A Biogas Production Model from the Combination of Pig Manure and Cow Dung in N’Zérékoré City, Republic of Guine

This present research work focuses on the valorization of pig droppings for production of biogas in mono digestion and co-digestion with proportions of cow dung from the urban commune of N’Zérékoré. It was carried out in December 2020 in the Physics laboratory of the University of N’Zérékoré. The anaerobic digestion process took 25 days in an almost constant ambient temperature of 25˚C. Five digesters were loaded on 12/06/2020, two of which with 1 kg of pig dung and 1 kg of cow dung both in mono-digestion. The 3 other digesters in co-digestion with different proportions of pig manure and cow dung. The substrate in each digester is diluted in 2 liters of water, with a proportion of (1/2). The main results obtained are: 1) the evolution of the temperature and pH during digestion process, 2) the average biogas productions 0.61 liters for (D1);1.20 liter for (D2);1.65 liter for (D3);1.51 liter for (D4) and 1.31 liter for (D5). The cumulative amounts of biogas are respectively: D1 (7.95 liters), D2 (15.60 liters), D3 (21.50 liters), D4 (19.65 liters) and D5 (17.05 liters). The total cumulative production is 81.75 liters at the end of the process. The originality of this research work is that the proposed model examines the relation between the daily biogas production and the variation of temperature, pH and pressure. The combustibility test showed the biogas produced during the first week was no combustible (contains less than 50% methane). Combustion started from the biogas produced from the 15th day and it is from the 20th day that a significant amount of stable yellow/blue flame was observed. The results of this study show the combination of pig manure and cow dung presents advantages for optimal biogas production.

Isolation,Screening and Identification of High-temperature Cellulolytic Microbes in Pig Manure

[Objective] The research aimed to lay the foundation for high-efficiency biological degradation microbial inoculums. [Method] under the 60℃ temperature the cellulolytic microbes in pig manure were isolated and determined the CMCase and Fpase,then proceeded the 16S rRNA gene analysis. [Result]The results showed that:BC1 and BC3 strains characterized higher carboxymethyl cellulose enzyme activity and higher filter paper activity,but their difference was small,then the 16S rDNA sequence of BC1 and BC3 strains were related to pseudomonas sp. (98% and 99% similarities,respectively).[Conclusion] the experiment laid foundation for high-efficiency biological heating agent.

Effect of Pig Manure Application on Structural Characteristics of Humic Acids in Brown Soil

The effect of application of pig manure (PM) on the structural characteristics of humic acids (HAs) of brown soil was studied in field and incubation experiments. The results showed that the number-average molecular weights (Mn), the ratios of C/ H, C/ N and O/C, the contents of carboxyl and phenolic hydroxyl groups, the content ofaromatic C, the values of E2, E4and λ Exmax of HAs all decreased; whereas, the contents of alkyl C and O-alkyl C, the ratio of carboxyl to phenolic hydroxyl groups, the degree of oxidation stability, the absorption intensity at 285 mμ (UV), and 2920cm-1 of HAs increased after the application of PM. The above results indicated that the molecular structure of HAs tended to be more aliphatic and simpler after the application of PM.

Changes in speciation,mobility and bioavailability of Cd,Cr and As during the transformation process of pig manure by black soldier fly larvae(Hermetia illucens)

