reciprocating dry sliding experiments were conducted at 25 °C, 150 °C, 200 °C, and 250 °C to analyze the high-temperature tribological behavior of the coatings. The wear mechanisms were characterized using SEM, EDS mapping, Raman spectroscopy, and nanoindentation. The lowest coefficient of friction was obtained for CrN/DLC at 25 °C. The CrN/DLC coefficients of friction (COF) increase with temperatures due to increasing adhesive wear. Similarly, DLC-W exhibited a comparable trend with increasing temperature from 25 °C to 250 °C. Both coatings’ wear resistance decreased with higher temperatures due to the transformation of sp³ C bonds to sp² C bonds, facilitating the plastic deformation of the coatings and afterward of the substrate. The CrN/DLC displayed superior wear resistance to the DLC-W coating across all temperatures. The DLC-W multilayer coating showed poor wear resistance above 150 °C, being completely removed during the testing. Compared to both coatings, the uncoated 16MnCr5 discs exhibited higher coefficients of friction and wear rates at all temperatures. Predominant wear mechanisms observed in the coated discs were adhesive and abrasive. The study revealed a decrease in the coatings’ structural and mechanical properties with rising temperatures. Hard abrasive WC particles were identified as contributing to increased wear rates in the multilayer DLC-W coatings.