Bin Ji, Siqi Fan, Y. Liu

SSRN Electronic Journal • 2022

This study developed a continuous-flow non-aerated microalgal-bacterial granular tubular reactor for aquaculture wastewater treatment under natural day-night conditions. Results showed that daytime was favorable for ammonia removal while nighttime for nitrate removal. Over 99% of nitrite-N could be removed over the day-night cycles at a hydraulic retention time of 6 h. However, the phosphorus removal was found to be sensitive to the weather condition, ranging from 35.3% to 96.6%. It was also observed that dissolved oxygen produced by microalgae in daytime was sufficient for creating a 6-h aerobic condition in nighttime for sustaining heterotrophic activity. Chlorella and Leptolyngbya were identified as the most abundant algae related to weather changes. Metagenomics analysis revealed that the high nitrite removal relied mainly on nitrite reduction. These experimental findings offer new insights into the non-aerated microalgal-bacterial granular sludge for environmentally sustainable aquaculture wastewater treatment.

M. Dueholm, M. Nierychlo, K. S. Andersen et al.

• 2021

Microbial communities are responsible for biological wastewater treatment, but our knowledge of their diversity and function is still poor. Here, we sequence more than 5 million high-quality, full-length 16S rRNA gene sequences from 740 wastewater treatment plants (WWTPs) across the world and use the sequences to construct the ‘MiDAS 4’ database. MiDAS 4 is an amplicon sequence variant resolved, full-length 16S rRNA gene reference database with a comprehensive taxonomy from domain to species level for all sequences. We use an independent dataset (269 WWTPs) to show that MiDAS 4, compared to commonly used universal reference databases, provides a better coverage for WWTP bacteria and an improved rate of genus and species level classification. Taking advantage of MiDAS 4, we carry out an amplicon-based, global-scale microbial community profiling of activated sludge plants using two common sets of primers targeting regions of the 16S rRNA gene, revealing how environmental conditions and biogeography shape the activated sludge microbiota. We also identify core and conditionally rare or abundant taxa, encompassing 966 genera and 1530 species that represent approximately 80% and 50% of the accumulated read abundance, respectively. Finally, we show that for well-studied functional guilds, such as nitrifiers or polyphosphate-accumulating organisms, the same genera are prevalent worldwide, with only a few abundant species in each genus. Microbial communities are responsible for biological wastewater treatment. Here, Dueholm et al. generate more than 5 million high-quality, full-length 16S rRNA gene sequences from wastewater treatment plants across the world to construct a database with a comprehensive taxonomy, providing insights into diversity and function of these microbial communities.

R. Oruganti, Keerthi Katam, P. Show et al.

Bioengineered • 2022

ABSTRACT The scarcity of water resources and environmental pollution have highlighted the need for sustainable wastewater treatment. Existing conventional treatment systems are energy-intensive and not always able to meet stringent disposal standards. Recently, algal-bacterial systems have emerged as environmentally friendly sustainable processes for wastewater treatment and resource recovery. The algal-bacterial systems work on the principle of the symbiotic relationship between algae and bacteria. This paper comprehensively discusses the most recent studies on algal-bacterial systems for wastewater treatment, factors affecting the treatment, and aspects of resource recovery from the biomass. The algal-bacterial interaction includes cell-to-cell communication, substrate exchange, and horizontal gene transfer. The quorum sensing (QS) molecules and their effects on algal–bacterial interactions are briefly discussed. The effect of the factors such as pH, temperature, C/N/P ratio, light intensity, and external aeration on the algal-bacterial systems have been discussed. An overview of the modeling aspects of algal-bacterial systems has been provided. The algal-bacterial systems have the potential for removing micropollutants because of the diverse possible interactions between algae-bacteria. The removal mechanisms of micropollutants – sorption, biodegradation, and photodegradation, have been reviewed. The harvesting methods and resource recovery aspects have been presented. The major challenges associated with algal-bacterial systems for real scale implementation and future perspectives have been discussed. Integrating wastewater treatment with the algal biorefinery concept reduces the overall waste component in a wastewater treatment system by converting the biomass into a useful product, resulting in a sustainable system that contributes to the circular bioeconomy. Graphical Abstract

M. Medina, U. Neis

Water Science and Technology • 2007

Algal incorporation into the biomass is important in an innovative wastewater treatment that exploits the symbiosis between bacterial activated sludge and microalgae (Chlorella vulgaris sp. Hamburg). It allows a good and easy algae separation by means of clarification. The effect of process parameters food to microorganisms ratio (F/M) and hydraulic retention time (HRT) on the process performance, evaluated by settleability, microalgae incorporation to biomass and nutrient removal, was studied. HRT hinted at a significant influence in the growth rate of algae, while F/M turned out to be important for stability when algae are incorporated into the biomass. This parameter also affects the total nitrogen removal of the treatment. Stable flocs with incorporated algae and supernatants with low free swimming algae concentrations were obtained at high HRT and low F/M values.

Tadashi Shoji, Shuichi Ochi, Masaaki Ozaki

Water Science and Technology • 2008

<jats:p>The concern with wastewater reuse as a sustainable water resource in urban areas has been growing. For the reclamation and distribution of wastewater, biofilm development deserves careful attention from the point of view of its promotion (e.g. biofiltration) and inhibition (e.g. clogging and hygiene problems). As the first step to control biofilm development, bacterial biofilm communities in tertiary treatment processes were characterized by using molecular biological methods. The result of clone library analysis showed that Nitrospirae-related (nitrite-oxydizing bacteria) and Acidobacteria-related (probably oligotrophic bacteria) groups were dominant. The ratio of the Nitrospirae-related group to the Acidobacteria-related group was associated with ammonia load, whereas other operational conditions (process, media, temperature, salt) did not clearly affect the phylum-level community or the dominant sequence of nitrifying bacteria. The result of real-time PCR also indicated that high ammonia load promotes the proliferation of nitrite- and ammonia-oxidizing bacteria. Regarding water supply systems, some researchers also have suggested the dominance of Nitrospirae- and Acidobacteria-related groups in biofilm formed on water distribution pipes. In tertiary wastewater treatment, therefore, it is concluded that oligotrophic and autotrophic bacteria are the dominant groups in biofilm samples because assimilable organic carbon is too poor to proliferate various heterotrophic bacteria.</jats:p>

