Ratio Of Volatile Fatty Acids Research Articles

The growth and nutrient removal properties of heterotrophic microalgae Chlorella sorokiniana in simulated wastewater containing volatile fatty acids

To reduce the high cost of organic carbon sources in waste resource utilization in the cultivation of microalgae, volatile fatty acids (VFAs) derived from activated sludge were used as the sole carbon source to culture Chlorella sorokiniana under the heterotrophic cultivation. The addition of VFAs in the heterotrophic condition enhanced the total nitrogen (TN) and phosphorus (TP) removal of C. sorokiniana, which proved the advantageous microalgae in using VFAs in the heterotrophic culture after screening in the previous study. To discover the possible mechanism of nitrogen and phosphorus adsorption in heterotrophic conditions by microalgae, the effect of different ratios of VFAs (acetic acid (AA): propionic acid (PA): butyric acid (BA)) on the nutrient removal and growth properties of C. sorokiniana was studied. In the 8:1:1 group, the highest efficiency (77.19%) of VFAs assimilation, the highest biomass (0.80 g L−1) and lipid content (31.35%) were achieved, with the highest TN and TP removal efficiencies of 97.44 % and 91.02 %, respectively. Moreover, an aerobic denitrifying bacterium, Pseudomonas, was determined to be the dominant genus under this heterotrophic condition. This suggested that besides nitrate uptake and utilization by C. sorokiniana under the heterotrophy, the conduct of the denitrification process was also the main reason for obtaining high nitrogen removal efficiency.

Ionophore antibiotics and hop cones as regulators of digestion and metabolism in ruminants

The general characteristics of ionophore antibiotics and the mechanisms of their antimicrobial action were analyzed. Two types of ionophore antibiotics are known: those that transport ions across the membrane, and those that form a channel in the cell membrane through which ions pass. Ionophore antibiotics used in animal husbandry belong to the former group (monensin, lasalocid, salinomycin, narasin). They are synthesized by bacteria of the Streptomyces genus. Bacterial cells and rumen fluid differ in ionic composition, which is regulated by active ion transport. As a result, the cytoplasm of bacteria contains more potassium ions, while the rumen fluid, on the contrary, has more sodium ions. Ionophores transport potassium inside the cell and remove sodium outside. The bacteria try to correct this imbalance and require ATP energy to carry out this process. Eventually, energy deficit develops in the bacterial cell and it dies. Ionophore antibiotics affect only the Gram-positive bacteria in the rumen of ruminants, because they cannot penetrate through the cell wall of Gram-negative bacteria. Thus, there is a selective destruction of some types of bacteria, the most sensitive among which are the so-called hyper-ammonia-producing bacteria (HAB). Ionophore antibiotics, which change the breakdown of protein and carbohydrates, change the ratio of volatile fatty acids by increasing the proportion of propionic acid and thus inhibit methanogenesis in the rumen. Ionophore antibiotics are an important antiketotic agent because they reduce the concentration of β-hydroxybutyrate and non-esterified fatty acids in the blood of ruminants. During the transition period, cows have metabolic disorders so they are more prone to infectious diseases due to a decrease in resistance. The use of ionophore antibiotics affects the immune function and resistance to inflammatory processes, which is caused by an indirect influence associated with a lower pathological effect of ketosis and steatosis. Ionophore antibiotics reduce the negative energy balance and its pathological impact on metabolism. The influence of ionophore antibiotics on cow’s milk productivity is mostly absent or insignificant. The study presents characteristics of biologically active substances of hop cones. Hop cones contain biologically active components similar to ionophore antibiotics by action. These are prenylated flavonoids: humulone (α-acid), lupulone (β-acid) and their derivatives. These components of hop cones can be regarded as a potential substitute for ionophoric antibiotics. In particular, lupulone and some other components of hop cones inhibit the activity of Gram-positive bacteria, causing reactions similar to ionophore antibiotics. In addition, hop cones have many other biologically active compounds: phenols, essential oils, and resins, which have antimicrobial, antioxidant, sedative, phytoestrogen, insulin stimulating, immunomodulatory, and antitumor effects.

Stimbiotic supplementation and xylose-rich carbohydrates modulate broiler's capacity to ferment fibre.

