Reduction of ammonia emission by slurry acidification and methane fermentation technology Текст научной статьи по специальности «Сельское хозяйство, лесное хозяйство, рыбное хозяйство»

УДК 631.9

СОКРАЩЕНИЕ ВЫБРОСОВ АММИАКА ПУТЕМ ПОДКИСЛЕНИЯ ЖИДКОГО НАВОЗА И ПРИМЕНЕНИЯ ТЕХНОЛОГИИ МЕТАНОВОГО СБРАЖИВАНИЯ

В. РОМАНЮК, доктор наук; Я. БАРВИЦКИ, доктор наук

Институт технологий и естественных наук, Отделение в Варшаве, Польша

Университет штата Мэриленд (США) провел исследование общей концентрации аммиака в воздухе над наиболее продуктивными сельскохозяйственными регионами мира. Результаты исследования показывают её увеличение в воздухе и необходимость проведения работ в соответствии с изменением этой ситуации с использованием различных решений. Окисление жидкого навоза животных оказалось эффективным решением для сведения к минимуму выбросов ТЧНз в животноводческих помещениях, во время хранения и после внесения навоза в почву, а также для повышения его удобрительной ценности, без отрицательного воздействия на другие газообразные выбросы. Это решение широко применяется в Дании, и его эффективность с точки зрения минимизации выбросов ТЯНз подтверждена документами некоторых исследованиях. Подкисление уменьшало выбросы ЫН;, из хранящегося жидкого навоза до менее чем 10% выбросов из необработанногожидкого навоза, а выбросы ЫЬЬ из внесенного на поля жидкого навоза снижались на 67%. Технология подкисления жидкого навозаимеет много преимуществ с точки зрения удобрения почвы, а также ограничения эмиссии аммиака. Конечно, для этого требуется обеспечить принятие мер безопасности, чтобы избежать непосредственного контакта сельскохозяйственных рабочих с вреднымвоздействием кислоты. Сокращение потерь азота в сельском хозяйстве является ключевым фактором сокращения эвтрофикации Балтийского моря. Большая её часть, связанная с воздушной средой,происходит из-за выбросов аммиака, а в Балтийском регионе почти все выбросы аммиака поступают от навоза. Ежегодное отложение аммиачного азота в Балтийское море в последние годы увеличивалось,а в 2012 году было больше, чем в 1995 году. Несмотря на то, что в некоторых странах наблюдается некоторое снижение выбросов, в Плане действий ХЕЛКОМ по Балтийскому морю предусмотрено ежегодное сокращение поступления азота в Балтийское морена 118 ООО тонн, а пересмотренный Гётеборгский протокол (2012 г.) требует амбициозных сокращений выбросов аммиака во всех странах региона Балтийского моря. Подкисление жидкого навоза также положительно влияет на эффективность разделения твердого/жидкого навоза:содержание сухого вещества вышев твердой фракции, N ниже, а Р выше. Комбинированная обработка должна эффективно предотвращать газообразные выбросы, повышать удобрительную ценность жидкого навоза и снижать транспортные и энергетические затраты. Уровень рН 5,5-6,4 не является очень кислым, не более кислым, чем дождевая вода, которая имеет нормальный диапазон рН от 4,5 до 8,5. Биогазовые экспериментыпоказывают возможность использования жидкого навоза с высоким содержанием сухого вещества в производстве биогаза.

Ключевые слова: новая технология, подкисление жидкого навоза, эмиссия аммиака, охрана окружающей среды, производство биогаза.

REDUCTION OF AMMONIA EMISSION BY SLURRY ACIDIFICATION AND METHANE FERMENTATION TECHNOLOGY

Технологии и технические средства механизированного производства продукции

растениеводства и животноводства_

PROF. DRHAB. WACLAW ROMANIUK; ASSOC.PROF.DR НАБ. JAN BARWICKI Institute of Technology and Life Sciences, Warsaw Branch, Poland

