Liquid Biogas Research Articles

The Sulfur Conversion Functional Microbial Communities in Biogas Liquid Can Participate in Coal Degradation.

The addition of biogas liquid is a practical way to improve the yield of biological coalbed methane. The microbial composition in biogas liquid is complex, and whether it could participate in the sulfur conversion of coal remains unknown. In this study, sulfur conversion-related microbial communities were enriched from biogas liquid, which was dominated by genera Anaerosolibacter, Bacillus, Hydrogenispora, and Oxobacter. The co-culture of these groups with coal significantly changed the coal microbial community composition but did not increase the content of CH4 and H2S. The changed microbial communities mainly belonged to phyla Firmicutes, Proteobacteria, and Actinobacteriota, and increased the relative abundance of genera Bacillus, Thermicanus, Hydrogenispora, Oxobacter, Lutispora, Anaerovorax, Desulfurispora, Ruminiclostridium, and Fonticella. From the microscopic structure of coal, an increase in the number of holes and roughness on the surface of the coal was found but the change of surface functional groups was weak. In addition, the addition of S-related microbial communities increased the contents of phoxim, methylthiobenzoylglycine and glibornuride M5 in aromatic compounds, as well as the content of lauryl hydrogen sulfate in alkyl compounds. Furthermore, the dibenzothiophene degradation-related microbial communities included Bacillus, Brevibacillus, Brevundimonas, Burkholderia-Caballeronia-Paraburkholderia, and Thermicanus, which can break C-S bonds or disrupt benzene rings to degrade dibenzothiophene. In conclusion, the S-related microbial communities in biogas liquid could rebuild the coal microbial community and be involved in the conversion process of organic sulfur in coal.

Biogas liquid digestate application: influence on soil microbial biomass and CO2 respiration

Biogas liquid digestate application: influence on soil microbial biomass and CO2 respiration

Liquid Organic Fertilizer From Biogas Liquid Waste with The Addition of Rabbit Urine, Monosodium Glutamate and Water Hyacinth

Biogas liquid waste has the potential to be used as a base material for liquid organic fertilizer due to the potential for its fairly high organic compund content. Rabbit urine and water hyacinth are known to contain material that are used for plants.MSG ia a cooking spice that contains sodium salt (Na) which is bound to amino acids in the form of glutamate, with Na element being able to improve plants that deficient in potassium (K).The aim of this research is to process liquid biogas waste into liquid organic fertilizer (POC) by adding water hyacinth, rabbit urine, and MSG using an anaerobic process. The results of this research showed that the control POC contained 0.067% N, 0.27% P2O5 and 0.023% K2O. POC A 0.056% N, 0.27% P2O5 and 0.32% K2O. POC B 0.022% N, 0.32% P2O5 and 0.11% K2O.

Growth Dynamics and Nutrient Removal from Biogas Slurry Using Water Hyacinth

Aquatic macrophytes, notably the invasive water hyacinth, exhibit proficiency in nutrient removal from polluted water bodies, rendering them appealing for water remediation applications. This study investigates the potential of water hyacinth in phytoremediation, focusing on the effect of using nutrient-rich biogas slurry mixed with water in varying concentrations, i.e., 16.6, 33, 66.6, 100, and 133 mg/L for the investigation. The physiochemical properties of the liquid biogas slurry were evaluated before and after treatment with water hyacinth over eight weeks, with continuous monitoring of nutrient reduction rates. Results showcased substantial average reductions of nitrogen, phosphorus, and potassium, with a relative growth rate of 5.55%. The treatment also decreased pH, total dissolved solids, hardness, and chemical oxygen demand. The theoretical BMP of water hyacinth was determined using Buswell’s equation. Water hyacinth grown in the concentration of the biogas slurry exhibited the highest methane yield at 199 mL CH4/gm VS, along with the highest relative growth rate. This study used experimental data to create a mathematical model that describes how the relative growth of water hyacinth depends on the number of days and biogas slurry concentration (C). The model’s quality and effectiveness were evaluated using the goodness of fit (R2) and observable approaches. The polynomial model, referred to as Poly model 1, 2, is the best fit for describing the relationship between the growth percentage of water hyacinth, days, and nutrient solution concentration. In this model, C has a polynomial degree of one (normalized mean of 69.84 ± 43.54), while D has a degree of two (normalized mean of 30 ± 21.65).

