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The promulgation of the Biogas Act in South Korea has increased the number of organic waste treatment facilities and the amount of food waste digestion sludge (FWDS), a byproduct of the biogas process. FWDS recovery involves various challenges, which leads to the accumulation or improper disposal of sludge. Hence, FWDS needs to be treated in environmentally sound and safe ways. In this study, anaerobic digestion sludges were mixed with unused forest biomass to produce fuel. The results showed that pellets produced via mixing of FWDS with unused forest biomass had improved durability, bulk density, and fine particle performance compared to surface-carbonized wood pellets. Carbonized pellets manufactured with 30% FWDS had a moisture content of 11.746% and met all biosolid waste fuel (SRF) standards, except for moisture content. Carbonized pellets prepared with 15% FWDS met the L2 wood pellet standards for ash content (less than 3.0%) and bulk density (greater than 550 kg/m3), as well as all other standard values in both the industrial wood pellet quality standards and bio-SRF criteria. This study confirmed the potential and suitability of digestion sludge and unused forest biomass for fuel utilization by addressing their respective limitations. [ABSTRACT FROM AUTHOR]

This study used biogas from a wastewater treatment plant and bacterial community where methanotrophs, Methylophilus, and ammonia-oxidizing bacteria clusters coexisted to propose an effective method for biological carbon fixation and nitrogen removal in wastewater treatment for carbon capture, utilization, and storage (CCUS). Biogas from wastewater treatment plant was provided, instead of purified CH4, to provide operation and maintenance conditions of bio-catalyst reaction for efficient biological carbon fixation by bacterial community using methane and CO2. This study assessed the conditions to induce type X methanotrophs that can use CO2 as a carbon source, as dominant species in the bacterial community and continuously and effectively supply reducing equivalents required for the conversion of CO2 to methanol within the system. Herein, the results of inducing efficient co-existence of methanotrophs, Methylophilus, and ammonia-oxidizing bacteria cluster in the bacterial community were shown. [ABSTRACT FROM AUTHOR]

This study proposes a novel method to directly treat reject water with a high ammonium content, without relying on dilution. The originality of this method resides in leveraging the coordinated action of a methane- and methanol-dependent bacterial consortium and the biogas generated from wastewater treatment facilities. Specifically, ammonium is removed through autotrophic assimilation in the glutamate cycle of methanotrophs and Methylophilus while, simultaneously, methanol generated by methanotrophs is treated through formaldehyde assimilation as Methylophilus undergo the same ribulose monophosphate cycle as methanotrophs. Using this method, the backflow of high-concentration ammonium into the wastewater treatment process was reduced to 59% in a single operation using a sequencing batch reactor at a mean influent concentration of 877.3 mg L−1. However, the removal rate temporarily declined to an average of 37.6% at a concentration of 800 mg L−1 or above, which was imputed to the influence of toxic intermediates. Image 1 • A novel treatment method for reject water with high-concentration ammonium. • First nitrogen removal method using a CH 4 and CH 3 OH-dependent bacterial consortium. • Simultaneous methanol production and ammonia oxidation by methanotrophs. • Denitrification via RumP and glutamate cycles of methanotrophs and Methylophilus. [ABSTRACT FROM AUTHOR]

We developed a lab-scale aerobic–methane oxidation bioreactor (MOB)–anoxic system, combining a MOB and the aerobic–anoxic denitrification process, and evaluated its potential for advanced nitrogen treatment in wastewater treatment plants (WWTPs). The MOB used biogas generated from a WWTP and secondary-treated wastewater to support mixed methanotroph cultures, which mediated the simultaneous direct denitrification by methanotrophs and methanol production necessary for denitrifying bacteria in the anoxic chamber for denitrification. Compared to the aerobic–anoxic process, the aerobic–MOB–anoxic system with an influent concentration of 4.8 L·day−1 showed a marked increase in the reduction efficiency for total nitrogen (41.9% vs. 85.9%) and PO4−3-P (41.1% vs. 69.5%). However, the integrated actions of high nitrogen and phosphorus consumption are required for methanotroph growth, as well as the production and supply of methanol as a carbon source for denitrification and methane monooxygenase-mediated oxidation of NH3 into N2O by methanotrophs. After three months of continuous operation using actual wastewater, the total nitrogen removal rate was 76.3%, equivalent to the rate observed in a tertiary-advanced WWTP, while the total phosphorus removal rate reached 83.7%. [ABSTRACT FROM AUTHOR]

The development of cost-effective methods, which generate minimal chemical wastewater, for methanol production is an important research goal. In this study, treated wastewater (TWW) was utilized as a culture solution for methanol production by mixed methanotroph species as an alternative to media prepared from commercial or chemical agents, e.g., nitrate mineral salts medium. Furthermore, a realistic alternative for producing methanol in wastewater treatment plants using biogas from anaerobic digestion was proposed. By culturing mixed methanotroph species with nitrate and phosphate-supplemented TWW in municipal wastewater treatment plants, this study demonstrates, for the first time, the application of biogas generated from the sludge digester of municipal wastewater treatment plants. NaCl alone inhibited methanol dehydrogenase and the addition of 40 mM formate as an electron donor increased methanol production to 6.35 mM. These results confirmed that this practical energy production method could enable cost-effective methanol production. As such, methanol produced in wastewater treatment plants can be used as an eco-friendly energy and carbon source for biological denitrification, which can be an alternative to reducing the expenses required for the waste water treatment process. [ABSTRACT FROM AUTHOR]