J. B. Carberry, C. M. Brunner

Water Science and Technology • 1991

<jats:p>Carberry's proposed algal bacterial clay treatment (ABCT) process would generate an algal biomass, useful as a food source. This study examined the diurnal fluctuations resulting from alternating light-dark periods and the magnitude of resulting O2, CO2, and pH oscillations. The magnitude of these oscillations was studied under controlled conditions, in order to determine acceptable limits of these fluctuations. The effects of progressive drifts for these parameter values under uncontrolled conditions was also studied in order to determine the rate of decreasing wastewater bacterial biodegradation efficiency and rate of deterioration of algal biomass viability. Experiments were conducted in which algae, bacteria, and substrate were combined at various concentrations in a biostat. Dissolved gas concentrations and pH were continuously recorded; biomass and substrate concentrations were determined over time by periodic sampling. A 12-hour light/dark cycle simulated the natural diurnal light variation. Based on results from these runs, two computer programs were developed to predict the changes in these parameters over a 24-hour period. One model, incorporating redox potential, appeared to be more sensitive to changes in the aqueous environment than the model based on COD. pH values of less that 5 were found to cause system failure due to a continuing decrease in algal concentration. No critical levels were found for either O2 or CO2 although the duration of time spent at a dissolved oxygen concentration of zero depended on initial algal concentration.</jats:p>

Amir H. Tehrani, Kimberley A. Gilbride

MicrobiologyOpen • 2018

<jats:title>Abstract</jats:title><jats:p>The conventional biological treatment process can provide a favorable environment for the maintenance and dissemination of antibiotic‐resistant bacteria and the antibiotic resistance genes (ARG) they carry. This study investigated the occurrence of antibiotic resistance in three wastewater treatment plants (WWTP) to determine the role they play in the dissemination of ARGs. Bacterial isolates resistant to tetracycline were collected, and tested against eight antibiotics to determine their resistance profiles and the prevalence of multiple antibiotic resistance. It was found that bacteria resistant to tetracycline were more likely to display resistance to multiple antibiotics compared to those isolates that were not tetracycline resistant. Polymerase chain reaction (PCR) was used to identify the tetracycline resistance determinants present within the bacterial communities of the WWTPs and receiving waters, and it was found that ARGs may not be released from the treatment process. Identification of isolates showed that there was a large diversity of species in both the tetracycline‐resistant and tetracycline‐sensitive populations and that the two groups were significantly different in composition. Antibiotic resistance profiles of each population showed that a large diversity of resistance patterns existed within genera suggesting that transmission of ARG may progress by both horizontal gene and vertical proliferation.</jats:p>

G. Gutzeit, D. Lorch, A. Weber et al.

Water Science and Technology • 2005

<jats:p>An innovative technology for the biological treatment of wastewater in regions with sufficient solar radiation based on the simultaneous growth and degradation processes of algal and bacterial biomass is presented. The aim of the work is the improvement of pond technology through the formation of stable algae–bacteria aggregates, which a) permit a simple separation of the algal biomass by gravity sedimentation, b) enable a high removal efficiency for organic carbon and nutrients, and c) are independent in terms of oxygen provision through algal photosynthesis. Algae–bacteria aggregates could be developed with a suitable algal species (Chlorella vulgaris, Strain Hamburg) as a ‘model organism’ in a wastewater environment. The morphology of algal–bacterial flocs is similar to activated sludge flocs. They are stable and settle quickly. Floc size ranged between 400 and 800μm. Results of our experiments with an artificially irradiated lab-scale system, operated in continuous flow mode, revealed that even at a relatively short hydraulic detention time of two days, a high elimination capacity of 9.96g Nm−2d−1 and 0.87g Pm−2d−1 can be achieved. Recent investigations confirmed that floc formation of unicellular algae and wastewater bacteria also could be developed and maintained in a pilot-scale system with a water depth of 0.5m.</jats:p>

N.P. Dan, C. Visvanathan, C. Polprasert et al.

Water Science and Technology • 2002

<jats:p>Two laboratory-scale membrane bioreactor systems were investigated to treat high salinity wastewater containing high organic (5,000 mg/L COD) and salt content (32 g/L NaCl), namely: (1) the Yeast Membrane Bioreactor (YMBR) and; (2) Yeast pretreatment followed by Bacterial Membrane Bioreactor (BMBR). In the YMBR system, experimental runs were conducted with a mean biomass concentration of 12 g MLSS/L. Here the maximum COD removal rate of 0.93 g COD/g MLSS.day was obtained at F/M of 1.5 g COD /g MLSS.d. Whereas, the BMBR system was operated with a biomass concentration of up to 25 g MLSS/L, resulting in maximum COD removal rate of 0.32 kg COD /kg MLSS.day at F/M ratio of 0.4. In comparison to BMBR, YMBR could obtain higher COD removal rate at higher organic loading, indicating the potential of a yeast reactor system to treat high salinity wastewater containing high organic concentration.</jats:p> <jats:p>Transmembrane pressure in BMBR was progressively increased from 2 to 60 kPa after 12 d, 6 d and 2 d at a hydraulic retention time (HRT) of 14 h, 9 h and 4 h, with average biomass concentration of 6.1, 15 and 20 g MLSS/L, respectively. Whereas the transmembrane pressure in YMBR has increased from 2 to 60 kPa only after 76 days of operation, with an average biomass concentration of 12 MLSS/L and an operating HRT range of 5-32 h.</jats:p>

Saufie S, Estim A, Shaleh SRM et al.

International Journal of Water and Wastewater Treatment • 0

<jats:p>Effluents from aquaculture systems contain large volumes of chemical substances and microbial load such as polychlorinated biphenyls and antibiotics that are often used to control infection and pathogenic bacteria originating from feed or water. These substances, if discharged, create pollution in the aquatic environment. Mitigating this problem requires implementing appropriate treatment methods. This study investigated the efficiency of uptake of nutrients in the wastewater and reduction of microbial pollution by chitosan. This product is a linear polysaccharide composed of β-linked D-glucosamine and N-acetyl-D-glucosamine and can be extracted from the shells of shrimps, lobsters, crabs and other crustaceans that are discarded in bulk quantities by seafood restaurants. The performance of laboratory-produced chitosan (S1) which was prepared from shells of Pacific white leg shrimp (Litopenaeus vannamei) was compared with that of the commercial grade chitosan (S2). While the latter was more effective in nitrogen and phosphorus removal and reduction of total faecal coliform, the two products were comparable in the uptake of minerals from the effluents from a tilapia culture system. The results showed that S1 and S2 adsorbed the nutrients from aquaculture effluents, especially ammonia (NH4 + ), nitrite (NO2 - ), nitrate (NO3 - ) and phosphate (PO4 3-). However, differences were evident in terms of the efficiency of their removal and duration of treatment required for the purpose. In this respect, S2 performed better. Moreover, the anti-bacterial activity of S2 was higher than that of S1, and this appeared to be linked to differences in surface features of the two products. The chitosan extracted from shrimp waste and processed locally provides a low-cost solution to the environmental problems caused by aquaculture effluents.</jats:p>

