EP2793608A1

EP2793608A1 - Biopolymers isolated from residual biomass and fossil source; production processes and product use

Info

Publication number: EP2793608A1
Application number: EP12824749.1A
Authority: EP
Inventors: Enzo Montoneri; COrrado MONTONERI
Original assignee: Universita degli Studi di Torino
Current assignee: Universita degli Studi di Torino
Priority date: 2011-12-22
Filing date: 2012-12-21
Publication date: 2014-10-29
Also published as: ITTO20111192A1; WO2013093951A1

Abstract

Composition, and processes for the production and use of mixture of water soluble biopolymers, said mixture comprising an organic fraction and a mineral fraction, the organic fraction comprising polymer molecules having a molecular weight included between 5 and 500 kDalton and a polydispersion index included between 6 and 53, wherein the organic fraction contains, in % weight of dry substance, 37 ≤ C ≤ 65; 3 < N ≤ 7, and N and C mean nitrogen and organic carbon being distributed among the following types of carbon atoms and functional groups with the following composition expressed as molar fraction of the total organic carbon: 0.3 < C_al ≤ 0.6; CN ≤ 0.1; OMe ≤ 0.1; 0.3 ≤ OR ≤ 0.6; 0.02 ≤ OCO ≤ 0.08; 0.07 ≤ Ph ≤0.30; 0.02 ≤ PhOH ≤ 0.06; PhOR/Ar ≤ 0.09; 0.04 ≤ COOH ≤ 0.12; CON ≤ 0.12; C=0 ≤ 0.05; and the mineral fraction contains, in % weight of dry substance, ashes ≤ 30; Si ≤ 3.0; Fe ≤ 0.9; Al ≤ 0.8;' Mg ≤ 1.2; Ca ≤ 6.5;. K ≤ 10; Na ≤ 10; Cu ≤ 0.03; Ni ≤ 0.01; Zn ≤ 0.05; Cr ≤ 0.003; Pb ≤ 0.01.

Description

BIOPOLYMERS ISOLATED FROM RESIDUAL BIOMASS AND FOSSIL

SOURCE; PRODUCTION PROCESSES AND PRODUCT USES

The invention concerns the. chemical composition, the production and the uses of water soluble biopolymers isolated form residual biomass and from fossil source.

The interest in biomass as renewable energy source for sustainable development stems from the concern of fossil sources depletion and from the need to manage higher and higher amounts of wastes, due to increasing human consumption habits. Since most fossil sources are used as fuel, the exploitation of biomass has been so far conceived solely to produce fuel. Thus, current^' biomass treatment technology has been developed mainly to perform combustion for the production of thermal and electrical power, chemical reactions to obtain biodiesel, and fermentation to yield biogas and bioethanol. Such technologies are however expensive. They, cost more than the market value of the obtained energy or fuel. The reason for this is due to a number of unfavorable features which are typical of biomass: i.e. high water content,, distribution over wide surface areas, low conversion of organic carbon to the desired product and/or no exploitation of the residual unconverted organic fraction. It is commonly, agreed that this situation could be improved by developing biorefineries which were run with the same strategy as oil and carbon refineries: i.e. to valorize all products either in the fuel as well as in the chemicals' market. Supporting this approach, several studies estimate that the sole residual biomass, annually produced worldwide, has a potential energy content which could virtually be used to replace the current oil consumption. To this scope, one could in principle exploit the potential bioenergy contained in residual biomass from agriculture and forest source, from wood processing, from animal dejections, from wastes of the paper and pulp industry, and of the food industry, from slaughter houses, from the meat production industry, from sewage sludge, and from urban biowastes.

The sustainable use of such residual biomass depends however either on the biomass nature and on the technology needed for its. transformation. Urban biowastes, for instance, are in. principle mostly favored as cost effective source. As result of population urbanization and increasing human consumption habits, they are concentrated in confined spaces and have relative high organic carbon content. Agricultural residues, vice versa, are spread over wide surface areas; their viability as energy source varies greatly depending on the geographical location and on the intensity of local agriculture practices. As to technology, the current waste treatment plants comprise facilities for biomass combustion for power houses, anaerobic digestors for biogas production, and aerobic digestors for compost production. Incinerators rise public concern for fear of fine dust emission in air, whereas fermentation facilities are more accepted by population. Composting plants however do not allow to obtain a significant revenue, since the product is scarcely marketable. Biogas plant on the contrary produce an easily marketable product. However, the- cost of biogas production is higher than its sale value. This situation stems from a number^" of critical points connected to the efficiency of the fermentation process, leading to no more than 50 % conversion of the potential chemical energy contained in the process biomass feed. Consequently, biogas plants must bear the cost of disposing the unconverted organic residue, conventionally known as the process . digestate . Attempts to overcome these critical points are the codigestion of biowastes of different nature and the development of plants performing anaerobic digestion of the biomass input, followed by composting of the digestate. Relatively to sole composting plants, the combined anaerobic/aerobic process produces less biomass volume to dispose. This however keeps the plant cost/revenue ratio still quite high.

The above state of art has offered worthwhile scope for developing cost effective processes to obtain high added value products from residual biomass and fossils, •specifically soluble biopolymers to use in place of current chemicals obtained from oil and coal. According to the present invention this scope is achieved by the procedure and claims reported hereinafter, all of which are comprised in the present invention.