Stimbiotics are a new category of feed additives that can increase fibre fermentability by stimulating fibre-degrading microbiota in the gut. The aim of this study was to test, ex vivo, if the microbiota of broilers fed a stimbiotic are better able to ferment different xylose-rich substrates in an ileal and a caecal environment. The ileal and caecal contents from broiler chickens fed a stimbiotic or from a control group were used as an inoculum in the ex vivo fermentation experiment. Different xylose-rich substrates including monomeric xylose (XYL), XOS with DP 2 to 6 (XOS), short DP XOS of 2 to 3 (sDP-XOS), long DP XOS of 4 to 6 (lDP-XOS) and de-starched wheat bran (WB), were added to each ileal and caecal inoculum in fermentation vessels. Total gas, short-chain fatty acids (SCFA) production, bacterial quantification, and carbohydrate utilisation were monitored for 9 h post-inoculation. No significant interactions were observed in any of the parameters measured in either the ileal or caecal contents (p > 0.05). Stimbiotic ileal inocula resulted in higher total gas (p < 0.001) and volatile fatty acid (VFA) (p < 0.001) production, increased numbers of Lactobacillus spp. (p < 0.001), and decreased numbers of Enterococcus spp. (p < 0.01) after 9 h regardless of the xylose-rich substrate added. Stimbiotic caecal inocula resulted in a higher ratio of VFA to branched-chain fatty acids (BCFAs) by up to +9% (p < 0.05). Ileal microbiota were found to preferentially metabolise WB, while caecal microbiota favoured XOS substrates, particularly lDP-XOS. These results indicate that stimbiotics can promote the abundance of lactic acid bacteria involved in the establishment of fibre-degrading bacteria and VFA content in the gut, which could have beneficial effects on broiler performance. Further, ileal and caecal microbiota differ in their utilisation of different substrates which may impact the effectiveness of different stimbiotic products.

Effect of anaerobic duration on biological phosphorus removal in reversed AAO process (anoxic-anaerobic-oxic).

In this study, the effect of anaerobic duration on phosphorus (P) removal in reversed AAO (anoxic-anaerobic-oxic) process was investigated using synthetic wastewater (with different volatile fatty acid (VFA) ratios) and real wastewater. The P, poly-hydroxyalkanoates (PHAs), dehydrogenase activity (DHA), polyphosphate kinases (PPK), electron transfer system (ETS), and adenosine 5'-triphosphate (ATP) were determined as indicators. The highest P removal efficiencies were achieved at an anaerobic duration of 3, 4, and 6h for 15, 30, and 60% VFA ratio in synthetic wastewater. The amount of the released P and stored PHAs can be manipulated by different anaerobic durations, but the P removal efficiency cannot be guaranteed with higher stored PHAs. Additionally, the energy metabolism confirmed the significance of anaerobic duration extension on microbial activity. The highest values of four indicators were all achieved at anaerobic duration of 4h with 30% VFAs ratio which achieved the highest P removal efficiency. Real wastewater experiments also proved the reproductivity of these results. We defined this phenomenon as the "hunger response" where microorganisms responded to suppression (anaerobic duration extension) with higher activity after the end of the anaerobic condition. These results can provide references for better design and operation of biological phosphorus removal in RAAO process.

Evaluation of different ensiling methods for Saccharina latissima preservation: influence on chemical composition and in vitro ruminal fermentation

