Implications of urine-to-feces ratio in the thermophilic anaerobic digestion of swine waste.

Thermophilic anaerobic digestion of swine manure represents a potential waste treatment technology to address environmental concerns, such as odor emissions and removal of pathogenic microorganisms. However, there are concerns relative to the stability of this process when swine manure is the sole substrate. In this study, the potential of biogas production from swine manure as the sole substrate under thermophilic (50 degrees C) conditions was investigated in the laboratory, to determine whether separation of urine and feces as part of the waste collection process would benefit anaerobic digestion. Effluent from a continuously stirred tank reactor was used as the inoculum for batch tests, in which the substrate contained three different concentrations of urine (urine-free, as-excreted urine-to-feces ratio and double the as-excreted urine-to-feces ratio). Inocula were acclimated to these same urine-to-feces ratios to determine methane production. Results show that both urine-free and as-excreted substrates were not inhibitory to anaerobic inocula. Anaerobic microorganisms can be readily acclimated to substrate with double the as-excreted urine concentration, which contained nitrogen concentrations up to 7.20 g/L. Cumulative methane production reached similar levels in the batch tests, regardless of the substrate urine concentration.     

Bioenergy production from diluted poultry manure and microbial consortium inside Anaerobic Sludge Bed Reactor at sub-mesophilic conditions

In this study, anaerobic treatability of diluted chicken manure (with an influent feed ratio of 1 kg of fresh chicken manure to 6 L of tap water) was investigated in a lab-scale anaerobic sludge bed (ASB) reactor inoculated with granular seed sludge. The ASB reactor was operated at ambient temperature (17–25°C) in order to avoid the need of external heating up to higher operating temperatures (e.g., up to 35°C for mesophilic digestion). Since heat requirement for raising the temperature of incoming feed for digestion is eliminated, energy recovery from anaerobic treatment of chicken manure could be realized with less operating costs. Average biogas production rates were calculated ca. 210 and 242 L per kg of organic matter removed from the ASB reactor at average hydraulic retention times (HRTs) of 13 and 8.6 days, respectively. Moreover, average chemical oxygen demand (COD) removal of ca. 89% was observed with suspended solids removal more than 97% from the effluent of the ASB reactor. Influent ammonia, on the other hand, did not indicate any free ammonia inhibition due to dilution of the raw manure while pH and alkalinity results showed stability during the study. Microbial quantification results indicated that as the number of bacterial community decreased, the amount of Archaea increased through the effective digestion volume of the ASB reactor. Moreover, the number of methanogens displayed an uptrend like archaeal community and a strong correlation (?0.645) was found between methanogenic community and volatile fatty acid (VFA) concentration especially acetate.     

The effect of anaerobic digestion and storage on indicator microorganisms in swine and dairy manure

The aim of this experimental study was to evaluate the influence of anaerobic digestion and storage on indicator microorganisms in swine and dairy excreta. Samples were collected every 90 days for 15 months at eight farms, four pig, and four dairy farms, four of them having a biogas plant. Moreover, to evaluate storage effects on samples, 20 l of manure and slurry taken at each farm (digested manure only in farms with a biogas plant) were stored in a controlled climatic chamber at 18 °C, for 6 months. The bacterial load and the chemical-physical characteristics of excreta were evaluated at each sampling time, stored slurry, and manure were sampled and analyzed every 2 months. A high variability of the concentration of bacteria in the different excreta types was observed during the experiment, mainly depending on the type and time of treatment. No sample revealed either the presence of Escherichia coli O157:H7 or of Salmonella, usually linked to the temporary rearing of infected animals in facilities. Anaerobic digestion and storage affected in a significant way the reduction of indicator bacteria like lactobacilli, coliforms, and streptococci. Anaerobic digestion lowered coliforms in pig slurry (? 2.80 log, P < 0.05), streptococci in dairy manure (? 2.44 log, P < 0.001) and in pig slurry (? 1.43 log, P < 0.05), and lactobacilli in pig slurry (? 3.03 log, P < 0.05). Storage lowered coliforms and the other indicators counts, in particular in fresh wastes, while clostridia did not show a reduction in concentration.     

