Removal Efficiencies Of TP Research Articles

Iron [Fe(0)]-carbon micro-electrolysis enhances simultaneous nitrogen and phosphorus removal in vertical flow constructed wetlands for advanced treatment of reclaimed water

Constructed wetland is an effective method to remove N and P from reclaimed water, but the treatment effect is restricted by low temperature in winter. In this study, a vertical flow constructed wetland based on Iron [Fe (0)]-carbon micro-electrolysis (IC-ME) (IC-CW) was developed for advanced treatment of reclaimed water. The performance of IC-ME carrier on simultaneous N and P removal under different operational conditions and cold temperature was investigated. Studies have shown that when the HRT is 48 h and the influent C/N ratio is 2.5, the removal efficiencies of TN and TP reach to 88.6% and 92.2%. When operating under low temperature conditions (water temperature at 9.6–18.6 °C and ambient temperature at −14.2 to 8.4 °C), the effluent quality is slightly lower than that at normal temperature, with the TN and TP removal efficiencies of 72.7% and 89.2%. The functional microorganisms in IC-CW were analyzed and the results showed that aerobic bacteria and anaerobic bacteria coexist in the IC-CW, and there are both aerobic nitrification and anaerobic denitrification processes in the IC-CW. In addition, there are more functional denitrifying characteristic microorganisms such as Denitratiosoma attached on the IC-ME carrier (2.18%) than that on the ceramsite (0.92%). The developed IC-CW presented significant potential in the practical application for advanced treatment of reclaimed water.

Characteristic of KMnO4-modified corn straw biochar and its application in constructed wetland to treat city tail water.

Biochar prepared from straw as constructed wetland (CW) substrate reduces straw pollution and simultaneously promotes the wastewater treatment efficiency of CW. In order to further analyze the pollutant removal mechanism of KMnO4-modified biochar substrate, the KMnO4-modified biochar was characterized. The experiment on city tail water treatment by CW with biochar was analyzed. The research showed that the surface property improvement on KMnO4 (0.1mol/L)-modified biochar was the most obvious. The biochar modified by 0.1mol/L KMnO4 increased the SSA and the number of oxygen functional groups and alcohol hydroxyl. KMnO4-modified biochar improved the removal efficiency of NO3--N in CW. KMnO4-modified biochar substrate with plants improved the TP removal efficiency (about 45%). KMnO4 as modifier reduced the influence of biochar on electrical conductivity tracing experiment. This study will improve the utilization value of straw and the removal efficiency of CW.

Wastewater treatment performance and gaseous emissions in MFC-CWs affected by influent C/N ratios

Constructed wetlands with microbial fuel cells (MFC-CWs) are widely acknowledged to be efficient in pollutant removal, and have been reported to be beneficial in reducing specific gaseous emissions. However, as a critical parameter that directly addresses, the behavior of carbon (C) and nitrogen (N), the impact of the influent C/N ratio on the comprehensive performance of MFC-CWs remains unknown. Herein, the impact of C/N ratios (i.e., 1, 5, 10, 15) on pollutants (COD, NH4+-N, NO3–-N, NO2–-N, TN and TP) removal, multiple gaseous (CO2, CH4, N2O and NH3) emissions and electricity generation of MFC-CWs were evaluated, and the internal mechanisms were explored. Increasing the C/N ratio enhanced COD removal, and the MFC-CWs achieved superior NH4+-N, TN, and TP removal efficiencies at C/N ratios of 5 and 10. The higher C/N ratio was generally accompanied by greater CO2, CH4, and NH3 fluxes. Nevertheless, the lowest global warming potential (GWP) was observed at C/N of 5 due to the lowest N2O flux having been obtained. The functional gene analysis results showed that the decrease in N2O flux was attributed to an increase in the nosZ/(nirS + nirK) ratio, and the CH4 flux was regulated by the abundance of pomA and mcrA genes. The highest power density (152.54 mA/m3) and current intensity (649.03 mW/m3) were also observed in MFC-CWs with a C/N ratio of 5, mainly due to the increase in electrogenic bacteria (e.g., Proteobacteria and Firmicutes). Consequently, the influent C/N ratio of 5 was optimal for treating wastewater and generating electricity efficiently, and also attenuating the corresponding GWP in MFC-CWs.

