Increase In Gas Production Research Articles

Proton exchange membrane water electrolysis at high current densities: Response time and gas‐water distribution

AbstractUnderstanding the distribution of oxygen in proton exchange membrane water electrolysis (PEMWE) is crucial for improving electrolysis efficiency and gas removal. In this study, we developed a two‐dimensional (2D) transient model that couples the Euler–Euler multiphase model with electric potential equations to investigate two‐phase flow in PEMWE. Our simulation reveals that the system's response time initially decreases and then increases with current density, indicating longer response times at high current densities. Modifying the wetting properties of the porous transport layer (PTL) affects gas removal at low gas holdup, resulting in a maximum 15% decrease in gas holdup. However, at high gas holdup, the flow field in the channel predominantly governs bubble removal, making changes in PTL wetting properties less influential. With increasing gas production rate, an inverse gradient distribution of gas saturation appears, leading to uneven gas saturation and hindering efficient oxygen removal. This non‐uniform gas saturation adversely affects electrolysis performance.

Water Shutoff With a Thixotropic Treatment in Offshore Well Increases Gas Production

_ This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 209889, “A Successful Water Shutoff Using a Thixotropic Treatment in a Subhydrostatic and Highly Aromatic Well Results in Increased Gas Production of 30% and Reduced Water Production of 63% in Vietnam,” by Tuanangkoon Daohmareeyor, Tran Thang Nguyen, and Reawat Wattanasuwankorn, Halliburton, et al. The paper has not been peer reviewed. _ An offshore operator in Vietnam faced high water production in a subhydrostatic and highly aromatic gas well. In addition to low productivity, the high water cut also strained the water-treatment facility. Previous treatment attempts to shut off the high-water-producing zones have been unsuccessful because of challenging well conditions. A customized solution using a thixotropic organically crosslinked polymer (TOCP) with extensive laboratory testing was found to be the most suitable treatment design for this well. The new placement technique provided prevention of losses to the depleted zones. The thixotropic treatment provided higher viscosity when pumping stopped, allowing the polymer to seal off at the target zone. Introduction Excessive water production in mature wells is a major challenge for oil and gas operators worldwide, causing numerous economic issues for hydrocarbon production. In this case, the operator faced concerns with handling the water at the production facility, which had almost reached its capacity limit and would soon result in well abandonment. Furthermore, the well discussed in the complete paper was one of the highest-producing gas wells on the platform. The trend of gas production in this well was decreasing year over year, however, and the previous chemical water-shutoff treatment was not successful because of reasons that included the following: - The highly depleted formation created difficulties for well-intervention activities and treatment placement. - A complex well-completion setup was not ideal for well intervention, especially for mechanical isolation applications. - High aromatic content from the reservoir created incompatibility with mechanical isolation packer elements, risking operational failure. To achieve a shutoff objective, prejob considerations should include proper candidate selection, root-cause investigation, placement selection, tailored treatment design, and risk-mitigation planning, all of which are important factors of a successful operation. The complete paper presents the design and operational execution to serve as a guideline for future wells with similar issues. The operation’s objective was to shut off the top interval (Interval A) of five intervals in the well to reduce water production and increase gas production.

Characteristics of photothermal transfer and biochemical reaction in up-flow direct absorption hydrogen reactor with embedded ribs

The anaerobic fermentation process of microbial community is a promising method to treat wastewater with high ammonia nitrogen, but it needs to provide suitable temperature. An innovative direct absorption anaerobic reactor was established to reduce the temperature fluctuation of biogas slurry by adding ribs to ensure the high efficiency and stability of anaerobic fermentation process. The effects of flow rate and number of ribs on gas production in the process of photothermal conversion and anaerobic fermentation were analyzed by numerical simulation. The results show that the addition of ribs can effectively reduce temperature fluctuation and increase gas production. Compared with 2269.7 mL/L gas production and temperature fluctuation of up to 8 K without ribs, the gas production increased by 863.1 mL/L and decreased to 0.1624 K when the number of ribs was 9, respectively. Simultaneously, a curve was fitted according to gas production to predict the best working conditions.

