FR2710052A1 - Sewage sludge enriched with nutrients, mixtures and methods and their use. - Google Patents

Abstract

The invention relates to sewage sludge for spreading on agricultural and horticultural surfaces or other cultivation surfaces, which are characterized in that they contain added nutrients selected from C, N, P , Na, K, Ca, Mg, Fe, Mn, Zn, Cu, Co, Mo, B, Si, Al, O, Cl and S, their use as fertilizer in agriculture as well as corresponding processes, mixtures of nutrients their preparation and use.

Description

The present invention relates to sewage sludge enriched with

  nutrients and in particular nutrients which are suitable for the total supply of nutrients to soils used in agriculture or horticulture or other growing areas, for example in landscape architecture, without fertilizer or supplemental traditional manure, as well as their use for this purpose and that processes and

  mixtures of nutrients for their preparation.

  During the biological purification of wastewater in the installations

  using anaerobic or aerobic processes, in particular

  using the activated sludge process, it appears as final products of

  sludge called sewage sludge that must be removed.

  The major problem that arises during the disposal of sludge

  ratio-n lies in the extraordinarily large quantities: in the case of the biological purification of communal wastewater in facilities

  daily, per capita, about 3 liters of sludge

  which, in the case of Federal Germany, corresponds to an annual production of about 65 million tonnes of sewage sludge

  dry matter of about 5% by weight.

  Sewage sludge from municipal wastewater treatment plants

  In addition, there are significant quantities of sewage sludge from industrial wastewater, the composition of which differs more or less substantially from that of municipal sewage sludge (eg sewage sludge).

  from dairies, paper mills, etc.).

  Currently, in many cases, following dehydration or conditioning pretreatment, these quantities of sewage sludge are eliminated in Germany in proportions that differ according to the region: approximately 10 to 20% of the sewage sludge about 30% are landfilled and about 30% to 60% are recovered from agriculture,

  that is, spread on agricultural useful surfaces.

  The composition of the sewage sludge depends on the nature of the wastewater and the treatment method used. In the case of sewage sludge from biological treatment plants, primary sludge or fresh sludge, which is separated following the first treatment stage, is distinguished,

  for example by sedimentation, secondary sludge, which comes from

  biological sludge, in particular activated sludge, excess sludge, percolating bed sludge etc., as well as tertiary sludge from the third treatment stage of treatment plants, eg

  flotation or flocculation and precipitation.

  This sludge consists of 95 to 97% or more of water. The organic fraction is between 45 and 75% in the case of primary and secondary sludge and between 20 and 60% in the case of tertiary sludge, relative to the dry mass (DM). Sludge is particularly interesting because of

  their biomass which consists of a complex mixture of many

  microorganisms (bacteria, protozoa, fungi and multicellular animals). As a result, most of the organic substance of the sewage sludge comes from such organisms or their remains as well as their excretion and degradation products, constituted for example by amino acids, proteins, carbohydrates, etc. Because of the high water content of the sludge, and the presence of germs and pathogenic organisms such as viruses, bacteria, fungi, worm eggs, nematodes, etc., the sewage sludge is conditioned and then dehydration that leads to stabilization, a significant reduction in volume and in many cases to sanitation, that is to say to the destruction of

  germs and pathogenic organisms. This conditioning is accomplished main-

  by adding lime-based products such as lime milk or pulverized white lime to the sludge. In addition, salts are also added

  iron or aluminum. Thanks to these additions, the cell membranes of micro-

  The organisms are destroyed so that their pathogenicity is eliminated and, on the other hand, the sewage sludge is thus put into a form in which it can be more easily thickened and dehydrated, which is done mainly by centrifugation or compression. Dehydration can be followed by a heat or chemical treatment (for example with CaO) for

  sanitation or disinfection.

  The organic substances in the biomass contained in the sewage sludge and which are likely to form humus, as well as the contained nutrients, the type and quantity of which depend on

  determined limits of the origin and type of wastewater, make sludge

a valuable product.

  A typical sewage sludge with a dry matter (DM) content of about 35% and stabilized with lime, for example, has the following nutrient composition (source: Faustzahlen fur Landwirtschaft und Gartenbau, 12th edition, 1993, Verlagsunion Agrar, Landwirtschaftsverlag Münster-Hiltrup, page 288): (g / kg DM) CaO 337 (249 - 432) N total 23 (18 - 28) N (deNH4) 1 (0-2)

P205 24 (17 - 36)

K20 2 (1 - 4)

  MgO 6 (5-8) Cu 131 (87-205) Zn 447 (327-669) - Mn 371 (300-483) Mo 3.1 (1.9-4.3)

B 34 (26 - 49)

  To this may be added Fe, Na and S. According to the regulations in force in Germany concerning sewage sludge (Verordnung iber das Aufbringen von Klirschlamm [AbfKlarV] von 1992; Novelle zur Klârschlammverordnung BGB1 I, Jahrgang 1992, pages 912-934), limit values for the allowable levels of heavy metals of sewage sludge and soil are as follows: In sewage sludge In soil (mg / kg DM) ( mg / kg MS) Lead 900 100 Cadmium 10 1.5 Chromium 900 100 Copper 800 60 Nickel 200 50 Mercury 8 1 Zinc 2 500 200 Whereas previously communal sewage and thus also sewage sludge sometimes contained sensitive loads of heavy metals, municipal sewage sludge currently has, as a general rule, such low levels of heavy metals, which lie well below the legal limit values indicated above, that they can be used without any problem in

  Agriculture. This is true also for harmful organic substances.