Improvement in water pollution control alters nutrient stoichiometry of Guanting Reservoir near Beijing, North China.

Significant improvement in wastewater treatment is the most effective way for eutrophication control, especially in semiarid regions. However, its effect on the nutrient status and stoichiometry of the receiving water body has remained poorly considered and understood at broad temporal scales. Taking Guanting Reservoir (GR) in Hebei-Beijing (P. R. China) as an example, we present a study that links a continuous monitoring dataset for GR with corresponding estimates of human-induced nutrient discharges in its watershed from the year 2006 to 2019. We find that current GR belongs to strict P limitation and the faster decrease of TP than TN concentrations and continuous increase of TN/TP mass ratios in GR are attributed to the water restoration investment-induced declining of nutrient loadings. The improved municipal wastewater treatment capacity is mainly responsible for these significant changes, due to the higher removal efficiency of TP than TN in municipal wastewater. Given the potential ecological impact on aquatic biodiversity as well as ecosystem function of changes in TN/TP ratios and higher retention rate of TP (97.4%) compared with TN (93.1%) in GR, our findings highlight that future strategy for water pollution control should not only concentrate on more nutrient reduction efficiencies but attach importance to their stoichiometric balance to reduce the potential risk of phytoplankton blooms and toxin production during the water quality recovery of lakes or reservoirs.

Modeling growth kinetics and community interactions in microalgal cultures for bioremediation of anaerobically digested swine wastewater

Uncontrolled release of swine wastewater into the environment causes the eutrophication of water bodies, as well as soil and air pollution, among other environmental and health issues. Microalgal-based wastewater treatment (MbWT) is a cost-effective alternative to traditional wastewater treatment methods that offers the opportunity to harvest valuable biomass while simultaneously removing nutrients and organic matter, thus making wastewater treatment a circular bioeconomy process. The aim of this work was to test three microalgal strains, Chlorella vulgaris, Scenedesmus acutus, and Arthrospira maxima, in mono-cultures and co-cultures using raw (undiluted, non-sterilized) anaerobically digested swine wastewater (ADSWW). An overall performance index (OPI) proposed herein showed that the treatments that included C. vulgaris were the most efficient in terms of biomass growth, along with COD and nutrient removal. The co-culture of C. vulgaris and S. acutus achieved the highest OPI of 0.68, displaying a maximum biomass concentration of 2.97 ± 0.36 g/L, as well as 89 %, 56 %, and 67 % removal efficiencies for COD, TN, and TP, respectively. Three mathematical models were used to estimate relevant growth kinetic parameters, including the specific growth rate, lag-phase duration, interspecific interaction, affinity constant, and biomass productivity. The growth curve of the C. vulgaris monoculture was adjusted using a double Gompertz model, showing a growth rate of 0.625 d−1 and a lag phase of 0.71 days in the first growth stage. The Lotka-Volterra model was used to assess interactions between both strains in the co-culture, showing a commensalistic relationship as denoted by the interspecific parameters (βcs = 1.99 ± 0.92 and βsc = −0.007 ± 0.008). Finally, the growth kinetics as a function of the three substrates (COD, TN, and TP) were adjusted to the Monod model, and the resulting parameters were used to simulate a continuous process that evidenced the requirement of P supplementation.

Optimization of operating parameters for biogas production using two-phase bench-scale anaerobic digestion of slaughterhouse wastewater: Focus on methanogenic step.

The objective of the present study was an optimization of operating parameters and the performance of the methanogenesis reactor in phased anaerobic digestion (AD) of slaughterhouse wastewater at 37.5°C. Accordingly, the feedstock of the methanogenic reactor was effluent from the hydrolytic-acidogenic reactor operating at HRT of 3-days and OLR of 1789 mg/L. The methanogenesis phase was also investigated at different hydraulic retention time (HRT) values ranging from 12 to 3days at 3-day intervals, and organic loading rates (OLR) of 149, 199, 298, and 596mg of COD/L. The methanogenesis reactor effluent concentrations of TN, TP, PO4-3, SO4-2, and S2-2 were ranging between 424-464, 83-117, 63-86, 130-197, and 0.98-1.02mg/L, respectively. The removal efficiencies of TN and TP were vary from 10-17% to 17-21%, respectively. The average biogas production was 125 ± 16, 150 ± 10, 185 ± 4, and 154 ± 17mL at HRT of 12, 9, 6, and 3days, respectively. Methane quality (%) and yield (mg/L of COD) were 55-67% and 0.02-0.03, respectively. Furthermore, the average stability indicator parameter values of (total volatile fatty acid (TVFA) = 520 ± 19mg/L, total alkalinity (TotA) = 1424 ± 10mg/L, TVFA:TotA. Ratio = 0.36, salinity = 1172mg/L, pH = 6.92) and performance indicator parameters removal efficiency (RE) for (chemical oxygen demand (COD) = 81%, volatile solid (VS) RE = 95%, biogas production = 185 ± 4mL, methane yield = 0.03 per mg COD consumed) were achieved at HRT of 6days and OLR of 298mg of COD/L. Low removal efficiencies of TP and TN at all HRT/OLR were observed for the methanogenic reactor signifying further treatment system.

