WO2011151511A2

WO2011151511A2 - A method of processing organic side flows and waste slurries and a fertilizer

Info

Publication number: WO2011151511A2
Application number: PCT/FI2011/050491
Authority: WO
Inventors: Samppa Ahtiainen; Eija HÄMÄLÄINEN; Jari Järvinen
Original assignee: Cursor Oy; Stora Enso Oyj
Priority date: 2010-05-31
Filing date: 2011-05-27
Publication date: 2011-12-08
Also published as: FI20105612L; FI20105612A7; FI20105612A0; WO2011151511A3

Abstract

The present invention is directed to a method of processing organic side flows and waste slurries and a fertilizer. The method of the invention utilizes various agricultural, industrial and community waste and side flows and algae in the production of at least ethanol, biogas and fertilizer.

Description

A method of processing organic side flows and waste slurries and a fertilizer

[001 ] The present invention relates to a method of processing organic side flows and waste slurries in the manner described in the preamble of claim 1 and a fertilizer described in the preamble of claim 16. Especially preferably, a method of a preferred embodiment of the invention is related to utilizing various agricultural, industrial and community waste and side flows. In accordance with a preferred specific embodiment of the present invention the method is applicable in connection with a pulp or paper mill due to considerable synergy between the pulp and/or paper mill processes and the method of the invention.

[002] Prior art knows several processes where an individual waste or side flow is sought to be utilized either by recovering therefrom a substance for some specific purpose or by, for example, incinerating the waste or side flow in question to produce energy. The term 'side flow' is understood in this specification as such a material flow from, for instance, an industrial facility that the industrial facility cannot any more use in its own processes but that the facility may sell forward to be utilized by another user.

[003] In other words, known solutions include, among others, separating glass and metal from municipal waste for reuse as well as separating wood and plastic for energy production. Similarly, the utilization of various industry waste and side flows is known. In Finland, for example, ethanol production from food industry biowaste has been started. Methanol can also be produced from biomass. [004] Further, various ways of producing bio fuels, such as various hydrocarbons, bio ethanol, bio methanol, and biodiesel, using algae are known. Algae may be grown in waste waters of centers of population, cow houses, piggeries, or similar livestock facilities in which algae produce oil via photosynthesis from carbon dioxide, water and sunlight. Using this process, it is possible to replace plants, such as oil palm, soy, corn, or oilseed rape, with algae in biodiesel production. In addition to waste water or manure carbon dioxide from combustion gases of power plants or similar may be used in the same algae utilizing process. Algae have also been suggested for the production of fertilizers and proteins. [005] However, a feature common to almost all the prior art methods of utilizing municipal waste and industry waste and side flows has been that a certain way of "handling" this waste problem has been chosen. In other words, the main goal has just been to get rid of the waste or side flows with as low expenses as possible. Waste incineration may be mentioned as an example; in some cases, waste incineration is performed at a very low efficiency and, moreover, in such a way that combustion gases are allowed to be d i scha rged i nto th e atmosph ere i n a way th at i n creases environmental load in the form of either only carbon dioxide or possibly many other compounds, in some cases even toxic or almost toxic compounds. Incineration of the waste leads also to, in practice, final loss of nutrients, as combusting the waste or side flows normally means that the phosphorus from the flows remains in the ash that contains heavy metals to such an extent that the ash cannot be used but only as landfill in such a manner that plants cannot use the phosphorus.

[006] In a very similar way, some waste and side flows are carried directly off to landfill sites, where substances in these flows are released into nature and more or less wasted. Similarly, for example, agriculture slurries are transported to be treated together with industrial wastes, which include, for example, heavy metals or similar substances, which prevent solid matter utilization in a large scale. In such a case, for example, phosphorus carried along to community waste water treatment plants handling both community, agricultural and industry waste waters is lost for good, as it cannot be recovered for use as agriculture fertilizer due to heavy metals in the solid matter.

[007] In some more advanced cases, a certain waste flow is taken, for example, to a bio ethanol plant, where specifically bio ethanol is sought to be recovered from the waste, the rest of the end product ending up as waste. If the raw material is, for example, clean bakery waste, waste from an ethanol plant may be further used as livestock fodder. However, if the raw material is some even slightly less pure ethanol raw material, the waste in ethanol production processes has been traditionally taken as waste slurry to municipal waste processing.

[008] In recent years a few patent documents have come up discussing a more comprehensive approach for processing organic waste material. As examples of those documents WO-A2-2009090476, US-A1 -2008135474, and US-A1 -2008050800 may be mentioned, the disclosures of which are fully incorporated herein by reference. [009] The documents teach how organic waste material received from various sources, both agricultural, industrial and community sources, are collected and introduced in a preferred order in a number of different process units, like for instance ethanol plant, algae reactor, anaerobic digester, biodiesel plant, and power plant.

[010] For instance US-A1 -2008050800 discusses a process where the raw materials for the process are, on the one hand corn and grain sorghum, and on the other hand waste water and/or manure from dairy or other livestock facility, and waste water from livestock processing or commercial or municipal waste water sources.