  The disposal of sewage sludge by landfilling and incineration

  ration is neither economic nor ecological, because in both cases the biomass is not valued. In addition, incineration is linked to undesirable additional energy consumption and the undesirable formation of carbon dioxide, not to mention the formation of other harmful harmful substances, for example dioxins and residue consisting of 50% ash. In addition, an increase in the amount of sewage sludge to be incinerated does not seem absolutely realistic because the capacities of the incineration plants that are available in Germany are not sufficient for the current production.

of waste.

  Sewage sludge does not constitute unwanted waste but valuable products that can be used especially in agriculture, and especially as the nutrients they contain, especially in the case of sewage sludge. dehydrated, are present mainly under a

  form favorable to plants and can be introduced into the soil.

  The quantity of sewage sludge that can be applied is limited since 1 July 1992 by the Regulation on sewage sludge to a maximum of 5 t DM / ha every 3 years, and the limit values for the heavy metals content of sewage sludge and soil must not be exceeded. This assumes the accurate analysis of sewage sludge and soil. The costs incurred by

  these studies are the responsibility of the operator of the treatment plants.

  The same principles are also valid for the compost of sewage sludge and garbage which contains, apart from the precious biomass, nitrogen, phosphorus, potassium, calcium, magnesium, etc. contents. which are effective from the point of view of fertilization. In this case, the quantity

  spreading is legally limited to a maximum of 10 t MS / ha every 3 years.

  This makes it possible to avoid damage to the soil, plants, animals and humans during the agricultural valorisation of sewage sludge, especially since it has been verified, even in the case of repeated application of sewage sludge, it was impossible to demonstrate enrichment effects

heavy metals in the soil.

  The spreading of sewage sludge on agricultural useful surfaces according to

  the regulation on sewage sludge is part of the state of the art.

  In the case of this traditional valorization of sewage sludge in agriculture, the sewage sludge is spread directly on agricultural useful surfaces in the form in which they appear, in particular in conditioned or dehydrated form, without any addition of effective constituents. from the point of view of fertilization. According to the state of the art, the farmer, on the basis of the analysis of his soil and the spreading sewage sludge, has to compensate by separate additional fertilization the need for fertilization which is felt for the cultivation of a type of crop plants planned or for crop rotation planned. This has the disadvantage that not only farmers

  machines, working time and extra money

  In order to achieve a corresponding additional fertilization, it is also important that the repeated passage of vehicles over the agricultural usable surfaces leads to a settlement of the soil which is highly undesirable. For these reasons, it will be understood that this recovery of sewage sludge in agriculture still does not meet an insufficient reception although it is a biological material quite appropriate. Thus, according to the state of the art, it was unknown until now that it is possible to use sewage sludge as the sole means of fertilization, especially since the composition of sewage sludge varies. according to their origin and that fertilization requirements depend to a very large extent on the

place, soil and type of crop.

  The present invention aims to propose a new form of sewage sludge which is enriched in nutrients or optimized in terms of their nutrient content and which are therefore suitable for the targeted supply, preferably single, of substances nutrients to soils used in agriculture and horticulture and other growing areas, without additional traditional fertilization and their corresponding use and

  processes and mixtures of nutrients for their preparation.

  The sewage sludge according to the invention is intended in particular for spreading on useful agricultural or horticultural surfaces, but also on other types of cultivation surfaces, for example re-cultivation surfaces, replanting surfaces. , reforestation surfaces, etc., and to be used in landscape architecture. They are characterized in that they contain, in addition to their naturally occurring constituents, added nutrients which are selected from C, N, P, Na, K, Ca, Mg, Fe, Mn, Zn, Cu, Co, Mo, B, Si, Al, O, Cl and S. In the context of the present invention, the term "sewage sludge" refers in particular to the sewage sludge already used up to now as a substrate depending on the state of the sewage sludge. technical, that is to say especially pre-dehydrated sludge or dehydrated and conditioned. However, in the context of the invention, it is also possible to use other sludges of any type that come from pre-purification stages or directly from biological treatment stages of purification plants, as well as sludge from water treatment plants and industrial purification plants. As part of

  the invention, it is also possible to use so-called sludge with no load, that is to say

  to say sludge which, apart from organic biomass, contains practically no appreciable content of mineral substances effective from the point of view of fertilization. The sludge may come from wastewater treatment plants intended for the treatment of domestic wastewater or communal wastewater and / or industrial wastewater relatively low in harmful substances. It is also possible to use as mixtures

  sewage sludge as well as composts of sewage sludge and garbage.

  From the point of view of transport costs and ease of spreading, it is preferred according to the invention the sewage sludge that is capable of flowing. In

  also include treatment products for sewage sludge

  dantes, which appear for example during thermal dehydration or

  thermal drying, and which consist for example of granules.

