Solid compost from biogas plant digestion residues - a new product

Here is presented the nitrogen content of dairy cattle solid manure treated anaerobically and aerobically

Dry anaerobic digestion of organic residues on-farm - a feasibility study

Objectives The feasibility study shall answer the following questions: Are there economical and ecological advantages of on-farm dry digestion biogas plants? How the construction and operation parameters of a dry digestion biogas plant influence environment, profit, and sustainability of on-farm biogas production? The aim of the feasibility study is to provide facts and figures for decision makers in Finland to support the development of the economically and environmentally most promising biogas technology on-farm. The results may encourage on-farm biogas plant manufacturers to develop and market dry anaerobic digestion technology as a complementary technology. This technology may be a competitive alternative for farms using a dry manure chain or even for stockless farms. Results Up to now farm scale dry digestion technology does not offer competitive advantages in biogas production compared to slurry based technology as far as only energy production is concerned. However, the results give an over-view of existing technical solutions of farm-scale dry digestion plants. The results also show that the ideal technical solution is not invented yet. This may be a challenge for farmers and entrepreneurs interested in planning and developing future dry digestion biogas plants on-farm. Development of new dry digestion prototype plants requires appropriate compensation for environmental benefits like closed energy and nutrient circles to improve the economy of biogas production. The prototype in Järna meets the objectives of the project since beside energy a new compost product from the solid fraction was generated. On the other hand the two-phase process consumes much energy and the investment costs are high (>2000 € m-3 reactor volume). Dry digestion on-farm offers the following advantages: Good process stability and reliability, no problems like foam or sedimentation, cheap modules for batch reactors, less reactor capacity, reduced transport costs due to reduced mass transfer in respect of the produced biogas quantity per mass unit, compost of solid digestion residues suitable as fertiliser also outside the farm gate, use of on-farm available technology for filling and discharging the reactor, less process energy for heating because of reduced reactor size, no process energy for stirring, reduced odour emissions, reduced nutrient run off during storage and distribution of residues because there is no liquid mass transfer, suitable for farms using deep litter systems. These advantages are compensated by following constraints: Up to 50% of digestion residues are needed as inoculation material (cattle manure does not need inoculation) requiring more reactor capacity and mixing facilities. Retention time of dry digestion is up to three times longer compared to wet digestion requiring more reactor capacity and more process energy, filling and discharging batch reactors is time and energy consuming. We conclude that only farm specific conditions may be in favour for dry digestion technology. Generally, four factors decide about the economy of biogas production on-farm: Income from waste disposal services, compensation for reduction of greenhouse gas emission, compensation for energy production and - most important for sustainable agriculture - nutrient recycling benefits. Evaluation of the results We did not find any refereed scientific paper that includes a documentation of an on-farm dry digestion biogas plant. It seems that we tried first. We also could not find any results about the biogas potential of oat husks, so we may have found these results first. Farm scale production of anaerobically treated solid manure for composting is new. Dry fermentation biogas plants offer the possibility to design solid manure compost by variation of fermentation process parameters. From different scientific publication databases we found about 10 000 references concerning biogas research during the past 10 years. Less than ten are dealing with biogas reactors for non-liquid substrates on-farm. Recent research mainly concentrates on basic research, biogas process research for communal waste, large-scale biogas plants, and research on laboratory level. This mirrors the fact, that production of research papers is rather financed than product development on site. Our conclusion is that it seems worldwide to be very difficult or even impossible to find financial support for on site research, especially for on-farm prototype biogas reactors. We suppose the following reasons for this fact: biogas plant research requires proficiency in many different scientific disciplines, lack of co-operation between engineering and life sciences, high development costs to transfer basic research results into practical technical solutions, low interest of researchers because on site and on-farm research enjoys low appreciation in terms of scientific credits, portability of farm specific design and process solutions is difficult. Our conclusion is that on site and on-farm research has to be supported by funding agencies if integration of biogas and bio energy into the farm organism is considered as an important target within the agricultural policy framework. Future research on both dry fermentation technique and biogas yield of solid organic residues may close present knowledge gaps. Prototype research may offer competitive alternatives to wet fermentation for farms using a solid manure chain and/or energy crops for biogas production. To encourage farmers and entrepreneurs to foster the development of dry fermentation technology support in terms of education and advisory services is also necessary

Kuivamädätys tuottaa lämpöä ja lannoitetta

Lietelantaa voidaan helposti mädättää biokaasuksi. Nyt myös kuivalannasta pystytään tuottamaan biokaasua karja-, hevos-, turkis- ja siipikarjatiloilla. Tämän mahdollistaa uusimmalla kuivamädätystekniikalla toimiva biokaasulaitos.vo

