Anaerobic System Research Articles

Bovine colostrum-derived extracellular vesicles may accelerate the growth of Akkermansia muciniphila by regulating energy metabolism in intestinal anaerobic coculture system

Bovine colostrum-derived extracellular vesicles may accelerate the growth of Akkermansia muciniphila by regulating energy metabolism in intestinal anaerobic coculture system

Upcycling of nutrients from kitchen waste: Integration of anaerobic digestion system and microbial protein production system

To upcycle the nutrients from kitchen waste (KW), an integrated system consisting of anaerobic digestion (AD) reactor and microbial protein (MP) production reactor was established in this study. The subsystem I (AD system) demonstrated an efficient bio-energy production (282.37 mL CH4/g VS), with 553.54 mg/L of NH4+-N remained in the digestate. The subsystem II (MP production system) utilized the nitrogenous constituents of the digestate, with 2.04 g/L MP production. In order to further enhance the recovery efficiency, C/N ratio in the subsystem II was studied. NH4+-N recovery efficiency was 23.08% higher after C/N ratio optimization along with 0.24 g/L increment on MP production. Over 0.7 g/L of essential amino acids was obtained, according with the qualitative necessary for the feeds. Also, the key enzyme abundance of CO2 releasing and amino acid biosynthesis was obviously increased with max. 55.21%. Meanwhile, the integrated system was profitable via a simplified economic assessment.

Treatment of pulp and paper mill effluent through combined aerobic and anaerobic suspended fixed-bed bioreactor.

This study explored using ultrafiltration (UF) membranes to treat pulp and paper mill wastewater, implementing a novel Taguchi experimental design to optimize operating conditions for pollutant removal and minimal membrane fouling. Researchers examined four factors: pH, temperature, transmembrane pressure, and volume reduction factor (VRF), each at three levels. Optimal conditions (pH10, 25°C, 6bar, VRF 3) led to a 35% reduction in flux due to fouling and high pollutant rejections: total hardness (83%), sulfate (97%), spectral absorption coefficient (SAC254) (95%), and chemical oxygen demand (COD) (89%). Conductivity had a lower rejection rate of 50%. Advanced imaging techniques like atomic force microscopy (AFM) and scanning electron microscopy (SEM) revealed reduced membrane fouling under these conditions. The Taguchi method effectively identified optimal conditions, significantly improving wastewater treatment efficiency and promoting environmental sustainability in the pulp and paper industry. PRACTITIONER POINTS: This study optimized UF membrane conditions for pulp and paper mill wastewater, reducing fouling and enhancing pollutant removal, offering practical strategies for industrial treatment. AFM and SEM provided key insights into membrane fouling and mitigation, promoting real-time diagnosis and optimization for enhanced treatment efficiency. Prioritizing anaerobic fixed-bed systems in wastewater treatment is beneficial for achieving high COD removal efficiency. Optimizing hydraulic retention time (HRT) in these systems can further improve their overall effectiveness and sustainability.

Long-term performance and activity study of a two-stage anaerobic EGSB reactors system treating complex and toxic industrial wastewater.