[01 1 ] The corn and grain sorghum are taken to the ethanol plant where the raw material is converted to extracted corn oil (taken to biodiesel plant), ethanol (taken either to biodiesel plant or out of the process), carbon dioxide (taken to algae reactor), wet distiller's grain (taken to livestock facility) and thin stillage or whole stillage (taken to anaerobic digester). In addition to raw material from outside the process, the ethanol plant receives raw material from within the process. From the anaerobic digester the ethanol plant receives biogas and/or methane. From the algae reactor the ethanol plant receives algae solids and algae starch. And from biodiesel plant the ethanol plant receives glycerol.

[012] The algae reactor receives, in addition to the raw material received from the ethanol plant, carbon dioxide, water and nutrients from the anaerobic digester and flue gas from the power plant. The algae solids may be taken, in addition to the ethanol plant, also to the anaerobic digester, the power plant and the livestock facility. The algae reactor may also produce algae oil that may be used at the biodiesel plant.

[013] The anaerobic digester receives as raw material, in addition to those already discussed, waste water and/or manure from the dairy or other livestock facility, waste water from livestock processing or commercial or municipal waste water sources, glycerol from the biodiesel plant, and steam or waste hot water from the power plant. The anaerobic digester produces, in addition to the already listed products, ammonia, biogas and/or methane for the power plant, and biogas and/or methane for the biodiesel plant. [014] The power plant is designed to produce electricity that may be taken out of the process. However, a significant amount of energy fed in the power plant in the form of organic material is needed for various heating purposes in the anaerobic digester, the algae reactor and the biodiesel plant, i.e. within the process itself. The ammonia produced by the anaerobic digester and fed to the power plant is utilized in scrubbing sulphur from the flue gas.

[015] Thus the process, which is very complicated and includes many different technologies and process units, produces ethanol, electricity and biodiesel that can be sold further. I n addition to the already discussed products, the kind of processes discussed above also produces rejectable organic material that may be used as a fertilizer. Very often the solids left over after the treatments at the ethanol plant, the anaerobic digester and/or the algae reactor, if not, for some reason, capable of being used as feedstock for livestock facility, are either combusted or used as a fertilizer. However, a significant problem in the use of the left-over solids as fuel or fertilizer is their high water content. In both cases the left-over solids must, in accordance with the practices of prior art, be dried, which takes a significant amount if not all of their energy content. [016] As to further prior art teachings it should be understood that some prior art documents teach how nitrogen is stripped, or by some other way produced, from ammonia and introduced into the organic solids discharged from the waste treatment facility as fertilizer. Stripping means a simple process where ammonia from the air is scrubbed with sulphuric acid and recovered as a 40% TS (total solids, dry matter) ammonium sulphate solution. Ammonium sulphate is utilized as a fertilizer and/or for soil enrichment production. Here, in and after the fermenting and digesting processes the nitrogen, originating from, for instance, manure is converted, among other processes by, for instance stripping, into such a soluble substance that the plants may fully utilize.

[017] Also, US-A1 -200801 35474 teaches the use of certain species of algae for producing hydrogen that may be used as a fuel. Naturally such an algae reactor has to be a closed one so that the hydrogen may be easily collected. [018] Thus, in spite of the fact that, for instance, the above discussed documents teach a proper way of handling various municipal, industrial and agricultural waste and side flows, such waste treatment facilities have not found any broader acceptance on the market. One of the main reasons is the economical aspect of the waste treatment facility. As taught by the cited documents, a comprehensive waste treatment facility requires a number of different treatment methods and processes having equipment of their own. However, a fact is that the equipment requires complex instrumentation and control of the processes. The waste and side flows have to be brought to the waste treatment facility. And the waste and side flows brought to the site have to be chosen correctly. Thus, both the investments in building and costs of running the waste treatment facility are substantially high compared to the value of the end products normally collected from the waste treatment facility.

[019] It means that every aspect of the building and running of the waste treatment facility, which from now on is called a biorefinery, has to be evaluated in detail such that every problem point is solved by the most economical manner. The challenges are, for instance,

• What kind of waste and side flows to use at the biorefinery,

• On the one hand , the more waste is used the higher is its energy content,

· On the other hand , the more waste is used the more undesirable substances may be found in the waste

• The handling of the inevitably high content of water in the waste and side flows

• The transportation aspect

· The energy balance of the biorefinery

• The marketability or price of the end products,

• The degree of processing of the end products

[020] Thus, an object of the present invention is to raise the state of the art in the area of organic material recycling by introducing a method capable of minimizing at least some problems and drawbacks of prior art.

[021 ] A more detailed object of the present invention is to suggest a way to pick up waste and side flows that may safely be taken to a biorefinery. [022] Another more detailed object of the present invention is to develop a regional waste and side flow processing model, in which a biorefinery for these flows is placed optimally in relation to both waste and side flows and other relevant factors in such a way that it is economically reasonable to both transfer and use the waste and side flows in question and to implement the end products of the process.

[023] Yet another more detailed object of the present invention is to take into account in the positioning of the biorefinery not only the organic waste and side flows, but also other factors having an influence on the economy of the biorefinery.

[024] A further more detailed object of the present invention is to find an affordable solution to the high water content of the waste and side flows.

[025] A still further object of the present invention is to consider the end products of the biorefinery keeping simultaneously in mind both the waste materials used and the end products, and their possible price level.

