Effect Of Total Solids Content Research Articles

Preparation, Optimization, and Characterization of Bovine Bone Gelatin/Sodium Carboxymethyl Cellulose Nanoemulsion Containing Thymol.

The aim of this study is to produce a biodegradable food packaging material that reduces environmental pollution and protects food safety. The effects of total solids content, substrate ratio, polyphenol content, and magnetic stirring time on bovine bone gelatin/sodium carboxymethylcellulose nanoemulsion (BBG/SCMC-NE) were investigated using particle size, PDI, turbidity, rheological properties, and zeta potential as evaluation indexes. The micro, structural, antioxidant, encapsulation, and release properties were characterized after deriving its optimal preparation process. The results showed that the nanoemulsion was optimally prepared with a total solids content of 2%, a substrate ratio of 9:1, a polyphenol content of 0.2%, and a magnetic stirring time of 60 min. SEM showed that the nanoemulsion showed a dense and uniform reticulated structure. FTIR and XRD results showed that covalent cross-linking of proteins and polysaccharides altered the structure of gelatin molecular chains to a more compact form but did not change its semi-crystalline structure. DSC showed that the 9:1 BBG/SCMC-NE had a higher thermal denaturation temperature and greater thermal stability, and its DPPH scavenging rate could reach 79.25% and encapsulation rate up to 90.88%, with excellent slow-release performance. The results of the study provide basic guidance for the preparation of stable active food packaging with excellent properties.

Effect of total solids content on anaerobic digestion of waste activated sludge enhanced by high-temperature thermal hydrolysis

Total solids (TS) content may provide a regulatory strategy for optimizing anaerobic digestion enhanced by high-temperature thermal hydrolysis, but the role of TS content is not yet clear. In this study, the effect of TS content on the high-temperature thermal hydrolysis and anaerobic digestion of sludge and its mechanism were investigated. The results showed that increasing the TS content from 2% to 8% increased the sludge solubility and methane production potential, reaching peak values of 26.6% and 336 ± 6 mL/g volatile solids (VS), respectively. With a further increase in TS content to 12%, the strong Maillard reaction increased the aromaticity and structural stability of extracellular polymer substances, decreasing sludge solubility to 18.6%. Furthermore, the decrease in sludge biodegradability and the formation of inhibitory by-products resulted in a reduction in methane production to 272 ± 4 mL/g VS. This article provides a new perspective to understand the role of TS content in the thermal hydrolysis of sludge and a novel approach to regulate the Maillard reaction.

Optimization and microbial community analysis for anaerobic digestion of water hyacinth (Eichhornia crassipes) with waste sludge at different solid contents and temperatures

In this study, optimum operating conditions for anaerobic digestion of water hyacinth (Eichhornia crassipes) with waste sludge was investigated at varying total solid (TS) content of the digestion solution (3.3%, 4.3%, 5.3%, 6.3%, 7.3% and 8.3%) and digestion temperature (35, 40, 45, 50 and 55 °C) to produce methane with high yield. The highest biogas yield reached experimentally was 163.2 mL/g TVS (with high CH4 content of 81.1 vol%) at 6.3% of TS content and digestion temperature of 35 °C. Kinetic parameters were estimated by using modified Gompertz, Cone and first-order kinetic models in which modified Gompertz model gave the lowest fitting errors (−1.0 to 3.7%). The effect of temperature on methane production rate was simulated by Ratkowsky model and optimum digestion temperature was found between 41.5 and 44 °C for maximum methane production at 6.3% TS. The experimental methane yields were 61.9–132.3 mL CH4/g TVS. The metagenomic sequencing was used to characterize microbial community structure of the anaerobic digestate at varying conditions and acetoclastic/hydrogenothrophic methanogenesis was equally dominated methane-producing pathways. The most abundant bacterial populations were found to be Proteobacteria, Firmicutes, Chloroflexi and Actinobacteria. Based on alpha diversity indices, it can be concluded that effect of digestion temperature on microbial richness and diversity was higher than the effect of TS content.

