Anaerobic Sewage Sludge Research Articles

Dead in the water – Role of relic DNA and primer choice for targeted sequencing surveys of anaerobic sewage sludge intended for biological monitoring

DNA-based monitoring of microbial communities that are responsible for the performance of anaerobic digestion of sewage wastes has the potential to improve resource recoveries for wastewater treatment facilities. By treating sludge with propidium monoazide (PMA) prior to amplicon sequencing, this study explored how the presence of DNA from dead microbial biomass carried over with feed sludge may mislead process-relevant biomarkers, and whether primer choice impacts such assessments. Four common primers were selected for amplicon preparation, also to determine if universal primers have sufficient taxonomic or functional coverage for monitoring ecological performance; or whether two domain-specific primers for Bacteria and Archaea are necessary. Anaerobic sludges of three municipal continuously stirred-tank reactors in Victoria, Australia, were sampled at one time-point. A total of 240 amplicon libraries were sequenced on a Miseq using two universal and two domain-specific primer pairs. Untargeted metabolomics was chosen to complement biological interpretation of amplicon gene-based functional predictions. Diversity, taxonomy, phylogeny and functional potentials were systematically assessed using PICRUSt2, which can predict community wide pathway abundance. The two chosen universal primers provided similar diversity profiles of abundant Bacteria and Archaea, compared to the domain-specific primers. About 16 % of all detected prokaryotic genera covering 30 % of total abundances and 6 % of PICRUSt2-estimated pathway abundances were affected by PMA. This showed that dead biomass in the anaerobic digesters impacted DNA-based assessments, with implications for predicting active processes, such as methanogenesis, denitrification or the identification of organisms associated with biological foams. Hence, instead of running two sequencing runs with two different domain-specific primers, we propose conducting PMA-seq with universal primer pairs for routine performance monitoring. However, dead sludge biomass may have some predictive value. In principal component analysis the compositional variation of 239 sludge metabolites resembled that of 'dead-plus-alive' biomass, suggesting that dead organisms contributed to the potentially process-relevant sludge metabolome.

Effect of Biological Pretreatment on Anaerobic Sewage Sludge Digestion: Using Growth Media for Methanogenic Bacteria and Kinetic Studies for Biogas Yield

Effect of Biological Pretreatment on Anaerobic Sewage Sludge Digestion: Using Growth Media for Methanogenic Bacteria and Kinetic Studies for Biogas Yield

Impacts of biochar derived from oil sludge on anaerobic digestion of sewage sludge: Performance and associated mechanisms

The addition of biochar is a promising strategy to improve methane production via strengthening direct interspecies electron transfer (DIET) in anaerobic digestion (AD) field. In this study, a novel oil sludge biochar (OSBC) prepared at 500/600/700 °C was used to investigate its dosage effects on performances of sewage sludge AD. The characterization results indicated that OSBC prepared at 600 °C had highest electron accepting and donating capacity, meanwhile, it also contained moderate functional groups such as CO, which were in favor of methane production. Therefore, the highest accumulative methane yield (143.96 mL (g VS)−1) accompanying with the fast consumption of volatile fatty acids (VFAs) was achieved at dosage of 1.2 g. Additionally, the conductivity and enzyme activity (electron transport system activity and coenzyme F420) of AD with OSBC addition were also enhanced. Microbial community structures manifested that the potential syntrophic microbes including archaea Methanothrix, Methanospirillum, and bacteria Comamonas, Petrimonas and Syntrophomonas were enriched by OSBC due to its large surface area and microelement such as iron, and contributed to the improved methane production. The results suggested that OSBC exhibited excellent practical application potential in enhancing anaerobic sewage sludge treatment and biogas productivity.