Tolerance and recovery of aerobic granular sludge: Impact of perfluorooctanoic acid

The widespread use of perfluorooctanoic acid (PFOA) has rendered its frequent detection in wastewater. The tolerance and recovery of aerobic granular sludge (AGS) to PFOA were investigated in short-term (Phase Ⅰ) and long-term (Phase Ⅱ, operation strategy adjustment: shortening aeration time and prolonging anaerobic and anoxic time). Results showed that in Phase Ⅰ, the performance of R2 reactor (0.05 mg/L PFOA) was slightly negatively affected, while 0.5 and 2.0 mg/L PFOA in R3 and R4 reactors significantly damaged the key enzyme activities of AGS, leading to deterioration of nutrients removal. TN and TP removal efficiencies decreased correspondingly from 79.32% to 78.41% on day 0 to 74.66% and 74.14% in R2 and 68.57% and 67.80% in R3 and 56.94% and 57.47% in R4 on day 7, respectively. In Phase Ⅱ, the key enzyme activities of AGS were obviously renewed dependent on operation strategy adjustment and AGS self-regulation. The performance of AGS in R2 (continuously dosing 0.05 mg/L PFOA) and R4 (stopping dosing PFOA) recovered quite good, while the long-term adverse effects of 0.5 mg/L PFOA on AGS in R3 were still more difficult to be alleviated. In end of Phase Ⅱ (69–97days), the average TN and TP removal efficiencies correspondingly reached 83.31% and 82.09% in R1 (control), 80.67% and 79.62% in R2, 76.38% and 74.27% in R3, and 79.01% and 78.25% in R4, respectively. Further analysis revealed that the effect of PFOA on proteins in extracellular polymeric substances (EPS) was greater than that on polysaccharides. Specifically, short-term dosage of PFOA mainly affected loosely bound EPS, while long-term dosage of PFOA affected tightly bound EPS. Although AGS is severely inhibited by short exposure to 2.0 mg/L PFOA (in R4), after the operation strategy adjustment, EPS content decreased, nutrient and oxygen transport channels of AGS were re-established, which contributed to the recovery of AGS.

A comprehensive study of biological phosphorus removal systems from economic and environmental perspectives based on the optimization approach

Different biological phosphorus removal systems (BPRSs) are evaluated from economic and environmental perspectives by employing the Taguchi optimization approach for the first time. The BPRSs were simulated and compared in terms of total phosphorus removal efficiency (TP RE) using GPS-X software. Step Bio-P, the most efficient system, was selected for the subsequent environmental and cost analysis. At the optimum condition, the Step Bio-P with a 96.98% TP RE stood at the first rank, followed by the Johannesburg (83.17%)> University of Cape Town (UCT) (79.63%)> anaerobic/anoxic/oxic (A 2 O) (79.31%)> anoxic/oxic (AO) (78.89%)> Bardenpho (70.48%). Marine and freshwater ecotoxicity (59.57%) and freshwater eutrophication (11.84%) received the highest environmental impacts. Construction (77.66%) and amortization (7.3%) caused the maximum cost contributions. The sensitivity analysis revealed that chemical oxygen demand (COD) (17.48%) and TP (9.98%) imposed the maximum effects on the environmental categories. These results can be used as a guideline for wastewater reclamation. • Step Bio-P showed the highest TP removal efficiency (96.98%) • The Taguchi optimization confirmed the role of initial TP on the RE (30.08%) • Marine and freshwater ecotoxicity (59.57%) showed the highest environmental impacts. • Construction possessed the maximum cost contributions (77.66%). • The sensitivity analysis showed the effect of COD and TP on the environmental impacts.

