AU1729701A - A method and system for treatment of animal waste - Google Patents

Description

WO 01/42171 PCT/ILOO/00816 A METHOD AND SYSTEM FOR TREATMENT OF ANIMAL WASTE FIELD OF THE INVENTION This invention relates to the field of waste management and particularly to a method for the treatment of animal manure, including controlling malodor associated with same waste, to compositions useful for such treatment as well as to the uses of the products obtained by said treatment. BACKGROUND OF THE INVENTION Animal waster including excreta, food remains, and animal bedding typically accumulate in a husbandry of commercial animal production. Such accumulated substances need to be properly managed. Animal manure, particularly its odor and excessive nutrient concentrations, are a serious and a growing problem, especially in the field of commercial animal husbandry. There is a global need for the development and improvement of waste management and odor control facilities and method associated with animal husbandry, e.g. in the beef cattle industry, dairy industry, poultry industry and in swine industry.

WO 01/42171 PCT/ILOO/00816 -2 Manure can be handled as a liquid, a semi-solid or a solid. The amount of bedding and dilution water influences manure characteristics. These characteristics affect the type of manure management system suitable for waste treatment. Typically, solid manure is a combination of bedding and feces. Semi-solid manure is a combination of feces, urine and some bedding and no extra liquid is added, while liquid manure has water added to form a floatable mixture. Many factors have to be considered when choosing the type of manure management system for a specific animal production operation. These include: the livestock type (cattle, hogs, poultry), the age and size of animal, the feed required, the housing system, the bedding required or available, the cropping practice of the area, proximity to waterways, proximity to neighboring residential areas and the personal preference of the livestock grower. One of the most common and basic manure treatment facility is the lagoon system, which may be used regardless of the animal managed in the operation. Lagoons originated as a means of storing and conserving fertilizer nutrients from the waste of animals up until the time it was applied directly to the soil. Lagoons act as digesters in which two major types of bacteria decompose organic matter into liquids and sludge: anaerobic bacteria, typically present in the intestinal tract of warm blooded animals and are active under WO 01/42171 PCT/ILOO/00816 -3 oxygen-free conditions; and aerobic bacteria which are active only in the presence of dissolved oxygen, resulting either from diffusion across the water surface of the lagoon, or as a result of photosynthesis by algae. Lagoon systems, however, yield a loss of nutrient value. Further, as malodors are prevalent in most lagoon systems, frequent sludge removal is required, especially if the lagoon is undersized for the operation and there is a need for water level control and mechanical aeration systems to keep the lagoon in operation. Such removal may increase the cost of the operation. The malodors released from the manure present a major environmental problem. Odor in livestock operations is the direct result of the decay of organic materials, be it feces or feed products and the resulting high concentrations of ammonia, hydrogen sulfide, carbon dioxide, trace gases, volatile organic compounds, methane dust and some pathogens. The odor may be treated by ventilation, either by natural wind-propelled ventilation, by mechanical ventilation using fans, ventilation, tunnels, etc. Alternatively, the released odor may be reduced by the use of biofilters or biomass filters, or by covering the storage structures (e.g., lagoon) with either high density polyethylene materials or straw, corn stalks, etc., the latter having the limitation that they become soaked with water and thus sink, thereby contributing to manure solid and odor problems in the storage tank.

WO 01/42171 PCT/ILOO/00816 -4 US patent 3,884,804 deals with a method of treating animal wastes to reduce odors produced by the decomposition of the organic materials in the animal wastes. The following systems were discussed: 1. Contacegon particles, comprising solid catalyst particles having surface portions which are wetproofed by treatment with a hydrophobic material , are floated on the surface of a watery mass containing the animal wastes. The Contacogen particles promote the oxidation by air of the odoriferous compounds produced by the degenerative breakdown of the animal wastes. The Contacogen particles are solid catalyst particles which have been treated with a hydrophobic agents selected from the group consisting of polytetrafluoroethylene, silicon resins and silica colloids made hydrophobic by surface conversion to silicone. The catalyst particles may be any substance presenting a large specific surface area which has the property of catalyzing the oxidation by air of the odoriferous compounds produced by the degenerative breakdown of animal wastes. Activation carbon is such a catalyst. 2. Floating on the surface of a watery mass of animal wastes solid catalyst particles selected from the group consisting of carbon and activated carbon particles having surface portions of a hydrophobic material which forms a discontinuous film thereon. The hydrophobic materials are selected from the group described above. The size of carbon particles may vary from about 10 micron (for a powder) to relatively large size granules (about 1 cm).

