Development of a Polymeric Carbon Nanocomposite Hollow-Fiber Membrane for Wastewater Treatment.

This study investigated experimental parameters to fabricate polymeric carbon nanocomposite hollow-fiber membranes with graphene oxide and multi-walled carbon nanotubes. This case was different from that of flat-sheet type membranes in that the characteristics of the hollow-fiber type membranes were affected by the structure of the spinneret, the flow rate of the injected polymer and draw solution, and the mixing ratio. The membranes were characterized in terms of mechanical strength, porosity, hydrophilicity, and permeate flux using different solutions. The results reveal a mechanical strength of the carbon nanocomposite hollow-fiber membranes that is about 47.8% higher than that of hollow-fiber membranes without carbon nanomaterials. The porosity and surface hydrophilicity changed to produce more applicable membranes for water and wastewater treatment. As for the permeate flux, the nanocomposite membrane with graphene oxide showed a higher flux compared to the multi-walled carbon nanotubes membrane, which could be influenced by structural effects of the carbon materials.

Biological fixed-film systems.

The technical papers published in 2019 regarding wastewater treatment and microbial films were classified into two categories: biofilm and biofilm reactors. The biofilm category includes biofilm formation, biofilm consortia, bacterial signals, biofouling, extracellular polymeric substances, and biofilm membrane bioreactors. The biofilm reactors category provides recent information on rotating biological contactors, fluidized-bed biofilm reactors, integrated fixed-film activated sludge, moving-bed biofilm reactors, packed-bed biofilm reactors, sequencing biofilm batch reactors, and trickling filters.

Removal of Heavy Metal Ion in Wastewater by Dendritic Nano-Structured Complex Material.

The specific adsorbents for the removal of heavy metal were synthesized by polyamidoamine dendrimer and blast furnace slag, and their physico-chemical properties were evaluated in this study. The batch experiment was evaluated the adsorptive water treatment capability of adsorbent, and the zeta potential and surface morphology were analyzed for evaluating of the material. In result, 10% volume loading adsorbent presented the high yields of heavy metal adsorption in water phase, and Cr (III) interacted highly with dendrimer adsorbents. Furthermore, it was evaluated that the adsorption properties of dendrimer adsorbent were increased with increasing the ligand-to-metal charge-transfer.

Biological Fixed Film.

The review includes scientific literatures published in the year of 2017 regarding the uses of biofilm and bioreactor to treat wastewater. Topics considered are: biofilm formation and factors that impact biofilm formation; extracellular polymeric substance from biofilms; biofilm consortia and quorum sensing; biofilm associated phage; biofilm reactors; and biofilm in bioelectrochemical systems.

Environmental Applications of Nano-Sized Recycled Aggregates: The Effect of Sterilization and Adsorption.

To evaluate the sterilize efficiency of nano-sized recycled aggregates (RAs), several types of RAs were examined for the purpose of environmental stamping out procedure. The poultry (e.g., chicken) was selected as a target livestock of epidemic disease, and the blast furnace slag (BFS), fly ash (FA), slaked lime (SL), nano-cerium (n-Ce) and shell (Sh) were used as the RAs materials. The fermented solution of effective microorganisms (EM) was added to decompose the target livestock. Various kinds of lab-scale reactor were operated to examine the effects of RAs volume; high and low volume of RAs (e.g., 1.89 w/v% and 1.14 w/v% of RA in solution, respectively), and the effects of EM concentration (e.g., concentrated solution (100%) and diluted solution (12.5%)) with tested in different reaction time. The number of microorganisms after batch tests was counted for the sterilized effects of RAs, and organic matters (e.g., chemical oxygen demand (COD)) and inorganic matters (e.g., suspended solids (SS), heavy metals and potential ions) were analyzed before and after adsorption process. The cases of SL and n-Ce showed high removal of microorganism in the batch of high concentrated EM for 20 days. However the other RA materials were less effective on the sterilization especially in lower volume of RAs. In diluted EM (e.g., 12.5%) tests, most RAs have high sterilization efficiencies in the short periods of batch reaction regardless of RAs types, and it was more effective with longer reaction time. The BFS and n-Ce exhibited higher surface area than others and they adsorbed highly heavy metals in water. The results suggested that the concentration of target organism was the most important to determine sterilization and adsorption properties of RAs.

