Additional Carbon Source Research Articles

MOFs-derived porous carbon materials for gas adsorption and separation

The adsorption and separation of gases are important for mitigating the greenhouse effect, popularizing clean energy and treating volatile organic compounds (VOCs). Metal organic frameworks (MOFs) have been attracted broad attention due to their high specific surface area, adjustable pore structure and surface functionality. MOFs have been widely applied in gas adsorption and separation. The drawbacks of some MOFs are the high humidity sensitivity and poor thermal stability that hinder their industrial applications. Porous carbon materials possess high specific surface area, exceptional chemical and thermal stabilities. Porous carbon materials derived from MOFs as precursors not only overcome the shortcomings of some MOFs with poor water and thermal stabilities, but also retain the advantages of MOFs materials effectively. MOFs-derived porous carbon materials have good application prospects in gas adsorption and separation. This paper introduces the research status of MOFs-derived porous carbon materials, and focuses on their applications in the field of gas adsorption and separation. Synthesis methods for MOFs-derived porous carbon materials mainly include direct carbonization, carbonization with additional precursor and chemical activation. Specific surface area, pore size and surface functional groups of MOFs-derived porous carbon materials have great impact on their adsorption and separation performances for gases (carbon dioxide, hydrogen and volatile organic compounds). In general, MOFs-derived porous carbon materials with high surface area could exhibit excellent adsorption performance for CO2. And the pore size characteristics of MOFs-derived porous carbon materials play important roles in the adsorption capacity and diffusion rate of CO2. Nitrogen doping can improve CO2 adsorption capacities owing to Lewis acid-base interaction, electrostatic interaction and hydrogen bonding between the surface functional groups of MOFs-derived porous carbon materials and CO2. Furthermore, H2 storage is primarily determined by the narrow micropore, and chemical doping can effectively promote H2 storage of MOFs-derived porous carbon materials. In addition, VOCs adsorption is associated with the physiochemical characters of adsorbents (e.g., specific surface area, pore size, pore volume, surface chemical functional groups), properties of adsorbates (e.g., molecular weight, molecular structure, polarity, and boiling point) as well as the adsorption conditions (e.g., temperature and humidity). However, the researches on MOFs-derived porous carbon materials in gas adsorption and separation still face many challenges. (1) The pore structure, morphology and surface chemical properties of MOFs-derived porous carbon materials are directly affected by various factors, such as types of MOFs, types and amounts of additional carbon sources or additional nitrogen sources, carbonization temperature, time and atmosphere, types and ratios of activators, activation temperature and time, chemical doping and so on. (2) There are rare studies on the adsorption mechanism of MOF-derived porous carbon materials for various gases, the multi-component competitive adsorption mechanism, and the influence of environmental factors (such as environmental temperature and humidity) on the adsorption performance. (3) Environmental pollution will be caused during the chemical activation process of MOFs-derived porous carbon materials. At present, there are few reports on the recovery of pyrolysis gases and dispose of the generated waste during the activation process. (4) There is an urgent need to develop new synthetic methods for MOFs-derived porous carbon materials to achieve large-scale production. In a word, the related researches of MOFs-derived porous carbon materials can not only expand the application range of MOFs materials, but also promote the development of gas adsorption and separation. We believe that the application of MOFs-derived porous carbon materials in the field of gas adsorption and separation will make great breakthrough in the future.

Recycling industrial wastewater for improved carbohydrate-rich biomass production in a semi-continuous photobioreactor: Effect of hydraulic retention time

This study aimed to investigate a mixed microalgae culture's capacity to simultaneously remove nutrients and organic matter from industrial effluents while producing carbohydrate-rich biomass. A culture initially dominated by filamentous cyanobacteria Geitlerinema sp. was inoculated in a lab-scale stirred tank photobioreactor, operating at 10, 8, and 6 days hydraulic retention time (HRT). The results show that different HRT led to different inorganic carbon profiles and N:P ratios in the culture, influencing microbial changes, and carbohydrate content. Hence, higher N–NH4+ removal efficiencies were obtained at HRT of 10 d and decreased with decreasing HRT. Whereas, complete depletion of P-PO43- was achieved only at HRT of 8 d and 6 d. Also, the highest COD removal efficiency (60%) was achieved at 6 d of HRT. The maximum accumulation of carbohydrates was achieved at HRT of 8 d, which presented an N:P ratio of 22:1 and carbon availability, recording a constant carbohydrate content of 57% without any additional carbon source. Furthermore, this operational condition reached the best biomass production of 0.033 g L−1d−1 of easy-settling cyanobacteria dominated culture. According to the results, this process presents an alternative to recycling industrial effluents and, at the same time, grow valuable biomass, closing a loop for sustainable economy.

