Alkaline Fermentation Research Articles

Upgrading Denitrification by Optimal Adsorption of SCFAs from Sludge Alkaline Fermentation Liquid by Acid-Modified Sepiolite

Upgrading Denitrification by Optimal Adsorption of SCFAs from Sludge Alkaline Fermentation Liquid by Acid-Modified Sepiolite

Carbon sources influence on heterotrophic ammonia assimilation: Performance and mechanism

Different carbon contents of organic carbon sources can be used as the reaction substrates of heterotrophic ammonia assimilation (HAA), which effectively dominates the recovery of available nutrients in wastewater. However, the influences of organic carbon sources on nutrient metabolism, degradation kinetics, and functional microbes of HAA were largely unknown. Here, HAA bioreactors fed with acetate, glucose, sucrose, starch, methanol, and sludge alkaline fermentation liquid (SAFL) were constructed to compare the nitrogen recovery performance, kinetic analysis, sludge characteristics, and microbial community structure. Higher COD and NH4+-N removal efficiencies were found in bioreactors supplied with acetate, glucose, and SAFL. Kinetic analysis showed that the acetate-fed bioreactor had more efficient organic utilization for assimilation. Corynebacterium, Pseudohoeflea, and Methylophaga emerged as the primary assimilation bacteria for typical carbon sources of organic acids, sugars, and alcohols, whereas Halomonas, Corynebacterium, and Marinobacter dominated in SAFL. Acetate- and SAFL-supported sludge particles displayed enhanced internal and external oxygen mass transfer, along with heightened sedimentation performance and deconsolidation ability. High-quality assimilative gene expression, assimilative enzyme activity, and assimilated organic nitrogen product synthesis with direct effects were observed in a reactor supplied with acetate and SAFL. The cost-effectiveness of SAFL preparation positions it as a promising candidate for practical engineering applications. This research underscored the pivotal role of different carbon contents in the nutrient recovery process of the HAA reaction, providing essential insights for optimizing wastewater treatment strategies and enhancing environmental sustainability.

Volatile fatty acids production from kitchen waste slurry using anaerobic membrane bioreactor via alkaline fermentation with high salinity: Evaluation on process performance and microbial succession

In this study, a pilot-scale anaerobic membrane bioreactor (AnMBR) was developed to continuously produce volatile fatty acids (VFAs) from kitchen waste slurry under an alkaline condition. The alkaline fermentation effectively suppressed methanogenesis, thus achieving high VFAs production of 60.3 g/L. Acetic acid, propionic acid, and butyric acid accounted for over 95.0 % of the total VFAs. The VFAs yield, productivity, and chemical oxygen demand (COD) recovery efficiency reached 0.5 g/g-CODinfluent, 6.0 kg/m3/d, and 62.8 %, respectively. Moreover, the CODVFAs/CODeffluent ratio exceeded 96.0 %, and the CODVFAs/NH3-N ratio through ammonia distillation reached up to 192.5. The microbial community was reshaped during the alkaline fermentation with increasing salinity. The membrane fouling of the AnMBR was alleviated by chemical cleaning and sludge discharge, and membrane modules displayed a sustained filtration performance. In conclusion, this study demonstrated that high-quality VFAs could be efficiently produced from kitchen waste slurry using an AnMBR process via alkaline fermentation.

고초균-젖산균의 순차적 복합 발효를 통한 복합 기능성 물질 함유 황칠나무 추출물의 생산

The production of poly-γ-glutamic acid (γ-PGA) and γ-aminobutyric acid (GABA) was optimized by serial fermentation of Dendropanax morbiferus extract (DME) using Bacillus subtilis HA and Lactobacillus plantarum KS2020. The 1st alkaline fermentation was performed on 60% DME including 2% glucose and 10% monosodium ʟ-glutamate (MSG) as a precursor. The 1st fermented DME had 57 mg% tyrosine. Consequently, the 2nd lactic acid fermentation for 5 days increased the tyrosine content of 106 mg%. The mucilage containing γ-PGA showed a high content of 3.50% on the first day of alkaline fermentation and then increased to 4.10% after 2 days. The precursor (MSG) remaining in the 1st fermented DME was efficiently converted to GABA by the 2nd lactic acid fermentation in the presence of 5% skim milk, 1.5% glucose and 0.5% yeast extract, resulting in the production of 18.29 mg/mL GABA. The viable cells of lactic acid bacteria increased and indicated 9.49 log CFU/mL on the fermentation for 5 days, and the acidity of co-fermented DME indicated the highest value of 1.55%. Conclusively, the serial fermented DME has multi-functional ingredients containing γ-PGA, GABA, peptides and probiotics.

