Primary Sludge Fermentation Research Articles

Effects of aging of polyethylene microplastics and polystyrene nanoplastics on antibiotic resistance gene transfer during primary sludge fermentation

The increasing presence of nano and microplastics (NPs/MPs) in wastewater treatment plants and their inevitable accumulation in the sludge has raised serious concerns in recent years. This study investigated the effects of pristine and aged polyethylene microplastics (PEMPs), polystyrene nanoplastics (PsNPs), and their mixtures on the primary sludge fermentation process. Pristine MPs/NPs (150 μg/L and 2 g/L for PsNPs and PEMPs, respectively) underwent two weeks of weathering in the presence of humic and alginic acids. The results from a batch fermentation experiment (15 days, pH 10) revealed that the exposure to aged PEMPs/PsNPs experienced greater VFA production than pristine samples. Notably, the aged PEMPs/PsNPs mixture showed a 23.12% increase in VFA production over the pristine mixture. The relative abundance and total concentration of antibiotic resistance genes (ARGs) increased in all PEMPs/PsNPs batches compared to the control, with the most significant rise in total ARGs observed in the aged PEMPs sample. Aged PEMPs exhibited a 26.22-fold increase in tetA genes, while aged mix samples showed a 19.68-fold increase in tetM genes compared to their pristine counterparts. Both pristine and aged PEMPs/PsNPs, particularly the aged PEMPs adversely affected the microbial communities at the genus level and altered the microbial structure. Microbial richness and diversity were enhanced in samples exposed to pristine PEMPs/PsNPs and aged PsNPs but decreased in aged PEMPs and in the aged mixture group, suggesting a negative impact of aged polyethylene microplastics on microbial communities. Correlation analysis suggested that phyla Planctomycetes, Proteobacteria, and TM7 are potential hosts of ARGs. These findings manifest the substantial effects of aged nano/microplastics compared to their pristine forms, emphasizing the complex interplay between various forms of PEMPs/PsNPs and microbial dynamics in sludge fermentation processes.

Impact of polystyrene nanoplastics on primary sludge fermentation under acidic and alkaline conditions: Significance of antibiotic resistance genes

As a part of industrial or commercial discharge, the influx of nanoplastics (NPs) to the wastewater treatment plants is inevitable. Consequently, it has become a must to understand the effects of these NPs on different unit processes. This study aimed to investigate the impact of three different concentrations of polystyrene nanoplastics (PsNPs) on the fermentation of primary sludge (PrS), implemented in batch anaerobic bioreactors, at pH 5 and 10, considering the pH-dependent nature of the fermentation process. The results showed that PsNPs stimulated hydrogen gas production at a lower dose (50 μg/L), while a significant gas suppression was denoted at higher concentrations (150 μg/L, 250 μg/L). In both acidic and alkaline conditions, propionic and acetic acid predominated, respectively, followed by n-butyric acid. Under both acidic and alkaline conditions, exposure to PsNPs boosted the propagation of various antibiotic resistance genes (ARGs), including tetracycline, macrolide, β-lactam and sulfonamide resistance genes, and integrons. Notably, under alkaline condition, the abundance of sul2 gene in the 250 μg PsNPs/L batch exhibited a 2.4-fold decrease compared to the control batch. The response of the microbial community to PsNPs exposure exhibited variations at different pH values. Bacteroidetes prevailed at both pH conditions, with their relative abundance increasing after PsNPs exposure, indicating a positive impact of PsNPs on PrS solubilization. Adverse impacts, however, were detected in Firmicutes, Chloroflexi and Actinobacteria. The observed variations in the survival rates of various microbes stipulate that they do not have the same tolerance levels under different pH conditions.

Improving carbon management through maximizing hydrolysis and fermentation at water resource recovery facilities