Generally, the invention comprises a mix of water soluble biopolymers (SBP) constituted by two basic parts, one organic and the other mineral. These two parts aire intimately bonded to each other. The organic fraction is composed by molecules with molecular weight comprised between 5 and 500 kDalton ^' and polydispersivity index between 6 and 53. The mineral fraction contains silicon, iron, aluminum, magnesium, calcium, potassium, sodium, copper, nickel, -zinc, chromium, cadmium and lead.

This water soluble biopolymers' mix is obtained according to a procedure comprising the following steps: a. to provide biomass or fossil material containing organic matter;

b. to hydrolyze at basic pH the biomass or the fossil material in order to obtain a liquid hydrolysate and a residual solid phase; and

c. to treat the liquid phase by one or both the following procedures:

i. precipitation at acid pH to yield a liquid phase and a precipitate containing the biopolymers, these latter in solid form separated from the liquid phase by conventional means such as filtration and/or centrifugation;

ii. membrane filtration to yield a permeate and a retentate, this latter containing the biopolymers mix in solution or gel form.

The water soluble biopolymers mix, constituting the matter of the present invention, may be used as follows:

(i) as chemical auxiliary for remediation of and/or for COD abatement in soil and water contaminated by toxic or undesired organics and/or metals, particularly heavy metals;

(ii) as chemical additive for the inhibition of organic nitrogen mineralization, and/or for the reduction of ammonia, in fermentation processes; (iii) as chemical promoter of photosyntesis in plants, preferably cultivated for human and animal food production and consequently as additive to enhance plant chlorophyll production and growth, and agriculture productivity;

(iv) as binder for the fabrication of materials and objects where particles' binding is required.

The following Figures are attached as examples of biopolymers (SBP) effects in agriculture applications.. The Figures are meant to help the description of some, but not all_/ features of the present invention:,

- Figure 1. Dependence of the chlorophyll content (Spad units) in red pepper leaves upon SBP dose applied to soil .

- Figure 2. Dependence of red pepper plant growth indexes and productivity upon chlorophyll content

Hereinafter, several examples are reported to provide details of the present invention and help a full comprehension of the different aspects of_. the present invention. These specific examples however are not meant to be limitative of the invention as the invention, according to its principles and guidelines, may be put into practice by a combination of procedures, components, materials, and other experimental details which will allow the expert chemist and/or potential user to optimize processes' and products' performance. In the following description, reference to a specific form of use or application of the invention means that the reported details are only one of the many ways to apply the present invention. Thus, different ways to apply the present invention are reported hereinafter. Furthermore, the experimental features of single application forms may be combined in several ways with specific details reported for other applications to optimize the realization of the present invention for the intended application.

Examples are hereinafter entitled in different ways. Titles must not be taken as limitative of the invention. They are used only for the purpose of summarizing the specific content of the described example.

The following description demonstrates that from the organic humid fraction of solid urban refuse one can obtain water soluble biopolymers (SBP) which are high added value for use in several applications to substitute partly or entirely current commercial chemical products obtained from oil or other fossils. Due to their origin, the above SBP, compared to fossil derived commercial . products, have the advantage to be obtained from virtually no cost source, to have friendly environmental impact, to offer a wide choice of different ready for use substances, depending on the type of sourcing biowaste, without need of added costs for chemical manipulations, except for chemical hydrolysis and product separation, as reported in the examples hereinafter described.

Based on the market prices for current commercial products, the SBP potential monetary value in the chemicals' market may be estimated from 1 to several tens € kg^-1. This potential revenue is from 5 to hundred times higher than that obtainable from the same sourcing biowaste upon using it for the production of thermal power by combustion (about 0,20 € kg^"1 of organic matter) or as fertilizer by composting (about 0,024 € kg^-1 of organic matter) . On this basis, the product and processes of the present invention, if adequately integrated within the current waste treatment plants processing urban biowastes o residual biomass from other source, may contribute to turn such waste treatment plants into biorefinery, where the waste treatment cost is compensated form the revenue obtained by the SBP sale. In this perspective, biowastes would not be solely an economic burden for society, but become source of revenue and new jobs.

The present invention comprises the following items: (i) water soluble biopolymers (SBP), isolated from residual biomass or fossil material containing organic carbon and mineral elements, identified as follows; the organic carbon fraction has molecular weight comprised between 5 e 500 kDalton, polydispersivity between 6 and 53, presence of aliphatic carbon chain substituted by aromatic rings and several different functional groups such as COOH, CON, C=0, PhOH, O-R, OAr, OCO, OMe, and NRR' , where R and R' is alkyl or H; the mineral fraction contains compounds of silicon, sodium, potassium, calcium, magnesium, aluminum, iron, copper, zinc, chromium, cadmium and lead;

(ii) the processes to obtain the above SBP;

(iii) using the above SBP as chemical auxiliary for remediation of and/or for COD abatement in soil and water contaminated by toxic or undesired organics and/or metals, particularly heavy metals;

(iv) using the above SBP as chemical additive for the inhibition of organic nitrogen mineralization, or reduction of ammonia content, in fermentation processes;

(v) using the above SBP as chemical promoter of photosyntesis in plants, preferably cultivated for human and animal food production and consequently as additive to enhance plant ^■ chlorophyll production, and growth and agriculture productivity;

(vi) using the above SBP as binder for the fabrication of materials and objects where particles' binding is required.