University of Maryland (USA) studiedthe global ammonia concentrations in the air over the most productive agricultural regions in the world. Research results show the growing ammonia concentration in the air and the needs to provide the work to change this situation using different solutions. Acidification of animal slurry has proved to be an efficient solution to minimize NH3 emissions in-house, during storage, and after soil application, as well as to increase the fertilizer value of slurry, without negative impacts on other gaseous emissions. This solution has been commonly used in Denmark, and its efficiency with regard to the minimization of NH3 emissions has been documented in some studies. Acidification reduced NH3 emission from stored slurry to less than 10% of the emission from untreated slurry, and the NH3 emission from applied slurry on the field was reduced by 67%. Slurry acidification technology gives many advantages from the point of view of soil fertilization and also of limiting the ammonia emissions. Of course it requires to provide safety procedures to avoid direct contact of farm workers with harmful effect of the acid. Reducing the loss of nitrogen from agriculture is a key measure to abate eutrophication of the Baltic Sea. Most of the airborne eutrophication to the Baltic Sea comes from ammonia emissions, and in the Baltic Sea Region almost all ammonia emissions are from livestock manure. Annual deposition of ammonia nitrogen to the Baltic Sea has been increasing during recent years and was greater in 2012 than in 1995. While emissions are decreasing slightly in some countries, HELCOM Baltic Sea Action Plan calls for a reduction of 118,000 tonnes of nitrogen annually to the Baltic Sea, and the Revised Gothenburg Protocol (2012) calls for ambitious reductions in ammonia emissions from all Baltic Sea Region countries. Slurry acidification also positivelyaffects solid/liquid slurry separation efficiency; DM is higher, N is lower and P is higher in the solid fraction. A combined treatment should efficiently prevent gaseous emissions, increase fertilizer value of slurry and reduce transport and energy costs. pH level of 5.5- 6.4 is not very acidic; no more acidic than rain water, which has a normal pH range from 4.5 to 8.5. Biogas experiments show the possibility of utilization of slurry with high dry matter content in biogas production.

Keywords: new technology, slurry acidification technology, ammonia emission, environment protection, biogas production.

INTRODUCTION

Researchers from University of Maryland (USA) undertook the first long-term study of global ammonia concentrations in the air over the four most productive agricultural regions in the world. They used data from NASA's Atmospheric Infrared Sounder (AIRS) satellite. Their analysis shows that between 2002 and 2016, ammonia concentrations over agricultural regions in the USA, Europe, China and India continued to grow. This, in turn, translates into ever-deeper water and air quality in these areas. Despite the differences between the different areas, the main factors influencing the increase in ammonia according to researchersare the use of fertilizers, slurry matter of farm animals, changes in the composition of the atmosphere and warming of the soil, which retains less ammonia. The study was published in March 2017 in "Geophysical Research Letters" (Warner et al. 2017). Ammonia in the gaseous state is a part of the nitrogen cycle in nature, but excessive concentration harms plants and lowers water and air quality. In the lowest atmosphere, the troposphere, ammonia reacts with nitric and sulfuric acids to form nitric-containing particles, adding to the air pollution. Ammonia can also sink back into the ground and into lakes, rivers and oceans, where it contributes to the flowering of harmful algae and the formation of so-called"dead zones" with very low oxygen content. Taking into account four studied regions of the world, the smallest increase in ammonia concentrations in the air was recorded in Europe. According to the

researchers, this is partially owing to the regulations limiting the use of ammonia fertilizers and better methods of livestock waste disposal. However, the main factor was probably - as in the United States - the reduction of the so-called acid rain, which previously removed ammonia from the atmosphere. Slurry acidification can be explained as equilibrium between the water bound ammonium (NH4+) and the volatile ammonia (NH3) is moved towards ammonium by adding acid to the slurry. Normally, concentrated sulphuric acid is used, and the costs of the acid in many cases are outweighed by savings on purchase of S fertiliser. The nitrogen, whichis captured via avoided ammonia evaporation, is turned into savings on the purchase of N fertiliser, or into higher crop yields. Slurry acidification also has a considerable climate effect by increasing the carbon sequestration in soil. Reducing the loss of nitrogen from agriculture is a key measure to reduce eutrophication of the Baltic Sea. Most of the airborne eutrophication to the Baltic Sea comes from ammonia emissions, and in the BSR almost all ammonia emissions are from livestock manure. Annual deposition of ammonia nitrogen to the Baltic Sea has been increasing during recent years and was greater in 2012 than in 1995. While emissions are decreasing slightly in some countries, HELCOM Baltic Sea Action Plan calls for the reduction of 118,000 tonnes of nitrogen annually to the Baltic Sea, and the Revised Gothenburg Protocol (2012) calls for ambitious reductions in ammonia emissions from all BSR countries. Slurry acidification also affects positivelysolid/liquid slurry separation efficiency: DM is higher, N is lower and P is higher in the solid fraction. A combined treatment should efficiently prevent gaseous emissions, increase fertilizer value of slurry and reduce transport and energy costs.

