Zootechnical and economic aspects of producing biogas out of pig manure

U istraživanju je korištena gnojovka s dvije svinjogojske farme u okolici Osijeka. Na jednoj od istraživanih farmi sustav uzgoja je na rešetkastom podu (rešetka) pa je količina suhe tvari gnojovke vrlo niska zbog velike količine tehnološke vode koja se koristi za ispiranje kanala. Količina suhe tvari (ST) iznosila je 3,8% i kondicionirana je na 10% suhe tvari dodavanjem krute separirane komponente. Kod svinja držanih na dubokoj stelji (DST) s druge farme, gnoj ima znatno veći udio suhe tvari koji iznosi 19,56%. Dodavanjem vode koncentracija ST svedena je na 10%. Prosječna dinamika stvaranja bioplina iz supstrata DST iznosila je 232,75 ml/dan, a iz supstrata rešetka 105,25 ml/dan. Evidentirana je najintenzivnija proizvodnja kod supstrata iz duboke stelje u vremenskom razdoblju od 5. do 35. dana anaerobne fermentacije s prosječnom dnevnom proizvodnjom bioplina preko 472,44 ml. Kod gnojovke (rešetka) intenzitet proizvodnje bioplina je znatno slabiji, najintenzivnija proizvodnja ostvarena je u vremenskom razdoblju od 2. do 21. dana uz prosječnu dnevnu proizvodnju od 390,92 ml. Ukupno ostvarena proizvodnja bioplina iz 500 ml svinjske gnojovke s 10% ST tijekom anaerobne fermentacije u trajanju od 80 dana iznosila je 18.768 ml (DST), a ukupna ostvarena proizvodnja iz 500 ml svinjske gnojovke s 10% ST 8.415 ml (rešetka). Testiranjem proizvodnje dnevne količine plina a time i ukupne količine plina utvrđena je statistički vrlo visoko značajna razlika (Mann-Whitney; P<0,001) iz čega se može zaključiti da je sastav gnojovke sa steljom pogodniji za proizvodnju bioplina. Istraživanja pokazuju da se iz 1 m3 bioplina može se proizvesti 6,1 kWh električne energije. Na svinjogojskim farmama troši se velika količina električne i toplinske energije. Na istraživanoj farmi s rešetkastim podovima godišnje se utroši 984200 kW električne energije i 433512 m3 zemnog plina. Izgradnjom bioplinskih pogona moguće je stajnjak i gnoj pretvoriti u energiju i na taj način osigurati vlastitu energiju, te smanjiti troškove proizvodnje.Pig manure that was used in the research was obtained on two farms situated near Osijek. The first farm used grid floor system (grid floor), so the amount of manure dry matter was low due to high amount of technological waters used for rinsing the drainage canals.The amount of 3.8% dry matter (DM) was conditioned at 10% of dry matter by adding solid separated component. The second farm used deep litter system (DL) and provided significantly higher amount of dry matter, 19.56%. By adding water, DM concentration was reduced to 10%. The average dynamics of producing biogas out of deep litter (DL) substrates was 232.75 ml/day, and out of grid floor substrates it was 105.25 ml/day. The most intensive production was achieved with deep litter substrates in the period from 5th to 35th day of anaerobic fermentation, when the average daily amount of produced gas reached 472.44 ml. Pig manure from grid floor had weaker intensity of biogas production. The most intensive biogas production was achieved from 2nd to 21st day, with average daily amount of 390.92 ml. Total biogas produced out of 500 ml of pig manure with 10% DM during an 80-day anaerobic fermentation was 18.768 ml (DL), and total biogas produced out of 500 ml pig manure from grid floor with 10% DM was 8.415 ml. By testing daily amounts of biogas and total biogas produced, statistically highly significant difference were determined (p<0.001), which led to a conclusion that deep litter pig manure was more favorable for biogas production. The research has proved that it is possible to produce 6.1 kWh of electric energy out of 1 m3 of biogas. Pig farms spend great amounts of electric and heating energy. The farm with grid floors spends yearly 984200 KW of electric energy and 433512 m3 of earth gas. Building plants for biogas production within farms enables usage of manure as a source of energy, thus producing their own energy affecting resulting in lower production costs