Simultaneous volatile fatty acids promotion and antibiotic resistance genes reduction in fluoranthene-induced sludge alkaline fermentation: Regulation of microbial consortia and cell functions

The impact and mechanism of fluoranthene (Flr), a typical polycyclic aromatic hydrocarbon highly detected in sludge, on alkaline fermentation for volatile fatty acids (VFAs) recovery and antibiotic resistance genes (ARGs) transfer were studied. The results demonstrated that VFAs production increased from 2189 to 4272 mg COD/L with a simultaneous reduction of ARGs with Flr. The hydrolytic enzymes and genes related to glucose and amino acid metabolism were provoked. Also, Flr benefited for the enrichment of hydrolytic-acidifying consortia (i.e., Parabacteroides and Alkalibaculum) while reduced VFAs consumers (i.e., Rubrivivax) and ARGs potential hosts (i.e., Rubrivivax and Pseudomonas). Metagenomic analysis indicated that the genes related to cell wall synthesis, biofilm formation and substrate transporters to maintain high VFAs-producer activities were upregulated. Moreover, cell functions of efflux pump and Type IV secretion system were suppressed to inhibit ARGs proliferation. This study provided intrinsic mechanisms of Flr-induced VFAs promotion and ARGs reduction during alkaline fermentation.

From "processing" and "fermentation" to oxidative metabolism

The theory of the four humors or humorism (Hippocrates of Kos) viewed disease as an imbalance of the humors. Galen of Pergamon further developed the theory by describing digestion as a sequence of chemical reduction processes that convert into the various humours. Theophrastus von Hohenheim attempted to overcome humorism in the 16th century and establish medicine on a natural-philosophical-alchemical basis. The era of empirical-experimental chemically oriented medicine began with "iatrochemistry" in the 17th century. Franciscus Sylvius' concept of disease is based on an imbalance of acidic and alkaline fermentation. It was Lazarro Spallanzani who understood the digestive processes in the stomach as a chemical dissolution of food. The discovery of oxygen and the process of oxidation by Lavoisier laid the foundation for our understanding the physiology of metabolism.

Effect of mixing intensity on volatile fatty acids production in sludge alkaline fermentation: Insights from dissolved organic matter characteristics and functional microorganisms

Alkaline fermentation for volatile fatty acids (VFAs) production has shown potential as a viable approach to treat sewage sludge. The hydrolysis and acidogenesis of sludge are greatly influenced by mixing. However, the effects of mixing intensity on VFAs production in sludge alkaline fermentation (SAF) remain poorly understood. This study investigated the impacts of mixing intensity (30, 90 and 150 rpm continuous mixing, and 150 rpm intermittent mixing) on VFAs production, dissolved organic matter (DOM) characteristics, phospholipid fatty acid profiles and microbial population distribution in SAF. Results showed that 150 rpm continuous and intermittent mixing enhanced the hydrolysis of sludge, while 150 rpm intermittent mixing resulted in the highest VFAs production (3886 ± 266.1 mg COD/L). Analysis of fluorescent and molecular characteristics of DOM revealed that 150 rpm intermittent mixing facilitated the conversion of released DOM, especially proteins-like substances, into VFAs. The abundance of unsaturated and branched fatty acids of microbes increased under 150 rpm intermittent mixing, which could aid in DOM degradation and VFAs production. Firmicutes and Tissierella were enriched at 150 rpm intermittent mixing, which favored the maximum VFAs yield. Moreover, Firmicutes were found to be the key functional microorganisms influencing the yield of VFAs during SAF. This study provides an understanding about the mixing intensity effects on VFAs production during SAF, which could be helpful to improve the yield of VFAs.