Biological Fixed Film.

The review includes scientific and technical literature published in the year of 2016 regarding the uses of biofilm and bioreactors to treat wastewater. Topics considered are: biofilm formation and factors that impact biofilm formation; extracellular polymeric substances (EPS) from biofilms; biofilm consortia, quorum sensing and quenching; biofilm reactors and biofilm in bioelectrochemical systems.

Microbial community analysis of bulk sludge/cake layers and biofouling-causing microbial consortia in a full-scale aerobic membrane bioreactor.

Pyrosequencing was used to investigate biofouling-causing microbial consortia at the community level in bulk sludge and cake layers within a full-scale membrane bioreactor (MBR). The analysis revealed Chao's estimates of total operational taxonomic units (OTUs) of 1726, 1806, and 1362 for bulk sludge, cake outer layer, and cake inner layer, respectively. The bulk sludge and cake outer layer OTUs clustered together, whereas the cake inner layer OTUs formed a separate group, indicating that environmental conditions affected the microbial community composition within the MBR. Bacteroidetes, Proteobacteria, and Chloroflexi were the dominant phyla in both the bulk sludge and the cake layers. Comparison at the genus level showed twelve distinct genera in the cake layers that were absent in bulk sludge. Twenty distinct genera were recorded in the inner cake layer. Those genera are likely the microbial colonization pioneers in full-scale membrane bioreactors.

Biological Fixed Film.

The review includes literature published in the year of 2015 regarding the uses of biofilm in full-scale and lab-scale bioreactors to treat wastewater. The topics considered include biofilm formation and factors impacting biofilm formation; extracellular polymeric substance from biofilms; biofilm consortia and quorum sensing; biofilm reactors and biofilm in bioelectrochemical systems.

Adsorption of Magnesium Sulfate from Desulfurization Industrial Wastewater by Nano-Cerium Loaded Recycled Aggregates.

In this research, the recycled aggregates (RAs) from blast furnace were solidified with nano-cerium (Ce), and applied to reduce the ionic species (e.g., magnesium sulfate) in the desulfurization industrial wastewater. Static batch experiments were performed based on different loading of recycled aggregates. Sulfate sorption isotherm studies were performed by Langmuir adsorption model. The physical morphologies were determined using scanning electron microscope. The results presented that the partial ions were captured with the different loading of the recycled aggregates during the batch tests. It was observed that 8 hr batch reaction equilibrated the electrical conductivity reduction, and 13% mass loading was estimated an optimal dosage of adsorbent. This study showed the nano-Ce loaded RAs could reduce ionic species in wastewater, and expected to be an economical adsorbent for wastewater treatment process.

Desalination of Basal Water by Mesoporous Carbons Nanocomposite Membrane.

The hydro-transportation process used to obtain bitumen from the Alberta oil sands produces large volume of basal depressurization water (BDW), which contains high salt concentrations. In this research, thin-film nanocomposite (TFN) membrane technology applied to treat BDW in lab-scale, and evaluated water properties before and after the treatment. The average rejection ratios of ionic species were 95.2% and 92.8% by TFN membrane (with ordered mesoporous carbons (OMCs)) and thin-film composite (TFC) (without OMCs) membrane, respectively. The turbidity and total dissolved solids (TDS) were completely rejected in all treatment conditions. Interestingly, the water flux of TFN membrane was dramatically increased compared to TFC membrane. The increase of water flux was believed to be caused by the increased membrane surface hydrophilicity and nano-pore effects by the OMCs.

Biological Fixed Film.

The review includes literatures published in the year of 2014 regarding the uses of biofilm and bioreactor to treat wastewater. Topics considered are: biofilm formation and factors that impact biofilm formation; extracellular polymeric substance from biofilms; biofilm consortia and quorum sensing; biofilm reactors and biofilm in bioelectrochemical systems.