Analysis of phenanthrene degradation by Ascomycota fungi isolated from contaminated soil from Reynosa, Mexico.

Polycyclic aromatic hydrocarbons (PAHs) are organic compounds generated mainly by anthropogenic sources. They are considered toxic to mammals, since they have carcinogenic, mutagenic and genotoxic properties, among others. Although mycoremediation is an efficient, economical and eco-friendly technique for degrading PAHs, the fungal degradation potential of the phylum Ascomycota has not been widely studied. In this work, we evaluated different fungal strains from the polluted soil of 'La Escondida' lagoon in Reynosa, Mexico to know their potential to degrade phenanthrene (PHE). Forty-three soil isolates with the capacity to grow in the presence of PHE (0·1% w/v) were obtained. The fungi Aspergillus oryzae MF13 and Aspergillus flavipes QCS12 had the best potential to degrade PHE. Both fungi germinated and grew at PHE concentrations of up to 5000mgl-1 and degraded 235mgl-1 of PHE in 28days, with and without an additional carbon source. These characteristics indicate that A. oryzae MF13 and A. flavipes QCS12 could be promising organisms for the remediation of sites contaminated with PAHs and detoxification of recalcitrant xenobiotics.

Simultaneous removal of nitrate/nitrite and ammonia in a circular microbial electrolysis cell at low C/N ratios

In this study, the performance of a circular microbial electrolysis cell (MEC) system on removing NO3−-N/NO2−-N and NH4+-N at low C/N ratios was investigated. With the assistance of active bioelectrode, electron transportation and utilization efficiency between electron donor and acceptor was enhanced in MEC. High rate of nitrogen removal was observed in MEC at 0.2 V, which was 695.6 and 514.5 g-N/m3/d, respectively under COD/N = 2 and COD/N = 1. Without carbon source addition, the symbiotic activity of Anammox and electrochemical autotrophic denitrifiers were verified in MEC, in which the demand of NO2−-N for NH4+-N removal is calculated to be ∼1.3. Microbial community analysis revealed that the biocathode was enriched with autotrophic and heterotrophic nitrate/nitrite-reducing bacteria (e.g. 5.09 % Candidatus, 4.35 % Thauera and 3.34 % Comamonas), as well as the fermentative bacteria (e.g. 7.57 % Bacteroidetes). As heterotrophic denitrification, electroactive autotrophic denitrification, partial-denitrification and Anammox can coexist and collaborate in the MEC system, the strict nitritation to produce only nitrite toward Anammox can be avoided.

Efficacy of Probiotics and Bioflocs on the Production Performance of Tiger Shrimp Penaeus monodon and Pacific White Shrimp Litopenaeus vannamei during Polyculture Operation

Shrimp culture has been developed during the last three decades and the production of farmed shrimp reached its peak. However, the shrimp production was decreased all over the World including in Asian Countries because of the mass mortality due to the outbreak of several diseases predominantly White Spot Syndrome Virus (WSSV) which caused extensive economic damage to the shrimp culture industry. Various Polyculture technologies of shrimp with shellfish, finfish or seaweeds have been implemented to reduce economic damages by mass mortality of shrimp. The present study was conducted with Tiger shrimp Penaeus monodon and Pacific white shrimp Litopenaeus vannamei through Polyculture operation to determine optimum stocking ratios for induction of best performance and highest production rates. Initially, the experiments were conducted with different ratios and combinations of stocking densities 1:1, 2:1 and 1:2 ratios of Penaeus monodon and Litopenaeus vannamei with control group feed with commercial feed, the other group certain Probiotic bacteria such as Bacillus licheniformis and Lactobacillus rhamnosus added in feed, the third group both the Probiotic bacteria and the addition of external Carbon source from sugarcane molasses in the form of Bioflocs for 100 days. To ascertain further interaction of ratios influence, 20:10, 20:12, 20:15 ratios of stocking and Monoculture experiments were conducted. In both the experiments the Survival rate, Final body weights, Weight Gain, Feed conversion ratio, Specific growth rates, Average daily growth rates, Protein efficiency ratio, and Productivity rates were significantly different (P<0.05) in all the different treatments both for P. monodon and L. vannamei. From the results obtained 20:10 ratio of P. monodon and L. vannamei was considered as the best ratio of stocking, which yielded the highest production rates in all the Control, Probiotic added and both Probiotic & Biofloc added groups. The results obtained in the present study clearly demonstrate that the rearing of taxonomically similar species with optimum stocking ratios seems to improve the efficiency of shrimp farming and substantially increasing the production rates. So, this polyculture of P. monodon and L. vannamei can be considered as an alternative approach towards the establishment of sustainable shrimp farming activity which will yield good economic returns.