Process Improvement of Biogas Production from Sewage Sludge Applying Iron Oxides-Based Additives

Iron additives are effective in the anaerobic sewage sludge digestion process, but the composition and dosage of these additives are not precisely defined. This research investigates the effects of three iron oxides-based additives on the destruction of volatile solids, the production and quality of biogas, as well as the quality of the supernatant. Additive No 1 contained >41.5% of FeO and >41.5% of Fe2O3, additive No 2 contained ≥86% of Fe3O4, and additive No 3 contained ≥98% of Fe3O4. The best results were obtained by applying an iron oxides-based additive with a higher content of divalent iron oxide. The increase in efficiency of the VSs destruction was not significant and on average 2.2%. The increase in biogas production was on average 20% while the average increase in the content of methane in the biogas was 6.3%. Applying the additive, the reduction in the concentration of ammonium nitrogen in the supernatant was up to 28%, as well as a reduction in the concentration of phosphate phosphorus in the supernatant by up to 3.1 times could be expected compared to the case when the additive was not applied. The dose of additive No 1 was between 7.5 g/kg of dry solids and 15 g/kg of dry solids in the lab-scale test. The dose was specified in the full-scale test, and the recommended dose of the additive was 10 g/kg of dry solids to improve biogas production.

Biological Methanation in an Anaerobic Biofilm Reactor—Trace Element and Mineral Requirements for Stable Operation

Biological methanation of carbon dioxide using hydrogen makes it possible to improve the methane and energy content of biogas produced from sewage sludge and organic residuals and to reach the requirements for injection into the natural gas network. Biofilm reactors, so-called trickling bed reactors, offer a relatively simple, energy-efficient, and reliable technique for upgrading biogas via ex-situ methanation. A mesophilic lab-scale biofilm reactor was operated continuously for nine months to upgrade biogas from anaerobic sewage sludge digestion to a methane content >98%. To supply essential trace elements to the biomass, a stock solution was fed to the trickling liquid. Besides standard parameters and gas quality, concentrations of Na, K, Ca, Mg, Ni, and Fe were measured in the liquid and the biofilm using ICP-OES (inductively coupled plasma optical emission spectrometry) to examine the biofilms load-dependent uptake rate and to calculate quantities required for a stable operation. Additionally, microbial community dynamics were monitored by amplicon sequencing (16S rRNA gene). It was found that all investigated (trace) elements are taken up by the biomass. Some are absorbed depending on the load, others independently of it. For example, a biomass-specific uptake of 0.13 mg·g−1·d−1 for Ni and up to 50 mg·g−1·d−1 for Mg were measured.

Performance improvement of the osmotic microbial fuel cell by the pre-treatment of anaerobic sewage sludge using solenoid magnetic field

ABSTRACT This study explored the effect of a solenoid magnetic field (SOMF) as a pre-treatment on anaerobic sewage sludge (ASS) before using it in an osmotic microbial fuel cell (OMFC) as an inoculant. The ASS efficiency in terms of colony-forming unit (CFU) was improved ten times by applying SOMF compared to the control conditions. The obtained highest power density, current density, and water flux in the OMFC were 32.70 ± 5 mW·m−2, 135.13 ± 15 mA·m−2, and 4.24 ± 0.11 L·m−2h−1 respectively, for 72 h at 1 mT magnetic field. The coulombic efficiency (CE) and chemical oxygen demand (COD) removal efficiency were increased to 40–45% and 4–5% respectively, compared to un-treated ASS. Also, the start-up time of the ASS-OMFC system was almost reduced to 1–2 days based on open circuit voltage data. On the other hand, increasing the pre-treatment intensity of SOMF with time, it decreased the performance of OMFC. Also, the low intensity with increased pre-treatment time up to a specific limit enhanced the performance of OMFC.