Hélène Percherancier, Bernadette Volat, Bernard Montuelle

Water Science and Technology • 1996

<jats:p>A simple procedure of batch experiments is described allowing the determination of the Biodegradable Dissolved Organic Carbon (BDOC) content of different effluent outfalls from wastewater treatment plants. The bioassay is based on the DOC reduction of treated wastewater samples inoculated with natural consortia of bacteria taken from river sediments or aquarium filters. This test allows routine determination of BDOC within a short period of time (less than 8 days). BDOC represents a still significant proportion of the treated effluent DOC: from 50% to about 70%, depending on the effluent. The origin of bacterial inocula have no influence on these proportions, but are the main parameter for the rate of biodegradation. Testing the biodegradability at 10°C and 20°C appears to be significant as it influences biodegradation processes and must be done for a complete ecological evaluation of the biodegradability of wastewater treatment plant effluents.</jats:p>

Shashirekha Viswanaathan, Pitchurajan Krishna Perumal, Seshadri Sundaram

Sustainability • 0

<jats:p>Increasing concentrations of carbon dioxide (CO2), one of the important greenhouse gases, due to combustion of fossil fuels, particularly burning coal, have become the major cause for global warming. As a consequence, many research programs on CO2 management (capture, storage, and sequestration) are being highlighted. Biological sequestration of CO2 by algae is gaining importance, as it makes use of the photosynthetic capability of these aquatic species to efficiently capture CO2 emitted from various industries and converting it into algal biomass as well as a wide range of metabolites such as polysaccharides, amino acids, fatty acids, pigments, and vitamins. In addition, their ability to thrive in rugged conditions such as seawater, contaminated lakes, and even in certain industrial wastewaters containing high organic and inorganic nutrients loads, has attracted the attention of researchers to integrate carbon capture and wastewater treatment. Algae offer a simple solution to tertiary treatments due to their nutrient removal efficiency, particularly inorganic nitrogen and phosphorus uptake. The algal–bacterial energy nexus is an important strategy capable of removing pollutants from wastewater in a synergistic manner. This review article highlights the mechanism involved in biological fixation of CO2 by microalgae, their cultivation systems, factors influencing algal cultivation in wastewater and CO2 uptake, the effect of co-cultivation of algae and bacteria in wastewater treatment systems, and challenges and opportunities.</jats:p>

K. K. Chin, S. L. Ong, L. H. Poh et al.

Water Science and Technology • 1996

<jats:p>Commercially available bacterial products were used in enhancing biodegradation of monoaromatic hydrocarbons in an attached-growth bioreactor and the treatment of wastewaters containing high concentration levels of organic wastes. For the augmented attached growth system empty bed hydraulic retention times (EBHRT) of 1.9 hours to 11.6 hours were run. Results showed that at 11.6 hour EBHRT 80% removal of 10.8 mg/L feed benzene, 96.8% removal of 8.1 mg/L feed toluene and 12.7% removal of 6.1 mg/L feed xylene were achieved. In the treatment of high strength sewage, significant removal of COD, BOD and oil and grease was observed over a 4 month trial run period.</jats:p>

M. Garcia, E. Bécares

Water Science and Technology • 1997

<jats:p>A comparative study on the removal of several pathogenic bacteria and their indicators was carried out at three natural wastewater treatment systems: stabilisation pond, high-rate algal pond and a free-water macrophyte system, retention times being 24, 5 and 3 days respectively. The macrophyte system showed higher removal efficiency for most of the groups, followed by stabilisation pond and high rate algal pond. All systems showed their highest efficiencies in the reduction of total coliforms, ranging from 98.68% for the stabilisation pond to 99.48% for the macrophyte process. Highly significant differences were found between the systems for bifidobacteria, C. perfringens and total coliforms removal. Pathogens and their indicators showed a different behaviour in their daily removal rate depending on the treatment plant.</jats:p>

V. Tare, P.C. Sabumon

Water Quality Research Journal • 1995

<jats:title>Abstract</jats:title> <jats:p>This investigation attempted to advance the state of the art of the process which utilizes the symbiotic relationship between the sulfate-reducing bacteria (SRB) and sulfide oxidizing bacteria (SOB) for degradation of organic matter present in wastewater. Major emphasis has been on the development of the desired microbial system without any external seed and comparative evaluation of the two types of multistage reversing flow bioreactor (MRB) systems. Biological vessels (BVs) in the MRB systems simulate conditions which correspond to configurations described as upflow sludge blanket and stationary fixed film. Two bench-scale models – one designed to achieve self granulation of sludge (SGS), and the second designed to promote growth of SRB/SOB on additional nonreactive surface – were set up and operated over a period of 4 months. Domestic wastewater supplemented with organic matter from sugar cane molasses was used as feed to develop the desired microbial population. Several visual and microscopic observations confirmed the presence of a significant number of SRB and SOB in all the biological vessels. Results indicated that it is possible to develop SGS and a microbial population of SRB and SOB which could attach to the nonreactive surface without any external seeding. Domestic wastewater could serve as a source of these organisms. Immobilized growth conditions and suspended growth conditions in BVs yield similar results in terms of organic matter utilization. The empirical formula for MRB biomass can be expressed as C11O12H36N5S.</jats:p>

Elena Diaz, Victor Monsalvo, Jose Palomar et al.

Encyclopedia of Inorganic and Bioinorganic Chemistry • 0

<jats:title>Abstract</jats:title> <jats:p>Ionic liquids (ILs) are probably the kind of chemical compounds that have been most intensively investigated in the past 10 years. The potential applications of ILs cover practically all disciplines of chemistry, having received particular attention in separation processes, catalysis, electrochemistry, nanotechnology, and material science. This increasing use promotes the synthesis and application of the new IL compounds at larger scales. As a consequence, a parallel effort has been made by the scientific community to evaluate the potential environmental hazards of ILs. With equal focus, several researches have also made relevant progress in the development of effective treatments to recover or remove ILs from wastewaters and soils. Certainly, the current state of art in the field of ILs results from the cooperative and multidisciplinary work of experts from different scientific fields. In this work, the toxicity and biodegradability of ILs have been revised from the point of view of environmental engineers, centering the analysis on the expected need of managing ILs in a wastewater treatment plant (WWTP). For this purpose, the available standard tests and other methods to evaluate the toxicity of potential xenobiotic compounds are summarized. An overview of the reported toxicities of ILs toward different assays is presented, with particular emphasis in the available guidelines for designing ILs with low toxicity. The standardized tests for determining the biodegradability of xenobiotics are also collected and described. Lastly, the biodegradation behavior of ILs have been summarized, as evidenced in the bibliography, depending on their structural features and the biological systems used in the bioassays. Preliminary analysis, focused on relevant aspects on the toxicity and biodegradability of ILs, was performed in our laboratory using activated sludge. The main aim is to provide useful guidelines for the future development of biological processes for treating wastewater contaminated with ILs in a WWTP.</jats:p>