Butyrate can support PAOs but not GAOs in tropical climates

Glycogen accumulating organisms (GAOs) are thought to compete with polyphosphate accumulating organisms (PAOs) for the often-limiting carbon sources available in wastewater, deteriorating enhanced biological phosphorus removal (EBPR) performance at high temperatures. Fermentation liquids are often used to provide an additional carbon source supply in EBPR processes, where butyrate is known to be an important volatile fatty acid (VFA) produced in sludge fermentation. Nevertheless, the impact of butyrate on the PAO-GAO competition is not well understood especially at high temperature. The results of this study demonstrate that butyrate, as a supplemental or sole carbon source, could be promising for EBPR in tropical climates. When the carbon source was gradually changed from acetate to butyrate, a substantial PAO population was found under both conditions, despite a substantial shift in the abundance of Candidatus Accumulibacter phosphatis (decreased from 37.4% to 13.9%) to Rhodocyclaceae (increased from 2.0% to 14.5%), where both organisms likely played an important role in P-removal. Thus, a relatively stable P removal performance was realized throughout the whole operation period. Nevertheless, butyrate had a negative impact on GAOs. The biomass concentration and microbial diversity continually decreased in the GAO reactor, and Candidatus Competibacter phosphatis reduced from 27.3% to 6.2%, where the dominant population was replaced by Zoogloea. With the addition of butyrate as carbon source, the total amount of synthesized PHAs reduced in both PAO and GAO cultures and the composition of PHA was greatly changed. The presence of a novel PHA fraction (PHH) may disturb the microbial activity in the aerobic phase, where the GAO culture was more severely affected. Glycogen cycling also seemed to be limited in both reactors. This could reduce the GAO metabolism in both cultures and favor PAOs and P removal. Furthermore, the biomass growth rate of the PAO culture was higher than that of GAO when fed with butyrate, which also provides PAO a competitive advantage. All the above results indicate that butyrate could not be well metabolized by GAOs, but could provide PAOs a competitive advantage. Thus, mixed VFAs (i.e. acetate, propionate and butyrate) are likely to favor PAOs over GAOs in EBPR processes operated in warm climates, where the impact of substantial butyrate fractions represents an advantage towards successful process operation.

Effects of In Situ Graphitic Nanocarbon Coatings on Cycling Performance of Silicon-Flake-Based Anode of Lithium Ion Battery

We coated graphitic nanocarbons by thermal chemical vapor deposition (CVD) on silicon flakes recycled from the waste of silicon wafer manufacturing processes as an active material for the anode of lithium ion battery (LIB). Ferrocene contains both iron catalyst and carbon, while camphor serves as an additional carbon source. Water vapor promotes catalytic growth of nanocarbons, including carbon nanotubes (CNTs), carbon fibers (CFs), and carbon films made of graphitic carbon nanoparticles, at temperatures ranging from 650 to 850 °C. The container of silicon flakes rotates for uniform coatings on silicon flakes of about 100 nm thick and 800–1000 nm in lateral dimensions. Due to short CVD time, besides CNTs and CFs, surfaces of silicon flakes deposit with high-density graphitic nanoparticles, especially at a low temperature of 650 °C. Nanocarbon coatings were characterized by SEM, EDX, ESCA, and Raman spectroscopy. Half-cells were characterized by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and retention of capacity in discharge/charge cycling. Silicon-flake-based anode with nanocarbon coatings at both 650 and 850 °C exhibited capacity retention of 2000 mAh/g after 100 cycles at 0.1 C, without needing any conductivity enhancement material such as Super P.

