## 1 Introduction  
The increase in the demand for food and sanitation has led to the accumulation of compostable waste, such as yard waste, disposable paper products, and food waste in urban areas. As an eco-friendly solution, such compostable waste can be transformed into compost. The transformation of such compostable waste into compost can rapidly recycle the nutrients and the chemical elements of such waste to be used in agriculture and soil amendment in a shorter time [1; 2; 3; 4]. Despite the rapid accumulation of compostablewaste, modern cities must attain city-wide compostable waste sustainability through a circular economy, such as resource conservation, environmental impact reduction, adherence to responsible production and consumption, business sustainability, and inclusive industrial development. Due to the large volume of compostable waste generated in modern cities and the lack of labor to handle the compostable waste, conventional urban composting facilities lag. Therefore, to handle the incomprehensible amount of compostable waste, automation of the composting process via successful integration of the Internet of Things (IoT) and related technologies with the conventional composting process is a successful strategy [5; 6; 7; 8; 9]. Even though sporadic integration of IoT and other related technologies, such as mobile apps, are adopted for individual composting processes, there is a lack of comprehensive strategic guidance for the digitization of composting in modern cities [1; 10; 11; 12; 13]. Many studies emphasize the benefits of IoT-based composting facilities in a modern city ecosystem. However, proper guidance for an actionable plan and framework for the successful implementation of IoT-based composting in smart cities is hardly found. The rapid increase in the IoT integration into waste management operations worldwide, considerable inefficiency in conventional urban composting plants based on outdated sensors, and lack of novel state-of-the-art IoT components in modern urban composting prompted the development of the review to develop a strategic framework for fully functional IoT-based composting facilities in urban settings. Ref. [14] defines a modern city ecosystem as an urban area leveraging advanced technologies, particularly IoT, to improve the quality of life for its residents, promote sustainable development, and improve urban services. Modern city ecosystems utilize interconnected devices and analytics to optimize energy management, waste management, transportation, and public safety functions. Therefore, this paper focuses on an integral part of the modern city ecosystem, which is urban waste composting. As described by [14], this is one of the vital facets of modern city ecosystems for an efficient, livable, and sustainable environment via IoT integration and active citizen engagement. Governments worldwide are setting mandates such as the Organic Waste Diversion Law of California to encourage the adoption of smart bins and IoT-based real-time waste management monitoring [15; 16]. Modern cities with zero waste goals already use IoT-based composting to track progress and optimize urban waste collection [17; 18]. For example, the U.S. Environmental Protection Agency (EPA) also drives IoT adoption in composting to regulate greenhouse gas emissions in U.S. cities [19]. Even though regulatory and compliance pressure is on the rise in utilizing IoT-based composting solutions, a lack of proper guidance for an actionable plan and framework for the successful implementation of IoT-based composting in smart cities is hardly found. The rapid increase in the IoT integration into waste management operations worldwide, considerable inefficiency in conventional urban composting plants based on outdated sensors, and lack of novel state-of-the-art IoT components in modern urban composting prompted the development of the review to develop a strategic framework for fully functional IoT-based composting facilities in urban settings.