The invention is applied also to any potential fossil source of SBP. It is primarily meant for the valorization of residual biomass produced by human activities in order to be exploited as source of products to use in chemical and environmental technology, in agriculture and animal husbandry, and thus to replace partly or entirely current commercial products used for the same above applications.

In the perspective of technological application and scale up of the present invention to commercial production, it will be possible to turn current waste treatment plants to biorefinery for the production of fuel and added value chemicals for the above (iii-vi) uses, with consequent economic, environmental and social benefits.

The first form of application of the present invention is the chemical composition of new products of natural biological source, named water soluble biopolymers (SBP) . These products are entirely new, since the below reported composition has never before described and/or reported by anyone. The peculiarity of the chemical composition of SBP lies in the presence of both the organic and mineral components, where the organic fraction is bonded to the mineral fraction, both having a sinergic role. In essence, the organic component keeps in solution the mineral component, and the latter in turn . modulates the properties and behavior of the organic component.

The SBP organic fraction is described in more details as a mixture of molecules with 5-500 kDalton molecular weight and 6-53 polydispersivity index. Such polymeric molecules are characterized by the presence of aliphatic carbon chains, aromatic carbon, and polar functional groups, free and/or bonded to the above reported mineral elements, to yield the following % weight relative chemical composition: 37 < C < 65; 3 < N < 7; ceneri < 30; Si < 3,0; Fe < 0,9; Al < 0,8; Mg < 1,2; Ca < 6,5; K < 10; Na < 10; Cu

< 0,03; Ni < 0,01; Zn < 0,05; Cr < 0,003; Pb < 0,01.

In the above composition, N e C mean organic nitrogen and carbon distributed over the above described carbon types and functional groups with the following composition expressed as mole fraction of the specific carbon type over the product total organic C:.-0,3 ≤ C_al < 0,6; CN < 0,1; OMe

< 0,1; 0,3 < OR ≤ 0,6; 0,02 < OCO < 0,08; 0,07 < Ph <0,30; 0,02 < PhOH < 0,06; PhOR/Ar < 0,09; 0,04 < COOH < 0,12; CON < 0,12; C=0 < 0,05, where C_al = aliphatic C bonded to H and/or to other- aliphatic C and/or to aromatic C, CN = C bonded to amino functional groups, OMe = metoxy C; OR = alcoxy C, OCO = anomeric C, Ph = aromatic C bonded to H and/or to other aromatic C and/or to other aliphatic C, PhOH = penol C, PhOR/Ar = phenoxy C, COOH = carboxylic C, CON = amide C, C=0 = keto C.

The analytical protocol to identify and characterize the SBP comprises the determination of i) mineral elements by atomic absorption e ii) of C and N by microanalysis, potentiometric titration of COOH e PhOH groups, solid state ¹³C nuclear magnetic resonance, and elaboration of experimental data described in the examples' section.

The second form of application of the present invention lies in the SBP source. The SBP are isolated from residual biomass of urban, agriculture, forest, agroindustrial, animal (as for instance manure) and industrial source, such as for example, lignin and polysaccharide material contained in the liquor of the cellulose pulp process, in the wastes of the wood processing industry, of the food industry, of slaughter houses, in sewage sludge. The SBP can also be obtained from fossils such as peat, lignite, leonardite.

The third form of application of the present invention lies in the process to obtain the SBP. From all above sources, the SBP can be obtained using two process, separately or combined, hereinafter named hydrolysis/precipitation separation process (SP) and hydrolysis/membrane separation process (MS) . Each process comprises two phases, hereinafter named hydrolysis and product separation; the two processes differ one from the other in the separation phase.

In the hydrolysis phase, the above specified residual biomass (RBM) or fossil material is treated with water at 8-13 pH for 2-4 hours with a liquid/solid ratio comprised between 8 and 4 and at temperature comprised between 60 e 200 °C. At the end, the settled solid phase containing the insoluble organic residue (IOR) is separated from the surnatant liquid phase containing the soluble organic substances (SOS) produced by the RBM hydrolysis.

The SOS separation is performed by one or both the SP o MS processes.

In the SP process, the SOS phase is acidified to pH < 4 in order to precipitate the SBP products. These are recovered in solid form by centrifugation and/or filtration, followed by washing and drying.

In the MS process, the SOS phase is pumped through a microfiltration (MF) , ultrafiltration (UF) , nanofiltration (NF) or dialysis membrane unit to yield a retentate (RF) and a permeate (-PF) phase.

The RF phase contains the SBP in solution or gel form up to 17 % concentration and the desired pH, without need of adding other reagents to correct pH to the desired value. The RF may be used as such or after drying to produce solid SBP.

The PF phase, eventually added with alkali to the desired pH, is recycled to the hydrolysis reactor to perform the reaction for the next RBM lot. In this fashion, upon increasing the number of reaction/separation/re cycling operations, the PF is enriched until saturation with organics having molecular weight below 5000 D. When the organics concentration is near the solubility value, the PF phase is dialyzed to yield water to recycle to the hydrolysis reactor and a concentrated solution of organics. This latter, after water evaporation, yields a residue containing organics with molecular weight below 5000 D.