Luboš Stříteský, Radka Pešoutová, Petr Hlavínek

Water Science and Technology • 2015

<jats:p>This paper deals with biological treatment of malt house wastewater using algal-bacterial flocs. During three months of testing, optimisation of growth conditions and biomass separation leads to maximisation of biomass production, improved flocs settleability and increased pollutant removal efficiency while maintaining low energy demand. At a high food to microorganism ratio (0.16 to 0.29 kg BOD5 kg−1 TSS d−1), the biological oxygen demand (BOD5), chemical oxygen demand (CODCr), total phosphorus (Ptot) and total suspended solids (TSS) removal efficiencies were all higher than 90%. At a food to microorganism ratio of 0.06 kg BOD5 kg−1 TSS d−1, BOD5, CODCr, total nitrogen (Ntot), Ptot and TSS removal efficiencies of 99.5%, 97.6%, 91.5%, 97.8% and 98.4%, respectively, were achieved. The study also proved a strong dependence of removal efficiencies on solar radiation. The results suggest the algae-bacteria system is suitable for treatment of similar wastewater in locations with available land and sufficient solar radiation and temperature during the whole year.</jats:p>

J. B. Carberry, R. W. Greene

Water Science and Technology • 1992

<jats:p>A computer model is presented for an innovative wastewater treatment process known as the Algae-Bacterial-Clay Treatment (ABCT) system. In this process the photosynthetic production of dissolved oxygen by algae supports the bacterial breakdown of organic matter in wastewater. Clay is added to the plug flow reactor to dampen input BOD variation. The model was developed to gain an improved understanding of transient behavior of dissolved oxygen and pH in the treatment reactor during typical operation.</jats:p> <jats:p>The model consists of five nonlinear ordinary differential equations describing the time rate of change of algae mass, bacterial mass, organic substrate, dissolved oxygen, and dissolved carbon dioxide. A fourth-order Runge-Kutta integration technique was used to predict system response at discrete time steps. The pH variation expected from changes in dissolved carbon dioxide was based upon presumptions that the system is buffered by the carbonic acid system, and that alkalinity does not change appreciably during the course of time. These assumptions were confirmed by experimental results.</jats:p> <jats:p>The model successfully predicted diurnal fluctuations in dissolved oxygen, carbon dioxide, and pH in the ABCT process. The model predicted that algae will supply sufficient oxygen during sunny and partly sunny days to eliminate the need for continuous mechanical aeration. This feature should result in significant cost savings over conventional secondary wastewater treatment schemes. Surplus dissolved oxygen produced by algae during the day should be completely depleted at night due to bacterial respiration. This lack of oxygen, in turn, resulted in reduced substrate utilization and potential effluent discharge violations. Mechanical aeration during the night might be one possible remedial strategy. Despite its dynamic behavior, the ABCT process would be a viable and potentially cost efficient wastewater treatment strategy.</jats:p>

Fuad Ameen

Biology • 0

<jats:p>Environmental pollutants such as toxic heavy metals and oxygen-demanding solids are generated by leather manufacturing. In most tanneries, wastewaters are treated with physico-chemical methods but overly high levels of pollutants remain in surface waters. The efficiency of tanning wastewater treatment with conventional techniques was evaluated in four tanneries in Saudi Arabia. It was observed that the wastewaters contained high amounts of pollutants, needing further treatment. We isolated microorganisms from the wastewaters and carried out experiments to treat the effluents with different bacteria, fungi, and their consortia. We hypothesized that a consortium of microorganisms is more efficient than the single microorganisms in the consortium. The efficiency of five single bacterial and five fungal species from different genera was tested. In a consortium experiment, the efficiency of nine bacterial–fungal consortia was studied. The bacterium Corynebacterium glutamicum and the fungus Acremonium sp. were the most efficient in the single-microbe treatment. In the consortium treatment, the consortium of these two was the most efficient at treating the effluent. The factory wastewater treatment reduced total dissolved solids (TDS) from 1885 mg/L to 880 mg/L. C. glutamicum treatment reduced TDS to 150 mg/L and Acremonium sp. to 140 mg/L. The consortium of these two reduced TDS further to 80 mg/L. Moreover, the factory treatment reduced BOD from 943 mg/L to 440 mg/L, C. glutamicum to 75 mg/L, and Acremonium sp. 70 mg/L. The consortium reduced BOD further to 20 mg/L. The total heavy-metal concentration (Cd, Cr, Cu, Mn, and Pb) was reduced by the factory treatment from 43 μg/L to 26 μg/L and by the consortium to 0.2 μg/L. The collagen concentration that was studied using hydroxyproline assay decreased from 120 mg/L to 39 mg/L. It was shown that the consortium of the bacterium C. glutamicum and the fungus Acremonium sp. was more efficient in reducing the pollutants than the single species. The consortium reduced almost all parameters to below the environmental regulation limit for wastewater discharge to the environment in Saudi Arabia. The consortium should be studied further as an additional treatment to the existing conventional tannery wastewater treatments.</jats:p>

Bahareh Pirzadeh

Wastewater Treatment • 0

<jats:p>Water is a valuable material. Water used to dispose of nature or enter the consumption cycle requires disinfection and purification to conserve water resources as well as to provide drinking water. Different processes are carried out on the water to increase water quality as much as possible. In general, the filtration process can be divided into two general categories. In the first process, harmful substances are removed from the water. In the second group, the processes are specifically designed to improve the quality and control parameters such as the pH value. The stages of water purification can be divided into different steps more in detail, which physical purification is one of these steps and has been discussed in this chapter.</jats:p>

Franck Michael ZAHUI, Jean-Marie Pétémanagnan Ouattara, Mahamadou Kamagaté et al.

• 0

<title>Abstract</title> <p>Bacteria are frequently studied in constructed wetlands (CWs) due to their effective involvement in pollutants purification processes. In this study, aerobic, anaerobic and total bacteria densities and their vertical distribution profile within pilot-scale vertical flow CWs planted with different plant species were investigated. Five beds were planted in monoculture with <italic>Andropogon gayanus, Chrysopogon zizanioides, Echinochloa pyramidalis, Pennisetum purpureum</italic> and <italic>Tripsacum laxum</italic>, and one unplanted bed was used as control. At the end of the treatment trial, bacteria were collected by taking cores of sediment samples at the corners and the center of each bed following six layers in the vertical profile. In fact, the presence of plants on CWs improved the bacterial density and removal efficiencies in the system, with yields from 5.9 to 24.1% regardless the pollutant. However, few anaerobic bacteria were obtained in the different wetlands, and unable to reduce NO₃⁻, excluding for beds planted with <italic>T. laxum</italic> and <italic>P. purpureum</italic>. Besides, the number of aerobic bacteria determined decreased (<italic>i.e.</italic>, 17.4 10⁶ to 0.1 10⁶ CFU.g^− 1), while that of anaerobic bacteria increased (<italic>i.e.</italic>, 0.1 10⁶ to 2.1 10⁶ CFU.g^− 1) from the upper to the bottom layers in the planted beds. Otherwise, anaerobic bacteria were more abundant in the control than in planted beds. Then, total bacteria were dominated by aerobic bacteria, and decreased from surface toward the bottom. As <italic>P purpureum</italic> promotes the best performance, CWs with this type of plant could be a cost-effective alternative method of treating wastewater.</p>