Endocrine disrupting activity in sewage sludge: Screening method, microbial succession and cost-effective strategy for detoxification

Sewage sludge (SS) presents a high agronomic potential due to high concentrations of organic matter and nutrients, encouraging its recycling as a soil conditioner. However, the presence of toxic substances can preclude this use. To enable the safe disposal of this waste in agriculture, SS requires additional detoxification to decrease the environmental risks of this practice. Although some alternatives have been proposed in this sense, little attention is provided to eliminating endocrine-disrupting chemicals (EDCs). To fill this gap, this study aimed to develop effective and low-cost technology to eliminate EDCs from SS. For this, a detoxification process combining microorganisms and biostimulating agents (soil, sugarcane bagasse, and coffee grounds) was performed for 2, 4, and 6 months with aerobic and anaerobic SSs. The (anti-)estrogenic, (anti-)androgenic, retinoic-like, and dioxin-like activities of SSs samples were verified using yeast-based reporter-gene assays to prove the effectiveness of the treatments. A fractionation procedure of samples, dividing the target sample extract into several fractions according to their polarity, was conducted to decrease the matrix complexity and facilitate the identification of EDCs. A decrease in the abundance and microbial diversity of the SS samples was noted along the biostimulation with the predominance of filamentous fungal species over yeasts and gram-positive bacteria and non-fermenting rods over enterobacteria. Among the 9 EDCs quantified by LC-ESI-MS/MS, triclosan and alkylphenols presented the highest concentrations in both SS. Before detoxification, the studied SSs induced significant agonistic activity, especially at the human estrogen receptor α (hERα) and the human aryl hydrocarbon receptor (AhR). The raw anaerobic sludge also activated the androgen (hAR), retinoic acid (RARα), and retinoid X (RXRα) receptors. However, no significant endocrine-disrupting activities were observed after the SS detoxification, showing that the technology applied here efficiently eliminates receptor-mediated toxicity.

Biogas production and greenhouse gas mitigation using fish waste from Bragança/Brazil

The potential of biogas production using fish waste (FW) and its effect on greenhouse gas (GHG) reduction and on energy production were evaluated on this research. FW was co-digested with anaerobic sewage sludge (SS). The FW was collected in the city of Bragan?a, northern Brazil, in which the fish industry is the main activity with a FW production of approximately 9,000 kg?day-1. The experimental part included five SS/FW ratios, and in two experiments hydrogen was added. The experiments were carried out for 30 days and the effect on the cumulative biogas and methane yields were analyzed. The GHG reduction was estimated using the amount of FW not discarded in the Bragan?a open dump; and the electricity generation was calculated using the methane yield. Besides, two kinetic models were performed. The results presented a GHG reduction of 1,619 tons of CO2e and an electricity production of 372 to 956 MWh?year-1. The analysis of variance indicated that the methane production was highly dependent on the SS/FW ratios which ranged from 76 to 138 mL?gvs-1. Finally, this research showed the benefit of using FW to generate biogas and electricity while reducing GHG emissions in a city where there is no energy project.

The role of microbial ecology in improving the performance of anaerobic digestion of sewage sludge.

The use of next-generation diagnostic tools to optimise the anaerobic digestion of municipal sewage sludge has the potential to increase renewable natural gas recovery, improve the reuse of biosolid fertilisers and help operators expand circular economies globally. This review aims to provide perspectives on the role of microbial ecology in improving digester performance in wastewater treatment plants, highlighting that a systems biology approach is fundamental for monitoring mesophilic anaerobic sewage sludge in continuously stirred reactor tanks. We further highlight the potential applications arising from investigations into sludge ecology. The principal limitation for improvements in methane recoveries or in process stability of anaerobic digestion, especially after pre-treatment or during co-digestion, are ecological knowledge gaps related to the front-end metabolism (hydrolysis and fermentation). Operational problems such as stable biological foaming are a key problem, for which ecological markers are a suitable approach. However, no biomarkers exist yet to assist in monitoring and management of clade-specific foaming potentials along with other risks, such as pollutants and pathogens. Fundamental ecological principles apply to anaerobic digestion, which presents opportunities to predict and manipulate reactor functions. The path ahead for mapping ecological markers on process endpoints and risk factors of anaerobic digestion will involve numerical ecology, an expanding field that employs metrics derived from alpha, beta, phylogenetic, taxonomic, and functional diversity, as well as from phenotypes or life strategies derived from genetic potentials. In contrast to addressing operational issues (as noted above), which are effectively addressed by whole population or individual biomarkers, broad improvement and optimisation of function will require enhancement of hydrolysis and acidogenic processes. This will require a discovery-based approach, which will involve integrative research involving the proteome and metabolome. This will utilise, but overcome current limitations of DNA-centric approaches, and likely have broad application outside the specific field of anaerobic digestion.