Comparison of Struvite as a P Source with Chemical Fertilizers and Evaluation of Additional Contribution to Growth and Mineral Nutrition of Lettuce Grown on Acidic and Calcareous Soils

This study investigated the effects of two different struvites (Struvite1 (STR1) and Struvite2 (STR2)) with different P amounts on the P nutrition of lettuce grown in acid and calcareous soils and fertilizer efficiency against di-ammonium phosphate (DAP), monoammonium phosphate (MAP), triple superphosphate (TSP), and 20–20-20 (NPK fertilizer). Two distinct forms of STR1 and STR2 obtained from the biogas liquid digestate (LD, liquid fraction of a centrifuge decanter) at different molar ratios (NH4+/Mg2+/PO43−), STR1 (1.0/1.3/1.0), and STR2 (1.0/1.3/1.3) were used. The results showed that struvites were the most effective treatments for plant growth. STR1 and STR2 treatments increased the plant fresh weights by 2.7-fold in acidic soil and 2.1-fold in alkaline soil. As for the plant dry weights, STR1 and STR2 treatments increased the plant dry weights by 2.4–2.2-fold and 2.3–2.2-fold in acid and alkaline soils, respectively. Struvites were more effective on the total plant weights than other fertilizers. Struvite-applied plants yielded higher P concentrations, uptakes, and recovery than MAP, DAP, TSP, and 20–20-20 fertilizers for both soils. Due to its constituent Mg, STR1 and STR2 were found to be the most effective materials for the Mg nutrition of the plants. It was also determined that they contributed to the N and K nutrition of the plants more than most other fertilizers. In conclusion, it was seen that struvites are not only a good source of P but also a fertilizer material with a high agronomic value. Therefore, they can be evaluated as an alternative fertilizer source.

The Effects of Liquid Biogas Digestate on Yield and Mineral Nutrition of Cucumber Growing in Greenhouse

This study aimed to investigate the effects of a liquid fraction of digestate obtained from different biogas plants on the growth and mineral nutrition of cucumber plants under greenhouse conditions. For this purpose, Liquid Biogas Digestates (LBD) obtained from two different plants (A-B) with different properties were applied to pots with 10 kg of soil in 5 different doses (0, 20, 40, 60, and 80 t ha-1) and the effects of the treatments were observed. As a result of the research, the highest yields increased 24.6% for digestate A in A5 (80 t ha-1) and 29% for digestate B in B3 (40 t ha-1) compared to control. While LBD contributed to the increase of N, Ca, Zn, Cu, and Mn concentrations in the leaf samples, it was observed that the dose increase did not have a linear effect on N, Ca, Zn, Cu, and Mn concentrations in the leaf samples. It is thought that liquid biogas wastes produced in biogas plants have positive effects on fruit yield, agricultural practices can be taken as the basis for the disposal of these wastes and the use of liquid biogas residues in soils by eliminating potential risks can provide significant benefits.

Optimization of Biogas Liquid Waste from Livestock Manure as a Source of Renewable Energy through Microbial Fuel Cell (MFC) Technology

This study examines the potential of biogas liquid waste as a source of electrical energy through microbial fuel cell (MFC) technology. The results showed that biogas effluent in one-room MFC produced a maximum voltage of 1302.2 mV. In the two-room MFC with KMnO4 electrolyte, the voltage reached 1084.3 mV with an electric current of 0.1 mA. At the same time, the two-chamber MFC with K2Cr2O4 advanced a maximum voltage of 1675.8 mV and an electric current of 0.99 mA. Characterization of the MFC substrate showed a decrease in organic matter of biogas liquid waste, with C-organic content of 2.20%, total nitrogen of 1.85%, and C/N ratio of 1.19. The COD value decreased to 500.96 mg/L, while the BOD level decreased to 300.23 mg/L. Bacteria in MFC from biogas effluent are dominantly Gram-positive with rod and Sarcina forms, except for one Gram-negative isolate in the form of Spirillum.