Bacteriophage therapy for membrane biofouling in membrane bioreactors and antibiotic-resistant bacterial biofilms.

To demonstrate elimination of bacterial biofilm on membranes to represent wastewater treatment as well as biofilm formed by antibiotic-resistant bacterial (ARB) to signify medical application, an antibiotic-resistant bacterium and its lytic bacteriophage were isolated from a full-scale wastewater treatment plant. Based on gram staining and complete 16 S rDNA sequencing, the isolated bacterium showed a more than 99% homology with Delftia tsuruhatensis, a gram-negative bacterium belonging to ß-proteobacteria. The Delftia lytic phage's draft genome revealed the phage to be an N4-like phage with 59.7% G + C content. No transfer RNAs were detected for the phage suggesting that the phage is highly adapted to its host Delftia tsuruhatensis ARB-1 with regard to codon usage, and does not require additional tRNAs of its own. The gene annotation of the Delftia lytic phage found three different components of RNA polymerase (RNAP) in the genome, which is a typical characteristic of N4-like phages. The lytic phage specific to D. tsuruhatensis ARB-1 could successfully remove the biofilm formed by it on a glass slide. The water flux through the membrane of a prototype lab-scale membrane bioreactor decreased from 47 L/h m(2) to ∼15 L/h m(2) over 4 days due to a biofilm formed by D. tsuruhatensis ARB-1. However, the flux increased to 70% of the original after the lytic phage application. Overall, this research demonstrated phage therapy's great potential to solve the problem of membrane biofouling, as well as the problems posed by pathogenic biofilms in external wounds and on medical instruments.

Enhanced bioelectricity harvesting in microbial fuel cells treating food waste leachate produced from biohydrogen fermentation.

Microbial fuel cells (MFCs) treating the food waste leachate produced from biohydrogen fermentation were examined to enhance power generation and energy recovery. In batch mode, the maximum voltage production was 0.56 V and the power density reached 1540 mW/m(2). The maximum Coulombic efficiency (CEmax) and energy efficiency (EE) in the batch mode were calculated to be 88.8% and 18.8%, respectively. When the organic loading rate in sequencing batch mode varied from 0.75 to 6.2 g COD/L-d (under CEmax), the maximum power density reached 769.2 mW/m(2) in OLR of 3.1 g COD/L-d, whereas higher energy recovery (CE=52.6%, 0.346 Wh/g CODrem) was achieved at 1.51 g COD/L-d. The results demonstrate that readily biodegradable substrates in biohydrogen fermentation can be effectively used for the enhanced bioelectricity harvesting of MFCs and a MFC coupled with biohydrogen fermentation is of great benefit on higher electricity generation and energy efficiency.

Power generation and oil sands process-affected water treatment in microbial fuel cells.

Oil sands process-affected water (OSPW), a product of bitumen isolation in the oil sands industry, is a source of pollution if not properly treated. In present study, OSPW treatment and voltage generation were examined in a single chamber air-cathode microbial fuel cell (MFC) under the effect of inoculated carbon source and temperature. OSPW treatment with an anaerobic sludge-inoculated MFC (AS-MFC) generated 0.55 ± 0.025 V, whereas an MFC inoculated with mature-fine tailings (MFT-MFC) generated 0.41 ± 0.01 V. An additional carbon source (acetate) significantly improved generated voltage. The voltage detected increased to 20-23% in MFCs when the condition was switched from ambient to mesophilic. The mesophilic condition increased OSPW treatment efficiency in terms of lowering the chemical oxygen demand and acid-extractable organics. Pyrosequencing analysis of microbial consortia revealed that Proteobacteria were the most abundant in MFCs and microbial communities in the AS-MFC were more diverse than those in the MFT-MFC.

Increased power generation from primary sludge in microbial fuel cells coupled with prefermentation.