Wastewater treatment plants are transitioning from a sole focus on treatment objectives to integrated resource recovery and upcycling. Effective carbon management is critical for upcycling within a water resource recovery facility (WRRF) to produce energy or other usable products, which involves carbon diversion at primary treatment and waste activated sludge (WAS) from biological treatment processes. Many WRRFs are also driven to meet stringent effluent nutrient discharge targets while minimizing energy usage and chemical addition. Nutrient removal systems still rely on biodegradable organic carbon to support denitrification and enhanced biological phosphorus removal (EBPR). Biological nutrient removal not only requires sufficient organic substrate, but also the right type of bioavailable carbon for optimal utilization. The main objective of this pilot fermentation testing was to evaluate the most effective utilization of the range of organic-carbon rich feedstocks within a WRRF. Preliminary results suggest that a 50–50 blend of primary sludge (PS) and return activated sludge (RAS) fermentation leads to highest volatile fatty acid (VFA) yield. PS fermentation resulted in the minimum nutrients release per unit of volatile suspended solids (VSS), which makes it a best suited for biological nutrients removal WRRFs with stringent nitrogen (N) and phosphorus (P) limits. The volatile fatty acids fractions produced from different combinations of RAS and PS can impact the most suitable end use for each sludge type fermentation. PS resulted into higher levels of propionate, which are ideal for selecting phosphate accumulating organisms (PAO) over glycogen-accumulating organisms (GAO). On the other hand, for denitrification, acetate is the preferred substrate, which was most abundant with RAS only fermentation. Our research outcomes will be of value to utilities aiming to integrate the stringent effluent nutrient (N and P) discharge targets with energy and resource recovery.

Low-temperature thermal hydrolysis for enhancing sludge anaerobic digestion and antibiotic resistance management: Significance of digester solids retention time

Recently, there has been a growing inclination towards utilizing primary sludge (PS) fermentation prior to anaerobic digestion (AD) in water resource recovery facilities (WRRFs), where sludge liquor containing volatile fatty acids is used for biological nutrient removal. Nevertheless, using a low-temperature thermal hydrolysis process (THP) to improve AD in WRRFs adopting PS fermentation remains an area that has received limited research attention. Here, we studied the impact of THP (90 °C, 90 min) on anaerobic co-digestion of thickened waste activated sludge (TWAS) and fermented primary sludge (FPS) under varying solids retention times (SRTs) in semi-continuous mode. The study involved two THP schemes: scheme 1, where THP was done for both TWAS and FPS, and scheme 2, where THP was applied to TWAS only. The results demonstrated that reducing SRT from 20 to 15 and 10 d leads to decreased methane yield in both schemes. However, THP significantly enhances methane production, showing improvements of up to 37.9 % (scheme 1) and 31.2 % (scheme 2) under a 15-d SRT. Furthermore, while decreasing SRT increased the proliferation of antibiotic resistance genes (ARGs), thermal hydrolysis could effectively reduce most ARGs, indicating its potential to mitigate antibiotic resistance in the AD process. Overall, these results provide useful perceptions regarding the potential adoption of low-temperature THP in WRRFs with PS fermentation.

The dual role of potassium ferrate in promoting primary sludge hydrolysis and acidogenesis in anaerobic fermentation

Potassium ferrate (PF), a green disinfectant has been widely used in drinking water disinfection and has drawn immense attention for its application in sludge treatment. This research study has investigated the effects of PF on the hydrolysis and acidification of primary sludge (PS) to promote the short chain fatty acids (SCFAs) recovery, while achieving solid waste treatment and carbon emission reduction. The results showed that PF could effectively promote the accumulation of SCFAs, and maximum SCFAs yield of 4686.56 mg COD/L was achieved by PF assisted PS fermentation at a PF dosage of 0.4 g/g VSS, which was 2.05 times higher than the control. Substance transformation and enzyme activity analysis indicated that PF significantly promoted the release and hydrolysis of insoluble organic matters from PS through chemical oxidation and alkaline hydrolysis. Furthermore, high doses of PF could also inhibit the growth of methanogens and alter the dominant fermentation flora responsible for SCFAs production. Under the influence of high-dose PF, the foremost acidogenic bacteria were shifted into Trichococcus, Enterococcus, Streptococcus and Gallicola, which might be selectively enriched under the stress of residual Fe (Ⅲ) in the system. The PS fermentation liquid produced after PF pretreatment exhibited a higher C/N ratio and lower phosphorus concentration, which enhanced its suitability as carbon sources for denitrification in WWTPs. This study offered an environmentally friendly method for recovering SCFAs from PS and provided a viable approach to addressing the issue of carbon source shortage in wastewater treatment processes.