Anaerobic digestion of livestock and poultry manures spiked with tetracycline antibiotics

Abstract

We investigated the anaerobic degradation of tetracycline antibiotics (tetracycline [TC], oxytetracycline [OTC] and chlortetracycline [CTC]) in swine, cattle, and poultry manures. The manures were anaerobically digested inside polyvinyl chloride batch reactors for 64?days at room temperature. The degradation rate constants and half-lives of the parent tetracyclines were determined following first-order kinetics. For CTC the fastest degradation rate was observed in swine manure (k?=?0.016?±?0.001 d^?1; half-life = 42.8?days), while the slowest degradation rate was observed in poultry litter (k?=?0.0043?±?0.001 d^?1; half-life = 161?days). The half-lives of OTC ranged between 88.9 (cattle manure) and 99.0?days (poultry litter), while TC persisted the longest of the tetracycline antibiotics studied with half-lives ranging from 92.4?days (cattle manure) to 330?days (swine manure). In general, the tetracyclines were found to degrade faster in cattle manure, which had the lowest concentrations of organic matter and metals as compared to swine and poultry manures. Our results demonstrate that tetracycline antibiotics persist in the animal manure after anaerobic digestion, which can potentially lead to emergence and persistence of antibiotic resistant bacteria in the environment when anaerobic digestion byproducts are land applied for crop production.     

Developing an anaerobic digester with external Zeolite filled column for enhancing methane production from swine manure – A feasibility study

ABSTRACT

Development of digesters with an external zeolite column facilitates the convenient removal of the zeolite with TAN, without disturbing the continuous anaerobic digestion process. A digester with an inside zeolite bed (In-Zeo) and digester without adding zeolite (No-Zeo) were employed to compare the process performance with digester with external zeolite column (EX-Zeo). The cumulative, CH₄ yields were 5% and 15% greater in the EX-Zeo, and the In-Zeo digesters respectively compared to the No-Zeo digesters. Also, the % VS reduction was 49%, 55% and 41%, respectively in the Ex-Zeo, In-Zeo and No-Zeo digesters. The results indicated that treatment with 7% zeolite during anaerobic digestion has the potential to improve biodegradation of swine manure. The addition of zeolite appeared to reduce TAN from the digestate, thereby enhancing the CH₄ yield. Zeolite could be used either internally or externally to enhance CH₄ production through anaerobic digestion of swine manure.     

Effect of potassium inhibition on the thermophilic anaerobic digestion of swine waste.

The inhibition effects of high potassium concentration on thermophilic anaerobic digestion of swine waste were studied. A continuous stirred tank reactor (CSTR), operated at a hydraulic retention time of 10 days and chemical oxygen demand loading of 7.2 to 7.5 g/L/d, was used to digest swine waste and cultivate thermophilic anaerobic microorganisms. To evaluate the toxicity of potassium, batch inhibition tests were also conducted. Without acclimation to potassium, the inhibition threshold beyond which methane production decreased significantly was 3 g K+/L. Volatile fatty acids accumulation was observed during the decline of methane production. Propionic acid was the dominant fatty acid, indicating that propionic acid utilizers were more sensitive to potassium inhibition than acetoclastic methanogens. To test the effect of acclimation on potassium inhibition, the potassium concentration in the CSTR was increased to 6 and 9 g K+/L. Acclimation to 6 g K+/L increased the tolerance of anaerobic inocula to potassium inhibition without significantly reducing the methanogenic activity. The inhibition threshold was increased from 3 g K+/L for unacclimated inocula, to 6 g K+/L for inocula acclimated to 6 g/L of potassium. Acclimation of inocula to 9 g/L potassium further increased the inhibition threshold to 7.5 g K+/L. However, the overall methanogenic activity in the last case was lower than that of unacclimated and 6 g K+/L acclimated inocula.     