Anaerobic treatment of industrial wastewater using upflow anaerobic reactors is an extended trend due to its high efficiency and biogas production potential, but its implementation in some sectors is limited due to the complexity and toxicity of the wastewaters. In this study, a two-stage expanded granular sludge bed (EGSB) reactors system has been investigated at both bench and pilot scale for the treatment of complex and toxic real wastewater from a petrochemical industry. The effect of different operational parameters including organic loading rate (OLR), hydraulic retention time (HRT) and influent characteristics over COD removal and biogas production and composition have been studied. Additionally, biomass specific methanogenic activity (SMA) and wastewater toxicity have been evaluated after long-term operation. Optimum total HRT of 24 h has been determined resulting in total COD and SO4 2- removal of 56.30 ± 5.25% and 31.68 ± 14.71%, respectively, at pilot scale, and average biogas production of 93.47 ± 34.92 NL/day with 67.01 ± 10.23 %CH4 content and 5210.11 ± 6802.27 ppmv of H2S. SMA and toxicity tests have confirmed inhibitory and toxic effects of wastewater over anaerobic biomass with average maximum inhibition of 65.34% in the unacclimated anaerobic inoculum while chronic toxicity produced a decrease of an order of magnitude in SMA after 600 days of operation. This study demonstrates the feasibility of applying an anaerobic treatment to this wastewater using EGSB reactors between a 0.97-1.74 gCOD/L/day OLR range. Nonetheless, periodic reinoculation would be necessary for long-term operation due to chronic toxicity of the wastewater exerted on the anaerobic biomass. PRACTITIONER POINTS: A two-stage EGSB reactors system has been operated at bench and pilot scale to treat complex and toxic petrochemical wastewater. Optimal total HRT of 24 h resulted in average COD removal ranging from 40% to 60%. SMA and toxicity tests have been performed to study long-term acclimation, detecting an activity depletion of an order of magnitude.

Hubungan Asupan Zat Gizi Makro dan Status Gizi dengan Kebugaran Jasmani Atlet Cabang Olahraga Permainan

Background: Physical fitness is a person ability to carry out physical activities. Physical fitness is very important for athletes to improve athlete performance and athlete quality. Sports with aerobic and anaerobic systems require cardiovascular endurance (VO2 max). Physical fitness will run well with adequate energy and macronutrient intake. Objectives: This study aims to determine the relationship between energy intake, macronutrients and nutritional status with the physical fitness (VO2 Max) of athletes in gaming sports at BPPLOP Central Java. Method: The research was conducted using analytical observation with a cross sectional design. The research sample was 47 people using a total sampling technique. Data on athletesmacronutrient intake uses the 3x24 hour food recall method, physical fitness (VO2 max) measurements use the bleep test. Data analysis was carried out using the Pearson Correlation Test. Results: The results of the Pearson correlation test showed that there was no significant relationship between energy intake (p=0.921 R=-0.015), protein (p=0.276 R=-0.162), fat (p=0.778 R=-0.042), and carbohydrates (p= 0.923 R=0.015) on athletes' physical fitness (VO2 max). Conclusion: It was found that there was a significant relationship between nutritional status (p=0.021 R=-0.335) and physical fitness (VO2 max) of game sports athletes at BPPLOP CentralJava.Key words : carbohydrates, energy, nutritional status, physical fitness (VO2 Max), protein

Cellulosic ethanol stillage for methane production by integrating single-chamber anaerobic digestion and microbial electrolysis cell system

Anaerobic digestion provides a solution to the inefficient use of carbon resources caused by improper disposal of corn stover-based ethanol stillage (CES). In this regard, we developed a single-chamber anaerobic digestion integrated microbial electrolysis cells system (AD-MEC) to convert CES into biogas while simultaneously upgrading biogas in-situ by employing voltages ranging from 0 to 2.5 V. Our results demonstrated that applying 1.0 V increased the CH4 yield by 55 % and upgraded the CH4 content in-situ to 82 %. This voltage also promoted the well-formed biofilm on the electrodes, resulting in a 20-fold increase in current. However, inhibition was observed at high voltages (1.5–2.5 V), suppressing syntrophic organic acid-oxidizing bacteria (SOB). The dissociation between SOB and methanogens led to accumulation of propionic and butyric acid, which, in turn, inhibited methanogens. The degradation of CES was accelerated by unclassified_o_norank_c_Desulfuromonadia on the anode, likely leading to an increase in mixotrophic methanogenesis due to the synergistic interaction among Aminobacterium, Sedimentibacter, and Methanosarcina. Furthermore, the enrichment of electroactive bacteria (EB) such as Enterococcus and Desulfomicrobium likely facilitates direct interspecies electron transfer to Methanobacterium, thereby promoting the conversion of CO2 to CH4 through hydrogenotrophic methanogenesis. Rather than initially stimulating the EB in the bulk solution to accelerate the start-up process of AD, our study revealed that applying mild voltage up to 1.0 V tended to mitigate the negative impact on the original microorganisms, as it gradually enriched EB on the electrode, thereby enhancing biogas production.

