Effects Of Co-substrates Research Articles

A Review on the Anaerobic Co-Digestion of Livestock Manures in the Context of Sustainable Waste Management

As the worldwide demand for meat per person is continuously increasing, there is a corresponding rise in the number of livestock animals, leading to an increase in livestock manure. Selecting appropriate treatment technologies for livestock manures is still a complex task and considerable debates over this issue persist. To develop a more comprehensive understanding of the manure treatment framework, this review was undertaken to assess the most utilized manure management technologies and underscore their respective challenges. Anaerobic digestion has become a commercial reality for treating livestock manures. However, the mono-digestion of single substrates comes with certain drawbacks associated with manure characteristics. Anaerobic co-digestion, involving the utilization of multiple feedstocks, holds the potential to overcome these limitations. Extensive research and development have underscored numerous intrinsic benefits of co-digestion. These include improved digestibility resulting from the synergistic effects of co-substrates and enhanced process stability. This review underscores the limitations associated with the mono-digestion of livestock manures and critically evaluates the advantages of their co-digestion with carbon-rich substrates. Additionally, this review delves into key livestock manure management practices globally, emphasizing the significance of co-digesting livestock manures while addressing the progress and challenges in this field.

Enhancing biogas production from food waste and water hyacinth: effect of co-substrates and inoculum ratios

Enhancing biogas production from food waste and water hyacinth: effect of co-substrates and inoculum ratios

The efficiency of the microbial fuel cell reactor in biodegradation of methyl tertiary butyl ether and electricity generation from wastewater: Effects of co-substrate, surfactant, and membrane changes

This study highlights the promising potential of utilizing an MFC reactor equipped with Nafion 117 and PVA/GA membranes. This innovative and cost-effective approach has proven to be highly effective in addressing the challenge of treating methyl tertiary butyl ether (MTBE) in wastewater, while also offering the added benefit of electricity generation. Biodegradation efficiency and electricity generation were assessed in this study using co-substrates such as glucose (GLS) and sodium acetate (SAC), in addition to surfactants like sodium dodecyl sulfate (SDS) and cetyltrimethylammonium bromide (CTAB). The MTBE concentration ranged from 10 to 200 mg/L, and it was quantified in the samples through gas chromatography with a flame ionization detector (GC–FID). To explore the structural characteristics of Nafion 117 and PVA/GA membranes, we conducted field emission scanning electron microscopy (FESEM), Fourier-transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD) analyses. The maximum biodegradation efficiency of MTBE (%) in MFC reactors with Nafion 117 and PVA/GA membranes was found to be 93.3% and 89.8%, accompanied by maximum production voltages (mV) of 895 mV and 853 mV, respectively. This was achieved with the addition of SAC co-substrate and SDS surfactant. Notably, the addition of co-substrate had a more significant impact compared to the surfactant. Simultaneously adding both the co-substrate and surfactant had a substantial effect on both the biodegradation efficiency (%) of MTBE and the generated voltage. Based on these findings, it can be concluded that the MFC reactor equipped with Nafion 117 and PVA/GA membranes is capable of effectively breaking down MTBE. However, due to its lower cost, the PVA/GA membrane may be considered a more economical choice. Therefore, the utilization of an MFC reactor featuring Nafion 117 and PVA/GA membranes holds great promise as an efficient approach for treating MTBE in wastewater, while concurrently generating electricity.

Optimizing the malathion degrading potential of a newly isolated Bacillus sp. AGM5 based on Taguchi design of experiment and elucidation of degradation pathway