Batch Simultaneous Saccharification and Fermentation of Primary Sludge at Very High Solid Concentrations for Bioethanol Production

A sustainable industrial future involves the exploitation of renewable resources to obtain a wide diversity of products and energy and the decrease of waste generation. Primary sludge (PS) from pulp and paper mills is a lignocellulosic residue mainly consisting of cellulose and hemicelluloses that can be converted to bioethanol. In the present work, bioethanol was produced from untreated PS by simultaneous saccharification and fermentation (SSF). Studies were carried out on initial solid concentration, yeast inoculum percentage, cellulolytic enzyme dosage, and co-application of two enzyme complexes (cellulolytic NS 22192 and xylanolytic Cellic® HTec2, Bagsværd, Denmark). Increasing solid content up to 22% improved ethanol concentration (59.1 g L−1), productivity (1.97 g L−1 h−1), and yield (86.3%); however, at the maximum solid concentration (28%), both yield and productivity decreased. At the highest solid concentration, a decrease of 33% in the cellulolytic enzyme dosage was observed (compared to reference enzyme loadings). The co-application of the two enzyme complexes had a positive effect on PS conversion efficiency. When a preliminary scale-up strategy was implemented from 50 mL to 2.5 L at 22% solids concentration, similar results were obtained despite the initial mixing difficulties of the heterogeneous system.

Primary filtration of municipal wastewater with sludge fermentation – Impacts on biological nutrient removal

Primary filtration is a compact pre-treatment process for municipal wastewater, which can lead to high removal of total suspended solids (TSS) if polymer is added prior to filtration. Extensive carbon removal with rotating belt filter (RBF) can be combined with filter primary sludge fermentation at ambient temperature, in order to produce volatile fatty acids (VFAs) as carbon source for biological nutrient removal (BNR). This process was implemented at large pilot-scale and operated for more than a year. The results showed that the RBF efficiently removed particles >10 μm, and that the TSS removal had a strong linear correlation to the influent TSS concentration. Fermentation of the sludge at ambient temperature and five days retention time and addition of the fermentate to the wastewater could nearly double the VFA concentration in the wastewater by adding 31 ± 9 mg VFA-COD/L. Meanwhile, an increase of 2 mg/L of ammonium nitrogen, and 0.7 mg /L of phosphate phosphorus would be added to the wastewater with the fermentate. Adding the fermented sludge to the wastewater stream and removing the particles with RBF makes it possible to utilize nearly all the produced VFAs for BNR, and the feasibility of this configuration was shown at pilot-scale. According to simulations of subsequent BNR, the pre-treatment would lead to lower effluent total nitrogen concentrations. Alternatively, the required BNR volume could be reduced by 11–18 %. The estimated total biogas production was similar for pre-treatment with primary settler and RBF with fermentation. RBF without fermentation gave the most favourable energy balance, but did not reach the same low effluent value for total nitrogen as RBF with fermentation.

Seasonal variations in acidogenic fermentation of filter primary sludge

Primary treatment of municipal wastewater by rotating belt filtration followed by hydrolysis and acidogenic fermentation of the filter primary sludge (FPS) at ambient temperature was studied at pilot-scale during one year. The seasonal variations of volatile fatty acids (VFAs), nutrient release and soluble COD production as well as microbial community assembly were assessed, leading to novel findings for fermentation at ambient temperature. The reproducibility of VFA production performance was first established by operating the two fermentation reactors under the same conditions, showing similar results regarding VFA production and microbial community structure. One year of operation at 5 d retention time (RT) and 16–29 °C resulted in an average VFA yield of 180±35 mg COD/g VSin and soluble COD yield of 242±40 mg COD/g VSin. The VFA formation was temperature-dependent, with ϴ=1.033±0.005 (r=r20·Θ(T−20∘C)). The seasonal variations of the acetic and propionic acid productions were pronounced, whereas the productions of VFAs with longer chains were more stable regardless of temperature. The community structure of the reactor microbiomes was also clearly affected by season and temperature and linked with the production spectrum of VFAs. The ammonium and phosphate releases were stable during the year, leading to a decrease in ratios of soluble COD to NH4+-N and PO43−-P during winter. The soluble COD yield was 11% and 27% higher at 5 d RT compared to 3 and 2 d RT respectively, but the corresponding volumetric productivities were lower. The dissimilarities between microbiomes in influent FPS and fermenters were significant even at a short RT of 2 d, and increased with longer RT of 3 and 5 d, primarily caused by selection of bacteria within Bacteroidota in the fermentation reactors.