Valorization of liquid waste generated from biogas production as supplemental material in shiitake mushroom cultivation

The aim of the study is to investigate the effect of supplementation of growing media with different levels of biogas liquid waste (BLW) on the production of two commercial strains of shiitake (LE-Agroma and LE-Homegreen). The strains were cultivated on oak sawdust (OS) soaked with water containing 0, 2.5, 5, and 10% percentages of BLW and the effect of different treatments was evaluated for cultivation cycle, yield, biological efficiency, nutritional content, macro- micro element contents and accumulation of heavy metals in the fruiting body. The shortest cultivation cycle for shiitake mushrooms, i.e., 82.3 and 75.6 days, was obtained with 10% BLW treatment in LE-Agroma and LE-Homegreen, respectively. The strains displayed the highest yield and BE (297.82 g kg−1–87.6% and 225.89 g kg−1–75.8%, respectively) in the same treatments. The use of BLW positively affected the fat, carbohydrate, macro and micro element contents of shiitake strains, whereas its increased supplementation inversely affected the protein content of the fruiting body. Accordingly, the left-over BLW after biogas production can be successfully used as an additive to cultivate shiitake mushrooms, with no risk to human health.

Mitigating nitrate leaching in cropland by enhancing microbial nitrate transformation through the addition of liquid biogas slurry

Nitrate leaching in croplands with excessive chemical fertilizer application is a serious issue for sustainable agriculture. Microbes are the primary drivers of nitrate transformation in the soil and are considered a potential solution for nitrogen leaching. However, practical approaches are lacking. In this study, the effects of the addition of biogas slurry on nitrogen leaching and soil microbial communities were investigated. Column incubation experiments showed that the addition of biogas slurry at a depth of 20 cm significantly decreased nitrate leaching by 30.97% and shaped a bacterial community rich in taxa involved in nitrate ammonification and denitrification. Using a mechanized application method, the field experiment showed that biogas slurry application significantly increased the abundance of nirK-, nirS-, nosZ-, and nrfA-harboring microbes and decreased the risk of nitrate leaching without reducing crop yield and the soil nitrogen pool. These results showed that the appropriate application of biogas slurry effectively mitigates nitrogen leaching by enhancing soil microbial nitrate transformation and confirmed the feasibility of solving environmental problems by regulating the microbial community and function.

Investigation of distribution uniformity of distributor for biogas slurry application based on CFD analysis

A horizontal distributor for biogas slurry application was proposed to explore the distribution performance through CFD analysis and verified by field test. The rheological properties of biogas slurry were analyzed at first, and key parameters were obtained for the next simulation. The effects of distribution modes, inlet direction, and outlets number on the velocity distribution of flow field and mass flow rate of the horizonal distributor were investigated by CFD simulations. Results of rheological properties indicated that biogas slurry was a non-Newtonian fluid and exhibited shear-thinning behavior. It can be well described by power-law model. The simulation results showed that the geometry of rotor, especially the block numbers was the main factor that determining the fluid movement and trajectory of distribution and output. The mode rotor 1 with two blocks reached the lowest variable coefficient of mass flow rate (4.49%), indicating a higher degree of uniformity. The upward inlet direction would obtain less dead zone, and the distributor with an even outlets number would possess more uniform distribution and less dead zone. The field test of the distributor with rotor 1, upward inlet direction, and 24 outlets has been carried on to verify the simulation results, the variable coefficient of mass flow was 13.06%, which was slightly higher than the simulation (9.23%), but it still within the range of requirement (<15%). The proposed model and the findings of this work are of guiding significance for the study of the utilization technology and equipment of liquid biogas residue. Keywords: distributor, biogas slurry, distribution uniformity, rheological properties, CFD DOI: 10.25165/j.ijabe.20231601.7460 Citation: Fu J J, Chen Y S, Xu B X, Ma B, Wang P J, W A B, et al. Investigation of distribution uniformity of distributor for biogas slurry application based on CFD analysis. Int J Agric & Biol Eng, 2023; 16(1): 45–52.