Zootechnical and economic aspects of producing biogas out of pig manure

U istraživanju je korištena gnojovka s dvije svinjogojske farme u okolici Osijeka. Na jednoj od istraživanih farmi sustav uzgoja je na rešetkastom podu (rešetka) pa je količina suhe tvari gnojovke vrlo niska zbog velike količine tehnološke vode koja se koristi za ispiranje kanala. Količina suhe tvari (ST) iznosila je 3,8% i kondicionirana je na 10% suhe tvari dodavanjem krute separirane komponente. Kod svinja držanih na dubokoj stelji (DST) s druge farme, gnoj ima znatno veći udio suhe tvari koji iznosi 19,56%. Dodavanjem vode koncentracija ST svedena je na 10%. Prosječna dinamika stvaranja bioplina iz supstrata DST iznosila je 232,75 ml/dan, a iz supstrata rešetka 105,25 ml/dan. Evidentirana je najintenzivnija proizvodnja kod supstrata iz duboke stelje u vremenskom razdoblju od 5. do 35. dana anaerobne fermentacije s prosječnom dnevnom proizvodnjom bioplina preko 472,44 ml. Kod gnojovke (rešetka) intenzitet proizvodnje bioplina je znatno slabiji, najintenzivnija proizvodnja ostvarena je u vremenskom razdoblju od 2. do 21. dana uz prosječnu dnevnu proizvodnju od 390,92 ml. Ukupno ostvarena proizvodnja bioplina iz 500 ml svinjske gnojovke s 10% ST tijekom anaerobne fermentacije u trajanju od 80 dana iznosila je 18.768 ml (DST), a ukupna ostvarena proizvodnja iz 500 ml svinjske gnojovke s 10% ST 8.415 ml (rešetka). Testiranjem proizvodnje dnevne količine plina a time i ukupne količine plina utvrđena je statistički vrlo visoko značajna razlika (Mann-Whitney; P<0,001) iz čega se može zaključiti da je sastav gnojovke sa steljom pogodniji za proizvodnju bioplina. Istraživanja pokazuju da se iz 1 m3 bioplina može se proizvesti 6,1 kWh električne energije. Na svinjogojskim farmama troši se velika količina električne i toplinske energije. Na istraživanoj farmi s rešetkastim podovima godišnje se utroši 984200 kW električne energije i 433512 m3 zemnog plina. Izgradnjom bioplinskih pogona moguće je stajnjak i gnoj pretvoriti u energiju i na taj način osigurati vlastitu energiju, te smanjiti troškove proizvodnje.Pig manure that was used in the research was obtained on two farms situated near Osijek. The first farm used grid floor system (grid floor), so the amount of manure dry matter was low due to high amount of technological waters used for rinsing the drainage canals.The amount of 3.8% dry matter (DM) was conditioned at 10% of dry matter by adding solid separated component. The second farm used deep litter system (DL) and provided significantly higher amount of dry matter, 19.56%. By adding water, DM concentration was reduced to 10%. The average dynamics of producing biogas out of deep litter (DL) substrates was 232.75 ml/day, and out of grid floor substrates it was 105.25 ml/day. The most intensive production was achieved with deep litter substrates in the period from 5th to 35th day of anaerobic fermentation, when the average daily amount of produced gas reached 472.44 ml. Pig manure from grid floor had weaker intensity of biogas production. The most intensive biogas production was achieved from 2nd to 21st day, with average daily amount of 390.92 ml. Total biogas produced out of 500 ml of pig manure with 10% DM during an 80-day anaerobic fermentation was 18.768 ml (DL), and total biogas produced out of 500 ml pig manure from grid floor with 10% DM was 8.415 ml. By testing daily amounts of biogas and total biogas produced, statistically highly significant difference were determined (p<0.001), which led to a conclusion that deep litter pig manure was more favorable for biogas production. The research has proved that it is possible to produce 6.1 kWh of electric energy out of 1 m3 of biogas. Pig farms spend great amounts of electric and heating energy. The farm with grid floors spends yearly 984200 KW of electric energy and 433512 m3 of earth gas. Building plants for biogas production within farms enables usage of manure as a source of energy, thus producing their own energy affecting resulting in lower production costs