J. Han, L. Y. Wang, B. Y. Cai

Water Science and Technology • 2013

<jats:p>The bacterial diversity of an antibiotic industrial wastewater treatment system was analyzed to provide the information required for further optimization of this process and for identification of bacterial strains that perform improved degradation of antibiotic industrial wastewater. The total bacterial DNA of samples collected at three stages (aeration, precipitation, and idle) during the sequencing batch reactor (SBR) process were analyzed by polymerase chain reaction–denaturing gradient gel electrophoresis (PCR-DGGE) of the 16 s rDNA V3 regions. Community analysis was conducted in terms of the richness value (S), the dominance degree and the Shannon–Wiener diversity index (H). Rich bacterial diversity was apparent in the aeration stage of the SBR process, and the number of bands in the aeration stage was more abundant than that in the precipitation and idle stages. The DGGE analysis showed 15 bands, six of which were uncultured bacteria, and included one anaerobic and five aerobic bacteria. The microbial community in the aeration stage was the most complex of the whole SBR process, while the dominant bacteria differed in each reaction stage. These results demonstrate the cyclical dynamic changes in the bacterial population during the SBR process for the treatment of antibiotic industrial wastewater.</jats:p>

K. Sankaran, Lakshmi Pisharody, G. Suriya Narayanan et al.

RSC Advances • 0

<p>Treatment of ADSW with culture rich in<italic>Pseudomonas</italic>sp. resulting benefits such as improved physico-chemical characteristics; biomass availability for energy generation; easy operation of subsequent downstream units of effluent treatment plant.</p>

A. Rada-Ariza, C. Lopez-Vazquez, N. P. Van der Steen et al.

Algal Systems for Resource Recovery from Waste and Wastewater • 2023

<jats:title>Abstract</jats:title> <jats:p>Nitrogen-rich wastewaters (10–400 mg N/L) are produced by municipal, industrial and agricultural wastes, including effluents from anaerobic treatment processes. These represent a risk to the environment due to the high nutrient concentrations (nitrogen and phosphorous), which can cause eutrophication of water bodies, deteriorating the quality of the ecosystems. As a solution, the nitrogen removal capacity of a novel bio-treatment system, the photo-activated sludge (PAS), composed of microalgae and bacteria consortia can be applied. Photobioreactors used for the simultaneous cultivation of microalgae and bacteria under sequencing batch conditions showed that microalgal–bacterial consortia can remove ammonium 50% faster than solely microalgal consortia. The increase in ammonium removal rates is due to the action of nitrifying bacteria, supplied with oxygen produced by the algae. The microalgal–bacterial system offers the possibility of reducing the hydraulic retention time, which can decrease the large area requirements often demanded by algal systems. The SRT is the main parameter to control the efficiency of the technology. The control of the suspended solids concentration, by adjusting the SRT, influences the light penetration within the reactor, which can limit or enhance the oxygen production of the algae. The photo-activated sludge system using microalgal–bacterial consortia is a sustainable treatment option for ammonium-rich wastewaters, providing clean effluents and opening reuse options for the biomass.</jats:p>

Donghan Kang, Keugtae Kim

Processes • 0

<jats:p>Algal–bacterial consortium is a promising technology, combined with wastewater treatment plants, because algae produce molecular oxygen for nitrification and organic removal and reduce carbon dioxide emissions. However, algal–bacterial consortia based on suspended growth require a relatively long hydraulic retention time (HRT) of 4 d to 6 d for removal of organic matter and nutrients. For the algal–bacterial consortia in a photobioreactor (PBR) containing a moving bed, the organic matter and nutrient removal and the community structure of algal–bacterial consortia were investigated to determine the performance under a relatively short HRT of 2.5 d. Moving media containing algal–bacterial consortia enhanced the photosynthetic oxygen concentration (0.2 mg dissolved oxygen (DO)·L−1 to 5.9 mg DO·L−1), biochemical oxygen demand removal (88.0% to 97.2%), ammoniacal nitrogen removal (33.8% to 95.3%), total nitrogen removal (61.6% to 87.7%), total phosphate removal (66.4% to 88.7%), algal growth (149.3 mg algae·L−1 to 285.4 mg algae·L−1), and settleability (algae removal efficiency of 20.6% to 71.2%) compared with those of a PBR without moving media (SPBR). Although biomass uptake was the main mechanism for nutrient removal in the SPBR, both biomass uptake and denitrification were the main mechanisms in the PBR with moving media (MBPBR). The bacterial community also changed under the moving media condition. This study shows that moving media might be an essential parameter for PBRs with a short HRT to enhance nutrient removal and settleability.</jats:p>

Yongfeng Wang, Qiang He

Encyclopedia of Water • 0

<jats:title>Abstract</jats:title><jats:p>Anaerobic treatment technology, represented by anaerobic digestion, is an important microbial process for wastewater treatment. Anaerobic treatment is superior to aerobic processes with reduced energy demand, lower excess sludge production, and the generation of methane as a source of renewable energy. In anaerobic treatment, organic waste is converted into methane and carbon dioxide via four successive steps – hydrolysis, acidogenesis, acetogenesis, and methanogenesis. The interactions between microbial populations have major impacts on the performance of anaerobic treatment processes. The competition between populations of<jats:italic>Firmicutes</jats:italic>and<jats:italic>Bacteroidetes</jats:italic>is closely correlated to process stability. Similarly, the competition between two acetoclastic methanogens with distinct kinetics characteristics, i.e.<jats:italic>Methanosaeta</jats:italic>and<jats:italic>Methanosarcina</jats:italic>, is linked to changes in the level of acetate as a metabolic intermediate associated with process perturbations. Further, syntrophic interactions between the<jats:italic>Bacteria</jats:italic>and<jats:italic>Archaea</jats:italic>play central roles in maintaining process balance. Indeed, syntrophic interactions are required for the conversion of diverse intermediates and substrates, including organic acids, alcohols, and aromatics, in anaerobic treatment. The microbial interactions underlying anaerobic treatment are critical to process performance. The availability of new tools, such as high‐throughput sequencing technologies, makes it possible to gain further understanding of population interactions at the microbiome level in order to develop more robust anaerobic treatment processes for broader applications as sustainable alternatives.</jats:p>

