This study investigated the acclimatization of Candidatus Brocadia, a freshwater Anammox species, to high nitrogen (up to 1.39 gN/L) and salinity (up to 14.3 gNaCl/L) loads in a semi-continuous sequencing batch reactor (ASBR). Throughout the experiment (360 days), the reactor demonstrated stable nitrogen removal performance, achieving a nitrite removal efficiency of over 99% even at nitrogen loading rates and salinity concentrations up to 0.72 gN/L/d and 14.29 gNaCl/L, respectively. The monovalent-to-divalent cation ratio (M/D) appeared as a potential factor influencing Anammox performance, with ratios exceeding 7 correlating with significant declines in activity, likely due to granule destabilization as predicted by the divalent cation bridging theory (DCBT). However, subsequent batch experiments revealed that salinity had a more pronounced inhibitory effect on nitrite consumption kinetics than the M/D ratio. These findings demonstrate the feasibility of the Anammox process for treating high-strength, saline effluents, such as those from agricultural systems. This study provides valuable insights into the operational strategies required to extend Anammox applications to complex wastewaters and emphasizes the importance of managing salinity and cation ratios for stable Anammox operation.

Biodegradable plastics have been developed as alternative materials to prevent the environmental damage of conventional plastics on ecosystems. However, their end of life depends on environmental conditions in which they are disposed of. Their management in anaerobic digestion (AD) remains a topic of debate and needs further investigation. This study assesses the behaviour of PHBV, a prominent bio-based biodegradable plastic, blended with cellulose fibres in mesophilic AD conditions. Results show that degradation depends on material characteristics such as its specific surface area and cellulose content. Nearly complete biodegradation is observed for 1 mm diameter powder and 67 % degradation for 2 × 2 cm films over 57 days of AD at 38 °C. Biodegradation is faster with higher cellulose content up to 40 %. Morphological, structural, and functional analyses indicate that biodegradation occurs primarily through surface erosion, resulting in reduced polymers molecular weight and crystallinity, along with shifts in functional ester groups. Specific microbial genera, such as Ruminofilibacter, Thiospeudomonas, and HN.HF0106, were abundant in the planktonic phase, while Ruminofilibacter, Clostridium sensu stricto 7, UCG.012, and Treponema dominated the biofilm during AD. This research aims to provide deeper understanding of PHBV degradation mechanisms in AD, crucial for effective management in such conditions.

Municipal wastewater treatment plants (WWTPs) are exposed to high concentrations of micropollutants that can impact conventional activated sludge treatment. The consequences of this include failure to meet discharge standards and the disintegration of flocs, leading to poor sludge settleability. This lab-scale study focuses on the influence of doxycycline, an antibiotic widely used against human and animal diseases, on protozoa, metazoa, and bacterial communities under sludge growing conditions. Doxycycline was added to the mixed liquor of a communal WWTP up to 0, 100, 200, and 400 mg of doxycycline L−1 and incubated in batch conditions for 23 days. The regular addition of nutrient and carbon sources was preformed every 2 days to prevent sludge starvation. Sludge growth, conductivity, and settleability were measured and compared to sludge microbial community structure, determined by microscopic observations and high-throughput 16S rDNA sequencing. The high doxycycline concentration negatively impacted settleability and correlated with a decrease in bacterial diversity and floc disintegration. The addition of doxycycline promoted the enrichment of Proteobacteria Brevundimonas sp., Luteibacter anthropi, and the Bacteroidetes Chryseobacterium massoliae. These species are known to be resistant to a wide spectrum of antibiotics, including tetracyclines. A study of a larger scale may be conducted based on this study’ results.

Phosphorus recovery from sewage sludge as secondary raw materials or as a direct P-rich fertiliser is one of the top frontrunner solutions to tackle Phosphorus (P) scarcity and depletion. However, the efficiency of this P recovery process greatly depends on its phosphorus dissolution potential, which in return relies on the phosphorus speciation in the sewage sludge. This article investigates the potential correlation between P speciation in sewage sludge and the iron-based P removal technologies used in sewage treatment plants (STP) through an innovative sequential extraction method based on the SEDEX method that distinguishes quantitatively between ferrous bound phosphate and ferric bound phosphate. XRD and SEM-EDX were also used to characterise P and Fe species in the studied sludge qualitatively. Principal component analysis showed that the sludge characterised by P bound to ferric iron (as the dominant P fraction) are mostly correlated with sludge produced from the CPR process (chemical phosphorus removal) and primary sludge. Moreover, sludge with a non-negligible amount of P bound to ferrous iron were correlated with sludge from the mixed EBPR-CPR process (Enhanced Biological P Removal assisted with CPR). However, Vivianite was only found in CPR sludge with Fe/P molar ratio higher than 0.6.