The genetic determinants of 4-chloro-2-nitrophenol degradation in Cupriavidus sp. strain NyZ417

4-chloro-2-nitrophenol (4C2NP) is a typical chlorinated nitroaromatic pollutant and its environmental fate is of great concern due to its mutagenic and carcinogenic properties. So far, neither genes nor enzymes responsible for 4C2NP biodegradation have been elucidated. Here, a new 4C2NP degrader NyZ417 was isolated from the activated sludge collected from a wastewater treatment plant of China and identified as a member within Cupriavidus genus according to its 16S rRNA gene sequence analysis. Cupriavidus sp. strain NyZ417 utilized 4C2NP as the sole of nitrogen source for its growth in the presence of additional carbon source. The degradation of 4C2NP by strain NyZ417 was confirmed via an oxidative pathway and induced by substrate itself. For the elucidation of molecular mechanism of 4C2NP degradation in this newly isolated degrader, a monooxygenase encoding gene onpANyZ417 retrieved from its complete genome was confirmed to be involved in 4C2NP biotransformation. Resting cells expressing OnpANyZ417 depleted 4C2NP completely with stoichiometric formation of 4-chlorocatechol. This study not only elucidated a functional gene for 4C2NP degradation but also would lay a solid foundation for designing approaches for clean-up of 4C2NP residues in the environment.

A scalable approach for synthesizing olivine structured LiMn1−xCoxPO4/C high-voltage cathodes

Olivine based cathodes with a chemical formula of LiMn1−xMxPO4 (where M = Fe, Ni, Co…) are considered as a potential candidate with their viability of high voltage applications, improved stability against various battery components and ambient conditions. However, the technology for scaling up the material synthesis remains a challenge. Solution combustion method stood forward among the other synthesis methods since it is possible to synthesize large quantities of materials with improved homogeneity and repeatability. In this study, olivine based LiMn1−xCoxPO4@C cathode materials were synthesized by a modified solution combustion method (SC) using glycine as fuel source, and starch as an additional carbon source. X-ray diffraction characterization of all samples suggested a highly crystallized orthorhombic olivine structure. In addition, it confirmed that Co2+ substitutes proportionately the transition metal Mn2+ without structural changes. Electron microscopy and Raman results pointed out the nanometer sized particles with a limited agglomeration and very thin carbon coating was successfully done. Electrochemical results suggested that Co-doping can improves cycling and high-rate capability of the pristine LiMnPO4/C material. Among all doped samples, LiMn0.99Co0.01PO4/C exhibited the best rate capability and cycling stability and the highest initial discharge capacity of 157 mAhg−1 at C/20, with a remarkable coulombic efficiency of about 98.1%, which is higher compared to that of the pristine sample LiMnPO4/C (80.38%). As a potential impact; this work reveals structure–property-process relationships for developing high-voltage cathodes by SC method targeted the best performance.

Improving sewage sludge compost process and quality by carbon sources addition

In present study, the effects of carbon sources on compost process and quality were evaluated in the lab-scale sewage sludge (SS) composting. The composting experiments were performed for 32 days in 5 L reactors. The results showed that carbon sources could change the nitrogen conversion and improve the compost quality. Especially, the readily degradable carbon source could promote organic matter degradation, improve nitrogen conversion process and accelerate compost maturation. The addition of glucose and sucrose could increase dissolved organic carbon, CO2 emission, dehydrogenase activity, nitrification and germination index during the SS composting. That's because glucose and sucrose could be quickly used by microbes as energy and carbon source substance to increase activity of microbes and ammonia assimilation. What's more, the NH3 emission was reduced by 26.9% and 32.1% in glucose and sucrose treatments, respectively. Therefore, the addition of readily degradable carbon source could reduce NH3 emission and improve compost maturity in the SS composting.