The black soldier fly larvae(BSFL)(Hermetia illucens)are a good candidate for poultry and livestock manure treatment.The harvested insect bodies and feces can be used as animal feed and organic fertilizer.However,heavy metals have a negative impact on the transformation process of the manure by BSFL.Here we evaluated the effects of Cd,Cr and As in pig manure on the growth of BSFL,as well as the mobility and changes in speciation of the metals during the transformation process.The results showed that As significantly reduced the weight of BSFL,but Cr and Cd had no significant effects on BSFL growth.The bioaccumulation factors(BAFs)at various concentrations of Cd(2.8–3.7)were significantly higher than those of Cr(0.44–0.62)and As(0.43–0.45).The heavy metals in pig manure were mainly transferred to BSFL feces,and the distribution percentages of Cd,Cr and As in the BSFL feces were 52.6–62.0%,90.3–94.2%and 93.0–93.3%,respectively.Cd concentrations in BSFL feces were significantly lower than those in the pig manure,while there were no significant differences in the concentrations of Cr and As between BSFL feces and pig manure(except for the treatment with the addition of 150 mg Cr kg^(–1)).The metal speciation(weak acid soluble,reducible,oxidizable and residual fractions)in BSFL feces obviously changed when compared with pig manure.In BSFL feces,the reducible proportion of Cr decreased while the oxidizable proportion increased.Cd mainly existed in the weak acid soluble and reducible states in pig manure and BSFL feces.For As,the proportions of weak acid soluble and reducible states decreased in BSFL feces.After the BSFL transformation process,the bioavailable fraction of Cr decreased by 17.3–23.1%,but those of Cd and As did not change significantly,except for As in the CK group.These findings contribute to our understanding of the roles of BSFL during the biotransformation process of livestock manure as well as the safe utilization of transformed products.

Nitrogen transformations during pig manure composting

Composting is now suggested as one of the environmentally and friendly alternative method for disposal of solid organic wastes, as it leads to minimization, stabilization, and utilization of organic waste. Transformations of nitrogen were investigated in co-composting of pig manure with different amendments, such as sawdust and leaves. Samples were analyzed for pH, total-N, soluble NH4-N, soluble NO3-N and soluble organic-N. The total-N increased after 63 days of composting, as well as the soluble NO3-N and soluble organic-N. Soluble NH4,-N increased significantly and showed peak values at day 7, thereafter decreased sharply and gradually to lower levels. Seed germination index (GI) showed that co-composting of pig manure with sawdust reached maturity after 49 days of composting, while co-composting of pig manure with sawdust and leases required shorter time for 35 days. Soluble NH4-N was significantly negatively ( P < 0.05) , while soluble NO3-N and soluble organic-N were significantly positively ( P < 0.05), correlated with seed germination index (GI). Addition of leaves in co-composting of pig manure with sawdust had no significant impacts on nitrogen transformations, but it was beneficial for maturity of pig manure compost.

Pig Manure Systems in Germany and China and the Impact on Nutrient Flow

Germany and China use different stable systems for fattening pigs. Widespread systems in Germany are closed stables with slatted or partly slatted floor, which produce liquid manure （a mixture of urine, faeces, and cleaning water） whereas in China open stables with closed concrete floors are used with separate collection of faeces and urine. Based on data from literature and own analyses nutrient flows of both systems are calculated. The Chinese manure system or mechanized belt or V-shaped pit floor systems with faeces/urine separation are more effective to separate solids, nutrients, carbon, and heavy metal than mechanical separation from liquid manure. The separation rates can be up to 88% for the solids, 67% for nitrogen, 93% for phosphorus, 60% for potassium, 94% for magnesium, 97% for cupper, and 98% for zinc. The faeces can be used for composting to produce a market product.

Changes in Phosphorus Fractions and Nitrogen Forms During Composting of Pig Manure with Rice Straw

The study was conducted to reveal P fractions and N forms changing characters during composting of pig manure with rice straw.During composting,the NH 4 ＋-N concentration decreased and reached at a relatively low value（〈400 mg kg-1） in the final compost,while the NO 3--N concentration increased.Total N losses mainly occurred during thermophilic phase due to the high temperature,the high NH 4 ＋-N concentration and the increase of pH value.Labile inorganic P was dominated in the pig manure and initial compost mixture.During composting,the proportion of labile inorganic P of total extracted P decreased,while the proportion of Fe＋Al-bound P,Ca＋Mg-bound P and residual P increased.The evolutions of the proportion of labile inorganic P,Fe＋Al-bound P and Ca＋Mg-bound P were well correlated with the changes of pH value,organic matter and C/N ratio.Therefore,composting could increase the concentration of N and P and decrease the presence of NH 4 ＋-N and labile P fractions which might cause environmental issues following land application.

