Matter In Wastewater Research Articles

Application of Nano Bubble Aeration Technology in Domestic Wastewater Treatment: Optimization of Gas Flow and Reaction Time

Nano bubble aeration is an emerging technology with significant potential in wastewater treatment, particularly for removing suspended solids and organic matter. This study investigates the application of nano bubble aeration in the treatment of domestic wastewater, focusing on the reduction of chemical oxygen demand (COD) and total suspended solids (TSS). Nano bubbles, with diameters ranging from tens of nanometers to a few micrometers, exhibit slower rising velocities and prolonged stability in water due to their negatively charged surfaces. Various nano bubble air flow rates were tested over 90-minute intervals to determine the optimal treatment conditions. The results indicate that a flow rate of 2 liters per minute achieves the highest treatment efficiency, reducing COD by 84.73% and TSS by 77.51%. Increasing the flow rate beyond this level showed minimal improvement, demonstrating that 2 liters per minute is the optimal flow rate for efficient wastewater treatment using nano bubble aeration. This research highlights the advantages of nano bubble technology in enhancing the treatment efficiency of suspended solids and organic matter in wastewater.

Effects of artemia and tilapia density on the ability to treat organic matter in wastewater from white leg shrimps (Litopenaeus vannamei) farming

White leg shrimp (Litopenaeus vannamei) farming effluent contains pollutants that include high levels of total suspended solid (TSS), chemical oxygen demand (COD) and growth promoting substances. This study investigated the possibility of using artemia to filter suspended solids and Tilapia (Oreochromis niloticus) to consume organic waste of shrimp, uneaten food at the bottom of wastewater tanks of industrial shrimp farming. Both artemia and Tilapia had the ability to rapidly reduce organic matter content in wastewater of industrial shrimp farming in tanks. This contributed to reducing total suspended solid in wastewater when discharged into the environment. The biochemical oxygen demand (BOD₅), chemical oxygen demand (COD), total suspended solid (TSS) met effluent standards in Circular No. 44/2010/TT-BNNPTNT and QCVN 11-MT:2015/BTNMT in all of the investigated plots. In the surface wastewater of wastewater tanks, the remaining TSS, BOD₅, and COD contents were the lowest at 6.2 ± 1.1 mg/L, 3.9 ± 0.5 mg/L, and 8.6 ± 1.4 mg/L, respectively, in the stocking density of 300 artemia individuals/L. In the bottom wastewater, the remaining TSS, BOD₅, and COD contents were the lowest at 21.4 ± 5.1 mg/L, 8.5 ± 1.5 mg/L, and 11.6 ± 3.6 mg/L, respectively, in the stocking density of 16 Tilapia individuals/m3.

Sewer transport conditions and their role in the decay of endogenous SARS-CoV-2 and pepper mild mottle virus from source to collection

This study presents a comprehensive analysis of the decay patterns of endogenous SARS-CoV-2 and Pepper mild mottle virus (PMMoV) within wastewaters spiked with stool from infected patients expressing COVID-19 symptoms, and hence explores the decay of endogenous SARS-CoV-2 and PMMoV targets in wastewaters from source to collection of the sample. Stool samples from infected patients were used as endogenous viral material to more accurately mirror real-world decay processes compared to more traditionally used lab-propagated spike-ins. As such, this study includes data on early decay stages of endogenous viral targets in wastewaters that are typically overlooked when performing decay studies on wastewaters harvested from wastewater treatment plants that contain already-degraded endogenous material. The two distinct sewer transport conditions of dynamic suspended sewer transport and bed and near-bed sewer transport were simulated in this study at temperatures of 4 °C, 12 °C and 20 °C to elucidate decay under these two dominant transport conditions within wastewater infrastructure. The dynamic suspended sewer transport was simulated over 35 h, representing typical flow conditions, whereas bed and near-bed transport extended to 60 days to reflect the prolonged settling of solids in sewer systems during reduced flow periods. In dynamic suspended sewer transport, no decay was observed for SARS-CoV-2, PMMoV, or total RNA over the 35-h period, and temperature ranging from 4 °C to 20 °C had no noticeable effect. Conversely, experiments simulating bed and near-bed transport conditions revealed significant decreases in SARS-CoV-2 and total RNA concentrations by day 2, and PMMoV concentrations by day 3. Only PMMoV exhibited a clear trend of increasing decay constant with higher temperatures, suggesting that while temperature influences decay dynamics, its impact may be less significant than previously assumed, particularly for endogenous RNA that is bound to dissolved organic matter in wastewater. First order decay models were inadequate for accurately fitting decay curves of SARS-CoV-2, PMMoV, and total RNA in bed and near-bed transport conditions. F-tests confirmed the superior fit of the two-phase decay model compared to first order decay models across temperatures of 4 °C–20 °C. Finally, and most importantly, total RNA normalization emerged as an appropriate approach for correcting the time decay of SARS-CoV-2 exposed to bed and near-bed transport conditions. These findings highlight the importance of considering decay from the point of entry in the sewers, sewer transport conditions, and normalization strategies when assessing and modelling the impact of viral decay rates in wastewater systems. This study also emphasizes the need for ongoing research into the diverse and multifaceted factors that influence these decay rates, which is crucial for accurate public health monitoring and response strategies.