WO 01/42171 PCT/ILOO/00816 -5 It was surprisingly found that hydrophobic particles of a smaller size than 10 microns are highly effective in treatment of liquid and semi-solid animal manure. More specifically, floatable hydrophobic particles having a diameter of less than 1pjm in association with floatable, high porous particles, having both hydrophilic and hydrophobic groups play an important role in a highly effective management of animal waste. More specifically, in accordance with the present invention, a new distinct surface layer is formed (hereinafter referred to as the "interface layer") over the upper face of the animal waste pool. Same interface layer has multiple functions, based on its chemical composition and physical structure, and provides changes in the properties and composition of the upper pool layers. The interface layer may contain different components, in accordance with the desired function to be achieved. Said components are selected from the group comprising: (a) floatable, substantially hydrophobic nano-range particles having a diameter of less than 100 nm, and preferably, 2-40nm (hereinafter referred to as "component A"). Such particles may be, for example, modified silica ( for example, alkyl-silica), modified minerals (such as, alkyl-mineral materials), and others. (b) floatable, high porous (over 50% of the material consisting of pores) particles having both hydrophobic and hydrophilic groups (hereinafter referred to as "component B"). Such materials may be for example, WO 01/42171 PCT/ILOO/00816 -6 perlite, claydite, plant-material residues (wood pieces, wood pulp, sawdust, straw, etc.). Same particles, having a diameter of >1lm, may optionally be associated with (1) said substantially hydrophobic nano-range particles; with or without (2) substantially hydrophilic nano-range particles (hereinafter referred to as "component C") having a diameter of less than 100 nm, and preferably, 2-40nm. Such particles may be, for example, silica, alumina, and other oxygen-containing minerals; and/or (3) photo-catalysts capable of decomposing organic material and malodors; and/or (4) aerobic bacteria capable of degrading organic waste materials. (c) active carbon particles in association with component A and/or component B. More specifically, component A represents nano-size, non-porous, mechanically rigid and highly dispersable particles whereas component B represents porous, micron-to-cm size, mechanically brittle particles. Furthermore, a particle of component A has a huge outer convex surface per volume or weight, whereas a particle of component B has a huge inner concave surface due to the pores and holes. Particles of component C have similar physical and mechanical properties suach as particles of component

A.

WO 01/42171 PCT/IL00/00816 -7 In spite of the above differentiation between components A and B, both particles may be of the same or different materials and they may be subjected to the same or different pre-treatment procedures for rendering hydrophobic and/or hydrophilic properties. SUMMARY OF INVENTION It is an object of present invention to provide a novel system and method for the treatment of liquid and semi-solid animal waste. The animal waste includes feces, typically also urine, and at times, also animals bedding material and food remains. It is a further object of present invention to provide a treatment means of same animal waste in a receptacle suitable for collecting such waste. The receptacle may be a receptacle which directly receives the animal waste preferably positioned underneath the animal growing facility. Alternatively, the receptacle may be a reservoir situated outside the animal growing facility to which the animal waste is transferred through pipes or channels, by the use gravity caused flow or various pumping arrangements, etc. the receptacle containing the animal waste will be referred to herein as the "animal waste pool". It is yet an another object of present invention to prevent, reduce and/or remove malodors typically associated with such animal wastes. The present WO 01/42171 PCT/ILOO/00816 -8 invention provides, inter alia, a method and system for managing waste associated with animal production, in which the organic substances and malodor resulting therefrom are decomposed and/or adsorbed by a particular porous particulate material of the invention. Consequently, a further object of present invention is the provide of fertilizer compositions formed following a treatment of animal waste in accordance with the present invention. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS In accordance with present invention, an interface layer is formed over the upper face of the animal waste pool. This interface layer comprises particulate matter which acts in changing the properties and composition of the upper pool layer by virtue of the interface layer functional properties. Such functional properties include one or more of the following: (1) ability to adsorb organic matter present in the pool; (2) ability to catalytically act in degrading volatile malodorous substances; (3) the ability to form a barrier for malodor transfer from the pool to the surrounding atmosphere while keep maintaining water evaporation capability or, if desirable, (4) the ability to biologically degrade organic waste through bacteria which are contained within the interface layer. Consequently, the interface layer may demonstrate the following multiple functions: WO 01/42171 PCT/ILOO/00816 -9 1. An interface layer consisting of component A: Component A forms a semi-impermeable membranous barrier preventing malodor transfer from the waste pool to the external atmosphere. Such a barrier allows transfer of relatively small molecules (such as, for example, water) from the pool to the surrounding atmosphere. In case of stabile interface layer (consisting of, for example, methyl-silica particles) it may remain efficient in controlling odor for about a week before it loses its mechanical stability. Whenever labile interface layer is formed (consisting of, for example, n-butyl-silica particles) it may remain efficient for a shorter time. However, the last case may fit better the procedures involved in controlling odors released from continuously slow moving or flowing waste pools. 2. An interface layer consisting of various combinations of component A and component B: The process for controlling malodors associated with liquid or semi-solid animal waste may result in providing useful fertilizers as by-products. Several possibilities exist, among them are: (a) Providing an organic-based fertilizer: (I) An interface comprising a combination of component A (for example, methyl- silica) and component B (for example, high porosive perlite) WO 01/42171 PCT/ILOO/00816 - 10 and optionally component C (for example, silica) to form an interface layer in which a certain amount of nano-particles (components A and optionally component C) are adsorbed onto the surface of porosive particles (component B) which serve as carriers. Such an interface layer, containing an appropriate amount of nano-particles, functions as a semi-permeable membrane allowing the release of water vapors but prevent release of other gases thus maintaining the malodors within the pool isolated from the surrounding atmosphere. Water molecules of the upper layer which are evaporated (in a sublimation-like process) into the surrounding atmosphere, continuously substituted by other water molecules coming from the liquid phase. Furthermore, the addition of nano-range hydrophilic particles (component C) to a combined particulate combination of components A and B provides an improved semi-permeable interface layer due to the wet of nano-range hydrophilic particles with the evaporated water to form a "wet-filter". Such a treatment of the waste pool will result in a partial or complete adsorption of organic material onto the interface layer. Consequently, the interface layer, or its residual, containing the adsorbed organic substance may be used, following its removal from the pool, as a carrier for prolonged release organic ingredients and/or nutrients useful in fertilization of various crops.