Co-electron donors driven medium-chain fatty acids production: Roles of electron donors, reaction kinetics and metabolic pathways

Energy conversion of waste activated sludge alkaline fermentation liquor (WASAFL) to medium-chain fatty acids (MCFAs) is promising for sludge treatment and carbon recovery. However, the single electron donor (ED) fermentation for MCFAs production has irreparable defects. To resolve the respective shortcomings of single electron donor (ED) and improve the MCFAs production efficiency from WASAFL, a novel biotechnical process utilizing ethanol and lactate as co-EDs within different combination ratios were investigated. The results verified that MCFAs production was highest with ethanol to lactate ratio of 1:3 (6988.54 ± 208.18 mg COD/L), being 1.46 and 1.87 times of that with ethanol and lactate as single ED. The kinetic analysis results confirmed that ethanol to lactate ratio of 1:3 resulted in the highest MCFAs yield and formation rate. The microbial taxa results uncovered that the relative abundance of Sphaerochaeta and Haloimpatiens showed positive correlation with MCFAs production. The metabolic pathway analysis indicated that the ethanol oxidization, lactate oxidization, acrylate pathway, reverse β oxidization and fatty acid biosynthesis pathway might take place in the WASAFL fermentation system, contributing to the WASAFL-to-MCFAs conversion.

BIOCHEMICAL AND MICROBIOLOGICAL CHARACTERIZATION OF TRADITIONAL ROMANIAN FERMENTED DRINKS - SOCATA AND BORȘ - A REVIEW

Fermented beverages are products that involve biochemical changes during the microaerophilic processes under the action of microorganisms and their secreted enzymes. Food fermentations include four main processes: lactic fermentation, alcoholic fermentation, acetic fermentation (which is an aerobic process) and alkaline fermentation. In this paper we aim to review the studies carried out on two Romanian traditional non-dairy fermented beverages which have not benefited of the attention they deserve, such as elderflower (Sambucus nigra) fermented drink (socata) and sour liquid soup seasoning (borș). These drinks are derived from a sweetened infusion of elder flowers (socata) and wheat bran (borș) that are fermented by consortia of microorganisms. Socata was shown to be fermented by consortia of yeast and lactic acid bacteria (LAB). Borș is produced by fermentation with heterofermentative LAB. These traditional fermented beverages are characterized as a source of probiotics. Previous research has demonstrated that both are a rich source of bioactive/antioxidant flavonoids and phenolic acids, minerals and vitamins. Several techniques are used for the determination of the bioactive compounds and antioxidant activity, such as the determination of individual phenolic compounds using HPLC, determination of total phenolic content using Folin- Ciocalteu reagent, determination of ABTS and DPPH radical cation scavenging activity, determination of ferric reducing antioxidant power (FRAP) assay.

Environmental factors contributing to the convergence of bacterial community structure during indigo reduction.

Indigo is solubilized through the reducing action of the microbiota that occurs during alkaline fermentation of composted leaves of Polygonum tinctorium L. (sukumo). However, the environmental effects on the microbiota during this treatment, as well as the mechanisms underlying the microbial succession toward stable state remain unknown. In this study, physicochemical analyses and Illumina metagenomic sequencing was used to determine the impact pretreatment conditions on the subsequent initiation of bacterial community transition and their convergence, dyeing capacity and the environmental factors critical for indigo reducing state during aging of sukumo. The initial pretreatment conditions analyzed included 60°C tap water (heat treatment: batch 1), 25°C tap water (control; batch 2), 25°C wood ash extract (high pH; batch 3) and hot wood ash extract (heat and high pH; batch 4), coupled with successive addition of wheat bran from days 5 to 194. High pH had larger impact than heat treatment on the microbiota, producing more rapid transitional changes from days 1 to 2. Although the initial bacterial community composition and dyeing intensity differed during days 2-5, the microbiota appropriately converged to facilitate indigo reduction from day 7 in all the batches, with Alkaliphilus oremalandii, Amphibacillus, Alkalicella caledoniensis, Atopostipes suicloalis and Tissierellaceae core taxa contributing to the improvement of when the dyeing intensity. This convergence is attributed to the continuous maintenance of high pH (day 1 ~) and low redox potential (day 2~), along with the introduction of wheat bran at day 5 (day 5~). PICRUSt2 predictive function profiling revealed the enrichment of phosphotransferease system (PTS) and starch and sucrose metabolism subpathways key toward indigo reduction. Seven NAD(P)-dependent oxidoreductases KEGG orthologs correlating to the dyeing intensity was also identified, with Alkalihalobacillus macyae, Alkalicella caledoniensis, and Atopostipes suicloalis contributing significantly toward the initiation of indigo reduction in batch 3. During the ripening period, the staining intensity was maintained by continuous addition of wheat bran and the successive emergence of indigo-reducing bacteria that also contributed to material circulation in the system. The above results provide insight into the interaction of microbial system and environmental factors in sukumo fermentation.