Synergistic adsorption&photo-Fenton degradation of meloxicam and tetracycline by hollow nanoflower-like S-scheme FeWO4/ZnIn2S4 heterojunction: Mechanism, toxicity assessment, and potential applications

The rational construction of materials with dual rapid adsorption&photo-Fenton oxidative degradation functions holds great significance in the field of removing difficult-to-degrade organics. A late-model S-scheme heterojunction photocatalyst FeWO4/ZnIn2S4 was prepared by solvothermal method in this paper. The FeWO4 nanoparticles were distributed on the surface of the hollow nanoflowers assembled by ZnIn2S4, forming heterojunction structures. Representative drug residues, tetracycline (TC) and meloxicam (MLX), were selected as targets to systematically explore the removal properties of FeWO4/ZnIn2S4. This photocatalyst exhibited suitable adsorption ability, excellent photocatalytic performance, and good photo-Fenton ability for both targets. The removal efficiency of tetracycline and meloxicam by 20-FW/ZIS reached 92.9 % and 98.7 %, respectively, through a combination of adsorption&photo-Fenton degradation, with these remarkable properties being maintained after four consecutive cycles. Based on the detection of active species and the analysis of degradation intermediates, an adsorption&photo-Fenton removal mechanism and possible degradation pathway were proposed. Escherichia coli (E. coli) inhibition experiments, combined with Toxicity Estimation Software Tool (T.E.S.T.) simulated toxicity analysis, showed that the toxicity of TC and MLX decreased significantly following the photocatalytic reaction. In brief, the newly developed multifunctional photocatalyst 20-FW/ZIS, as prepared in this paper, demonstrates great potential for effectively treating organic matter in wastewater, with promising applications for practical use.

Study the Utilization of Biochar Derived from Sugarcane Waste to Enhance the Biogas Efficiency During the Anaerobic Digestion Process for Treating Pig Farm Wastewater

This experiment aims to study the use of biochar (Biochar, BC) from sugarcane trash through the pyrolysis process at different temperatures of 300, 400, 500, 600 and 700°C. Then add BC to the Anaerobic Digestion (AD) system of wastewater from pig farms, then analyze the characteristics of wastewater and the amount of biogas obtained before and after treatment and to study the characteristics of decomposition, the generation of biogas (Biogas) to the reduction of organic matter in wastewater (COD). From this experiment, it can be concluded that all 6 systems are producing biogas, such as: the normal system and the system with BC filling at different burning temperatures: 300, 400, 500, 600 and 700℃ in the amount of 0.4g into the system. .64, 46.13, 51.90 and 65.98% respectively. From the experiments of all systems, it is observed that the system filled with BC at a temperature of 700℃ is able to produce biogas the best because the high heating temperature will cause the electrons of the charcoal to break easily and cause more holes to be a place for microbes to grow well. A comparison of the conventional system and adding biochar with the same amount but different temperature into the sewage treatment system without using air can be concluded that the conventional system is the generation of biogas is still low efficiency and the system of adding BC at the temperature of 300, 400, 500, 600℃ in the same amount. Notice that the generation of biogas is higher in order and the filling of BC at a temperature of 700℃ is able to produce biogas higher than other systems.