Inhibition of residual <Emphasis Type="Italic">n</Emphasis>-hexane in anaerobic digestion of lipid-extracted microalgal wastes and microbial community shift

Converting lipid-extracted microalgal wastes to methane (CH₄) via anaerobic digestion (AD) has the potential to make microalgae-based biodiesel platform more sustainable. However, it is apparent that remaining n-hexane (C₆H₁₄) from lipid extraction could inhibit metabolic pathway of methanogens. To test an inhibitory influence of residual n-hexane, this study conducted a series of batch AD by mixing lipid-extracted Chlorella vulgaris with a wide range of n-hexane concentration (～10 g chemical oxygen demand (COD)/L). Experimental results show that the inhibition of n-hexane on CH₄ yield was negligible up to 2 g COD/L and inhibition to methanogenesis became significant when it was higher than 4 g COD/L based on quantitative mass balance. Inhibition threshold was about 4 g COD/L of n-hexane. Analytical result of microbial community profile revealed that dominance of alkane-degrading sulfate-reducing bacteria (SRB) and syntrophic bacteria increased, while that of methanogens sharply dropped as n-hexane concentration increased. These findings offer a useful guideline of threshold n-hexane concentration and microbial community shift for the AD of lipid-extracted microalgal wastes.     

Biohydrogen production from dairy manures with acidification pretreatment by anaerobic fermentation

Background, aim, and scope  

Hydrogen is a clean and efficient energy source and has been deemed as one of the most promising carriers of new energy for the future. From an engineering point of view, producing hydrogen by mixed cultures is generally preferred because of lower cost, ease of control, and the possible use of organic waste as feedstock. The biological hydrogen production has been intensively studied in recent decades. So far, most investigates of biohydrogen production are still confined to using pure carbohydrates and carbohydrate-rich wastewater. Nowadays, the large amounts of livestock manure, which come from cattle feedlots, poultry, and swine buildings, are causing a major environmental issue because it has become a primary source of odors, gases, dust, and groundwater contamination. The increasingly stringent requirements for pollution control on livestock manures are challenging the scientific community to develop new waste treatment strategies. Thus, there is a pressing need to develop nonpolluting and renewable energy source utilizing the organic waste (e.g., livestock manure). It is well known that anaerobic digestion had successfully been used for the disposal of manures to produce methane in the last two decades. Recently, an alternative strategy has been developed to convert livestock manures (e.g., dairy manures) to biohydrogen as a high value-added clean energy source instead of methane. However, little information is available on hydrogen production from dairy manure via the mixed anaerobic microbe. As far as we know, the hydrogen production is habitually accompanied with production of volatile fatty acids (VFAs), such as acetate, butyrate, and propionate, which are also an optimal feedstock for production of methane by anaerobic digestion. Provided that the biohydrogen production from dairy manure is further combined with the anaerobic digestion of the effluent from the producing hydrogen reactor that would be a one-stone two-bird paradigm, it not only produces a clean and readily usable biologic energy but also cleans up simultaneously the environment in a sustainable fashion.     

Optimization of animal manure vermicomposting based on biomass production of earthworms and higher plants

The goal of this study was to optimize the mixture of swine manure (SM) and cattle manure (CM) used in the vermicomposting process, seeking to increase the manure biodegradation rate and enhance the biomass production of both earthworms and higher plants. To achieve this goal, physico-chemical parameters were determined to assess the final compost quality after 50 days of vermicomposting. The different manure ratios used to produce the composts (C) were as follows (SM:CM, % m/m basis): C1 100:0, C2 (75:25), C3 (50:50), C4 (25:75), and C5 (0:100). In addition, the earthworm biomass and the phytoproductivity of lettuce (Lactuca sativa L.) plants grown in mixtures (1:1) of natural soil and the most viable vermicomposts were investigated. The C1 and C2 compost compositions were associated with high earthworm mortality rates. The C3 compost provided the highest mineral concentrations and C5 showed the highest lettuce yield (wet biomass). The results verify that stabilized cattle manure is an excellent substrate for the vermicomposting process and that fresh swine manure must be mixed with pre-stabilized cattle manure to ensure an optimized vermicomposting process, which must be controlled in terms of temperature and ammonia levels. It is concluded that small livestock farmers could add value to swine manure by applying the vermicomposting process, without the need for high investments and with a minimal requirement for management of the biodegradation process. These are important technical aspects to be considered when circular economy principles are applied to small farms.     