Malathion, a pesticide used to control pests in crops, vegetables, fruits, and livestock. Its widespread and indiscriminate usage has ensued in different ecological issues, thus, it's vital to remediate this insecticide. Malathion degrading bacterium Bacillus sp. AGM5, isolated from pesticide contaminated agricultural field was cultured in presence of different malathion concentrations under aerobic and energy restrictive conditions and was found effective at malathion degradation. Recovered malathion was extracted based on QuEChERS approach and then analyzed by UHPLC. About 39.5% of malathion biodegradation was observed at 300µlL-1 after 96h of incubation with the tested bacteria which increased to 58.5% and 72.5% after 240, and 360h of incubation, respectively. To further enhance malathion biodegradation, the effects of co-substrates, pH, temperature, initial malathion concentration, agitation (rpm), and inoculum size were evaluated using Taguchi methodology. Taguchi DOE's ability to predict the optimal response was established experimentally via optimised levels of these factors (glucose-0.1%, yeast extract-0.1%, inoculum size-2%wv-1, malathion concentration 300 µlL-1, rpm-150, pH-7, temperature 40°C), whereby biodegradation rate was enhanced to 95.49% after 38h. Confirmation of malathion biodegradation was performed by UHPLC, Q-TOF-MS, GC-MS analysis and a possible degradation pathway was proposed for malathion biodegradation. First order kinetic model was appropriate to describe malathion biodegradation. The Taguchi DOE proved to be viable tool for optimizing culture conditions and analysing the interactions between process parameters in order to attain the best feasible combination for maximum malathion degradation. These results could influence the development of a bioremediation strategy.

Optimization of process parameters for biodegradation of malathion by Micrococcus aloeverae MAGK3 using Taguchi methodology and metabolic pathway analysis

In this study, a previously isolated bacterial strain, Micrococcus sp. MAGK3 was employed to explore its malathion biodegradation potential. A considerable degradation (66.79%) was attained with malathion (0.03%) being the sole carbon source after 240 h of incubation. To enhance malathion biodegradation, effects of co-substrates, pH, temperature, initial malathion concentration, agitation (rpm), and inoculum size were evaluated using Taguchi methodology. Experiments with various combinations of factors were conducted, and results in respect of malathion biodegradation were evaluated in the Qualitek-4 software to determine the key effect of individual factors, their interaction effects, and optimal levels of process factors. All parameters contributed to malathion biodegradation, and Taguchi DOE's ability to predict optimum response, was established by experimentation via optimized levels of factors (carbon source 0.1%, nitrogen source 0.1%, pH 7, temperature 35 °C, pesticide concentration 0.03%, agitation 150 rpm, and inoculum size 2%(w/v). Results confirmed that pesticide concentration caused the maximum impact (34.09%) on malathion degradation followed by nitrogen source (32.11%), temperature (20.99%), RPM (6.55%), inoculum size (3.26%), carbon source (2.81%) and pH (0.2%). Before optimization, Micrococcus sp. MAGK3 had an average degradation of 57.94% within 168 h, but after optimization, the rate of biodegradation improved to 87% within 38 h. Confirmation of malathion biodegradation was performed by UHPLC, and GC-MS analysis and a possible degradation pathway was proposed for malathion biodegradation by Micrococcus sp. MAGK3. For the time being, this is the first publication to employ the Taguchi design of experiment to optimize the degradation of malathion by Micrococcus sp. MAGK3.

Efficient and economical production of polyhydroxyalkanoate from sustainable rubber wood hydrolysate and xylose as co-substrate by mixed microbial cultures

Using co-substrate to accumulate polyhydroxyalkanoate (PHA) is an efficient approach to reduce production cost and improve yield of PHA. In the study, PHA was biosynthesized under full aerobic mode by using rubber wood hydrolysate and xylose co-substrate as the carbon source. The effects of co-substrate on PHA production, microbial community and carbon conversion were explored. The results showed that proper addition of xylose was beneficial for the synthesis of PHA and monomer 3-hydroxyvalerate (3HV). Higher conversion yield of substrate-to-PHA (YPHA/S) of 0.933 g COD PHA/g COD S and PHA content of 43.6 g PHA/100 g VSS were gained at co-substrate ratio of 1:1. Likewise, under this condition, PHA production also reached the highest value of 1849 mg COD/L (1088 mg/L). Moreover, the addition of xylose created a favorable screening of PHA dominant strains, improved the conversion of carbon source, and saved 72.3% of feedstock consumption.