Hydrogen production from biomass through integration of anaerobic digestion and biogas dry reforming

Hydrogen is a clean fuel for heat and power generation and can serve as a feedstock for chemical synthesis. This study assesses the hydrogen production from biomass (e.g., cow manure) through integrating psychrophilic anaerobic digestion and dry methane reforming. For the first time, a rigorous model is developed for the low-temperature anaerobic digestion process by implementing the complex kinetics of the fermentation bioreactions. The produced biogas from the anaerobic digestion process is fed to the reforming process for hydrogen production. The kinetics of the dry methane reforming and water gas shift reactions over Co-Ni-Al2O3 catalyst are incorporated into the model. Validating the results of the proposed process using experimental data shows <5% relative deviation. The effects of total solids content, organic loading rate, hydraulic retention time, and digestate recirculation fraction on biogas and CH4 yield are investigated. The optimum values of operating parameters in the anaerobic digestion process as well as the dry methane reforming process are obtained. The process is designed to achieve the highest CH4-to-H2 conversion and the lowest energy consumption. A 48.07 kg/h biogas could produce 8.11 kg/h H2. The biomass-to-H2 process offers an energetic efficiency of 72.85%, revealing its superiority to similar processes, such as steam and auto-thermal reforming. The proposed process highlights a high potential for CO2 emission reduction (e.g., 398,736 t/y), compared to the direct biogas combustion for electricity production. Economic analysis shows that the cost of biogas-to-H2 production is 1.39 USD/kg H2 for a plant capacity of 45.5 kg/h H2.

Solid-state anaerobic co-digestion of organic fraction of municipal waste and sawdust: impact of co-digestion ratio, inoculum-to-substrate ratio, and total solids.

Municipal solid waste contains mainly organic wastes that can be a good source for anaerobic digestion. Solid-state anaerobic digestion is an affordable and suitable technique to mitigate the organic fraction of municipal solid waste (OFMSW). However, as the organic loading of OFMSW is high, co-digestion with other materials can improve the system's performance. This study aimed to investigate the performance of the co-digestion of OFMSW and sawdust and study the parameters affecting its performance. Based on the experiments, the optimum sawdust/OFMSW ratio was achieved 1:2 with the methane production of 0.3L/g VS. In addition, the inoculum-to-substrate ration (I/S) was investigated at 1:4, 1:2, 1:1, 2:1 ratios. The best result was obtained at 2:1 ratio with a total methane yield of 0.28 L/g VS. The results also indicated that I/S ratios less than 1:1 led to fatty acid accumulation and acidic pH condition. The effect of total solids content on the co-digestion process was also examined in this study. According to the results, as the total solids increased, the biomethane yield decreased while the biogas content increased.

Effect of total solids contents on the performance of anaerobic digester treating food waste and kinetics evaluation

The effects of total solids (TS) content on the performance of anaerobic digestion (AD) treating food waste (FW) and kinetic characteristics were investigated in mesophilic batch reactors. The results showed that FW could be digested normally in the AD system within the TS of 3%-30%. The volume methane yield of dry-AD increased by 5.2-10.6 times than that of wet-AD and the degradation time of unit substrate was shortened by 35%-71%. The system stability indicators of dry-AD, such as pH, VFA/TA, TAN and salt remain within the suppression threshold after digestion. dry-AD had obvious advantages. The kinetic analysis showed that ADM1 could be used to simulate the anaerobic digestion reactor of FW, and accurately simulated the methane production in different TS systems after calibrating. With the increase of TS, the hydrolysis and methane production showed a tendency to increase first and then decrease, but the decrease rate of hydrolysis was higher than that of methanogene. Increasing TS simultaneously weaken the hydrolysis rate and methanation rate, but the effect on the hydrolysis and acidification phase weaker. The ratio of the hydrolysis rate constant to the methanogenic Monod maximum specific absorption rate (khy/km_ac) was a new perspective to used to evaluate the balance between the hydrolysis stage and the methane production stage. The results show that the khy/km_ac ratio of the 15% TS and 20% TS experimental groups was close to 1. It can be speculated that the system TS between 15%-20% can be used as recommended value in anaerobic digestion engineering design to treat FW. Within this TS range, hydrolysis and methane production dynamics matching, the accumulation of inhibitors is also in a relatively moderate state in the threshold.

Effect of Total Solid Content of Lignocellulose Pulp and Paper Mill Sludge on Methane Production and Modeling

AbstractThis work studied the effect of total solids content on methane production potential from pulp and paper mill sludge and its kinetic modeling. The modified Gompertz, logistic function, and ...

