Gas Washing Research Articles

Origin of late charged gas and its effect on property of oils in the Ordovician in Tazhong area

Abstract Natural gases in Ordovician reservoirs of the Tazhong area of the Tarim Basin appear derived by oil-cracking gas. The gases show very different geochemical characteristics. Most of the gases in the middle and eastern part of the No. 1 fault-slope zone are characterized by high gas dryness coefficients and have methane δ 13 C 1 values heavier than primary gas. These features are different from gases in the western part of the No. 1 fault-slope zone. Thus, we propose that there existed mixing between more mature, 13 C-rich methane dominated gas and less mature wet gas with 13 C-depleted methane. The hypothesis is supported by (1) roughly a positive correlation between the gas dryness coefficient and methane δ 13 C 1 value, (2) significantly heavier δ 13 C 1 values in the eastern part of the study area than in the west, and (3) significantly heavier δ 13 C 1 values than anticipated for unaltered gas co-generated with C 2 –C 4 . The charge and mixing of the dry gas into the Ordovician pools may have resulted in increase in wax contents of the oils, gas/oil ratios, gas dryness coefficients and methane δ 13 C values, leading to a positive correlation between gas/oil ratio and paraffin wax content as a result of continuous fractionation and removal of light components of an oil with progressive gas influx and thus gas washing.

Evidence for a palaeo-oil column and alteration of residual oil in a gas-condensate field: Integrated oil inclusion and experimental results

In the Phuong Dong gas condensate field, Cuu Long Basin, Vietnam, hydrocarbon inclusions in quartz trapped a variety of petroleum fluids in the gas zone. Based on the attributes of the oil inclusion assemblages (fluorescence colour of the oil, bubble size, presence of bitumen), the presence of a palaeo-oil column is inferred prior to migration of gas into the reservoir. When a palaeo-oil column is displaced by gas, a residual volume fraction of oil remains in pores. If the gas does not completely mix with the oil, molecular partitioning between the residual oil and the new gas charge may change the composition and properties of the residual oil (gas stripping or gas washing). To simulate this phenomenon in the laboratory, we sealed small amounts of crude oil (42 and 30°API) and excess pure gas (methane, ethane, or propane) in fused silica capillary capsules (FSCCs), with and without water. These mixtures were characterized with the same methods used to characterize the fluid inclusions, heating and cooling stage microscopy, fluorescence spectroscopy, synchrotron FT-IR, and Raman spectroscopy. At room temperature, mixtures of ethane and propane with the 30°API oil formed a new immiscible fluorescent liquid phase with colour that is visually more blue than the initial oil. The fluorescence of the original oil phase shifted to yellow or disappeared with formation of semi-solid residues. The blue-shift of the fluorescence of the immiscible phases and strong CH stretching bands in FT-IR spectra are consistent with stripping of hydrocarbon molecules from the oil. In experiments in FSCCs with water solid residues are common. At elevated temperature, reproducing geologic reservoir conditions, the fluorescence changes and therefore the molecular fractionation are enhanced. However, the precipitation of solid residues is responsible of more complex changes. Mixing experiments with the 42°API oil do not form a new immiscible hydrocarbon liquid although the fluorescence displays a similar yellow shift when gas is added. Solid residues rarely form in mixtures with 42°API oil. FT-IR spectra suggest that the decrease of fluorescence intensity of the original oil at short wavelengths to be due to the partitioning of low molecular weight aromatic molecules into the vapour phase and/or the new immiscible liquid phase. The decrease of fluorescence intensity at long wavelengths appears to be due to loss of high molecular weight aromatics during precipitation of solid residues by desorption of aromatics and resins from asphaltenes. Desorption of low molecular weight aromatics and resins from asphaltenes during precipitation can also increase the fluorescence intensity at short wavelengths of the residual oil. Water clearly affects the precipitation of semi-solid residues from the oil phase of the lowest API gravity oil.The change of hydrocarbon phase(s) in UV–visible fluorescence and FT-IR enclosed within the FSCCs were compared with the fluorescence patterns of natural fluid inclusions at Phuong Dong gas condensate field. The experimental results support the concept of gas-washing of residual oil and are consistent with the oil inclusion attributes from the current gas zone at Phuong Dong field. The hydrocarbon charge history of the fractured granite reservoir is interpreted to result from the trapping of residual oil after drainage of a palaeo-oil column by gas.