Insight into the effect of chemical structure for microbial lignite methanation

The chemical structure of lignite plays a fundamental role in microbial degradation, which can be altered to increase gas production. In this study, the structural changes in lignite were analyzed by conducting pretreatment and biomethane gas production experiments using crushing and ball milling processes, respectively. The results revealed that different particle size ranges of lignite considerably influence gas production. The maximum methane yield under both treatments corresponded to a particle size range of 400–500 mesh. The gas production after ball milling was higher than that after crushing, irrespective of particle size. Compared with lignite subjected to crushing, that subjected to ball milling exhibited more oxygen-containing functional groups, less coalification, more disordered structures, and small aromatic ring structures, demonstrating more unstable properties, which are typically favorable to microbial flora for the utilization and degradation of lignite. Additionally, a symbiotic microbial community comprising multiple species was established during the microbial degradation of lignite into biogas. This study provides new insights and a strong scientific foundation for further research on microbial lignite methanation.

Effectiveness of herbal plants on rumen fermentation, methane gas emissions, in vitro nutrient digestibility, and population of protozoa.

Herbal plants have the potential to reduce the population of metagonic bacteria and protozoa due to the bioactive compound contained in herbal plants. This study aimed to evaluate the effect of herbal plant supplementation on rumen fermentation characteristics, methane (CH4) gas emissions, in vitro nutrient digestibility, and protozoan populations. This study consisted of two stages. Stage I involved determining the potential of herbal plants to increase total gas production (Orskov and McDonald methods) and reduce the protozoan population (Hristov method). Three potential herbs were selected at this stage and used in Stage II as supplements in the palm kernel cake (PKC)-based diet (30% herbal plants + 70% PKC). Proximate and Van Soest analyses were used to determine the chemical composition. In vitro dry matter digestibility (IVDMD), organic matter (IVOMD), and rumen fermentation characteristics were determined using Theodorous method. Conway microdiffusion was used to determine ammonia concentration (NH3). Gas chromatography was used to determine the total and partial volatile fatty acid production. The results of the first stage showed that seven herbal plants (Moringa oleifera, Rhodomyrtus tomentosa, Clerodendron serratum, Curcuma longa Linn., Urena lobata, Uncaria, and Parkia timoriana) significantly differed in terms of total gas production (p < 0.05). Herbal plants can increase gas production and reduce protozoan populations. The highest total gas production was observed using P. timoriana, M. oleifera, and C. longa Linn. Moringa oleifera plants were the most effective in lowering protozoa population. In Stage 2, the supplementation of herbal plants in PKC-based-diet significantly increased IVDMD, that was ranged from 56.72% to 65.77%, IVOMD that was ranged from 52.10% to 59.54%, and NH3, that was ranged from 13.20 mM to 17.91 mM. Volatile fatty acid partial and total gas production potential and CH4 gas emissions were also significantly different from those of the control (p < 0.05). Supplementation of M. oleifera, C. longa Linn., and P. timoriana in ruminant diet effectively increased total gas production, IVDMD percentage, and IVOMD, and reduced CH4 gas emissions and protozoa populations during rumen fermentation.

Application of Ammoniation Pretreatment in Anaerobic Digestion of Straw

Straw is a widely available and highly renewable biomass resource with good utilization value. However, its dense structure is not conducive to methane production during anaerobic fermentation and requires pretreatment. To achieve high-value conversion, pretreatment technologies can effectively destroy the rank structure of straw and increase gas production. Ammoniation pretreatment has unique advantages in pretreating straws. This article reviews the ammoniation pretreatment mechanism, the impact of ammoniation pretreatment parameters on anaerobic fermentation, and ammoniation pretreatment technology, providing a reference for the ammoniation pretreatment of straw.

