Comparative life cycle assessment of alternative scenarios for municipal solid waste management (case study: Babol, Iran)

Sustainable management of increasing amounts of municipal solid waste (MSW) has become a major environmental concern because improper MSW management leads to substantial negative environmental impacts and health and safety problems. The life cycle assessment (LCA) method has been recognized as an indispensable tool to support systematic and accurate decisions taken on waste management systems. LCA can make a comparison between different scenarios of waste management systems performance from top to bottom to assess the environmental impacts and consumption of resources. This paper aims to determine the environmental aspects of a less impactful MSW management scenario in Babol, Iran through LCA methodology.

In order to achieve this goal, first, the composition study was conducted in Babol. The results were then utilized as a reliable data source to compare the environmental impacts of MSW management scenarios with a life cycle perspective. System boundaries included collection and transportation of MSW and its treatment and disposal by composting, recycling, incineration with energy recovery, and landfilling methods. Data on the process was evaluated with the IWM-2 model by the means of energy consumption and global warming.

 Babol was estimated to generate 91000 tonnes of waste per year. On average, the generation of waste per capita in Babol was about 606 gr/person/day. After being collected throughout the city, the MSW was discharged at stations to transfer to the heavy vehicles and get transported to Anjil-Si complex waste process and disposal. The main component of the waste stream in Babol was food waste (65.3%). The comparative analysis of the six scenarios underscores the fact that the lower potential environmental loads were related to the 4th scenario in all the impact categories. In particular, the lowest energy use was obtained in scenario 4. In this scenario, composting (60%) and recycling (20%) were included in the waste management plan and resulted in a reduction in the amount of waste disposal as well as energy consumption in landfilling. As excess energy was produced in scenario 4 from the composting and recycling stages (by replacing the produced material with raw material consumed in the life cycle, and also by composting and producing other by-products), less amount of energy was consumed in this scenario. In the case of the global warming impact category, the least burden was originating from scenario 4 due to the reduction of greenhouse gas emissions by energy generation as a result of composting and recycling.

According to the results, the 4th scenario (60% composting, 20% recycling, and 20% landfilling) was confirmed as the best waste final disposal alternative. In particular, CO2 emissions decreased by 54% and the energy consumption decreased by 19%, when the alternative scenario, including the recalled features, was compared to the base-case one. The majority of the MSW of Babol consisted of food waste. With a detailed investigation of organic waste, it is possible to benefit from the composting process as an ideal disposal method.