Effects of Two Kinds of Commercial Organic Fertilizers on Growth and Rhizosphere Soil Properties of Corn on New Reclamation Land.

Due to the development of urbanization and industrialization, a large amount of cultivated land resources has been occupied, while new reclamation land could expand the supply of usable land for food security. Organic fertilizers, such as crop residues, biosolids, sheep manure, mushroom residue, and biogas liquid, have been considered as an effective amendment in immature soil to improve its quality. Recently, two kinds of commercial organic fertilizers, pig manure and mushroom residue organic fertilizer (PMMR-OF), and sheep manure organic fertilizer (SM-OF), have been more regularly applied in agriculture production. However, the information available on effect of the two kinds of fertilizers on plant growth and rhizosphere soil properties in immature field is very limited. In order to evaluate PMMR-OF and SM-OF on immature soil, the soil quality and microbial community structure of corn rhizosphere soil samples under the two kinds of organic fertilizers at different concentrations was investigated. The results revealed a significant difference between commercial organic fertilizers (especially SM-OF) and chemical compound fertilizers (CCF) in soil properties and microbial community structure. Indeed, compared with the control based on16S and ITS amplicon sequencing of soil microflora, SM-OF caused a 10.79–19.52%, 4.33–4.39%,and 14.58–29.29% increase in Proteobacteria, Actinobacteria, and Ascomycota, but a 5.82–20.58%, 0.53–24.06%, 10.87–16.79%, 2.69–10.50%, 44.90–59.24%, 8.88–10.98%, and 2.31–21.98% reduction in Acidobacteria, Gemmatimonadetes, Bacteroidetes, Verrucomicrobia, Basidiomycota, Mortierellomycota, and Chytridiomycota, respectively. CCF caused a 24.11%, 23.28%, 38.87%, 19.88%, 18.28%, and 13.89% reduction in Acidobacteria, Gemmatimonadetes, Bacteroidetes, Verrucomicrobia, Basidiomycota, Chytridiomycota, but a 22.77%, 41.28%, 7.88%, and 19.39% increase in Proteobacteria, Actinobacteria, Ascomycota, and Mortierellomycota, respectively. Furthermore, redundancy discriminant analysis of microbial communities and soil properties of PMMR-OF, SM-OF, CCF, and the control treatments indicated that the main variables of bacterial and fungal communities included organic matter content, available P, and available K. Overall, the results of this study revealed significant changes under different fertilizer conditions (PMMR-OF, SM-OF, CCF, under different concentrations) in microbiota and chemical properties of corn soil. Commercial organic fertilizers, particularly SM-OF, can be used as a good amendment for the new reclamation land.

Biogas Production and Applications in the Sustainable Energy Transition

Biogas is competitive, viable, and generally a sustainable energy resource due to abundant supply of cheap feedstocks and availability of a wide range of biogas applications in heating, power generation, fuel, and raw materials for further processing and production of sustainable chemicals including hydrogen, and carbon dioxide and biofuels. The capacity of biogas based power has been growing rapidly for the past decade with global biogas based electricity generation capacity increasing from 65 GW in 2010 to 120 GW in 2019 representing a 90% growth. This study presents the pathways for use of biogas in the energy transition by application in power generation and production of fuels. Diesel engines, petrol or gasoline engines, turbines, microturbines, and Stirling engines offer feasible options for biogas to electricity production as prme movers. Biogas fuel can be used in both spark ignition (petrol) and compression ignition engines (diesel) with varying degrees of modifications on conventional internal combustion engines. In internal combustion engines, the dual-fuel mode can be used with little or no modification compared to full engine conversion to gas engines which may require major modifications. Biogas can also be used in fuel cells for direct conversion to electricity and raw material for hydrogen and transport fuel production which is a significant pathway to sustainable energy development. Enriched biogas or biomethane can be containerized or injected to gas supply mains for use as renewable natural gas. Biogas can be used directly for cooking and lighting as well as for power generation and for production of Fischer-Tropsch (FT) fuels. Upgraded biogas/biomethane which can also be used to process methanol fuel. Compressed biogas (CBG) and liquid biogas (LBG) can be reversibly made from biomethane for various direct and indirect applications as fuels for transport and power generation. Biogas can be used in processes like combined heat and power generation from biogas (CHP), trigeneration, and compression to Bio-CNG and bio-LPG for cleaned biogas/biomethane. Fuels are manufactured from biogas by cleaning, and purification before reforming to syngas, and partial oxidation to produce methanol which can be used to make gasoline. Syngas is used in production of alcohols, jet fuels, diesel, and gasoline through the Fischer-Tropsch process.