ABSTRACT Saccharina latissima is a brown seaweed that could be used in ruminant feeding, but its fast deteriorating and seasonal growth nature limit their utilisation in the practice. Ensiling could be used as a preservation method, but information of its effects on the nutritional value of the seaweed is limited. This study evaluated the in vitro ruminal fermentation of different S. latissima silages using ruminal inoculum either from goats fed a mixed diet (60:40 oat hay:concentrate) or from sheep fed a high-forage diet (90:10 alfalfa hay:concentrate) to simulate different small ruminant production systems. S. latissima was ensiled in vacuum bags without additives (Control), with formic acid (4 g/kg seaweed; FA), with lactic acid bacteria (LAB) or with LAB after a pre-wilting treatment to reach a seaweed dry matter (DM) content of 30% (30LAB). Ensiling S. latissima decreased (p < 0.05) the content in DM, neutral detergent fibre and total extractable polyphenols, but nitrogen and fat content were unaffected. For both ruminal inoculums, ensiling decreased (p < 0.05) the asymptotic gas production after 120 h of fermentation (excepting for FA silage with goats’ inoculum), but the total volatile fatty acid (VFA) production was unaffected. The VFA profile shifted towards greater (p < 0.05) acetate and lower (p < 0.05) propionate proportions in all silages compared with the pre-ensiling S. latissima. When goats inoculum was used, greater (p < 0.05) CH4 production compared with pre-ensiling S. latissima was observed in all silages, except Control one, which led to greater (p < 0.05) CH4/total VFA ratio. In contrast, no differences among samples (p > 0.05) in either CH4 production or CH4/total VFA ratio were observed when sheep’ inoculum was used. Fermentation of all samples started earlier with goats’ inoculum than with sheep’ inoculum, which was attributed to the different diet fed to the animals. These results suggest that ensiling S. latissima with either formic acid or lactic acid bacteria could be a viable conservation method to preserve the nutritive value.

Adsorptive recovery of volatile fatty acids from wastewater fermentation broth

This work developed an adsorptive separation and recovery process for anaerobically generated volatile fatty acids (VFAs) from swine wastewater fermentation. Batch adsorption studies were conducted using several weak anion exchange resins and synthetic adsorbent resins to identify a suitable candidate. Relite RAM2 with a tertiary amine functional group showed the highest adsorption (over 98%) of hexanoic acid. Under the different pH values (1.8–7.5) and extraction temperatures (30–50 °C), the highest adsorption was observed at a pH of 3.2, which is below the pKa of hexanoic acid, at all the evaluated temperatures. A full factorial design was used to optimize the resin and VFA concentrations, wherein over 99% adsorption could be achieved when the ratio of VFA to resin was below 0.23 (g/g) for model solution (VFAs in water). The adsorption equilibrium could be achieved within 30 min of contact time and 0.5% w/v NaOH was identified as a suitable desorption agent. Under the optimal conditions, 65–72% of VFAs present in fermentation broth was adsorbed, which was increased to 72–76% by using fresh resins. The VFAs adsorption and recovery efficiency were maintained for 9 successive cycles without requiring extensive resin washing and regeneration for both model solution and fermentation broth. Overall, the work presents a comprehensive study for resin adsorption to recover VFAs and provides a potential industrial-relevant process to recover VFAs from fermentation broth.

WAYS TO REDUCE THE EFFECT OF MYCOTOXINS ON THE CATTLE BODY

Mycotoxins are a consequence of mold growth. Fungi produce mycotoxins under conditions of changing tem-perature, humidity or aeration, as well as in the presence of aggressive agents. The problem of mycotoxicosis is cur-rently relevant. It has been proved that the use of the mycotoxin adsorbent Novazil Plus in cow diets helps to reduce the effect of mycotoxins on the animal body, which is expressed by the most optimal processes of ruminal digestion, the optimal ratio of volatile fatty acids, an increase in the total number of microorganisms by 8.15-9.54%, as well as an increase in the productivity of cows with simultaneous improvement of quality indicators, in particular, a decrease in the concentration of Mycotoxin Aflatoxin M1 in milk. The use of the Best-Sil bioconservative contributed to improving the quality characteristics of the finished silage, reducing the accumulation of mycotoxins in it, and feeding such silage to cows also contributed to obtaining products of higher quality.

