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Research article2019Peer reviewedOpen access

Enhancing anaerobic digestion of dairy and swine wastewater by adding trace elements: evaluation in batch and continuous experiments

Wang, Jing; Westerholm, Maria; Qiao, Wei; Mahdy, Ahmed; Wandera, Simon M.; Yin, Dongmin; Bi, Shaojie; Fan, Run; Dong, Renjie


Trace elements play a critical role for microbial activity in anaerobic digestion (AD) but their effects were probably overestimated in batch tests and should be comparably evaluated in continuous systems. In this study, Fe2+, Co2+, Ni2+, Cu2+ and Zn2+ were added in different concentrations to manure wastewater, and the effects were compared in both batch and continuous systems. The results were used to demonstrate suitable trace element compositions for AD of dairy and swine wastewater, and to compare the outcomes from batch and continuous systems. Fe2+ and Zn2+ were identified as being the most efficient stimulant of dairy and swine wastewater respectively. The addition of 5 mg/L Fe2+ and 0.4 mg/L Zn2+ increased the batch specific methane yield by 62% and 126% for dairy and swine wastewater, respectively. Nevertheless, a lower increment of 2% and 21%, for dairy and swine wastewater was obtained in the 120-day continuously-fed experiments. The 16S rRNA gene sequencing results indicated a relationship between the methanogens population, specific methanogenic activities, propionate, and dissolved hydrogen. Conclusively, the addition of a low dosage of Fe2+ and Zn2+ is a feasible strategy to enhance the methanogenic metabolism of the AD of dairy and swine wastewater respectively.


anaerobic digestion; batch and continuous experiment; dairy and swine wastewater; microbial communities and activities; trace elements

Published in

Water Science and Technology
2019, Volume: 80, number: 9, pages: 1662-1672

    Associated SLU-program

    Food Waste

    Sustainable Development Goals

    SDG6 Clean water and sanitation
    SDG12 Responsible consumption and production

    UKÄ Subject classification

    Water Treatment

    Publication identifier


    Permanent link to this page (URI)