[026] And it is also an object of the present invention to suggest a biorefinery that is capable of treating all waste and side flows taken therein so that all raw materials may be utilized fully i.e. so that the biorefinery does not create any waste.

[027] The above and other objects of the present invention are reached mainly as presented in the independent claims 1 and 16. [028] Other characteristic features of the invention become evident from the appended dependent claims and the following description of the embodiments of the present invention.

[029] The advantages of the invention include mainly the following:

By applying the present invention to waste water treatment plants, one is able to

• reduce considerably the water returned to the rivers, lakes or seas

• produce cleaner waste waters than before due to

• binding of nitrogen and phosphorus to algae

• not requiring chemical processing

· not making waters eutrophic facilitated fulfilling of emission standards;

carry along the treatment plant slurry to a refining process.

In relation to biowaste recovered separately, the invention instead of incineration, utilizes the valuable fractions:

hydrogen, ethanol and methane

nitrogen and phosphorus.

Thus, in the overall process,

the bio-processing plant of the invention functions by the principles of oil refineries:

valuable fractions are recovered from different steps of the process nutrients are recovered instead of incinerating them

soil depletion is prevented by recovering, among others, phosphorus into a biofertilizer, which reduces the need for chemical fertilizers nutrient cycle becomes more effective (for example, one is able to recover more phosphorus for reuse)

the amount of waste for final disposal is reduced

a regional concept is introduced to minimize transportation (slurry processing and fertilizer transfer)

total energy produced in the process is greater than the energy from separate processes

the amount of waste water leaving the process is decreased, because ash binds moisture into the fertilizer

the process could include two fertilizer lines, one producing organic fertilizer and another non-organic fertilizer

organic fertilizer including phosphorus and nitrogen may be sold for organic farming

ash replaces the potassium as soil enhancing agent

spreading both the fertilizer and the soil enhancing agent simultaneously reduces work at farms and the compaction of the soil.

[030] I n the following, the prior art, the present invention and its operation is discussed in more detail by referring to the appended drawings, of which

Figure 1 illustrates schematically the general operational principle of a prior art waste treatment facility or biorefinery, which has been used as a starting point for the present invention, and

Figure 2 illustrates schematically the process according to a preferred embodiment of the present invention. [031 ] Fig u re 1 shows schematica l ly th e gen eral operationa l pri n ci ple of a comprehensive waste processing system of prior art discussed already above in the introductory part of the specification. In other words, the waste processing system is arranged in connection with the waste processing facility 10, or biorefinery including at least one or more of the following treatment processes: ethanol production in a fermentation reactor, biogas production in an anaerobic digester, algae farming in an algae reactor, biodiesel production, and power generation. The waste processing facility or biorefinery 10 receives as its raw materials industrial waste and side flows 2, municipal waste and side flows 4 and agriculture waste 6 including livestock facility wastes. The end products of the biorefinery 10 include at least some of the following: bio-oil 31 , bio ethanol 32, biogas 33, nitrogen 34, and fertilizer 35. Further, the process may also produce other types of utilizable substances 36, such as, for example, hydrogen or raw material for plastics.

[032] As industrial waste and side flows 2, mainly waste, which include a sufficient amount of organic materials may be considered, such as food industry bio waste, as examples of which waste from bakeries, dairies, breweries and alcohol plants, sugar mills and other food processing plants may be mentioned.

[033] Applicable municipal wastes 4 include municipal waste water treatment slurries and municipal biowaste, which is understood as sorted or separately recovered organic biowaste that is, preferably but not necessarily at the biorefinery, disintegrated and mixed with water or to an appropriate liquid waste or side flow slurry. In other words, the raw materials for biowaste are sorted or recovered such that they are applicable either for organic fertilizer manufacture or at least ordinary fertilizer manufacture. From agriculture 6, various plant derived wastes, such as straws, potato, carrot, Swedish turnip, sugar beet etc. stems and tops etc. , and animal based manu re may be recovered as raw materials. Naturally also the grains, root crops etc. themselves may be used as raw material. Like the municipal biowaste also the above mentioned particulate waste or side flows originating from agriculture are, preferably but not necessarily at the biorefinery, disintegrated and mixed with water or to an appropriate liquid waste or side flow slurries.

[034] Yet another organic raw material for the method of the present invention worth mentioning is fish. For instance, when fishing less valuable fish species from a lake the caught fishes may be used as any other particulate waste material as a source of organic material for the present invention.

[035] However, the processing of the organ ic wastes d iscussed above i n an economically justifiable manner has proven to be in the least challenging.

[036] Firstly, the municipal 4, agricultural and industrial waste and side flows 2 are very often collected in the form of dilute slurries, which is not a problem in the various treatments steps of the biorefinery, but is already a problem at an earlier stage, i.e. when the slurry has to be delivered to the processing plant, mainly because of the transportation costs, whereby thickening of the slurries have to be considered and taken into account. The water content is also a problem when the slurry has passed the processing steps and should be dumped in one way or another. Normally such slurry has still a significant amount of organic solids therein. The solids could thus be used as fuel in a combustion facility or as a fertilizer, but in both cases the solids should be dried.

