Muhammad Usman

Thermochemical washing of oily sludge is a highly effective strategy for resource recovery. However, the lingering petroleum components within washed sludge still pose considerable environmental pollution risks. In this study, high-temperature bioaugmentation technology was used to promote the removal of petroleum components, and the potential of this technology in the deep treatment of washed oily sludge was investigated, specifically petroleum component degradation and microbial community regulation. The results showed that the petroleum degradation performance was greatly enhanced by the introduction of thermophilic bacteria combined with 200 mg/kg of biosurfactant (T2 group). Under these conditions, the petroleum and moisture contents were successfully reduced to 19.6 g/kg and 4%, respectively. In particular, the contents of n-alkanes and polycyclic aromatic hydrocarbons in the T2 group decreased significantly to 1098.5 and 494.3 mg/kg, respectively, relative to the blank group (4428.5 and 850.7 mg/kg). High-throughput sequencing results indicated that exogenous thermophilic bacteria (Ureibacillus and Bacillus) could rapidly emerge as the dominant genera in the system. In addition, microbial association network and functional analyses revealed that high-temperature bioaugmentation shifted microbial interactions from competition to cooperation, as evidenced by increased positive correlation ratios and modularity values, as well as functional diversification from two modules in the blank group to four modules in the biofortified treatments, thereby enhancing synergistic degradation capabilities for hydrocarbons. This study provides a newly developed approach to oily sludge treatment that simultaneously achieves reduction and harmlessness.

Anaerobic digestion (AD) is commonly used in food waste treatment. Prokaryotic microbial communities in AD of food waste have been comprehensively studied. The role of viruses, known to affect microbial dynamics and metabolism, remains largely unexplored. This study employed metagenomic analysis and recovered 967 high-quality viral bins within food waste and digestate derived from 8 full-scale biogas plants. The diversity of viral communities was higher in digestate. In silico predictions linked 20.8% of viruses to microbial host populations, highlighting possible virus predators of key functional microbes. Lineage-specific virus-host ratio varied, indicating that viral infection dynamics might differentially affect microbial responses to the varying process parameters. Evidence for virus-mediated gene transfer was identified, emphasizing the potential role of viruses in controlling the microbiome. AD altered the specific process parameters, potentially promoting a shift in viral lifestyle from lysogenic to lytic. Viruses encoding auxiliary metabolic genes (AMGs) were involved in microbial carbon and nutrient cycling, and most AMGs were transcriptionally expressed in digestate, meaning that viruses with active functional states were likely actively involved in AD. These findings provided a comprehensive profile of viral and bacterial communities and expanded knowledge of the interactions between viruses and hosts in food waste and digestate.