Impact of pH, temperature, and hydraulic residence time on the acidogenic fermentation of fruit and vegetable waste and microbial community analysis

AbstractBACKGROUNDThe carboxylic acids produced through acidogenic fermentation of fruit and vegetable waste present wide application and high added value. By performing batch experiments, the influence of pH and temperature on the acidogenic fermentation performance was investigated, and the effects of hydraulic retention time (HRT) on performance and microbial community in semi‐continuous fermentation were also studied.RESULTSA maximum product yield of 0.66 ± 0.01 g g−1 VSfed (volatile solids of feed substrate) was found at mesophilic temperature and pH 9.0; acetic acid, propionic acid, and butyric acid comprised 59%, 20%, and 21% of the product, respectively. During semi‐continuous fermentation, a maximum product yield of 0.69 ± 0.03 g g−1 VSfed was found at pH 9.0 and an HRT of 5 days. Lactic acid and acetic acid were regarded as the main products, with respective percentages of 85% and 12%. Reducing the HRT to 3 days increased the daily production from 11.33 ± 0.46 to 15.89 ± 0.67 g d−1. Microbial community analysis revealed that Lactobacillus was predominant in the semi‐continuous alkaline fermentation system.CONCLUSIONAlkaline fermentation was more favorable for obtaining higher product yield both in batch and semi‐continuous fermentation. Within semi‐continuous alkaline fermentation, the maximum yield was observed at an HRT of 5 days, but a higher daily production was found at an HRT of 3 days. Additionally, reducing the HRT did not change the dominant bacteria but could change the composition of the products. This work provides a theoretical basis and guidance for enhancing product yield and optimizing formation of product. © 2022 Society of Chemical Industry (SCI).

A novel strategy and mechanism for high-quality volatile fatty acids production from primary sludge: Peroxymonosulfate pretreatment combined with alkaline fermentation

To obtain high-quality VFAs production from primary sludge, a novel strategy that combined peroxymonosulfate (PMS) pretreatment and alkaline fermentation (i.e., PMS & pH9) was proposed in the study. The results showed that PMS & pH9 was efficient in sludge solubilization and hydrolysis, resulting in a maximal VFAs yield of 401.2 mg COD/g VSS, which was 7.3-, 2.1-, and 8.8-fold higher than the sole PMS, sole pH9, and control, respectively. Acetate comprised 87.6% of VFAs in this integration system. Mechanism investigations revealed that sulfate and free radicals produced by PMS play roles in improving VFAs yield under alkaline conditions. Besides, sulfate also aided in C3∼C5 VFAs converting to acetate under alkaline conditions depending on the increase of incomplete-oxidative sulfate-reducing bacteria (iso-SRB) (i.e., Desulfobulbus and Desulfobotulus). Moreover, the relative abundances of acid-forming characteristic genera (i.e., Proteiniborus, Proteinilcasticum, and Acetoanaerobium) were higher in PMS & pH9.

Effective mitigation of ammonia in sewage-sludge-derived fermentation liquid using flow-electrode capacitive deionization

Due to the high toxicity of ammonia to organisms and its contribution to eutrophication in surface water, the risk of emission of ammonia and other nitrogenous ions to the environment and ecosystems has aroused wide concerns. Therefore, the discharge criterion on nitrogen in effluent from conventional wastewater treatment plants (WWTP) is very stringent. Furthermore, during the conventional denitrification processes, the relatively costly external carbon source is usually required. Nowadays production of volatile fatty acids (VFAs) from sewage sludge by alkaline anaerobic fermentation has regarded as an attractive carbon source. However, usually ammonia is quite abundant in the fermentation liquid and thus effective mitigation of ammonia in the fermentation liquid is also a significant step for its further utilization. In the present study, the flow electrode capacitive deionization (FCDI) was applied to remove ammonia in the fermentation liquid of sewage sludge. Firstly, response surface method (RSM) was employed to optimize parameters and then the performance of the FCDI in ammonia removal were examined. Results showed that optimal flow rates, carbon content and ammonia concentration were 8.0 mL min−1, 4.0 wt% and 110 mg N·L−1 and the ammonia removal efficiency (ARE) reached 42.7%, while treating the alkaline fermentation liquid. Seemingly the presence of Na+ and polypeptides in the liquid with their average RE of 53.3% and 11.1% substantially compromised ammonia removal probably due to the competition of adsorption sites. This present study serves as a proven concept for the feasibility of the application of the FCDI system in ammonia separation from the VFAs, which could realize economic and ecological benefits.