[037] Secondly, both drying of the solids and the process steps themselves need energy. For instance, both the fermentation step, the anaerobic digester and the algae farming in the algae reactor has its own optimal operating temperature, which may not always be the same as the ambient temperature at the process plant. Therefore the processes have to be heated. Traditionally, the only option for heating the processes or evaporating the water from the waste solids has been to combust part of the ethanol or methanol or any other combustible end or intermediate product of the process or bring energy from outside for the heating purposes.

[038] Thus, to at least take into accou nt the first problem , the location of the biorefinery has to be considered very carefully. The first prerequisite is that the transportation distances of the various raw materials are kept in minimum, which suggests, as one option, that the biorefinery should preferably be located in the suburbs of a town or a city having enough inhabitants to ensure that sufficient amount of various types of municipal waste, and probably also industrial waste is available. However, this is only a part of the solution. Another part that has not been discussed in the cited prior art documents is that the biorefinery should be preferably built in communication or in close cooperation with an industrial facility capable of providing the biorefinery not only with organic waste streams but also waste heat, flue gas, fly or boiler ash etc. In other words, the more synergy can be found between an industrial facility and the biorefinery the better the biorefinery is probably able to meet its economic requirements. [039] In view of the above this specification discusses a pulp and/or paper mill as an example of an industrial facility in communication with which the biorefinery is built.

[040] It is a well known fact that a pulp and/or a paper mill uses a huge amount of fresh water, which is circulated in the numerous stages of the pulp and/or paper making processes until it is dumped back to the environment either as cleaned water of water vapour. Nowadays, the waste waters of the pulp and paper mills undergo efficient separation treatments such that the water discharged back to the waterways is quite clean. However, no matter how efficient the separation treatments are the water still contains some chemical and fiber residues that have to be considered negative in view of the environment. Also the separation that is often performed by various separation techniques including separation ponds results in loss of organic material as the separated solids are most often incinerated in a less economical manner due to the high water content of the organic material. Very often the incineration takes place in a so called bark boiler together with bark, which means, in practice, that the resulting ash contains high amounts of heavy metals and cannot therefore be utilized any more. Sometimes the separated organic material is used as landfill, which means, in practice, waste of organic material and nutrients.

[041 ] It is also a known fact that pulp and/or paper mills produce more heat than they are capable of using. This is because the various processes need high temperature steam, which after having been cooled down in the processes cannot be profitably utilized any more, whereby the low temperature condensates are discharged into waterways, i.e. rivers, lakes or seas. Further, the pulp and/or paper mills, when producing steam for their processes, combust fuels, which results in the formation of both boiler ash, fly ash and flue gas. [042] All these organic waste and side flows, low temperature condensates, boiler ash, fly ash and flue gas can be used in the present invention in such manner that the economy of the biorefinery of the invention is improved to such an extent that building of such a treatment facility in connection with an industrial facility is economically justifiable.

[043] The various waste and side flows of the industrial facility, in this case a pulp and/or a paper mill is used as discussed in the following.

[044] Firstly the organic waste and side flows of the mill containing lignin, celluloses, hemicelluloses, i.e. fibre residues, and filler residues etc. may be used as raw material in either ethanol production or in the anaerobic digester, i.e. the waste and side flows may be utilized in full. An advantageous flow of a pulp mill that can be utilized by the method of the present invention is the filtrate collected from the washer or wash press located after the delignification stage at the pulp mill. The filtrate contains all the organic matter dissolved from pulp to the liquid phase in the numerous washing steps of the pulp mill bleaching and delignification stages. It should be understood that the water collected as delignification filtrate not only contains the organic matter and nutrients dissolved in the delignification but also in at least a few bleaching stages, as the liquid has been brought to the delignification stage washer/wash press counter currently from the bleaching stages. The prior art practice has been to introduce the filtrate of the delignification stage washer/wash press as washing liquid to the brown stock washer from where the filtrate has been taken to chemical recovery, whereby all the organic matter together with the nutrients in the filtrate has been combusted in the recovery boiler. Now, the present invention suggests a novel method of utilizing the dissolved organic matter and nutrients (phosphorus and nitrogen) in the biorefinery.

[045] Secondly, the excess heat from the pulp and/or paper mill may be used to heat the fermentation reactor, the anaerobic digester or the algae reactor to ensure that they are operating in their optimal temperature.

[046] Thirdly, the flue gases of the combustion equipment of the pulp and/or paper mill contain carbon dioxide. The C0₂ can be utilized in the algae reactor for growing algae mass. [047] And fourthly, the boiler and/or fly ash of the industrial facility may be used for drying the solid residue of the biorefinery so that the residue may be used as a fertilizer. Adding of boiler and/or fly ash in the fertilizer does not only dry the fertilizer by binding the water therein, but it also improves the properties of the fertilizer so that the resulting fertilizer may be used not only as a fertilizer but also to replace the use of potassium as the soil improving agent.