Discussion on Ship Exhaust Gas Washing Desulfurization Technology

With the continuous development of shipping industry, exhaust gas p-ollution caused by ship emissions of sulfur dioxide is increasingly serious. In o-rder to meet the international maritime organizations (IMO) strict requirements on the water shipping environment, much attention of flue gas desulfurization technology research has been paid. But the ship desulfurization wastewater research is relatively little, water quality analysis and processing system of flue gas desulfurization wastewater research should be carried out. This paper mainly introduces the principle and characteristics of seawater desulfurization process, research and application status of seawater desulfurization method. Discussing the application of sea water desulfurization on the ship for Marine diesel engine tail gas treatment in order to meet the requirements of the international maritime organization and meet the relevant national laws and the main problems to be solved, including the optimal amount of spray, desulfurization tower circulation surface model, installed on the ship. It also points out that the study of sea water desulfurization technique applied in ship's urgency and application prospect.

Characteristics and Accumulation Mechanism of Quasi-Layered Ordovician Carbonate Reservoirs in the Tazhong Area, Tarim Basin

Weathered crust reservoirs of marine carbonate rocks and large-area quasi-layered carbonate reservoirs controlled by massive unconformity surfaces have become an important play for exploration of marine hydrocarbons across China. In the Tazhong area, oil and gas originating from the marine facies of the Ordovician Yingshan formation, present large-scale integrated continuous accumulation along massive structures. In particular, they are accumulated continuously in layered form in carbonate fracture-cavity reservoir system, and not controlled by tertiary structural belts. Moreover, the Yingshan reservoirs are complex in types, comprising cross distribution of high gas/oil ratio (GOR) condensate gas reservoirs, volatile oil reservoirs and normal oil reservoirs, and large burial depth span and high heterogeneity of quasi-layered reservoirs. The complexity in diagenesis and accumulation lead to the unique distribution and enrichment of carbonate reservoirs in the Tazhong area. The analysis of blow-down and leakage depths, heterogeneity, and physical properties of pores, caves and fractures of the Yingshan formation carbonate reservoirs indicates that the interstratal karsts have superimposed with faults and fractures to form fracture zones, so that the reservoir bodies present integrated continuous distribution characteristics spatially, providing favorable conditions for quasi-layered continuous enrichment of oil and gas. During late periods, a massive amount of natural gas had been filled along the gas-source faults. Based on the variations of relative contents of light hydrocarbons and aromatic naphthalene homologs in crude oil, it is found that the quasi-layered continuous carbonate reservoirs in the Tazhong area are different in terms of the properties of oil and gas and the types of oil reservoirs as a result of the formation of high GOR high-yield condensate gas reservoirs near the oil/gas-source faults due to gas washing, migration and fractionation. Late gas charge and transformation process acting on earlier oil reservoirs is an important geochemical action in the formation mechanism of carbonate reservoirs in the Tazhong area.

Alteration and multi-stage accumulation of oil and gas in the Ordovician of the Tabei Uplift, Tarim Basin, NW China: Implications for genetic origin of the diverse hydrocarbons