Alkaline fermentation of refinery waste activated sludge mediated by refinery spent caustic for volatile fatty acids production

Volatile fatty acids (VFA), produced from waste activated sludge (WAS), provide unique opportunities for resource recovery in wastewater treatment plants. This study investigates the potential of refinery spent caustic (RSC) on VFA production during refinery WAS (RWAS) alkaline fermentation. The highest VFA yield was 196.3 mg/g-VS at a sludge retention time of 6 days. Amplicon sequencing revealed the enrichment of Soehngenia (20.21%), Bacilli (11.86%), and Brassicibacter (4.17%), which was associated with improved activities of protease (626%) and α-glucosidase (715%). Function prediction analysis confirmed that acetyl-CoA production and fatty acid biosynthesis were enhanced, while fatty acid degradation was inhibited. Accordingly, hydrolysis, acidogenesis, and acetogenesis were improved by 6.87%, 10.67%, and 28.50%, respectively; whereas methanogenesis was inhibited by 28.87%. The sulfate and free ammonia in RSC likely contributed to increased acetic acid production. This study showcases that RWAS alkaline fermentation mediated by RSC for VFA production is the practicable approach.

Evaluation of pH regulation in carbohydrate-type municipal waste anaerobic co-fermentation: Roles of pH at acidic, neutral and alkaline conditions

This study investigated and evaluated the roles of acidic (pH 4.0), neutral (pH 7.0) and alkaline (pH 10.0) in anaerobic co-fermentation of sewage sludge and carbohydrate-type municipal waste. CO2, CH4 and H2 are produced in acidic, neutral and alkaline fermentation, respectively. The neutral co-fermentation contained the vast number of aqueous metabolites as total of 22.12 g/L, with the advantage of over 50 % biodegradable components in extracellular polymeric substance and over 80 % hydrolysis rate. Acidic and alkaline pH facilitated ammonia release, with the max concentration of 0.46 g/L and 0.44 g/L, respectively. Microbial analysis indicated that pH is the key parameter to impact microbial activity and drive microbial community transition. The high abundance of Lactobacillus, Bifidobacterium and Clostridium was associated with harvest of ethanol, lactic acid and acetate in acidic, neutral and alkaline fermentation. Meanwhile, the floc feature showed better dewaterability (zeta potential −8.48 mV) and poor nutrient convey (distribution spread index 1.03) in acidic fermentation. In summary, acidic and alkaline fermentation were prioritised for targeted spectrum. Neutral fermentation was prioritised for high production. This study presented an upgraded understanding of the pH role in fermentation performance, microbial structure and sludge behaviour, which benefits the development of fermentation processing unit.

A redox-based strategy to enhance propionic and butyric acid production during anaerobic fermentation

This study investigated the selective production of volatile fatty acids (VFAs) during anaerobic mixed‐culture fermentation. The experiment used chicken manure (CM) as a potential substrate to produce high added‐value propionic acid and butyric acid under an alkaline environment. The conversion of CM into selective VFAs depends highly on operational conditions such as pH and redox balance. Therefore, the current experiment is designed to employ amino acid addition and develop a redox balance control method to control the final VFA profile. This study showed that 0.2–5.0 % valine and threonine addition successfully enhanced propionic acid and butyric acid production during alkaline fermentation and hence decreased the proportion of acetic acid from 83 % to approximately 47 %. The oxidation–reduction potential (ORP) and redox cofactor ratio (NADH/NAD+) were measured to support the selective VFA production mechanism. The results obtained in this study bring extra value to the valorization of CM within the circular economy concept for selective value-added VFA production.

Kinetic study of some flavor and bioactive compounds during fermentation of Parkia biglobosa