Treatment of swine wastewater using multi-soil-layer based constructed wetland: Substrates assessment and efficiency improvement

Dispersed discharge of decentralized swine wastewater without effective treatment has become a widespread problem in rural areas, threatening the regional water environment. To address the above issues, performance of the multi-soil-layer based constructed wetland (MSL-CW) in treating swine wastewater during long-term operation was investigated, with the substrates type and their layout in the MSL-CW being compared. Results showed that zeolite performed best in NH+4-N removal, while iron filling had the highest removal capacities for TP, followed by cinder. Removal efficiencies of COD, NH+4-N, and TP could be substantially facilitated in the MSL-CW without reducing agents (rMSL-CW) compared to that in control CW, normal MSL-CW, and MSL-CW with the mixed substrates. The relatively excellent treatment performance of rMSL-CW indicated that changes in environmental conditions (such as ORP and aeration) induced by removing reducing agents might be the reason for the differences in treatment performances among CWs. Furthermore, the treatment efficiency of rMSL-CW could be further improved by increasing the ORP, in which applying the aeration and removing the compact surface soil were found to be conducive to COD removal and NH+4-N removal, respectively. This study suggested the promising potential for long-term operation and full-scale application of rMSL-CW for swine wastewater treatment.

A novel two-stage process for the effective treatment of swine wastewater using Chlorella sorokiniana AK-1 based algal-bacterial consortium under semi-continuous operation

This study aimed at developing an eco-friendly and effective treatment for swine wastewater (SWW) using a designer microalgae-bacteria consortium. A functional algal bacterial consortium was developed with SWW-derived bacteria and Chlorella sorokiniana AK-1. Light intensity (300 µmol/m2/s) and inoculum size (0.15 and 0.2 g/L for microalgae and bacteria) were optimized. Semi-batch operation treating 50 % SWW resulted in a COD, BOD, TN, and TP removal efficiency of 81.1 ± 0.9 %, 97.0 ± 0.7 %, 90.6 ± 1.6 % and 91.3 ± 1.1 %, respectively. A novel two-stage process with an initial bacterial start-up stage followed by microalgal inoculation was applied for attaining stable organic carbon removal, in addition to satisfactory TN and TP removal. Full strength SWW was treated with this strategy with COD, BOD, TN, and TP removal efficiencies of 72.1 %, 94.9 %, 88 %, and 94.6 %, respectively. The biomass consisted of 36 % carbohydrates, indicating a potential feedstock for biochar production. In addition, the effluent met the standards for effluent discharge in Taiwan.

Integration of MFC reduces CH4, N2O and NH3 emissions in batch-fed wetland systems

The combination of microbial fuel cells (MFCs) with constructed wetlands (CWs) for enhancing water purification efficiency and generating bioelectricity has attracted extensive attention. However, the other benefits of MFC-CWs are seldom reported, especially the potential for controlling gaseous emissions. In this study, we have quantitatively compared the pollutant removal efficiency and the emission of multiple gases between MFC-CWs and batch-fed wetland systems (BF CWs). MFC-CWs exhibited significantly (p < 0.01) higher COD, NH4+-N, TN, and TP removal efficiencies and significantly (p < 0.01) lower global warming potential (GWP) than BF CWs. The integration of MFC decreased GWP by 23.88% due to the reduction of CH4 and N2O fluxes, whereas the CO2 fluxes were slightly promoted. The quantitative PCR results indicate that the reduced N2O fluxes in MFC-CWs were driven by the reduced transcription of the nosZ gene and enhanced the ratio of nosZ/(nirS + nirK); the reduced CH4 fluxes were related to pomA and mcrA. Additionally, the NH3 fluxes were reduced by 52.20% in MFC-CWs compared to BF CWs. The integration of MFC promoted the diversity of microbial community, especially Anaerolineaceae, Saprospiraceae and Clostridiacea. This study highlights a further benefit of MFC-CWs and provides a new strategy for simultaneously removing pollutants and abating multiple gas emissions in BF CWs.

Mechanism of Fe-C micro-electrolysis substrate to improve the performance of CW-MFC with different factors: Insights of microbes and metabolic function.