The tasks of the stages of the annual cycle, the solution of which is the basis for improving physical qualities, which ensures the effectiveness of middle-distance running of athletes at the stage of specialized basic training

The current training method focuses on the athlete at the stage of specialized basic training to further achieve a consistent level of development of special strength, as well as basic strength and strength abilities, It is fundamentally necessary to thoroughly understand the technical and tactical abilities of a mid-distance runner in the minds of a high level for The highest level of basic tasks is to achieve a high level of diversity and the interconnection of all types of preparation - physical, technical, tactical, psychological, moral-volitional, etc. Based on periodization systems, we improved the annual training macrocycle for middle-distance runners in the third year of specialized basic training, which includes: 2 autumn-winter and spring-summer macrocycles, 6 main periods and 16 training stages, which include 18 mesocycles and 52 microcycles. Considering the stages of preparation of the annual training cycle as the basis of the training process of middle-distance runners at the stage of specialized basic training, we developed groups of exercises with different predominant orientation, and on this basis, model microcycles of each stage were built depending on the tasks. On the basis of the annual training macrocycle of qualified middle-distance runners in the third year of training at the stage of specialized basic training, the main tasks of the stages of the annual training cycle of different predominant orientations were developed, which are the basis for improving the components of physical qualities. The developed tasks of the stages of the annual training cycle are aimed at increasing the capabilities of the aerobic system, the aerobic-anaerobic system, as well as the anaerobic energy supply system, which will make it possible to lay an aerobic-anaerobic base on which middle-distance runners will successfully perform large volumes of special work, carry loads more easily, and recover faster after them at the stage of specialized basic training.

Performance evaluation and microbial community analysis of a continuous stirred tank reactor–anaerobic ceramic membrane bioreactor system for practical swine wastewater treatment

To treat swine wastewater from a practical piggery, a continuous stirred tank reactor (CSTR)–anaerobic ceramic membrane bioreactor (AnCMBR) was operated for 201 days. A high chemical oxygen demand (COD) removal efficiency of 95 % and biogas production rate of 0.31 L/L·d were achieved at an organic loading rate (OLR) of 1.19 g-COD/L·d. Although the free ammonia concentration reached a maximum of 200 mg/L during the last operational phase, no evident inhibitory effect on AnCMBR performance was observed. Microbial community analyses indicated that six bacterial phyla were responsible for the hydrolysis, acidification, and fermentation of organics and environmental stabilization. Hydrotrophic methanogenic archaea were dominant, indicating that the main methane production pathway involved the use of H2 and CO2 as substrates. The results demonstrated that CSTR–AnCMBR systems exhibit excellent organics removal performance and energy recovery at high organic concentrations and possess strong anti-shock ability. Thus, they represent alternative green and sustainable anaerobic technologies for practical swine wastewater treatment.

Exploring the promoting behavior of weak electric mediation on indole and pyridine biodegradation under anaerobic condition