  According to a first aspect, the concept of the invention is based on

  sewage sludge with nutrients, which are added under

  a suitable form, to satisfy the corresponding needs of the soil.

  According to a second particularly important aspect of the present invention, the type and proportions of the main and trace nutrients added to the sewage sludge are quantitatively selected, taking into account the soil and water analysis. analysis of sewage sludge, in a manner that is specific to the soil and crop type, to satisfy approximately or

  exactly the demands in fertilization for a given duration.

  The sewage sludges according to the invention are characterized in that they have the following contents of main nutrients, each reported to the dry mass (DM) of the sewage sludge used: (g / kg DM) N total: <300, preferably <50, more preferably <20 CaO: <800, preferably <500 MgO: <90, preferably <30, more preferably <15 K20: <90, preferably <50 P205: <160, preferably <80, more preferably <50

S: <30, preferably <3.0.

  In addition, the sewage sludge according to the invention are characterized in that they have the following contents of trace nutrients, each reported to the dry mass (DM) of the sewage sludge used: (g / kg of MS) B: <16, preferably <1.1, more preferably <0.1 Cu: <12, preferably <0.8, more preferably 0.4 Fe: <30, preferably <3.0 Zn: <30, preferably <2.5, more preferably <1.5 Na: <30, preferably <0.3 Mn: <36, preferably <0.5, more preferably <0 25 Mo: <12, preferably <0.15, more preferably <0.01

Cl: <1, preferably <0.3.

  Of course, in the tables above, all the listed nutrients can not simultaneously exhibit a concentration

nothing.

  According to the invention, the amounts of the main and trace nutrients specified above may be in the range of 0 to the upper limit indicated in each case. Depending on the soil to be treated and the sewage sludge used, some of the nutrients listed above may be absent and the sewage sludge according to the invention may contain only major nutrients or

  only trace nutrients.

  The main source of sewage sludge used as a substrate

  according to the invention is constituted by the sewage sludge which comes from the treatment

  household wastewater and communal wastewater. These sewage sludges are characterized, particularly in the case of large plants, by a particularly marked constancy of their composition. This is also true for sewage sludge from industrial wastewater, including zero-load sludge consisting almost exclusively of biomass and possibly conditioning agents, in particular lime. Advantageously, the sewage sludge according to the invention has a solids content of about 25 to about 95% by weight and preferably about 25 to 50% by weight. Depending on the stage of treatment, these sludges preferably have a solids content of 25 to 35% by mass (pre-dehydrated sludge) or about 35 to 50% by weight (sludge stabilized with lime or dehydrated still), in each case in relation to the

  dry mass (DM) of the sludge used.

  The essential aspect of the present invention lies in the optimization of the nutrients of the sewage sludge, which is carried out in a manner specific to the soil and specific to the types of culture or succession of crops. As indicated above, the Regulation concerning

  sewage sludge for Federal Germany requires an analysis of the sludge

  and a soil analysis of the surface on which the sludge is to be applied. According to the state of the art, on the basis of the difference in nutrient levels between soil and sewage sludge, the farmer can

  determine the type and amount of fertilizer to be applied in addition and separately

  is lying. In the context of the invention, according to the second aspect of the concept of the invention, the purification sludge enriched in one or more main nutrients and / or in one or more trace nutrients substantially corresponds or exactly to the soil fertilization requirements that result, for the type of crop envisioned or for the intended crop succession, from the amount of application and the legislated waiting time until the next application of sludge. purification. As a result, it is possible according to the invention to provide, in the form of a manure which is preferably unique by means of sewage sludge, the necessary quantity of all the main and trace nutrients which are needed for manure, preferably for effective fertilization over several years, without the need for further fertilization. Thus, the sewage sludge which is particularly preferred according to the invention are characterized in that their contents in one or more main nutrients and / or in trace amounts are adjusted in such a way that the quantities of substances corresponding nutrients that are provided by a single, preferably single application, and by a given amount of spreading of the sewage sludge correspond approximately or exactly to the fertilization requirements of the soil to be fertilized by the sewage sludge for a period of time. predetermined. The person skilled in the art knows that, in many cases, it is not possible to carry out a single fertilization with regard to nitrogen, especially for more than one growing season, in particular because of the losses of nitrogen that occur and nitrogen requirements that vary over time depending on the phase of

growth.

  In these cases, the sewage sludge according to the invention does not contain the amount of nitrogen corresponding to all the nitrogen requirements of the soil in question, but a smaller quantity which must then be completed separately.

  by the operator of the soil in question, according to the needs that appear.

  With regard to the other nutrients of sewage sludge according to the invention, a real optimization is possible and preferable in

all cases.

  However, in the case of multiple spreading of sewage sludge according to the invention, it is in principle also possible to carry out an optimization

as regards nitrogen.

  For agricultural, technical, ecological and soil mechanics reasons, it is particularly favorable to apply the planned quantity of sewage sludge, which preferably corresponds to

  not necessarily at the maximum allowable amount.

  However, it is also possible to carry out spreading

  sewage sludge according to the invention, in particular when the succes-

  crop production is not fully determined. In this case, the sum of the nutrient inputs from the different spreads corresponds to the

  soil fertilization requirements, possibly after correction of nitrogen losses.