THE BIOGAS PRODUCTION BY CO-DIGESTION OF WHEAT SILAGE AND CATTLE MANURE

Cilj rada bio je utvrditi potencijal za proizvodnju bioplina iz pšenične silaže i goveđe gnojovke. Istraživanje je provedeno u diskontinuiranim reaktorima pri termofilnim uvjetima (>50°C) uz retencijsko trajanje od 45 dana. Kontrolnu skupinu činila je svježa goveđa gnojovka a eksperimentalnu goveđa gnojovka uz dodatak 5% pšenične silaže. Dodatkom pšenične silaže goveđoj gnojovki povećao se sadržaj suhe tvari u eksperimentalnoj skupini u prosjeku za 20% što je rezultiralo povećanom proizvodnjom bioplina. Tako je eksperimentalna skupina uzoraka dala veću količinu bioplina na kraju procesa u prosjeku za 36,8%. Udio metana u proizvedenom bioplinu iz eksperimentalne skupine uzoraka iznosio je u prosjeku 60,6%, izraženo na suhu tvar. Temeljem provedenog istraživanja može se zaključiti da pšenična silaža ima pozitivan utjecaj na proizvodnju bioplina u smislu povećanja količine proizvedenog metana. Od 153, 99 m3t-1 bioplina pšenične silaže moguće je dobiti 307,98 kWh električne energije i 338,27 kWh toplinske energije.The aim of this study was to determine biogas production potential from wheat silage and cattle manure. The experiment was conducted in discontinuous reactors at thermophilic conditions (>50°C) with retention time of 45 days. The control group was fresh cattle manure and the experimental group was fresh cattle manure with addition of 5% of wheat silage. Addition of wheat silage to cattle manure increased the total solids content (TS) on average by 20% which resulted in increased production of biogas. Thus, experimental group samples gave a higher amount of biogas at the end of the process on average for 36.8%. The methane content in the biogas produced in the experimental group of samples was on average 60.6%, expressed on a dry matter. On the basis of the conducted study we can conclude that wheat silage has a positive impact on the biogas production in terms of increasing the amount of methane produced. From 153.99 m3t-1 biogas wheat silage, 307.98 kWh of electricity and 338.27 kWh of thermal energy can be obtained