Hyviä käytäntöjä tuorekasviksia pilkkoville yrityksille

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Nutrient balance of a two-phase solid manure biogas plant

So called "dry fermentation" prototype plants for anaerobic digestion of organic material containing 15-50 % total solids show added advantages compared to slurry digestion plants (Hoffman 2001): Less reactor volume, less process energy, less transport capacity, less odour emissions. However on-farm dry fermentation plants are not common and rarely commercially available. Recent on-farm research (Kusch & Oechsner 2004) and prototype research (Linke 2004) show promising technical solutions for dry fermentation batch reactors on-farm. The Biodynamic Research Institute in Järna developed a two-phase on-farm biogas plant. The plant digests manure of dairy cattle and organic residues originating from the farm and the surrounding food processing units containing 17.7-19.6 % total solids. A new technology for continuously filling and discharging the hydrolysis reactor was developed and implemented. The output of the hydrolysis reactor is separated into a solid and liquid fraction. The solid fraction is composted. The liquid fraction is further digested in a methane reactor and the effluent used as liquid fertiliser. Initial results show that anaerobic digestion followed by aerobic composting of the solid fraction improves the nutrient balance of the farm compared to mere aerobic composting. Composted solid fraction and effluent together contain about 70 % of total input nitrogen and 94 % of input NH4. The manure that was merely aerobic digested contained about 51 % of total input nitrogen and 3.9 % of input NH4. Additionally anaerobic digestion improves the energy balance of the farm producing up to 269 l biogas kg-1 volatile solids or 1,7 kWh heat kg-1 volatile solids

Improving quality and treatment of water and vegetables in fresh-cut vegetable processing