Enhanced short chain fatty acids production from anaerobic fermentation of primary sludge using free ammonia pretreatment

This study is the first to report a new free ammonia (FA) pretreatment technique to recover short-chain fatty acids (SCFAs) from primary sludge (PS). The results showed FA pretreatment (240 mg N/L) largely enhanced the SCFAs production from PS to 355.8 mg chemical oxygen demand (COD)/g VSS, which was about 4.5-fold that of control (i.e., 80 mg COD/g VSS). Mechanism investigations showed that FA pretreatment greatly accelerated the PS solubilization and destroyed the integrity of EPS, and the easily biodegradable substrates in the fermentation broth increased significantly, providing microorganisms with more organics to convert into SCFAs. Further analyses displayed that FA greatly inhibited the methane production during fermentation, resulting in further accumulation of SCFAs. Given that the NH4+-N released during the fermentation can be converted into FA in situ, this could facilitate the transition of wastewater treatment plants operation from linear to circular mode.

Application of Primary Sludge Fermentation for the Production of Carbon Source for Full-Scale Biological Nutrients Removal

Application of Primary Sludge Fermentation for the Production of Carbon Source for Full-Scale Biological Nutrients Removal

Intermittent Microaeration Technology to Enhance the Carbon Source Release of Particulate Organic Matter in Domestic Sewage

Domestic sewage treatment plants often have insufficient carbon sources in the influent water. To solve this problem, the commonly used technical means include an additional carbon source, primary sludge fermentation, and excess sludge fermentation, but these methods are uneconomical, unsustainable, and not applicable to small-scale wastewater treatment plants. Intermittent microaeration technology has the advantages of low energy-consumption, ease of application, and low cost, and can effectively promote anaerobic digestion of municipal sludge; however little research has been reported on its use to enhance the carbon sources release of particulate organic matter (POM) from domestic wastewater. Therefore, the effect of intermittent microaeration on the carbon source release of POM was evaluated in this study, with POM as the control test. The results showed that the release concentration of soluble chemical oxygen demand (SCOD) was the highest on day 4 under microaerobic conditions, and the concentrations of SCOD, NH4+-N, and PO43−-P in the liquid phase were 1153, 137.1, and 13 mg/L, respectively. Compared with the control group, the SCOD concentration increased by 34.2%, and the NH4+-N and PO43−-P concentrations decreased by 18.65% and 17.09%, respectively. Intermittent microaeration can effectively promote the growth of Paludibacter, Actinomyces, and Trichococcus hydrolytic fermentation functional bacteria. Their relative abundances increased by 282.83%, 21.77%, and 23.47%, respectively, compared with the control group. It can simultaneously inhibit the growth of acetate-type methanogenic archaea, Methanosaeta and Methanosarcina, with a decrease in relative abundances of 16.81% and 6.63%, respectively. The aforementioned data show that intermittent microaeration can not only promote the hydrolysis of POM, but can also reduce the loss of acetic acid carbon source, which is a cost-effective technical way to enhance the release of a carbon source of particulate organic matter in domestic sewage.

A new mechanical cutting pretreatment approach towards the improvement of primary sludge fermentation and anaerobic digestion

Pretreatment technologies for improving the anaerobic digestion of waste activated sludge have been studied extensively; however, studies on the improvement of pretreatment technology for primary sludge (PS) fermentation and anaerobic digestion are scarce. In this study, a novel mechanical cutting pretreatment (MCP) method was proposed to enhance the performance of PS fermentation and anaerobic digestion. PS was disintegrated by MCP, the average particle size of PS reduced from 45.7 µm to 7.0 µm, and soluble COD (SCOD) increased by 1206 mg/L with pretreatment for 8 min. The hydrolysis and acidification of PS was promoted significantly by MCP. Compared with the control group, the production of SCOD and volatile fatty acids (VFAs) in the pretreatment group during sludge fermentation increased by 167% and 115.3%, respectively. The performance of PS anaerobic digestion was remarkably improved by MCP. The maximum cumulative biogas production in the pretreatment group was 3153 mL, which was 6.33 times that in the control group (498.5 mL). Sludge disintegration by mechanical pretreatment resulted in the enrichment of bacteria, especially Firmicutes, in the sludge fermentation system, and the quantity of bacteria in the pretreatment group was 1.95 times that in the control group. However, MCP had little effect on archaea in the anaerobic digestion of PS, and the methanogens in the control and pretreatment reactors were 1.493 × 109 and 1.519 × 109 copies/g, respectively.