The Ordovician is the most important exploration target in the Tabei Uplift of the Tarim Basin, which contains a range of petroleum types including solid bitumen, heavy oil, light oil, condensate, wet gas and dry gas. The density of the black oils ranges from 0.81 g/cm3 to 1.01 g/cm3 (20 °C) and gas oil ratio (GOR) ranges from 4 m3/m3 to 9300 m3/m3. Oil-source correlations established that most of the oils were derived from the Mid-Upper Ordovician marine shale and carbonate and that the difference in oil properties is mainly attributed to hydrocarbon alteration and multi-stage accumulation. In the Tabei Uplift, there were three main periods of hydrocarbon accumulation in the late Caledonian stage (ca. 450–430 Ma), late Hercynian stage (ca. 293–255 Ma) and the late Himalayan stage (ca. 12–2 Ma). The oil charging events mainly occurred in the late Caledonian and late Hercynian stage, while gas charging occurred in the late Hercynian stage. During the late Caledonian stage, petroleum charged the reservoirs lying east of the uplift. However, due to a crustal uplifting episode in the early Hercynian (ca. 386–372 Ma), most of the hydrocarbons were transformed by processes such as biodegradation, resulting in residual solid bitumen in the fractures of the reservoirs. During the late Hercynian Stage, a major episode of oil charging into Ordovician reservoirs took place. Subsequent crustal uplift and severe alteration by biodegradation in the west-central Basin resulted in heavy oil formation. Since the late Himalayan stage when rapid subsidence of the crust occurred, the oil residing in reservoirs was exposed to high temperature cracking conditions resulting in the production of gas and charged from the southeast further altering the pre-existing oils in the eastern reservoirs. A suite of representative samples of various crude oils including condensates, lights oils and heavy oils have been collected for detailed analysis to investigate the mechanism of formation. Based on the research it was concluded that the diversity of hydrocarbon physical and chemical properties in the Tabei Uplift was mainly attributable to the processes of biodegradation and gas washing. The understanding of the processes is very helpful to predict the spatial distribution of hydrocarbon in the Tabei Uplift and provides a reference case study for other areas.

Environmental exposure and flux of thallium by industrial activities utilizing thallium-bearing pyrite

Thallium (Tl) is a typical toxic heavy metal, with higher toxicity to mammals than Hg, Cd, and Pb. Accurate assessments of its environmental exposure and flux are central to effective management and control of Tl pollution. This paper first presents in detail the environmental exposure and flux of Tl by typical industrial activities utilizing Tl-bearing pyrite minerals to produce sulfuric acid. For this purpose, sequential extraction and Inductively Coupled Plasma Mass Spectrometry (ICP-MS) were used to investigate total content and geo-chemical partitioning of Tl in raw pyrite ores and solid roasting wastes, thereby uncovering Tl distribution and transformation during the production process. Results showed that some portions of Tl bearing in the minerals went into vapor, which transferred Tl into different processes; and some portions of Tl went into water during the gas washing procedure, leaving some other portions remained in the solid slags. More importantly, detailed investigation revealed that 40% of Tl in the pyrite minerals was active, among which 25% of Tl originally in the pyrite minerals was washed into water during gas cleaning process and 15% of active Tl retained in the slags. The latter portion of active Tl could be possibly transferred to the soil or water with the slag deposal or being reused; and 60% of Tl remained relatively stable in the residual phase.

Bio-desulfurization and denitrification by anaerobic-anoxic process for the treatment of wastewater from flue gas washing

For amine-based carbon dioxide capture, nitrogen oxides and sulfur oxides were the main pollutants that had a negative effect on the regeneration of solvent. Before carbon dioxide capture, the sulfur oxides in flue gas should be removed by the method of calcium salt, and then washed by alkaline solution to eliminate the residual nitrogen oxides and sulfur oxides. The washing wastewater containing sulfate and nitrate needs to be treated. In this study, a novel anaerobic-anoxic process was built up for the treatment of this washing wastewater. Nitrate was reduced to nitrogen by denitrifying bacteria. Sulfate was firstly reduced to sulfide by sulfate reducing bacteria, and then selectively oxidized to element sulfur by sulfide oxidizing bacteria. The treated liquid could be reused as absorption after the adjustment of pH value. The performances of this bioprocess were investigated under various pH values and S/N ratios. It was found that the optimal pH value of influent was 6.0, the percentages of denitrification and sulfate reducing could reach 90 and 89%, respectively. Seventy-six percent of sulfate was transformed into element sulfur. Nitrate significantly had a negative effect on sulfate reduction above 10 mM. As 20 mM nitrate, the sulfate reducing percentage would drop to 67%. These results showed that the anaerobic-anoxic process was feasible for the treatment of flue gas washing wastewater. It would be prospectively applied to other wastewater with the higher ratio of SO4(2-)/NO3(-).