THE INFLUENCE OF THE WAY OF SEWAGE SLUDGE TREATMENT ON AMMONIUM NITROGEN CONTENT IN THE RETURN WASTEWATER FLOW

Wastewater treatment facility receives, in addition to the influent, the return flow after sewage sludge treatment. Thus, the organic load on the facility increases as well as the nitrogen and phosphorus content load. There was studied the effect of different stages of sewage sludge treatment (sludge thickening, mechanical dewatering, storage on the grit bays and in the gathering ponds) on ammonium nitrogen content in the incoming flow. It is established that the most concentrated water by ammonium nitrogen is the return water from the gathering ponds, but the less concentrated is the supernatant water from sludge lagoons. Taking into account volume of the return flow the secondary ammonium nitrogen load from the every stage of sewage sludge treatment is calculated. It is revealed the seasonal and climatic impact on the gathering ponds return flow composition; it is shown that the biggest fluctuations occur in spring-summer period. The dependence of ammonium nitrogen content in the return flow on sludge thickening process time in the sludge lagoons is determined. The load contribution on the treatment facility by ammonium nitrogen in the return flow was 3% in the relation to this in the influent. The conclusion was made that with the existing technology of sewage sludge treatment the isolated scheme of return water treatment is not required. The comparative analysis on the effect of thermophilic and mesophilic conditions of anaerobic sewage sludge treatment on ammonium nitrogen content in the liquor was carried out. It was found that the higher ammonium nitrogen secondary load is created by the liquor of thermophilically treated sewage sludge: it is 16,4% versus 11,8% of mesophilically treated. Hence, the including of anaerobic sewage sludge treatment in the scheme significantly increases the load on treatment facility by ammonium nitrogen. In the conditions of cascade denitrification the distribution of incoming in the denitrification zones water flow is of great importance for providing required content of readily available organic substances. The change of ammonium nitrogen content in this flow will require the adjustment of its volume.

Fusion of Vermicompost and Sewage Sludge as Dark Fermentative Biocatalyst for Biohydrogen Production: A Kinetic Study

The present study explores the synergy between vermicompost and the anaerobic sewage sludge as inoculum for biohydrogen production using food waste as a substrate. Experiments were designed and performed in two phases of operation. In the first phase, the vermicompost (VC) was used as inoculum and food waste as substrate at three different organic loading rates of 10 gVS/L (VC1), 20 gVS/L (VC2), and 30 gVS/L (VC3). In the second phase of operation, the inoculums were combined with a proportion of 50% (VC+AS). The study showed an effective biohydrogen production of 20 gVS/L when the mixing ratio of vermicompost and anaerobic sludge was 50:50. The results inferred that effective synergy was observed between the combined consortia of the inoculum, which induces a more effective metabolic pathway for enhanced hydrogen production. H2 production was 33 mL/gVS (VC1), 48 mL/gVS (VC2), 35 mL/gVS (VC3), 46 mL/gVS (AS), and 50 mL/gVS (VC+AS). Heat pretreatment (100–120 °C) of the inoculum suppresses the methane-producing microorganisms and increases the hydrogen-producing microbes. In addition to hydrogen production, different metabolites are formed in the liquid phase, such as acetic acid, butyric acid, and propionic acid of 2.957 g/L, 4.286 g/L, and 2.123 g/L, respectively, with an energy content of 257 J/day with VC+AS. In addition, a kinetic model was studied for the cumulative hydrogen production curves using the modified Gompertz model, and the fit infers that the experimental data fitted well, with high coefficients of determination for VC+AS (R2 (G) > 0.99).