WO 01/42171 PCT/ILOO/00816 - 11 It should be pointed out, that an interface layer that consists of combination of component A and component B, and optionally component C retains simultaneously hydrophobic character (provided by components A and B) and hydrophilic character (provided by component B and optionally by component C). The combination of components A and B , and optionally C, is dependable on and associated with physical forces. For example, the nano-range substantially hydrophobic particles may be adsorbed, attached, or attracted to component B particles by means of electrostatic forces, such as Van-Der-Vaals forces. When particles of component C are involoved, additional forces, such as hydrogen bonds, may be involved, as well. However, it should be emphasized that the formation and function of the interface layer is dependable upon the enormous particle's surface area per volume, or weight (specific area). Thus, the surface of 1 gram of nano-range particles has a surface area of 200 square meter and may reach twice this number. Consequently, a combination of porous B particls with nano-range particles (such as, for example, methyl-silica and perlite) contains a very high ratio of surface area to volume, forms an equivalent interface layer that functions similarly to the one described above. It should be further emphasized, that it is desirable to wet by aqueous solution of glycerine (or of a glycerine-like material), the floatable WO 01/42171 PCT/ILOO/00816 - 12 particulate material, consisting of particles of component B adsorbing nano-range particles, to prevent the removal of powdery nano-range particles while spreading the particulate material over the waste pool. Such a wet treatment may include sprinkling of the particulate material using solution drops, before use or during manufacturing process, followed by hermetic packaging. (II) An interface comprising particles of component A in association with particles of component B, having photo-catalyst (for example, TiO 2 ) impregnated or adsorbed, either onto surface of particles of component A and/or surface of particles of component B. Such an interface layer, that may optionally contain particles of component C, may consist of catalyst-bound nano-range substantially hydrophobic particles (for example methyl-silica) adsorbed onto the surface of particles of component B and/or catalyst-bound particles of component B (for example, a high porous perlite) adsorbing onto particles of component A, and/or catalyst-bound particles of component A adsorbed onto surface of catalyst-bound particles of component B. The photo-catalytic compound maintains the decomposition of malodors evolved and/or reached to surface of the pool. Such a treatment of the waste pool will result in a partial or complete adsorption of organic material onto the interface layer. Consequently, the interface layer, or its residual, containing the adsorbed organic substance may be used, WO 01/42171 PCT/ILOO/00816 - 13 following its removal from the pool, as a carrier for prolonged release organic ingredients and/or nutrients useful in fertilization of various crops. (b) Providing an inorganic -based fertilizer: A layer interface may comprise a combination of a proper amount of component A, component B (containing an aerobic bacteria) and optionally component C. Such an interface (containing, for example, methyl silica adsorbed onto the surface of a high porous perlite in which aerobic bacteria are implemented within its pores, and optionally paticles of component C) functions as a semi-permeable membrane allowing the release of water vapors while maintaining the malodors within the pool isolated from the surrounding atmosphere. Such a treatment of the waste pool will result in a partial or complete adsorption of inorganic residual material remaining following the bacterial decomposition of organic substances accumulated onto the interface layer. Consequently, the interface layer, or its residual, containing the adsorbed inorganic materials may be used, following its removal from the pool, as a carrier for prolonged release inorganic ingredients and/or nutrients useful in fertilization of various crops. It should be pointed out that an interface layer comprising a combination of component A, in association with a photo-catalyst, and WO 01/42171 PCT/ILOO/00816 - 14 component B containing aerobic bacteria, is well within the scope of present invention, as well. As a matter of principle, it should be emphasized that adding particles of component C (nano-range hydrophilic particles) to a combination of particles of components A and particles of component B will result in adsorbance of hydrophilic particles of component C onto the surface and within the pores of particles of component B. The combination of these three components, provides additional advantages, such as an increase of stability of the interface layer against outside mechanical disturbance (winds, waves etc). Furthermore, the presense of hydrophillic particles on the surface and within pores of particles of component B makes during the time the particles heavier due to absorbing water from the waste pool and thus enhances the gases anti-release pressure, resulted in reducing release of malodors to the surrounding atmosphere. An insertion of active carbon particles as a component (in addition to either component A and/or component B, with or without component C) in the interface layer provides some advantages such as, an increase in gases adsorption (including malodors), in ionic materials adsorption, resulting in removing an excess amount (which may be toxic) of N- and/or P- and/or K - based inorganic compounds. Furthermore, black particles intend to adsorb sunlight and consequently to heat the pool, resulting in enhancing WO 01/42171 PCT/ILOO/00816 - 15 the biological degradation processes. The particulate material which forms an interface layer may be pre-treated in a manner so as to enable it to float over the surface of the liquid for a period of time. Such a treatment may include sintering (forming closed gas/air filled pores which render the particulate material floatable); chemical modification of the particulate material to make it carries the proper proportion of hydrophobic and/or hydrophilic groups; binding catalytic compounds to the particulate material; adsorbing particulate materials of various sizes to one another; associating (impregnating, adsorbing etc.) the particulate material with bacteria, typically aerobic bacteria, which then colonize the pores in the material (pores are considered here as free spaces not only within the particles, but also as spaces between neighbor particles . It should be noted that an important requirement of the particulate material which forms the interface layer is that it has an overall specific gravity less than that of water so that it will remain afloat on the top surface of the waste pool. With some of the particulate matter used as the interface layer material, this may be a result of the porosity of the component B particles and the sintering thereof to close some of the pores to form closed air pockets. The porosity of the component B particles used in accordance with the invention is typically above 50% and preferably within the range of 70-99%.