  When a multiple application of sewage sludge is provided, the contents of the sewage sludge according to the invention in one or more main nutrients and / or in trace amounts are adjusted so that the sum of the amounts of the sewage sludge is concerned nutrients applied in a multiple application for a predetermined time or in several spreads at predetermined intervals, a predetermined amount of sewage sludge corresponds approximately or exactly to the fertilization requirements of the soil to be fertilized by the sludge for a predetermined period of time or

  during the period corresponding to the intervals between the spreads.

  The determination of fertilization needs is known to the man of the

  job. This determination can be made by proven methods.

  According to one particularly preferred embodiment of the invention, the sewage sludge is characterized in that its contents of one or more main nutrients and / or trace amounts are adjusted in such a way that quantities of the relevant nutrients that are applied during the single application of a specified quantity of sewage sludge, preferably the legally permitted maximum spreading quantity, currently 5 tonnes DM / ha, for a period of The predefined rate, which is the legal waiting time until the new application of sewage sludge, which is currently 3 years, corresponds to the fertilization requirements of the soil to be fertilized with sewage sludge. Thus, these sewage sludges are specifically optimized for sewage sludge and soil, in the case of the maximum permissible quantity of sludge spreading.

  treatment for a given waiting time.

  The sewage sludge according to the invention is precisely defined in the legal sense, even in the case of the particularly preferred embodiment, described above, of the optimization of soil and crop specific nutrients, given that the development and evaluation of soil and

  activated sludge are in themselves familiar to those skilled in the art and that a sludge

  According to the invention, which consists of a specific soil and crop, coincides clearly and quantitatively with these analyzes. Such soil surveys are conducted by accredited testing institutes that also establish nutrient requirements for a prescribed agricultural operation, possibly in conjunction with agricultural services.

  competent authorities under the Regulation on sewage sludge.

  This embodiment of the invention is particularly advantageous

  because the farmer does not have to undertake any additional fertilization

  and, with regard to both treated sewage sludge and its own soil, obtain quantitative analyzes concerning the cultivation or

  succession of cultures that he envisages.

  Of course, in the context of the invention, it is also possible not to use the maximum permissible spreading amount legally (for example 5 t MS / ha in 3 years), that is to say apply smaller amounts of sewage sludge when it contains a quantity of sewage sludge

  active substances which corresponds exactly to the deficit in active substances.

  Moreover, in the context of the invention, it is not absolutely necessary to

  unlike the state of the art, to use sewage sludge which already contains in itself as much of the nutrients or amounts of nutrients as possible, since the spectrum of sewage sludge can be adjusted at will according to

  the invention and that it is also possible to use sludge with no load.

  The concept of the invention therefore also takes into account the load

  cleansing mud of nutrients. Because the sludge

  Since the feedstock from different purification plants have a constant but different nutrient composition, it is possible according to the invention to obtain additional optimization by associating particularly suitable sewage sludge with particular sols. This association can be based on individual nutrients as well as on the nutrient spectrum, and it is particularly favorable to use as initial substrates sludge that is as close as possible to the soil fertilization requirements. question as to the type and quantity of nutrients or for which the quantity of chemicals or fertilizers, particularly chemicals, nutrients, nutrient mixtures, fertilizers or expensive fertilizer it is necessary to use is the lowest possible, compared to the specific needs of the soil concerned. The sewage sludge according to the invention is obtained by incorporating the amounts of main nutrients and / or trace amounts that it is necessary to add. These quantities can be introduced into fresh sludge, wet sludge, pre-dehydrated sewage sludge or even into sewage sludge already completely dehydrated or dried. If necessary, it is possible to carry out dehydration. When the amount of nutrients resulting from the difference between the fertilizer requirements and the nutrient loading of the sludge is introduced into the sludge that is

  dehydration, it is advantageous to take into account the

  loss of nutrients that occurs by extraction during dehydration. Thus, the process for the preparation of sewage sludge according to the invention is characterized by the incorporation of the additional quantities or of the necessary inputs of main and / or trace nutrients (a) into fresh sludge or wet sludge which is then subjected to dehydration to the desired solids content, preferably from about 25 to 50% by weight, possibly taking into account loss of nutrients by extraction during dehydration, or (b ) in pre-dehydrated or dried sewage sludge which is then subjected, if necessary, to additional dehydration to

  desired dry matter, preferably from about 25 to 50% by weight.

  The process according to the invention is advantageously characterized by incorporating the necessary additional quantities of nutrients

  main and / or trace elements.

  (a) in the form of corresponding chemical compounds, preferably of commercial chemical compounds or mixtures of nutritive substances

  possibly with the additional addition of organic fertilizer

  and / or (b) in the form of liquid manure or slurry and / or (c) in the form of waste and solid organic residual substances, in particular decomposed manure, animal excrement, in particular

  poultry droppings, and / or composts.

  As additives for the preparation of sewage sludge according to the invention, there is the set of nutrients and constituents of known nutrients, in particular the nutrients and constituents

  of commercially available nutrients.