INTERREG PROJECT CONCERNING SLURRY ACIDIFICATION TECHNOLOGY

Technical report concerning the feasibility studies for pilot installations of Interregslurry scidificationtechnologies (SAT) activity was provided by Institute of Technology and Life Sciences (ITP) in Falenty, Branch in Warsaw. In the application formthe "in storage" system was planned to be utilized in Polish conditions. All Baltic countries: Sweden, Denmark, Finland, Germany, Poland, Estonia, Lithuania and Latvia are involved in the project. Russia and Belarus are also involved as cooperating members of the project. ITP has three experimental farms located ata distance of about 300 km one from another. In each of thefarms there are barns with approximately 180 cows oneach site. The experimental farm in Falenty has a chemical laboratory, which can provide sample tests taken from acidification experiments. In this situation, it was decided to have two concrete tanks of approximately 12.5 m3 each to provide two different experiments - slurry acidification research and concrete tests concerning influence of harmful substances on the construction material itself. Acidification of animal slurry has proved to be an efficient solution to minimize NH3emissions in-house, during storage, and after soil application, as well as to increase the fertilizer value of slurry, without negative impacts on other gaseous emissions.

Figure 1 shows two concrete tanks staying side by side; one is for fresh slurry and the other-for acidified slurry. These tanks are equipped with one mixer and one pump, which can be moved very easy from one tank to the other depending on the requirements. Fresh slurry from the right tank is pumped to the left tank, where acidification occurs. Acidification process is controlled by pH meter. When the process is completed,a tanker using a discharge pipe RB takes the acidified slurry.

Source: Interreg 2017 Figure 1: Experimental pumping of fresh slurry to acidification tank

Рис. 1. Экспериментальное перекачивание свежего жидкого навоза в емкость для

подкисления:

ITC - dosing pump with рН meter - насос-дозатор с измерителемрН ZzSK - container with acid - контейнер с кислотой М - mixer - мешалка PMiP - pump - насос ZT - three way valve - тройниковый клапан ZGprzZ - tank with fresh slurry - емкость со свежим жидким навозом ZGpoZ - tank with acidified slurry - емкость с подкисленным навозом RB - discharge pipe - выходная труба

Analysis of different storage tanks and acidification systems was provided. In addition, economic analysis concerning possible usage of acidified slurry on different crops such as corn, wheat, grass, etc.,was done. Costs of such energy as electricity, gas, petrol, etc.,were taken into consideration. Technical documentation of two concrete tanks waselaborated. To provide acidification process in these two tanks special automated system was elaborated. The main elements of that system are pump, mixer, pH meter, and temperature meter. When slurry achievesthe required pH value, it is pumped to the tanker with trailing hoses, which will spread the acidified slurry on the field plots for further experiments. After analysis of different "in storage" systems present on the Danish market, one of the systems was chosen, which can be suitable for the Polish animal herd sizes and possibility of safe acid delivery on the farm, where acidification process will take place. This system contains the following main elements: main frame with power transmission taken from PTO of the tractor, slurry mixer, acid pump, which delivers acid from the truck with acid to the area of slurry mixer activity, pH meter, which can check when required pH level of slurry is achieved.