Effect of green manure amendment on herbicide pendimethalin on soil

Manure amendment in agricultural practice can have a large effect on herbicide dissipation because the period of manure plowing is close to the period of herbicide application. In addition, manure amendment is among the frequently encountered options in ameliorating pesticide pollution. In this research, the dissipation of the herbicide pendimethalin was examined after amendment with two common green manures, Lupinus luteus (L) or Cosmos bipinnatus (C), for 110 days in pH 5.2 and 7.7 soils (Sankengtzu [Sk] and Erhlin [Eh] soil, respectively). The microbial activity and ecology changes were examined by using Biolog EcoPlate and denaturing gradient gel electrophoresis (DGGE). In Sk soil, the half-lives of pendimethalin with L, C, and blank treatment were 49.0, 54.9, and 62.2 days, respectively, whereas that in Eh soil they were 46.3, 52.6, and 34.8 days, respectively. Pendimethalin dissipated quickly in more neutral soil (Eh soil), but the addition of manure can only increase the dissipation rate in acidic soil (Sk soil), indicating that the amendment of manures exerted different effect in pendimethalin dissipation rates in different pH soils. The application of pendimethalin and/or manure altered the microbial community activity after 24 h of incubation. After 110 days, the microbial community activities in green manure–amended soil were more similar to that with blank than pendimethalin treatment in both types of soils. In comparison with treatment C, microbial communities were more similar between treatment L and blank, indicating the superior effect over pendimethalin on microbial communities when applying Lupinus luteus. The research showed that the application of herbicide pendimethalin changed soil microbial community, and the amendment of manures exerted different effect in pendimethalin dissipation rates in different pH soils. It is assumed that the change in dissipation rates was originated from the microbial community change after different manure amendment.     

A novel use of anaerobically digested liquid swine manure to potentially control soybean cyst nematode

Experiments were carried out in two steps to determine the effect of anaerobically digested swine manure on soybean cyst nematode (SCN) egg control. In the first step, liquid swine manure underwent anaerobic digestion to search for the best digestion time for both volatile fatty acids (VFA) and ammonium nitrogen (NH(4)(+)) enrichment. The results showed that about 17 and 28 days of incubation were needed, respectively, to reach the maximal levels of VFA and NH(4)(+) in the manure. In the second step, raw, VFA-enriched, and NH(4)(+)-enriched manure were applied separately, at four different rates (25, 50, 100, and 200 mL/pot), to soil pots inoculated with nematode eggs in a greenhouse environment. Soil samples were collected 35 and 61 days after inoculation to determine the effect of such treated manure on SCN egg productivity. The data indicated that the SCN egg counts were inversely related to the manure application rates in a linear manner with correlation coefficients of 0.998, 0.967, and 0.900 for raw, NH(4)(+)-enriched, and VFA-enriched manure for the 35-day samples. While no such relationships were found for the 61-day samples, implying that none of the treatments were still effective 61 days after application. At the four application rates, the VFA-enriched manure performed best in reducing SCN egg counts (by 18.1, 19.5, 34.3, and 18.6%) as compared to the raw manure treatment. In contrast, the NH(4)(+)-enriched manure achieved mostly negative reductions. To achieve the best control of SCN egg growth, the VFA-enriched manure should be used and applied to soybean fields every 35 days.     