When analyzed, the SBP products obtained as above have 25 % ash content, due to the presence of the mineral elements. The following procedure yields SBP with reduced mineral content. Acidifying the above RF to pH 1,5-3 yields a precipitate. This is separated from the acid mother solution by centrifugation and/or filtration, washed repeatedly with HC1 or HF solution and dried. As shown below, the reduced mineral content changes the properties and performances of the product. The reduced mineral content occurs due to the following reactions:

RCOOM + HX = RCOOH + MX ( 1 ) PhOM + HX = PhOH + MX ( 2 )

CNDDDM + HX = CN + MX + H⁺ ( 3 ) ,.

where M is the mineral element, HX is the mineral acid, RCOOM, PhOM e CNDDDM are the carboxylic, phenol and amino groups holding M with ionic and donor-acceptor bonds, RCOOH, PhOH e CNDDDM are the corresponding metal free organic functional groups. The products containing the metal free functional groups are insoluble in water. This property allows to separate easily the mineral elements (M) in water soluble form as chlorides (X = CI) or fluorides (X = F) .

A fourth form of putting into practice the present invention is the use of SBP, and the related process, as auxiliaries for remediation of soil and waters contaminated by undesired organics and metals.

Te process is based on the interaction between SBP in solution and one or more contaminants (C) , either organic and mineral, which are present in the soil or water to be remediated. This interaction yields the SBP-C adduct in solution. The adduct can then be easily separated by precipitation at acid pH o ultrafiltration. For the above chimical features and properties, the SBP are sequestering agents for the C contaminants. In this fashion, the biopolymers donate to the contaminant their same solubility properties. By bonding_. the contaminant to their macromolecular structure, the SBP increase the contaminant water solubility at pH > , do not allow the contaminant to permeate through ultrafiltration membranes with molecular cut off above 5000 kDalton, and precipitate together with the contaminant at acid pH.

Typical examples to use the SBP according to this mechanism are described in the examples reported below. These examples show how, by use of SBP, either the SBP and the contaminant may be recovered in SBP-C adduct form, at 98-99 % level. It is possible in this fashion to perform efficient remediation of the soil or water to be treated, producing solid and liquid effluents meeting the legislation requirements for their use, except for the SBP- C adduct. The adduct, separated by precipitation or membrane ultrafiltration, can be disposed by incineration to yield a mineral residue to recycle to the chemical industry for further uses.

The above process may also be used for the selective recovery of specific heavy metals, for example V, Cu, . n, Cd, Hg, Pb, Ni_/ Cr, Ag and others, from waste materials such as obtained by treating any refuse by incineration of the organic fraction. The same process may be used for the. abatement of COD industrial organic waste effluents, for example exhausted dyeing baths of the textile industry and others .

A fifth form of putting into practice the present invention is using SBP to inhibit the mineralization of organic N, or to decrease the ammonia content, in anaerobic fermentation processes of any nature, such as those for production of biogas, or of any biofuel, starting from dedicated crop or from residual biomass of urban, agriculture, and agro-industrial source, and the fermentation processes occurring in the animal digestive tract.

In bioreactors treating biowastes for biogas production, for example, the mineralization of organic N by natural micro-organisms leads to the production of ammonia as byproduct. This will inhibit biogas formation, reduce the conversion of organic matter to biogas, and yield a digestate residue. The digestate cannot be used in agriculture or dumped into soil due to the presence of excess ammonia and/or inorganic N compounds above legislation requirement, and therefore needs further remediation treatment.

By the present invention, the addition of SBP in adequate amounts to the fermentation liquor allows to optimize the biogas production process, by enhancing the product yield, and to obtain a digestate with reduced ammonia content by 30 %. or more.

In the animal digestive tract, the mineralization of the organic N, fed to the animal with the protein containing feed, results in lower feed utilization for the animal growth, and thus in reduced animal growth rate. The N mineralization also increases ammonia and/or nitrogen •oxides emission in the animal dejections, which therefore impact negatively on soil, and on surface and ground waters quality.

By the present invention, the addition of SBP in adequate amounts to the animal diet allows to decrease the mineralization of organic N, to enhance the animal growth rate and to reduce the environmental impact of animal dej ections .

In conclusion, in addition to enhancing the efficiency of anaerobic fermentation, the SBP allow to obtain a process effluent, either gaseous, and liquid or solid (the bioreactor digestate or the animal dejections) , with reduced environmental impact, with significant - economic benefits for waste treatment facilities and for the animal production industry.

A sixth form of putting into practice the present invention is the use of SBO as binding agents. The SBP may be used as binder for the fabrication of objects in the desired form, said objects comprising organic or inorganic oxides components. The example section describe for instance the fabrication of animal feed in pellet form. However, the binding properties of SBP may be exploited for the manufacture of materials and objects for house building and road construction, such as cement, ceramic tiles, road pavement, or used in any other industrial sector where binders are required.

A seventh form of putting into practice the present invention is using SBP at proper dose in order to enhance photosynthesis, with consequent increase of plant leaf chlorophyll content, and of plant growth and agriculture productivity. One example described hereinafter shows that the addition of SBP at proper dose to soil used for cultivation of horticultural species enhances leaves chlorophyll content, plant growth rate, and early and total fruit production at the end of the cultivation/growth cycle.

Examples

Process to- obtain SBP by alkaline hydrolysis and membrane separation.

In a reactor equipped with mechanical stirrer and facilities for heating by diathermic fluid circulation or electrical coil, one part in weight of residual biomass (RBM), of urban, agriculture, agroindustrial source, or from effluents of wood processing, and of the above listed fossil materials, such as for instance compost obtained from the organic humid fraction of urban refuse, is treated with 4 parts in weight of pH 13 water containing NaOH or KOH, at 65 °C for 4 hours under stirring. At the end, stirring is stopped, and the solid/liquid suspension is allowed to settle until the surnatant liquid phase flows easily through a 0.125 mm sieve. This allows to separate and collect about 70 % of the starting liquid volume. The collected liquid phase contains the water soluble organic substances (SOS) , produced by hydrolyzing the starting RBM.