[048] As to the use of the solid residue as a fertilizer several facts have to be taken into account. The national or community legislation concerning fertilizers divides the fertilizers into two groups, i.e. organic fertilizers and ordinary or non-organic fertilizers of which only organic fertilizers may be used in organic food production. Further the legislation may either directly or indirectly dictate, for instance, what kind of raw materials may be used in the production of organic and non-organic fertilizers, how the fertilizers have to be manufactured, and what kind of impurities are allowed in the fertilizer and the allowed amount of such impurities. Naturally, the waste materials that may be used in the production of organic fertilizers are bound by stricter requirements than waste materials used in the production of non-organic fertilizers. Now that there is a high demand for organic fertilizers on the market, it makes sense to aim at organic fertilizer production, and use only such waste and side flows for non-organic fertilizer production that cannot be used for organic fertilizer production.

[049] Thus, it has to be understood that when selecting raw materials for the waste treatment process all the requirements of all the products resulting from the biorefinery has to be taken into consideration. Thus, for instance the use of waste material from slaughter houses is in many countries forbidden in the manufacture of organic fertilizers, but after processing the products of slaughter houses further to hams, sausages etc. they can be used as raw material in the biorefinery even in the production of organic fertilizers. Also domestic or community waste water slurries originating from municipal waste water treatment plants cannot be used in many countries in this kind of a biorefinery in the manufacture of organic fertilizers, as, for instance, their origin is not controlled well enough. However, such slurries can be used to produce non-organic fertilizers. In other words, only well controlled organic waste materials and side flows may be used in the production of organic fertilizers. [050] I n practice the above means that industrial waste waters having organic material and separately collected bio wastes may be used in the production of both organic and non-organic fertilizers whereas the community waste slurries may be used in the production of non-organic fertilizers only.

[051 ] Thus one way to improve the possibilities of the biorefinery of the invention to accept a wider variety of waste flows to be processed is to provide the biorefinery with two more or less separate production lines. One production line is producing organic fertilizer and the other line producing non-organic fertilizers. As to the other end products of the biorefinery, like ethanol, biogas, hydrogen, etc. they can be collected as long as the process steps they are produced are kept separate.

[052] Figure 2 illustrates schematically a biorefinery in accordance with a first and a second preferred embodiment of the present invention. The biorefinery has now been divided into three sub-processes: bio ethanol production 12 by a fermentation process, biogas production in an anaerobic process 14, and algae farming in an algae reactor 16. In the biorefinery, various end products and energy in the form of heat and electricity are recovered from various raw materials using different processes. The bio ethanol production 12 receives, in this embodiment of the present invention, carbohydrate rich waste liquid 21 from a sugar mill, i.e. in a broader sense side flow from food industry, and sorted municipal bio waste 41 as raw materials most suitable for ethanol production. The ethanol production may also utilize algae mass from algae farming. Naturally it is clear that the bio ethanol production may also be run with only one waste or side flow without a need to use wastes from several sources. The bio ethanol production 12 mainly produces bio ethanol 32 and mash by using microbes in its fermentation process. The mash is preferably taken to the anaerobic biogas digester or production 14-i to be used as one of its raw materials.

[053] Mash is, in practice, such waste from the bio ethanol 12 production that has been cleaved by microbes into a form where it is easy to be utilized at the anaerobic biogas production 14-|. Other biogas production 14-i raw materials include, i n th is exemplary embodiment, residual fibre slurries 22 of a paper and/or pulp mill, bio slurries 23 from the waste water treatment of the paper and/or pulp mill, as well as algae mass received from the algae farming Naturally it is also clear that the bio gas production may also be run with only one waste or side flow without a need to use wastes from several sources. The anaerobic biogas production 14-i produces biogas 33, which may, as a preferred alternative of the present invention, be incinerated for producing district heat and electricity. Naturally, the heat of the incineration plant may also be used for various purposes requiring heating at the biorefinery itself, if needed.

[054] The anaerobic biogas digester ^ ^ also produces residual or waste slurry, the thickening of which produces filtrate, which is taken to the algae reactor. However, as algae are able to utilize only a certain amount of nitrogen, some nitrogen has to be removed from the liquid circulation. The nitrogen is separated as ammonium sulphate 34 in a further denitrification reaction (some of the many useful alternatives include air stripping and H₂S0₄ scrubbing). Bio fertilizer or organic fertilizer 35i is produced from the residual slurry when combined with, for instance, ash 25 from the pulp and/or paper mill and, preferably but not necessarily, also with the above mentioned ammonium sulphate 34, in a broader sense, with a n itrogen compou nd received from the biorefinery processes. Additionally, filtrate is collected from the biogas production 14-i, when the anaerobic biogas digester 14-i receives algae mass from the algae reactor 16i and thickens such to the dry matter appropriate for the biogas production 14-|. The collected filtrate is returned to the algae reactor Algae reactor 16i receives also nutrients in connection with the filtrate/s 24 of the paper or pulp mill. Excess water, if such is created in the algae reactor may be taken to the waste water treatment ponds 23 of the pulp and/or paper mill.