Effects of co-substrates’ mixing ratios and loading rate variations on food and agricultural wastes’ anaerobic co-digestion performance

Tunisia is one of the developing countries which faces crucial challenges, the most prominent of which are the production of organic waste, the need for an appropriate waste treatment, and the demand for water and energy conservation. To this end, the present research was designed to develop a technical concept on closed cycle “biowaste to bioenergy” treating food waste (FW) through combined biological processes. In this approach, semi-continuous anaerobic co-digestion (ACoD) of FW, wheat straw (WS), and cattle manure (CM) was tested to investigate the relationship between the effect of the feedstock mixtures and C:N ratio on biogas and digestate generation at different organic loading rates (OLRs) ranging from 2 to 3.6 kg VS/m3.d. Results showed that the mono-digested FW was optimal and reached 565.5 LN/kg VSin at an OLR of 2.4 kg VS/m3.d, and then a drop of biogas production was recorded. However, for co-digested substrates, the optimum mixture ratio was FW:CM 75:25, where 62%, 39.89%, 91.26%, 130.9%, and 119.97% of the biogas yield improved for OLRs ranging from 2 to 3.6 kg VS/m3.d, respectively. Admittedly, the target of this work was to enhance the ACoD process, but it also examined the exploitation of different AD effluents. Therefore, special attention was paid to the generated digestates to decide how it can be efficiently upcycled later. Thus, the closed cycle “biowaste to bioenergy” treatment met two of the major Tunisian concerns: efficient organic waste management and sustainable bioenergy production.

Comparative Anaerobic Co-Digestion Effects of Some Agricultural Biomass on Their Digestates Biochemical Properties

The huge agro-industrial biomass wastes had engendered the need for appropriate treatment technology, which could be deployed to sustainably manage and convert them to useful by-products. Consequently, the comparative anaerobic co-digestion effects of some agricultural biomass on their digestates biochemical properties were conducted. Twelve (12) replicates slurries from four mixing ratios of maize cob, poultry droppings and cow dung (1:0, 1:0, 1:0 and 1:1:1) as treatments TA, TB, TC and TD respectively, were separately digested in 13.6L locally fabricated batch-digester reactors, for eight weeks. Proximate and amino acids constituents were evaluated by standard procedure prior to and at post anaerobic digestion (AD). The biogas yields followed the sequence of TD (2200.7ml/kg) > TB (2197.9ml/kg) >TC (2079.0ml/kg) > TA (1713.2ml/kg), showing co-substrate effects. Proximate assay depicted a decrease in crude lipid across the treatments, with TC (86.82%) and TD (64.66%) as highest and lowest values. Crude fiber and nitrogen free extract had similar observation, apart from TB and TC with increased values. Percentage moisture and percentage ash contents increased across treatments. Carbon - Nitrogen ratio reduction (C/N Reduction) was in the range of 12.94 -85.79%. The Percentage chemical oxygen demand reduction (CODR), followed the order of TA (46.81%) > TB (34.15) >TC (25.81%) >TD (8.00%). There was increased histidine, glycine, cystine, methionine, total nonessential amino acids (TNEAA) and total aromatic amino acids (TArAA), with decrease in aspartic acids and serine. Percentage arginine, threonine, glutamic acid, proline, alanine, isoleucine, tyrosine, total amino acids (TAA) and total essential amino acid (TEAA) decreased only in TB. While, only TA had Percentage increased lysine (25.00%), valine (40.98%) and TArAA (6.13%), with phenylalanine unaffected (0.00%), Percentage leucine of TB (60.14%) and TD (23.08%) were reduced after AD. The process had revealed the alternative waste management, energy options, and useful industrial by-products for agro-allied industries.

Factors affecting microbial lipids production by Yarrowia lipolytica strains from volatile fatty acids: Effect of co-substrates, operation mode and oxygen