Treatment Effect of Pig Manure-derived Biochar-based Metal Catalyst for Pig Breeding Wastewater

[Objectives]To treat pig farm wastewater and solve the problem of pollution caused by it to surface water or groundwater.[Methods]Fe and Zn/biochar(AC)was prepared by dipping method using pig manure-derived biochar as carrier.The preparation conditions were investigated,and the screened metal-loaded biochar was characterized.Pig farm waste water was treated with metal-loaded biochar-H2O2 catalytic oxidation method.[Results]At the COD concentration of 2904 mg/L,0.02 g Zn/AC and 0.005 mL H2O2 showed the highest COD removal rate(qe)from pig breeding wastewater under conditions of reaction time of 8 h,pH value of 7 and temperature of 55℃,reaching 70.98%.[Conclusions]Fe or Zn-loaded biochar made from pig manure-derived activated carbon has a certain catalytic capacity for the actual oxidation treatment of pig farm wastewater.The activity of Zn/AC was higher,and its COD removal rate from pig farm wastewater was also higher.

Investigates of substrate mingling ratio and organic loading rate of KOH pretreated corn stover and pig manure in batch and semi-continuous system:Anaerobic digestion performance and microbial characteristics

The effects of substrate mingling ratio(SMR)(1:1,1:2,1:3,3:1,and 2:1)and organic loading rate(OLR)(50-90 g total solids per liter per day)on anaerobic co-digestion performance and microbial characteristics were investigated for pig manure(PM)and pretreated/untreated corn stover in batch and semicontinuous anaerobic digestion(AD)system.The results showed that SMR and pretreatment affected co-digestion performance.The maximum cumulative methane yield of 428.5 ml·g^(-1)(based on volatile solids(VS))was obtained for PCP13,which was 35.7%and 40.0%higher than that of CSU and PM.In the first 5 days,the maximum methane yield improvement rate was 378.1%for PCP13.The daily methane yield per gram VS of PCP13 was 11.4%-18.5%higher than that of PC_(U)13.Clostridium_sensu_stricto_1,DMER64,and Bacteroides and Methanosaeta,Methanobacterium,and Methanospirillum had higher relative abundance at the genus level.Therefore,SMR and OLR are important factor affecting the AD process,and OLR can affect methane production through volatile fatty acids.

Chemical and Biological Evaluation of Maturity of Pig Manure Compost at Different C/N Ratios

Aerobic static pile composting (mechanical turning every 3 days) of pig manure was prepared at & m3 windrow heaps. Sawdust was used as the bulking agent to provide additional carbon and to increase the porosity of the substrate. Two treatments at initial C/N ratios of 30 and 15, respectively, were designed in the study. Dissolved organic carbon (DOC), soluble NH+4-N, C/N ratios in solid and aqueous phases, E4/E6 ratios, and seed germination index (GI) were determined to evaluate the maturity of the co-composts. Seed germination index, a biological parameter, was suggested as one of the most reliable maturity indicators for organic compost. The results showed that the treatment at the initial C/N ratio of 30 reached maturity after 49 days of composting; however, the treatment at the initial C/N ratio of 15 should require composting time of longer than 63 days to obtain maturation. Chemical multi-indicator evaluation was necessary, and the GI measurement was the recommended approach for maturity evaluation in the study.

Effects of Synergy between Earthworms and Effective Microorganisms on Vermicomposting of Pig Manure

[ Objective] To explore the effects of synergy between earthworms （ Eisenia foetida） and effective microorganisms （EM） on vermicom. posting of pig manure and to provide a new idea for rational and effective utilization and treatment of animal manure. [Method] Four treatments were used to compost pig manure, namely, EM-inoculated manure, earthworms-inoculated manure, EM and earthworms-inoculated manure and control （CK） manure. The experiment lasted for 60 d. On Day 0, 15, 30, 45 and 60, the pig manure was collected, and the content of total organic carbon （TOC）, total Kjeldahl nitrogen （TKN）, ammonium nitrogen, nitrate nitrogen and water soluble carbon （WSC） was determined, respectively. [Resuit] Compared with the control, the EM and earthworms-inoculated manure had a decrease of 42.8% in the TOC content, an increase of 13.6% in the TKN content, a decrease of 49.5% in the carbon nitrogen ratio, the conversion rate of ammonium nitrogen of 98.1%, a 96 times increase in nitrate nitrogen, the ratio of nitrate nitrogen to ammonium nitrogen of 61, and a decrease of 58.9% in the WSC content. [ Conclusion] The synergy between earthworms and EM can accelerate maturation of pig manure and improve mineralization and stability of products.