  Thus, in the context of the invention, it is possible to incorporate in the sewage sludge used as a substrate, depending on the spectrum of requirements, both already prepared mixtures of nutrients or fertilizers and partial mixtures. corresponding or individual substances. Corresponding compounds of the main and trace nutrients

  are known to those skilled in the art and commercially available.

  In addition to the addition or addition of chemical compounds to the used sewage sludge, nutrient enrichment or nutrient optimization can also be carried out within the scope of the invention. addition of slurry or liquid manure or addition of organic waste and solid residual substances. Such suitable residual substances are, for example, decomposed manure, poultry excrement and composts of any origin. Because the addition of slurry, liquid manure or solid organic wastes and residuals does not permit any precise adjustment of the type and quantity of all the individual constituents of the nutrients, when these sources of nutrients are used. nutrients, the corresponding deficits in nutrients are

  adding corresponding chemical compounds.

  The use of these nutrient sources also offers other possibilities for optimizing the use of nutrient carriers which also have the advantage of being particularly economical and practically available in any quantity. This is also a contribution to solving the problem of eliminating excrement

  animals in large-scale livestock facilities.

  The incorporation of nutrients, nutrient mixtures or the corresponding natural products such as slurry, liquid manure or compost can be accomplished by means of common mixing processes and customary mixing devices which are familiar to humans of career. To do this, it is possible to add the nutrients in the form of individual constituents or in the form of mixtures, prepared in advance, of several constituents or all the constituents. In this case, it is particularly advantageous to implement a computer-controlled embodiment because substantially each sewage sludge according to the invention is in a certain way "cut to measure" with regard to the source of sewage sludge and the spreading surface so that during the optimization of the nutrients it is necessary to associate with each other and to process variable combinations of data which are very numerous and which vary according to

cases.

  The nutrient levels of slurry, liquid manure and solid organic wastes such as decomposed manure, poultry excrement, composts and the like are familiar to those skilled in the art and are determined

  they also advantageously by an analysis.

  In the case of the use of slurry or manure, the sewage sludge used as raw material is soaked or impregnated with liquid product and then advantageously subjected to dehydration which may be operated in any appropriate manner and which may be combined also to normal dewatering of sludge. In principle, however, it is also possible in the context of the invention to spread products based on semi-liquid purification sludges or corresponding suspensions. For example, in addition to the materials mentioned above, roasted horn flour, bone meal, castor flour, peat and peat products and

  garbage products of appropriate composition.

  The addition of chemical compounds or mixtures of compounds

  Chemicals can be accomplished using such products in solid form. How-

  In the context of the invention, it is also possible to use nutrients or nutrient mixtures in the form of solutions or

  dispersions, in which case a subsequent drying is carried out if necessary.

  In the context of the present invention, it may also be favorable to use some or all of the main nutrients or in the form of

  traces mixed with a lime product acting as a conditioning agent.

  for sewage sludge, in particular quicklime, hydrate

lime or milk of lime.

  It is also preferable for the sewage sludge according to the invention to be sanitized, that is to say subjected to a chemical and / or thermal disinfection treatment, since such treatment makes it possible to exclude the risks of contamination of the soil. treaty. This treatment of sewage sludge can take place before or after

  the addition of nutrients.

  The invention also relates to mixtures of nutrients which are intended to be incorporated into sewage sludge, in particular for the preparation of sewage sludge according to the invention. These nutrient mixtures are mixtures of two or more constituents which correspond to nutrients which are selected from (a) the main nutrients N, CaO, MgO, K20, P205 and S and (b) nutrients to the trace state B, Cu, Fe, Zn, Na, Mn, Mo and CI, the proportions of the nutrients in the mixtures being adjusted in such a way that the amount added to the sewage sludge and the corresponding nutrients contained in the sewage sludge used gives the nutrient levels that correspond to the needs

  in soil fertilization that needs to be treated. These mixtures are therefore preferably

  also optimized in a specific way for soil and sewage sludge, taking into account the possible implementation of multiple spreading. Nutrient mixtures may also contain additions of non-essential nutrients such as Co, Al, Si. These nutrient mixtures may also be in the form of solid substances or in the form of solutions or dispersions.

  containing one or more nutrients.

  The invention also encompasses the use of these mixtures of

  nutrients for the preparation of the corresponding sewage sludge.

  According to a preferred variant of the process for preparing the optimized sewage sludge with regard to the nutritive substances according to the invention, the following steps are carried out: () determination of the fertilization requirements of the soil to be fertilized with the sludge from the soil analysis data, taking into account the type of crop envisaged or the succession of crops envisaged during a predetermined period, in particular the duration after which a new fertilization with sewage sludge is possible; (II) Determination of the nutrient load of sewage sludge to be used from the sewage sludge analysis data, taking into account the expected amount of application and the duration defined in (I) ); (III) determination, for all the nutrients considered, of the difference between the fertilizer requirements and the nutrient load of the sewage sludge to be used and the incorporation into the sewage sludge of the quantities of the main nutrients

  and / or trace amounts that correspond to this difference.