Victor Odhiambo Shikuku, Wilfrida N. Nyairo, Chrispin O. Kowenje

Advances in Environmental Engineering and Green Technologies • 2019

<jats:p>Biochars have been extensively applied in soil remediation, carbon sequestration, and in climate change mitigation. However, in recent years, there has been a significant increase in biochar research in water treatment due to their stupendous adsorptive properties for various contaminants. This is attributed to their large surface areas, pore structures, chemical compositions, and low capital costs involved making them suitable candidates for replacing activated carbons. This chapter discusses the preparation methods and properties of biochars and their removal efficacy for organic contaminants and microbial control. Factors affecting adsorption and the mechanisms of adsorption of organic pollutants on biochars are also concisely discussed. Biochars present environmentally benign and low-cost adsorbents for removal of both organic pollutants and microbial control for wastewater purification systems.</jats:p>

Sania Sahreen, Hamid Mukhtar

Microbial Bioremediation and Multiomics Technologies for Sustainable Development • 2024

<jats:p>Water pollution is continuously on the rise due to industrialization, rapid urbanization, agricultural activities, and global economic development. Developing countries directly discharge 80% of their untreated water, including industrial effluents, into water bodies without prior treatment. Finding a cost-effective, efficient, and environmentally friendly solution for industrial wastewater treatment remains a challenge. Floating treatment wetlands (FTW) offer an effective and sustainable technology for water treatment. This chapter presents a comprehensive overview of FTW as a promising solution for industrial wastewater treatment. The chapter begins by emphasizing the importance of sustainable industrial wastewater treatment and introduces FTW as a viable approach. Next, FTW classification, principal components, and basic structural and design considerations are discussed in detail. The chapter further addresses the significance and working mechanism of plant–bacteria partnership in wastewater treatment as crucial aspects of FTW. Additionally, FTW as sustainable industrial wastewater management tools are also discussed through supporting case studies. Lastly, care, maintenance, and associated challenges in FTW implementation for wastewater treatment and enhancement strategies to overcome these challenges were briefed. In conclusion, FTW present a valuable opportunity for transforming industrial wastewater treatment into a more ecologically balanced and sustainable practice.</jats:p>

, Abimbola Motunrayo Enitan

• 0

<jats:p>Anaerobic digestion, a proven and highly efficient biological process for treating industrial wastewater and biogas generation is an underutilized technology in South Africa. Some of the industries that have on-site anaerobic reactors tend to face problems in operating these reactors due to poor understanding of the process and implementation of the technology. This has resulted in high pollutant loads in their final effluents and low energy recovery. In this study, an on-site full–scale upflow anaerobic sludge blanket (UASB) reactor treating brewery wastewater was extensively monitored in order to evaluate the efficiency in terms of effluent quality, biogas production and microbial structure. Furthermore, developed and adopted kinetic models were used to optimize the performance of the full–scale UASB reactor using a combined Pareto differential evolution (CPMDE) algorithm. A preliminary analysis of the raw wastewater has shown that the wastewater produced from the brewery industry was high in organic matter with a total chemical oxygen demand (COD) between 1096.41 to 8926.08 mg/L. The average removal efficiency of COD from the UASB reactor after treatment was 79% with a methane (CH4) production of 60-69% at temperature ranges of 28-32˚C and hydraulic retention time (HRT) of 12 h within the optimal pH range for anaerobic bacteria (6.6 and 7.3) under various organic loading rates. However, the results also showed an increase in total suspended solids (TSS), nitrogen (N2), ammonia (NH3) and orthophosphate concentrations when comparing the influent to the effluent, which indicated the necessity for further optimization of the reactor condition in order to reduce these effluent parameters to acceptable standards and to increase CH4 production. In order to optimize the process, a thorough understanding of microbial interaction was essential. A combination of different molecular techniques viz., fluorescence in–situ hybridization (FISH), polymerase chain reaction (PCR) and quantitative real-time PCR (QPCR) were employed to understand the microbial community structure of the granular sludge samples using species specific primers and probes. The results revealed that the dominance of diverse groups of eubacteria belonging to phyla Proteobacteria, Firmicutes and Chloroflexi and an uncultured candidate division WS6 with four different orders of methanogenic Archaea viz., Methanomicrobiales, Methanococcales, Methanobacteriales and Methanosarcinales belonging to hydrogenotrophic and aceticlastic methanogens were within the reactor samples. Quantification of the 16S rDNA copies of eubacteria and methanogenic Archaea using species-specific primers further confirmed the spatial distribution of these microorganisms within the different compartments of the reactor where, the upper compartments were dominated by eubacteria and the lower compartments by methanogenic Archaea. The concentration of Archaea per nanogram of DNA was much higher (96.28%) than eubacteria (3.78%) in lower compartments, while, the eubacteria concentration increased to 98.34% in upper compartments with a decrease in Archaea quantity (1.66%). A modified kinetic methane generation model (MMGM) was developed on the basis of mass balance principles with respect to substrate (COD) degradation and the endogenous decay rate to predict CH4 production efficiency of the reactor. Furthermore, a Stover–Kincannon kinetic model was adopted with the aim of predicting the final effluent quality in terms of COD concentration and model coefficients were determined using the data collected from the full–scale reactor. Thereafter, a model-based multi-objective optimization was carried out using the CPMDE algorithm with three–objective functions namely; maximization of volumetric CH4 production rate; minimization of effluent substrate concentration and minimization of biomass washout, in order to increase the overall efficiency of the UASB reactor. Important decision variables and constraints related to the process were set for the optimization. A set of non-dominated solutions with high CH4 production rates of between 2.78 and 5.06 L CH4/g COD/day at low biomass washout concentrations were obtained at almost constant solution for the effluent COD concentration. A high COD removal efficiency (85-87%) at ~30-31˚C and 8-9 h HRT was obtained for the multi-objective optimization problem formulated. This study could significantly contribute towards optimization of a full–scale UASB reactor treating brewery wastewater for better effluent quality and biogas production. Knowledge on the activity and performance of microbial community present in the granular sludge taken from the full–scale UASB reactor would contribute significantly to future optimization strategies of the reactor. In addition, optimization using an evolutionary algorithm under different operational conditions would help to save both time and resources wasted in operating anaerobic bioreactors.</jats:p>

Ziyi Shi, Yanghao Jin, Tong Han et al.