Gas Production Enhancement by Horizontal Wells with Hydraulic Fractures in a Natural Gas Hydrate Reservoir: A Thermo-Hydro-Chemical Study

It is a complicated thermo-hydraulic-chemistry (THC) coupling process to produce methane from a natural gas hydrate (NGH) reservoir. To meet the commercial exploitation of NGH, hydraulic fracturing has been proposed to increase gas production. In this study, a THC coupling method was set up to simulate the NGH production process. Based on this coupling method, a series of three-dimensional models were built to model the NGH production by the depressurization method through a combination of horizontal well and hydraulic fracturing. The influences of factors (fracture length, fracture aspect ratio, fracture number, fracture interval, production pressure, and instinct permeability anisotropy) on the stimulation efficiency were analyzed. The results indicated: (i) the combination of horizontal well and hydraulic fracturing can greatly improve gas production comparing with only the horizontal well and the long-term folds of increase (FOI) > 5. (ii) The stimulation efficiency increases with the increase of fracture length. Properly increase the fracture number and/or the fracture interval can obviously increase the stimulation efficiency of fracturing and extend the period of first stage of FOI (FOI ≥ 10). (iii) For the same fracture width, the fracture section area is the most significant geometry factor, affecting the gas production improvement in hydraulic fracturing. When the fracture section area is specified, the effect of fracture aspect ratio on FOI is neglectable. (iv) The FOIs are almost the same when the production pressure changes under the same fracture parameter. (v) There exists an obvious interference between adjacent fractures, which increases with the increase of fracture half-length and/or the aspect ratio between the half fracture length and half fracture height under the same fracture interval. This work provides theoretical suggestions for hydraulic fracturing of horizontal well in NGH production.

Amilase exógena aumenta a produção de gases e melhora a cinética de digestão ruminal in vitro de grãos de sorgo e milho

ABSTRACT The aim of this study was to evaluate the effect of exogenous amylase on gas production, in vitro dry matter digestibility (IVDMD), and in vitro digestion kinetics of sorghum (Sorghum vulgaris) and two corn hybrids of different grain textures. Ruminal fluid was collected from two rumen-fistulated cows receiving or not exogenous amylase (0.7g kg-1 of dry matter (DM basis)), provided to achieve 396 kilo Novo units kg-1 for amylase activity (DM basis). Gas production was measured after 1, 3, 6, 9, 12, 15, 18, 21, 24, 30, 36, 42 e 48 hours of incubation. Amylase increased gas production (mL) by 5.4%. Corn hybrids have higher in vitro dry matter digestibility than sorghum. Exogenous amylase increased the potential of gas production (A) (P=0.01). There was an effect of hybrid for IVDMD (P&lt;0.01). The addition of exogenous amylase increases the in vitro gas production, improves fermentation kinetics, and increases the production of the ammonia nitrogen of corn and sorghum grains, but does not affect in vitro and dry matter digestibility or the short-chain fatty acids production.

Study on Energy Conversion Efficiency and Structure Optimization of the Multorifices Nozzle for Radial Jet Drilling

Underground gas storage (UGS) is a crucial method for mitigating seasonal fluctuations in natural gas consumption. However, in China, UGS is primarily achieved through the conversion of abandoned gas reservoirs with limited storage capacity. Radial jet drilling (RJD) is an effective technology for the secondary development of depleted reservoirs. The multiorifice nozzle is a critical component that can efficiently break rock and create radial holes to increase gas production. In this study, we investigate the impact of nozzle structure on energy conversion efficiency through numerical simulations and experiments. Additionally, we design a swirling multiorifice nozzle and verify its effectiveness in field applications. Our findings indicate that the nozzle pressure drop and vorticity are primarily generated at the acute angle of the orifices. The number of forward orifices is directly proportional to energy loss, while the discharge coefficient and hydraulic performance initially increase and then decrease. Swirling multiorifice nozzle have fewer backward orifices, so they have less energy loss and a larger discharge coefficient. It has achieved better rock-breaking results in field applications. In conclusion, this study provides theoretical guidance and technical support for the secondary development of gas storage.