Fresh-cut vegetables have been cleaned, peeled, chopped, sliced, or diced and then packaged but not heated. The fresh-cut vegetable processing industry uses large volumes of water. This water is utilized by hygiene and cleaning processes and for cooling of the products. Knowledge has been lacking about waters created and the water use in different stages of the fresh-cut vegetable processing. Obtaining information about the water use and waste water production is important for recocnizing critical phases for risk management and for evaluating the need of water treatments. The aim of this study was to improve the processing of fresh-cut vegetables through collecting information on the hygienic level of waters and vegetables, decontamination methods and their efficacy, water use and waste waters which helps companies to improve their processes and self-monitoring activities. One aim of this study was to also evaluate on-farm waste water treatment systems carrying out peeling of vegetables. Water consumption, measured in six fresh-cut processing companies in this study, was 2.0–6.5 m3/t per finished product. The water consumption varied in the same company between months and according to season, volumes of vegetables processed, and the quality of raw material. Through regular measurement of water consumption, it is possible to decrease water use in fresh-cut vegetable processing. In the present study, water consumption decreased by 15% over the course of the three-year period examined. This may decrease costs and improve sustainability of the production. Vegetables contain 90‒96% water; the remainder is composed of components such as carbohydrates, proteins and nutrients. In vegetal cells, water is present in different forms; part of this water can easily be removed and a part cannot. Depending on their size, the substances of which vegetables are composed form different kinds of solutions in combination with water. Most of the organic load and nutrients of the vegetables processed were released into water from the peeling of root vegetables, whereas the volume of the water came primarily from the rinsing and washing of vegetables. Washing is an important step in fresh-cut vegetable processing; it removes soil and debris, and reduces microbial populations residing on the vegetable surface. Washing is often the only step that can remove foreign material and tissue exudates, as well as inactivate pathogens. Water plays a dual role in the fresh-cut vegetable processing: it both reduces and transmits microorganisms to vegetables. The high quality of water used in processing is important, and can be attained through water decontamination or by using new potable water that is changed continuously during the process. The high operational cost of water use has resulted in the industry-wide common practice of the reuse or recirculation of process water. Fresh-cut vegetables may be contaminated by pathogens in different stages and different ways after harvest. Pathogenic microorganisms can cause severe outbreaks of foodborne disease. The microbiological quality of vegetables changes during processing. The total microbial counts in peeled and cut carrots were lower than in whole washed carrots, but higher in grated than in cut carrots. The total microbial count was lower in process water than in wash water of carrots. Pathogenic Yersinia enterocolitica was detected in many carrot and water samples by sensitive RT-PCR, but not by the cultivation method. The data concerning treatment of process water of fresh-cut wagetable processing is quite scarce, in particular concerning the effect of treatments on yersinia. Water decontamination methods neutral electrolyzed water (NEW), chlorine dioxide (ClO2), organic acids and UV-C was evaluated, specially on yersinia, E. coli and Candida lambica (yeast) in this study. The effect of decontamination on different microbes in water differs with, e.g., time, concentration, decontamination method, and turbidity of water. Technically- and economically effective chlorine-alternative decontamination technologies are the goal of the fresh-cut industry. In Finland, and in many other EU countries as well, chemical treatments of vegetable process waters are restricted in food legislation, but allowed in other countries. Published information concerning the functioning and feasibility of small on-farm waste water treatment plants are few. Waste water generated from vegetable production contains high concentrations of biochemical oxygen demand (BOD) and suspended solids (SS). One aim of this study was to evaluate on-farm waste water treatment systems carrying out peeling of vegetables. Primary treatments of waste water remove coarse solids, reduce organic matter content and adjust pH. Secondary, biological, wastewater treatment removes soluble organic matter and nutrients from water. Biological waste water treatment, such as a sequencing batch reactor or a trickling filter, are used for treating of vegetable processing waste water in small scale companies in rural areas. In the case of both systems, the requirements set in legislation were met. Tertiary treatment can be used if waste water is reused in subsequent vegetable processing or recycled for irrigation of food crops. Fresh-cut vegetable processing companies produce high-quality fresh-cut produce with appropriate inputs and processes. Each company must establish its own specific validation protocols for evaluating their processes. The aim is to minimize the risks and produce healthy, safe, fresh and easy-to-use vegetables for consumers.Tuorekasvikset on puhdistettu, kuorittu, pilkottu (viipaloitu, silputtu tai kuutioitu) ja pakattu, mutta niitä ei kuumenneta missään prosessin vaiheessa. Tuorekasvisten prosessoinnissa käytetään paljon vettä; sitä tarvitaan raaka-aineiden, tuotteiden ja tilojen puhdistuksessa sekä hygienisoinnissa. On vain vähän tutkittua tietoa siitä, missä tuorekasvisten