INTERACTION OF THE DRY MATTER ON CONTENTS OF BIOGAS PRODUCED FROM PIG MANURE

Korištenje svinjske gnojovke kao biomase za proizvodnju bioplina jedan je od načina za učinkovitu uporabu otpada uz minimalan utjecaj na okoliš. Prednost bioplina i biomase u odnosu na fosilna goriva je neusporedivo manje emisije štetnih plinova i otpadnih tvari. Opterećenje atmosfere ugljik dioksidom (CO2) pri korištenju biomase je zanemarivo, jer je količina emitiranog CO2 prilikom izgaranja jednaka količini apsorbiranog CO2 tijekom rasta biljaka. Materijal istraživanja je svinjska gnojovka sa farme u okolici Osijeka gdje su svinje držane na rešetkastom podu a u istraživanju koristila se standardna metoda i kvantitativni postupak. Na uzorku se ispitivao postotak suhe tvari (ST) i njegova ovisnost o količini nastalog bioplina različitog sastava. Količina (ST) je niska i teoretski se kreće se od 0,5 do 10 %. Ona je varijabilna i ovisi o pasmini, hranidbi, uvjetima držanja, tehnologiji, izgnojavanju itd. Uzorak sa niskom količinom (ST) sadržavao je veliku količinu pepela te je njegov postotak iznosio više od 50 %. Većina uzoraka s najvećim postotkom suhe tvari imala je visoki postotak (iznad 70 %) hlapljive organanske tvari (OT). Udio dušika (N) i CO2 viši je u bioplinu proizvedenom iz svinjske gnojovke s većim udjelom ST. Količina N obrnuto je proporcionalna količini metana (CH4) /r=-0,948; p<0,001/. Dokazana je visoko pozitivna korelacija između koncentracije ST i količine bioplina (r = 0,947, p<0,001). Količina bioplina ovisi o sadržaju ST s posebnim naglaskom na visoki postotak OT. Koncentracija CH4 najveća je kod skupine s najnižom proizvodnjom bioplina. Što je veći sadržaj suhe OT i udio masti u supstratu, veći je i postotak CH4.Taking advantage of pig manure as biomass for production of biogas, is one of the ways of efficient use of waste with minimum interaction with the environment. Biogas and biomass oposite on fossil fuels has less emission of harmfull gasses and wastage rate. Emissions of carbon dioxide (CO2) in biomass, as a fuels, become from burning out is almost equal with amoung of apsorpted CO2 during growth of plants. Material from investigation was pig manure from a farm near Osijek, where all the pigs were kept on latticed floor. Methods of investigation were quantitative procedure with standard methods. On pig manure was investigated percent of dry matter (DM) and her correlation on amount of biogas with different composition. Amount of (DM) is low and teoreticaly between 0,5- 10 %. Results are variable and depends on rase, nutrition, handeling conditions, technology... The sample with low (DM) had high amount of ash > 50 % mineral part and high amount of (DM) had > 70 % dry organic matter (DOM). Higher amount of (DM) represents nutritive base for microorganisms with growing faster and produce more methane (CH4). High amount of (DM) gave high percentage of nitrogen N and CO2. Amount of N was in inverse proportion to the amount of CH4 (r=-0,948; p<0,001). Highly positive correlation was determined between (DM) on special accent on (DOM) and biogas amount (r = 0,947, p<0,001). Methane concentration was the highest in the group with the lowest biogas production. Higher content the (DOM) and the share of has positive correlation with fat in pig manure and gave high percentage of CH4