Scientific Reports • 0

<jats:title>Abstract</jats:title><jats:p>Producing sustainable anode materials for lithium-ion batteries (LIBs) through catalytic graphitization of renewable biomass has gained significant attention. However, the technology is in its early stages due to the bio-graphite's comparatively low electrochemical performance in LIBs. This study aims to develop a process for producing LIB anode materials using a hybrid catalyst to enhance battery performance, along with readily available market biochar as the raw material. Results indicate that a trimetallic hybrid catalyst (Ni, Fe, and Mn in a 1:1:1 ratio) is superior to single or bimetallic catalysts in converting biochar to bio-graphite. The bio-graphite produced under this catalyst exhibits an 89.28% degree of graphitization and a 73.95% conversion rate. High-resolution transmission electron microscopy (HRTEM) reveals the dissolution–precipitation mechanism involved in catalytic graphitization. Electrochemical performance evaluation showed that the trimetallic hybrid catalyst yielded bio-graphite with better electrochemical performances than those obtained through single or bimetallic hybrid catalysts, including a good reversible capacity of about 293 mAh g<jats:sup>−1</jats:sup> at a current density of 20 mA/g and a stable cycle performance with a capacity retention of over 98% after 100 cycles. This study proves the synergistic efficacy of different metals in catalytic graphitization, impacting both graphite crystalline structure and electrochemical performance.</jats:p>

Jasreet Kaur, Amandeep Singh Pannu, Muhammad J. A. Shiddiky et al.

Advanced Sustainable Systems • 2024

<jats:title>Abstract</jats:title><jats:p>To address the fundamental challenge of resource sustainability and to effectively deal with issues pertaining to supply chain resilience, cost efficiency, environmental impact, and the ability to meet specific local needs; there is an urgent need for high‐grade battery anode materials produced locally from readily available raw materials. In this work, synthesis of high‐quality graphitic carbon (GH) derived from human hair is demonstrated using an in‐house engineered reactor based on Joule's Flash heating method. The GH is characterized using various techniques to examine its chemical composition, particle morphology, crystallinity, and demonstrate its usability as an anode material for lithium‐ion batteries. Fabricated coin cell with active material exhibits a gravimetric capacity of 320 mAh g<jats:sup>−1</jats:sup> at a current density of 30 mA g<jats:sup>−1</jats:sup> (equivalent to a C rate of ≈0.1C) over the 100 cycles. The in situ and ex situ studies using XRD, Raman, XPS, and UPS techniques conclude that during the initial charge cycle for GH, lithium ions diffused into the electrode during the resting period are effectively removed. This not only improves the lithium inventory to start with but also mitigates subsequent solvent degradation during solid electrolyte interphase (SEI) formation. Thus, these improvements ultimately enhance the capacity of the anode to 500mAh g<jats:sup>−1</jats:sup> at a current density of 20 mA g<jats:sup>−1</jats:sup>. The study offers the potential to initiate a new realm of research by redirecting the focus to a material once considered as mere waste.</jats:p>

Mario Culebras, Hugh Geaney, Anne Beaucamp et al.

ChemSusChem • 2019

<jats:title>Abstract</jats:title><jats:p>Development of cost‐effective and increasingly efficient sustainable materials for energy‐storage devices, such Li‐ion batteries, is of crucial future importance. Herein, the preparation of carbon nanofibres from biopolymer blends of lignin (byproduct from the paper and pulp industry) and polylactic acid (PLA) or a thermoplastic elastomeric polyurethane (TPU) is described. SEM analysis shows the evolving microstructural morphology after each processing step (electrospinning, stabilisation and carbonisation). Importantly, it is possible to tailor the nanofibre porosity by utilising miscibility/immiscibility rules between lignin and the polymer additive (PLA/TPU). PLA blends (immiscible) generate porous structures whereas miscible lignin/TPU blends are solid when carbonised. Electrodes produced from 50 % PLA blends have capacity values of 611 mAh g<jats:sup>−1</jats:sup> after 500 charge/discharge cycles, the highest reported to date for sustainable electrodes for Li‐ion batteries. Thus, this work will promote the development of lignocellulose waste materials as high‐performance energy‐storage materials.</jats:p>

Zhihan Gao, Bo Wang, Jinhua Liu et al.

Materials Research Express • 2023

<jats:title>Abstract</jats:title> <jats:p>Non-calcined petroleum coke can serve as an anode material for lithium-ion batteries (LIBs). Nevertheless, this method results in materials with insufficient conductivities and low Coulombic efficiencies during the initial cycle. To address these challenges, the usage of pre-baked carbon anodes as a material for anodes in LIBs is proposed in this study. The surface features of the pre-baked anode (i.e. wrinkle-like filaments) aid in reducing the volume expansion of the electrode during the lithium-ion insertion–removal process. Furthermore, the treatment increases the particle contact area, improving the conductivity of the pre-baked anode. At a current density of 3 A g<jats:sup>−1</jats:sup>, the pre-baked anode demonstrated an initial discharge capacity and a stable discharge capacity of 548.7 and 134.5 mAh g<jats:sup>−1</jats:sup>, respectively, after 100 cycles. The capacity of the anode (after 1000 cycles) consistently varies within a narrow range at a current density of 3 A g<jats:sup>−1</jats:sup>, indicating the stability of the electrode capacity over extended use. Therefore, this study provides valuable insights into exploring potential applications of pre-baked anode materials.</jats:p>

Wei He, Zihao Su, Meizhen Qu et al.

Chemistry – A European Journal • 2025

<jats:title>Abstract</jats:title><jats:p>Silicon (Si) is considered to be one of the most promising anode materials for next‐generation lithium‐ion batteries because of its abundant reserves, low discharge potential, and most importantly, its high theoretical specific capacity. However, the practical application of Si‐based anodes is mainly hindered by the low intrinsic conductivity of Si and the large volume change upon lithiation/de‐lithiation. In order to improve the electrochemical performance of Si‐based anodes, we prepared a composite material consisting of Si nanoparticles (NPs) and coconut silk bio‐carbon (CSC) skeleton. The porous carbon skeleton derived from coconut silk with natural through‐holes and ample micropores on the wall, which was used as the carrier of Si NPs. The continuous through‐holes and well‐distributed oxygen‐containing functional groups of the CSC provided sufficient space and abundant adsorption active sites for Si NPs, what‘s more, the good dispersion of Si NPs in the through‐holes increased their contact with the surrounding carbon materials, which was conducive to electron transport. Meanwhile, the pore structure also provided buffer space for the volume expansion of Si. The rich oxygen‐containing functional groups can form a certain chemical force with silicon particles, and further stabilize the nano silicon particles. Hence, the CSC/Si electrode revealed an excellent capacity retention of 82.8 % at 1 A g<jats:sup>−1</jats:sup> after 100 cycles. This study provides a simple universal high‐throughput method to obtain anode materials with outstanding electrochemical properties and promotes the further development of Si/C composites.</jats:p>

Yan Qiao, Xiao-Shuai Wu, Cai-Xia Ma et al.

RSC Adv. • 0

<p>A three-dimensional graphene/nickel composite electrode with a hierarchical porous structure is developed to simultaneously boost the bio- and electro-catalysis for high-performance microbial fuel cells.</p>

Shantanu Bhattacharyya, Srikanta Moharana, Santosh K Satpathy et al.