Anaerobic digestion of algal–bacterial biomass of an Algal Turf Scrubber system

This study investigated the anaerobic digestion of an algal–bacterial biofilm grown in artificial wastewater in an Algal Turf Scrubber (ATS). The ATS system was located in a greenhouse (50°54′19ʺN, 6°24′55ʺE, Germany) and was exposed to seasonal conditions during the experiment period. The methane (CH4) potential of untreated algal–bacterial biofilm (UAB) and thermally pretreated biofilm (PAB) using different microbial inocula was determined by anaerobic batch fermentation. Methane productivity of UAB differed significantly between microbial inocula of digested wastepaper, a mixture of manure and maize silage, anaerobic sewage sludge, and percolated green waste. UAB using sewage sludge as inoculum showed the highest methane productivity. The share of methane in biogas was dependent on inoculum. Using PAB, a strong positive impact on methane productivity was identified for the digested wastepaper (116.4%) and a mixture of manure and maize silage (107.4%) inocula. By contrast, the methane yield was significantly reduced for the digested anaerobic sewage sludge (50.6%) and percolated green waste (43.5%) inocula. To further evaluate the potential of algal–bacterial biofilm for biogas production in wastewater treatment and biogas plants in a circular bioeconomy, scale-up calculations were conducted. It was found that a 0.116 km2 ATS would be required in an average municipal wastewater treatment plant which can be viewed as problematic in terms of space consumption. However, a substantial amount of energy surplus (4.7–12.5 MWh a−1) can be gained through the addition of algal–bacterial biomass to the anaerobic digester of a municipal wastewater treatment plant. Wastewater treatment and subsequent energy production through algae show dominancy over conventional technologies.Graphical abstract

Possibilities of Biogas Upgrading on a Bio-Waste Sorbent Derived from Anaerobic Sewage Sludge

The development of biogas upgrading technologies is now an essential issue in recovering fuel-grade methane. Nowadays, trends in biogas upgrading include investigations of low-cost and renewable materials as sorbents for biogas enrichment to produce biomethane. Therefore, in this work, wastewater anaerobic sludge stabilized with calcium oxide was used as the bio-waste sorbent to capture carbon dioxide from biogas, employing a fixed bed column. The biogas flow rate was the parameter considered for examining the breakthrough responses. It was observed that breakthrough time decreases with increasing biogas inflow rate from 570 ± 10 min at 5 mL/min to 120 ± 12 min at 35 mL/min. The maximum sorption capacity of 127.22 ± 1.5 mg CO2/g TS of sorbent was estimated at 15 mL/min. Biomethane concentration in biogas increased from 56.5 ± 1.7 v% in the raw biogas to 98.9 ± 0.2 v% with simultaneous low carbon dioxide content of 0.44 ± 0.2 v%. A strong positive correlation (R2 = 0.9919) between the sorption capacity and the biogas flow rate was found in the range of biogas inflow rates between 5 mL/min and 15 mL/min. Moreover, the correlation analysis showed a strong negative relationship (R2 = 0.9868) between breakthrough time and the mass of carbon dioxide removal, and the biogas flow rates ranged from 10 mL/min to 20 mL/min.

Anoxic desulphurisation of biogas from full-scale anaerobic digesters in suspended biomass bioreactors valorising previously nitrified digestate centrate