BIOGAS EXPERIMENT CONCERNING SLURRY FERMENTATION WITH HIGH DRY MATTER CONTENT

Figure 2 shows a schematic diagram of the device, which allows to examine the individual elements of the technological process of fermentation and allows to conduct substrate fermentation studies, to determine their physical and chemical characteristics, and further determine the characteristics of the fermentation process, the quality and quantity of obtained biogas and quality of digestive residues. This sequence of work can help to design the station for biogas production,

mainly from the substrate in the form of mixture of manure, organic waste and vegetable matter. The test bed according to Figure 2 has a substrate fermentation vessel 1, communicating with the pre-fermentation tank 2 and the final fermentation tank 3.These three tanks are equipped with an insulating protective layer 5 heated by heating mantle 4. The biogas produced in these tanks is transported via lines 2 to biogas tank 24 and then to the cogeneration unit 30. During transportation to the reservoir 24, the biogas is subjected to dehydration in the trap 25 and desulphurization in the desulphurizer 26.

Figure 2: Scheme of a stand for biogas recovery from substrates with up to 12% of dry matter

content

Рис. 2. Схема установки для производства биогаза из субстратов с содержанием сухого

1 - substrate flushing tank; 2 - pre-fermented tank for rinsed organic matter; 3 - tank for final organic matter fermentation; 4 - overflow tank; 5 - external thermal insulation; 6 - tank cover; 7 -biogas feeding pipe; 8 - drain hose for rinsed organic matter; 9 - shut-off valve; 10 - tank cover; 11 -

tank cover; 12 - pump; 13 - mixing pump; 14 - siphon funnel; 15 - suction-discharge pump; 16 -drain-mixing pipeline; 17 - drain-mixing pipeline; 18 - tank cover; 19 - mixing pump; 20 - bath; 21 - drain pipe; 22 - liquid organic drainage valves; 23 - biogas discharge line; 24 - biogas tank; 25 -biogas trap; 26 - biogas desulphurization; 27 - flame breaker; 28 - biogas counter; 29 - thermometer set; 30 - cogeneration unit; 31 - safety valves; 32 - biogas pressure indicators; 33 - thermometer set; 34 - biogas sampling valves; 35 - openwork basket for solid substrate; 36 - transport pipeline for rinsed organic matter; 38 - sampling slots from chambers; 39 - filler insert; 40 - liquid level

indicator (Romaniuk et al., 2013) 1 -резервуар для промывки субстрата; 2 -резервуар предварительной ферментации промытого органического материала; 3 - резервуар для окончательной ферментации органического материала; 4 -резервуар для слива лишней жидкости; 5 -внешняя теплоизоляция; 6 -крышка резервуара; 7 -подводящий биогаз трубопровод; 8 -дренажная

труба для промытого органического материала; 9 -запорный клапан; 10 -крышка резервуара;

11 -крышка резервуара; 12 - насос; 13 -насос-смеситель; 14 -сифон-воронка; 15 -всасывающий и сливной насос; 16 - дренажно-смесительный трубопровод; 17 - дренажно-смесительный трубопровод; 18 - крышка резервуара; 19 -насос-смеситель; 20 - ванна; 21 -сливная труба; 22 -клапаны для слива жидкого органического материала; 23 -линия выпуска биогаза; 24 -емкость для биогаза; 25 -ловушка для биогаза; 26 - сероочистка биогаза; 27 -пламегаситель; 28 -счетчик биогаза; 29 -набор термометров; 30 -блок ко генерации; 31 -предохранительные клапаны; 32 -указатели давления биогаза; 33 -набор термометров; 34 -клапаны отбора проб биогаза; 35 -сетчатая корзина для твердого субстрата; 36 -трубопровод для транспортировки промытого органического материала; 3 8 -отверстия для отбора проб из камер; 39 -наполнительная вставка; 40 -индикатор уровня жидкocти(Romanшk et al., 2013).

TEST RESULTS CONCERNING FERMENTATION PROCESS USING SLURRY WITH HIGH DRY MATTER CONTENT

Average evaluation of process parameters of fermentation mixtures tested on substrates with dry matter content equal to 10%are presented in Table 1.