INTERACTION OF THE DRY MATTER ON CONTENTS OF BIOGAS PRODUCED FROM PIG MANURE

Korištenje svinjske gnojovke kao biomase za proizvodnju bioplina jedan je od načina za učinkovitu uporabu otpada uz minimalan utjecaj na okoliš. Prednost bioplina i biomase u odnosu na fosilna goriva je neusporedivo manje emisije štetnih plinova i otpadnih tvari. Opterećenje atmosfere ugljik dioksidom (CO2) pri korištenju biomase je zanemarivo, jer je količina emitiranog CO2 prilikom izgaranja jednaka količini apsorbiranog CO2 tijekom rasta biljaka. Materijal istraživanja je svinjska gnojovka sa farme u okolici Osijeka gdje su svinje držane na rešetkastom podu a u istraživanju koristila se standardna metoda i kvantitativni postupak. Na uzorku se ispitivao postotak suhe tvari (ST) i njegova ovisnost o količini nastalog bioplina različitog sastava. Količina (ST) je niska i teoretski se kreće se od 0,5 do 10 %. Ona je varijabilna i ovisi o pasmini, hranidbi, uvjetima držanja, tehnologiji, izgnojavanju itd. Uzorak sa niskom količinom (ST) sadržavao je veliku količinu pepela te je njegov postotak iznosio više od 50 %. Većina uzoraka s najvećim postotkom suhe tvari imala je visoki postotak (iznad 70 %) hlapljive organanske tvari (OT). Udio dušika (N) i CO2 viši je u bioplinu proizvedenom iz svinjske gnojovke s većim udjelom ST. Količina N obrnuto je proporcionalna količini metana (CH4) /r=-0,948; p<0,001/. Dokazana je visoko pozitivna korelacija između koncentracije ST i količine bioplina (r = 0,947, p<0,001). Količina bioplina ovisi o sadržaju ST s posebnim naglaskom na visoki postotak OT. Koncentracija CH4 najveća je kod skupine s najnižom proizvodnjom bioplina. Što je veći sadržaj suhe OT i udio masti u supstratu, veći je i postotak CH4.Taking advantage of pig manure as biomass for production of biogas, is one of the ways of efficient use of waste with minimum interaction with the environment. Biogas and biomass oposite on fossil fuels has less emission of harmfull gasses and wastage rate. Emissions of carbon dioxide (CO2) in biomass, as a fuels, become from burning out is almost equal with amoung of apsorpted CO2 during growth of plants. Material from investigation was pig manure from a farm near Osijek, where all the pigs were kept on latticed floor. Methods of investigation were quantitative procedure with standard methods. On pig manure was investigated percent of dry matter (DM) and her correlation on amount of biogas with different composition. Amount of (DM) is low and teoreticaly between 0,5- 10 %. Results are variable and depends on rase, nutrition, handeling conditions, technology... The sample with low (DM) had high amount of ash > 50 % mineral part and high amount of (DM) had > 70 % dry organic matter (DOM). Higher amount of (DM) represents nutritive base for microorganisms with growing faster and produce more methane (CH4). High amount of (DM) gave high percentage of nitrogen N and CO2. Amount of N was in inverse proportion to the amount of CH4 (r=-0,948; p<0,001). Highly positive correlation was determined between (DM) on special accent on (DOM) and biogas amount (r = 0,947, p<0,001). Methane concentration was the highest in the group with the lowest biogas production. Higher content the (DOM) and the share of has positive correlation with fat in pig manure and gave high percentage of CH4

THE BIOGAS PRODUCTION BY CO-DIGESTION OF WHEAT SILAGE AND CATTLE MANURE

Cilj rada bio je utvrditi potencijal za proizvodnju bioplina iz pšenične silaže i goveđe gnojovke. Istraživanje je provedeno u diskontinuiranim reaktorima pri termofilnim uvjetima (>50°C) uz retencijsko trajanje od 45 dana. Kontrolnu skupinu činila je svježa goveđa gnojovka a eksperimentalnu goveđa gnojovka uz dodatak 5% pšenične silaže. Dodatkom pšenične silaže goveđoj gnojovki povećao se sadržaj suhe tvari u eksperimentalnoj skupini u prosjeku za 20% što je rezultiralo povećanom proizvodnjom bioplina. Tako je eksperimentalna skupina uzoraka dala veću količinu bioplina na kraju procesa u prosjeku za 36,8%. Udio metana u proizvedenom bioplinu iz eksperimentalne skupine uzoraka iznosio je u prosjeku 60,6%, izraženo na suhu tvar. Temeljem provedenog istraživanja može se zaključiti da pšenična silaža ima pozitivan utjecaj na proizvodnju bioplina u smislu povećanja količine proizvedenog metana. Od 153, 99 m3t-1 bioplina pšenične silaže moguće je dobiti 307,98 kWh električne energije i 338,27 kWh toplinske energije.The aim of this study was to determine biogas production potential from wheat silage and cattle manure. The experiment was conducted in discontinuous reactors at thermophilic conditions (>50°C) with retention time of 45 days. The control group was fresh cattle manure and the experimental group was fresh cattle manure with addition of 5% of wheat silage. Addition of wheat silage to cattle manure increased the total solids content (TS) on average by 20% which resulted in increased production of biogas. Thus, experimental group samples gave a higher amount of biogas at the end of the process on average for 36.8%. The methane content in the biogas produced in the experimental group of samples was on average 60.6%, expressed on a dry matter. On the basis of the conducted study we can conclude that wheat silage has a positive impact on the biogas production in terms of increasing the amount of methane produced. From 153.99 m3t-1 biogas wheat silage, 307.98 kWh of electricity and 338.27 kWh of thermal energy can be obtained