  In the case of the use of zero-load sludge, such as that which occurs, for example, in the treatment of waste water from paper mills, dairies, etc., all the nutrients corresponding to the fertilization requirements are added. This presents a particular advantage of the invention, because, until now, sludge with no load posed particular problems of valorization, precisely as regards the spreading on agricultural useful surfaces. Other features and advantages of the invention will become more apparent

  in the following detailed description of exemplary embodiments relating to

  sewage sludge according to the invention and the determination of the type and

  quantity of nutrient additions during their preparation.

  As sludge, dewatered sludge, conditioned with lime, having a solids content of about 35% by weight was used. The following tables of Examples 1 to 3 include data from soil analysis and sewage sludge analysis as well as nutrient quantities corresponding to soil fertilization requirements, i.e. the compositions of the sewage sludge according to the invention and the amounts of application of the corresponding nutritive substances, the nutrient content of the sewage sludge and the additions or contributions relating to the maximum permissible spraying amount of 5 t MS / ha. Examples 1 to 3 relate to sewage sludge optimized for nutrients, which are optimized in a specific soil way for a given crop type and for a given crop succession, taking into account the substances contained

in the sewage sludge.

Example 1

  Analysis of the Addition Analysis incorporated into Quantity of

  soil sewage sludge sewage sludge on the field (100 mg / kg) (kg / ha) (kg / ha) (kg / ha) CaO - 300 2200 2,500 MgO 7.2 30 40 70

K20 15.2 20 180 200

P205 20.4 250 - 250

B 18.4 20 - 20

S, 15.0 - 15

Mn 10.2 3 37 40

Example 2

  Analysis of the Addition Analysis incorporated into Quantity of

  soil sewage sludge sewage sludge on the field (100 mg / kg) (kg / ha) (kg / ha) (kgtha) CaO - 400 1000 1400 MgO 10.3 20 30 50

K20 20.1 40 160 200

P205 25.4 200 - 200

B 5.2 20 - 20

S - 60 - 60

Mn 2.0 3 40 43

Example 3

  Analysis of the Addition Analysis incorporated into Quantity of

  soil sewage sludge sewage sludge on the field (100 mg / kg) (kg / ha) c (kg / ha) (kg / ha) CaO - 400 1400 1800 MgO 15.8 20 -

K20 38.2 40 - 40

P205 14.1 200 - 200

B 1.4 20 - 20

S 2.0 60 - 60

  Mn - 3 - 3 Cu 1,0 1,5 10 11,5 The incorporated additions represent mixtures of substances

nutrients according to the invention.

  Examples 1 to 3 thus illustrate the optimization according to the invention of the nutrients of sewage sludge which is made in a specific manner.

soil and culture.

  EXAMPLE 4 A pre-dehydrated sewage sludge having a solids content of about 25% by weight was added per m3 of about 150 kg of a mixture which contained about 140 kg of CaO, 8 kg of K20 and 2 kg. from Mn. The nutrient-enriched mud thus obtained can be applied in one

  amount of 5 t DM / ha.3 years applied to appropriate surfaces corresponding to

ponding.

Example

  A pre-dehydrated filter cake from a water softening plant having a solids content of about 50% by weight, an inorganic solids content of about 40% by weight and a content of organic dry matter of about 10% by mass, which contained

  traces of Mn and Fe, has been combined with lime and magnesium compounds.

  sium and potassium by introduction of 300 kg of CaO, 300 kg of MgO and 300 kg of K2, O. The already spreadable mixture in this case can be applied in a quantity

  spreading rate of 5 t MS / ha. 3 years on corresponding appropriate surfaces.

  The present invention also encompasses methods for providing nutrients or fertilizing agriculturally and horticulturally useful surfaces or other cultivation surfaces by spreading sewage sludge, which

  are characterized by the spreading of sewage sludge according to the invention and by the use of

  the use of sewage sludge according to the invention for the supply of nutrients or manure to agriculturally and horticulturally useful surfaces and

to other growing surfaces.

  The concept of the invention has the following advantages: 1. The provision of sewage sludge enriched in nutrients and in particular optimized for nutrients can significantly promote the reception of sewage sludge in agriculture and agriculture. the use of such sewage sludge is extremely favorable from the point of view of organization and from the economic point of view, especially as no fertilizer costs are chargeable of the user. 2. In the case of sewage sludge according to the invention which can be spread by means of special vehicles which preserve the soil, it is not necessary for other vehicles to travel through the treated soil by means of the optimized spreading of the soil. nutrients, which avoids undesirable soil compaction. 3. The sewage sludge according to the invention can be used not only in agriculture and horticulture, but also for cultivation and cultivation.

landscape architecture.

  4. The sewage sludge according to the invention has a total composition of

  quantitatively defined by soil analysis and mud analysis

  used, even with regard to the heavy metal content.

  This is an advantage over the separate use of fertilizer after traditional sewage sludge application, as in many cases conventional fertilizers may have levels of heavy metals and other harmful substances that are excessively in addition not determined by the analysis. According to the invention, such soil pollution is

avoided in a safe way.

  5. - The sewage sludge according to the invention also allow manure on

  several years without the need to apply fertilizer separately.

  6. The incineration of sewage sludge, which is extremely undesirable from an ecological and economic point of view, is superfluous, which is also an advantage with regard to the reduced CO2 emissions from the corresponding incineration plants and the problem of the setting

ash discharge.