Journal of Advanced Zoology • 0

<jats:p>Bio-photovoltaics (BPV) is sustainable energy production technology that utilize photosynthetic organisms and convert it into electricity. This Study has been carried out to study the photosynthetic efficiency of three microalgae on a Reduced Graphene Oxide (RGO) anode surface. RGO, with its exceptional electrical conductivity and large surface area, presents an attractive platform for enhancing the performance of BPV systems. The work aims to investigate the combined effect of microalgae and RGO anodes for use in BPV technology. RGO was synthesized and characterized on which Chlorella vulgaris, Gloeocapsa and Synechocystis were allowed to grow. A model BPV system was assembled, incorporating the microalgae and cyanobacteria as photoactive agents and RGO as the anode surface. The system was subjected to different experimental condition and photosynthetic efficiency, current generation, and power output were collected and analysed. Results demonstrated a significant improvement in the photosynthetic activity of microalgae when cultured on the RGO anode surface. Chlorella Shows maximum Efficiency in terms of growth and current generation. Statistical analysis confirmed the reliability and significance of these findings. Our finding bridges a crucial knowledge gap in the field of BPV, highlighting the potential of microalgae-RGO systems for cleaner energy production.</jats:p>

Aisyah Nadhirah Juhari, Muhd Syazwan Sharani, Wan Ramli Wan Daud et al.

Sains Malaysiana • 2020

<jats:p>A biophotovoltaic cell (BPV) is an electrobiochemical system that utilises a photosynthetic microorganism for instance is algae to trap sunlight energy and convert it into electricity. In this study, a local algae strain, UKM2 Chlorella sp. was grown in a BPV under different trophic conditions and light wavelengths. Once the acclimatisation phase succeeded, and biofilm formed, power generation by UKM2 algae at the autotrophic mode in synthetic Bold’s Basal media (BBM) under white, blue and red lights were tested. Polarisation and power curves were generated at these different conditions to study the bioelectrochemical performance of the system. Later, the condition switched to algal mixotrophic nutritional mode, with palm oil mill effluent (POME) as substrate. Maximum power generation obtained when using UKM2 in BBM under red light where a power density of 1.19 ± 0.16 W/m3 was obtained at 25.74 ± 3.89 A/m3 current density, while the open circuit voltage OCV reached 226.08 ± 8.71 mV. UKM2 in POME under blue light recorded maximum power density of 0.85 ± 0.18 W/m3 at current density of 16.75 ± 3.54 A/m3, while the OCV reached 214.05 ± 23.82 mV. Chemical oxygen demand (COD) removal reached an efficiency of 35.93%, indicating the ability of wastewater treatment and electricity generation in BPV at the same time.</jats:p>

Sadananda Muduli, Rupan Das Chakraborty, Pramod Verma et al.

Journal of The Electrochemical Society • 2022

<jats:p>Lead-carbon hybrid ultracapacitors (Pb-C HUC) are the solution to the sulfation issue of lead-acid batteries. The Pb-C HUCs are of much interest due to the aqueous system with longer cycle life and higher power density. Here, honeycomb structured porous activated carbons with 1790 m<jats:sup>2</jats:sup> g<jats:sup>−1</jats:sup> of surface area were synthesized from Carica papaya biowaste by chemical treatment followed by carbonization at 800 °C (PAC-800). PAC-800 composite electrode delivers a specific capacitance of 250 F g<jats:sup>−1</jats:sup> at 1 Ag<jats:sup>−1</jats:sup> and has 10000 stable cycle life in 4.5 M H<jats:sub>2</jats:sub>SO<jats:sub>4</jats:sub>. Further, a kinetic study of the PAC-800 electrode illustrates that at 2 mV s<jats:sup>−1</jats:sup>, they show 61% of capacitive and 39% of pseudocapacitive charge storage. Pb-C HUCs fabricated using in situ activated PbO<jats:sub>2</jats:sub> sheet as cathode and PAC-800 composite electrode as anode delivers 390 F g<jats:sup>−1</jats:sup> at 1 A g<jats:sup>−1</jats:sup> and have 93% capacitance retention over 15000 cycles at 5 A g<jats:sup>−1</jats:sup>. Further, the current Pb-C HUC results are compared with commercially available high surface area (2484 m<jats:sup>2</jats:sup> g<jats:sup>−1</jats:sup>) carbons based Pb-C HUCs. This work illustrates an easy, scalable synthesis root for biowaste carbons and their electrochemical performance in Pb-C HUCs, which is on par with commercial high surface area carbons.</jats:p> <jats:p> <jats:inline-formula> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="jesac8eda-ga.jpg" xlink:type="simple"/> </jats:inline-formula> </jats:p>

Jiashen Tian, Ryan J. Milcarek

Journal of The Electrochemical Society • 2021

<jats:p>Siloxane, a common contaminant present in biogas, is known for adverse effects on cogeneration prime movers. In this study, the siloxane deposition products and mechanism in the solid oxide fuel cell nickel-yttria stabilized zirconia (Ni-YSZ) anode are investigated analytically and experimentally. An SOFC with Ni-YSZ anode and pure Ni/YSZ pellets were exposed to a simulated biogas-reformate fuel with octamethylcyclotetrasiloxane (D4) contamination at 750 °C. The electrochemical characterization results show that the SOFCs performance degradation caused by D4 contamination is irreversible. Morphology and XRD results illustrate that silicon and carbon deposition can both be detected in the anode and pellets. Graphite, SiC and SiO<jats:sub>2</jats:sub> are all possible products based on the results of XRD test. According to the formation of graphite and SiC, the new mechanism suggests that carbon is also an essential factor in siloxane contamination of Ni-YSZ anodes besides silicon, which can be explained by the catalytic and electrochemical analysis.</jats:p>

Koichi Kasahara, Hirokazu Ishitobi, Shota Yamamori et al.

Journal of Electrochemical Energy Conversion and Storage • 2016

<jats:p>By modifying the carbon electrode with a yeast extract (YE) using a support material (SM), a complete bio-anode was established without adding any extrinsic enzymes and mediators in a glucose–air fuel cell. The yeast extract was mixed into a paste with carbon black and an SM, i.e., glutaraldehyde (GA), TritonX-100, polyethyleneglycol, chitosan, or agarose. Chitosan was the best support, producing lower overpotentials and a good stability. Optimization of the paste composition and its loading were carried out for the bio-anode of a glucose–air fuel cell. The fuel cell generated a power of 33 μW cm−2 at 333 K with an aqueous glucose solution without adding any extrinsic enzymes and mediators. It showed about 70% of the initial power output at a stable condition. The bio-anode is expected to be used for energy recovery from hot wastewater-containing glucose.</jats:p>