Volatile fatty acids (VFAs), which can be generated by acidogenesis of organic wastes, are important building blocks for chemicals production, and are intermediates in many bioprocesses such as microbial lipids production. Important factors affecting the bioconversion of VFAs (acetate, propionate and butyrate) by Yarrowia lipolytica W29 and NCYC 2904 for growth and lipids accumulation were studied. Yarrowia lipolytica grew efficiently in VFAs-based media, but lipids production was enhanced by the addition of co-substrates (glucose or glycerol) in batch cultures. A two-stage batch culture – growth phase on glucose, followed by VFAs addition, improved lipids accumulation. Lipids concentrations of 2.3 g·L−1 and 3.5 g·L−1 were obtained with this mode of operation, with addition of 18 g·L−1 VFAs, for Y. lipolytica W29 and NCYC 2904, respectively. For the first time, it was demonstrated that oxygen mass transfer is a crucial factor for lipids production by Y. lipolytica from VFAs. Intracellular lipids produced by Y. lipolytica strains were mainly composed by oleic and linoleic acids, similar to common vegetable oils, making these lipids suitable for biodiesel production. Moreover, margaric acid, which may improve biodiesel properties, was only detected in propionate medium. The strategies studied herein will contribute to the feasibility of using VFAs as low-cost feedstock for microbial lipids production by Y. lipolytica strains.

Determination of large microplastics: wet-sieving of dewatered digested sludge, co-substrates, and compost.

Dewatered digested sludge and compost may act as a conduit for microplastics (<5 mm) in terrestrial and subsequently aquatic systems. However, standardized methods for microplastics analyses are lacking. Thus, the aim is to demonstrate the applicability of wet-sieving as a way to quantify large microplastic particles (MPP, 1-5 mm) in dewatered digested sludge and compost. Additionally, we investigated the organic fraction of municipal solid waste, expired drinks and slaughterhouse waste used as co-substrate for anaerobic digestion at wastewater treatment plants (WWTP). Therefore, we collected samples from six WWTP and two biogas plants. These were then wet-sieved and potential MPP analysed via attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR). In dewatered digested sludge the amount of microplastics ranged from 0 to 326 MPP/kg TS (total solids) while compost contained 39-102 MPP/kg TS. Our results show that with 0-36 MPP/kg TS co-substrates are not necessarily a source of microplastics in WWTP. Furthermore, we found film to be the most abundant shape in the biogas plant samples, whereas, in WWTP samples film, fragments and fibers were detected the most. ATR-FTIR revealed that polyvinyl chloride, polyester, polypropylene, and polyethylene were the most abundant materials found across all samples.

Potentiality of municipal sludge for biological gas production at Soba Station South of Khartoum (Sudan)

Potentiality of municipal sludge for biological gas production at Soba Station South of Khartoum (Sudan)

Co-feeding spent coffee grounds in anaerobic food waste digesters: Effects of co-substrate and stabilization strategy

Anaerobic digestion of spent coffee grounds (SCG) is considered disadvantageous, particularly under mono-digestion conditions, owing to slow degradation and nutrient imbalance. This study investigated the effect of co-feeding of SCG at a low ratio into food waste (FW) digesters, with the aim to determine whether SCG can be effectively treated and valorized using the spare capacity of existing digesters. Duplicate reactors showed stable performance under FW mono-digestion conditions but manifested severe deterioration in three volume turnovers after co-feeding of SCG (FW:SCG at 10:1 on a volatile solids basis). The reactors failed to recover despite repeated interrupted feeding and stabilization, and Ulva was added (FW:SCG:Ulva at 20:2:1) for nutrient supplementation. The two reactors subjected to different stabilization strategies (i.e., timing and intervals of interrupted feeding) responded differently to Ulva co-feeding: one recovered and maintained stable albeit suboptimal performance, whereas the other failed. Furthermore, the microbial communities developed differently in the reactors.

Studies of the Effects of Co-substrates on Biodegradation Kinetics of 4-Chlorophenol Using Response Surface Methodology (RSM)

Studies of the Effects of Co-substrates on Biodegradation Kinetics of 4-Chlorophenol Using Response Surface Methodology (RSM)

Effect of cosubstrate on xylitol production by Debaryomyces nepalensis NCYC 3413: A cybernetic modelling approach

Abstract The growth of Debaryomyces nepalensis on mixed substrates in batch culture follows diauxic pattern of completely utilizing glucose during the first exponential growth phase, followed by an intermediate lag phase and a second exponential growth phase consuming xylose. The present study deals with the development of a cybernetic mathematical model for prediction of xylitol production in the presence of co-substrate. To experimentally validate the model, defined media supplemented with different concentration of co-substrate were tested and compared with production on single carbon source. High xylitol yield of 0.73 g g−1 was achieved when supplemented with 10 g L−1 of glucose in the xylose-rich media. The proposed model could adequately describe the diauxic growth, sequential utilization of substrates and production of xylitol under various ratio of co-substrate. The model could be used as a tool to assess the influence of co-substrate (glucose) concentration added to the media on xylitol production.

