Sludge-Drying Lagoons: a Potential Significant Methane Source in Wastewater Treatment Plants

Yuting Pan, Liu Ye, Ben Van Den Akker, Ramon Pages, Ronald Musenze, Zhiguo Yuan

    Research output: Contribution to journalArticle

    1 Citation (Scopus)

    Abstract

    "Sludge-drying lagoons" are a preferred sludge treatment and drying method in tropical and subtropical areas due to the low construction and operational costs. However, this method may be a potential significant source of methane (CH4) because some of the organic matter would be microbially metabolized under anaerobic conditions in the lagoon. The quantification of CH4 emissions from lagoons is difficult due to the expected temporal and spatial variations over a lagoon maturing cycle of several years. Sporadic ebullition of CH4, which cannot be easily quantified by conventional methods such as floating hoods, is also expected. In this study, a novel method based on mass balances was developed to estimate the CH4 emissions and was applied to a full-scale sludge-drying lagoon over a three year operational cycle. The results revealed that processes in a sludge-drying lagoon would emit 6.5 kg CO2-e per megaliter of treated sewage. This would represent a quarter to two-thirds of the overall greenhouse gas (GHG) emissions from wastewater-treatment plants (WWTPs). This work highlights the fact that sludge-drying lagoons are a significant source of CH4 that adds substantially to the overall GHG footprint of WWTPs despite being recognized as a cheap and energy-efficient means of drying sludge.

    Original languageEnglish
    Pages (from-to)1368-1375
    Number of pages8
    JournalEnvironmental Science and Technology
    Volume50
    Issue number3
    DOIs
    Publication statusPublished - 2016

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