Evaluation of the nutritional quality of edible tissues (muscle and hepatopancreas) of cultivated Procambarus clarkii using biofloc technology

A 60-day study was conducted to evaluate the growth performance, nutritional quality of edible tissues (muscle and hepatopancreas) of red swamp crayfish (Procambarus clarkii) cultivated using commercial diet feeding (diet group) and biofloc technology (biofloc group). The commercial diet used in the biofloc group was only 60 % of that in the diet group. Glucose and wheat bran were used as additional carbon sources in the biofloc group. The results showed bioflocs was characterized by sufficient protein content but lower lipid content, however, the growth performance of crayfish in the biofloc group were significantly better at the end of the experiment. Besides, the total lipid content in hepatopancreas of crayfish in the biofloc group was higher. Moreover, saturated fatty acid (STA) content in hepatopancreas and monounsaturated fatty acid (MUFA) content in muscle were higher in the biofloc group, while MUFA content in muscle was significantly lower. No significant difference was observed in total amino acid (TAA), essential amino acid (EAA) and essential amino acids index (EAAI) in muscle in both groups. In conclusion, crayfish could be better cultivated using biofloc technology. However, the lipid deficiency and nutritional imbalance of bioflocs would affect the lipid nutritional composition in edible tissues of crayfish.

Effects of different carbon sources on water quality, biofloc quality, and growth performance of Nile tilapia (Oreochromis niloticus) fingerlings in a heterotrophic culture system

The biofloc system is one of the novel sustainable aquaculture systems, and adding carbonaceous organic matter is the basis of the system. This study aimed to evaluate the effects of different carbon sources on water quality, biofloc composition, and growth performance of Nile tilapia (Oreochromis niloticus). In this study, one control group (no carbon source addition) and four biofloc treatments with molasses (TM), starch (TS), barley flour (TB), and corn (TC) addition with three replications were considered. Altogether, 160 Nile tilapia with an average weight of 1.7 g were stocked in each of the 300-l tanks (160 l of water volume). The results of water quality indicated that the lowest levels of dissolved oxygen (5.43 mg/l) and pH (7.28) were observed in the TS treatment, which showed a significant difference (P < 0.05) compared to other treatments. There was a significant difference among various treatments in nitrogen compounds and the total density of heterotrophic bacteria. Biochemical quality of biofloc was affected by various carbon sources. The highest levels of protein (31.09%), lipid (3.89%), and ash (32.79%) were observed in TB, TC, and TM treatments, respectively. The largest biofloc size was obtained in TS treatment. The lowest survival rate and the highest level of weight gain of Nile tilapia were observed in control group. In conclusion, the present study showed that different sources of carbon in the biofloc system have different effects on water quality, biochemical composition, and biofloc size produced in cultivation tanks.

Accumulation and decomposition of cyanobacteria and reed debris in eutrophic lakes and its potential co-metabolism effects