Table 1

Average evaluation of process parameters of fermentation mixtures tested on substrates with dry

matter content equal to 10% (Myczko et al., 2015)

параметры ферментационной смеси Process parameters of fermentation OS ZPE 15/15 sample 10% PC (OS WD) ZPE 15/15 sample 10% ST (OS WD) ZPE 15/15 sample 10% OP ZPE 15/15 sample 10% PC (OP WD) ZPE 15/15 sample 10% ST (OP WD) ZPE 15/15 sample 10% OP ZPE 15/15 sample 10% PC (OP WD) ZPE 15/15 sample 10% ST (OP WD) ZPE 15/15 sample 10% K0 - inoculum

PH-H2O inital исходные TEMP. KOMPENSTIO Nin lab. temp.:20.5oC 7.28 ±0.07 28.2°C 7.32 ±0.07 26.ГС 7.31 ±0.07 26.9°C 7.16 ±0.07 25.6°C 7.20 ±0.07 27.8°C 7.20 ±0.07 25.1°C 6.94 ±0.07 24.6° C 6.95 ±0.08 26.8°C 6.94 ±0.07 26.1° C 7.02 ±0.07 31,1°C

Растворенный кислород Dissolved oxygen O9* 0.02 [mg/l] 0.06 [mg/l] 0.11 [mg/l] 0.02 [mg/l] 0.09 [mg/l] 0.13 [mg/l] 0.02 [mg/l] 0.08 [mg/l] 0.02 [mg/l]

Щелочной буферный потенциал Alkaline buffer potentialLKT/OWN * 4.16 4.68 2.94 4.31 4.53 3.12 4.33 4.14 2.06 0.08

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Content

Содержание

CH4

53.6%

46.8%

51.3%

55.1%

48.8%

50.5%

50.7

%

43.6%

50.3

%

NH3

23.6 ppm

12.3pp m

20.2%

18.4 ppm

18.5pp m

12.2pp m

8.7 ppm

4.7 ppm

4.0 ppm

2.56 PPm

H2S

128 ppm

113pp m

22ppm

216 ppm

125 ppm

24 ppm

34 ppm

30 ppm

22 ppm

9 ppm

4

4

4

* Results of dissolved oxygen and alkaline buffer potential were obtained by the

method beyond the scope of accreditation Результаты по растворенному кислороду и щелочному буферному потенциалу

были получены методом, выходящим за рамки аккредитации

** The result of the biogas yield is the net amount of gas from the test sample; the result of biogas yield from the inoculum is given for orientation

Технологии и технические средства механизированного производства продукции растениеводства и животноводства

Результат по выходу биогаза - это чистый объем газа из тестируемого образца; результат выхода биогаза из ииокулята приведен для ознакомления

Control test K0 - Inoculate methane fermentation bacteria. Lab conditions: temp 21.6-22.5oC, moisture. 38.9-41.6%, pressure: 1007.0-1013.0 hPa; Total drying time: 60 hours, total roasting time: 10 hours

INFLUENCE OF ACIDIFICATION ON CONCRETE SLURRY TANKS

To study the effect of the influence of acidic slurry on concrete the standard concrete samples with the dimensions15x15x15 cm, made from two grades of concrete C25/30 and 30/37 in an amount of 66 pieces were used. Aggressive slurry acidified to pH of 5.5. was taken as medium. All samples were manufactured by the company Hydrobudowa and had undergone a process of care and maturation for 28 days under conditions specified in the standard. Then samples were placed in an acidified slurry, normal slurry and water. Storage time of samples in different media was set at 6 months, 12 months and 18 months. The samples will undergo the strength tests of concrete and selective microscopic examination of SEM. Three samples will pass the endurance test, of which the average value is calculated. The reference point is obtained from compressive strength of concrete samples after 28 days of maturation and comparison with the results of strength tests and microscopic studies conducted on the samples stored in various media for different time periods. For laboratory tests concerning the effect of acidic slurry on reinforcing steel, the samples of concrete with embedded reinforcement were prepared in the laboratory Hydrobudowa. In the samples with the dimensions of 4x4x16 cm in the amount of 33 pieces a rod of 6 mm diameter is placed, protected by a concrete layer 2mm, 7mm and 17mm thick. Samples were placed in the following media: acidified slurry, normal slurry and water. The samples will be kept for 6 months, 12 months and 18 months. The measure of corrosive action of acidic slurry will be the toughness of the samples on strength when bending. The survey will be carried out on a strength-testing machine. Samples will be also a subject of macroscopic evaluation. The reference point is reached by breaking strength of concrete samples after 28 days of maturation and macroscopic evaluation of steel reinforcement. The results will be compared with results from research samples stored in different media for different periods.