  7. In the context of the invention, it is possible to advantageously recover waste and residual organic liquid and solid substances. These residual substances are used in the context of the invention as valuable means for the targeted balancing of nutrients

in soils.

  8. The concept of the invention allows specific soil optimization of nutrients for useful surfaces or culture surfaces of any size, even for small plots. This makes it possible to avoid an unnecessary or involuntary excessive manuring of specific surfaces, which could occur in the state of the art during a new, separate manure.

  which is favorable from the ecological and economic point of view.

  9. The invention opens a way towards the optimal use of sewage sludge in the form of precious fertilizers and thus contributes to saving

unnecessary discharge surfaces.

  10. The use of the nutrient load of sewage sludge used preserves the natural resources of these substances

  nutrients or corresponding precursors.

  11. The invention allows for the first time the agricultural use of zero-load sludge, because in the context of the invention, it is possible even to the limit to use sludge which, apart from the organic biomass, contain virtually no nutrients in the same way as sewage sludge containing nutrients. 12. The specific costs related to the recovery according to the invention of sewage sludge are approximately 2 to 4 times lower than those of the others.

  solutions constituted by dumping or incineration.

  13. The use of previously weighed and pre-mixed ingredient mixtures for the addition of nutrients, adjusted to each used sludge

  and corresponding soil, allows a relatively uniform unit

  simple operation, for example at the level of the purification plant.

  Thus, as the foregoing shows, the concept of the invention

  has many technical, economic and ecological advantages.

Claims (27)