Effect of total solids content on anaerobic digestion of poultry litter with biochar

Methane production via anaerobic digestion of poultry litter provides a pathway for energy production from an abundant waste product. Recent studies have shown the use of biochar (pyrolysed biomass) can decrease methane production lag times and increase peak daily yields from ammonia-stressed low-solids anaerobic digesters. Due to the variety of feedstocks and digester configurations used, research to date has not yet determined the effect of biochar addition as a function of the digester total solids content. This study shows the addition of biochar reduces the lag time by a greater percentage in the digesters with a higher total solids content. There was a 17%, 27% and 41% reduction lag time due to biochar addition at total solids contents of 5%, 10% and 20%, respectively. The peak daily methane yield increased by 136% at 10% total solids. There was no significant increase in the peak yield at 5% total solids, while there was a 46% increase at 20% total solids. Real-time PCR analysis confirms the Methanosaetaceae family, which is a key methanogen due to its ability to facilitate direct interspecies electron transfer while attached to biochar, preferentially attaches to biochar. Furthermore, this research shows the attachment of the Methanosaetaceae family, does not decrease with increasing total solids content. A potential negative effect of biochar addition, a reduced volumetric efficiency, can be negated by using a shorter retention time. This new understanding will help to improve predictions of the impact of biochar addition for new digester designs operating in semi-solids and high-solids conditions.

Preparation and characterization of natural rubber bio-based wood adhesive: effect of total solid content, viscosity, and storage time

Natural rubber (NR) grafted by methyl methacrylate (MMA) was used to produce bio-based wood adhesive. The effect of total solid content (%TSC) at 55, 57, and 60%, represented as 55NR-g-MMA, 57NR-g-MMA, and 60NR-g-MMA, respectively, and the effect of storage time on lap shear strength were investigated. It was found that contact angle sharply decreased from 95° for NR to approximately 65° for all of NR-g-MMAs. Because the MMA groups were incorporated into various NR-g-MMA samples and the highest relative amount of grafted MMA was obtained by 57-NR-g-MMA which is determined by peaks intensities ratio between wave number at 1725 (C=O stretching) and 1450 (CH2 stretching), investigated by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR). These influences resulted in an increase in storage modulus (E′), whereas tanδ was decreased as compared to that of NR, characterized by dynamic mechanical analyzer (DMA). In addition, the apparent viscosity performed by plate-and-plate rheometer trended to increase with total solid content and storage time. However, the highest lap shear strength was achieved by 57NR-g-MMA. It means that the lap shear strength was not only governed by viscosity as well as total solid content, but the amount of grafted MMA also plays an important role.

Effect of process parameters on enhanced biohydrogen production from tequila vinasse via the lactate-acetate pathway

In this study, a lactate-type fermentation entailing the consumption of lactate and acetate (lactate-acetate pathway) is proposed to deal with lactic acid bacteria (LAB) inhibition during the production of biohydrogen (bioH2) from tequila vinasse. The effects of total solids content, substrate concentration, nutrient formulation and inoculum addition on bioH2 production performance were investigated. Batch experiments were performed in a 3-L completely mixed reactor at 35 °C and pH 6.5–5.8. The lactate-acetate pathway mediated consistent bioH2 production which was influenced by inoculum addition followed by substrate concentration, nutrient formulation and solids content. Maximum bioH2 production rate (225 NmL/L-h) and yield (124 NmL/g VSadded) were achieved by removing suspended solids and enhancing nutrient content, respectively. Illumina sequencing-based analysis revealed a dominance of Clostridium in the inoculum, which together with LAB and acetic acid bacteria shaped a keystone cluster for avoiding LAB inhibition while ensuring consistent bioH2 production performance.

Effect of total solid content and pretreatment on the production of lactic acid from mixed culture dark fermentation of food waste

Food waste landfilling causes environmental degradation, and this work assesses a sustainable food valorization technique. In this study, food waste is converted into lactic acid in a batch assembly by dark fermentation without pH control and without the addition of external inoculum at 37 °C. The effect of total solid (TS), enzymatic and aeration pretreatment was investigated on liquid products concentration and product yield. The maximum possible TS content was 34% of enzymatic pretreated waste, and showed the highest lactic acid concentration of 52 g/L, with a lactic acid selectivity of 0.6 glactic/gtotalacids. The results indicated that aeration pretreatment does not significantly improve product concentration or yield. Non-pretreated waste in a 29% TS system showed a lactic acid concentration of 31 g/L. The results showed that enzymatic pretreated waste at TS of 34% results in the highest production of lactic acid.