[055] As should be understood from above the waste treatment process capable of producing organic fertilizer was discussed as the first preferred embodiment of the present invention. However, to be able to utilize also the waste slurries 42 from a municipal waste water treatment facility or slaughterhouse waste, for instance, the biorefinery of Figure 2 is provided, as the second preferred embodiment of the present invention, with another anaerobic biogas digester, i.e. a second anaerobic digester 14₂, which receives, in this embodiment, as its raw material residual fibre suspensions 22 of a paper and/or cellulose mill, municipal waste slurries 42 originating from municipal waste water treatment facility, bio slurries 23 from paper and/or cellulose industry, as well as algae mass received from a second algae reactor 16₂. The second anaerobic digester 14₂ produces biogas 33, which may, as a preferred alternative of the present invention, be incinerated for producing district heat and electricity. Naturally, the heat of the incineration may also be used for various purposes requiring heating at the biorefinery itself, if needed. The biogas received from the second anaerobic biogas digester 14₂ may be combined with the biogas from the first anaerobic biogas digester

[056] The second anaerobic biogas digester 14₂ also produces residual slurry, the thickening of which produces filtrate, which is taken to the algae reactor. However, as algae are able to utilize only a certain amount of nitrogen, some nitrogen has to be removed from the liquid circulation. The nitrogen is separated as ammonium sulphate 34 in a further denitrification reaction (some of the many useful alternatives include air stripping and H₂S04 scrubbing). Non-organic fertilizer 35₂ is produced from the residual slurry when combined with, for instance, ash 25 from cellulose industry and, possibly, also with the above mentioned ammonium sulphate 34. Additionally, the second anaerobic biogas digester 14₂ when receiving algae from the second algae reactor 16₂ creates filtrate by thickened the algae mass. The filtrate is returned to the second algae reactor 16₂. And finally, the second algae reactor 16₂ receives nutrients in connection with the filtrate 24 of the paper and/or cellulose mill. Excess water, if any, from the second algae reactor 16i may be taken to the waste water treatment ponds 23 of the pulp and/or paper mill. [057] If the biorefinery is designed to be able to produce both organic and nonorganic fertilizer in two parallel process lines the facility needs two biogas plants, as the flows not acceptable for organic fertilizer production, like for instance slurries 42 originating from the municipal waste water treatment facilities or slurries produced by disintegrating slaughter house waste, has to be kept separate from the cleaner and more controlled slurries of the biorefinery. The need for a second algae reactor has to be considered on case-by-case basis. Depending on the quality of the municipal waste water slurries 42 it is possible, as the third preferred embodiment of the present invention, to manage with a single algae reactor common to both process lines. This thinking is mainly based on the fact that algae themselves do not bind any harmful compounds from the liquid it receives from the second anaerobic biogas digester 14₂, whereby the algae mass could, then, be introduced from the single algae reactor to both anaerobic digesters 14-i and 14₂, as well as to the ethanol production 12, too. Thus, when the amount of harmful compounds or substances in the municipal waste water is small, the content of the compounds or substances in the water left in the algae mass carrying such compounds to the anaerobic digester 14-i is so low that the fertilizer fulfils the requirements set for an organic fertilizer.

[058] At this stage it has to be, however, understood that the biorefinery of the present invention may have several variations, i.e. other embodiments, which will be discussed briefly in the following.

[059] In spite of the fact that the above discussed first three preferred embodiments of the biorefinery teaches that the residual slurry from the anaerobic digester 14 i.e. that of the biogas production forms the basis of the fertilizers, for both the organic and the non-organic fertilizers, it is also possible, as a fourth preferred embodiment of the present invention, to produce the fertilizer from the residual slurry of the ethanol production 12, i.e. from the mash by combining the mash with, for instance, ash. In such a case, in its simplest form the biorefinery may be formed of the mere ethanol production unit, and the fertilizer production unit, if the equipment needed for treating the incoming and outgoing flows are left out of the discussion. It is, however, advantageous, as the fifth preferred embodiment of the present invention, to provide the above discussed simple biorefinery with an algae reactor 16 working together with the ethanol production 12, as an algae reactor is able to produce raw material for the ethanol production very efficiently. In a similar manner, the biorefinery may be formed of a single anaerobic digester 14 and the fertilizer production unit if the equipment needed for treating the incoming and outgoing flows are left out of the discussion. Thus, it could be said that the simplest biorefinery is formed of a bioreactor (either fermenter for ethanol production or anaerobic digester for biogas production) and the fertilizer production unit. It may also be formed of two parallel bioreactors

[060] Also, as a sixth preferred embodiment of the present invention, the biorefinery of the second and third preferred embodiments may have an ethanol production arranged prior to the anaerobic digester 14₂. In other words, the anaerobic digester receives mash from the ethanol production, and the ethanol production may receive slurries not acceptable for organic fertilizer production.

[061 ] And finally, it is also possible in some cases that the anaerobic digester/s is/are used either alone or together with the fermenter/s of the ethanol production without an algae reactor, whereby all waste and side flows brought to the biorefinery are introduced to the anaerobic digester/s and/or to the ethanol production, which have to manage without algae mass.

[062] One of the main reasons why the organic residual slurry of the biorefinery is mixed with ash to be used as a fertilizer is the legal requirement that the slurry has to be dried. In other words, the spreading of a fertilizer in the form of slurry is not allowed. As discussed already earlier this is not a problem in view of the present invention as the ash of the industrial facility, or ash at least partially brought elsewhere, is used for drying the slurry. When doing that the fertilized gets its granular appearance and the fertilizer may be used to replace not only the industrial fertilizers but also the use of potassium.