Acidification of slurry is spontaneously changed, that is why monitoring of the level of acidity of pH and temperature was introduced.

FARM TRIALS USING PROFESSIONAL EQUIPMENT FROM DENMARK

Mobile acidification equipment could be suitable for acidifying the slurry in storage during mixing just before spreading. The farmer could invest into such equipment. Mobile equipment implies that the cost can be shared if the same equipment is used on several farms. The service could also be hired from a contractor, under the conditions that there is a contractor in the neighborhood providing this service.

Figures 3 shows the equipment, which will be delivered by ORUM Co. from Denmark.

This professional equipment can have a big influence on the interest of farmers with large herd size of animals in Poland.

Figure 3: OrumSemden's"in storage" acidification system at work (farm in Denmark) Source: ORUM Co promotion material, 2017 Рис. 3. Система иодкисления в хранилище OrumSemden в рабочих условиях (хозяйство в

Дании)

Why ammonia evaporation does not exist,can be explained by drawing the following equilibrium in slurry between ammonium salt and ammonia gas

NH4+ + OH <-> NH3 +H20 At pH=6.4 all mineralized N is found as ammonium, and no evaporation takes place. In Denmark, the slurry after lowering pH <6should be spread within 24 hours according to the rules. As the spreading season lasts longer, this could mean a period of several weeks per year. Economical calculations are needed to compare, which solution is most profitable for individual farms. When hiring the acidification service, the technology will be available also for smaller farms. Also, if the surplus storage volume is needed because of foaming when adding acid, the alternative may become non-profitable compared to other two alternatives. Description of processes when adding the sulphuric acidto slurry is presented below:

NH3(ammonia) + H+= NH4+(ammonium)

NH3= gas -may evaporate NH4+= salt -does not evaporate)

H2SO4 (Sulphur acid) = Hydrogen - Sulphur-Oxygen = Sustainable

The concept of reducing slurry pH to get lower nitrogen losses to the air relies on the equilibrium between NH4and NH3,thatis presented on Figure 4.

Source: David Fangueiro 2015 Figure 4: Effect of slurry pH on its relative content of NH4+(A) and H2S (B). Рис. 4. Влияние pH жидкого навоза на относительное содержание NH4+(A) и H2S (В).

CONCLUSIONS

pH level of 5.5- 6.4 is not very acidic, and no more acidic than rain water, which has a normal pH range from 4.5 to 8.5.

Acidification reduces NH3 emission from pig houses by 70% compared with the standard housing treatment. Little loss was observed from the stored slurry, and NH3 emission from applied slurry was reduced by 67%. In consequence, 43% (S.E. 27%) increase in mineral fertilizer equivalent (MFE) was measured in field studies. The slurry acidification system is an approved Best Available Technology (BAT) in Denmark.

Slurry acidification technology gives many advantages from the point of view of soil fertilization and the limiting of ammonia emission. Of course, it requires safety procedures to avoid direct contact of farm workers with harmful effect of the acid. However, having good acidification technology, which does not allow having direct contact with the acideither in the storage area or in the field, this job is rather safe while fulfilling the procedures.

Acidification of animal slurry has proved to be an efficient solution to minimize NH3 emissions in-house, during storage, and after soil application, as well as to increase the fertilizer value of slurry, without negative impacts on other gaseous emissions.

Besides, acidification has a positive effect on other slurry treatments such as solid liquid separation or composting; upon the use of a non-sulfur containing additive, it may also

affectpositively the biogas production. Nevertheless, acidification of slurry might induce higher losses by leaching, due to solubilisation of mineral elements.

REFERENCES

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5. Fangueiro, D., Surgy, S., Coutinho, J., Vasconcelos, E., 2013.Impact of cattle slurry

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Geophysical

-2884 DOI: 10.1002/2016GL072305