Optimization of substrate mixing ratios for the anaerobic digestion of chicken manure and slaughterhouse waste: a case study of Irvine’s Zimbabwe (Pvt) Ltd, Zimbabwe

This study investigated the biogas potential of co-digesting chicken manure (CM) and slaughterhouse waste (SW) at Irvine’s Zimbabwe (Pvt) Ltd farm. Four different mixes of CM to SW as a percentage of total solids (TS) as follow: Mix 1 (100%: 0%); Mix 2 (67%: 33%); Mix 3 (33%: 67%) and Mix 4 (0%: 100%) were considered for co-digestion using cow dung as inoculum. The mixes were characterised in terms of carbon to nitrogen (C/N) ratio, chemical oxygen demand (COD), pH, TS, and volatile solids (VS). After 15 days of digestion, Mix 1 produced the highest biogas of 51 mL/gTS (24.4 m3/m3 feedstock) with a methane content of 30.2 mL/gTS (59.1%). The COD, pH, and TS values for the mixes after digestion ranged from 11,250 mg/L (Mix 1) to 25,000 mg/L (Mix 4), 5.54 (Mix 1) to 6.48 (Mix 4) and 11.5% (Mix 4) to 14.7% (Mix 2), respectively. Unlike findings from other studies that suggest that co-digestion increases gas production, mono-digestion of CM had the highest biogas potential and produced the most stable sludge. Therefore, mono-digestion of CM can be used for biogas production at Irvine’s Zimbabwe (Pvt) Ltd farm.

Community Synergy of Lactic Acid Bacteria and Cleaner Fermentation of Oat Silage Prepared with a Multispecies Microbial Inoculant.

To investigate community synergy of lactic acid bacteria (LAB) and cleaner fermentation of oat silage, oat silages were prepared with or without (control) commercial LAB inoculants LI1 (containing Lactiplantibacillus plantarum, Lentilactobacillus buchneri, Lacticaseibacillus paracasei, and Pediococcus acidilactici) and LI2 (containing Lactiplantibacillus plantarum and Lentilactobacillus buchneri). The microbial community, LAB synergy, and cleaner fermentation were analyzed at 1, 3, 6, 15, 35, and 90 days of ensiling. The LAB inoculant improved fermentation quality, with significantly (P < 0.05) lower pH, ammonia nitrogen content, and gas production and higher lactic acid and acetic acid contents than those of the control. Enterobacteriaceae was the main bacterial community in early stage of fermentation, which utilizes sugar to produce CO2 gas, causing dry matter (DM) and energy loss. As fermentation progressed, the microbial diversity decreased, and the microbial community shifted from Gram-negative to Gram-positive bacteria. The inoculation of multispecies LAB displayed community synergy; Pediococcus acidilactici formed a dominant community in the early stage of fermentation, which produced an acid and anaerobic environment for the subsequent growth of Lentilactobacillus and Lacticaseibacillus species, thus forming a LAB-dominated microbial community. The predicted functional profile indicated that the silage inoculated with LI1 enhanced the carbohydrate metabolism pathway but inhibited the amino acid metabolism pathway, which played a role in promoting faster lactic acid production, reducing the decomposition of protein to ammonia nitrogen, and improving the fermentation quality of silage. Therefore, oat silage can be processed to high-quality and cleaner fermented feed by using an LAB inoculant, and LI1 showed better efficiency than LI2. IMPORTANCE Oat natural silage is rich in Enterobacteriaceae, increasing gas production and fermentation loss. Lactic acid bacteria interact synergistically to form a dominant community during ensiling. Pediococci grow vigorously in the early stage of fermentation and create an anaerobic environment. Lactobacilli inhibit the harmful microorganisms and result in cleaner fermentation of oat silage.