[063] However, it has to be ensu red that the chem ical com position of ash is appropriate to be added in the fertilizer. For instance, ash contains normally heavy metals (Cd, Cu, Cr, Pb, Ni, Zn, As, V) that originate from the combusted fuel. The national or community legislation limits the contents of heavy metals in the fertilizers. In practice, if the cadmium/phosphorus ratio in the residual slurry - ash mixture is low enough the mixture may be used as the fertilizer. The ordinary heavy metal content in ash results normally in too high a concentration of heavy metals in the fertilizer, whereby heavy metals should be removed from the ash. Article "Theoretical Feasibility for Ecological Biomass Ash Recirculation: Chemical Equilibrium Behavior of Nutrient Elements and H eavy Metals during Combustion" in Environmental Science & Technology, vol. 31 , No. 9, 1997 teaches that heavy metals adhere to small and light ash particles in connection with high temperature combustion and, based on that behavior may be separated from fly ash by means of a hot cyclone. Thereby, prior art teaches an affordable way of treating fly ash so that the heavy metal content therein is reduced to such a level that when added to the fertilizer, or actually to the residual slurry of the ethanol or biogas production, the heavy metal content in the fertilizer remains in acceptable level.

[064] Thus to be able to utilize the ash of the industrial facility the facility must have, or has to be provided with, means for separating heavy metals from ash, unless the ash is originally substantially free of heavy metals. Thus, in normal conditions, if the hot cyclone process is used to separate heavy metals, the heavy ash fraction of the hot cyclone may be used in the fertilizer production. Naturally, the same requirement applies to ash brought from elsewhere. In such a case, the ash has to be treated to remove heavy metals at the combustion facility where it is created or at the biorefinery i.e. the heavy metal separation has to be arranged at the biorefinery. [065] However, the use of ash, preferably fly ash, though boiler ash is another option, too, is not the only way of drying and granulating the residual slurry from the anaerobic digester and/or the ethanol production but also peat, straw, bark etc. may be used. In other words all organic water binding materials may, after having been disintegrated to appropriate coarseness, be used for drying and granulating the residual slurry, as long as the resulting product meets the requirements set for fertilizers.

[066] The fertilizer production forms one further prerequisite for the location of the biorefinery. Naturally, it, again , relates to the transportation and storage of the fertilizers. In other words, it is advantageous if the farms and the like using the fertilizers were so close to the biorefinery that no separate transportation and storage arrangement were needed . However, normally th is is not a problem , as if the biorefinery uses manure from livestock facility as one of its raw materials, the biorefinery is close to the livestock facility, which most probably means that the facility is close to farms needing fertilizers, too.

[067] The applicability of the present invention has been studied by means of the following example. The biorefinery of the present invention is located in communication with a pulp mill located nearby two towns having 70000 inhabitants altogether. The towns have smallish food industry and the surrounding countryside including the parks and other green areas of the towns has a field area of 30 000 hectares. The fields are located at an average d istance of less than 25 km 's from the biorefinery. The applicable waste and side flows are mainly sufficient for providing the field area all the fertilizer they need. Thus, it is obvious that the produced fertilizer does not need any additional transportation or storage facilities. Also, the waste heat produced by the pulp mill is sufficient for the various heating purposes of the biorefinery, whereby the hydrogen, ethanol and/or methanol the facility produces may be sold either as is or in the form of district heat and/or electricity. Also, calculations show that, in practice, all the water introduced into the biorefinery may be bound in the fertilizer with the ash, whereby there are hardly any effluents from the pulp mill to the waterways. [068] As to the use of algae, the above specification uses a term "algae reactor". The term covers all algae farming options. The algae may be grown in open ponds where the cultivation is highly dependent on local weather conditions. Also, the optional production of hydrogen in open or even covered ponds is questionable. Another way of cultivating the algae is to use photo-bioreactors, which are normally closed transparent tubes arranged in buildings designed therefor. In cases where photo-bioreactors are used, algae with high oil content or high hydrogen production capability may also be grown. In that case, oil could be extracted and refined for biodiesel; the hydrogen may be used as fuel and the residue algae mass used for ethanol or biogas production. Similarly, although it has not yet been expressly stated it is possible and in some cases very likely that there are more than one algae reactor and, as a further option, that the algae in the reactors are of different algae species. Different types of algae may be needed for producing different products (oil, hydrogen, etc.). [069] In light of the above, it is to be understood that the above mentioned biorefinery is preferably built in connection or at least in close communication with one or more industrial facilities offering synergistic advantages. A starting point could be that the biorefinery of the invention is placed to the proximity of an incineration facility, in which oil, peat, wood, natural gas or the like is incinerated. This is due to the fact that an essential part of the invention is the utilization of carbon dioxide in the algae reactor. The long-distance transfer of C0₂ in a scale corresponding to the needs of an algae reactor of the invention is more than questionable. Similarly, the long distance transfer of possible condensate or waste heat of the incineration plant is difficult. Also further, fly or boiler ash for drying the solid matter left from ethanol or biogas production is available from these facilities. Thus, the surroundings of a pulp and/or a paper mill are a very advantageous alternative for positioning the biorefinery of the present invention. Additionally, the pulp and/or a paper mill produce various filtrates including organic matter that may be efficiently utilized in the present invention. In the pulp and/or paper mill filtrates, side flows or waste flows, it is the cellulose from wood, recycled paper, broke etc., and lignin and other organic compounds that have dissolved from the wood, which form an attractive raw material for the ethanol and/or biogas production. In addition to the organic matter the waste and side flows of a paper mill may also contain various fillers, which may be introduced to the fertilizer production, and taken to fields to be used as soil enrichment product. Nowadays it is common practice to take the fillers, mostly calcium carbonate, to landfill. [070] It is to be noted that above only a few most preferred embodiments of the present invention have been discussed. Thus, it is obvious that the invention is not restricted to the above described embodiments, but it may be applied in many different ways within the scope of the appended claims. The features of the present invention described in relation to a certain embodiment are within the basic concept of the invention, whereby they may be used in connection with another embodiment of the invention. Thereby also different features of the invention may be used in combination provided that such is desirable and the technical possibilities for that are available.