Adsorption characteristics of Cu(II) from aqueous solution onto biochar derived from swine manure

The purpose of this study was to investigate adsorption characteristic of swine manure biochars pyrolyzed at 400 °C and 700 °C for the removal of Cu(II) ions from aqueous solutions. The biochars were characterized using BET surface area, Fourier transform infrared spectroscopy (FTIR), zeta potential, scanning electron microscopy/energy dispersive spectrometer (SEM–EDS), and X-ray diffraction (XRD). The adsorption of Cu(II) ions by batch method was carried out and the optimum conditions were investigated. The adsorption processes of these biochars are well described by a pseudo-second-order kinetic model, and the adsorption isotherm closely fitted the Sips model. Thermodynamic analysis suggested that the adsorption was endothermic. The maximum Cu(II) adsorption capacities of biochars derived from fresh and composted swine manure at 400 °C were 17.71 and 21.94 mg g^?1, respectively, which were higher than those at 700 °C. XRD patterns indicated that the silicate and phosphate particles within the biochars served as adsorption sites for Cu(II). The removal of Cu(II) ions from industrial effluent indicated that the fresh swine manure biochar pyrolyzed at 400 °C can be considered as an effective adsorbent.     

The effect of Mg<Superscript>2+</Superscript> on digestion performance and microbial community structures in sludge digestion systems

The important criteria in anaerobic digestion is the rate-limiting step which decides the fate of value-added products especially from waste-activated sludge (WAS). Hence, the present study investigated the effect of magnesium (Mg²⁺) addition on anaerobic digestion of WAS. The lab-scale experiments were conducted at 25 °C with Mg²⁺ doses ranging from 0.01 to 0.2 mol/L. Maximum total volatile fatty acids (VFAs) production (372.78 mg COD/L) occurred at a Mg²⁺ dose of 0.2 mol/L, which was about eight times higher than the control tests. Further, Mg²⁺ addition facilitated sludge dewaterability and phosphorus removal. The mechanism of improved VFAs generation was analyzed from the view of both chemical and biological effects. Chemical effect significantly enhanced the release of calcium and iron in WAS, resulting in the disintegration of WAS, which benefited hydrolysis and acidification processes. Illumina MiSeq sequencing analysis revealed that enrichment of functional bacteria and the increase of bacterial diversity were obtained in the 0.2 mol Mg²⁺/L experiment, while the influence was negative on the reactor with 0.025 mol/L Mg²⁺. Meanwhile, methanogens were accordantly inhibited in the experiments with Mg²⁺ addition.     

A novel use of anaerobically digested liquid swine manure to potentially control soybean cyst nematode

Experiments were carried out in two steps to determine the effect of anaerobically digested swine manure on soybean cyst nematode (SCN) egg control. In the first step, liquid swine manure underwent anaerobic digestion to search for the best digestion time for both volatile fatty acids (VFA) and ammonium nitrogen (NH₄ ⁺) enrichment. The results showed that about 17 and 28 days of incubation were needed, respectively, to reach the maximal levels of VFA and NH₄ ⁺ in the manure. In the second step, raw, VFA-enriched, and NH₄ ⁺-enriched manure were applied separately, at four different rates (25, 50, 100, and 200 mL/pot), to soil pots inoculated with nematode eggs in a greenhouse environment. Soil samples were collected 35 and 61 days after inoculation to determine the effect of such treated manure on SCN egg productivity. The data indicated that the SCN egg counts were inversely related to the manure application rates in a linear manner with correlation coefficients of 0.998, 0.967, and 0.900 for raw, NH₄ ⁺-enriched, and VFA-enriched manure for the 35-day samples. While no such relationships were found for the 61-day samples, implying that none of the treatments were still effective 61 days after application. At the four application rates, the VFA-enriched manure performed best in reducing SCN egg counts (by 18.1, 19.5, 34.3, and 18.6%) as compared to the raw manure treatment. In contrast, the NH₄ ⁺-enriched manure achieved mostly negative reductions. To achieve the best control of SCN egg growth, the VFA-enriched manure should be used and applied to soybean fields every 35 days.     

