Bayesian uncertainty quantification for anaerobic digestion models.

Uncertainty quantification is critical for ensuring adequate predictive power of computational models used in biology. Focusing on two anaerobic digestion models, this article introduces a novel generalized Bayesian procedure, called VarBUQ, ensuring a correct tradeoff between flexibility and computational cost. A benchmark against three existing methods (Fisher's information, bootstrapping and Beale's criteria) was conducted using synthetic data.

Resource recovery using enriched purple phototrophic bacteria in an outdoor flat plate photobioreactor: Suspended vs. attached growth.

Purple phototrophic bacteria (PPB) can produce single-cell protein from wastewater at high yields. Growing in a biofilm vs suspended can improve product quality and consistency. This study compares suspended and attached growths of enriched PPB cultures in an outdoor flat plate photobioreactor treating poultry-processing wastewater.

Expanding mechanistic models to represent purple phototrophic bacteria enriched cultures growing outdoors.

The economic feasibility of purple phototrophic bacteria (PPB) for resource recovery relies on using enriched-mixed cultures and sunlight. This work presents an extended Photo-Anaerobic Model (ePAnM), considering: (i) the diverse metabolic capabilities of PPB, (ii) microbial clades interacting with PPB, and (iii) varying environmental conditions. Key kinetic and stoichiometric parameters were either determined experimentally (with dedicated tests), calculated, or gathered from literature.

Light attenuation in enriched purple phototrophic bacteria cultures: Implications for modelling and reactor design.

Light attenuation in enriched purple phototrophic bacteria (PPB) cultures has not been studied, and its understanding is critical for proper process modelling and reactor design, especially for scaled systems. This work evaluated the effect of different biomass concentrations, reactor configurations, wastewater matrices, and growth conditions, on the attenuation extent of near infra-red (NIR) and ultraviolet-visible (UV-VIS) light spectra. The results show that increased biomass concentrations lead to higher light attenuation, and that PPB absorb both VIS and NIR wavelengths, with both fractions of the spectrum being equally absorbed at biomass concentrations above 1,000 g COD·m.

Method development for PPB culture screening, pigment analysis with UPLC-UV-HRMS vs. spectrophotometric methods, and spectral decomposition-based analysis.

PPB carotenoids are usually measured through spectrophotometric analysis, measuring total carotenoids (TCs) which has low accuracy and cannot identify individual carotenoids or isomers. Here, we developed an ultra-performance liquid chromatography method with ultraviolet and high-resolution mass spectrometry detection (UPLC-UV-HRMS) to quantify neurosporene, lycopene, and bacteriochlorophyll a contents in PPB cultures. The method exhibited satisfactory recoveries for individual pigments (between 82.

Creating value from purple phototrophic bacteria via single-cell protein production.

Mixed culture purple phototrophic bacteria (PPB) is a rapidly emerging technology for resource recovery from wastewaters. PPB biomass can be used as single-cell protein, with a high protein content complemented by value-added components (e.g.

Outdoor demonstration-scale flat plate photobioreactor for resource recovery with purple phototrophic bacteria.

To make purple phototrophic bacteria (PPB)-based technologies a reality for resource recovery, research must be demonstrated outdoors, using scaled reactors. In this study, a 10 m long PPB-enriched flat plate photobioreactor (FPPBR) with a volume of 0.95 m was operated for 253 days, fed with poultry processing wastewater.

Naturally illuminated photobioreactors for resource recovery from piggery and chicken-processing wastewaters utilising purple phototrophic bacteria.

Resource recovery from wastewater, preferably as high value products, has become an integral part of modern wastewater treatment. This work presents the potential to produce single cell protein (SCP) from pre-settled piggery wastewater (PWW) and meat chicken processing wastewater (CWW), utilising anaerobic purple phototrophic bacteria (PPB). PPB were grown as biofilm in outdoors 60 L, 80 L and 100 L flat-plate reactors, operated in sequential batch mode.

The interaction between lipids and ammoniacal nitrogen mitigates inhibition in mesophilic anaerobic digestion.

Ammoniacal nitrogen and long chain fatty acids (LCFA) are common inhibitors of the anaerobic digestion process. However, the interaction between these inhibitors has received little attention. Understanding the interaction between these inhibitors is important to optimise the operation of anaerobic digesters treating slaughterhouse waste or using fat, oil and grease (FOG) as co-substrate among others.

Considering syntrophic acetate oxidation and ionic strength improves the performance of models for food waste anaerobic digestion.