Wastewater-based surveillance for SARS-CoV-2 in Alberta

ObjectiveAlberta's largest research universities collaborated to expand COVID-19 wastewater monitoring throughout the province to regularly provide evidence of SARS-CoV-2 burden in municipalities representing 3.2 million people. ApproachSampling was conducted at 26 wastewater treatment plants and facilities across the province. The project quantified SARS-CoV-2 genomic material in wastewater to reveal population-level trends of COVID-19 cases. This inclusive and comprehensive strategy captures everyone who contributes to wastewater, including those not clinically diagnosed. Researchers collected wastewater samples in municipalities three times a week. Additional sentinel monitoring was undertaken in neighbourhoods, hospitals, long-term care facilities, worksites, shelters, and schools. Results were shared on the public COVID Data Tracker website (https://covid-tracker.chi-csm.ca/). Data was additionally linked with hospital outcomes, workforce absenteeism and outbreak information. ResultsWastewater-based surveillance (WBS) for SARS-CoV-2 genomic RNA associates very strongly with clinically diagnosed cases and health resource utilization, providing a ≥6-day leading indicator. WBS can effectively be performed across a range of geographic scales (from cities to individual facilities), ensuring actionable data that is relevant to end-users. We have published how outbreaks across a range of high-risk facilities can be monitored and predicted with WBS and can also be used to model COVID-19-associated workforce absenteeism. Emails and website interactions suggested widespread citizen engagement using data for evidence-based decisions. ConclusionWBS is a valuable tool for identifying potential outbreaks and tailoring response measures at the policy level and by individual citizens. We've created customizable real-time data-sharing tools catering to both the public (enhanced data transparency) and government (actionable insights).

Changes in chemical characteristics and toxicity of fluoxetine and humic acid during chlorination

The coexistence of emerging pollutants and dissolved organic matter in wastewater complicates the transformation and generation of disinfection byproducts (DBPs) during chlorination treatment, which is essential for effective water quality evaluation and chlorination optimization. This study used fluoxetine (FLX) and humic acid (HA) as representative substances to analyze changes in their chemical characteristics and zebrafish embryonic developmental toxicity under different chlorination conditions. The analysis of the fluorescence characteristics and Fourier transform ion cyclotron resonance mass spectrometry indicated that chlorination treatment increased the aromatic compound content of the HA solution. FLX addition further increased the presence of aromatic ring structures and oxidized molecules, resulting in the formation of numerous Cl-DBPs with highly unsaturated and phenolic structures. Moreover, different responses in zebrafish embryo development and behavior were found with FLX, HA, and FLX + HA exposures. Cardiotoxicity was linked to changes in the concentration of cTn-I protein and expression of various genes. Prolonged chlorination conditions showed higher toxicities. Correlation analysis found a weak relation between chemical indicators and toxicity data, indicating that both analysis methods need to be considered when analyzing the impact of the chlorination. Further, a combination of chemical analyses and toxicity tests revealed that the FLX + HA solution with chlorination conditions of 3 mg/L for 30 min had lower chemical and toxic effects in this experiment. This study provides valuable scientific insights for the safe discharge of chlorinated water containing FLX and dissolved organic matter, as well as guidance for optimizing chlorination parameters in wastewater treatment.

Ferrate (IV) synthesis using derived persulfate during treatment of oil recovery wastewater

ABSTRACT Using oil recovery wastewater as the target material, the degradation of organic matter in oilfield wastewater was studied in an anodic oxidation system using Ti/Ru-Ir oxide-coated anode and 0.7mMNa2SO4 as the electrolyte. The TOC of the wastewater was 210 mg/L at the beginning of the electrolysis in the electrolysis system, and it decreased from 210 to 93.6 mg/L after 50 min of electrolysis. Under the action of this system, sulfate was oxidized to persulfate, and the apparent concentration of persulfate was 15.02 mM, oxidation and degradation of organic matter in wastewater by the action of newly generated persulfate.. Afterwards, NaOH and Fe2(SO4)3 were added to the electrolyzed wastewater, and the TOC in the wastewater was further reduced to 25.1 mg/L due to the coagulation effect of the newly generated Fe(OH)3 precipitate. The TOC removal rate of the wastewater treated by this process reached 88.0%, which meets the discharge requirements. At the same time, the derived persulfate oxidized Fe(OH)3 to generate a green substance, which was identified as Na2FeO3 by IR, UV, and XRD analyses. Na2FeO3 served as a highly effective water-purifying agent, demonstrating superior performance when compared to FeO4 2-. The method reported in this study not only provides a strategy for waste resource recycling but also offers the potential for mass production of ferrate (IV).