The residual liquid phase, about 30 % of the starting alkaline water, is retained by the solid phase settled in sludge consistency. This material contains the insoluble organic residue (IOR) , and part of SOS contained in the water phase retained by the settled IOR.

The sludge is washed with a volume of fresh water equal to 30 % of the starting volume of alkaline water before the hydrolysis, in order to displace the SOS phase retained by the IOR solid phase. During this operation, the resulting solid/liquid suspension is kept under stirring at room temperature for 1 hour, and afterwards it is allowed to settle for 1 hour. The surnatant liquid phase is withdrawn from the reactor and added to the hydrolyzate first removed from the reactor. The total collected liquid contains SOS at 3 % concentration and pH 10. This liquid is conveyed to the ultrafiltration membrane having 5 kD cut off. The membrane inlet and outlet pressure values are 4 and 2 bar respectively. This allows to obtain a retentate (SOSRUF) volume equal to 25 % of the inlet volume. By repeating this operation, eventually adding water to the retentate withdrawn from the membrane unit, and/or increasing the pressure gradient through the membrane, the SOS pH may be lowered and the SOS concentration in the retentate enhanced up to 17 % by weight.

The permeate (SOSPUF) , having 11 pH, contains 0,5 %, or less, of water soluble organics with molecular weight below 5 kDalton.

On the contrary, SOSRUF contains the SBP with molecular weight above 5 kDalton. These products have relative chemical composition within the ranges above specified (see first form of application) .

The SOSRUF -may be dried to yield SBP in solid form or used as such depending on the product intended successive use. The SOSPUF is recycled to the hydrolysis reactor to wash IOR, or to repeat the hydrolytic treatment on the same IOR, or to perform the hydrolysis of a new RBM lot.

The hydrolysis may be carried out at various pH values comprised between 9 and 13. However, SBP yields will decrease at lower pH. Furthermore, depending on the RBM nature, in order to increase the product yield, it may be necessary to increase the reaction temperature up to 200 °C, working under autogenous pressure as required by the reaction temperature.

Process to obtain SBP by alkaline hydrolysis and precipitation .

Hydrolysis of RBM and the washing of IOR are performed as above. However, the resulting SOS solution is acidified with a mineral acid to pH < 4 to yield a precipitate. This is separated from the acid liquid phase by centrifugation, washed with an equal volume of water, and dried to yieldSBP. The product has chemical composition within the ranges above specified.

Process to obtain SBP with reduced mineral content. The SBP obtained by the hydrolysis/membrane separation process are precipitated from the SOS solution at pH < 4 or, if obtained in solid form, they are washed with HC1 at 1/2-1/4 solid/liquid weight/volume ratio, depending upon the used HC1 concentration. The solid phase is washed with water until the collected washings have pH above 3. The solid phase is afterwards washed with concentrated HF at 1/4 solid/liquid weight/volume ratio, then washed with water to pH 3 and finally dried. The SBP obtained by the hydrolysis/precipitation process are washed by the same procedure reported above for the solid products sourced from the membrane separation/precipitation process.

Characterization of SBP.

The mineral elements concentration of SBP are obtained after mineralization of the sample with HNO₃-HF at 1:3 in v/v ratio and analyzed by atomic absorption spectroscopy. The C and N concentration are obtained with C. Erba NA-2100 type microanalyzer .

The content of carboxylic and phenol groups is determined by potentiometric titration as follows. Deionized water is boiled under nitrogen flux to remove dissolved carbon dioxide. This water is used for sample preparation. The SBP sample is dissolved at 0,6 g L^"1 concentration in 1 N KOH. The pH D.13 resulting solution is titrated with IN HC1. A similar titration is performed on a blank sample which does contain any SBP, but contains the same alkali amount as the SBP sample. The titration is performed with an automatic instrument such as the Cryson Compact having a resolution of 1 μΐ titrant. In this condition, one obtains pH vs. titrant volume curves showing two inflection points. The COOH e PhOH concentration is calculated from these curves according to Graam method (Brunelot e coll., Chemosphere 1989, 19, 1413-1419).

The determination of the concentration of C types and functional groups is performed as follows. Solid-state 13C- NMR spectra are acquired at 67.9 MHz on a JEOL GSE 270 spectrometer equipped with a Doty probe. The cross- polarization magic angle spinning (CPMAS) technique is employed and for each spectrum about 10⁴ free induction decays is accumulated. The pulse repetition rate is set at 0.5 s, the contact time at 1 ms, the sweep width is 35 KHz and MAS is performed at 5 kHz. Under these conditions, the NMR technique provides quantitative integration values in the different spectral regions. Signals in the 13C NMR spectra are identified based on chemical shift referred to tetramethylsilane . Signals' assignment as a function of the resonance range are: 0-53 ppm aliphatic C, 53-63 ppm O-Me or N-alkyl C, 63-95 ppm O-alkyl C, 95-110 ppm di-O-alkyl C, 110-140 aromatic C, 140-160 ppm phenol or phenyl ether C, 160-185 carboxyl C, 185-215 keto C. Signals' band areas are measured and -assumed to correspond to the relative mole/mole concentration of the above identified functional groups. Further breakdown of concentration of C types and functional groups is obtained according to the assumption underlying the following equations: PhOR = PhO - PhOH (1), ■CON = COX - COOH (2), N-alkyl = N - CON (3), where PhOR and COX are determined from 13C NMR spectra, PhOH and COOH by potentiometric titration and N is the total nitrogen content by microanalysis.