Features of rumen digestion of cows when an enzyme feed additive is included in the basic ration

Under the influence of microorganisms 95 % of sugars and starch, 70 % of fiber and 40–80 % of protein are broken down in the fore stomachs. Since the microfl ora of the rumen cannot always cope with the digestion of a large amount of coarse feed, enzyme drugs designed to increase productivity and preserve animal health come to their aid. The use of enzyme additives is relevant and allows us to prevent the action of anti-nutritional factors of feed, increase the activity of endogenous enzymes, thereby contributing to the increase in metabolic processes in the body and increase milk productivity. The purpose of this work was to study the features of microbial processes in the rumen of lactating cows when the multicomponent enzyme feed additive Kormomix® Enzyme was included. The use of the enzyme additive aff ected the physics and chemical parameters of the rumen fl uid. The pH concentration in all groups was the same. The volatile fatty acids in the 2nd and 3rd experimental groups were on the same level as the control. In the 1st experimental group, there was a decrease in volatile fatty acids by 1,15 mmol/100 ml compare with control group. The assimilation of ammonia in animals of the 2nd experimental group, which received 50 g /head /day of the enzyme additive, was higher in compare with the control group. The ratio of volatile fatty acids in the rumen fluid of cows of the experimental groups has changed towards the increase in the proportion of acetic acid. The composition of the bacterial community of the rumen improved with the inclusion of 50 g/head/day of the enzyme additive Kormomix® Enzyme. The number of cellulolytic microorganisms exceeded the control level by 6,45 abs.%. Thus, the use of the enzyme additive led to the intensification of microbiological processes in the rumen of cows.

Performance and mechanisms of enhanced hydrolysis acidification by adding different iron scraps: Microbial characteristics and fate of iron scraps.

HA, as one of low-carbon pre-treatment technology could be enhanced by packing of iron or iron oxide powder for enhancing the transformation of large molecular weight to generate volatile fatty acids (VFAs) for fuel production. However, the controversy of iron strengthening the HA and inherent drawbacks of iron oxide, such as poor mass transfer, and difficult recovery, limit this pretreatment technology. Clean and rusty iron scraps were packed into an HA system to address these issues while focusing on the system performance and the response of core bacterial and fungal microbiomes to iron scrap exposure. Results showed that clean and rusty iron scraps can significantly improve the HA performance while considering hydrolysis efficiency (HE), acidification efficiency (AE) and VFAs production, given that VFAs ratios (Cacetate: Cpropionate: Cbutyrate) were changed from the 14:5:1 to 14:2:1 and 29:4:1, respectively, and the obtained VFAs ratios in iron scraps addition systems were more closely to the optimal VFAs ratio for lipids production. Redundant and molecular ecological network analyses indicated that iron scraps promote the system stability and acidogenesis capacity by boosting the complexity of microbes’ networks and enriching core functional microbes that show a positive response to HA performance, among which the relative abundance of related bacterial genera was promoted by 19.71 and 17.25% for RRusty and RClean systems. Moreover, except for the differences between the control and iron scraps addition systems, the findings confirmed that the RRusty system is slightly different from the RClean one, which was perhaps driven by the behavior of 6.20% of DIRB in RRusty system and only 1.16% of homoacetogens in RClean system when considering the microbial community and fate of iron scraps. Totally, the observed results highlight the application potential of the iron scrap-coupled HA process for the generation of VFAs and provide new insights into the response of different iron scraps in microbes communities.

Cyberlindnera jadinii yeast as a protein source in early- to mid-lactation dairy cow diets: Effects on feed intake, ruminal fermentation, and milk production

We examined the effects of substituting soybean meal with either yeast protein from Cyberlindnera jadinii or barley in concentrate feeds on feed intake, ruminal fermentation products, milk production, and milk composition in Norwegian Red (NRF) dairy cows. The concentrate feeds were prepared in pellet form as soy-based (SBM; where soybean meal is included as a protein ingredient), yeast-based (YEA; soybean meal replaced with yeast protein), or barley-based (BAR; soybean meal replaced with barley). The SBM contained 7.0% soybean meal on a dry matter (DM) basis. This was replaced with yeast protein and barley in the YEA and BAR concentrate feeds, respectively. A total of 48 early- to mid-lactation [days in milk ± standard deviation (SD): 103 ± 33.5 d] NRF cows in their first to fourth parity and with initial milk yield of 32.6 kg (SD = 7.7) were allocated into 3 groups, using a randomized block design, after feeding a common diet [SBM and good-quality grass silage: crude protein (CP) and neutral detergent fiber (NDF) content of 181 and 532 g/kg of DM, respectively] for 14 d (i.e., covariate period). The groups (n = 16) were then fed one of the dietary treatments (SBM, YEA, or BAR) for a period of 56 d (i.e., experimental period). The concentrate feeds were offered in split portions from 3 automatic feeders using electronic identification, with ad libitum access to the same grass silage. Dietary treatments had no effect on daily silage intake, total DM intake, or total NDF intake. Dietary CP intake was lower and starch intake was higher in the BAR group compared with the other groups. Ruminal fluid pH, short-chain volatile fatty acid (VFA) concentrations, acetate-to-propionate ratio, and non-glucogenic to glucogenic VFA ratio were not affected by dietary treatments. No effects of the dietary treatments were observed on body weight change, body condition score change, milk yield, energy-corrected milk yield, milk lactose and fat percentages, or their yields. In conclusion, yeast protein can substitute conventional soybean meal in dairy cow diets without adverse effect on milk production and milk composition, given free access to good-quality grass silage.