Raw primary sludge and the prefermentation liquor (PL) of primary sludge were used to generate electricity in single-chambered air-cathode microbial fuel cells (MFCs). The MFCs treating the primary sludge produced 0.53 V and 370 mW/m(2) for the maximum potential and power density, respectively. In the primary sludge-fed MFCs, only 5 % of the total energy production was produced from direct electricity generation, whereas 95 % of that resulted from the conversion of methane to electricity. MFCs treating the PL generated the maximum potential of 0.58 V and maximum power density of 885 mW/m(2), respectively. In the energy production analysis, direct electricity production (1,921 Wh/kg TCODrem) in the MFCs treating the PL was much higher than that of the primary sludge-fed MFC (138 Wh/kg TCODrem). Volatile suspended solids during 10 days were reduced to 18.3 and 38 % in the primary sludge-fed MFCs and prefermentation reactor, respectively. These findings suggest that a two-stage process including prefermentation and MFCs is of great benefit on sludge reduction and higher electricity generation from primary sludge.

Comparative performance of air-lift partial nitritation processes with attached growth and suspended growth without biomass retention.

Partial nitritation is an essential first step in anaerobic ammonium oxidation. This study compared the performance of air-lift partial nitritation reactors with attached growth (AG) and suspended growth (SG) without biomass retention using ammonium-rich recirculated liquor produced from the dewatering of anaerobically digested sludge. The steady-state results showed that the AG can effectively retain ammonium-oxidizing bacteria (AOB) with high activity and allow minimizing biomass discharge (approximately 10 mg volatile suspended solids/L) in the effluent. The nitrogen loading (based on the total reactor volume) satisfying the effluent characteristics could be suggested to be 0.42 g N/L/d for the SG, and 0.76 g N/L/d for the AG, respectively. Compared with the SG, the AG achieved a higher ammonium loading rate (approximately 1.8 times), maximal ammonium oxidation activity (48 mg N/L-h based on liquid-phase volume) under a short hydraulic retention time (HRT) and a long solids retention time (SRT > 80 d). The overall performance confirmed that AG is a promising configuration for partial nitritation in terms of the process stability, maximization of the AOB activity and minimization of the effluent biomass under a short HRT and high nitrogen loading rate.

Continuous electricity generation in stacked air cathode microbial fuel cell treating domestic wastewater.

This study examined the continuous performance of air cathode MFC stacks for domestic wastewater treatments at two different temperatures (23 ± 3 °C and 30 ± 1 °C) and organic loading rates to determine the effects of the electrode connection and hydraulic flow mode on the stack performance. The power density and process stability were affected significantly by the electrode connection type, flow mode, and operating parameters. The parallel electrode connection system (in series flow mode) had benefits of COD removal, Coulombic efficiency and maximal power density due to the higher stability of the ORP in overall cells. The highest power density of 420 mW/m(2) (12.8 W/m(3)) was achieved in series flow and parallel connection mode at an organic loading rate of 25.6 g COD/L-d (HRT of 0.33 h) under mesophilic conditions, achieving a COD removal of 44%. The results highlight the importance of prefermentation process in the application of a stacked MFC for an actual wastewater treatment.

Bacteriophage-based biocontrol of biological sludge bulking in wastewater.

In a previous paper, the first ever application of lytic bacteriophage (virus)-mediated biocontrol of biomass bulking in the activated sludge process using Haliscomenobacter hydrossis as a model filamentous bacterium was demonstrated. In this work we extended the biocontrol application to another predominant filamentous bacterium, Sphaerotilus natans, notoriously known to cause filamentous bulking in wastewater treatment systems. Very similar to previous study, one lytic bacteriophage was isolated from wastewater that could infect S. natans and cause lysis. Significant reduction in sludge volume index and turbidity of the supernatant was observed in batches containing S. natans biomass following addition of lytic phages. Microscopic examination confirmed that the isolated lytic phage can trigger the bacteriolysis of S. natans. This extended finding further strengthens our hypothesis of bacteriophage-based biocontrol of overgrowth of filamentous bacteria and the possibility of phage application in activated sludge processes, the world's widely used wastewater treatment processes.