Effects of Storage Conditions, Total Solids Content and Silage Additives on Fermentation Profiles and Methane Preservation of Cattle Manure Before Anaerobic Digestion

The impacts of storage conditions, total solids content and silage additives were investigated at laboratory scale for cattle manure during up to 120 days. Wheat straw was used as co-substrate in the study of the effects of total solids content. Glucose and starch were used as model molecules of sugar-rich co-substrates. Single-handedly cattle manure lost 37% of its original methane potential after 120 days of anaerobic storage. This was essentially caused by the low total solids content and by the absence of water soluble carbohydrates in the feedstock. Wheat straw addition decreased moisture content and enabled cattle manure stabilization for a pH of 6.0. In contrast, extensive heterofermentative lactic acid bacteria fermentation occurred during co-ensiling with glucose and the pH quickly dropped to values below 4.0. Starch was used as substrate for fermentation but its hydrolysis limited bacterial activity and acidification. Finally, all the three co-substrates led to minimal methane potential losses after 120 days of storage. Co-ensiling will improve the energy efficiency of agricultural biogas plants that use stored cattle manure as feedstock.

Effect of total solids content on biohydrogen production and lactic acid accumulation during dark fermentation of organic waste biomass

Production of biohydrogen and related metabolic by-products was investigated in Solid State Dark Fermentation (SSDF) of food waste (FW) and wheat straw (WS). The effect of the total solids (TS) content and H2 partial pressure (ppH2), two of the main operating factors of SSDF, were investigated. Batch tests with FW at 10, 15, 20, 25 and 30% TS showed considerable effects of the TS on metabolites distribution. H2 production was strongly inhibited for TS contents higher than 15% with a concomitant accumulation of lactic acid and a decrease in substrate conversion. Varying the ppH2 had no significant effect on the conversion products and overall degradation of FW and WS, suggesting that ppH2 was not the main limiting factor in SSDF. This study showed that the conversion of complex substrates by SSDF depends on the substrate type and is limited by the TS content.

Effct of Solid Content and pH on Biogas Production From Organic Fraction Municipal Solid Waste

The increasing demand for energy and the constraints on environmental aspects motivate theresearch on municipal solid waste to be an environmentally friendly source of renewable energy. Thereforeusing the organic fraction of municipal solid household waste in an anaerobic digester to produce biogas anda digestate which can be used safely as fertilizer. In this study, three reactors of two-liter volume are used toinvestigate the effect of total solid content (10%, 15%, 20%) and pH on the produced amount of biogas. Theresults revealed that a lower percentage of solid content yields the highest amount of biogas and the pH below6.0 will inhibit biogas production. The percentage of methane from the 10% reactor was 50.2 % of the gasproduction

Effects of total solids content on performance of sludge mesophilic anaerobic digestion and dewaterability of digested sludge

The role of total solids (TS) content on sludge mesophilic anaerobic digestion (AD) was investigated in batch reactors. A range of TS below 10% was evaluated with two replicates. The volumetric biogas production rate (VBPR) increased with increasing initial TS. On day 5, VBPR increased from 133.2±11.2mLL−1d−1 at TS 2% to 1111.7±58.1mLL−1d−1 at TS 10%. The ultimate biogas yield (P) firstly increased and then decreased with the increasing TS. The greatest P was 246.8mLg−1-VSadded at TS 8%. The corresponding free ammonia nitrogen (FAN) and total ammonia nitrogen (TAN) were 84.0±16.1 and 1163.0±108.6mgL−1, respectively. Normalized capillary suction time (NCST) and solid content of thickened sludge obtained by centrifuging sludge increased with increasing TS. On day 49, NCST were 1.2±0.2 (TS=2%) and 13.2±1.1 (TS=10%)sg−1-TS. Meanwhile, solid content of thickened sludge was 7.5±0.5 (TS=2%) and 15.4±0.0% (TS=10%). In summary, high VBPR and dewatering effects were obtained after TS content optimization.

