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Anaerobic digestion has emerged as the preferred treatment for organic fraction of municipal solid waste. Digestate management strategies are devised not only for safe disposal but also to increase the value and marketability. Regulations and standards for digestate management are framed to address the pollution concerns, conserve vulnerable zones, prevent communicable diseases, and to educate on digestate storage and applications. Regulations and the desired end uses are the main drivers for the enhancement of digestate through pretreatment, in vessel cleaning, and post-digestion treatment technologies for solid and liquid fractions of digestate. The current management practice involves utilization of digestate for land application either as fertilizer or soil improver. Prospects are bright for alternative usage such as microalgal cultivation, biofuel and bioethanol production. Presently, the focus of optimization of the anaerobic digestion process is directed only towards enhancing biogas yield, ignoring the quality of digestate produced. A paradigm shift is needed in the approach from ‘biogas optimization’ to ‘integrated biogas–digestate optimization’.

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Inhibitors that reduce viral nucleic acid extraction efficiency and interfere with cDNA synthesis and/or polymerase activity affect the molecular detection of viruses in aquatic environments. To overcome these significant problems, we developed a methodology for assessing nucleic acid yields and DNA amplification efficiencies for environmental water samples. This involved adding particles of adenovirus type 5 and murine norovirus and newly developed primer-sharing controls, which are amplified with the same primer pairs and result in the same amplicon sizes as the targets, to these samples. We found that nucleic acid loss during the extraction process, rather than reverse transcription-PCR (RT-PCR) inhibition, more significantly attributed to underestimation of the presence of viral genomes in the environmental water samples tested in this study. Our success rate for satisfactorily amplifying viral RNAs and DNAs by RT-PCR was higher than that for obtaining adequate nucleic acid preparations. We found that inhibitory properties were greatest when we used larger sample volumes. A magnetic silica bead-based RNA extraction method effectively removed inhibitors that interfere with viral nucleic acid extraction and RT-PCR. To our knowledge, this is the first study to assess the inhibitory properties of environmental water samples by using both control virus particles and primersharing controls.

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