Claims

1 . A method of processing organic side flows and waste slurries in connection with a bio refinery arranged in communication with an industrial facility, the organic side flows and waste slurries comprising at least one of industrial waste slurries, municipal bio waste slurries, municipal waste waters and agriculture slurries, the bio refinery comprising at least one of the following: ethanol production, bio gas production, and algae farming to produce residual organic slurry and at least one of hydrogen, bio ethanol and bio gas,

characterized by

• treating the waste slurries in at least one of a ethanol production (12) and biogas production (14^ 14₂) to produce ethanol and/or biogas and residual organic slurry, and

• combining the residual organic slurry with an applicable drying agent for drying the slurry and for producing a granular product (35) capable of being used as a fertilizer and/or a soil enrichment agent.

2. The method as recited in claim 1 , characterized by using, in the fertilizer/soil enrichment agent production, as the drying agent, ash, peat, straw or bark such that the fertilizer/soil enrichment agent contains an allowable amount of heavy metals.

3. The method as recited in claim 1 or 2, characterized by introducing in a first anaerobic digester (14-i) at least one of agriculture slurries, food industry slurries (21 ), pulp and paper industry fiber slurries, filtrates and side flows (22, 23) and municipal bio-waste slurries (41 ), whereby the produced fertilizer is an organic fertilizer (35i).

4. The method as recited in claim 1 or 2, characterized by introducing in the ethanol production (12) at least one of agriculture slurries, food industry slurries (21 ), pulp and paper industry fiber slurries, filtrates and side flows (22, 23) and municipal bio-waste slurries (41 ), whereby the produced fertilizer is an organic fertilizer (35i).

5. The method as recited in claim 3, characterized by introducing one or more of the agriculture slurries, food industry slurries (21 ), pulp and paper industry fiber slurries, filtrates and side flows (22, 23) and municipal bio-waste slurries (41 ) to ethanol production (12) prior to the first anaerobic digester (14-i).

6. The method as recited in claim 3, characterized by introducing algae mass from a first algae reactor (16i) to the first anaerobic digester (14-i).

7. The method as recited in claim 4 or 5, characterized by introducing algae mass from a first algae reactor (16i) to ethanol production (12).

8. The method as recited in claim 3, 4 or 5, characterized by collecting the filtrate from a washer/wash press after the delignification stage at a pulp mill.

9. The method as recited in claim 1 or 2, characterized by introducing, possibly in addition to waste slurries or side flows or filtrates from other sources, in a second anaerobic digester (14₂) waste slurry (42) from a municipal waste water treatment and/or waste slurries not applicable for organic production, whereby the produced fertilizer is a non-organic fertilizer.

10. The method as recited in claim 9, characterized by introducing algae mass from a first algae reactor (16i) to the second anaerobic digester (14₂).

1 1 . The method as recited in claim 9, characterized by introducing algae mass from a second algae reactor (16₂) to the second anaerobic digester (14₂).

12. The method as recited in claim 6, 7, 10 or 1 1 , characterized by thickening the residual slurry prior to fertilizer production by removing nitrogen containing filtrate therefrom and by separating nitrogen from the removed nitrogen containing filtrate prior to taking the filtrate to algae reactor (16).

13. The method as recited in claim 12, characterized by introducing the separated nitrogen to the fertilizer (35i, 35₂).

14. The method as recited in claim 6, characterized by thickening the algae mass prior to its introduction to the ethanol production (12) or biogas production (14-i, 14₂) by removing nutrient containing liquid therefrom and returning the nutrient containing liquid to algae cultivation (16).

15. The method as recited in claim 1 or 2, characterized by removing heavy metals from the drying agent prior to mixing the drying agent with the residual slurry.

16. A fertilizer, characterized in that it is formed of residual slurry collected from at least one of ethanol production (12) and biogas production (14-i , 14₂) and a drying agent.

17. The fertilizer, characterized in that the drying agent is ash or disintegrated peat, straw or bark.

18. The fertilizer, characterized in that the raw material of the ethanol production and/or biogas production is at least one of waste or side flow or filtrate of a pulp and/or paper mill, waste or side flow or filtrate of food industry, waste slurry or manure of agriculture, community bio waste slurry and community waste water slurry.