Potential of food waste hydrolysate as an alternative carbon source for microbial oil synthesis

Volatile fatty acids (VFAs) have great potential as cheap raw materials in microbial oil synthesis and reducing the cost of substrates is essential for the development of microbial oil biosynthesis. In this study, the food waste hydrolysate and synthetic VFAs media were both used as substrate to synthesis microbial oil. The optimal short-chain VFAs ratio for microbial oil synthesis is 20:5:5 and increasing the proportion of propionic acid is the key to obtaining odd fatty acids. The hydrolysate obtained from food waste under the total solid condition of 2:1 and pH 5 is the most suitable medium for microbial oil synthesis. The biological products obtained from food waste hydrolysate were comparable to synthetic VFAs media, obtaining a 34.02% of lipid content. Results prove that food waste hydrolysate has great potential as the available feedstock for microbial oil synthesis and a promising application value in food waste recycling

The effect of volatile fatty acids on the growth and lipid properties of two microalgae strains during batch heterotrophic cultivation

To overcome the bottlenecks of waste resource utilization and energy shortage that restrict the commercial production of microalgae biodiesel, volatile fatty acids (VFAs) derived from activated sludge were used as the sole carbon source to culture oleaginous microalgae Chlorella pyrenoidosa FACHB-1216 and Scenedesmus quadricauda FACHB-1297 under the mixotrophic and heterotrophic cultivation. Four VFAs ratios (acetic acids (AA): propionic acids (PA): butyric acids (BA)) were tested to determine the effects and mechanisms of the VFAs on the two microalgae. The highest lipid content (29.54%) and lipid production (71.10 mg L−1) were achieved by S. quadricauda at the VFAs ratio of 6: 1: 3 under heterotrophic condition, with 46.27% and 67.52% removal efficiencies of total nitrogen and phosphorus, respectively. The assimilation efficiency of AA was the highest at 73.37%, followed by that of PA and BA. For C. pyrenoidosa, VFAs promoted the rapid reproduction within 2 days under the heterotrophic condition at different initial inoculation densities. At the optimal VFA ratio, algae achieved the highest biomass concentration (0.14 ± 0.02 g L−1), with a specific growth rate of 0.91 d−1 and biomass productivity of 125.17 mg L−1 d−1. The removal rates of total nitrogen and phosphorus were 47.03% and 74.40%, respectively, and the assimilation efficiency of AA was the best (61.06%). High AA assimilation efficiency under the heterotrophic condition was beneficial for the algal growth and lipid accumulation. These results simultaneously produced microalgae-based bioenergy and recycled VFAs in anaerobically digested effluent.

Partial berseem hay replacement by Panicum maximum grass on caecal fermentation activity, performance, and carcass characteristics of growing rabbits