WO 01/42171 PCT/ILOO/00816 - 16 At times, as already mentioned above, the interface layer-forming particles may be treated by chemical binding or adsorption thereto catalytic components, e.g. photo-catalysts. Examples of catalysts are heavy metal complexes or oxides, such as titanium oxide (TiO 2 ). The catalysts, if present on the particles, serve for the degradation of volatile organic matter released from the waste pool. This reduces the malodors which are typically associated with animal waste. It should be noted that silica or some minerals that have some catalytic properties by their own, may be combined with other catalytic component to yield a more pronounced effect. The invention thus provides a method for treatment of liquid or semi-solid animal waste, comprising: (a) collecting the animal waste into a receptacle, to form a liquid or semi-solid waste pool; (b) introducing onto the waste pool a floatable particulate material selected from the group comprising component A, component B, active carbon or any combination thereof, with or without catalysts and/or microorganisms, which forms an interface layer over a top surface of said pool, said interface layer having an effect on the composition of the pool's upper layer or its interaction with the overlaying atmosphere; and WO 01/42171 PCT/ILOO/00816 - 17 (c) incubating said particulate material in said pool for a time sufficient to yield said effect, while periodically, if necessary, replacing or replenishing the interface layer with new such said material. Said effect may, in accordance with one embodiment, be the prevention or reduction of malodors. For that purpose, the treatment in accordance with present invention will proceed at least for a time until the waste material solidified or otherwise change its properties to avoid malodor. In accordance with another embodiment of present invention, said effect comprises adsorption or degradation of organic matter in the upper layer. The porous hydrophobic particulate material, which partially or completely, forms the interface layer, adsorbing the organic material within its pores and subsequently removing it from the upper layer of the waste pool. This will give rise to depletion of organic material from the pool's upper layers which gives rise to some drift of organic material from lower layers to upper layers. If necessary, the interface layer may be replaced or replenished with fresh interface layer forming material, thereby retaining the capacity to continuously adsorb organic material from the pools' upper layers. The animal waste is treated to eventually obtain a particulate product useful as an organic fertilizer. Such an interface layer-fertilizer WO 01/42171 PCT/ILOO/00816 - 18 composition, which is substantially detoxified is also within the scope of the present invention. It should be noted that the particulate materials used in the formation of the interface layer are preferably nutritionally inert and valueless, and only when having adsorbed thereon organic substances may be useful for fertilization. The system of the invention may also comprise black particles as means for heating the animal waste to accelerate the waste treatment process. Additional heating means may include, for example, waste treatment facility covered by a greenhouse-like structure to obtain a greenhouse heating effect. Hydrophobic particulate material may be obtained by various procedures known in the art. The procedure employed may depend, inter alia, on the material from which the particulate material is made of. According to one embodiment, at least part of the interface forming particles consist of one or more materials selected from the group of compounds named "oxides" and/or compounds containing oxide group(s), which typically contains hydroxyl groups on their surface. The hydrogen atoms of the hydroxyl groups may be substituted by hydrophobic groups, such as -alkyl, -Si-(lower alkyl)3 and others.

WO 01/42171 PCT/ILOO/00816 - 19 According to another embodiment of the process of present invention, the covalent bonds of the hydrophobic groups are relatively stabile (for example, when the alkyl is a methyl group) and consequently, there will be no subsequent dissociation of the hydrophobic moieties from the particulate material forming the interface layer and same particulate material will continuously float at the top surface of the waste pool until being manually removed. Methylation of hydroxyl groups, is a well know procedure. In general, oxide particles, e.g. silica particles (SiO 2 ) are first heated to remove physically adsorbed water therefrom, then, the particles are reacted with a suitable reagent, such as, for example, n-butanol, Cl-Si-(CH 3

)