Constructed wetland-microbial fuel cell (CW-MFC) is a novel technology for wastewater treatment with electrical generation. This work proposed a Fe-C micro-electrolysis substrate (Fe-C) with biomass modified ceramsite to enhance pollutants removal and electricity generation. The key influencing factors were revealed, and the COD, NH4+-N, and TP removal efficiency was respectively increased by 10.2, 8.1 and 8.78% with 76% higher power output at optimal conditions (e.g. OLR 52.5g/(m2.d), HRT 48h, and aeration rate 800mL/min). Fe-C based substrates improved the microenvironments in CW-MFC, including dissolved oxygen (DO) and oxidation-reduction potential (ORP) lowering and electron transfer facilitation. These contributed to the enrichment of critical microorganisms and metabolic activities. The abundance of functional bacteria (i.e. Geobacter, Thauera and Dechloromonas) were evidently increased. Additionally, the energy metabolism and other functional genes encoding cytochrome c (ccoN), nitrite reductase (nirD) and phosphate transporter (pstA) were all stimulated.

Effects of feeding methods on ecological soil wastewater infiltration systems for sewage treatment

Intermittent feeding method and continuous feeding method were adopted in two experimental form ecological soil wastewater infiltration systems (ESWISs), respectively. The results showed that COD, NH4 + and TN removal efficiencies were enhanced from 81.8%, 70.5% and 45.8% in continuous feeding ESWIS to 90.0%, 88.5% and 72.7% in intermittent feeding ESWIS. The same TP removal efficiency was achieved in two feeding mehtods. Matrix oxidation reduction potential (ORP) was enhanced through the intermittent feeding ESWIS, especially above 60 cm depth of the matrix, which encouraged nitrification. The metabolic activity and reproduction of microbes were improved by intermittent feeding method, such as actinomyces, bacteria, nitrifying bacteria, fungus. Meanwhile, denitrifying bacteria and nitrate reductase (NR), nitrite reductase (NIR) activities were also increased. PCR-DGGE analysis confirmed that intermittent feeding method improved bacterial diversity. These results suggest that intermittent feeding method is viable to heighten the performance of ESWISs in sewage treatment.

A novel MABR process based on HN-AD bacteria-chlorella symbiotic system: Effects of COD/TN ratios on performance, community structure, functional bacteria and key genes

Microorganisms in heterotrophic nitrification-aerobic denitrification (HN-AD) mixed bacteria-Chlorella symbiotic system are difficult to be fixed and easily lost in continuous flow process. Meanwhile, excessive aeration in traditional aeration method might result in CO2 stripping. In this study, the membrane-aerated biofilm reactor (MABR) was employed to achieve efficient nitrogen and phosphorus removal with different COD/TN ratios based on HN-AD mixed bacteria-Chlorella symbiotic system. The results showed that compared with the HN-AD bacteria system, the symbiotic system reduced 33.3 % carbon demand and 43.6 % CO2 emission. The removal efficiency of TN and TP increased by 14.9 % and 51.2 %, respectively. The SEM, EPS and EEM analysis indicated that, the biofilm mass and intensity reached its best conditions at the optimal COD/TN ratio of 8. 16S rRNA high-throughput sequencing and functional gene prediction indicated that Chlorella increased the abundance of HN-AD functional bacteria (Acinetobacter, Pseudomonas and Paracoccus played a key role) and the expression of functional gene (Nas). This paper provides new insights for the application of the novel HN-AD mixed bacteria-Chlorella symbiotic system in MABR, which will be beneficial for future research.

French Type Constructed Wetlands for Sewage Treatment: Experiences from the Swings Prototype in India