The efficiency of enhanced nitrogen and phosphorus removal in a vertical flow constructed wetland using alkaline modified corn cobs as a carbon source

Adding carbon sources to constructed wetlands can improve nitrogen removal efficiency. Modifying plant biomass can solve problems such as excessive release of nitrogen, phosphorus, and organic matter in the initial stage and insufficient carbon supply in the later stage. This article utilized alkali-modified corn cob as a carbon source to construct vertical flow constructed wetlands and to study the carbon release characteristics of alkali-modified corn cob, as well as its removal effect on organic matter in wastewater. The results indicated that the solid-to-liquid ratio in the alkali modification process of corn cob was 1:10, and it was found that the best treatment method for alkali modified corn cob was to use a sodium hydroxide concentration of 2%, a treatment time of 12 h, and a temperature of 20 °C. Its surface roughness increases, which is beneficial for releasing carbon sources and promoting the growth of microbial attachment. Furthermore, the porosity also increases and. Intermittent aeration could significantly enhance the removal of NH4+-N, and TP in constructed wetlands. The average removal rates of NH4+-N and TP were 60.93% and 89.50%, respectively, and the average removal rates of COD, NO3--N and TN were 60.67%, 98.38% and 83.73%, respectively. At the same time, alkali-modified corn cobs were used as carbon sources. It can effectively remove NO3--N and promote denitrification in constructed wetlands.

Effect of long chain fatty acids on biogas production and biochemical kinetics in anaerobic bioreactors: a review

Long Chain Fatty Acids (LCFAs) are the primary intermediate byproduct of the lipid (fats, oils, and greases) degradation process, and if they accumulate in high concentrations, they can cause failure or reduce the performance of anaerobic bioreactors due to sludge flotation issues, biochemical kinetics problems for soluble substrates, inhibition of microbial activity, and inefficient biogas recovery. Understanding the biochemical kinetics of anaerobic bioreactors requires taking into account the entire process, including microbe growth, substrate degradation, and product synthesis. Biochemical kinetics of anaerobic treatment is the study of polymer biodegradation rates of insoluble organic matter in wastewater, which is the mechanism of bond breaking and bond formation in biochemical reactions. As a result, biochemical kinetics allow for the design of both desired and undesirable reaction phases. The kinetic parameters acquired are utilized to design, operate, and optimize anaerobic bioreactors for wastewater treatment on a technical scale.

Enhancing bioelectrochemical hydrogen production from industrial wastewater using Ni-foam cathodes in a microbial electrolysis cell pilot plant

Microbial electrolysis cells (MECs) have garnered significant attention as a promising solution for industrial wastewater treatment, enabling the simultaneous degradation of organic compounds and biohydrogen production. Developing efficient and cost-effective cathodes to drive the hydrogen evolution reaction is central to the success of MECs as a sustainable technology. While numerous lab-scale experiments have been conducted to investigate different cathode materials, the transition to pilot-scale applications remains limited, leaving the actual performance of these scaled-up cathodes largely unknown. In this study, nickel-foam and stainless-steel wool cathodes were employed as catalysts to critically assess hydrogen production in a 150 L MEC pilot plant treating sugar-based industrial wastewater. Continuous hydrogen production was achieved in the reactor for more than 80 days, with a maximum COD removal efficiency of 40 %. Nickel-foam cathodes significantly enhanced hydrogen production and energy efficiency at non-limiting substrate concentration, yielding the maximum hydrogen production ever reported at pilot-scale (19.07 ± 0.46 L H2 m−2 d−1 and 0.21 ± 0.01 m3 m−3 d−1). This is a 3.0-fold improve in hydrogen production compared to the previous stainless-steel wool cathode. On the other hand, the higher price of Ni-foam compared to stainless-steel should also be considered, which may constrain its use in real applications. By carefully analysing the energy balance of the system, this study demonstrates that MECs have the potential to be net energy producers, in addition to effectively oxidize organic matter in wastewater. While higher applied potentials led to increased energy requirements, they also resulted in enhanced hydrogen production. For our system, a conservative applied potential range from 0.9 to 1.0 V was found to be optimal. Finally, the microbial community established on the anode was found to be a syntrophic consortium of exoelectrogenic and fermentative bacteria, predominantly Geobacter and Bacteroides, which appeared to be well-suited to transform complex organic matter into hydrogen.