Techno-Economic Assessment of Solid–Liquid Biogas Treatment Plants for the Agro-Industrial Sector

The urgent need to meet climate goals provides unique opportunities to promote small-scale farm anaerobic digesters that valorize on-site wastes for producing renewable electricity and heat, thereby cushioning agribusinesses against energy perturbations. This study explored the economic viability of mono-digestion of cow manure (CWM) and piglet manure (PM) in small manured-based 99 kWel plants using three treatment schemes (TS): (1) typical agricultural biogas plant, (2) a single-stage expanded granular sludge bed (EGSB) reactor, and (3) a multistage EGSB with a continuous stirred tank reactor. The economic evaluation attempted to take advantage of the financial incentives provided by The Renewable Energy Sources Act in Germany. To evaluate these systems, batch tests on raw and solid substrate fractions were conducted. For the liquid fraction, data of continuous tests obtained in a laboratory was employed. The economical evaluation was based on the dynamic indicators of net present value and internal return rate (IRR). Sensitivity analyses of the electricity and heat selling prices and hydraulic retention time were also performed. Furthermore, an incremental analysis of IRR was conducted to determine the most profitable alternative. The most influential variable was electricity selling price, and the most profitable alternatives were TS1 (CWM) &gt; TS1 (PM) &gt; TS3 (CWM). However, further studies on co-digestion using TS3 are recommended because this scheme potentially provides the greatest technical flexibility and highest environmental sustainability.

Efektivitas Pemberian Limbah Biogas Sapi Terhadap Kadar Protein Jerami Jagung Untuk Pakan Ternak

Plant-livestock integration was one of the concepts of integrated agriculture. Agricultural waste had the potential to be developed as animal feed material, such as corn straw. The availability of waste, such as agricultural, livestock and biogas wil pollute the environment if it is not utilized. Therefore, the purpose of this study was to determine the effect of giving biogas waste on the protein content of corn straw, as a by-product of corn cultivation. The treatment in this study used two factors, namely (i) cow biogas solid waste consisting of 2 treatment levels, namely 0 and 5.4 tons/ha, and (ii) cow biogas liquid waste consisting of 4 treatment levels, namely 0 liter/ha. , 500 liters/ha, 1000 liters/ha and 1500 liters/ha. The data measured were nitrogen content, nitrogen absorption and protein content of corn straw. The results showed that the application of biogas waste was able to increase the protein content of corn straw.

Co-digestion of water hyacinth, municipal solid waste and cow dung: A methane optimised biogas–liquid petroleum gas hybrid system

Fossil fuels are still the major source of energy in developing countries, howbeit expensive and environmentally unsustainable. Co-digestion substrate proportions and the respective biogas potentials for a huge number of biomaterials for anaerobic digestion are yet to be ascertained let alone optimised. This paper presents a novel methane-optimised biogas–liquid petroleum gas hybrid system concept. Herein this research, biogas is produced from the anaerobic co-digestion of water hyacinth, municipal solid waste and cow dung. A model that incorporated seasonal variations of biomass feedstocks was developed; an optimisation problem was formulated and solved using the Optimisation Interface tool (OptiTool) in combination with the Solving Constraint Integer Programs (SCIP) toolbox in Matrix Laboratory (MATLAB). The biogas production reactions are optimised in such a way that the methane component of the biogas is maximised, and the other components minimised by the integration of a model which necessitates the feed in of optimal substrate masses as per the ratios ascertained for the substrates considered thereby yielding a high quality combustible biogas product. The methane-optimised biogas is channelled towards some community gas demand and liquid petroleum gas comes in to fill the discrepancy between the methane-optimised biogas and the gas demand. Consideration of seasonality changes in the availability of substrates in the modelling and optimisation led to an increase of 174.58% in annual biogas output. A 6.97% annual lowest cost savings was realised in winter and 18.24% annual highest cost savings was realised in summer from the methane-optimised biogas–liquid petroleum gas hybrid system.