This study aimed to investigate the performance of the French Type Constructed Wetlands (FTCW) at a pilot scale level in real field conditions for sewage treatment in India. The pilot plant consisted of hybrid wetlands in two stages, vertical and horizontal sub-surface flow types. The first stage comprised three compartments, vegetated with three different native plants (phragmites australis, canna indica, and sagittaria), operated in parallel, and sequentially loaded. Each VSSF bed of 12.25m2 was fed with raw sewage directly for 3.5 days followed by twice the time resting period. The second stage consisted of one bed of an area of 45m2, planted with canna indica. The filter media used in stage 1 was a dual type (gravel and coarse sand) in three layers. The first stage was designed for the loadings of 33.75gBOD/m2d and 14.1 gNH4-N/m2d with the flexibility to operate at a variable hydraulic loading rate (HLR). Two years of monitoring data after the steady-state condition show variable performances at different hydraulic loading rates. Removal efficiencies of COD, BOD5, TSS, TN, and TP of the hybrid system at HLR of 0.4m/day were 87.1%, 87.3%, 84.6%, 67.93%, and 69.32% respectively. Doubling the HLR, the efficiency of the system decreased marginally for the same parameters. Out of the three vegetation, the bed planted with phragmites has shown the highest removal efficiency. The study has demonstrated that FTCW can be a suitable proposition as one of the potential methods for sewage treatment in India and similar regions.

Response of microbial interactions in activated sludge to chlortetracycline

Chlortetracycline (CTC) has attracted increasing attention due to its potential environmental risks. However, its effects on bacterial communities and microbial interactions in activated sludge systems remain unclear. To verify these issues, a lab-scale sequencing batch reactor (SBR) exposed to different concentrations of CTC (0, 0.05, 0.5, 1 mg/L) was carried out for 106 days. The results showed that the removal efficiencies of COD, TN, and TP were negatively affected, and the system functions could gradually recover at low CTC concentrations (≤0.05 mg/L), but high CTC concentrations (≥0.5 mg/L) caused irreversible damage. CTC significantly altered bacterial diversity and the overall bacterial community structure, and stimulated the emergence of many taxa with antibiotic resistance. Molecular ecological network analysis showed that low concentrations of CTC increased network complexity and enhanced microbial interactions, while high concentrations of CTC had the opposite effect. Sub-networks analysis of dominant phyla (Bacteriodota, Proteobacteria, and Actionobacteriota) and dominant genera (Propioniciclava, a genus from the family Pleomorphomonadaceae and WCHB1-32) also showed the same pattern. In addition, keystone species identified by Z-P analysis had low relative abundance, but they were important in maintaining the stable performance of the system. In summary, low concentrations of CTC enhanced the complexity and stability of the activated sludge system. While high CTC concentrations destabilized the stability of the overall network and then caused effluent water quality deterioration. This study provides insights into our understanding of response in the bacteria community and their network interactions under tetracycline antibiotics in activated sludge system.

Efficiencies and mechanism of enhanced coagulation pre-treatment on domestic sewage with PAC-HCA compound.

Poly dimethyl diallyl propyl ammonium chloride (HCA) and poly aluminum chloride (PAC) were used to prepare complex coagulants for the enhanced coagulation (EC) pretreatment of domestic sewage. The influences of hydraulic conditions, the dosage ratio of PAC-HCA complex coagulants, initial pH value, and dosage on the removal efficiency of SS, COD, and TP in domestic sewage were investigated. The fractal dimension and Zeta potential were used to verify and characterize the experimental results. The results showed that the optimum coagulant conditions were as follows: G1 = 200.0-265.0 s-1, T1 = 1.5 min, G2 = 40.0 s-1, T2 = 5 min, PAC: HCA = 25:1, dosage = 15 mL/L, pH = 8. At the mentioned point, the removal rates of SS, COD, and TP are 98.74%, 44.63%, and 89.85%, respectively. In addition, through comparative tests, PAC-HCA compound coagulants show better treatment efficiency than PAC and HCA used alone. When the HCA dosage was 15 mg/L, Zeta potential and flocs fractal dimension was 2.29 mv and 0.9844, respectively. This indicates that PAC-HCA has a good treatment effect on domestic sewage, and the mechanism of enhanced coagulation to remove nutrients is mainly electrical neutralization.

