Energy balances, GHG emissions and related costs of municipal wastewater sludge treatment chains

Elina Merta, Mona Arnold, Ari Niemelä, Ari Kangas

    Research output: Contribution to conferenceOther conference contributionScientificpeer-review


    The paper presents a case-based comparison of energy balances, green house gas emissions and costs of municipal wastewater sludge process chains based on anaerobic digestion or incineration. Several utilisation options were covered for biogas energy as well for energy from sludge incineration. The potential of enhancing anaerobic digestion by converting the process to thermophilic was studied. In addition, primary precipitation as an operation mode of a WWTP was evaluated as a possible means of enhancing the total energy efficiency. Based on the results, sludge incineration was the most expensive option of the studied scenarios, but justified if the heat generated can be utilised in district heating. Based on costs and energy balances as well as green house gas emissions it is most preferable in anaerobic digestion chains to feed the generated biogas to a gas engine to produce electricity and heat. Moreover, thermophilic anaerobic digestion can improve the overall economy of a WWTP provided that the biogas yield is sufficiently higher than in a mesophilic process.
    Original languageEnglish
    Number of pages15
    Publication statusPublished - 2010
    MoE publication typeNot Eligible
    EventIWA Water and Energy Conference 2010 - Amsterdam, Netherlands
    Duration: 10 Nov 201012 Nov 2010


    ConferenceIWA Water and Energy Conference 2010


    • anaerobic digestion
    • biogas
    • sludge treatment
    • sludge incineration


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