Biocontrol of biomass bulking caused by Haliscomenobacter hydrossis using a newly isolated lytic bacteriophage.

This research demonstrates the first ever application of lytic bacteriophage (virus) mediated biocontrol of biomass bulking in the activated sludge process using Haliscomenobacter hydrossis as a model filamentous bacterium. Bacteriophages are viruses that specifically infect bacteria only. The lytic phage specifically infecting H. hydrossis was isolated from the mixed liquor of a local wastewater treatment plant. The isolated bacteriophage belongs to the Myoviridae family with a contractile tail (length-126 nm; diameter-18 nm) and icosahedral head (diameter-81 nm). Titer of the isolated phage with H. hydrossis was calculated to be 5.2 ± 0.3 × 10(5) PFU/mL and burst size was found to be 105 ± 7 PFU/infected cell. The phage was considerably stable after exposure to high temperature (42 °C) and pH between 5 and 8, emphasizing that it can withstand the seasonal/operational fluctuations under real-time applications. Phage to host (bacteria) ratio for the optimal infection was found to be 1:1000 with ∼54% host death. The isolated phage showed no cross infectivity with other bacteria most commonly found in activated sludge systems, thus validating its suitability for biocontrol of filamentous bulking caused by H. hydrossis. Following the phage application, successful reduction in sludge volume index (SVI) from 155 to 105 was achieved, indicating improved biomass settling. The application of phage did not affect nutrient removal efficiency of the biomass, suggesting no collateral damage. Similar to phage therapy in medical applications, phage-mediated biocontrol holds a great potentiality for large-scale applications as economic agent in the mitigation of several water, wastewater and environmental problems. Present study in this direction is a novel effort.

Various physico-chemical stress factors cause prophage induction in Nitrosospira multiformis 25196--an ammonia oxidizing bacteria.

Bacteriophages are viruses that infect bacteria and contribute significant changes in the overall bacterial community. Prophages are formed when temperate bacteriophages integrate their DNA into the bacterial chromosome during the lysogenic cycle of the phage infection to bacteria. The prophage (phage DNA integrated into bacterial genome) on the bacterial genome remains dormant, but can cause cell lysis under certain environmental conditions. This research examined the effect of various environmental stress factors on the ammonia oxidation and prophage induction in a model ammonia oxidizing bacteria Nitrosospira multiformis ATCC 25196. The factors included in the study were pH, temperature, organic carbon (COD), the presence of heavy metal in the form of chromium (VI) and the toxicity as potassium cyanide (KCN). The selected environmental factors are commonly encountered in wastewater treatment processes, where ammonia oxidizing bacteria play a pivotal role of converting ammonia into nitrite. All the factors could induce prophage from N. multiformis demonstrating that cell lysis due to prophage induction could be an important mechanism contributing to the frequent upset in ammonia oxidation efficiency in full scale treatment plants. Among the stress factors considered, pH in the acidic range was the most detrimental to the nitrification efficiency by N. multiformis. The number of virus like particles (VLPs) increased by 2.3E+10 at pH 5 in 5h under acidic pH conditions. The corresponding increases in VLPs at pH values of 7 and 8 were 9.67E+9 and 1.57E+10 in 5h respectively. Cell lysis due to stress resulting in phage induction seemed the primary reason for deteriorated ammonia oxidation by N. multiformis at lower concentrations of Cr (VI) and potassium cyanide. However, direct killing of N. multiformis due to the binding of Cr (VI) and potassium cyanide with cell protein as demonstrated in the literature at higher concentrations of these toxic compounds was the primary mechanism of cell lysis of N. multiformis. Organics represented by the chemical oxygen demand (COD) did not have any effect on the phage induction in N. multiformis. This AOB remained dormant at low temperature (4 degrees C) without any phage induction. Significant decrease in the number of live N. multiformis cells with a corresponding increase in the number of VLPs was recorded when the temperature was increased to 35 degrees C. Death of N. multiformis at 45 degrees C was attributed to the destruction of cell wall rather than to the phage induction.