Hydraulic fracturing performance analysis by the mutual information and Gaussian process regression methods

In shale gas production rate prediction, data are commonly acquired through simulations, which offer benefits but cannot fully predict the outcome of real engineering projects. This paper applied a Gaussian process regression (GPR) model, which was trained on the geological and field data from 175 wells in the Fuling gas field, China. GPR was chosen because this method can be suitably applied to a small dataset. To improve the accuracy, reduce the computational consumption, and increase the interpretability of the model, the mutual information method was used for feature selection after Pearson coefficient analysis. Based on comparison of the GPR, random forest and artificial neural network models, GPR achieved the best performance with the mutual information feature selection method, exhibiting R2 values of 0.71 and 0.68 for the training and test datasets, respectively. After model training, the model applied the Shapley additive explanation (SHAP) value method. The results indicate that geological factors dominate the gas production rate in Fuling, China. The volume of fluid loss could exert a negative impact on production rates and increase the consumption of 40–70 mesh proppant could increase gas production in Fuling.

Increasing Gas Production of Continuous Freeze-Thaw Hydrate Deposits Based on Local Reservoir Reconstruction

The fracturing technology for increasing gas production based on hydrate reservoir reconstruction has been proven to have the application prospect of hydrate production. The main content of this work is to study the influence mechanism between multiple production wells after fracturing the reservoirs around horizontal wells. Simulation results indicated that the gas production rates and cumulative volume of released gas by using hydraulic fracturing were both higher than that by using the traditional depressurization method. The average gas-to-water ratio in this work has broken through the technical bottleneck of exploiting hydrate only by the traditional depressurization method. After the rock matrix around the horizontal well was fractured, the permeability of the reservoir in the fracturing area would be increased; thus, the propagation distance of pressure drop would be promoted. In addition, the penetration of the hydrate decomposition area between horizontal production wells was conducive to promoting the flow of decomposed gas and water to production wells. Besides, the hydraulic fracturing method to increase the permeability of the reservoir around the production well is very effective for the gas production of low-permeability natural hydrate deposits. The best distance between production wells was recommended to be 45~60 m, and it was recommended to provide appropriate heat in the area between the two wells to accelerate the decomposition of hydrate.

Wyznaczanie parametrów kinematycznych agregatu sprężarkowego w zastosowaniach z LPG

The collection and transportation of low-pressure gas released into the atmosphere from the oil fields is important in increasing gas production. This issue, which differs in its actuality, has both economic and pollution preveniton benefits. One such project, led by the UN Development Fund, was successfully implemented in the city of Siyazan, Azerbaijan. An electrically driven compressor unit of NQK-7/1-5 type with two oscillating cylinders is commonly used for such work. On visual inspection of the compressors undergoing repair, it was found that the seals in the pneumatic part and the elements of the cylinder-piston group are completely out of order, the gear teeth in the transmission part are broken, worn, the bearings are destroyed, the belts are torn, etc. Compressors sent for repair are almost always reassembled. A structural-kinematic analysis of the compressor installation was carried out to find out the causes of the existing malfunctions. For this purpose, a kinematic diagram of the conversion mechanism of the compressor – a slider-crank linkage mechanism was drawn up using the method of closed contours from projection equations relative to the X and Y axes, and based on the condition that the rotation angles of the piston and cylinder axes are equal, the instantaneous rotation angle, angular velocity and angular acceleration of the cylinder rotation, as well as instantaneous values of displacement, speed and acceleration of the piston inside the cylinder were found. It was shown that the designer's decision on the selection of the design scheme and determination of the product dimensions, which are one of the main issues in the design of the mechanism, should be made based on the results of the kinematic and dynamic analysis.

Biogas Production from Steam-Exploded Maize Stover: Results from Continuous Anaerobic Tank Bioreactor Tests

Steam explosion pretreatment of lignocellulosic biomass presents a promising technology for agricultural residues before anaerobic degradation. This study aimed to assess biogas production in continuously stirred tank reactors using steam-exploded maize stover mono-digestion. The continuous digestion tests were carried out in four fermenters with a capacity of 150 L under mesophilic and thermophilic conditions. Maize stover was pretreated at 173 °C for 15 min. Four different organic loading rates (OLR) were tested, the biogas and methane production rate was monitored, and parameters such as dry matter (DM), volatile solids (VS), pH, and C:N were analyzed. The results of the tests showed that using steam-exploded maize stover in a continuous system over the range of an OLR from 1.0 to 3.5 kg VS m–3 d–1 is feasible with nitrogen as an additive only. The maximum methane yield, 637 LN m–3 d–1, was measured under thermophilic conditions with an OLR of 3.5 kg VS m–3 d–1. The trend of an increased gas production rate with an increasing OLR was observed over the range of the applied OLRs, although the average gas yield in the thermophilic mode was higher than it was in the mesophilic one.