Enhancement of denitrification efficiency using municipal and industrial waste fermentation liquids as external carbon sources

The addition of external carbon source for nitrogen removal from wastewater is an essential step in wastewater treatment. In this study, various external carbon sources from the fermentation of primary sludge (PS), thickened waste activated sludge (TWAS), food waste (FW), bakery processing & kitchen waste (BP + KW), fat, oil, & grease (FOG), and whey powder (WP) were successfully employed for wastewater denitrification. Methanol and acetate were also used as controls due to their common use as external carbon sources for wastewater denitrification. The denitrification performance and kinetics such as the specific denitrification rate (SDNR), denitrification potential (PDN), and the biomass yield were studied at a constant TVFA as COD/N ratio of 5 for all substrates. Complete denitrification was achieved with a NO3−-N removal efficiency of 98–99%, and no NO2− accumulation was observed at the end of the experiments for all substrates. The results revealed that the liquid fermentation filtrates exhibited higher SDNRs than methanol and acetate. This indicates the high organic matter utilization efficiency and better denitrification ability of fermentation filtrates over conventional carbon sources. WP exhibited the highest SDNR of 17.6 mg NOx − N/g VSS/h, which is approximately four times that of methanol (4.6 mg NOx − N/g VSS/h). The other carbon sources had SDNRs two to three times higher than that of methanol. However, the fermentation filtrates exhibited higher biomass yields of 0.26–0.37 mg VSS/mg COD compared to methanol of 0.21 mg VSS/mg COD, which could lead to higher sludge handling costs. Moreover, methanol exhibited higher PDN of 0.25 g N/g COD compared to all the fermentation filtrates.

Response of VFAs and microbial interspecific interaction to primary sludge fermentation temperature

It's not clear how fermentation affects the succession and interspecific interaction of functional microorganism in primary sludge anaerobic fermentation system. So as to explore the decisive role of temperature on microorganisms to reveal the mechanism, four fermentation experiments groups (25, 35, 45, and 55 °C) were designed. Results indicated the promotion in proportion of acetic and iso-valeric acid with temperature increasing. High-throughput sequencing reflected that the dominant microbial groups in all samples were Proteobacteria, Firmicutes, Bacteroidetes, Synergetes, Spirochaetae, and then key microbial interspecific interaction changed significantly due to the adjustment of microbial temperature. In addition, amino acid metabolism was the lowest at 35 °C, but carbohydrate metabolism was the highest. The metabolic abundances of amino acids at different temperatures were the highest, but the differences among kind of amino acids were significant. This study could reveal the effect of temperature on VFAs production in terms of microbial interspecific interaction and lay a theoretical foundation for sludge fermentation.

Low-temperature thermal hydrolysis for anaerobic digestion facility in wastewater treatment plant with primary sludge fermentation

Primary sludge (PS) fermentation prior to anaerobic digestion (AD) is becoming more common in wastewater treatment plants (WWTPs) for the production and utilization of volatile fatty acids-rich sludge liquor in biological nutrient removal processes. However, the thermal hydrolysis process (THP) for enhancing AD of sludge in WWTPs with PS fermentation has rarely been investigated. This study examined low-temperature THP (50–90°C, 30–90 min) for enhancing co-digestion of fermented primary sludge (FPS) and thickened waste activated sludge (TWAS). The experiments were conducted under two schemes: scheme-1 (THP of TWAS + FPS) and scheme-2 (THP of TWAS only). Scheme-2 was more effective in solubilizing COD (up to 20.4% increase in SCOD) and various macromolecular compounds (e.g., proteins and carbohydrates). In contrast, scheme-1 was more efficient in VSS solubilization (up to 26.12%). Scheme-1 also resulted in a greater enhancement in methane production over the control (scheme-1: 56.28% at 90°C, 90 min vs. scheme-2: 43.4% at 90°C, 60 min). Thus, these results suggested that low-temperature THP of TWAS alone (scheme-2) would result in solubilization of refractory macromolecular compounds, leading to a relatively lower positive impact on methane yields than scheme-1. The preliminary economic assessment considering THP operating cost, enhancement in energy recovery, and saving in biosolids handling costs indicated that THP at 90°C (90 min) under scheme-1 could provide the highest net saving of $79.55/dry tonne solids compared to the control (AD without THP). These results will provide technical guidance in adopting THP in WWTPs with PS fermentation.