挥发性脂肪酸对厌氧干式发酵产甲烷的影响

为了提高中温干式厌氧间歇发酵效率,研究了发酵过程中间产物———挥发性脂肪酸对产甲烷的影响。实验分2批进行,第1批在牛粪发酵过程中分别添加乙酸、丙酸和丁酸,第2批发酵添加易产生挥发酸的厨余垃圾混合发酵。结果显示,添加单一挥发酸的发酵过程中,添加丙酸的产甲烷速度较慢,因为丙酸降解生成乙酸的速度较慢,减慢了甲烷的形成;混合发酵过程厨余垃圾产甲烷速度比牛粪快,发酵过程产生2个产气高峰;牛粪和厨余垃圾固体物质含量比在11∶1到5∶1范围内较好,比牛粪单独发酵产气多,产酸高但不酸败,产生的挥发酸主要是乙酸和丙酸,其中比例为7∶1混合发酵的产甲烷速率最大,为4.89 mL/(g VS·d)。实验表明,牛粪厌氧干式发酵过程添加一定量的厨余垃圾可加快挥发酸的产生并提高挥发酸产量,从而提高甲烷的产量,但是总挥发酸长时间超过10 000 mg/L,pH降到不适于产甲烷菌生长的范围时,将抑制甲烷的生成,挥发酸积累导致厌氧发酵酸败。     

Pilot‐scale field study for ammonia removal from lagoon biogas using an acid wet scrubber

The anaerobic activities in swine slurry storage and treatment generate biogas containing gaseous ammonia component which is a chemical agent that can cause adverse environmental impacts when released to the atmosphere. The aim of this pilot plant study was to remove ammonia from biogas generated in a covered lagoon, using a sulfuric acid wet scrubber. The data showed that, on average, the biogas contained 43.7 ppm of ammonia and its concentration was found to be exponentially related to the air temperature inside the lagoon. When the air temperature rose to 35°C and the biogas ammonia concentration reached 90 ppm, the mass transfer of ammonia/ammonium from the deeper liquid body to the interface between the air and liquid became a limiting factor. The biogas velocity was critical in affecting ammonia removal efficiency of the wet scrubber. A biogas flow velocity of 8 to 12 mm s^?1 was recommended to achieve a removal efficiency of greater than 60%. Stepwise regression revealed that the biogas velocity and air temperature, not the inlet ammonia concentration in biogas, affected the ammonia removal efficiency. Overall, when 73 g L^?1 (or 0.75 M) sulfuric acid solution was used as the scrubber solution, removal efficiencies varied from 0% to 100% with an average of 55% over a 40‐d measurement period. Mass balance calculation based on ammonium–nitrogen concentration in final scrubber liquid showed that about 21.3 g of ammonia was collected from a total volume of 1169 m³ of biogas, while the scrubber solution should still maintain its ammonia absorbing ability until its concentration reaches up to 1 M. These results showed promising use of sulfuric acid wet scrubber for ammonia removal in the digester biogas.     