Enhanced reaction extraction distillation via multi-objective optimization and 4E analysis for sustainable recovery of organic compounds from wastewater

Resource utilization and sustainable treatment of wastewater, which can achieve efficient energy utilization and environmental protection, have received hot social attention. Tetrahydrofuran and methanol are the two most common substances in pharmaceutical wastewater. It is very necessary to explore the wastewater treatment process containing these two substances. In this study, extractive distillation and reactive distillation were proposed to effectively separate the tetrahydrofuran-methanol-water component of pharmaceutical wastewater. To further reduce energy consumption, two strengthening processes, double-column reactive-extractive distillation and reactive-extractive dividing wall column distillation were designed. Taking the minimum operating and equipment cost as the objective function, the processes were optimized by using the multi-objective genetic optimization algorithm to obtain the best process parameters. Four processes were evaluated in terms of total annual cost, energy consumption, gas emissions and thermodynamic efficiency. Compared to the traditional three-column extractive distillation process, the above-mentioned four aspects of the reactive-extractive dividing wall column process was reduced by 40.63%, 43.13%, 43.14% and 17.71%, respectively. The reactive-extractive dividing wall column distillation process is of great significance for the efficient purification of valuable organic matter in wastewater and environmental protection.

Wastewater Surveillance of US Coast Guard Installations and Seagoing Military Vessels to Mitigate the Risk of COVID-19 Outbreaks, March 2021-August 2022.

Military training centers and seagoing vessels are often environments at high risk for the spread of COVID-19 and other contagious diseases, because military trainees and personnel arrive after traveling from many parts of the country and live in congregate settings. We examined whether levels of SARS-CoV-2 genetic material in wastewater correlated with SARS-CoV-2 infections among military personnel living in communal barracks and vessels at US Coast Guard training centers in the United States. The Coast Guard developed and established 3 laboratories with wastewater testing capability at Coast Guard training centers from March 2021 through August 2022. We analyzed wastewater from barracks housing trainees and from 4 Coast Guard vessels for the presence of SARS-CoV-2 genes N and E and quantified the results relative to levels of a fecal indicator virus, pepper mild mottle virus. We compared quantified data with the timing of medically diagnosed COVID-19 infection among (1) military personnel who had presented with symptoms or had been discovered through contact tracing and had medical tests and (2) military personnel who had been discovered through routine surveillance by positive SARS-CoV-2 antigen or polymerase chain reaction test results. Levels of viral genes in wastewater at Coast Guard locations were best correlated with diagnosed COVID-19 cases when wastewater testing was performed twice weekly with passive samplers deployed for the entire week; such testing detected ≥1 COVID-19 case 69.8% of the time and ≥3 cases 88.3% of the time. Wastewater assessment in vessels did not continue because of logistical constraints. Wastewater testing is an effective tool for measuring the presence and patterns of SARS-CoV-2 infections among military populations. Success with wastewater testing for SARS-CoV-2 infections suggests that other diseases may be assessed with similar approaches.

Electrocatalytic and photocatalytic activities of two alkynyl Ag20 cage clusters involved ligand exchange between PhCOO− and CF3COO−

Two silver alkynyl clusters, [(CO32−)@Ag20(tBuC≡C)14(PhCOO)3(CF3COO)] (1) and [(CO32−)@Ag20(tBuC≡C)14(PhCOO)(CF3COO)3] (2), composed of alkynyl Ag20 shell templated by a CO32− anion and supported by carboxyl ligands PhCOO− and CF3COO−, were synthesized successfully by conventional methods. Single crystal X–ray diffractometer (SCXRD) was used to determine the precise structures of 1 and 2. Although compounds 1 and 2 have the [(CO32−)@Ag20(tBuC≡C)14]4+ unit, the numbers of PhCOO− and CF3COO− ligands along with Ag···Ag interactions were affected by the steric hindrance of different carboxyl ligands and their concentrations. That is, compounds 1 and 2 separately contain the [(CO32−)@Ag20(tBuC≡C)14(PhCOO)(CF3COO)]2+ unit, which is involved in the ligand exchange between PhCOO− and CF3COO−. Powder X-ray diffraction (PXRD), fourier transform infrared spectroscopy (FT-IR), and thermogravimetric analysis (TGA) were used to characterized compounds 1 and 2. The photocurrent responses, absorption spectra, as well as luminescence of 1 and 2 have been studied. In addition, the reduction of H2O2 for GCE–1 and GCE–2 showed good electrocatalytic activity, and catalysts 1 and 2 showed good photocatalytic degradation efficiency of methylene blue (MB). The results suggest that 1 and 2 can act as new electrocatalysts and photocatalysts to detect and decompose organic pollutants and hazardous materials in wastewater.