  1. Sewage sludge intended for spreading on agricultural and horticultural surfaces or on other growing surfaces, characterized in that they contain added nutrients which are selected from among C, N, P, Na, K, Ca, Mg, Fe, Mn, Zn, Cu, Co, Mo, B, Si, Al, O, Cl and S. 2. Sewage sludge according to claim 1, characterized in that they have the following contents of main nutrients, each reported to the dry mass (DM) of the sewage sludge used: (g / kg of DM) Total N: <300, preferably <50, more preferably <20 CaO -: <800, preferably <500 MgO: <90, preferably <30, more preferably <15 K20: <90, preferably <50 P205: <160, preferably <80, more preferably <50 S: <30, preferably <3.0.   3. Sewage sludge according to claim 1 or 2, characterized in that they have the following contents of trace nutrients, each reported to the dry mass (DM) of the sewage sludge used: (g / kg of MS) B: <16, preferably <1.1, more preferably <0.1 Cu: <12, preferably <0.8, more preferably <0.4 Fe: <30, preferably <3.0 Zn: <30, preferably <2.5, more preferably Na: <30, preferably <0.3 Mn: <36, preferably <0.5, more preferably < 0.25 Mo: <12, preferably <0.15, more preferably <0.01 Cl: <1, preferably <0.3.   4. Sewage sludge according to any one of claims 1 to 3,   characterized in that the sewage sludge component comes from sewage treatment plants for the treatment of domestic wastewater, communal sewage or wastewater with low substance loadings. harmful analog.   5. Sewage sludge according to any one of claims 1 to 4,   characterized in that they are in the form of wet sewage sludge, dewatered sewage sludge and / or dried sewage sludge.   6. Sewage sludge according to any one of claims 1 to 5,   characterized in that they have a solids content of 25 to 95% by weight and preferably 25 to 35% by weight or preferably 35 to 50% by weight, each referred to the dry mass (DM ) sewage sludge used.   7. Sewage sludge according to any one of claims 1 to 6,   characterized in that their contents of one or more main nutrients and / or trace amounts are adjusted in such a way that the amounts of the corresponding nutrients which are provided in a single application of a spreading quantity sewage sludge data correspond approximately or exactly to the fertilization requirements of the soil that needs to be   fertilized with the sewage sludge for a predetermined duration.   8. Sewage sludge according to any one of claims 1 to 6,   characterized in that their contents of one or more main nutrients and / or trace amounts are adjusted in such a way that the sum of the amounts of the corresponding nutrients which are provided in a multiple application for a predetermined period of time or during multiple spreading at predetermined intervals and in each case for a predetermined spreading amount of the sewage sludge corresponds approximately or exactly to the fertilization requirements of the soil to be fertilized by the sewage sludge for the duration predetermined period or during the period corresponding to intervals between spreads.   9. Sewage sludge according to claims 7 or 8, characterized in   what the type of crop plants planned or the succession of crops planned during the predetermined period are taken into account for fertilization requirements   soil which serve as a basis for the amounts of nutrients.   10. Sewage sludge according to any one of claims 7 to 9,   characterized in that the fertilization requirements which serve as a basis for the amounts of nutrients are referred to an effective fertilizer for several years.   11. Sewage sludge according to any one of claims 7 to   characterized in that their contents of one or more main nutrients and / or trace amounts are adjusted in such a way that the quantities of the relevant nutrients which are supplied with a given amount of sewage sludge application applied once for a predetermined time, preferably 3 years, preferably a maximum spreading amount of 5 t MS / ha, correspond to the soil fertilization   must be fertilized with the sludge during this period.   12. Sewage sludge according to any one of claims 1 to   11, characterized in that they can be obtained by incorporating the necessary amounts of inputs into main nutrients and / or trace amounts (a) - into fresh sludge or wet sludge which then undergoes dehydration up to at the desired solids content, preferably from 25 to 50% by weight, possibly taking into account loss of nutrients by extraction during dehydration, or (b) in prehydrated or dried sewage sludge which subject, if necessary, to additional dehydration up to the   desired dryness, preferably from 25 to 50% by weight.   13. Sewage sludge according to claim 12, characterized in that they can be obtained by incorporating the quantities of inputs required in main nutrients and / or in trace amounts, (a) in the form of chemical compounds corresponding, preferably of commercial chemical compounds or mixtures of nutrients   possibly with the additional addition of organic fertilizer   and / or (b) in the form of manure or slurry and / or (c) in the form of waste and solid organic   particular decomposed manure, animal excrement and / or composts.   14. Sewage sludge according to claim 12 or 13, characterized in that they can be obtained by the use of the amounts of inputs required for main nutrients and / or trace amounts in the form of individual constituents. , in particular individual chemical compounds or single fertilizers, or in the form of partial mixtures or mixtures of all the necessary constituents, in particular in the form of mixtures composed of   main nutrients and / or trace nutrients.   15. Sewage sludge according to any one of claims 12 to   14, characterized in that they can be obtained by using the main or trace nutrients in solid form or in the form of solutions or dispersions.   16. Sewage sludge according to any one of claims 12 to   characterized in that they can be obtained by using some or all of the main or trace nutrients in admixture with a lime product serving as a conditioning agent for sludge. purification, in particular in mixture with quicklime, hydrate of lime or jade of lime.   17. Sewage sludge according to any one of claims 1 to   16, characterized in that they are sanitized or disinfected chemically and / or thermally. 18. Mixtures of nutrients for incorporation into sewage sludge, in particular for the preparation of sewage sludge according to   any of claims 1 to 17, characterized in that they comprise at least   minus two constituents that correspond to nutrients that are selected from (a) the main nutrients N, CaO, MgO, K20, P205 and S and (b) the trace nutrients B, Cu, Fe, Zn, Na, Mn, Mo and CI, the proportions of the nutrients in the mixtures being adjusted to such   as a result, for the quantity added to the sewage sludge in combination with   with the corresponding nutrients contained in the   used sewage sludge, the nutrient levels according to the   cation 2 or 3 or according to claim 7, 8 or 11.   Nutrient mixtures according to Claim 18, characterized in that they are in the form of solid substances or in the form of solutions or dispersions.   20. Process for the preparation of sewage sludge according to one of   any of claims 1 to 17, characterized by the incorporation of the quantities   necessary nutrient and / or trace element inputs (a) in fresh sludge or wet sludge which is then dehydrated to the desired dry matter content, preferably 25 to 50% by weight, possibly taking into account nutrient loss by extraction during dehydration, or (b) in prehydrated or dried sewage sludge, which is then subjected, if necessary, to additional dehydration up to the level of   in desired dry matter, preferably from 25 to 50% by weight.   21. A process according to claim 20, characterized by the use of the amounts of inputs required in main nutrients and / or trace amounts (a) in the form of corresponding chemical compounds, preferably of commercial chemical compounds. or mixtures of nutrients   possibly with the additional addition of organic fertilizer   and / or (b) in the form of manure or slurry and / or (c) in the form of solid organic wastes and residues, in particular decomposed manure, poultry excrement and / or composts. 22. Process according to claim 20 or 21 for the preparation of optimized sewage sludge with regard to nutrients according to   any one of claims 7 to 11, characterized by the following steps:   (t) determination of the fertilization requirements of the soil to be fertilized with the sludge from the soil analysis data, taking into account the type of crop envisaged or the succession of crops envisaged for a predetermined period, in particular the duration after which a new fertilization with sewage sludge is possible; (I1) Determination of the nutrient load of the sewage sludge to be used from the sewage sludge analysis data, taking into account the expected amount of application and the duration defined in (1) ); (III) determination, for all the nutrients considered, of the difference between the fertilizer requirements and the nutrient load of the sewage sludge to be used and the incorporation into the sewage sludge of the quantities of the main nutrients   and / or trace amounts that correspond to this difference.   23. Process according to any one of Claims 20 to 22,   characterized by the use of zero-load sludge as sludge.   24. A method according to any one of claims 20 to 23, characterized   the use of the nutrient mixtures according to the claim 18 or 19.   25. Process according to any one of claims 20, 21, 22 and 24,   characterized by the use of sewage sludge with a nutrient load which, in relation to the type and / or amount of nutrients, is closest to the corresponding soil fertilization requirements or requires the least use of nutrients; chemicals, nutrients, blends of nutrients or fertilizers.   26. Process for supplying nutrients or manure to agricultural and horticultural surfaces or other cultivation surfaces by spreading sewage sludge, characterized by the application of sewage sludge according to one of the following:   any of claims 1 to 17.   27. Use of sewage sludge according to any one of   claims 1 to 17 for the supply of nutrients or manure to   agricultural and horticultural surfaces and other growing areas.