3 or poly-methylsiloxane at an elevated temperature, wherein the hydrophobic group (-n-butyl or -Si-(CH 3 )a) substituting the hydrogen atoms of the hydroxyl groups on the surface of the particles. The reaction duration, concentration of methylating agent and temperature employed during the reaction will determine the degree of methylation and consequently, the floatation characteristics of the particle. The binding of the hydrophobic group may, if so desired, forms a relatively unstable bond, which in the presence of water, may undergo hydrolysis to release the corresponding alcohol. For formation of a relatively unstable bond, a similar treatment may be performed, however at lower temperatures and using different reagents, such as for example, alcohol of the general formula R-OH (R represents low alkyl) to form the relatively unstable bond -Si-O-R, wherein the hydrophobic group is subsequently WO 01/42171 PCT/ILOO/00816 - 20 hydrolyzed to release the corresponding alcohol (R-OH). Consequently, the hydrolyzed particulate material may regain in time its hydrophilic nature, and as a result it may sink into the aqueous medium. Furthermore, the dissolved alcohol may inhibit any bacterial degradation (in particular, anaerobic) occurring in the anoxic areas of the liquid, thereby minimizing the conversion of the organic substances in the waste into methane gas. Such inhibition is desirable to prevent full degradation of organic substances which become adsorbed onto the particulate material, thus permitting the use of these organic material-carrying compositions, for example, as fertilizers. It should be pointed out that optionally, and when so desired, the hydrophobic groups may be bound to the hydroxyl groups by means of non-covalent binding, for example, hydrogen bonds. Such a link, or association, is within the scope of present invention, as well. It will be appreciated by the artisan that the interface layer formed at the top surface of the waste pool may contain particulate material treated by more than one of the above described prior treatments or equivalents thereof or by any other one or more treatments to render the particulate material floatable. Thus, a particle may be both sintered and carry chemically bound hydrophobic groups thereon. Further, the interface layer WO 01/42171 PCT/ILOO/00816 - 21 may comprise particulate materials having different levels of hydrophobicity. The particulate materials of the invention may be treated silica particles, treated mineral particles and/or treated plant material residues, all of which are known to contain a significant content of oxygen atoms and hydroxyl groups on their surface. Further, the particles may be of a porous hydrophobic polymer, such as hydrophobic polyesters or any other porous material which is, or may be treated to become, a floatable material. Within the scope of the present invention, mineral particles include, but are not limited thereto, silica minerals, e.g. perlites, clay minerals, e.g. bentonite and claydite or alumina minerals or any other mineral being porous and containing a significant content of oxygen. Plant material residues include, but are not limited thereto, husk straw, peat, dry stems, sawdust, etc. According to an additional embodiment of present invention, the volatile materials released from the waste pool are decomposed by a catalytic component present in the interface layer at the top surface of the waste pool. Such catalytic components are preferably photo-catalysts which are known to the person versed in the art. They include, but are not limited thereto, heavy metal complexes, such as non-poisonous complexes of Fe, Cu, Co, or Ni or metal oxides, such as TiO 2 or A1 2 0 3 . The catalytic WO 01/42171 PCT/ILOO/00816 - 22 components may be either dispersed in the interface layer or be adsorbed onto the porous particulate material. One way of adsorbing the catalytic components onto the porous particulate material is by means of electrostatic interactions. This may be accomplished by spraying the mixture of particulate material and catalytic component with a hot and dry air (optionally ionized), which gives rise to build-up of electrostatic charges onto the particle surface. The particulate material of the invention may be of various sizes ranging from nano-range particles having a diameter of less than 1pm (components A and C), preferably in the range of 2-50 nm The particulate material of the invention may be of various sizes ranging from nano-range particles having a diameter of less than 1pm, and particles having diameter larger than 1pm (component B), including particles having a diameter in the range of millimeters to several centimeters. Due to their small size the nano-range particles have a relatively greater surface area comparing to particles of component B and therefore they suppose to exhibit preferable floating capabilities. However, nano-range particles are porous-less and their very small size may result in their drawn away from the waste pool by air movement. Thus, according to the present invention it is preferable that the nano-range particles be adsorbed onto surface of floatable component B particles. The adsorption of nano-range particles onto surface of component B particles may be achieved, for example, in the WO 01/42171 PCT/ILOO/00816 - 23 manner described above in connection with the adsorption of catalytic components onto the particulate material or by any other suitable means for association of the two types of particulate materials. According to a further embodiment of the invention, the interface layer may further comprise active carbon particles (e.g. graphite, charcoal particles). Active carbon particles are known as having the capability of absorbing gases and may thus prevent, or at least reduce, the amount of noxious odors released from the waste pool. Further, as such particles are typically black, they may function to absorb sunlight and heat the pool facilitating the biological degradation process. At times, the system may comprise other or additional heat-absorbing particles, such as dark-colored rubber particles (may be prepared from used tires). Heating means with a greenhouse-like cover structure may also be used for waste pool warming. Yet further, the interface layer may comprise bacteria, preferably aerobic bacteria, carried within the pores of the component B particles for biological degradation of the organic substances in the animal waste. The bacteria are typically contained in pores having a diameter in the range from about 1 to about 50 jim, while smaller pores, having a diameter in the range of nanometers may function as trap means for the organic substances (the organic substances will be adsorbed in these traps by hydrophobic interaction). Thus, organic and inorganic materials are trapped in the bacteria-free pores.

WO 01/42171 PCT/ILOO/00816 - 24 The aerobic bacteria will lead to the partial decomposition of the organic substances which may at times be desirable. The bacteria may originate from the waste in which bacteria is inherently present or from impregnation of the particles with such bacteria prior to their introduction into the waste-containing pool. Any available suitable bacterial cultures may be used for either impregnation, adsorption or growing (followed by a dry-lyophilization process) within of the pores of the particulate material. The method of the invention may be a batch process, wherein waste is introduced into the receptacle before beginning of the treatment, or a continuous process, wherein animal waste is continuously, or periodically, added to the pool. In any case, the interface layer forming material may be replaced or replenished with new particulate material several times during the waste treatment procedure. The interface layer and its particulate material is preferably collected, optionally dried, and may then be subsequently used as prolonged-release fertilizing compositions as described above. The advantage of such fertilizer compositions is that the organic substances accumulated in the pores of the particulate material are released into the soil in a slow release manner. The following examples are provided merely to illustrate the invention and are not intended to limit the scope of the invention in any manner.