Assessing microbial exoelectrogenicity for enhanced industrial waste water management and power generation

The quest for eco-friendly waste management and renewable sources of energy is rapidly increasing. Microbial fuel cell is promising form of renewable energy, which treat and convert organic matter in wastewater to electricity through the aid of microorganisms present in the wastewater. This study assessed for electrogenic microorganisms that generate power during wastewater treatment at a referenced pH of 8.5 and temperature of 37 0C. The exoelectrogenicity and identity of the microbial isolates were confirmed using microbial fuel cell (MFC) and molecular characterization, respectively. Two bacterial isolates: N4- Providencia species, N6- Proteus species, and three fungal isolates: S9- Clavispora lusitaniae, S10- Candida parapsilosis ,S14- Clavispora lusitaniae with accession numbers; KX548357.1, KX548358.1 and KX548359.1, KX548360.1, KX548361.1, respectively showed exoelectrogenic properties. Proteus species and Candida parapsilosis generated relative high-power densities of 1.59 and 1.55 W/m2, respectively. Significant difference (p < 0.05) in wastewater treatment was also observed. When compared with the control wastewater, S10 recorded about 38% of contaminant removal with the following parameters; biochemical oxygen demand (536.38mg/l), chemical oxygen demand (1974mg/l), total dissolved solid (640mg/l) and conductivity (512µS/cm). The findings showed that, not only bacteria, but fungi are good exoelectrogenic microorganisms for industrial wastewater treatment and power generation in MFC setup.

Enhanced Removal of Dissolved Effluent Organic Matter in Wastewater Using Lignin-Based Biochar Supported Fe–Cu Bimetallic Oxide Catalyst

The effluent discharged from wastewater treatment facilities frequently enters the ocean, posing a considerable threat to the health of marine life and humans. In this paper, an alkali lignin-based biochar-loaded modified Fe–Cu catalyst (FeCu@BC) was prepared to remove soluble microbial products (SMP) from secondary effluent as disinfection by-products precursors at ambient temperature and pressure. The humic acid (HA) was taken as the representative substance of SMP. The results showed that the maximum removal efficiency of HA reached 93.2% when the FeCu@BC dosage, pH, initial HA concentration, and dissolved oxygen concentration were 5.0 g/L, 7, 100 mg/L, and 1.75 mg/L, respectively. After three cycles, the removal efficiency of HA could be maintained at more than 70%. The quenching experiments and electron spin resonance (EPR) results showed that •OH and 1O2 were involved in the degradation of HA in the FeCu@BC catalyst reaction system, with 1O2 playing a dominant role. Theoretical calculations confirmed that •OH and 1O2 were more prone to attack the C=O bond of the side chain of HA. After processing by the FeCu@BC catalyst, the yield of chlorinated disinfection by-products from secondary effluent had decreased in an obvious manner. This study provides a new solution to efficiently solve the problem of chlorinated disinfection by-products from HA.

Electrochemical Oxidation Treatment of Organic Matter in Wastewater from Wet Fermentation of Yunnan Arabica Coffee

Electrochemical oxidation combined with reagents of O3, H2O2 and FeCl2 was conducted in this study to treat the wastewater from wet fermentation of Yunnan arabica coffee. In addition, the effect of oxidants on the efficiency of wastewater treatment, the binding capacities of the oxidants to proteins, the degradation of organic pollutants in the wastewater, and the formation of oxidized organic components were systematically investigated. The results reveal better performance of O3-combined electrochemical oxidation (63.60% COD removal efficiency) for treatment of organic species in coffee wastewater than that of the electrochemical processes with H2O2 (47.70% COD removal efficiency) and FeCl2 (34.48% COD removal efficiency). The synergy of the electrooxidation/O3 process (0.0133 A/cm2, 20 mg/L–2 L/min) could not only raise the pH value (3.70~4.20, 5.14~5.44) of the wastewater and reduce the NaOH dosage of 2.80~3.7 g/L, but also effectively degrade the proteins, lipids, unsaturated hydrocarbons, and carbohydrates, with a total chemical oxygen demand (COD) value above 20,000 mg/L. After the oxidation treatment, some organic components remained in the wastewater, including 31.94% of S-containing organics, lignin, condensed aromatic compounds, and aromatic structural compounds, which are difficult to be utilized by microorganisms. In addition, it was found that OH− could bind to proteins and affect the required amount of NaOH addition, whereas the protein binding energy of O3 is higher than that of H2O2, indicating a stronger ability of O3 to oxidize proteins. Therefore, the combination of O3 and electrochemical oxidation can be considered as an effective method to treat organic pollutants in the wastewater from wet fermentation of Yunnan arabica coffee.