Geomechanical Characteristics and Stimulation of Dibei Deep Tight Sandstone Reservoirs in the Kuqa Depression of Tarim Basin

Facing the problem of increased production of deep tight gas reservoirs, this study takes the Dibei gas reservoir in Tarim Basin as an example, carries out geomechanical research, and reveals the rock mechanical properties, in situ stress, and fracture characteristics of the tight reservoir. From the perspective of the in situ stress field and the effectiveness of fractures, the study reveals their impacts on reservoir quality, wellbore stability, and fracturing networks. The results show that the in situ stress and the effectiveness of fracture mechanics under its control have obvious control over the production capacity in the Dibei gas reservoir. The positions and intervals with low in situ stress, high fracture density, and fracture effectiveness are often favorable parts. A directional well has the dual advantages of overcoming reservoir heterogeneity and safety and stability. Understanding the geomechanical characteristics can quantitatively optimize the best wellbore trajectory, reduce the difficulty of fracturing from the source of well location deployment, improve the efficiency of hydraulic fracturing, and then realize the stimulation of gas reservoirs. In addition, the favorable borehole trajectory considers both the sweet spot penetration and borehole wall stability, which will reduce the difficulty of fracturing and is conducive to the efficient stimulation of tight gas reservoirs. Geomechanics research has built an integrated bridge between geology and engineering, which plays a significant role in increasing gas production.

Study on Monitoring Reservoir Gas Density by Pulsed Neutron Logging

In mature multilayer gas reservoirs, it is a common problem to evaluate whether a potential reservoir is still productive after casing. Monitoring of unproduced or developing gas formations can guide production action plans. Intervention in unperforated zones with high gas density can increase gas production, whereas intervention in zones with low gas density is uneconomical. An RPM instrument stratum model was established by using the Monte Carlo method in this study. The model was used to simulate the response characteristics of pulsed neutron logging in a sandstone reservoir with 100% gas saturation to different reservoir gas densities, formation porosity, and shale content. The data obtained from the simulation were interpolated to construct a capture gamma ratio plate and a nonbounce gamma ratio plate. Using the constructed chart, the gas density of the reservoir can be quantitatively calculated, and then, the recovery value of the potential gas layer can be evaluated.

Effect of Methionine Hydroxy Analog on Hu Sheep Digestibility, Rumen Fermentation, and Rumen Microbial Community In Vitro

This experiment was conducted to evaluate the effects of a methionine hydroxy analog (MHA) on in vitro gas production, rumen fermentation parameters, and rumen microbiota. Two different MHA, 2-hydroxy-4-(methylthio) butanoic acid isopropyl ester (HMBi) and the calcium salt of the hydroxy analog of methionine (MHA-Ca), were selected for in vitro experiments. The treatments were the Control group (0% of MHA), HMBi group (2%HMBi), and MHA-Ca group (2%MHA-Ca). Dry matter digestibility was measured after 12 h and 24 h of fermentation, and fermentation parameters and microbial composition were analyzed after 24 h. HMBi and MHA-Ca showed increased (p = 0.001) cumulative gas production in 3 h. The total volatile fatty acids, microbial protein (MCP) concentration, acetate, and acetate to propionate ratio in the HMBi and MHA-Ca groups were significantly higher than those in the Control group (p = 0.006, p = 0.002, p = 0.001, p = 0.004), and the NH3-N concentrations in the HMBi and MHA-Ca groups were significantly lower than those in the Control group (p = 0.004). The 16S rRNA sequencing revealed that the HMBi group had a higher (p = 0.039, p = 0.001, p = 0.027) relative abundance of Bacteroidetes, Firmicutes, and Synergistetes and a lower relative abundance of Proteobacteria (p = 0.001) than the Control group. At the genus level, Prevotella abundance was higher (p = 0.001), while Ruminobacter abundance was lower (p = 0.001), in the HMBi and MHA-Ca groups than in the Control group. Spearman's correlation analysis showed that the relative abundance of Prevotella_1, Streptococcus, and Desulfovibrio was positively correlated with dry matter digestibility, MCP, and fermentation parameters. MHA, thus, significantly increased gas production and altered the rumen fermentation parameters and microbiota composition of sheep.