Carbon-to-nitrogen and substrate-to-inoculum ratio adjustments can improve co-digestion performance of microalgal biomass obtained from domestic wastewater treatment

ABSTRACTThis study comparatively evaluated the effect of co-substrates on anaerobic digestion (AD) and biochemical methane potential of wastewater-derived microalgal biomass, with an emphasis on carbon-to-nitrogen (C:N) and substrate-to-inoculum (S:I) ratios. A semi-continuous photobioreactor was inoculated with Chlorella vulgaris and the nutrient recovery potential was investigated. Derived microalgal slurry was subjected to AD in the absence and presence of co-substrates; model kitchen waste (MKW) and waste activated sludge (WAS). The results revealed that up to 99.6% of nitrogen and 91.2% of phosphorus could be removed from municipal wastewater using C. vulgaris. Biomethane yields were improved by co-digestion with both MKW and WAS. The maximum biomethane yield was observed as 523 ± 25.6 ml CH4 g VSadded−1, by microalgal biomass and MKW co-digestion in 50:50 ratio, at an initial chemical oxygen demand (COD) concentration of 14.0 ± 0.1 g l−1, C:N ratio of 22.0, and S:I ratio of 2.2. The observed biomethane yield was 80.7% higher than that of the mono-digestion. The highest improvement achieved by 50:50 co-digestion of microalgal biomass and WAS was 15.5%, with biomethane yield of 272 ± 11.3 ml CH4 g VSadded−1 at an initial COD concentration of 14.0 ± 0.1 g l−1, C:N ratio of 13.0, and S:I of 2.3.

Effect of bonding time on the microstructure and mechanical properties of Co/Sn/Cu joint

The bonding process of Co/Sn/Cu couple has been conducted at 270 °C. The microstructure evolution was observed. The spreading test of Cu/Sn–xCo and Co/Sn–xCu was conducted to explain the microstructure evolution of Co/Sn/Cu couple. The results showed that the main interfacial intermetallic compounds (IMCs) layer of Cu/Sn side of Co/Sn/Cu couple was (Cu, Co)6Sn5, as the dissolution of Co from Co substrate to solder layer. The (Cu, Co)6Sn5 IMCs layer only thickened slightly during bonding process as large amount of the (Cu, Co)6Sn5 IMCs layer dissociated into solder alloy layer. As the adsorbing effect of Co substrate on the dissociating (Cu, Co)6Sn5 IMCs, there was a thick (Cu, Co)6Sn5 IMCs layer covered on the surface of Co substrate at the early stage of bonding process. For longer bonding time (> 30 min), the (Co, Cu)Sn and (Co, Cu)Sn3 IMCs generated on the Co/(Cu, Co)6Sn5 interface as the diffusion of Sn atom from liquid solder alloy to Co/(Cu, Co)6Sn5 interface. The Co/Sn/Cu joint bonded for 60 min could work at the temperature of 300 °C. The shear strength of joints bonded for 20 and 30 min was approximate 45 MPa. The shear strength of joints bonded for a time more than 30 min declined gradually as the generation of (Co, Cu)Sn3 IMCs.

Effect of co-substrates on biogas production and anaerobic decomposition of pentachlorophenol

This study aims to examine the effect of different co-substrates on the anaerobic degradation of pentachlorophenol (PCP) with simultaneous production of biogas. Acetate and glucose were added as co-substrates to monitor and compare the methanogenic reaction during PCP degradation. During the experiment, a chemical oxygen demand (COD) removal efficiency of 80% was achieved. Methane (CH4) production was higher in glucose-fed anaerobic reactors with the highest amount of CH4 (303.3µL) produced at 200ppm of PCP. Scanning electron microscopy (SEM) demonstrates the high porous structure of anaerobic sludge with uniform channels confirming better mass transfer and high PCP removal. Quantitative real-time PCR (qPCR) revealed that methanogens were the dominating species while some sulfate reducing bacteria (SRBs) were also found in the reactors. The study shows that strategic operation of the anaerobic reactor can be a feasible option for efficient degradation of complex substrates like PCP along with the production of biogas.

