Life cycle cost of different pretreatment scenarios to increase biogas production from municipal solid waste in Tehran

Organic wastes constitute a large part of urban solid wastes, which are the main source of environmental problems in waste management, including leachate. A suitable method for organic waste management is to use anaerobic digesters to produce biogas. However, in many cases, the low efficiency of biogas production prevents the use of this method. In this study, three pretreatment methods were used to improve biogas production in an anaerobic digester. The difference of each pretreatment method in terms of biogas production was investigated in four scenarios. Also, the cost-benefit of each scenario was calculated in a financial model based on life cycle cost analysis. The results showed that the yield of methane production without pretreatment was 229 ml/gVS, which increased to 358 ml/gVS using pretreatment methods. The capital costs of the scenario with the highest biogas production were 76% higher than the scenario without pretreatment. In this situation, the income increased up to 61.6%, but the most important impact on the life cycle cost was due to the operating costs, which increased by 140% and 155% in two scenarios of using ozone as part of the pre-treatment. Considering the low effect of using ozone as pretreatment in increasing biogas production compared to other pretreatment, as well as the negative effect of this method on the cost-benefit of the project, thermal and NaOH pretreatment recommended as the best pretreatment for anaerobic digester.