VUV photolysis of naphthalene in indoor air: Intermediates, pathways, and health risk

To evaluate the health risk of vacuum ultraviolet (VUV) photolysis of naphthalene (NP) in indoor air, intermediates were detected by gas chromatograph–mass spectrometry and proton transfer reaction-mass spectrometry. Results showed that 13 volatile organic compounds (VOCs) in gas phase and five semi-volatile organic compounds (SVOCs) in oil phase were the main intermediates. VUV photolysis pathways of NP can be divided into five stages including functionalization, partition, condensation, fragmentation, and mineralization. Initially NP was converted into several SVOCs via functionalization by oxidative radicals. SVOCs with high boiling points and polarity groups would partition between aerosol and gas phase. Certain amount of SVOCs in aerosol phase were transformed to oily substances by condensation, which can be washed out by conventional gas washing technique like wet scrubber easily. A majority of SVOCs in gas phase were converted to VOCs by fragmentation, which can be further mineralized into CO2. The accumulation of VOCs, especially highly harmful aldehydes, resulted in an increase of health risk influence index (η) to 150 after VUV irradiation of 2.81min, while the mineralization of VOCs led to a sharp decline of η to 28 after VUV irradiation of 7.01min. It can be concluded that the mineralization of VOCs is a key factor to alleviate the health risk of photolysis. The results will guide a safe and economical application of VUV photolysis technology in indoor air purification.

Failure analysis of spiral finned tube on the economizer

This article describes the results of an investigation about the failure of spiral finned tube on a newly designed and retrofitted low pressure economizer in a 300MW pulverized-coal-fired power plant. In order to find out the failure causes and to suggest preventive measures, phase compositions and macrostructure of the tube metal surface were investigated by X-Ray Diffraction and Scanning Electron Microscope equipped with energy dispersive X-Ray spectroscopy micro-analysis. The results show that the failure was principally owing to comprehensive multiphase erosion, an interaction of the fly ash wearing, flue gas washing and sulfurous acid corrosion. Recommendations are given to minimize such failures.

Quantitative assessment and significance of gas washing of oil in Block 9 of the Tahe Oilfield, Tarim Basin, NW China

Some Ordovician and Triassic oils in Block 9 are characterized by light oils, which have distinctly differentiated from heavy oils in other blocks in the Tahe Oilfield, Tarim Basin. Based on the whole oil gas chromatograms, this paper estimates the effect of oil migration and fractionation and the amount of depletion (Q) in terms of the n-alkanes depletion model. The results showed that the amount of depletion in the Ordovician reservoir is highest in the east of this block, e.g. the depletion is 97% in Well T904. The amount of Q gets lower to the west, e.g. the depletion is 53.4% in Well T115 and there is no sign of depletion in Well S69. It is suggested that the direction of gas washing is from the east to the west. The compositions and isotopic characteristics of associated gas in Ordovician oils indicated that the gas might be derived from Cambrian source rocks of the Caohu Depression which lies to the east of Block 9. In contrast, no obvious depletion of n-alkanes in Triassic oils was found, suggesting that the migration pathway of natural gas has been limited to the Ordovician karst fracture system formed in the Early Hercynian Orogeny. Different depletions of the Ordovician and Triassic oils can reveal fault activities in this region.