Organic Waste-Based Fertilizer in Hydroponics Increases Tomato Fruit Size but Reduces Fruit Quality.

In regions with intensive agricultural production, large amounts of organic waste are produced by livestock animals. Liquid digestate from manure-based biogas production could potentially serve as fertilizer if integrated with closed horticultural irrigation systems. The aim of this experiment was to investigate how fertilizer based on liquid biogas by-products of pig manure digestion can affect the growth and production of tomato plants. Integration of a nitrification bioreactor presumes a significantly lower concentration of nutrient solutions and a higher level of oxygenation than classical mineral cultivation. Therefore, additional controls were included. We compared plant growth and fruit quality traits of tomato plants grown in a hydroponic solution with organic fertilizer with two levels of mineral fertilizer. The tomatoes grown with organic waste-based liquid fertilizer showed reduced growth rates but increased mean fruit size, resulting in no significant change in total yield compared with high-mineral cultivation. The growth rate was similarly reduced in plants cultivated with low-mineral fertilizer. Plants cultivated with organic waste-based fertilizer had high Cl− concentration in xylem sap, leaves, and, ultimately, fruits. The leaves of plants cultivated with organic waste-based fertilizer contained higher concentrations of starch and soluble carbohydrate and low concentrations of phosphorous (P) and sulfur (S). The plants grown with organic waste-based or low-mineral medium showed significantly poorer fruit quality than the plants cultivated with the high-mineral solution. The low-mineral treatment increased xylem sap contribution to fruit weight because of higher root power. The organic waste-based fertilization did not change the root power but increased fruit size. In conclusion, organic waste-based cultivation is a possible solution for sustainable plant production in greenhouses. However, additional adjustment of nutrient supply is required to improve fruit quality.

The Innovation of Tofu Waste Liquid Biogas Reactor Technology as an Alternative Energy Resource

Abstract - Increased production capacity of the tofu factory has an impact on increasing waste. Tofu liquid waste is one of the untapped wastes and even just thrown away. Besides, the tofu industry needs water for its processing, so more wastewater produces more than tofu solid waste. Wastewater from the making tofu process produces liquid waste which is a source of pollution for humans and the environment that will disrupt the ecosystem and environmental health. The right process for handling tofu wastewater is by an anaerobic process that converts the liquid waste fermented by bacteria into methane gas. This methane gas can be used as a new energy resource and this energy can be used for cooking or frying tofu. The results of the research are from 500 liters of tofu liquid waste treated, 149.6 liters of biogas were obtained in 21 days. It increased the quality of biogas as seen from the increase in CH 4 levels by 70%, temperature in the digester by 32 o C, volume in 149.6 liters, and decreasing H 2 S levels by 9 ppm, CO by 13 ppm, O 2 by 15.1%. Based on the test results, the maximum fermentation time is 21 days.

Use of polyacrylamide modified biochar coupled with organic and chemical fertilizers for reducing phosphorus loss under different cropping systems