A New Mechanical Cutting Pretreatment Approach Towards the Improvement of Primary Sludge Fermentation and Anaerobic Digestion

A New Mechanical Cutting Pretreatment Approach Towards the Improvement of Primary Sludge Fermentation and Anaerobic Digestion

Optimization of thermal hydrolysis process for enhancing anaerobic digestion in a wastewater treatment plant with existing primary sludge fermentation

Many wastewater treatment plants (WWTPs) adopted primary sludge fermentation to produce sludge liquor for the biological denitrification process. The fermented primary sludge (FPS) is usually co-digested with thickened waste activated sludge (TWAS) in the anaerobic digestion (AD) process. To date, there has been limited information on how the sludge thermal hydrolysis process (THP) could be retrofitted for enhancing AD in WWTPs with the existing primary sludge fermentation process. This study assessed two THP retrofitting schemes, (FPS + TWAS and TWAS alone) combining different exposure times (15, 30, and 60 min) and temperatures (140, 160, and 180 °C). The results suggested that temperature had more impact on sludge solubilization than exposure times. Notably, 180 °C was the most effective for sludge solubilization under both schemes. However, a higher degree of solubilization did not necessarily lead to higher methane yields. The THP of FPS + TWAS attained considerably higher methane yield than the pretreatment of TWAS alone.

Elucidating salinity adaptation and shock loading on denitrification performance: Focusing on microbial community shift and carbon source evaluation

To understand the denitrification efficiency and microbial community shift with increasing salinity in salinity adaptation and shock loading process, nitrate (NO3–-N), nitrite (NO2–-N) and chemical oxygen demand (COD) removal efficiencies were monitored feeding acetate and primary sludge fermentation liquid. During adaptation process, salinity had little effect on NO3–-N removal efficiency (>99.0%) with acetate-fed, while for fermentation liquid-fed, it decreased to around 97% at high salinity (>2.5%). Effluent NO2–-N was lower than 0.1 mg/L, though obvious fluctuation of NO2–-N was observed with fermentation liquid-fed when salinity change. During shock loading process, denitrification process all had slight decrease when the salinity abruptly increased to 5.0%. Traditional denitrifier of Thauera was the dominant genus, and a specialized microbial community of Azoarcus in salinity adaptation and Paracoccus in shock loading for denitrification showed high salinity tolerant. Meanwhile, microbial diversity was enriched with fermentation liquid-fed at high salinity condition.

Enzymatic pre-treatment for enhancement of primary sludge fermentation

This research showed the interrelated impact of cellulase enzyme, temperature, and SRT on enhancement of primary and rotating belt filter (PS, RBF) sludges fermentation. SRTs of 1, 2, and 4-days were tested at 25 °C and 35 °C. Enzymatic enhancement was examined using three different doses of enzyme (i.e. 0.5%, 1%, and 1.5% of the total solids in the feed). The results showed a positive impact of enzyme dose as well as temperature and SRT on VFA and soluble COD production. For the RBF sludge, enzyme addition enhanced the VFA yield of fermentation at room temperature (25 °C) from 52–103 mgCOD/g VS to 93–188 mgCOD/g VS, as compared with increase from 78–192 to 87-202 mgCOD/gVS in PS. Intensification of the fermentation process, particularly for the cellulose-rich RBF sludge, by enzyme addition confirms process viability as an alternative to the extraneous carbon sources for biological nutrient removal in wastewater treatment plants.

Sludge alkaline fermentation enhanced anaerobic- multistage anaerobic/oxic (A-MAO) process to treat low C/N municipal wastewater: Nutrients removal and microbial metabolic characteristics

This study aimed to present a strategy that utilizing semi-continuous flow primary sludge fermentation liquor as carbon source for anaerobic- multistage anaerobic/oxic (A-MAO) process to treat low chemical oxygen demand (COD) and total nitrogen (TN) (C/N) ratio municipal wastewater. The results showed that adding fermentation liquor resulted in average TN and total phosphorus (TP) concentration in effluent decreased from 33 and 2.80 mg L−1 to 9.2 and 0.23 mg L−1, respectively, which met wastewater discharge standard. High-throughput sequencing results indicated that bacterial richness increased and diversity decreased with fermentation liquor adding, and the dominant genera varied from Methylophilaceae and Methylotenera to unclassified_f_Rhodocyclaceae, noran k_f__env.OPS_17, and Azospira. Meanwhile, the abundance of metabolism and organismal systems in A-MAO process rose from 48.42% and 0.74% to 49.52% and 0.78%. The improvement of nitrogen and phosphorus removal with fermentation adding was based on the increment of enzyme coding genes in nitrogen and phosphorus pathway.