Humic acids enhance the microbially mediated release of sedimentary ferrous iron

Iron (Fe) is an essential element for many organisms, but high concentrations of iron can be toxic. The complex relation between iron, arsenic (As), bacteria, and organic matter in sediments and groundwater is still an issue of environmental concern. The present study addresses the effects of humic acids and microorganisms on the mobilization of iron in sediments from an arsenic-affected area, and the microbial diversity was analyzed. The results showed that the addition of 50, 100, and 500 mg/L humic acids enhanced ferrous iron (Fe(II)) release in a time-dependent and dose-dependent fashion under anaerobic conditions. A significant increase in the soluble Fe(II) concentrations occurred in the aqueous phases of the samples during the first 2 weeks, and aqueous Fe(II) reached its maximum concentrations after 8 weeks at the following Fe(II) concentrations: 28.95?±?1.16 mg/L (original non-sterilized sediments), 32.50?±?0.71 mg/L (50 mg/L humic acid-amended, non-sterilized sediments), 37.50?±?1.85 mg/L (100 mg/L humic acid-amended, non-sterilized sediments), and 39.00?±?0.43 mg/L (500 mg/L humic acid-amended, non-sterilized sediments). These results suggest that humic acids can further enhance the microbially mediated release of sedimentary iron under anaerobic conditions. By contrast, very insignificant amounts of iron release were observed from sterilized sediments (the abiotic controls), even with the supplementation of humic acids under anaerobic incubation. In addition, the As(III) release was increased from 50?±?10 μg/L (original non-sterilized sediments) to 110?±?45 μg/L (100 mg/L humic acid-amended, non-sterilized sediments) after 8 weeks of anaerobic incubation. Furthermore, a microbial community analysis indicated that the predominant class was changed from Alphaproteobacteria to Deltaproteobacteria, and clearly increased populations of Geobacter sp., Paludibacter sp., and Methylophaga sp. were found after adding humic acids along with the increased release of iron and arsenic. Our findings provide evidence that humic acids can enhance the microbially mediated release of sedimentary ferrous iron in an arsenic-affected area. It is thus suggested that the control of anthropogenic humic acid use and entry into the environment is important for preventing the subsequent iron contamination in groundwater.     

Tylosin sorption to silty clay loam soils, swine manure, and sand

The objectives of this study were to assess sorption and desorption of tylosin, a macrolide antimicrobial chemical used in swine, cattle, and poultry production, in three silty clay loam soils of South Dakota and compare soil sorption to sand and manure sorption. The silty clay loam soils, from a toposequence in eastern South Dakota, standardized sand samples, and swine manure were used in 24-h batch sorption studies with tylosin concentrations ranging from 25 to 232 micro mole/L. Desorption from soil was conducted over a four-day period. Partition coefficients, based on the Freundlich isotherm (K(f)) or K(d) values, were calculated. K(f) values for the silty clay loams were similar, not influenced by landscape position, and averaged 1,350 with isotherm slopes ranging from 0.85 to 0.93. K(f) values for sand were dependent on solution/sand ratios and pH, ranging from 1.4 to 25.1. K(d) values of manure were dependent on the solution type and ranged from 840 L/kg with urine to about 175 L/kg when sorbed from water. Desorption of tylosin from each soil over the four-day period was < 0.2% of the amount added. The soils' high K(f) values and low desorption amounts suggest that once tylosin is in these soils, leaching to lower depths may not occur. However, this does not preclude runoff with soil eroded particles. If tylosin reaches a sand aquifer, through bypass flow or other mechanism(s), movement in the aquifer most likely would occur.     

Bacteria additives to the changes in gaseous mass transfer from stored swine manure

Abstract

A bacteria additives treatment experiment in assessing the changes in gaseous mass transfer from stored swine manure is presented. The experiment is tested for ammonia, methane, hydrogen sulfide, and carbon dioxide emission data sampled from pilot swine manure columns and analyzed by GC/MS. The result shows that bacteria additives slightly reduce the methane and carbon dioxide releases, while the same additives do not show any effect on the reduction of ammonia. The hydrogen sulfide contents of stored swine manure continued to be low. Gas concentrations emitted from treated and untreated stored swine manure were: 3.76 and 2.2 ppm for methane, 0.35 and 0.11 ppm for ammonia, and 1000 and 470 ppm for carbon dioxide, respectively. A simple model to estimate gas emission rates is also developed from the viewpoint of two‐film resistance theory. The average emission rates calculated from the model for methane, ammonia, and carbon dioxide are respectively: 0.01, 0.0005, and 13.98 g/min from untreated stored manure; while 0.07, 0.096, and 0.55 g/min from treated manure. The emission model also indicates that for most gaseous pollutants of environmental concern, liquid phase transfer coefficient controls the rate of volatile compounds emitted from stored swine manure and gas phase transfer coefficient has insignificant effect in the calculation of overall mass transfer coefficient.