Indole and pyridine, which are highly produced refractory compounds in the industrial wastewater, exhibit poor degradation capabilities in natural environments. In this study, we developed an anaerobic digestion system coupled with weak electric mediation (ED), and investigated the promoting effect of weak electricity on indole and pyridine biodegradation. The degradation characteristics were systematically explored, and the results showed that the degradation rate and mineralization of indole and pyridine were significantly enhanced, the production of CH4 was increased 1.4-fold, and the optimal voltages were 1.0 V and 0.8 V in the ED, respectively. Moreover, simultaneous removal of carbon and nitrogen was achieved. Gas chromatography–mass spectrometry analysis verified the transformation products, and possible pathways were proposed. Several byproducts of indole and pyridine were identified, with oxindole and glutaric dialdehyde being the main metabolites, respectively. Additionally, density functional theory (DFT) analysis was performed to investigated the radical indices and stabilities of the molecules to further confirm the degradation pathway. Microbial structure analysis demonstrated that the electrically mediated enhanced metabolism and activity of functional microbes, led to the promotion of indole and pyridine mineralization. Moreover, such species as degrading bacteria (Alicycliphilus, Shinella) and electroactive bacteria (Achromobacter), anaerobic ammonia-oxidizing bacteria (SM1A02), and denitrifying bacteria (Thiobacillus) coexisted. This study demonstrates that weak electric mediation is a promising methodology for enhancing the removal of indole and pyridine from wastewater under anaerobic conditions.

Impact of additives on syntrophic propionate and acetate enrichments under high-ammonia conditions

High ammonia concentrations in anaerobic degradation systems cause volatile fatty acid accumulation and reduced methane yield, which often derive from restricted activity of syntrophic acid-oxidising bacteria and hydrogenotrophic methanogens. Inclusion of additives that facilitate the electron transfer or increase cell proximity of syntrophic species by flocculation can be a suitable strategy to counteract these problems, but its actual impact on syntrophic interactions has yet to be determined. In this study, microbial cultivation and molecular and microscopic analysis were performed to evaluate the impact of conductive (graphene, iron oxide) and non-conductive (zeolite) additives on the degradation rate of acetate and propionate to methane by highly enriched ammonia-tolerant syntrophic cultures derived from a biogas process. All additives had a low impact on the lag phase but resulted in a higher rate of acetate (except graphene) and propionate degradation. The syntrophic bacteria ‘Candidatus Syntrophopropionicum ammoniitolerans’, Syntrophaceticus schinkii and a novel hydrogenotrophic methanogen were found in higher relative abundance and higher gene copy numbers in flocculating communities than in planktonic communities in the cultures, indicating benefits to syntrophs of living in close proximity to their cooperating partner. Microscopy and element analysis showed precipitation of phosphates and biofilm formation in all batches except on the graphene batches, possibly enhancing the rate of acetate and propionate degradation. Overall, the concordance of responses observed in both acetate- and propionate-fed cultures highlight the suitability of the addition of iron oxide or zeolites to enhance acid conversion to methane in high-ammonia biogas processes.Key points• All additives promoted acetate (except graphene) and propionate degradation.• A preference for floc formation by ammonia-tolerant syntrophs was revealed.• Microbes colonised the surfaces of iron oxide and zeolite, but not graphene.Graphical

Enhanced methane production from anaerobic wastewater treatment by carbon nanotubes: Surface defect mediated interfacial electron transfer

Interfacial electron transfer, a crucial process in direct interspecies electron transfer (DIET) between exo-electrogenic microorganisms and conductive materials, has played a vital role in enhancing methane production in anaerobic wastewater treatment. To improve interfacial electron transfer, the construction of surface defect has been identified as an effective approach. In this study, a range of metals and non-metals were used to dope carbon nanotubes (CNTs), which were served as the conductive materials and added into anaerobic wastewater treatment systems. The effect of surface defect of CNTs on methane production were investigated. The results demonstrated that all the doped CNTs can significantly increase methane production rate in anaerobic systems. Among them, boron and iron doped CNTs (B-CNTs and Fe-CNTs) exhibited the most promising performance as non-metal and metal doped CNTs. The addition of B-CNTs and Fe-CNTs led to impressive increase of 101.6% and 149.8% in the methane production rate of the anaerobic systems. Furthermore, this study elucidated the underlying mechanisms responsible for the enhanced methane production in the anaerobic wastewater treatment with doped CNTs. The introduction of doped CNTs enriched exo-electrogenic bacteria and archaea, thereby promoting the DIET process. Additionally, the CNTs also acted as the capacitor, storing and discharging electrons, which contributed to the maintenance of a stable methane production in anaerobic wastewater treatment.