Nitrification of centrate from anaerobic sewage sludge digestion presents a major opportunity as an electron acceptor in anoxic biogas biodesulphurisation. Nitritation and nitrification inhibition by free ammonia was detected at laboratory scale, but was avoided during the scale-up operation in a 4 m3 reactor treating ammonium loads up to 19 gN m−3 h−1. This nitrate-rich stream was fed to two pilot-scale suspended biomass bioreactors (SBBs) treating real biogas for 220 days. After an adaptation period of 21 days, nitrate and alkalinity concentrations in the liquid medium below 10 mgN L−1 and 100 mgCaCO3 L−1 were found to limit hydrogen sulphide (H2S) oxidation. Once controlled, 95% of the H2S was removed in SBB1 and 90% in SBB2, at a gas residence time (GRT) of 5.9 min, treating average values of 321 ± 205 ppmv and 457 ± 205 ppmv, respectively. Outlet H2S concentrations of 16 ± 24 ppmv in SBB1 and 46 ± 39 ppmv in SBB2 were obtained, which are below the requirements of biogas combustion heat and power engines. Unlike H2S, siloxanes were not removed with these GRTs. The results demonstrate the feasibility of the combined process for H2S treatment, potential valorisation of precipitated elemental sulphur and a reduction in the reagents currently used to control H2S.

Analysis of aerobic and anaerobic sewage sludge disposal concepts

The article aimed to analyze the concept of modernisation of sludge management prepared for an exemplary sewage sludge treatment plant. Four variants of solutions, based on different processes, aerobic (oxygenic), anaerobic or – aerobic – anaerobic, were discussed. The article presents the characteristics of essential elements of the proposed solutions. The technical and technological parameters of each of the variants are exposed. The expected capital expenditure and basic operating costs are presented. A cost-effectiveness analysis of the options has also been carried out. The analysed technological processes ensure obtaining hygienically and sanitary safe end products. They contribute significantly to minimising the amount of sewage sludge. The most economically efficient, with the lowest average annual costs, is the variant with the application of anaerobic thermo-philic-mesophilic sludge stabilisation. The highest average annual costs were obtained for the variant with drying and incineration of sludge.

Efficient substrates based on anaerobic sewage sludge biochar for tobacco seedlings in floating systems

ABSTRACT The objective was to develop efficient substrates, with increasing proportions of biochar derived from anaerobic sewage sludge (ASS-biochar) and regionally available raw materials, to produce tobacco seedlings (Nicotiana tabacum) in floating systems. Physical, hydraulic and chemical variables and the effects on tobacco plants were evaluated through an indoor experiment with seedling production. The experiment was conducted on trays in a floating hydroponic system in a randomized block design with four replications and eight plants per plot. The ASS-biochar showed environmental safety and agronomic efficiency in substrate composition, in particular with 50% to 90% ASS-biochar in the formulation. The best formulations positively affected the growth-related variables, showing similar or superior performance to the three commercial substrates (references). The ideal ranges of the substrate characteristics were: dry density: 420–520 kg m−3; total porosity: 60–75%; aeration space: 25–35%; easily available water: 9–12%; water buffering capacity: 3–5%; available water: 12–15%; remaining water: 20–25%; pH: 6.0–6.5; electrical conductivity: 1.4–2.3 mS cm−1. The development of substrates considering ASS-biochar, regional raw materials and ideal physical-chemical properties would prevent environmental pollution by generating value-added products to improve tobacco seedlings and expand the productivity and quality of tobacco worldwide.

Artificial neural network modeling of biochar enhanced anaerobic sewage sludge digestion

Despite the considerable amount of data generated with respect to biochar application in the anaerobic digestion of sewage sludge, there is a research gap for correlations linking biochar physico-chemical parameters to anaerobic digestion performance. In the current study, cumulative methane production (CMP) from anaerobic digestion of sewage sludge amended with biochar is modeled by an Artificial Neural Network (ANN) (2 hidden layers, 12 neurons each) based on data compiled from 51 published biomethane potential tests (BMP). The model reflects the effects of 13 operational parameters covering physico-chemical properties of biochar, sludge characterization and operating conditions. Various types of sewage sludge and biochar under both mesophilic and thermophilic conditions have been successfully modeled with an R2 of 0.9924. An importance analysis is conducted to evaluate the significance of the model input parameters to CMP. Results indicate that operating conditions are more significant to CMP and that CMP is strongly correlated with biochar physical properties and chemical composition where chemical composition has the dominant effect. Overall, this study proves that biochar physico-chemical parameters are correlated to CMP and enables its forecasting under unexamined conditions thus assisting in process optimization, scale up and techno-economic analyses without resorting to BMP tests.