为探究富营养化浅水湖泊所富集的有机物对湖泊碳循环和水质的影响，本研究构建微宇宙系统，模拟蓝藻和芦苇碎屑单独分解及混合分解过程.通过测定各组上覆水营养盐浓度、有机质含量及结构的变化，揭示富营养化湖泊藻草残体混合分解过程中养分和有机碳的释放特征.结果表明，在实验0~88 h内，在添加相同的碳源条件下，蓝藻和芦苇混合处理组总碳（TC）释放量显著高于理论值，表明藻草碎屑混合分解存在共代谢效应.在培养初期，沉积物通过共代谢效应对水质产生了较大的影响，加速向水体中释放氮、磷物质.相较单独的植物分解，混合处理组中总氮（TN）、总磷（TP）的最大释放量分别提高了13.49%和26.84%；通过三维荧光光谱表征的类富里酸荧光强度变化也表明：较芦苇处理组，混合处理组中芦苇的分解速率更快.在培养开始后，各处理组均快速转变为厌氧状态，TC、TN、TP浓度随时间变化总体上呈先快速上升再逐渐平缓的趋势，分别在第228、108和324小时达最大值（372.4±2.98）、（138.45±2.97）和（7.95±1.11） mg/L.细菌特异性脂肪酸含量变化表明，将蓝藻碎屑添加到芦苇碎屑中，会增加芦苇碎屑中细菌的丰度，从而提高分解速率，激发共代谢效应.在全球气候变暖的背景下，随着富营养化湖泊藻类暴发频次增加，共代谢效应可能还会进一步加强，对富营养化湖泊水质将会持续产生影响.;In order to explore the effect of enriched organic matter in eutrophic shallow lakes on water quality and carbon cycle, in this study, we constructed a microcosm system to simulate the separate decomposition and mixed decomposition of cyanobacteria and reed debris. The changes of nutrient concentration, organic matter content and structure of the overlying water in each treatment were determined to reveal the release characteristics of nutrients and organic carbon during the mixed decomposition process of cyanobacteria and reed debris in eutrophic lakes. The results showed that the total carbon (TC) release of the mixed treatment was significantly higher than the theoretical value within 0-88 hours of the experiment under the same carbon source addition, indicating that there is a co-metabolism effect during the mixed decomposition of cyanobacteria and reed debris. In the initial stage of the cultivation, sediments accelerated the release of total nitrogen (TN) and total phosphorus (TP) to the overlying water and caused a significant impact on the water quality via the co-metabolism effect. Compared with the reed treatment, the maximal release of TN and TP in the mixed treatment increased by 13.49% and 26.84%, respectively. The change of fluorescence intensity of fulvic acid characterized by the three-dimensional fluorescence spectroscopy (EEMs) also showed that the decomposition rate of reed was faster in the mixed treatment group. At the beginning of cultivation, each treatment quickly turned into anaerobic state, and the concentration of TC, TN and TP displayed a trend of dramatical increase and then gradually flattened, with a maximum of (372.4±2.98), (138.45±2.97), and (7.95±1.11) mg/L at 228, 108 and 324 hours, respectively. The variations of bacterial specific fatty acid showed that the input of Microcystis detritus into Phragmites detritus increased the abundance of decomposing bacteria in Phragmites detritus, and accelerated the decomposition rates, resulting in the co-metabolism of Microcystis and Phragmites carbon. Under the background of global warming, with the increasing frequency of algae outbreaks in eutrophic lakes, the co-metabolism effect may be further strengthened, and the water quality of eutrophic lakes will be affected continuously.

Methanol addition after glucose depletion improves rPOXA 1B production under the pGap in P. pastoris X33: breaking the habit

The purpose of this study was to demonstrate that methanol addition after glucose depletion has a positive effect on improving rPOXA 1B production under the control of pGap in P. pastoris. Four different culture media (A, B, C and D) were used to culture P. pastoris X33/pGapZαA-LaccPost-Stop (clone 1), containing a previously optimized POXA 1B synthetic gene coding for P. ostreatus laccase, which after glucose depletion was supplemented or not with methanol. Enzyme activity in culture media without methanol (A, B, C and D) was influenced by media components, presenting activity of 1254.30 ± 182.44, 1373.70 ± 182.44, 1343.50 ± 40.30 and 8771.61 ± 218.79 U L−1, respectively. In contrast, the same culture media (A, B, C and D) with methanol addition 24 h after glucose depletion attained activity of 4280.43 ± 148.82, 3339.02 ± 64.36, 3569.39 ± 68.38 and 14,868.06 ± 461.58 U L−1 at 192 h, respectively, representing an increase of approximately 3.9-, 2.4-, 3.3- and 1.6-fold compared with culture media without methanol. Methanol supplementation had a greater impact on volumetric enzyme activity in comparison with biomass production. We demonstrated what was theoretically and biochemically expected: recombinant protein production under pGap control by methanol supplementation after glucose depletion was successful, as a feasible laboratory production strategy of sequential carbon source addition, breaking the habit of utilizing pGap with glucose.

Finger millet as a carbon source for biofloc, improved growth performance of Pangasianodon hypophthalmus (Sauvage, 1878) fingerlings