WO 01/42171 PCT/ILOO/00816 - 25 EXAMPLES Preparation of butylated silica nano-particles Silica nano-range particles (diameter of 2-50 nanometer) were modified by reacting the same with n-butanol to yield hydrophobic butylated silica particles silica-[Si-O-n-butyl]. (hereinafter referred to as butyl-silica). Excess of butanol was removed from the reaction system by evaporation. The particles were then heated at 200-260 0 C followed by their cooling at room temperature to yield a white powder-like particulate material. Urine treatment with butyl- silica nano-range particles Nano-range n-butyl silica particles (2-25nm) were introduced step-wise (eight portions of 2 gr. each) into a beaker containing a sample of swine urine (200 ml), until obtaining a snow-like interface layer at the top surface of the liquid. After each addition of the particles the system was mixed for 2-3 min. The initial pH of the system was 6.0, and the treatment was carried out at 180C, with air humidity of 65%. The malodors associated with the urine were substantially eliminated after 30 minutes. After 24 hours the liquid within the beaker obtained a pasty-like structure, substantially free of odors (pH of the liquid was 7.0). After an additional week, the pasty like substance lost 50% of its weight as a result of water evaporation and became an odorless lumpy powder. After WO 01/42171 PCT/ILOO/00816 - 26 additional two weeks, the material within the beaker became dry and had a powder-like structure (32 gr) comprised of the particles carrying organic substances, including about 16% (by weight) of ureic acid. These results indicate that the particles were able to withdraw from the urine the organic substances, prevent the formation and release of odors from the liquid and provide substantially clear water, which evaporated from the system. Preparation of methylated nano-range particles Silica particles (diameter of 2-250nm) were treated to carry methyl groups on the surface thereof by reacting the same with trimethylchlorosilane under gaseous conditions, for an 1 hr, at 250-300*C, during which hydrochloride was released from the system. The efficiency of the above described butylated or methylated silica particles, a combination of such particles, or a combination thereof with component B particles was determined. Results The efficiency of the following particles in preventing the formation and release of malodors was determined: silica- [Si-O-Si-(CH3)a]n (hereinafter referred to as CH3-silica); CHa-silica + n-butyl-silica (50%:50%); perlite WO 01/42171 PCT/ILOO/00816 - 27 (having a diameter of 2-3 mm and a porosivity of 95%) + CH3-Silica (98%:2%); claydite (having a diameter of 1.5-3 mm and porosivity of 50%) + CHa-Silica (98%:2%); and active coal particles (having diameters of 3-7mm) + CH3-Silica particles (98%:2%). The B particles were dried at temperature of 105 -120 C. The treated alkyl-silica particles were adsorbed onto the mineral derived or coal particles by electrostatic interactions. The tests were conducted as described above. Samples of pig urine and/or pig excrements were placed in a beaker, onto which the particulate material(s), was (were) introduced. The samples included urine alone or urine mixed with water (v/v 1:4); pig excrements alone or excrements mixed with urine (1:1). The time after which odors were no longer discernible above the interface layer was measured. Table I provided the results obtained for each type of particles and samples: Table I Particles CHa-Silica Butyl-silica CH3-Silica+ Perlite + Claydite + Carbon + Sample butyl-silica CHa-Silica CHs-Silica CHa-Silica Urea 40-60min. 30min. 30min. 30min. 30-60min. 30min. urea + water 60-90min. 30min. 30min. 30min. 30-60min 30min. Pigs excrements 30min. 30min. 30min. 30min. 30-60min 30min. Excrement + 40min. 30min. 30min. 30min. 30-60min 30min. urea WO 01/42171 PCT/ILOO/00816 - 28 In each sample, the interface layer was effective until total sample dried out. At the end of the process, the dry material in each case includes organic substances absorbed unto the interface layer creating a crust-like yellow-brownish solid layer. No malodor was detected, during the entire process. These results show that in the presence of the particulate material of present invention, the formation and release of malodors associated with the animal manure was eliminated after a short period of time. CH3-silica particles: a crust was formed at the top of the system with all samples. This crust layer becomes visible in 1-2 days and gets its final crumbly appearance when the sample is dried-out (within 10-20 days). C4H-silica particles: After about 24 hours a paste-like layer was formed at the top surface of the samples, after which a powder-like material containing ureic acid (16%) was obtained. The system containing urea and water became dry after about 12 days. Samples containing pig excrements became a lumpy material wherein the organic material is adsorbed onto the particulate material. When the sample contained a mixture of excrements and urea, the lumpy material was coated with a powder-like substance. CHa-silica + butyl-silica: The sample became dry after a week. A lumpy material containing the organic substances adsorbed onto the particulate WO 01/42171 PCT/ILOO/00816 - 29 material was obtained with the sample containing excrements, and covered with a powder like substance, when the sample contained also urine. Perlite + CH3-silica: A powder-like material was obtained when using urine or a mixture of urine and water It took 14 days until total dry-out at the room conditions. A lumpy material was obtained in the case of samples containing excrements which was coated with a powder like material when the sample contained also urine. All individual samples got dry within 2-3 weeks. Particulate material of the interface layer, dissolved copmounds, solids and organic substances created a solid crust. Clavdite + CH3-silica: A paste like (increased viscosity) layer was formed at the top surface of the samples after 3-4 days of incubation. During the treatment the viscosity has increased due to water evaporation while the remaining liquid form a kind of thick colloid thixotropic paste which became thicker and thicker until it was completely dried- out. Active carbon + -CHa-particles: a clear separation between the aqueous phase and organic phase was observed, especially in the case using samples containing urine and water. In this case, no increase in medium's viscosity was observed and active carbon which have adsorbed organic materials sunk to the bottom. As a result, the liquid has steadily became clearer and lost its black color.