The aim of this study was to evaluate the effect of partial substitution of berseem hay (BH) with Panicum maximum (PM) on the growth performance, nutrient digestibility, carcass characteristics, and caecal fermentation activity of rabbits. Eighty-four growing male NZW rabbits aged six-week-old with an initial body weight of 746.43 ± 1.7 g, were randomly assigned to four groups (21 in each). Rabbits were fed the following diets for 70 days in a completely randomized experimental design: PM0 (30% BH) as a control, PM25 (7.5% PM + 22.5% BH), PM50 (15% PM + 15% BH), and PM75 (22.5% PM + 7.5% BH). The results indicated that the approximate analysis of PM was10.06 % crude protein, 31.75% crude fibre, and 2.27% crude fat. Final body weight, daily weight gain, and daily feed intake for rabbits decreased gradually (P < 0.05) with increasing PM levels in the diet, with no significant differences between PM0 and PM25 groups. Both groups PM0 and PM25 were similar in feed conversion ratio and better than that of groups PM50 and PM75. The nutrient digestibility decreased with increasing the rate of PM in rabbit rations (P < 0.05), with no significant difference between PM25 and control group. Carcass weight gradually decreased but the liver and kidney weights increased (P < 0.05) as PM levels increased in the rabbit rations. Likewise, the content of crude protein and ether extract decreased with increasing PM in the rations of rabbits. There were no significant differences in ash content between the treatment groups. Under the influence of the applied PM rations, high levels of 50% and 75% caused a significant rise in the pH value of caecum contents. The caecal NH3-N concentration increased significantly in response to increasing PM levels in the diet. Conversely, total volatile fatty acids (VFAs) decreased significantly from 68.46 to 61.35 mmol L−1. The proportions of acetic and butyric acids, and the non-glucogenic VFAs to glucogenic VFA ratio (NGGR) significantly decreased, while the proportions of propionic and valeric acids, and fermentation efficiency increased significantly with increasing PM levels in the diet. The results indicated that partial replacement of BH with 25 % PM did not adversely affect the growth performance or health of growing rabbits.

Optimisation of methane fermentation as a valorisation method for food waste products

The aim of the study was to optimize methane fermentation of food waste products based on the composition of substrates mixture and technical parameters of anaerobic digestion to obtain the highest biogas and methane production. The study was conducted in the laboratory scale in the mesophilic (37°C) and thermophilic (55°C) conditions. Also the effects of the organic loading rates (OLRs) on the biogas productivity and composition were analysed. The highest biogas yield was obtained in mesophilic digestion of the substrates mixture containing 50% of meat, 40% dairy products, 10% fruit and vegetables. It amounted to 740.4 ± 19.9 cm3·g ODM−1 of biogas with 68.6 ± 1.8% of methane. Biogas potential in thermophilic digestion was from 2.1 to 2.8 times lower for analogical feedstock. It was caused by high concentration of volatile fatty acids (VFAs) in the reactor chamber. The ratio of VFAs to alkalinity was on the level from 0.5 ± 0.1 to 0.8 ± 0.1. In continuous experiments, the average biogas production rate was from 2646.9 ± 117.3 cm3·d−1 for OLR of 2 g ODM·dm−3·d−1 to 9893.4 ± 362.0 cm3·d−1 for OLR amounting to 8 g ODM·dm−3·d−1. Methane content in biogas was between 65.6 ± 2.5 and 65.5 ± 1.9%, respectively. It was confirmed that applying OLR above 6 g ODM·dm−3·d−1 causes inhibition of methane fermentation.

Bioconversion of volatile fatty acids into lipids by the oleaginous yeast Apiotrichum porosum DSM27194

Volatile fatty acids (VFA) derived from waste organics provide economical feedstocks for fuels and oleochemicals production. In this study, the valorization of VFA into microbial lipids by the oleaginous yeast Apiotrichum porosum DSM27194 was investigated. A. porosum DSM 27194 was able to assimilate different VFA mixtures containing acetic, propionic and butyric acid at different ratios for lipid production. By using a two-stage automated fed-batch fermentation strategy with glucose as initial carbon source and VFA mixtures as both carbon source and buffering agent, a dry cell mass concentration of 26.5 g/L with lipid content of 36.2% was achieved with the VFA ratio of 6:1:1 (acetic acid:propionic acid:butyric acid). Fatty acid composition profiles indicated that the lipid derived from VFA is better suited for biodiesel production compared to glucose as carbon source. Moreover, corn stover hydrolysate containing VFA was applied as raw feedstock. Excitingly, A. porosum DSM 27194 could consume all kinds of carbon source within the hydrolysate fast and simultaneously resulting in 28.0 g/L of dry cell mass containing 44.3% of lipid. This study provides a promising oleaginous yeast chassis of A. porosum DSM 27194 and an economical fermentation strategy of two-stage automated fed-batch fermentation for microbial lipid production from low-value VFA derived feedstocks.