Molecular weight measurements are, performed on SBP solutions by "size exclusion chromatography (SEC)" coupled to on line "multi-angle light scattering (MALS) " .

Use of SBP and, e related process, for remediation of soil contaminated by undesired organics and metals.

Soil, contaminated by undesired organics and metals, is treated with SBP water solution at 0,01-1 SBP dry matter/soil ratio and 5-10 water/soil ratio.

The solution and soil are held in contact until the partition equilibrium is reached; i.e. until the contaminant concentration in the water phase does not change anymore with time. The solution is the separated from^" the soil phase by centrifugation and/or filtration.

Depending on the type of soil and contaminant, the soil sample may need to be washed repeatedly with fresh solution aliquots until the contaminant concentration in the soil is below the desired concentration.

The recovered washing aliquots are collected together and processed by precipitation or membrane filtration. In the first case, the SBP solution is acidified with a mineral acid to pH < 4 to yield a precipitate containing the contaminant (C) bonded to SBP (SBPC-PR) , which is centrifuged and separated from the liquid phase. The

SBPC-PR may be incinerated to remove all organics, and the residual mineral product may be recycled to further specific uses. The acid liquid phase is used again to precipitate other BPSC-PR obtained from the washings of other soil aliquots.

In the second case, the recovered SBP solution containing the contaminant washed out from the soil is conveyed to an ultrafiltration membrane with 5 kDalton cut off, applying 4 and 2 bar inlet and outlet membrane pressure respectively, until the retentate (SBPC-RUF) volume is reduced to 25 % or less relatively to the starting membrane feed volume. The SBPC-RUF may then be dried and burned as the above SBPC-PR. The permeate (PUF) is used to make up fresh SBP washing solution to use for treating other contaminated soil aliquots.

This soil washing process may be carried out in continuous mode, by adequately setting the soil/solution contact time depending on the type of soil and contaminant to treat.

With the above processes, it is possible to optimize the process parameters, such as the liquid/soil ratio, the SBP/soil ratio, the liquid/soil contact time, in order to achieve satisfactory removal of the contaminant from the soil, and over 99 % abatement of contaminant and COD from the recovered washing solution, either by precipitation and/or membrane filtration.

In these remediation processes, the use of SBP with reduced mineral content allows to increase the removal efficiency referred to the used SPB weight. This benefit however may be accompanied by greater absorption of SBP by the soil. This phenomenon is likely due to the soil-SBP cation exchange. Thus, the type of SBP to use must be chosen depending on the nature of the soil to treat.

As can be realized from the above described SBP composition range, the present invention covers a wide variety of SBP products, which are available thanks to the variety of available biowastes. The expert/potential user in the field has therefore a wide range of available products to tailor its product choice and to optimize the washing process according to the type of soil to be treated.

Use of SBP and, e related process, for remediation of ground waters or industrial effluents contaminated by undesired organics and metals. Ground waters or industrial effluents contaminated by undesired organics and metals are added with SBP in solid or water solution form to yield a final 0,1-10 % SBP solution. This solution is treated by precipitation or membrane filtration as describe above. Optimizing the process parameters, such as SBP concentration and contaminant-SBP contact time it is possible to achieve 99 % abatement of contaminant, either by precipitation and/or ultrafiltration.

Use of SBP to inhibit organic nitrogen mineralization in anaerobic fermentation processes of organics in biogas production reactors fed with dedicate crops o residual biomass of urban, agriculture, agro-industrial and animal origin .

A 3-40 % biomass suspension in water, containing organic, nitrogen deriving from dedicate crops o residual biomass of urban, agriculture, agro-industrial and animal origin, is added with 0,1-1 % SBP and allowed to undergo anaerobic fermentation. The final ammonia concentration . in the fermentation liquor and/or in the gas phase will result more than 20-30 % lower relative to the same process carried out in the absence of SBP.

For example, a suspension containing 3 % of organic humid fraction of urban refuse from separate source collection undergoing anaerobic fermentation in a continuous reactor kept at 55 °C, run in the stationary state, yields biogas with less than 0.5 ppm ammonia, 35 % methane e 15 % carbon dioxide, and the digestate liquor containing 1350 mg IT¹ ammonia and 1520 mg L^"1 total Kjeldhal nitrogen in solution.

The same fermentation carried out in the presence of 0,2 % SBP concentration in the fermentation liquor yields biogas with less than 0.5 ppm ammonia in the gas phase, 65 % methane, and 35 % carbon dioxide, and the digestate liquor containing less than 25 ppm ammonia and 1400 ^' mg L^"1 total Kjeldhal nitrogen in solution.

The comparison of material balance data in the two cases yields the following results: for the fermentation carried out in the absence of SBP, 78 % organics conversion, 4.7 yield of methane moles per kg of converted organics; for the fermentation in the presence of SBP, 86 % organics conversion, 8.8 yield of methane moles per kg of converted organics.

The data clearly demonstrate that SBP lowers greatly

^■ ammonia production and enhances methane yield.