Application of Highly Efficient Microbial Agent in Pig Manure Compost

[ Objective] The aim of this study was to develop a cheap and localized microbial agent so as to solve high cost of microbial agent for pig manure composting in Jiaxing City. [ Method] Pig manure in the experimental group and control group was inoculated with the self-developed micro- bial agent and commercial microbial agent, respectively. The manure was decomposed for 38 d, during which the indicators of compost including physical properties, temperature, pH value, water content, organic matter, dissolved nitrogen, carbon nitrogen ratio and germination rate were studied. [ Result] The water content in the experimental group declined to 26.10% after 33 d of compost, meeting the standard upper limitation of 30% for maturity. By comparison, the water content in the control group was slightly higher than 30% even after 38 d. The germination rate of seeds fertilized with the experimental manure compost met the standard for maturity on Day 28, while that in the control group met the standard for maturity on Day 35. When the composting was finished, the ratio of total carbon to total nitrogen in the pig manure was 14.64 and 16.43 respective- ly in the experimental and control group, and the organic matter content was about 45% for both. All these indexes could meet the standards for or- ganic fertilizer products. [ Conclusion] The self-developed microbial agent can moot the requirements for pig manure composting, and it can shorten the composting time by 5 -8 d compared with the commercial agent. In addition, the fertilizer product composted by the self-developed microbial a qent has lower water content and thereby is much more beneficial for preservation.

Effect of exogenous additives on heavy metal passivation and nitrogen retention in pig manure composting

The widespread use of feed additives in intensive and large-scale pig farming has resulted in high levels of heavy metals in pig manure.The long-term application of organic fertilizers containing high levels of heavy metals leads to the accumulation of heavy metals in the soil,which not only causes heavy metal pollution in the soil,and also affect food safety and endanger human health.Composting is an economical and effective technical measures to achieve environmentally-sustainable treatment of pig manure and is a practical method to reduce the problem of heavy metals and to improve the resource value of pig manure.The composting process is accompanied by high temperatures and the production and emission of gases,and also lead to changes in the nitrogen content of the compost and provide opportunity for heavy metal passivation additives.This paper summarizes the forms and types of heavy metals present in pig manure and reviews the progress of research as well as the techniques and problems of in the composting process,and provides recommendations for research on heavy metal passivation and nitrogen retention in pig manure composting.

Influence of bulking agents on CH_4,N_2O,and NH_3 emissions during rapid composting of pig manure from the Chinese Ganqinfen system

Mismanagement of the composting process can result in emissions of CH4,N2O,and NH3,which have caused severe environmental problems.This study was aimed at determining whether CH4,N2O,and NH3 emissions from composting are affected by bulking agents during rapid composting of pig manure from the Chinese Ganqinfen system.Three bulking agents,corn stalks,spent mushroom compost,and sawdust,were used in composting with pig manure in 60 L reactors with forced aeration for more than a month.Gas emissions were measured continuously,and detailed gas emission patterns were obtained.Concentrations of NH3 and N2O from the composting pig manure mixed with corn stalks or sawdust were higher than those from the spent mushroom compost treatment,especially the sawdust treatment,which had the highest total nitrogen loss among the three runs.Most of the nitrogen was lost in the form of NH3,which accounts for 11.16% to 35.69% of the initial nitrogen.One-way analysis of variance for NH3emission showed no significant differences between the corn stalk and sawdust treatments,but a significant difference was noted between the spent mushroom compost and sawdust treatments.The introduction of sawdust reduced CH4emission more than the corn stalks and spent mushroom compost.However,there were no significant differences among the three runs for total carbon loss.All treatments were matured after 30 d.