Geochemistry of Palaeozoic marine petroleum from the Tarim Basin, NW China: Part 3. Thermal cracking of liquid hydrocarbons and gas washing as the major mechanisms for deep gas condensate accumulations

The Lunnan Lower Uplift in the Tarim Basin, NW China contains a composite petroleum system with mainly biodegraded heavy oil in the west, normal oil in the center and gas condensate in the east. Twenty-three gas samples and 37 oil samples taken from three major hydrocarbon bearing intervals in the Lunnan lower bulge were analyzed for their stable carbon isotopes and molecular biomarkers. On the basis of their isotopic compositions, biomarkers, especially diamondoids, and integrating the physical properties of the hydrocarbons including densities, GOR and PVT relationships, it has been concluded that the recently discovered deep (6500 m) eastern Lungu giant Ordovician gas condensate pool with an estimated reserve of 723 million bbl oil equivalent is a secondary hydrocarbon accumulation derived from the mixing of an early formed oil and a late formed gas. The extremely dry gases with a gas dryness of >0.98 were derived from thermal cracking of crude oils and charged to an existing oil reservoir causing extensive gas washing and secondary alteration. Compared with most of the hydrocarbons in the Lunnan area, the gas from the eastern Lungu gas condensate pool has a heavier carbon isotopic composition, higher dryness and a higher maturity level. The unique physical, chemical and isotopic compositions of the gas condensate are believed to be a direct result of gas flushing of an early formed eastern Lungu oil pool by a late formed dry gas from oil cracking. The eastern Lungu gas condensate pool is presently characterized by containing “dry gas, heavy oil, abundant aromatics and high wax”.

Hydrocarbon enrichment characteristics and difference analysis in the TZ1–TZ4 well block of the Tarim Basin

The reservoirs in the TZ1–TZ4 well block of the Tarim Basin are complex, and the hydrocarbon enrichment shows differences. The three Carboniferous oil layers are characterized by “oil in the upper and lower layers and gas in the middle” in profile and “oil in the west and gas in the east” in plane view. In order to discuss the complex reservoir accumulation mechanisms, based on the petroleum geology and reservoir distribution, we studied the generation history of source rocks, the fault evolution and sealing, the accumulation periods and gas washing, and reconstructed the accumulation process of the TZ1–TZ4 well block. It is concluded that the hydrocarbon enrichment differences of oil layers CIII, CII and CI were caused by multiple sources and multi-period hydrocarbon charging and adjustment. The CII was closely related to CIII, but CI was formed by reservoir adjustment during the Yanshan period and was not affected by gas washing after it was formed. During the Himalayan period, different degrees of gas washing in the east and west led to hydrocarbon enrichment differences on the plane. The Carboniferous accumulation process of two-stage charging and one-stage adjustment is summarized: oil charging during the late Hercynian period is the first accumulation period of CIII and CII; oil reservoirs were adjusted into CI in the Yanshan period; finally gas washing in the Himalayan period is the second accumulation period of CIII and CII, but CI was not affected by gas washing. This complex accumulation process leads to the hydrocarbon enrichment differences in the TZ1–TZ4 well block.

Improved understanding of mixed oil in Nigeria based on pyrolysis of asphaltenes

Crude oil from reservoirs in the onshore Niger Delta is a mixture of low and high maturity charge. Aromatic biomarkers in these oils, such as alkylphenanthrenes and alkylnaphthalenes, show relatively high thermal maturity, whereas the saturated sterane and hopane biomarkers indicate lower maturity close to the peak of the oil window. The high predicted maturity of the crude oils based on alkylphenanthrene and alkylnaphthalene indices is probably caused by mixing of high maturity condensate with less mature black oil. This correlates with the gas washing phenomenon of studied Nigerian oils caused by migrating condensate stream. The results of our study indicate that asphaltenes can be used to infer the organofacies of the low maturity petroleum charge in mixed crude oils. Compositional characteristics of the asphaltene pyrolysates indicate an origin of the related oils from Type II/III or Type III source rock kerogen. The n-alkyl-chain length distributions of the asphaltene pyrolysates predict source rocks that generated high wax paraffinic–naphthenic–aromatic oils or paraffinic oils. The n-alkyl-chain length of asphaltene pyrolysates changes in proportion to oxicity and the relative input of terrigenous organic matter to the source rock.

