Characterizing the growing microorganisms at species level in 46 anaerobic digesters at Danish wastewater treatment plants: A six-year survey on microbial community structure and key drivers.

Anaerobic digestion (AD) is a key technology at many wastewater treatment plants (WWTPs) for converting primary and surplus activated sludge to methane-rich biogas. However, the limited number of surveys and the lack of comprehensive datasets have hindered a deeper understanding of the characteristics and associations between key variables and the microbial community composition. Here, we present a six-year survey of 46 anaerobic digesters, located at 22 WWTPs in Denmark, which is the first and largest known study of the microbial ecology of AD at WWTPs at a regional scale.

Identification of microorganisms responsible for foam formation in mesophilic anaerobic digesters treating surplus activated sludge.

Foaming is a common operational problem in anaerobic digestion (AD) systems, where hydrophobic filamentous microorganisms are usually considered to be the major cause. However, little is known about the identity of foam-stabilising microorganisms in AD systems, and control measures are lacking. This study identified putative foam forming microorganisms in 13 full-scale mesophilic digesters located at 11 wastewater treatment plants in Denmark, using 16S rRNA gene amplicon sequencing with species-level resolution and fluorescence in situ hybridization (FISH) for visualization.

MiDAS 3: An ecosystem-specific reference database, taxonomy and knowledge platform for activated sludge and anaerobic digesters reveals species-level microbiome composition of activated sludge.

The function of the microbiomes in wastewater treatment systems and anaerobic digesters is dictated by the physiological activity of their members and complex interactions between them. Since functional traits are often conserved at low taxonomic ranks (genus, species, strain), high resolution taxonomic classification is crucial to understand the role of microbes in any ecosystem. Here we present MiDAS 3, a comprehensive 16S rRNA gene reference database based on full-length 16S rRNA gene amplicon sequence variants (FL-ASVs) derived from activated sludge and anaerobic digester systems in Denmark.

Amarolinea and Microthrix Are Mainly Responsible for Filamentous Bulking in Danish Municipal Wastewater Treatment Plants.

Filamentous bulking is a common serious operational problem leading to deteriorated sludge settling that has long been observed in activated sludge biological wastewater treatment systems. A number of bacterial genera found therein possess filamentous morphology, where some have been shown to be implicated in bulking episodes (e.g.

Monitoring foaming potential in anaerobic digesters.

Foaming in anaerobic digestion (AD) systems for biogas generation can give serious operational problems. The cause of such foaming events is often unclear, and it is therefore not an easy task to predict and subsequently apply preventative measures. Methods for the measurement of the foaming potential of digester sludge are often implemented, but no standardized method is available.

Can Chlorella pyrenoidosa be a bioindicator for hazardous solid waste detoxification?

Four kinds of solid waste residue (SWR, S1 to S4) from different stages in a sequential detoxification process were chosen. The biotoxicity of the leachates from S1 to S4 was tested by Chlorella pyrenoidosa. The growth inhibition, the chlorophyll a (chla) and chlorophyll b (chlb) concentrations, and the ultrastructural morphology of cells of C.

Leaching behavior of iron from simulated landfills with different operational modes.

The aim of the present study was to investigate the leaching behavior of iron from simulated landfills with different operation modes, with an emphasis on the variation of iron in different oxidation state, ferrous Fe(II) and ferric Fe(III) percentage and the distribution of iron content in different landfill leachate fractions. The leaching behavior and accumulated amounts of iron leached out by leachate from conventional landfill (CL) and leachate recirculated landfill (RL) exhibited decidedly different trends except for the initial 28 days. In addition, the percentage of iron leached from CL and RL accounted 1.

[Effects of methane stress on oxidation rates and microbial community structures in different landfill cover soils].

As compared with the ordinary landfill cover material, clay soil, the effect of methane stress on oxidation rate and microbial community structure was investigated in waste soil (material from biologically treated municipal solid waste). The results showed that the moisture content of the clay soil was low, due to the low water retaining capacity. As environmental temperature and rainfall changed, the clay soil caked and inhibited methanotrophs growth.

Releasing behavior of copper in recirculated bioreactor landfill.

The purpose of this study was to determine the releasing behavior of copper in municipal solid waste (MSW) in landfill with respect to refuse and leachate as an inseparable system. Two simulated bioreactor landfills, one with leachate recirculation and the other without, were operated in room temperature for 320 days. Copper in refuse showed behaviors of staggered migration and retention, which corresponded with the degradation process of landfill obviously.

Responses of oxidation rate and microbial communities to methane in simulated landfill cover soil microcosms.

CH4 oxidation capacities and microbial community structures developed in response to the presence of CH4 were investigated in two types of landfill cover soil microcosms, waste soil (fine material in stabilized waste) and clay soil. CH4 emission fluxes were lower in the waste soil cover over the course of the experiment. After exposure to CH4 flow for 120 days, the waste soil developed CH4 oxidation capacity from 0.