Seeds of Parkia biglobosa, also called African locust bean seeds (ALBSs), are used to produce a condiment by subjecting them to cooking, alkaline fermentation, and drying. The objective of this work was to monitor the evolution of the composition of ALBS during spontaneous fermentation. Results showed that the seeds at initial time contained mainly proteins (45%) and lipids (36%). During fermentation, the conversion of this initial composition took place to produce ammonium, free amino acids, and short-chain fatty acids (SCFAs) that accounted for 2%, 10%, and 1.5% dry basis, respectively, which explains the typical flavor of fermented ALBS. This release was also concomitant with biogenic amine production. Along with ammonium and SCFA release, pyrazines were the major volatile organic compounds. Composition modulation was well represented by a Verhulst equation in which the dynamic could be modified by the initial composition of the seed, the pre-cooking step, and the fermentation conditions (temperature and aeration). Practical applications For nutritional and sustainability reasons, re-integration of vegetable in general and legumes, in particular in our diet, is a current trend. However, only dish that are appealing to consumers are concretely adopted. Fermentation of legumes is interesting in more than one way. It does not involve heat, so thermolabile molecules can be preserved and the financial and energetic costs are low. Biological interesting molecules are produced from the metabolism of microorganisms, and among them, volatile organic compounds that contribute to enhance the flavor of legume dishes. Soumbala is a meal and/or condiment obtained from the fermentation of African locust bean (Parkia biglobosa) seeds (ALBSs), a legume widely spread in west Africa. The final typical sensory properties are known to be due to the alkaline fermentation step by Bacillus species. This paper presents the kinetics of release of various compounds during spontaneous fermentation that may impact the sensory and nutritional properties of the final product. More precisely, the dynamic of the production of free amino acids, free fatty acids, volatile compounds, and biogenic amines are presented and discussed to give insights into the succession of important reactions to control the sensory and nutritional qualities of fermented ALBS (FALBS). This paper shows that further research are necessary to better understand and control the quality of not only FALBS but also similar protein-rich legumes to modulate the quality of the final products.

Re-hydrolysis characteristics of alkaline fermentation liquid from waste activated sludge: Feasibility as a carbon source for nitrogen removal

To overcome the issue of substandard nitrogen and phosphorus discharge, resulting from the low carbon/nitrogen (C/N) ratio of municipal wastewater, immobilized filler was used to re-hydrolyze the alkaline fermentation liquid of waste activate sludge (WAS) as a nitrogen removing carbon source. The complex organic matter was further hydrolyzed and its denitrification efficiency as a carbon source for nitrogen removal was improved. Volatile fatty acids increased from 1605 ± 5 mg/L to 2546 ± 37 mg/L after re-hydrolysis of mixed-alkali sludge fermentation liquid, and complex organic matter, such as fulvic acids, humic acids, class I aromatic proteins, and soluble microbial products were hydrolyzed into small-molecule organics. When the re-hydrolysis fermentation liquid (RH-SFL) was used as the carbon source for nitrogen removal, the nitrogen removal effect was close to sodium acetate and the nitrogen removal rate (NRR) was up to 98.5 ± 0.5%. According to the NOX--N removal curve, the reaction rate of RH-SFL was significantly higher than before re-hydrolysis (nRH-SFL) (0.486 > 0.38). This technology can significantly improve the effective organic quality in the alkaline fermentation liquid of WAS, which can be more easily utilized by denitrifying bacteria. This provides a feasible and effective solution for nitrogen removal in municipal wastewater with insufficient carbon.

Recent Progress in Electronic Noses for Fermented Foods and Beverages Applications

Fermented foods and beverages have become a part of daily diets in several societies around the world. Emitted volatile organic compounds play an important role in the determination of the chemical composition and other information of fermented foods and beverages. Electronic nose (E-nose) technologies enable non-destructive measurement and fast analysis, have low operating costs and simplicity, and have been employed for this purpose over the past decades. In this work, a comprehensive review of the recent progress in E-noses is presented according to the end products of the main fermentation types, including alcohol fermentation, lactic acid fermentation, acetic acid fermentation and alkaline fermentation. The benefits, research directions, limitations and challenges of current E-nose systems are investigated and highlighted for fermented foods and beverage applications.

Rapidly achieving partial denitrification from nitrate wastewater in a alkaline fermentation system with primary sludge as inoculated sludge and fermentable substrate

In order to promote practical engineering application of anaerobic ammonium oxidation(anammox) process, reduction of primary sludge(PS) in wastewater treatment plants(WWTPs) and removal of nitrate contaminant, a single-stage simultaneous alkaline fermentation coupled with partial denitrification(SAFPD) system was established successfully in this study. Nitrite production was rapidly achieved from nitrate wastewater with PS as inoculated sludge and fermentable substrate under anaerobic and anoxic operating conditions. During the stable operation period, the primary sludge reduction(PSR) and productivity of organic matters were 27.9% and 483.8mgCOD/gVSS, with nitrate removal of 90.7%, NO3– to NO2– transformation ratio(NTR) of 80.0%. After 125 days of acclimation, the relative abundance of Thauera, Dechloromonas and Candidatus_Competibacter increased from 0.17%, 0.02% and 0.05% to 11.58%, 4.28% and 5.6% respectively. Above results showed that this SAFPD system not only realized the reduction of PS and nitrate removal, but also laid a solid foundation for anammox process with its high nitrite production.