Agricultural cropping systems involve the application of high fertilizer rates, which lead to phosphorus (P) losses via surface runoff to the aquatic environment, thereby resulting in severe eutrophication. Here, to evaluate the nutrient loss, we established three monitoring stations in Zhejiang Province, China, in each of which the crop types were double cropping rice, rice–wheat rotation, and vegetable cultivation. Field experiments were conducted with four treatments and three replications over a whole planting year. The four treatments at the same P application rate were: 1) no fertilization (control; CK), 2) chemical fertilization (CF), 3) substitution of 30 % chemical P in CF by organic P in solid sheep manure (OF) or in liquid biogas slurry (BS), and 4) substitution of 30 % chemical P in CF by organic P fertilizers (solid sheep manure or liquid biogas slurry) +1.5 t ha−1 polyacrylamide modified BC (PSB). The runoff losses of various P forms, that is, the total P, total dissolved P, particulate P, and colloidal P losses were analyzed. The total P concentration varied greatly with the crop growth stages. Compared with CF treatment, PSB treatment significantly reduced the concentration of P fractions in the runoff in all three cropping systems, while the OF treatment significantly reduced the particulate P and colloidal P concentrations by coating colloidal particles with organic carbon. However, BS treatment increased particulate P and colloidal P concentrations. Compared with CF treatment, PSB treatment reduced total P loss by 41.1 %, 29.7 %, and 37.8 % in the double cropping rice, rice–wheat, and vegetable systems, respectively. The PSB and OF treatments significantly reduced the particulate P and colloidal P losses, while BS treatment increased the loss of various P forms. Compared with the CF treatment, the PSB treatment significantly increased the available P contents by 12.7–85.4 mg kg-1, and decreased the colloidal P contents by 26.7 %–51.4 % in the soils examined. The results of the redundancy analysis confirmed that P loss via runoff was mainly caused by differences in the P inputs and crop types. The results of this study highlight the important role of PSB in reducing P loss via runoff from agricultural cropping systems.

Study of Occurrence Characteristics of Antibiotic Resistance Genes in Pig manure during Anaerobic Digestion and Digestate Fertilization

Antibiotic resistance genes (ARGs) existing in livestock and poultry manure have the risk to spread and proliferate. This might endanger people’s health. The common treatment of livestock and poultry manure is anaerobic digestion. But the change of ARGs during anaerobic digestion require further study, and the effect of digestate fertilization to the antibiotic resistance of cropland soil is still unclear. This study investigated the pig manure, biogas liquid, biogas residue, and cropland soils fertilized with and without digestate. The results showed that, the relative abundance of ARGs in biogas residue was much higher than other samples. The average relative abundance was 1.46×10-1 copy ratio (copy of ARG/copy of 16S rRNA gene), and the total relative abundance was 3.07 copy ratio. There were 21 ARGs detected in the 5 samples. 11 of them were shared by the 5 samples. The main ARGs were aminoglycoside, chloramphenicol, sulfonamide, tetracycline, and multidrug. Aminoglycoside had the highest relative abundance, and the total relative abundance in all samples was 1.18 copy ratio. Anaerobic digestion increased the total relative abundance of ARGs in pig manure from 1.14×10-1 to 1.70×10-1 copy ratio. Fertilization of digestate increased the total relative abundance of AGRs in soil from 3.27×10-1 to 7.29×10-1 copy ratio.

Utilization of Biogas Liquid Waste For Starter In The Fermentation of Rice Husk As A Potential Feed For Poultry

The research was aimed to evaluate the effect of biogas liquid waste as a fermentation starter of rice husk to the nutrient content, gross energy and bulk density. The method used laboratory experiment using a completely randomized design (CRD) on factorial pattern (6 x 5) with the level of biogas waste liquid : P0-treatment (0% negative control), P0+ (Cellulomonas sp as positive control), P1 (5%), P2 (10%), P3 (15%), P4 (20%) ml/g, and the incubation time : T0 (0 day control ), T1(7 days), T2 (14 days), T3 (21 days) and T4 (28 days). The variables measured was the content of ash, crude protein, crude fiber, crude fat, gross energy and bulk density. Data were analyzed by analysis of variance (anova) CRD Factorial pattern and if there is a significant difference was followed by Duncan's Multiple Range Test. The results of research was the level of biogas liquid waste and the incubation time provides a significant influence (P&lt;0.01) on the nutrient content, gross energy and bulk density of rice husk. The interaction level liquid waste provision of biogas and incubation time was highly significant (P&lt;0.01) on the nutrient content, gross energy and bulk density. It can be concluded that the addition of biogas liquid waste 15% (ml/g) with a time of incubation for 21 days have best rice husk quality content based on improvement of crude protein, crude fat, and gross energy with lowest crude fiber.