Microbial population dynamics and changes in main nutrients during the acidification process of pig manures

This study evaluated the impact of pig manure acidification on anaerobic treatment and composition of the fecal microbial community. According to the different chemical oxygen demand （COD） in the anaerobic treatment processes, pig manure was diluted 4 times （×4）, 16 times （×16）, or 64 times （×64） and subjected to acidification. During the acidification process, pH, soluble chemical oxygen demand （SCOD）, volatile fatty acids （VFAs）, nitrogen （N）, phosphorus （P） and potassium （K） were determined along with microbial population dynamics. The pH of the three dilutions first declined, and then slowly increased. The total VFAs of x4 and xl6 dilutions peaked on day 15 and 20, respectively. The content of acetic acid, propanoic acid, butanoic acid and valeric acid of the × 4 dilution were 23.6, 11.4, 8.8 and 0.6 g/L respectively, and that of the xl6 dilution was 5.6, 2.3, 0.9 and 0.2 g/L respectively. Only acetic acid was detected in the ×64 dilution, and its level peaked on day 10. The results showed that the liquid pig manure was more suitable to enter the anaerobic methanogenic hioreactors after two weeks of acidification. During the acidification process, total P concentration increased during the first ten days, then dropped sharply, and rose again to a relatively high final concentration, while total N concentration rose initially and then declined. Based on the analysis of denaturing gradient gel electrophoresis （DGGE） and 16S rRNA gene clone library, we concluded that the acidification process reduced the number of pathogenic bacteria species in pig manure.

Anaerobic co-digestion of sodium hydroxide pretreated sugarcane leaves with pig manure and dairy manure

Sugarcane leaves(SL)pretreated by alkali was used as substrate to enhance biogas production via mesophilic anaerobic digestion(AD)in this study.Effectiveness of different concentrations of NaOH pretreatment on AD performance was investigated.Results showed that compared to untreated sample of SL,the lignocellulose(LCH)content of NaOH pretreated group was decreased by 5.79%-16.85%.However,the cumulative biogas production of the pretreated samples increased in the range of 34.54%-82.67%;moreover,T90 was shorten by 5-7 d.The highest anaerobic digestibility of SL was achieved at 6%NaOH pretreatment,which produced 287.30 mL/g TS of biogas.A significant interactive effect of the three parameters(temperature,SL/manure mixing ratio and C/N ratio)was found on the biogasification of anaerobic co-digestion,and a maximum biogas production was achieved at 36.2oC,mixing ratio of 1.6 and C/N ratio of 29.2.These show that the verification experiment confirmed the optimization results.This study provides meaningful insight for exploring efficient pretreatment strategy and optimal condition to stabilize and enhance AD performance for practical application.

Cross-interaction of volatiles from co-pyrolysis of lignin with pig manure and their effects on properties of the resulting biochar

Biomass and pig manure have distinct compositions and the co-pyrolysis of them has gained much attention.However,the influence of volatiles interaction on the properties of the char was still unclear.In this study,lignin was selected as the model component of biomass with pig manure for co-pyrolysis at 600°C.The results indicate that volatiles from co-pyrolysis promoted re-condensation reaction,resulting in the higher char yield(48.0%in co-pyrolysis versus 31.0%in pyrolysis of single manure)and the formation of more aromatics in bio-oil.The co-pyrolysis also facilitated the dehydrogenation and dehydration reactions,which accounted for the elimination of oxygen and nitrogen contents and thus a higher carbon content(64.7%in the co-pyrolysis versus the averaged value of 46.4%from the pyrolysis of single feedstock),higher crystallinity and thermal stability of the char.The in-situ diffuse reflection infrared Fourier transform spectroscopy(DRIFTS)characterization results demonstrated that the functionalities abundances of char with temperature was influenced by volatiles interaction via accelerating the carbonization reaction.In addition,the high heating value(HHV)of char was obviously improved by cross-interaction of volatiles during co-pyrolysis(24.4 MJ/Kg in co-pyrolysis versus averaged value of 15.1 MJ/Kg from single pyrolysis),implying that the co-pyrolysis enhanced the energy density of the resulting char.