Claims (55)

1. A process for treating liquid or semi-solid animal, including human, waste, and controlling malodor associated with same waste, comprising: (a) collecting said animal waste into a receptacle, to form a waste pool; (b) introducing onto said animal waste pool floatable, particulate material which forms an interface layer over a top surface of said waste pool; said interface layer has multiple functions, based on its chemical composition and physical structure, and provides changes in the properties and composition of the upper pool layers and/or its interaction with the overlaying atmosphere. The interface layer, in accordance with the desired function to be achieved, may contain at least one component, selected from the group comprising: (I) floatable, substantially hydrophobic nano-range particles having a diameter of less than 100nm, and preferably 2-40 nm (referred to as "component A"); (II) floatable, porous particles having both hydrophobic and hydrophilic groups (referred to as "component B"). Same particles, having a diameter of >lpm, may optionally be associated with (I) said substantially hydrophobic nano-range particles; with or without (2) WO 01/42171 PCT/ILOO/00816 - 31 substsntially hydrophilic nano-range particles (referred to as "component C") having a diameter of less than 100nm, and preferably, 2-40nm; and/or (3) photo-catalysts capable of decomposing organic substances and malodors; and/or (4) aerobic bacteria capable of degrading organic waste materials; (III) active carbon particles in association with component A and/or component B; (c) incubating said interface layer in said waste pool for a time sufficient to yield an effect of either of said functions, while periodically, if necessary, replacing or replenishing the interface layer with new such particles.

2. A process according to claim 1, wherein said component B is a high porous particle having 50-95% porosity.

3. A process according to claim, wherein said floatable component A particle is inherently hydrophobic or is an originally hydrophilic particle pre-treated to render it substantially hydrophobic. WO 01/42171 PCT/ILOO/00816 - 32

4. A process according to claim 3, wherein said particle is selected from the group of non-porous compounds named "oxide" and/or oxide-group(s) containing substances.

5. A process according to claim 3, wherein said particle is alkyl-silica.

6. A process according to claim 1, wherein said floatable component B particle containing both hydrophobic and hydrophilic groups, or inherently hydrophobic or hydrophilic particle pre-treated to render it partly hydrophilic or partly hydrophobic, respectively.

7. A process according to claim 6, wherein said particle is selected from the group of porous compounds named "oxide" and/or oxide-group(s) containing substances.

8. A process according to any of claims 1 to 7, wherein either component A and/or component B and/or component C particles are selected from the group comprising mineral-derived particles.

9. A process according to claim 8, wherein said mineral particle is selected from the group comprising silica minerals, alumina minerals and clay minerals. WO 01/42171 PCT/ILOO/00816 - 33

10. A process according to claim 9, wherein said silica mineral is pertile and said clay mineral is bentonite or claydite.

11. A process according to claim 10, wherein component B is selected from the group comprising perlite, bentonite and claydite.

12. A process according to claim 7, wherein component B is a plant material residue comprising amorphous oxide.

13. A process according to claim 12, wherein said plant residue is selected from the group comprising husk straw, peat, dry stems and sawdust.

14. A process according to claim 6, wherein said pre-treatment of component B particles included sintering of the porous particulate material to form air-filled pockets therein, which render the particles floatable.

15. A process according to claims 3 and 6, wherein said pre-treatment includes chemical binding of hydrophobic groups at least on the surface of said particle. WO 01/42171 PCT/ILOO/00816 - 34

16. A process according to Claim 15, wherein said pre-treatment is alkylation of functional groups present on the surface of said particles.

17. A process according to claim 1, wherein said interface layer comprises catalytic components, for catalytic decomposition of volatile substances released from said animal waste; said catalytic component is introduced onto the particulate material before or after introduction of said particulate material into said pool, or while being adsorbed onto said particulate material.

18. A process according to claim 17, wherein said catalytic component is a photo-catalytic component, being a complex or an oxide of a heavy metal.

19. A process according to claim 18, wherein said heavy metal complex comprises a non-posinous heavy metal selected from Fe, Cu, Co, or Ni.

20. A process according to claim 18, wherein said metal oxide is TiO 2 or A1 2 0 3 . WO 01/42171 PCT/ILOO/00816 - 35

21. A process according to claim 1, wherein said component C particles are SiO 2 , A1 2 0 3 or TiO 2 .

22. A process according to claim 1, wherein said interface layer conists of particles of component A and C adsorbed onto the surface of particle of component B.