The always-increasing demand for fertilizers and the programmed limitation of phosphorus (P) resources makes P-recovery an increasing field of research. Pig slurry is a suitable waste stream for phosphorus recovery but, since P is present meanly in mineral forms, it requires a dissolution step prior to crystallization. This dissolution can be done chemically by addition of acid or biologically by fermentation of easily biodegradable organic matter. In this paper, biological acidification of pig slurry was studied in batch tests by adding sucrose or several agri-food waste as co-substrates. Fermentation of carrots, beans, and sucrose allowed the pig slurry dissolved P to increase from 7-10% of total-P at initial pH of 6.5-7.7 up to 60-90% when low pH 4-5.2 was reached. The pH decrease, metabolite production and microbial community dynamics were monitored and correlated to waste composition to get insight into the biological acidification mechanisms of pig slurry. We show that lactic acid fermentation occurs when the co-substrate has a high content in easily accessible carbohydrates and when a sufficient amount of waste is added to the slurry (50g-VS.L-1). Bioacidification results in an apparent decrease of bacterial diversity. The dominating clusters are Clostridiales and Streptococcus when moderate acidification occurs and Lactobacillus when pH drops below five. The successful acidification of digested and raw pig slurry by agri-food organic waste addition is promising for further developing inexpensive and low-tech P-recovery processes.

In the last two decades, phosphorus (P) recovery from sewage sludge liquors gained much interest for its high-quality product potential. However, the consistently reported constraints are the low phosphorus availability and the technical-economical difficulties to increase it through chemical acidification. This article discusses the mechanisms of phosphorus dissolution by the biological acidification process (Biological acidification or acidic fermentation) as an alternative to chemical acidification. In addition, we investigate the potential correlation between the phosphorus dissolution and iron phosphate speciation of several types of sludge from different sewage treatment plants and P removal technologies. The results show that the percentage of P dissolution by bioacidification is always higher than the P dissolution by chemical acidification at equal pH for all types of sludge except for the settled primary sludge. The highest P dissolution was recorded for the sludge from the Enhanced Biological P Removal process assisted with Chemical P Removal process (EBPR-CPR) with around 65% of P dissolution. Three mechanisms were identified as contributing to the increased P dissolution by bioacidification: P release by the Polyphosphate Accumulating Organisms (PAO), P dissolution by pH decrease, and P dissolution by a biological activity at acidic pH (3.7-4) that includes iron reduction and aluminum dissolution. The principal component analysis and Pearson's correlation indicate that P dissolution by bioacidification is negatively correlated with the P-bound to ferric iron, hence positively correlated with the P-bound to ferrous iron, which characterizes the sludge from the EBPR-CPR process. This study suggests that the choice of the P removal technology significantly influences the P recovery from sewage sludge liquors.

For small-scale farms, the development of rustic and cheap psychrophilic anaerobic digestion systems appears as an opportunity to treat manure, mitigate gaseous emissions and promote decentralized renewable energy production. However, the development of such processes is limited by our understanding of their start-up. In this research, we tested the ability of one mesophilic digestate and four different manure to be used as inoculum for the start-up of psychrophilic anaerobic digestion of swine slurry at 13 ?. The most efficient inoculum appeared to be a swine manure that had been stored for 2 months in a pit. After 9 months of acclimation, the corresponding reactor produced a maximum methane yield of 42L of CH4/kg Volatile Solide(substrate)/day and a CH4 volume of 125L of CH4/kg-Chemical Oxygen Demand(added). The maximum methane production expressed at 13 ? was between 55% and 68% of that obtained at 37 ?. Monitoring of the microbial community dynamics by high throughput 16S rDNA sequencing showed the smooth adaptation of manure microbial species, underlining the transient dominance of the acetogen syntroph candidatus Cloacimonas during acclimation and the enrichment in the Methanosaeta and Methanosarcina methanogens for an efficient methane production.

The treatment of a synthetic polluted gas containing seven volatile organic compounds (VOCs) was studied using a pilot plant in real industrial conditions. The process combined VOC absorption in silicone oil (PolyDiMethylSiloxane, i.e., PDMS), a biological regeneration of the PDMS in a two-phase partitioning bioreactor (TPPB), and a phase separation including settling and centrifugation. The TPPB was operated at a water/PDMS volume ratio of 75/25. The VOCs treatment performance was efficient during the entire test, corresponding to 10 PDMS regeneration cycles. The analysis of the content of the aqueous phase and PDMS confirmed that VOCs are progressively degraded until mineralization. The nitrogen consumption and the characterization of the microorganisms highlighted possible anoxic functioning of the biomass within the first decanter. Moreover, although the absorption and biodegradation performances were very satisfactory, the separation of all phases, essential for the PDMS recycling, was problematic due to the production of biosurfactants by the microorganisms, leading to the formation of a stable emulsion and foaming episodes. As a consequence, the packed column showed slight fouling. However, no significant increase in the pressure drop of the packed bed, as well as no significant impact on VOC absorption efficiency was observed.