Food Waste to Energy: An Overview of Sustainable Approaches for Food Waste Management and Nutrient Recycling.

Food wastage and its accumulation are becoming a critical problem around the globe due to continuous increase of the world population. The exponential growth in food waste is imposing serious threats to our society like environmental pollution, health risk, and scarcity of dumping land. There is an urgent need to take appropriate measures to reduce food waste burden by adopting standard management practices. Currently, various kinds of approaches are investigated in waste food processing and management for societal benefits and applications. Anaerobic digestion approach has appeared as one of the most ecofriendly and promising solutions for food wastes management, energy, and nutrient production, which can contribute to world's ever-increasing energy requirements. Here, we have briefly described and explored the different aspects of anaerobic biodegrading approaches for food waste, effects of cosubstrates, effect of environmental factors, contribution of microbial population, and available computational resources for food waste management researches.

The effects of co-substrate and thermal pretreatment on anaerobic digestion performance

ABSTRACTThe influence of anaerobic co-digestion of leachate and sludge with organic fraction of municipal solid waste (OFMSW) under mesophilic condition in three batch digesters of 5 L capacity has been studied. OFMSW was mixed with leachate and sludge at three different ratios. Experimental results illustrated that the digester with a ratio of 2000/2500 (leachate (mL) or sludge/OFMSW (mL)) had significantly higher performance. Furthermore, this study compared the performance of anaerobic digestion of different substrates with three different mixing ratios with and without thermal pretreatment at low temperature (65°C) in terms of biogas production, chemical oxygen demand (COD) elimination as well as hydraulic retention time. In addition, to predict the biogas yield and evaluate the kinetic parameters, the modified Gompertz model was applied. Based on the results, the maximum biogas yield from adding different leachate and sludge ratios to OFMSW was recorded to be 0.45 and 0.38 m3 kg−1 COD which was higher about 7% in comparison with co-digestion original OFMSW without thermal pretreatment. In addition, thermal pretreatment accelerated the hydrolysis step. Moreover, the total COD elimination was relatively stable in the range of 52–60% at all types of substrate mixtures. Also, the modified Gompertz model demonstrated a good fit to the experimental results.Abbreviations: AD: anaerobic digester; BOD: biochemical oxygen demand; COD: chemical oxygen demand; FAAS: flame atomic absorption spectroscopy; HS: high solids; HRT: hydraulic retention time; LS: low solids; MS: medium solids; OFMSW: organic fraction of municipal solid waste; TCD: thermal conductivity detector; TS: total solid; TSS: total suspended solids

Effect of Co-substrate on Degradation of Benzothiazole in MEC

Due to its persistence and bio-toxicity, benzothiazole (BTH) cannot be biodegraded efficiently. Recent work has shown that removal rates of biorefractory organics can be enhanced by the addition of co-substrates. In this work, ethanol, acetate, propionate and butyrate were added as co-substrates in order to promote the degradation of BTH in microbial electrolysis cell (MEC). By probing the changes in degradation rates of BTH in the presence of different co-substrates, it was observed that all the four co-substrates can enhance the BTH degradation in MEC, both the efficiency (E) and the rate (R). It was also found that acetate is more effective than others, which made the degradation efficiency of BTH up to 90% with acetate-C at 350 mg/L (measuring by the carbon content of co-substrate, the same below), within 6 h and the degradation rate of BTH arrived 0.001 2/(mg·h). The microbacteria in MEC have also been influenced by different co-substrates. This metabolism of the co-substrates enables the microbacteria on anode to generate ATP and thus grow to ensure the microbacteria activity. Therefore, this work showed that the addition of co-substrates such as acetate can be a novel and efficient approach for improving the elimination of BTH from wastewaters by MEC system.