Core and variable antimicrobial resistance genes in the gut microbiomes of Chinese and European pigs

Monitoring the prevalence of antimicrobial resistance genes(ARGs)is vital for addressing the global crisis of antibiotic-resistant bacterial infections.Despite its importance,the characterization of ARGs and microbiome structures,as well as the identification of indicators for routine ARG monitoring in pig farms,are still lacking,particularly concerning variations in antimicrobial exposure in different countries or regions.Here,metagenomics and random forest machine learning were used to elucidate the ARG profiles,microbiome structures,and ARG contamination indicators in pig manure under different antimicrobial pressures between China and Europe.Results showed that Chinese pigs exposed to high-level antimicrobials exhibited higher total and plasmid-mediated ARG abundances compared to those in European pigs(P<0.05).ANT(6)-Ib,APH(3')-IIIa,and tet(40)were identified as shared core ARGs between the two pig populations.Furthermore,the core ARGs identified in pig populations were correlated with those found in human populations within the same geographical regions.Lactobacillus and Prevotella were identified as the dominant genera in the core microbiomes of Chinese and European pigs,respectively.Forty ARG markers and 43 biomarkers were able to differentiate between the Chinese and European pig manure samples with accuracies of 100%and 98.7%,respectively.Indicators for assessing ARG contamination in Chinese and European pigs also achieved high accuracy(r=0.72-0.88).Escherichia flexneri in both Chinese and European pig populations carried between 21 and 37 ARGs.The results of this study emphasize the importance of global collaboration in reducing antimicrobial resistance risk and provide validated indicators for evaluating the risk of ARG contamination in pig farms.

Nitrogen Mineralization from Animal Manures and Its Relation to Organic N Fractions

Laboratory aerobic incubation was conducted for 161 d to study N mineralization and the changes of organic N fractions of nine different manures（3 chicken manures, 3 pig manures and 3 cattle manures） from different farms/locations. Results indicated that significant（P〈0.01 or P〈0.001） difference existed in N mineralization between manures. The rapid N mineralization in manures occurred during 56 to 84 d of incubation. First order exponential model can be used to describe N mineralization from chicken manures and pig manures, while quadratic equation can predict mineralization of organic N from cattle manures. An average of 21, 19 and 13% added organic N from chicken manure, pig manure and cattle manure was mineralized during 161 d of incubation. Amino acid-N was the main source of N mineralization. The changes of amino acid-N together with ammonium N could explain significantly 97 and 96% of the variation in mineralized N from manured soils and manures. Amino acid-N and ammonium N are two main N fractions in determining N mineralization potential from manures. Amino acid-N contributed more to the mineralized N than ammonium N.

Antibiotic resistance genes in manure-amended paddy soils across eastern China:Occurrence and influencing factors

Pig manure,rich in antibiotics and metals,is widely applied in paddy fields as a soil conditioner,triggering the proliferation of antibiotic resistance genes(ARGs)in soil.However,comprehensive studies on the effects of manure fertilization on the abundance of ARGs and their influencing factors are still insufficient.Here,pig manure and manure-amended and inorganic-amended soils were collected from 11 rice-cropping regions in eastern China,and the accumulation of antibiotics,metals,and ARGs was assessed simultaneously.The results showed that manure fertilization led to antibiotic residues and increased the metal content(i.e.,Zn,Cu,Ni,and Cr).Tetracycline and sulfonamide resistance genes(tetM,tetO,sul1,and sul2)were also significantly enhanced with manure fertilization.According to variance partitioning analysis,the most important factors that individually influenced ARGs were soil physicochemical properties,accounting for 12%of the variation.Significant correlations between soil nutrients and ARGs indicated that manure application enhanced the growth of resistant microorganisms by supplying more nutrients.Metals and antibiotics contributed 9%and 5%to the variations in ARGs,respectively.Their co-occurrence also increased the enrichment of ARGs,as their interactions accounted for 2%of the variation in ARGs.Interestingly,Cu was significantly related to most ARGs in the soil(r=0.26–0.52,p<0.05).Sulfapyridine was significantly related to sul2,and tetracycline resistance genes were positively related to doxycycline.This study highlighted the risks of antibiotic and ARG accumulation with manure fertilization and shed light on the essential influencing factors of ARGs in paddy soils.