Decomposition process of cefotaxime sodium from antibiotic wastewater by Up-flow Blanket Filter (UBF) reactor: Reactor performance, sludge characteristics and microbial community structure analysis

In this study, a novel Up-flow Blanket Filter (UBF) reactor was applied to the degradation of antibiotic wastewater. The experiments showed that when the hydraulic retention time (HRT) was 24 h and the ratio of volatile fatty acids (VFA) to alkalinity (ALK) was 0.3, the best removal efficiency was achieved in the combined packing UBF reactor, and the COD removal efficiency reached 80.1%–84.6%, exhibiting a significant difference in reaction performance from the other two reactors (P < 0.05) and a good efficiency of cefotaxime sodium removal. Moreover, the microstructure and surface characteristics of the reactor fillers were studied through scanning electron microscope (SEM) analysis, which showed that three fillers all had biofilm adhesion, but the combined packing gave best performance. Energy dispersive spectrometer (EDS) tests indicated abundant element components in the combined packing. The particle size distribution of sludge was also considered in the experiment, and the result showed the particle size of sludge increased with the operation of the reactor. In addition, microbial community structures of sludge and biofilm with the combined packing were analyzed. High-throughput sequencing confirmed the existence of Pseudomonas, which had good adaptability to antibiotic wastewater and became the dominant bacteria. Decomposition process of cefotaxime sodium after hydrolysis and anaerobic treatment was analyzed through Fourier transform infrared spectroscopy (FTIR). The reactor, which is economical, exhibited favorable performance in degrading the pollutions in the antibiotic wastewater.

Enhancement of food waste thermophilic anaerobic digestion through synergistic effect with chicken manure

Anaerobic co-digestion in thermophilic condition leads to efficient waste treatment and energy recovery through accelerated and enhanced synergism. The performance of anaerobic co-digestion of food waste with chicken manure was investigated for overcoming the challenges due to process inhibition during mono-digestion of food waste. The bench scale anaerobic Continuously Stirred Tank Reactor (CSTR) system with the working volume of 87 L in wet condition with 10% total solids content was used for this study. Though thermophilic food waste anaerobic digestion indicated high methane yield and solids reduction, the process stability was affected at higher loading. Whereas, the reduction in FOS/TAC value (the ratio of volatile fatty acids to total alkalinity) through co-digestion indicated the higher capacity for organic loading rate in the anaerobic co-digestion system due to synergistic effect of microorganisms, buffering capacity and nutrient balance by C/N adjustment in the feedstock. Moreover, the percentage increases of specific methane yields in co-digestion compared with mono-digestion was found to be 33.2%, 10.4%, 12.1% and 89.9% at organic loading rates (OLR) of 1, 2, 3 and 4 kg VS‧m−3‧d−1 respectively, as a consequence of the improvement in stability through co-digestion.

Anaerobic co-digestion assessment of olive mill wastewater and food waste: Effect of mixture ratio on methane production and process stability

The Olive oil industry is one of the most important agro-industrial sectors in the Mediterranean countries, in which Morocco is the world's 5th largest olive oil producer. By-products of this agro-industry such as OMWW and olive mill pomace represent a major challenge for the environment. The high concentration of polyphenols in OMWW and the lack of nitrogen make AD of this substrate difficult. AcoD of OMWW with other substrates is an alternative solution to fill this gap. In the present study, AcoD of OMWW with FW from the Ibn Tofail University campus restaurant was investigated, in order to enhance AD of OMWW in terms of methane production and process stability. Different co-substrates were prepared and tested, in which the content of OMWW varied from 20 to 80 %.The MY and biodegradability were optimal at the mixture 20 % OMWW: 80 % FW showing the values of 302.16 ± 3.04 mLSTP CH4.gVS−1 and 86.0 ± 4.1 % respectively. The process stability was investigated through the alkalinity and the volatile fatty acids ratio VFA/ALK, and the results show that all mixtures were stable except the control test mono AD of OMWW. This stability might be due to the simultaneous presence of ammonia ions from the decomposition of proteins contained in FW and bicarbonate ions. The OLR increased when the added loads increased throughout the conducted experiments. The OLR of the mixture 20 % OMWW: 80 % FW was 2.0 ± 0.1 kg VS. m-3.d−1) higher than OLR of control test (1.45 ± 0.05 kg VS.m-3.d−1). Furthermore, two kinetics models were applied (modified Gompertz model and the Logistic model). The results shown that both models had a good conformity, and the modified Gompertz model was the more appropriate showing a higher values of R2 than logistic model. Moreover, the lag time decreased when the OMWW proportion increased.