Model based analysis of trace metal dosing strategies to improve methane yield in anaerobic digestion systems

Favourable effects of trace metals (TMs) on regulating anaerobic digestion (AD) performance are extensively utilised to improve methane yield. This study discusses a model-based approach to find out the best TM dosing strategies. The model has been applied to compare continuous, preloading, pulse dosing and in-situ loading. Simulations were also carried out to comprehend appropriate dosing form, dosing time and quantity of metals to be dosed. Model results show that the best way to dose TMs is repeated pulse dosing at low concentration levels in the optimum range with high frequency. Best dosing strategy for the system in this study was found to be 5 µM pulse loading at 5 days intervals as it gave maximum methane production and low effluent metal loss. Preferable dosing form depends on reactor configuration and this has been verified after model calibration with experimental data. Easily dissociable metal chlorides are ideal for continuous reactors.

Measures for Achieving Carbon Neutrality in Domestic Wastewater Treatment Plants

Objectives : In modern society, domestic wastewater treatment plants are essential infrastructure. However these facilities are also major sources of significant greenhouse gas emissions. To mitigate the climate crisis and move towards a sustainable society, reducing greenhouse gas emissions from domestic wastewater treatment plants is an urgent task. Achieving this requires the integrated application of technological improvements and institutional measures.Methods : Fundamental strategies for reducing greenhouse gas emissions from domestic wastewater treatment plants include detailed categorization and quantification of emission sources, the implementation of greenhouse gas reduction facilities, and the enforcement of water usage reduction policies. This study uses modeling software to estimate the detailed emissions of greenhouse gases generated during the domestic wastewater treatment process. Additionally, it establishes the baseline treatment process of the domestic wastewater treatment plant and analyzes the greenhouse gas reduction effects of each facility by incorporating technological methods such as anaerobic digesters and combined heat and power (CHP) systems. Furthermore, it evaluates the impact of reducing water usage through water footprint (WF) labeling on greenhouse gas emissions from the domestic wastewater treatment plant as an institutional approach.Results and Discussion : In scenario analysis, the implementation of anaerobic digesters results in a 6.7% reduction in greenhouse gas emissions compared to the baseline, while the addition of CHP systems to anaerobic digestion is predicted to reduce emissions by 29.1%. By integrating CHP systems with anaerobic digesters and applying WF labeling, a reduction of 38.3% in greenhouse gas emissions from the domestic wastewater treatment plant compared to the baseline is anticipated. These results demonstrate the significant role of implementing anaerobic digesters, CHP systems, and WF labeling in achieving the carbon neutrality goal of domestic wastewater treatment plants.Conclusion : The integrated application of technological methods, institutional approaches, and detailed emission calculations through process modeling can be considered crucial for reducing greenhouse gas emissions from domestic wastewater treatment plants.

Iron-retrofitted anaerobic baffled reactor system for rural wastewater treatment: Stable performance of nutrients removal with phosphorus recovery and minimal sludge production

An iron-retrofitted anaerobic baffled reactor (ABR) system was developed for the effective treatment of rural wastewater with reduced maintenance demand and aeration costs. Average removal efficiencies of chemical oxygen demand, total nitrogen and total phosphorus of 99.4%, 62.7% and 92.6% were achieved respectively, when the ABR system was operating at steady state. With effective bioreduction of FeIII in the anaerobic chambers, phosphorus was immobilized in the sludge as vivianite, the sole phosphorus-carrying mineral. The FeIII in the recirculated sludge induced Feammox in the ABR reactor, contributing 14.8% to total nitrogen removal. Biophase separation and enrichment of microorganisms associated with iron and nitrogen transformations were observed in the system after Fe dosing, which enhanced the removal of pollutants. The coupling of Feammox and vivianite crystallization to remove nitrogen and phosphorus in an iron-retrofitted ABR would appear to be a promising technology for rural wastewater treatment.