Current mechanistic anaerobic digestion (AD) models cannot accurately represent the underlying processes occurring during food waste (FW) AD. This work presents an update of the Anaerobic Digestion Model no. 1 (ADM1) to provide accurate estimations of free ammonia concentrations and related inhibition thresholds, and model syntrophic acetate oxidation as acetate-consuming pathway.

Purple phototrophic bacteria are outcompeted by aerobic heterotrophs in the presence of oxygen.

There is an ongoing debate around the effect of microaerobic/aerobic conditions on the wastewater treatment performance and stability of enriched purple phototrophic bacteria (PPB) cultures. It is well known that oxygen-induced oxidative conditions inhibit the synthesis of light harvesting complexes, required for photoheterotrophy. However, in applied research, several publications have reported efficient wastewater treatment at high dissolved oxygen (DO) levels.

Purple phototrophic bacteria for resource recovery: Challenges and opportunities.

Sustainable development is driving a rapid focus shift in the wastewater and organic waste treatment sectors, from a "removal and disposal" approach towards the recovery and reuse of water, energy and materials (e.g. carbon or nutrients).

Microalgae-bacteria consortia in high-rate ponds for treating urban wastewater: Elucidating the key state indicators under dynamic conditions.

On-line performance indicators of a microalgae-bacteria consortium were screened out from different variables based on pH and dissolved oxygen on-line measurements via multivariate projection analysis, aiming at finding on-line key state indicators to easily monitor the process. To fulfil this objective, a pilot-scale high-rate pond for urban wastewater treatment was evaluated under highly variable conditions, i.e.

Performance of a membrane-coupled high-rate algal pond for urban wastewater treatment at demonstration scale.

The objective of this study was to evaluate the performance of an outdoor membrane-coupled high-rate algal pond equipped with industrial-scale membranes for treating urban wastewater. Decoupling biomass retention time (BRT) and hydraulic retention time (HRT) by membrane filtration resulted in improved process efficiencies, with higher biomass productivities and nutrient removal rates when operating at low HRTs. At 6 days of BRT, biomass productivity increased from 30 to 66 and to 95 g·m·d when operating at HRTs of 6, 4 and 2.

Methanosarcina plays a main role during methanogenesis of high-solids food waste and cardboard.

Anaerobic digestion of food waste is a complex process often hindered by high concentrations of volatile fatty acids and ammonia. Methanogenic archaea are more sensitive to these inhibitors than bacteria and thus the structure of their community is critical to avoid reactor acidification. In this study, the performances of three different inocula were compared using batch digestion tests of food waste and cardboard mixtures.

Addition of granular activated carbon and trace elements to favor volatile fatty acid consumption during anaerobic digestion of food waste.

The effect of supplementing granular activated carbon and trace elements on the anaerobic digestion performance of consecutive batch reactors treating food waste was investigated. The results from the first batch suggest that addition of activated carbon favored biomass acclimation, improving acetic acid consumption and enhancing methane production. Adding trace elements allowed a faster consumption of propionic acid.

Accumulation of propionic acid during consecutive batch anaerobic digestion of commercial food waste.

The objective of this study was to test three different alternatives to mitigate the destabilizing effect of accumulation of ammonia and volatile fatty acids during food waste anaerobic digestion. The three options tested (low temperature, co-digestion with paper waste and trace elements addition) were compared using consecutive batch reactors. Although methane was produced efficiently (∼500ml CHgVS; 16l CHlreactor), the concentrations of propionic acid increased gradually (up to 21.

Kinetic study of dry anaerobic co-digestion of food waste and cardboard for methane production.

Dry anaerobic digestion is a promising option for food waste treatment and valorization. However, accumulation of ammonia and volatile fatty acids often occurs, leading to inefficient processes and digestion failure. Co-digestion with cardboard may be a solution to overcome this problem.

Cardboard proportions and total solids contents as driving factors in dry co-fermentation of food waste.

This study evaluated the influence of the co-substrate proportions (0-60% of cardboard in dry basis) and the initial total solid contents (20-40%) on the batch fermentation performance. Maximum hydrogen yields were obtained when mono-fermenting food waste at high solids contents (89mlH·gVS). The hydrogen yields were lower when increasing the proportions of cardboard.

Dry anaerobic digestion of food waste and cardboard at different substrate loads, solid contents and co-digestion proportions.

The increasing food waste production calls for developing efficient technologies for its treatment. Anaerobic processes provide an effective waste valorization. The influence of the initial substrate load on the performance of batch dry anaerobic co-digestion reactors treating food waste and cardboard was investigated.