Abstract
The global population is increasing, and approximately 70% of them will live in cities by the year 2050. Thus, cities are becoming major hotspots for human waste rich with nitrogen (N) and phosphorus (P). Nutrient recycling from human waste reduces the pressure to produce mineral fertilizer, saves natural resources, and reduces environmental pollution. However, nutrient recycling as compost, pellet, raw/treated sludge or incinerated ash is done only on a small scale mainly due to business limitations. Therefore, this review paper aims to identify new sustainable methods for recycling of human waste, with a particular focus on urban areas. The study was conducted by searching for sanitation-related keywords across various databases. Secondary data was collected from the literature and analyzed to produce the result. We found that urban sanitation should be re-designed considering new nutrient recycling technologies, end product markets, and new business models. This approach will facilitate recycling human waste locally and the production of minerals from human waste, thereby assisting in food security and environmental protection, reducing water contamination, and improving public health. Local governments must have a good policy to attract entrepreneurs to develop nutrient recycling into a sustainable business. This article reviews the limitations and constraints of nutrient recycling processes and suggests sustainable solutions.