Study of SPALD-T Implementation Based on Regulation of the Minister of Public Works and Public Housing Number 04/PRT/M/2017 (Case Study: Surabaya City)

PUPR Ministerial Decree No. 4 of 2017 states that SPALD development is based on 6 criteria including population density, groundwater depth, soil permeability, financing capacity, land slope, and specific areas. If it refers to one of these criteria, Surabaya City is potentially obliged to implement SPALD-T. This research aims to examine how SPALD-T can be implemented in Surabaya City in terms of technical and institutional aspects. The research method was carried out using descriptive analysis with additional mapping using GIS. Descriptive analysis was carried out to describe the condition of Surabaya City. Meanwhile, mapping is used to determine priority locations that can be implemented by the relevant agencies to implement SPALD-T in Surabaya City. Based on the studies that have been carried out, Surabaya City is included in the areas that need to implement SPALD-T in wastewater management efforts. Furthermore, from an institutional perspective, Surabaya City is ready to implement SPALD-T because it has mapped out the tasks between planning, construction, operations and maintenance. The scheme that can be implemented in Surabaya City is SPALD-T for residential areas with a service area of 1 RT 1 WWTP using an anaerobic processing system.

The important role of high sludge concentration in anaerobic biological systems with low COD/SO42- sulfate-containing wastewater predicted by machine learning: Insights from microbial community and metabolic pathways

In anaerobic biological systems, sulfate reduction efficiency is influenced by multiple factors synergistically, particularly under low chemical oxygen demand-to-sulfate ratio (COD/SO42-) conditions. Enhancing sulfate reduction efficiency under low COD/SO42- conditions is challenging due to the deficiency of electron donors. In this study, two anaerobic systems were operated with a gradual decrease in COD/SO42-. The primary objective was to investigate the correlations among various influential factors, the efficacy of sulfate reduction, and the progression of microbial communities. The results showed that even with a decrease in COD/SO42- to 0.1, the sulfate reduction efficiency could reach 70% under high sludge concentration. Machine learning predictions identified sludge concentration as the most influential factor under low COD/SO42- conditions. The functional gene analysis confirmed that the sulfate reduction under high sludge concentration was primarily governed by the dissimilatory pathway and exhibited minimal reliance on COD/SO42-. These findings provide theoretical support and a novel approach for the anaerobic biological treatment of sulfate-containing wastewater under low COD/SO42- conditions.

A hybrid building-integrated solar-powered anaerobic digestion system: Energy, economic, and environmental analysis in Morocco

In this study, we propose a hybrid solar-anaerobic digestion system for a cleaner energy in the building sector. This system offers sustainable treatment of organic waste, utilizing waste generated by residential buildings. We conducted an investigation into the energy, economic, and environmental aspects of integrating a hybrid solar anaerobic digester treating kitchen waste (KW) and blackwater (BW) into Moroccan residential buildings under different climatic conditions. Two building categories were considered: buildings compliant with Moroccan thermal regulations of construction (MTRC), and non-compliant buildings, which represent the majority in Morocco. Results indicate that the proposed hybrid system, utilizing only waste generated by the building, can, on average, satisfy approximately 26 % of the total heating, cooling, and electricity needs of the considered MTRC non-compliant buildings. As for the MTRC compliant buildings, about 30 % of the total energy needs are met. Simulation outcomes also demonstrate that increasing the quantity of organic waste enhances system autonomy, allowing it to meet 100 % of the energy demand of the studied buildings. Excess heat energy generated by the hybrid system was allocated to the buildings' thermal and domestic hot water demands. Furthermore, the study highlights the significant influence of fixed costs and waste quantity on the system's profitability. Environmental benefits were also evident, with the designed hybrid system reducing CO2 emissions by 66 % compared to using grid electricity.