prosessoinnin vaiheissa ja miten paljon vettä käytetään ja miten paljon jätevesiä muodostuu. Tutkimustieto yritysten veden käytöstä ja jätevesien muodostumisesta on tärkeää, jotta voidaan tunnistaa riskien hallinnan kannalta kriittiset prosessien vaiheet ja arvioida jätevesien käsittelytarvetta. Tämän tutkimuksen tavoitteena oli kehittää tuorekasvisten prosessointia keräämällä tietoa vesien ja kasvisten hygieenisestä laadusta, vesien hygienisointimenetelmistä ja niiden tehokkuudesta, veden käytöstä sekä jätevesistä. Tavoitteena oli myös arvioida tilakohtaisia kasvisten prosessoinnin jätevesien käsittelymenetelmiä. Tämä tieto auttaa yrityksiä kehittämään prosessejaan ja tehostamaan omavalvontaansa. Veden määrä, jota mitattiin tässä tutkimuksessa kuudessa tuorekasviksia prosessoivassa yrityksessä, vaihteli eri yrityksissä välillä 2,0–6,5 m3 lopputuotetonnia kohden. Veden käyttö vaihteli myös tietyssä yrityksessä eri kuukausina riippuen käsiteltävien kasvisten määristä, raaka-aineen laadusta ja vuodenajasta. Yrityksissä, joissa seurattiin säännöllisesti veden käyttöä, saatiin veden kulutusta pienennettyä. Tässä tutkimuksessa veden kulutus laski yhdessä yrityksessä 15 % kolmen vuoden seurantajakson aikana. Säästämällä vettä voidaan pienentää kustannuksia ja parantaa tuorekasvisten prosessoinnin kestävyyttä. Kasvikset sisältävät vettä 90–96 % painostaan; loppuosa koostuu muun muassa hiilihydraateista, proteiineista ja muista ravintoaineista. Suurin osa kasvisten prosessoinnissa jäteveteen päätyvästä orgaanisesta aineesta (BOD, biological oxygen demand) ja ravinteista siirtyi tutkimuksen mukaan veteen juuresten kuorintavaiheessa, kun taas pääosa veden kulutuksesta tapahtui kasvisten pesussa ja huuhtelussa. Kasvisten pesu on tärkeä vaihe tuorekasvisten prosessoinnissa; siinä kasviksista poistuu maa-ainesta ja kasvisten pintakerrosta ja se vähentää mikro-organismien määrää kasvisten pinnalla. Pesu on usein ainoa vaihe, jolla voidaan poistaa epäpuhtauksia ja muuta vierasta materiaalia kasviksista. Vedellä on kuitenkin kaksitahoinen rooli tuorekasvisten prosessoinnissa: mikro-organismien vähentämisen lisäksi vesi voi myös levittää niitä kasviksiin. Tuorekasvisten prosessoinnissa käytettävän veden laadun täytyy olla hyvää, ja laadun hallinnassa voidaan käyttää hyväksi erilaisia veden puhdistusmenetelmiä tai vettä voidaan vaihtaa jatkuvasti prosessin aikana. Veden korkean käyttökustannuksen vuoksi yritykset pyrkivät kierrättämään tai käyttämään vettä uudelleen. Kasvisten mikrobiologinen laatu muuttuu prosessoinnin aikana. Tautia aiheuttavat mikro-organismit voivat saastuttaa kasviksia prosessin eri vaiheissa ja aiheuttaa ruokamyrkytyksiä. Tässä tutkimuksessa kokonaismikrobien määrä kuorituissa ja pilkotuissa porkkanoissa oli alhaisempi kuin kokonaisissa, pestyissä porkkanoissa, mutta määrä oli korkeampi porkkanaraasteessa kuin pilkotuissa porkkanoissa. Kokonaismikrobien määrä oli alhaisempi porkkanoiden prosessi- kuin pesuvedessä. Patogeenista Yersinia enterocolitica-bakteeria löydettiin monista porkkana- ja vesinäytteistä kun käytettiin herkkää PCR-menetelmää, mutta bakteeriviljelymenetelmällä niitä ei havaittu. Aiempia mittaustuloksia tuorekasvisten prosessivesistä on melko vähän saatavissa, varsinkin yersiniaan liittyen. Tässä työssä vertailtiin veden puhdistusmenetelmiä, kuten neutraalia elektrolysoitua vettä (NEW), klooridioksidia (ClO2), orgaanisia happoja ja ultraviolettivaloa (UV-C), ja arvioitiin menetelmien tehoa yersinia- ja E. coli -bakteereihin sekä Candida lambica -hiivaan. Puhdistuksen tehokkuuteen vaikuttaa näissä vesissä erityisesti veden sameus. Tuorekasvisten prosessoinnissa tavoitteena on löytää teknisesti ja taloudellisesti tehokas veden puhdistusmenetelmä, jossa ei käytetä klooria. Suomessa ja monessa muussa EU-maassa kemiallista käsittelyä, esimerkiksi kloorin käyttöä, kasvisten prosessoinnissa on rajoitettu elintarvikelainsäädännössä, mutta klooria käytetään monissa muissa maissa. Pienen kokoluokan yrityskohtaisesta jätevedenkäsittelystä on olemassa vähän julkaistua tietoa. Kasvisten prosessoinnissa muodostuva jätevesi sisältää paljon orgaanista ainetta sekä kiintoainetta. Jäteveden esikäsittelyllä voidaan muun muassa vähentää veden kiintoaineen ja orgaanisen aineen pitoisuuksia sekä säätää happamuutta. Biologista jäteveden käsittelyä, kuten panospuhdistamoa tai biosuodinta, voidaan käyttää kasvisten prosessoinnissa muodostuvien jätevesien käsittelyssä viemäriverkostojen ulkopuolisilla alueilla. Tässä tutkimuksessa molemmilla menetelmillä (panospuhdistamo ja biosuodin) saavutettiin lainsäädännön vaatimukset. Jäteveden puhdistusta ja hygienisointia tarvitaan jäteveden käsittelyn jälkeen, jos jätevettä käytetään uudelleen kasvisten käsittelyprosessissa tai kasteluvetenä kasvintuotannossa. Tuorekasviksia prosessoivien yritysten tavoitteena on tuottaa korkealaatuisia tuotteita yrityksen kokoluokkaan ja resursseihin suhteutetuilla panostuksilla ja prosesseilla. Yritykset laativat oman, yrityskohtaisen omavalvontaohjeistuksensa, jolla he arvioivat prosessejaan ja koko tuotantoketjuaan. Tavoitteena on pienentää riskejä ja tuottaa terveellisiä, turvallisia ja helppokäyttöisiä kasviksia kuluttajille

Two phase continuous digestion of solid manure on-farm: design, mass and nutrient balance

During the last decade some so called ‘dry fermentation’ prototype plants were developed for anaerobic digestion of organic material containing 15-50 % total solids. These plants show added advantages com-pared to slurry digestion plants: Less reactor volume, less process energy, less transport capacity, less odour emissions. However on-farm dry fermentation plants are not common and rarely commercially available. This paper reports about an innovative two phase prototype biogas plant designed for continuous digestion of solid dairy cattle manure

Tuorevihannesten tuotantotilojen pintahygienian selvittäminen

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