Food waste recycling for compost production and its economic and environmental assessment as circular economy indicators of solid waste management

Organic waste management (OWM) currently follows the linear economy principle in most of the Gulf countries. Most CE studies to date revolve around the reduction, recycling, and reuse of the material in a production and consumption chain. In this study, the whole process chain's economic and environmental monetary values were investigated to convert organic food waste (OFW) into compost, following the CE indicators. The monetary savings from macronutrients (carbon and NPK) enrichment by applying compost to the soil and its replacement value of the mineral fertilizer have never been reported in the CE model. The OFW production of Makkah city is estimated to increase up to 1.60 Mt in 2030 because of domestic population growth and an increasing number of pilgrims traveling to perform religious rituals. This massive quantity of OFW can produce 0.23-0.40 Mt of compost in 2015-2030 and reduce 0.043-0.076 Mt of CH4 emission. The implementation of this technology will generate net revenue of 240-419 MSAR from compost selling along with a potential substitute of 124-216 kt of chemical fertilizers during 2015-2030, following the CE. The environmental savings (waste dumping and carbon crediting related to CH4 reduction) can be 618-1078 MSAR, while fertilizer replacement savings will be 74-129 MSAR in 2015-2030. In general, implementing the composting technology following the CE model has the potential to add a cumulative net revenue of 1626 MSAR to the national economy of the Kingdom of Saudi Arabia in 2030. Implementing the CE model in OFW generates compost, reduces waste management problems by closing the materials recycling loop, generating extra income, and adds net revenue to the national economy. It will also help the decision-makers devise a suitable sustainable waste management policy.