A 90-days experiment was conducted to investigate the effects of biofloc produced with different carbon sources on growth performances, survival and body indices of Pangasianodon hypophthalmus fingerlings (average body weight: 6.4±0.05 g). The different carbon sources used in the experiment employing biofloc technology (BFT) were BFT-T (tapioca), BFT-S (sorghum), BFT-PM (pearl millet), BFT-FM (finger millet) and clear water with no addition of carbon source was treated as control. At the end of the experiment, significantly (p&lt;0.05) higher weight gain (24.34±0.50 g), Specific growth rate, SGR (1.37±0.02% day-1); Feed efficiency ratio, FER (0.47±0.01); Protein efficiency ratio, PER (1.47±0.03) and lower Feed conversion ratio, FCR (2.12±0.03) were witnessed in the group where finger millet was used as a carbon source (BFTFM) and significantly lower responses were noticed in the control (CW). Results showed that there were no significantdifferences (p&gt;0.05) in hepatosomatic index and viscerosomatic index of fish between the different experimental groups. During the termination of the experiment, no mortality was seen among the different experimental groups. Based on the results acquired from this study, finger millet could be used as an ideal carbon source for biofloc to augment the growth and productivity of P. hypophthalmus under farming.

Synthesis of glycogen by Chlorobium limicola IMV K-8 while growth in wastewater

Due to the high content of organic compounds, the distillery wastewater can be a good substrate for the production of glycogen during cultivation of green photosynthetic bacteria. Green photosynthetic bacteria Chlorobium limicola IMV K-8 are producers of glycogen and show exoelectrogenic properties when grown alone or inside the co-culture with heterotrophic bacteria-exoelectrogens in wastewater of various origins. In our previous works it was found that due to the phototrophic growth of C. limicola IMV K-8 in the distillery wastewater significantly reduces the content of compounds of nitrogen, sulfur, Ca2+, Mg2+ and others. The study of the patterns of glycogen synthesis by green photosynthetic bacteria during growth in such an extreme environment as the wastewater of a distillery has prospects for the development of biotechnology for the production of this polysaccharide. The aim of the study was to investigate the glycogen content in C. limicola IMV K-8 cells under different growth conditions in the wastewater of the distillery. Bacteria were grown in the wastewater of the distillery under light (phototrophic growth) and without light exposure (heterotrophic growth). Bacterial cells grown on GSB medium under light (phototrophic growth) and without light (heterotrophic growth) exposure were used as controls. Glycogen content was determined at 7, 14, 21 and 30 days of growth by the glucose oxidase method. Glucose or glycogen in the wastewater of the distillery without the introduction of bacteria was not detected. It was found that the content of glycogen in cells of C. limicola IMV K-8 grown in the wastewater of the distillery, under light exposure increased from 3.8 % to 39.8 % of cells dry weight from the seventh to third day of growth during 30 days of cultivation and was 2 times higher the glycogen content of cells on GSB medium. It is assumed that the bacteria C. limicola IMV K-8 use available in the water sources of carbon and other compounds necessary for cell metabolism along with glycogen biosynthesis and bioremediation of wastewater. During C. limicola IMV K-8 growth in the darkness there is an assimilation of organic sources of carbon (acetate, pyruvate and probably organic compounds of wastewater), which allows cells to remain viable for 30 days without additional sources of carbon, nitrogen, etc., but significant glycogen synthesis does not occur. The glycogen formed under phototrophic conditions can be further a source of carbon or a substrate for electric current generation by exoelectrogenic bacteria.

Performance evaluation of biocatalytic and biostimulation approaches for the remediation of trace organic contaminants in municipal biosolids

Trace organic contaminants (TrOCs) in biosolids is creating potential threats for reuse of biosolids. Out of the tested 64 trace organic contaminants, seven pharmaceutically active compounds (PhACs), and three pesticides were detected in biosolids from a municipal wastewater treatment plant. This study encompasses the removal of TrOCs and improvement in the aerobic digestion of biosolids by various pretreatments including utilization of indigenous microbes present in biosolids (T1), the effect of an enzymatic pretreatment (T2), biostimulation by the addition of an external carbon source (T3) and the synergic effect of biostimulation and enzymatic pretreatment (T4). After 28 days of aerobic digestion, total PhACs removal was 44% with T1, which improved to 51%, 54% and 62% in T2, T3 and T4, respectively. Also, total pesticides removal was 10% in T1, which enhanced to 44%, 14% and 54% in T2, T3 and T4, respectively. The extracellular enzyme activities were also monitored in all the treatments and the maximum activities (114 ± 11 U/L lipase, 382 ± 29 U/L phosphatase, 155 ± 8 U/L protease, 304 ± 26 U/L amylase, 108 ± 7 U/L laccase, and 63 ± 2 U/L lignin peroxidase) were observed in T4 after 28 days of digestion. Thus, this study aids in providing changing aspects of enzyme profiles during these processes and the enhanced bioremediation of biosolids through the hydrolytic and oxidoreductase enzymes produced by the indigenous microorganisms.