To move today’s agricultural and urban systems towards tomorrow’s circular economy and respond to climate change, it is imperative to turn organic residues and wastewater into resourceful assets. This article discusses the changes that are needed in research to drive this paradigm shift and to go from a “losses and waste” situation to a “resource and opportunities” ambition. The current lines of research aim to maximise the use and value of biomass or organic residues and wastewater and propose new organisational schemes driven by technical innovations. Exploring the pathways to a sustainable future through many domains let us identify five challenges to structure the research efforts and find circular bioeconomy solutions for organic residues and wastewater: (1) proposing innovative processes and integrated multi-process systems; (2) promoting the emergence of multi-scale and cross-sectoral organisations; (3) developing multi-performance evaluation methods, (4) rethinking research–society intersections, and (5) enhancing research–legislation interactions. We end by outlining prospects for moving forward past current limitations: beyond increasing knowledge, research will continue its own transition. Our responsibility today is not to think about what we could do for a better world but what we should do to make our ever-changing world even better and more sustainable. Graphic Abstract

The treatment of a gaseous mixture of volatile organic compounds (VOC) using a large-scale installation combining a VOC absorption in silicone oil (PolyDiMethylSiloxane, i.e. PDMS), a biological regeneration of the PDMS in a two-phase partitioning bioreactor (TPPB) and a phase separation including settling and centrifugation was studied in real conditions on an industrial site. The TPPB was operated at a water/PDMS volume ratio of 75/25. The VOC treatment performance was satisfactory during the entire test (158 hours of operation or 10 PDMS regeneration cycles). The analysis of the content of the aqueous phase and PDMS confirmed that VOC are progressively degraded until mineralization. The nitrogen consumption and the characterization of the microorganisms highlighted anoxic functioning of the biomass of the pilot within the first decanter. Moreover, although the performances at the level of absorption and TPPB were very satisfactory, the separation of phases, essential for the recycling of the PDMS, encountered difficulties due to the production of biosurfactants by the microorganisms leading to the formation of a stable emulsion and foaming episodes. As a consequence, the packed column showed slight fouling. However, no significant increase in the pressure drop of the packed bed, as well as no significant impact on VOC absorption efficiency were observed. The phase separation step appears thus as the main problem to solve in order to further develop the treatment of hydrophobic VOC based on TPPB at industrial scale.

To face the increase of waste production and meet the energy demand of urban areas, municipal waste management systems should be rethought. Innovative solutions such as decentralised small-scale anaerobic digestion could be developed. This work presents the design, operation and performances of a new micro-scale anaerobic digester (AD) developed to degrade food waste (FW) in urban areas i.e. highly compact and with low water and energy demand. To meet these objectives, the new micro-scale AD is a semi-continuous and two-stage process built vertically to take advantage of the gravity to mix and move the digested matter instead of using mechanical devices. The first stage consists in a tubular reactor fed weekly with FW and periodically watered with leachate from the second stage reactor located below the tubular reactor. Results show that AD performances were highly correlated to the efficiency of hydric transfer between the tubular reactor and the leachate tank. Indeed, pH, volatile fatty acids and microbial community analysis showed that the hydrolysis occurred in the tubular reactor, while the methanogenesis step occurred in the leachate tank. Overall, the average methane production was 143 ± 87 N L/kg vs with an average methane content of 44 ± 10% and the operation mode of the process has still to be improved. Graphic Abstract

Advances in research and technological development in the field of wastewater treatment encourage the implementation of engineered autotrophic nitrogen removal (ANR) systems based on the coupling of partial nitritation (PN) and anaerobic ammonium oxidation (anammox). Such processes can be conducted in two independent dedicated reactors (i.e., two-stage system) or, alternatively, in the same reactor under limited aeration (i.e., one-stage system). In this investigation, both configurations were successfully tested using the sequencing batch reactor (SBR) technology. Processed wastewater was supernatant from a sewage sludge anaerobic digester containing about 1 g NH4+-N/L and 0.3 g PO4-P/L pre-conditioning of the supernatant through dilution and magnesium phosphates (e.g., struvite) precipitation favored the anammox process performance under both configurations. The N loading rate (NLR) applied in the PN reactor was <= 1.3 gN/(L.d) with nitrite production efficiencies of about 48%, whereas the N removal rate (NRR) in the anammox reactor was 0.43-0.56 g N/(L.d). On the other hand, in the one-stage reactor, the NRR was approximately 0.27 g N/(L.d). Estimated emissions of nitrous oxide (N2O) in such bioreactors ranged from 0.4 to 4.6% of the N loaded. Comparatively, similar NRRs were achieved for both reactor configurations but the one-stage system used a smaller reaction volume, ran at a lower NLR, and emitted N2O at a lower rate than the two-stage system. The microbial community in both systems was dominated by aerobic ammonium-oxidizing bacteria of the genus Nitrosomonas and the anammox species Ca. Brocadia sinica. (C) 2018 Elsevier Ltd. All rights reserved.