Towards biodegradable polyhydroxyalkanoate production from wood waste: Using volatile fatty acids as conversion medium

Production of polyhydroxyalkanoate (PHA) via mixed microbial consortia is a potential economic alternative responding to the current demand for functional greener materials to replace traditional petroleum-basedpolymers. The goal of this study was to synthesize PHA using volatile fatty acids (VFAs) obtained from the co-fermentation of pretreated wood waste and sewage as carbon source. High PHA yield of 0.71 g COD PHA/g COD VFAs and PHA content of 50.3 g PHA/100 g VSS were obtained at VFAs ratio (even:odd) of 88:12 after seven cycles cultivation. Even acids were more suitable for accumulating PHA as the preferred carbon source than odd acids, resulting in 3-hydroxybutyrate being the main monomer. PHA production achieved to the highest value of about 2639 mg COD/L at 1400 mg COD/L VFAs concentration. The bacterial genera displayed a highly diverse of the microbial community for the synthesis of PHA.

Effects of overnight wilting and additives on the fatty acid profile, α-tocopherol and β-carotene of whole plant oat silages

The aim of the present study was to clarify whether the 3 advised additives (sodium caseinate, SC; propionic acid additive, PA; and tert-butylhydroquinone, TBHQ) could reduce the losses of polyunsaturated fatty acids (PUFA), α-tocopherol and β-carotene in wilted (overnight wilting for 14 h) and non-wilted whole plant oats (Avena sativa L. cv. Esk, dough stage) silage after ensiling for 100 d. Harvested whole plant oats from the 5 fields (100 m2 per field) were separately ensiled according to the following experiment design: 2 wilting levels (whole plant oat with and without overnight wilting were named as WWO and FWO, respectively) × 4 additives (without additive as the control, and with the 3 advised additives) × 4 copies per treatment. The additives-treated FWO and WWO were separately filled in silos (polyvinyl chloride bottle, 1 L), immediately. After ensiling for 100 d at room temperature, silos were opened and silages were sampled. Overnight wilting didn’t influence the contents of linoleic acid (C18:2n6) (P > 0.05), α-linolenic acid (C18:3n3) (P > 0.05) but resulted in losses of α-tocopherol (20.8 %) (P < 0.05) and β-carotene (27.4 %) (P < 0.05) in whole plant oats before ensiling due to multiplication of microbes, e.g., aerobic bacteria and yeasts. Compared with additive-untreated FWO silage, poorer fermentation quality was found in additive-untreated WWO because lactic fermentation was weakened while butyric fermentation was stimulated. Compared with the material before ensiling, ensiling increased contents of C18:2n6, C18:3n3 and PUFA either in FWO or WWO silage (P < 0.05) due to the high ratio of volatile fatty acids to lactic acid. The ensiling increased β-carotene loss (P < 0.05) but accumulated α-tocopherol in either FWO or WWO silage (P > 0.05). Moreover, only PA improved fermentation quality of FWO and WWO silages, demonstrated by the lowest pH and ammonia-N content and the highest lactic acid content (P < 0.05), and preserved C18:2n6, C18:3n3 and PUFA in FWO silage. All additives did not reduce α-tocopherol loss either in FWO or WWO silage but decreased β-carotene loss in FWO silage. In conclusion, using advised additives did not reduce the oxidation losses of PUFA, α-tocopherol, and β-carotene in overnight wilting whole plant oat silages, and PA is a potential additive to improve fermentation quality and preserve main PUFA, α-tocopherol, and β-carotene in non-wilted whole oat silages.