Use of SBP to inhibit organic nitrogen mineralization during animal digestion of protein feed. Example a. In vitro fermentation of animal feed containing protein in the presence of cecal content from slaughtered pigs.

The following materials are used. 1) 11 % SPB water solution. 2) Standard feed for. pigs. This material is pre- digested to simulate ileal digestion by incubation in acid pepsin solution at 37 °C for 4 h, followed by incubation in pancreatin solution at pH 7.5 and 37 °C for 4 h. After enzymatic digestion, the preparation is centrifuged, washed twice with distilled water, centrifuged, and dried at 60°C overnight. The pre-digested fermentation feed substrate is characterized by the following analytical data as % w/w referred to dry matter: crude protein 4.44, crude fiber 8.68, crude fats 4.96, and starch 45.72. 3) Cecal content collected from pigs immediately after slaughtering and filtered before use. This material is used as incubation liquor.

Procedure: The SBP solutions, the feed substrate and the cecal content are used to prepare the fermentation liquors diluted with McDougall buffer. These contain 0.40 % feed substrate, · 31 % cecal content, 60 % buffer, 0-1-0.2 % SBP. The final pH of the freshly prepared fermentation liquor is 6.5.

The results show the following changes for the fermentation in the presence of SBP as compared to the same fermentation in its absence:

(1) total gas production decreases by 6 to 40 % ;

(2) volatile acid production increases;

(3) ammonia production decreases by 8 to 20 %;

(4) the highest effects are observed in the presence of SBP isolated from composted vegetable residues.

The data prove that SBP is effective in decreasing organic N mineralization occurring in the presence of pigs cecal content.

Example b. In vivo animal growth test with diet containing protein feed added with SBP.

Rabbits, 35 days old, having about 1 kg weight, are fed for 63 days with control diet (Table 1) and with the same diet containing 0,05 % e 0,25 % SBP until they reach 2,8-3,0 kg weight.

Under these experimental conditions, one can observe the following results. Daily feed intake by the animals is 100-140 g. Gas emission of animals treated with' SBP, compared to those treated with the control diet in the absence of SBP,. occurs with 5 % lower ammonia and methane content in the case of 0,05 % SBP treatment and with 27 % lower ammonia and 19 % lower methane content in the case of 0,25 % SBP treatment. No effect by the SBP treatment is observed on N₂0. emission, on animal production indexes such as animal weight, daily feed intake, feed conversion, and on meat quality after slaughtering.

The results are consistent with those obtained in the above in vitro fermentation example regarding the decrease of organic nitrogen mineralization and gas production. The in vivo study, however adds a new information; i.e. the fact that SBP may improve the environmental impact of animal dejections with no negative effects on animal growth rate and health. The mineral components of SBP, memories of the pristine parent natural biomaterial from which they were isolated, are likely to be important factors in animal diet and to contribute to maintain the animal productivity indexes. The same does would not occur for the SBP with reduced mineral content. These products, obtained by treating, with HC1/HF the SBP as isolated from the hydrolysis reactor (see reactions 1-3 above) , contain free COOH, PhOH, and CN groups. Such free functional groups are desirable in some cases, as in soil washing, due to the fact that they have enhanced metal sequestering capacity compared to the same groups bonded to^' the mineral part in the sourcing SBP. However, in animal diet, these same free functionalities may complex the oligo-elements which are necessary in the animal diet and make them less available for the animal metabolism. In this fashion, they are likely to cause decreased growth rate and/or negative metabolic effects in the animal.

The present invention covers a wide variety of SBP, whose composition depends on the sourcing material and on the process by which they are obtained. The expert/potential user in the field has therefore a large amount of opportunities to chose the SBP most suitable for the intended use, and so to optimize experimental conditions for best results.

Feed composition for rabbits growth study ,05 % (low SBP) e 0,25 % (high SBP) diets

Molasses 1, 50 1, 50 1,50

Calcium

0, 50 0,50 0,50 biphospate

Mineral Int. Vit. 1, 00 1,00 1, 00

SBP 0,00 0, 00 0,25

Total 100, 00 100, 00 100, 00

Use of SBP as binder to enhance cohesion and mechanical properties of feed pellets.

Table 1 ingredients, except molasses, soybean oil, vitamins and SBP, are mixed in enough quantities for the preparation of finished total 15 kg feed. The mix is divided in three aliquots. The first is used as control. The other two are added with 5 and 10 % SBP respectively. All three aliquots are made into pellets. The products are tested for resistance to compression and shear, yielding the following results:

Shear strenght: control 5.19 kg, SBP 5 % 5.78 kg, SBP 10 % 5.95 kg

Compressive strenght: control 442 newton, SBP 5 % 561 newton, SBP 10 % 505 newton.

The data, show that SBP is effective in enhancing the pellet mechanical strength. This effect would not be obtained using SBP with reduced mineral content. It is believed that the silica present in SBP is bonded to the acid and or basic functional groups of ^'the organic fraction (see reactions 1-3 above) . In this fashion, the reactivity of the mineral component is enhanced, relatively to pure silica. Thus, the mineral component can establish strong bonds with the functional groups of the other diet ingredients listed in Table 1. These bonds will enhance particle cohesion resulting in improvement of the pellet product mechanical features.

