Biomethanation of Harmful Macroalgal Biomass in Leach-Bed Reactor Coupled to Anaerobic Filter: Effect of Water Regime and Filter Media

Abstract

Ulva is a marine macroalgal genus which causes serious green tides in coastal areas worldwide. This study investigated anaerobic digestion as a way to manage Ulva waste in a leach-bed reactor coupled to an anaerobic filter (LBR-AF). Two LBR-AF systems with different filter media, blast furnace slag grains for R1, and polyvinyl chloride rings for R2, were run at increasing water replacement rates (WRRs). Both achieved efficient volatile solids reduction (68.4–87.1%) and methane yield (148–309 mL/g VS fed) at all WRRs, with the optimal WRR for maximum methane production being 100 mL/d. R1 maintained more stable methanation performance than R2, possibly due to the different surface properties (i.e., biomass retention capacity) of the filter media. Such an effect was also noted in the different behaviors of the LBR and AF between R1 and R2. The molecular analysis results revealed that the development of the microbial community structure in the reactors was primarily determined by the fermentation type, i.e., dry (LBR) or wet (AF).

Treatment of Cattle Manure by Anaerobic Co-Digestion with Food Waste and Pig Manure: Methane Yield and Synergistic Effect

“…PM showed a remarkably higher VFA concentration than FW and CM (over five-fold), with acetate, propionate, and butyrate (9.3, 5.2, and 7.8 g COD/kg, respectively) as the major VFA components ( Table 1 ). A high VFA concentration can disturb the balance between acid-forming and acid-consuming reactions and thus inhibit methanogenesis [ 33 , 34 ]. PM also contained a significantly higher level of toxic free ammonia nitrogen than the other substrates (>3-fold), consistent with the literature [ 35 , 36 ].…”

Temperature Effects on Methanogenesis and Sulfidogenesis during Anaerobic Digestion of Sulfur-Rich Macroalgal Biomass in Sequencing Batch Reactors

“…For SRB quantification, real-time PCR was performed with a primer set specific for the dissimilatory sulfite reductase gene (dsrA), a molecular marker for SRBs, as previously described [21]. The amplification mixtures for bacterial and methanogenic 16S rRNA genes were prepared with THUNDERBIRD Probe qPCR Mix (TOYOBO, Osaka, Japan), and those for dsrA were with THUNDERBIRD SYBR qPCR Mix (TOYOBO), as described previously [22]. PCR amplification with fluorescence monitoring was carried out in a QuantStudio 12K Flex system (Life Technologies, Carlsbad, CA, USA).…”

“…PCR amplification with fluorescence monitoring was carried out in a QuantStudio 12K Flex system (Life Technologies, Carlsbad, CA, USA). The concentration of a target sequence in unknown samples was determined against the corresponding standard curve prepared as described previously [22]. Each sample was analyzed in duplicate.…”

Characterization and genomic analysis of phage vB_ValR_NF, representing a new viral family prevalent in the Ulva prolifera blooms

“…A total of 10 genes were detected to encode proteins related to DNA replication, regulation and nucleotide metabolism, which to some extent explained that the replication system of phage vB_ValR_NF was independent of the host. Interestingly, KilA encoded by ORF 51 is a conserved DNA binding domain, it widely exists in the proteins of large bacteria and eukaryotic DNA viruses (Pritham et al, 2007), considering that the abundance of viruses infected with eukaryotic algae generally increases during the U. prolifera blooms, so we speculate that the ORF encoding kilA was detected in phage vB_ValR_NF, which may indicate that there may be complex horizontal gene transfer between microbe during this period (Guo et al, 2011;Jung et al, 2018;Bhatnagar et al, 2020;Wang J. et al, 2020). Meanwhile, ORF 57, coding DNA adenine methylase (Dam), was detected in the genome of phage vB_ValR_ NF.…”