The data presented in this article regroup characterisation of organic matter and nutritional composition of 42 organic wastes and residues usually used as substrates for anaerobic digestion. Those wastes have different origins from agro-industrial, agricultural and urban sectors in France including: algae, slaughterhouse waste, fat, food waste, fruits and vegetables residues, green waste, slurry, manure, wastewater treatment plant sludge and agricultural residues. The properties of organic matter are distinguished between global parameters (pH, total solids, volatile solids, COD and BMP), organic matter fractionation (biochemical and Van Soest) and the main nutrients content (N, P, K, Mg, Ca and S).

This study provides an alternative solution for the bioremediation of a recalcitrant pharmaceutical micropollutant. Clofibric acid (CLA) was chosen as target molecule, because of its environmental persistence and resistance to wastewater treatment technologies. The aim of this study was to investigate the potential of a phenol-resistant Pseudomonas aeruginosa strain isolated from the activated sludge to degrade CLA. In order to evaluate the effect of acclimation process with glucose as carbon co-substrate, two protocols were performed, in which the transfer of the inoculum is carried out either in the exponential growth phase or in the decline phase. The results showed a removal efficiency of CLA of 35% when cells in the decline phase were used for inoculation. In contrast, a very low removal yield (10%) was achieved when cells harvested in the exponential phase were used as inoculum. This work is the first one reporting on the capability of this bacterium to remove this drug. The obtained data showed that the isolated strain is able to degrade target molecule and might be a promising agent for the elimination of this refractory compound.

ABSTRACT The aim of this study is to highlight the robustness and potentials of the anaerobic baffled reactor (ABR) configuration on keeping the microbial richness and diversity after starvation period of 7 days. The module at steady state operating conditions provided an average volumetric hydrogen production (VHP) of 0.2 ± 0.08 and 0.423 ± 0.5 l/d in the 1st and last compartment (C4). The VHP was gradually decreased from 0.2 to 0.003 l/d and from 0.423 to 0.1 l/d in compartments (C1 and C4) respectively during feed less period. However, the VHP was substantially increased up to 0.035 and 0.152 l/d in 1st (C1) and fourth compartment (C4) within 24 h, after reoperation of the ABR. Moreover, the H2 producers of Clostridiaceae, Ruminococcaceae, and Enterobacteriaceae families were dominant in the reactor after reoperation process. Quantitative polymerase chain reaction and next-generation sequencing methods results revealed that the microbial community structure was mainly composed of Proteobacteria, Firmicutes, Chloroflexi, Bacteroidetes, Planctomycetes, and Actinobacteria. The results showed the unique properties of the ABR configuration for keeping the microbial richness and diversity during feed less period.

Aerobic pre-treatment of food waste (FW) was performed at different oxygen concentrations (0%, 5%, 10% and 21%O-2) and different durations (1, 2, 3 and 4 days) to investigate its impact on biochemical and microbial community characteristics of the waste and its ability to improve anaerobic biodegradability. Whatever the duration, the highest effect of pre-treatment was observed at full aerobic pre-treatment (21%O-2) while 5%O-2 and 10%O-2 showed lower transformation performances. Biochemical variations at 21%O-2 were mainly a decrease of simple carbohydrates, volatile fatty acids (VFA) and low molecular weight water soluble compounds and an increase of high weight water soluble compounds. Microbial community analysis showed a clear modification of populations after 21%O-2 aerobic pre-treatment, changing from an initial dominance of lactic acid bacteria to a final dominance of VFA consumers (like Acetobacter) and a higher presence of Fungi. Enzymatic tests showed an increase of exoenzymes content and a higher presence of protein and carbohydrates degrading enzymes. Finally, the aerobic pre-treatment did not negatively impact methane potential of FW (496 NLCH4.kgVS(-1)) which remained unchanged after two days of pre-treatment at 21%O-2. These latter optimal pre-treatment conditions are proposed to be tested in future investigation of anaerobic digestion (AD) process with low inoculum to substrate ratio in order to assess their ability to avoid acidification risk during AD of FW. (C) 2018 Elsevier Ltd. All rights reserved.