Insight into activation of peroxymonosulfate by Fe2O3 and MoN co-doped nitrogen-rich carbon to removal of bisphenol A: Singlet oxygen and electron transfer

In this study, zeolite imidazolate framework-8 (ZIF-8) was utilized as a nitrogen-rich porous carbon substrate (NC) loaded with Fe2O3 and MoN to prepare bimetallic nanocatalysts (FeMo@NC) with synergistic catalytic effect. The optimized Fe0.05Mo0.05 @NC exhibited excellent performance in activating PMS and could completely remove BPA from water within 60 min. The results showed that the introduction of molybdenum significantly lowered the energy barrier for the generation of 1O2 and significantly increased the degree of graphitization and specific surface area of the catalysts, which facilitated the direct electron transfer and adsorption of target substances. The electron transfer of the surface complexes and 1O2 jointly induced the non-radical oxidation of BPA. In addition, the system was suitable for a wide pH range (pH=3–9) and resistant to background organic matter in wastewater. Our work elucidated the mechanism of transition metal Mo to enhance the catalytic performance of heterogeneous iron-based catalysts, which provided a new aspect for the development of catalysts with high efficiency for PMS activation.

Potential stimulation of nitrifying bacteria activities and genera by landfill leachate

With the increasing complexity of influent composition in wastewater treatment plants, the potential stimulating effects of refractory organic matter in wastewater on growth characteristics and genera conversion of nitrifying bacteria (ammonium-oxidizing bacteria [AOB] and nitrite-oxidizing bacteria [NOB]) need to be further investigated. In this study, domestic wastewater was co-treated with landfill leachate in the lab-scale reactor, and the competition and co-existence of NOB genera Nitrotoga and Nitrospira were observed. The results demonstrated that the addition of landfill leachate could induce the growth of Nitrotoga, whereas Nitrotoga populations remain less competitive in domestic wastewater operation. In addition, the refractory organic matter in the landfill leachate also would have a potential stimulating effect on the maximum specific growth rate of AOB genus Nitrosomonas (μmax, aob). The μmax, aob of Nitrosomonas in the control group was estimated to be 0.49 d−1 by fitting the ASM model, and the μmax, aob reached 0.66–0.71 d−1 after injection of refractory organic matter in the landfill leachate, while the maximum specific growth rate of NOB (μmax, nob) was always in the range of 1.05–1.13 d−1. These findings have positive significance for the understanding of potential stimulation on nitrification processes and the stable operation of innovative wastewater treatment process.

Enhancement of microbial fuel cell performance by introducing dosing materials in waste water to increase microorganism growth

This study uses the microbial electrochemical process to produce energy from wastewater. The bacterial growth in sewage has been controlled by applying molasses, vegetables and waste coffee as dosing materials. High-conductive silver metal has been used as an anode, whereas graphite has been used as a cathode. An agar salt membrane has been used as a separator to ensure high hydrogen-ion exchange. During bacterial culture, it is revealed that 21,600,000 cfu/ml, 14,800,000 cfu/ml, and 38,700,000 cfu/ml number of bacteria is observed for molasses, vegetable protein and waste coffee, respectively. In each dosing, E.coli, S.aureus, and Salmonella sp. were identified. The bacterial growth highly influenced electrical energy production in this method. The wastage of coffee produced more energy and grew more bacteria. Waste coffee had a maximum current density of 809.40 mA/m2 and a maximum power density of 10622.496 mW/m2, respectively. In contrast, the minimum current and power density values, 166.15 mA/m2 and 408.726 mW/m2, were attained, respectively. The produced energy is much higher than the information available in the literature. The applied method can be used in various sectors to generate electrical energy.