Improved methane fermentation of chicken manure via ammonia removal by biogas recycle

This study demonstrates methane fermentation that was carried out along with ammonia striping to avoid ammonia accumulation that significantly inhibited methane production. Ammonia was successfully removed by means of recycling of biogas followed by gas washing in sulfuric acid to capture ammonia, when chicken manure was anaerobically digested for 4 days at 55 °C and at an initial pH of 8–9. By using this method, 80% of total nitrogen in chicken manure was converted to ammonia and 82% of the produced ammonia was removed. A bench scale reactor equipped with an ammonia-stripping unit for methane production from chicken manure was developed and operated in repeated batch mode. At an initial pH of 8 and at 55 °C, 195 and 157 ml g-VS −1 of methane was successfully produced from the treated chicken manure and the mixture of treated chicken manure and raw chicken manure in the ratio of 1:1, respectively. In this method, ammonia concentration was maintained at a level lower than 2 g-N kg-wet sludge −1 in the reactor.

Oil‐based gas washing—Flexible tar removal for high‐efficient production of clean heat and power as well as sustainable fuels and chemicals

AbstractThe Energy research Centre of the Netherlands (ECN) and Dahlman Industrial Group have developed a flexible tar removal process. This oil‐based gas washing process, OLGA, besides tars, also removes dust as well as contaminants like thiophenes and dioxins from the product gas of a (biomass) gasifier. At ECN, the OLGA technology is currently applied within the Substitute Natural Gas (SNG) production process based on indirect gasification. As OLGA removes tars, but not the valuable lighter hydrocarbons like methane (CH4), acetylene (C2H2), and ethylene (C2H4), it plays a crucial role in high‐efficient SNG production processes. The OLGA in the past has been demonstrated successfully upstream Fischer‐Tropsch diesel (FT) synthesis and in Combined Heat and Power (CHP) line ups as well though, where in the latter case besides the crucial tar removal it showed also to remove dioxins present in the product gas. As such, OLGA plays a crucial role in the production of clean heat and power. © 2009 American Institute of Chemical Engineers Environ Prog, 2009

ON THE NONRELATIVISTIC ORIGIN OF RED-SKEWED IRON LINES IN CATACLYSMIC VARIABLE, NEUTRON STAR, AND BLACK HOLE SOURCES

We perform the analysis of the iron Kα lines detected in three sources representing three types of accreting compact sources: cataclysmic variable (CV) GK Per, neutron star (NS) Serpens X-1, and black hole (BH) GX 339-4. We find, using data from Epic-PN Camera onboard XMM-Newton observatory, that the iron Kα emission line in GK Per has a noticeable red-skewed profile. We compare the GK Per asymmetric line with the red-skewed lines observed by XMM-Newton in Serpens X-1 and GX 339-4. The observation of the Kα emission with red-skewed features in CV GK Per cannot be related to the redshift effects of General Relativity (GR). Therefore, if the mechanism of the Kα-line formation is the same in CVs, NSs, and BHs then it is evident that the GR effects would be ruled out as a cause of red skewness of Kα line. The line reprocessing in an outflowing wind has been recently suggested as an alternative model for a broad red-shifted iron line formation. In the framework of the outflow scenario the red-skewed iron line is formed in the strong extended wind due to its illumination by the radiation emanating from the innermost part of the accreting material. The outflow is a common phenomenon for CVs, NSs, and BHs. In this paper, we demonstrate that the asymmetric shapes of the lines detected from these CV, NS, and BH sources are well described with the wind (outflow) model. Furthermore we find by analyzing Rossi X-Ray Timing Explorer(RXTE) observations that when the strong red-skewed iron line is observed in GX 339-4 the high-frequency variability is strongly suppressed. While this fact is hard to reconcile with the relativistic models, it is consistent with the outflowing gas washing out high-frequency modulations of the radiation presumably originated in the innermost part of the source.

