Consistent acidogenic co-fermentation of waste activated sludge and food waste under thermophilic conditions.

Acidogenic co-fermentation of waste activated sludge (WAS) and food waste (FW) under thermophilic conditions enhances process consistency, while overcoming the problem of acetic acid consumption due to growing methanogens. Two long-term continuous co-fermentation experiments were carried out with a WAS:FW mixture (70:30 % in VS) at organic loading rate of 8 gVS/(L·d). Experiment 1 assessed the impact of temperature (35 °C and 55 °C) and WAS origin (WAS_A and WAS_B) in two collection periods.

Microbial core communities in activated sludge plants are strongly affected by immigration and geography.

Background: The microbiota in wastewater treatment plants (WWTPs) and incoming wastewater is critical for the treatment process, the preservation of natural ecosystems and human health, and for the recovery of resources and achievement of sustainability goals. Both core species and conditionally rare and abundant taxa (CRAT) are considered process-critical but little is known about identity as well as true functional and ecological importance. Here, we present a comprehensive investigation of the microbiota of 84 municipal activated sludge (AS) plants with nutrient removal treating ~ 70% of all wastewater within a confined geographical area, Denmark (43,000 km).

Resilience towards organic load and activated sludge variations in co-fermentation for carboxylic acid production.

Two perturbations were investigated in acidogenic co-fermentation of waste activated sludge (WAS) and food waste in continuous mesophilic fermenters: increasing the organic loading rate (OLR) and changing the WAS. A control reactor maintained an OLR of 11 gVS/(L·d), while a test reactor had a prolonged OLR change to 18 gVS/(L·d). For each OLR, two WAS were studied.

Temperature-driven carboxylic acid production from waste activated sludge and food waste: Co-fermentation performance and microbial dynamics.

This work aims to improve the continuous co-fermentation of waste activated sludge (WAS) and food waste (FW) by investigating the long-term impact of temperature on fermentation performance and the underpinning microbial community. Acidogenic co-fermentation of WAS and FW (70:30 % VS-basis) to produce volatile fatty acids (VFA) was studied in continuous fermenters at different temperatures (25, 35, 45, 55 °C) at an organic loading rate of 11 gVS/(L·d) and a hydraulic retention time of 3.5 days.

Effect of feeding frequency on the anaerobic digestion of berry fruit waste.

On-site anaerobic digesters for small agricultural farms typically have feeding schedules that fluctuate according to farm operations. Shocks in feeding, particularly for putrescible waste can disrupt the stable operation of a digester. The effect of intermittent feeding on the anaerobic digestion of rejected raspberries was investigated in four 3L reactors operated in semicontinuous mode for 350 days at 38 °C with a hydraulic retention time of 25 days and an organic loading rate (OLR) of 1gVS/L/d.