Scale-up of plug-flow reactors in anaerobic treatment of agro-industrial wastes

This study is aiming to evaluate the optimization potential of anaerobic digestion systems for the treatment of complex agro-industrial wastes at an industrial scale. In previous work, the performance of a 20 L pilot-scale Plug Flow Reactor (PFR) that was able to operate at Organic Loading Rates (OLRs) of up to 25 kg Chemical Oxygen Demand (COD) m−3 d−1, was demonstrated. This concept was then successfully transferred in a semi-industrial scale PFR of a volume equal to 50 m3, and the optimal operational parameters were evaluated. The construction of a full industrial scale facility followed, utilizing initially a 380 m3 PFR. Since PFR systems in practice do not behave ideally, due to short Length to Diameter ratio (L/D) and/or higher axial dispersion, the ideal PFR behavior was compared with real data of the non-ideal industrial-scale system; a performance reduction of 25–30 % was detected. However, the disadvantage of the non-ideal behavior of PFRs can be overcome by the cascaded arrangement of two such reactors (2 × 380 m3 PFRs), leading to a total volume reduction of 35 %, as depicted by experimentation on the industrial scale cascaded PFRs. The optimal design parameters for the PFRs are provided.

A novel strategy combining hydrogenotrophic methanogens' bioaugmentation and biochar biostimulation for simultaneous polycyclic aromatic hydrocarbon biodegradation and bioenergy recovery.

A novel strategy combining bioaugmentation using methanogenic archaea and biostimulation using biochar was proposed for the first time to obtain simultaneous improvement of mixed PAHs' anaerobic biodegradation and bioenergy production. The results showed that the addition of PHAs immediately resulted in inhibition in methane production and accumulation of VFA, indicating that PHAs are more toxic to methanogens than the acetogenic bacteria. The coupling of biochar with hydrogenotrophic methanogen alleviated the inhibitory effects of PAHs, allowing the anaerobic fermentation system to recover its methane production capability rapidly. Compared to the Fe3+ + bioaugmentation group, the biochar + bioaugmentation group exhibited a 7.5% higher restored cumulative methane production. This coupling strategy ultimately facilitated the degradation of most PAHs, achieving a removal rate of over 90%. Moreover, the coupled biochar and bioaugmentation induced significant changes in the archaeal community structure. Direct interspecies electron guilds (i.e., Streptococcus and Methanosarcina) were enriched in the presence of biochar and bioaugmentation, responsible for prominent PAH removal and methane recovery. This study demonstrated the feasibility of simultaneous PAH biodegradation and bioenergy production using electron acceptor and enriched microorganisms.

Anaerobic recovery of vivianite from waste-activated sludge through combined sludge pre-fermentation and agroforestry biomass-based biochar

The recovery of vivianite through the anaerobic digestion of waste-activated sludge has attracted considerable attention due to its operational simplicity and the high economic value of vivianite. This study concentrated on the recovery of vivianite from anaerobic fermentation systems through a strategy combining sludge pre-fermentation with the waste agricultural and forestry biomass-derived biochar (ZBC). In-depth analyses of the structure and functionality of ZBC were conducted using techniques such as Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. The sediment produced after the experiment and the changes in microbial community composition were characterized. The results indicated that pre-fermentation promoted phosphorus release, enhancing the synthesis of vivianite while selectively enriching respiratory and fermentative Fe (III)-reducing microorganisms. When FeOOH was used as the Fe (III) source, ZBC, through its dual action of redox functional groups and graphitization structure, increased the Fe2+ production by 243.6 % in the system dominated by respiratory Fe (III)-reducing bacteria. The optimal dosage of ZBC for the simultaneous recovery of vivianite resources and methane energy was 2.5 g/L. The combined application of pre-fermentation and ZBC provides a novel approach for the efficient recycling of vivianite and offers new insights into the reuse of agroforestry waste biomass resources.