23. A process according to claim 1, wherein said interface layer comprises active carbon particles or carbon-derived substances introduced into said waste pool before or after introduction of said particulate material or while being adsorbed onto said particulate material.

24. A process according to claim 1, wherein component A and C particles having the diameter of 2-50 nm.

25. A process according to claim 1, wherein component B particles having a diameter in the range of 1 pm to 5 cm.

26. A process according to claim 1, wherein said interface layer comprises a combination of component A and component B particles. WO 01/42171 PCT/ILOO/00816 - 36

27. A process according to claim 26, wherein said interface layer comprising 1-5% (by wt.) component A and 95-99% (by wt.) component B.

28. A process according to claim 1, wherein component B particles containing bacteria active in degradation of organic, and/or other biodegradable, substances in said animal waste.

29. A process according to any one of the preceding claims, being a batch-wise process.

30. A process according to any one of the preceding claims, comprising continuously or periodically addition of animal waste to said receptacle.

31. A floatable, particulate material containing at least one component, selected from the group comprising: (a) floatable, substantially hydrophobic nano-range particles having a diameter of less than 100 nm, and preferably, 2-40 nm (referred to as "component A"); (b) floatable, porous particles having both hydrophobic and hydrophilic groups (referred to as "component B"). Same particles, having a diameter of >1lm, may optionally be associated with (1) said substantially hydrophobic nano-range particles; with or WO 01/42171 PCT/ILOO/00816 - 37 without (2) substantially hydrophilic nano-range particles (referred to as "component C") having a diameter of less than 100nm, and preferably, 2-40nm; and/or (3) photo-catalysts capable of decomposing organic substances and malodors; and/or (4) aerobic bacteria capable of degrading organic waste materials; (c) active carbon particles in association with component A and/or component B; which after being introduced onto a pool containing liquid or semi-solid animal, including human, waste forms an interface layer over a top surface of said waste pool; said interface layer has multiple functions, based on its chemical composition and physical structure, and provides changes in the properties and composition of the upper pool layers and/or its interaction with the overlaying atmosphere.

32. A floatable particulate material, according to claim 31, having 50-95% porosity.

33. A floatable particulate material, according to claim 31, being inherently hydrophobic or being treated to render at least part thereof hydrophobic. WO 01/42171 PCT/ILOO/00816 - 38

34. A floatable particulate material, according to claim 31, wherein said particle is selected from the group of compounds named "oxide" and/or oxide-group(s) - containing substances.

35. A floatable particulate material, according to claim 31, comprising silica-derived particles.

36. A floatable particulate material, according to claim 31, comprising mineral-derived particles.

37. A floatable particulate material, according to claim 36, wherein said mineral is selected from the group comprising silica minerals, alumina minerals or clay minerals.

38. A floatable particulate material, according to claim 37, wherein said silica mineral is perlite and said clay mineral is bentonite or claydite.

39. A floatable particulate material, according to claim 31, comprising plant material residues. WO 01/42171 PCT/ILOO/00816 - 39

40. A floatable particulate material, according to claim 39, wherein said plant material residues are selected from husk straw, peat, dry stems and sawdust.

41. A floatable particulate material, according to claim 31, wherein said particles are subjected to a pre-treatment.

42. A floatable particulate material, according to claim 41, wherein component B porous particles are subjected to a pre-treatment including sintering of at least part of said pores to form air-filled pockets therein which renders said material floatable.

43. A floatable particulate material, according to claim 41, wherein said treatment includes chemical binding of hydrophobic groups at least to the surface of said particulate material.

44. A floatable particulate material, according to claim 31, comprising nano range-particles having a diameter of 2-50 nm.

45. A floatable particulate material, according to claim 31, comprising particles having a diameter in the range of 1 pLm - 5 cm. WO 01/42171 PCT/ILOO/00816 - 40

46. A floatable particulate material, according to claim 31, 44 and 45, wherein said nano range-particles are adsorbed onto particles having a diameter in the range of 1 jtm - 5 cm, prior to introduction thereof onto said animal waste pool.

47. A floatable particulate material, according to claim 31, wherein component C is SiO 2 , A1 2 0 3 or TiO 2 .

48. A floatable particulate material, according to claim 31, wherein said nano-range particles of component A and component C are adsorbed onto surface of particles of component B

49. A floatable particulate material, according to claim 31, wherein said nano-range particles of component A and component C are adsorbed onto surface of active carbon or carbon-derived particles.

50. A floatable particulate material, according to claim 31, carrying adsorbed onto particle surface catalytic components, for catalytic decomposition of volatile substances, including malodors. WO 01/42171 PCT/ILOO/00816 - 41

51. A floatable particulate material, according to claim 50, wherein said catalytic components are a heavy metal complex or oxide thereof.

52. A floatable particulate material, according to claim 51, wherein said heavy metal complex comprises a non-posinous heavy metal selected from Fe, Cu, Co or Ni.

53. A floatable particulate material, according to claim 51, wherein said metal oxide is TiO 2 or A1 2 0 3 .

54. A floatable particulate material, according to claim 31, wherein component B particles containing bacteria active in degradation of organic, and/or other biodegradable, substances.

55. A fertilizer composition obtained during, and/or following, and/or as a result of a process for treating liquid or semi-solid animal, including human, waste, and controlling malodor associated with same waste, according to any of the preceding claims.