Quantitative assessment of gas washing of oils in the Tazhong area of the Tarim Basin, Northwest China

Gas washing has been known in the Tazhong area of the Tarim Basin, but its quantitative assessment has not yet been reported. Here the influence of gas washing fractionation in the area was discussed based on the gas chromatogram data of 68 oils and the results of the mixing experiments of a black oil and a condensate. The results show that the intensity of gas washing fractionation decreased generally from northern to southern part and vertically from deep reservoirs to shallow reservoirs. The gas washing fractionation was mainly controlled by fault systems in this area, with the increase of n-alkane mass depletion positively correlated to the number and scale of faults. Gas washing fractionation appears to have affected the hydrocarbon property, and as a result the diversity of the crude oils is markedly controlled by gas washing. In addition, the occurrence of waxy oil in this area may be resulted from multiple factors including gas washing, mixed filling and migration fractionation.

A tritium diagnostic and trap for JUDITH—First results in disruption simulation experiments with neutron irradiated beryllium during cyclic electron beam testing

In the present study, the effect of disruptions on beryllium has been studied. Disruptions are simulated in the electron beam facility JUDITH by high energetic pulses of up to 250 MJ/m 2. Under these loads, the beryllium surface may roughen combined with the forming of cracks. During the experiments, a special problem arises from the fact that during the neutron irradiation beryllium transmutes to tritium. This tritium is bound in the beryllium matrix, but during the heating of the samples, the tritium may be set free and through the vacuum pump it may be released to the environment. In order to avoid and to quantify this release of tritium, a special tritium trap has been constructed. In this tritium trap the gas is pumped by means of a metal bellows pump through a catalyst tube filled with copper oxide. At a temperature of 300 °C, the tritium is oxidized to HTO. This HTO is lead through gas washing bottles filled with water. Here approximately 98% of the released tritium is caught. The temperatures in the process are controlled by thermocouples, and the tritium content is controlled by a tritium gas monitor and in addition with a liquid scintillation counter (LSC).

Phosphorus recovery from human urine

A process to recover nutrients from human urine was tested at the Institute of Environmental Engineering (ISA) of RWTH Aachen University. Before testing the recovery process the urine was stored and the decomposition processes during this period were observed. Throughout the storage the pH value and the concentration of ammonia nitrogen increased, the concentration of phosphate phosphorus decreased. These variances can be speed up by addition of urease. The recovery process is easy to handle and approx. 99% of the load of phosphate phosphorus was eliminated and transferred into the product. Analysing the product indicators for struvite could be identified. The final step of the process is the stripping of the remaining ammonia-nitrogen by air followed by a gas washing

Reducing Crude Protein in Beef Cattle Diet Reduces Ammonia Emissions from Artificial Feedyard Surfaces

Concentrated animal feeding operations are major sources of ammonia to the atmosphere. Control methods to reduce emissions include acidifying amendments, urease inhibitors, and absorbents. For beef cattle, decreasing crude protein (CP) in diets may be the most practical and cost-effective method to reduce ammonia emissions. Our objective was to quantify the effect of reducing CP in beef cattle diet on ammonia emissions. Two groups of steers were fed diets with either 11.5 or 13.0% CP and all urine and feces were collected. Manures from the two diet treatments were applied in a replicated laboratory chamber experiment, and ammonia emission was quantified using acid gas washing. In four seasonal field trials, manures from the two diet treatments were applied to two 10-m-diameter, circular, artificial feedyard surfaces, and ammonia emission was quantified using the integrated horizontal flux method. Manure from steers fed 11.5% CP diet had less urine, less urinary N, and a lesser fraction of total N in urine, compared with the 13.0% CP diet. Decreasing crude protein in beef cattle diets from 13 to 11.5% significantly decreased ammonia emission by 44% (p < 0.01) in the closed chamber laboratory experiment, and decreased mean daily ammonia flux by 30% (p = 0.10), 52% (p = 0.08), and 29% (p < 0.01) in summer, autumn, and spring field trials, respectively. No difference was observed in winter. On an annual basis, decreasing crude protein reduced daily ammonia flux by 28%. Reducing crude protein in beef cattle diets may provide the most practical and cost-effective way to reduce ammonia emissions from feedyards.