Exploring the synergic effect of fly ash and garbage enzymes on biotransformation of organic wastes in in-vessel composting system

The aim of the present work was to study the synergic effect of fly ash (FA) and garbage enzymes (GE) on biotransformation of organic wastes in in-vessel composting system. In-vessel composting of organic waste (household + brown in vessel 1) was performed with fly ash (mixed 5% in vessel 2; 10% in vessel 3; 15% in vessel 4; and 20% in vessel 5) by addition of extra carbon source (5%) and garbage enzyme in a fixed-dose (5%) for 15 days and changes in chemical properties (C: N ratio, nitrates, sulphates, phosphates and macro-elements) were analyzed at maturity. Vessel 5 showed better results in terms of organic matter degradability and C: N ratio (13.68) of mature compost. Principal Component Analysis (PCS) also confirmed vessel 5 as the best performing among other vessels. FTIR analysis indicated a major shift in chemical structure of organic waste due to the composting action.

The effect of intermittent drying and wetting stormwater cycles on the nutrient removal performances of two vegetated biofiltration designs

Vegetated biofiltration systems (biofilters) are now a well-established technology for treatment of urban stormwater, typically showing high nutrient uptake. However, the impact of high temporal variability of rainfall events (further exacerbated by climate change) on nitrogen and phosphorus removal processes, within different biofiltration designs, is still unknown. Hence, a laboratory-based study was conducted to uncover mechanisms behind nutrient removal in biofilters across different drying and wetting regimes. Two sets of experimental columns were based on (1) the standard biofiltration design (unsaturated zone only), and (2) combination of unsaturated and saturated (submerged) zone (SZ) with additional carbon source. Columns were watered with synthetic stormwater according to three drying and wetting schemes, exploring 1, 2, 3, 4 and 7-week drying. Hydraulic performance, soil moisture and pollutant removal were monitored. The results show that hydraulic conductivity of SZ design experiences less change over time compared to standard design, due to slower media drying, crack formation and lower plant die-off. Varied drying lengths challenged both designs differently, with 2-week drying resulting in significant drop of performance across most pollutants in standard design (except ammonia), while SZ design was able to retain high performance for up to four weeks of drying, sustaining microbial and plant uptake. Increased oxygenation of SZ columns during short-term drying was beneficial for ammonia and phosphorus removal. While SZ design showed better performance and quicker recovery for nitrogen removal, in regions with inter-rain event shorter than two weeks, the standard design (no saturated zone, no carbon source) can achieve similar if not better results.

Research on the enhanced biological nitrogen removal of wastewater by the ultrasound-hydrolysis acidification of excess sludge.

To simultaneously improve the removal of nitrogen and phosphorus from wastewater with a low C/N ratio and reduce excess sludge production, in this paper, excess sludge ultrasound-hydrolysis acidification (UHA) pretreatment was coupled with the anaerobic-anoxic-oxic (AAO) process to provide carbon source and enhance biological nitrogen removal performance, and the experimental results can be summarized as follows. First, the total nitrogen (TN) concentrations in the effluent of the system decreased from 16.94mg/L to 5.74mg/L, and the removal rate of TN increased by 25.5%. In addition, the concentrations for ammonia nitrogen (NH3 -N) in the system decreased 12.59mg/L, and the removal rate of this index increased by 29.0%. Furthermore, the specific oxygen uptake rate (SOUR) in the anoxic zone increased significantly because the application of UHA products enhanced the microbial activity, and the addition of UHA products had an effect on the microbial community structure in the system. The amounts of denitrifying bacteria such as Betaproteobacteria and Alphaproteobacteria also increased, which enhanced the nitrogen removal efficiency of wastewater biological treatment. PRACTITIONER POINTS: Treatment of excess sludge in UHA device as an additional carbon source. Nitrogen removal efficiency was greatly improved after adding UHA products. Input of UHA products enhanced microbial activity in AAO system. Denitrifying bacteria increased with the addition of UHA products.