Effects of Stepwise Temperature Shifts in Anaerobic Digestion for Treating Municipal Wastewater Sludge: A Genomic Study.

In wastewater treatment plants (WWTP), anaerobic digester (AD) units are commonly operated under mesophilic and thermophilic conditions. In some cases, during the dry season, maintaining a stable temperature in the digester requires additional power to operate a conditioning system. Without proper conditioning systems, methanogens are vulnerable to temperature shifts. This study investigated the effects of temperature shifts on CH4 gas production and microbial diversity during anaerobic digestion of anaerobic sewage sludge using a metagenomic approach. The research was conducted in lab-scale AD under stepwise upshifted temperature from 42 to 48 °C. The results showed that significant methanogen population reduction during the temperature shift affected the CH4 production. With 70 days of incubation each, CH4 production decreased from 4.55 L·g−1-chemical oxygen demand (COD) at 42 °C with methanogen/total population (M·TP−1) ratio of 0.041 to 1.52 L·g−1 COD (M·TP−1 ratio 0.027) and then to 0.94 L·g−1 COD ( M·TP−1 ratio 0.026) after the temperature was shifted to 45 °C and 48 °C, respectively. Methanosaeta was the most prevalent methanogen during the thermal change. This finding suggests that the Methanosaeta genus was a thermotolerant archaea. Anaerobaculum, Fervidobacterium, and Tepidanaerobacter were bacterial genera and grew well in shifted-up temperatures, implying heat-resistant characteristics.

Phosphitispora fastidiosa gen. nov. sp. nov., a new dissimilatory phosphite-oxidizing anaerobic bacterium isolated from anaerobic sewage sludge.

A new strictly anaerobic bacterium, strain DYL19T, was enriched and isolated with phosphite as the sole electron donor and CO2 as a single carbon source and electron acceptor from anaerobic sewage sludge sampled at a sewage treatment plant in Constance, Germany. It is a Gram-positive, spore-forming, slightly curved, rod-shaped bacterium which oxidizes phosphite to phosphate while reducing CO2 to biomass and small amounts of acetate. Optimal growth is observed at 30 °C, pH 7.2, with a doubling time of 3 days. Beyond phosphite, no further inorganic or organic electron donor can be used, and no other electron acceptor than CO2 is reduced. Sulphate inhibits growth with phosphite and CO2. The G+C content is 45.95 mol%, and dimethylmenaquinone-7 is the only quinone detectable in the cells. On the basis of 16S rRNA gene sequence analysis and other chemotaxonomic properties, strain DYL19T is described as the type strain of a new genus and species, Phosphitispora fastidiosa gen. nov., sp. nov.

Catalytic performance and periodate activation mechanism of anaerobic sewage sludge-derived biochar

Periodate (PI)-based advanced oxidation processes are a newly discovered approach for effective pollutant elimination. In this study, we demonstrated that biochar obtained from pyrolysis of anaerobic sewage sludge without any pretreatment can be used for PI activation. The biochar obtained at 800 °C (SBC-800) exhibited the best PI activation capacity using acid organic II (AO7) as substrate. The PI activation was strongly dependent on pH and exhibited the highest AO7 removal rate at pH 3.0. Meanwhile, the anti-interference capacity with common wastewater components and reusability of the SBC-800/PI system were confirmed. Combined with the results of chemical quenching, reactive oxygen species (ROS) trapping, X-ray photoelectric spectroscopy (XPS), electrochemical and density function theory (DFT)-based calculations, singlet oxygen production and electron transfer mediated by the SBC-800-PI complex were the dominant AO7 oxidation mechanisms. This study provides easily prepared catalysts for PI activation and paves the way for solid waste recycling and reuse.