Fabrication of immobilized algal-bacterial beads and its application in synthetic mariculture tail water treatment

With the rapid expansion of the maricultural scale, the treatment of mariculture tail water (MTW) has become a focus of marine environmental protection. Meanwhile, as a cost-effective wastewater treatment technology, immobilized algal-bacterial beads (IABB) has received wide attention. The nutrients removal of wastewater by IABB is limited by the stability and strength of the beads during the treatment process. In this study, the fabrication of IABB composing Chlorella vulgaris and activated sludge with different concentration of SA (1.5%, 2.5% and 3.5% w/v) and Ca2+ (2%, 3.5% and 5% w/v) and their application in the treatment of synthetic MTW was primarily investigated. The SA concentration has significant impact on the characteristics of IABB. Specifically, 2.5% of SA resulted in the formation of IABB with the best homogeneity, chemical and mechanical stability. Ca2+ concentration affect the nutrient removal efficiency during MTW treatment. The IABB fabricated under the conditions of 2.5% SA and 2% Ca2+ showed the highest removal efficiency of NH3-N, TP and COD within the 48 h of experiment, i.e. 66.7 ± 3.2, 81.0 ± 2.8 and 90.7 ± 1.9%, respectively. Therefore, the application of IABB offers promising prospects for MTW treatment and marine environmental safety.

Bioelectrochemical processes and cellulosic carbon source enhance the autotrophic and heterotrophic denitrification of low C/N ratio wastewater in tidal flow constructed wetland - Microbial fuel cells

To solve the problem of poor nitrogen and phosphorus removal efficiency of low C/N ratio wastewater, a siphon constructed wetland - microbial fuel cell (CW-MFC) reactor was constructed. And the influence of electrochemical process on autotrophic denitrification and nitrogen removal was studied. The effects of agricultural waste as cellulose carbon source on heterotrophic denitrification and electricity generation were also investigated. In addition, related electrochemical processes and microbial mechanisms were studied. The results indicated that MFC enhanced autotrophic denitrification. The addition of cellulose carbon source could significantly promote the heterotrophic denitrification process ( P < 0.05). In 137 days, the reactor with carbon source added to both cathode and anode (CS CW-MFC) had the best removal effect on COD , NH 4 + -N and TN, with removal rates of 98.38%, 79.31% and 84.43%, respectively. The removal efficiency of TP reached 89.92%. Adding carbon sources facilitated biological electricity production. The maximum voltage was 450 mV, and the maximum power density was 113.95 mW m −3 . However, methane emissions increased slightly with the addition of carbon sources. Compared with previous studies, tidal flow via siphon aeration could significantly improve TN removal efficiency. Bioelectrochemical processes had significant impact on the autotrophic denitrifying bacteria, the relative abundance of Bacteroidota and Proteobacteria was the highest. This study suggests that the addition of cellulose carbon source and the operation of tidal flow CW-MFC can enhance treatment of low C/N ratio wastewater. This technology not only enables agricultural waste to be recycled, but also improves the efficiency of sewage treatment and energy recovery. • Bioelectrochemistry affected autotrophic denitrification and nitrogen removal. • Cellulose carbon source was beneficial to heterotrophic denitrification. • The addition of cellulose carbon source increased the system electricity generation. • The tidal flow in CW-MFC can enhance the treatment of low C/N ratio wastewater. • Autotrophic/heterotrophic denitrification and bioelectroactive bacteria coexisted.

Fast granulation of flocculent activated sludge by mycelium pellet and wastewater biological treatment performance

To investigate the universality of mycelium pellet (MP) assisted flocculent activated sludge (FAS) granulation, four different filamentous microbes (Aspergillus niger, Aspergillus fumigatus, Phanerochaete Chrysosporium and Streptomyces albicans) were used for bio-flocculation assisted activated sludge granulation, and the physicochemical properties and biological activity of aerobic granular sludge (AGS) with MP as skeleton were monitored. The results showed that inoculation of MP for an assisted flocculation strategy was better than filamentous spores. Spherical and rod-shaped microbes of FAS alternately adhered to different areas of the MP to form granular sludge with dense structure. Under the optimized conditions, the FAS biomass aggregated on four MPs reached 1.24–1.89 g/g, and the respiratory activity of corresponding MP-based AGS (MP-AGS) were 36.52–56.95 mgO2/gVSS of specific oxygen consumption rate. Compared to FAS, MP-AGS present better sedimentation performance (45–55 m/h of settling rate) and higher biological enzyme activity related to organic matter degradation and nitrogen conversion (49.82–60.37 mgTF/(gVSS∙h) of dehydrogenase, 0.26–0.42 mgNO2−-N/(min∙mg protein) of nitrate reductase). TN and TP removal efficiencies of MP-AGS were 9.96 %–19.59 % higher than those of FAS under high influent loads. This study confirmed the feasibility of mycelium pellet assisted flocculent activated sludge granulation using different microbes.