Volatile fatty acid production from spent mushroom compost: Effect of total solid content

To improve volatile fatty acids (VFAs) production from spent mushroom compost (SMC), the effect of total solid (TS) content was studied. The protein and polysaccharide solubilization, ammonium (NH4+-N) and phosphate (PO43−-P) release, and VFAs production were analyzed. Results showed that the optimal fermentation time was 4 day for VFAs production, longer fermentation time led to VFAs consumption and methane production. Within the TS range from 6% to 18%, a TS of 15% was the optimal for VFAs production, the highest VFAs concentration reached 2781 mg/L, and acetate and propionate acids accounted for about 71% of total VFAs. In addition, the maximum concentration of soluble protein and polysaccharide reached approximately 1648 mg/L and 1394 mg/L, respectively. The NH4+-N and PO43−-P release was in a range of 2.11–7.59 mg/gVS and 0.26–1.13 mg/gVS, respectively. If the NH4+-N and PO43−-P can be removed, the application of VFAs utilization might be significantly enhanced.

Effects of total solids content on waste activated sludge thermophilic anaerobic digestion and its sludge dewaterability

The role of total solids content on sludge thermophilic anaerobic digestion was investigated in batch reactors. A range of total solids content from 2% to 10% was evaluated with two replicates. The lowest inhibitory concentration for free ammonia and total ammonia of sludge thermophilic anaerobic digestion was 110.9–171.4mg/L and 1313.1–1806.7mg/L, respectively. The volumetric biogas production rate increased with increasing of total solids content, but the corresponding biogas yield per gram volatile solid decreased. The result of normalized capillary suction time indicated that the dewaterability of digested sludge at high total solids content was poor, while solid content of sediment obtained by centrifuging sludge at 2000g for 10min increased with increasing of total solids content of sludge. The results suggest that thickened sludge mixed with dewatered sludge at an appropriate ratio could get high organic loading rate, high biogas yield and adequate dewatering effort.

Effect of total solids content on giant reed ensilage and subsequent anaerobic digestion

The effect of total solids (TS) content on giant reed ensilage and subsequent methane production by both liquid anaerobic digestion (L-AD) and solid-state anaerobic digestion (SS-AD) was investigated. Minimal loss of TS (about 1%), cellulose (1.2–2.4%), and hemicellulose (2.9–4.7%) was observed after 30 days of giant reed ensilage at TS contents from 25% to 40%. Ensilage with a TS content of 25% showed higher consumption of water soluble carbohydrates and extractives than those with TS contents of 30–40%, which was consistent with its higher production of organic acids and lower pH. Compared to non-ensiled giant reed, ensiled giant reed achieved up to 15% higher methane yield during AD. Ensiling giant reed at a TS content of 25% resulted in a lower glucose yield during enzymatic hydrolysis and lower methane yield during the subsequent AD, compared with ensiling it at TS contents of 30–40%. Compared to L-AD, SS-AD of non-ensiled or ensiled giant reed showed 12–18% lower methane yields, but about 2 times higher volumetric methane productivities.

Water Sorption and Water Plasticization Behavior of Vacuum Dried Honey

The present study investigated effects of total solids content of honey maltodextrin systems and the component ratio on water sorption isotherm and water plasticization behavior of the vacuum-dried solids. The Guggenheim, Anderson, and de Boer model fitted well to the water sorption data with monolayer water contents over the range of 4.8–6.2 g water/100 g of solids. Water plasticization of the powder followed the Gordon–Taylor equation, with the Tg of dry solids of 30–43°C depending on composition. The critical water content of dried honey at 25°C was lower than the monolayer water content. A maltodextrin ratio more than 50% decreased water plasticization sensitivity to the highest extent.

Effect of total solids content on methane and volatile fatty acid production in anaerobic digestion of food waste.

This work investigates the role of the moisture content on anaerobic digestion of food waste, as representative of rapidly biodegradable substrates, analysing the role of volatile fatty acid production on process kinetics. A range of total solids from 4.5% to 19.2% is considered in order to compare methane yields and kinetics of reactors operated under wet to dry conditions. The experimental results show a reduction of the specific final methane yield of 4.3% and 40.8% in semi-dry and dry conditions compared with wet conditions. A decreasing trend of the specific initial methane production rate is observed when increasing the total solids concentration. Because of lack of water, volatile fatty acids accumulation occurs during the first step of the process at semi-dry and dry conditions, which is considered to be responsible for the reduction of process kinetic rates. The total volatile fatty acids concentration and speciation are proposed as indicators of process development at different total solids content.