The influence of coagulant type on the biological treatment of sewage sludge

Anaerobic digestion (AD) and composting are commonly utilized sludge management methods however, the influence of different coagulant types on these biological processes and their stabilized biomass characteristics have not been fully explained. In this study, the effect of the coagulant used in municipal wastewater treatment on the biological stabilization of sludge was investigated. Fully controlled and monitored small-scale AD and composting bioreactors were utilized. The coagulants tested included an inorganic coagulant (IC), polyaluminium chloride (PAC), and organic coagulants, (OC) polyamine (pAmine) and chitosan (Chit). Overall, the coagulant applied showed a measurable influence on the biological stabilization of sludge. The presence of complex organics compounds from OC in the sludge biomass was found to decrease biomass biodegradability while increasing gas production. During AD, Chit-sludge achieved higher biogas production than pAmine- and PAC-sludges (13 % and 16 %, respectively, in Nm3 CH4 t−1VS). In composting, pAmine-sludge achieved the highest feedstock temperature (34–35 °C) and CO2 gas emissions, followed by Chit- (33 °C) and PAC-sludges (32 °C). Generally, tot-P concentration in PAC-sludge was higher than in pAmine and Chit-sludges both before (20, 17 and 15 g/kg DM, consecutively) and after AD (23, 21 and 20.5 g/kg DM, consecutively), and during the composting (31, 29.5 and 26 g/kg DM, consecutively) process. Tot-N concentrations (g/kg DM) showed a substantial increase after AD (pAmine and PAC ca 50 % and Chit 81 %), while a decrease was observed after composting, specifically in PAC-sludge (PAC 28 %, pAmine and Chit ⁓5 %). The selection of the most suitable coagulant by wastewater treatment facilities depends on the objective of the biological stabilization process. In cases where AD is applied and biogas yield is selected as the target output, the semi-natural OC Chit was found to be the best option among the coagulants tested. Comparably, when the nutrient content of resulting biosolids (AD or composting) is more relevant, it was found that OC-produced sludge contained higher N concentrations, while IC-produced sludge contained slightly higher P concentrations.

In vitro evaluation of Aloe saponaria as a potential feed additive to modulate ruminal fermentation and microbial diversity

ABSTRACT Saponin possessed antiprotozoal activity; therefore, it is generally used to mitigate enteric methane (CH4) emission in ruminant nutrition. The objective of this study was to evaluate the effects of Aloe saponaria (AS) supplementation on rumen fermentation, CH4, and microbial diversity in an in vitro experiment over 48 h incubation. Five treatments were used: (1) no additives (CON), 1% and 2% dosage of heat-dried AS (HAS), and freeze-dried AS (FAS), and the experiments were performed three times. After the incubation, volatile fatty acids (VFAs), CH4 proportion in total gas, and microbial diversity were evaluated. Gas production was assessed at 3, 6, 9, 12, 24, 36, and 48 h incubation. FAS addition significantly increased gas production compared to CON except for 6 and 48 h, whereas HAS addition did not significantly affect the gas production at all observed time points. AS addition significantly increased total VFA and the absolute abundances of fungi and Ruminococcus albus regardless of drying method. There was no significant change in the CH4 proportion at 48 h, although the reduction in ciliate protozoa was detected in FAS-treated groups. In conclusion, FAS may be an effective feed additive to improve ruminal fermentation via enhancing feed utilization by rumen microbes.