The SBP binding property is particularly effective for the manufacture of objects containing inorganic oxides, such as silica and the oxides of magnesium, titanium, calcium, aluminum e iron. With these oxides the silica bonded to the SBP functional groups will react to yield the following SBP-Si-O-M condensation products, where M is a metal atom. For example, adding SBP to a metal oxide or to a mix of different metal oxides in water suspension at 30 % suspended solid concentration, having 2-10 w/w metal oxide/SBP ratio, followed by drying, will yield a solid object which takes the form of the container in which the product preparation is carried out. This solid object, calcined at 600-800 °C, acquires greater mechanical strength than that of the same object obtained with the same metal oxides' mix, but in the absence of SBP. Use of SBP at , doses adequate to promote plant photosynthesis and increase leaf chlorophyll content, and plants growth rate and productivity.

In this example an SBP solution is used having 10.4 pH, and 14.2 % dry matter and 10 % organic matter concentration values. The example demonstrates the effect of the SBP dose applied to soil for the cultivation of red pepper.

The cultivation trial is performed according to a randomized experimental design with three replicates comprising the control soil (no SBP treatment) compared to the same soil treated with 6 SBP doses at 50, 250, 500, 1000, 2500 e 5000 kg ha^"1.

Indicators of effects on plant health and growth are plant vigor, height and diameter, and leaf chlorophyll^' content. Total and commercial fruit production, and fruit quality parameters are also measured.

The results show (Figure 1) that, compared to the control, the leaf chlorophyll content increases upon increasing the SBP dose applied to the soil up to 1000 kg ha^-1, and then decreases for higher SBP applied dose.

All plant growth and fruit production and quality indicators correlate with the leaf chlorophyll content (Figure 2) . The data demonstrate the SBP effect on chlorophyll synthesis and, consequently, on plant growth and productivity. For the specific reported example of red pepper cultivation, the data indicate an optimum dose for the effects to be highest.^'

It is believed that enhancement chlorophyll leaf production due to the soil treatment with SBP is due to the capacity of SBP to absorb light and promote water splitting which generates OH radicals. These radicals catalyze the complex photosynthesis reactions, either by the nature of the SBP organic phase and by the presence of the SBP mineral component. Particularly, Mg is essential component of chlorophyll molecular structure. Fe is known for its photo-Fenton effect. The other mineral elements are well known plant nutrients. The role of the SBP organic components may likely be due to its water solubility and capacity to keep the above inorganic elements in solution at soil pH. In this fashion the SBP would be carrier of the mineral elements in solutions and ease out their transfer from soil to the plant, where they can play their effects.

Claims

Mixture of water soluble biopolymers , said mixture comprising an organic fraction and a mineral fraction having the following composition, the organic fraction comprising polymer molecules having a molecular weight between 5 and 500 kDalton and polydispersion index between 6 and 53, the mixture containing the following amounts of carbon (C) and nitrogen (N) , expressed as % weight relative to dry matter: 37 ≤ C ≤ 65 and 3 ≤ N < 7, these elements being distributed among the following types of carbon atoms and functional groups, according to the following composition expressed as molar fraction of total organic carbon: 0.3 ≤ C_ai ≤ 0.6; CN 0.1; OMe < 0.1; 0.3 < OR < 0.6; 0.02 < OCO < 0.08; 0.07 < Ph <0.30; 0.02 < PhOH < 0.06; PhOR/Ar < 0.09; 0.04 < COOH < 0.12; CON < 0.12; C=0 < 0.05, . the mineral fraction containing the following elements, whose concentration is expressed as % weight relative to dry matter: ashes < 30; Si < 3.0; Fe < 0.9; Al < 0.8; Mg < 1.2; Ca < 6.5; K < 10; Na < 10; Cu < 0.03; Ni < 0.01; Zn < 0.05; C < 0.003; Pb < 0.01.

Process for producing a mixture of soluble biopolymers in water according to claim 1, comprising the steps of: providing a biomass or a fossil material containing an organic component;

- hydrolyzing at basic pH the biomass or the fossil material obtaining a^' residual solid phase and a liquid phase; and

separating the liquid phase by precipitating at acid pH and so obtaining a liquid phase and a precipitate, the precipitate containing the mixture of biopolymers in solid form.

Process for producing a mixture of soluble biopolymers in water according to claim 1, comprising the steps of: a. providing a biomass or a fossil material containing an organic component;

b. hydrolyzing at basic pH the biomass or the fossil material obtaining a residual solid phase and a liquid phase; and

c. separating the liquid phase by filtration through micro-, ultra-, nano-porous and dialysis membranes, preferably with molecular 5 kDalton molecular cut

. off, and so obtaining a retentate and a permeate, the retentate containing the mixture of biopolymers in solution or gel from.

Process according to claim 2 or 3, further comprising the step of subjecting the mixture of biopolymers to a further washing step with a solution at acid pH, preferably based on HC1 and/or HF, preferably at pH < 3, obtaining a mixture of biopolymers. with reduced content of mineral elements.

Process for producing a mixture of soluble biopolymers in water according, to claim 1, wherein the sourcing residual biomass is selected from different types of urban, agriculture, agro-industrial, animal and other bio-industrial origin.

Process for producing a mixture of soluble biopolymers in water according to claim 1, wherein the fossil source is selected from leonardite, peat and lignite. Process for producing a mixture of soluble biopolymers in water according to claim 2 or 3, wherein hydrolysis is performed at pH comprised between 8 and 13.

Process for producing a mixture of soluble biopolymers in water according to claim 2 or 3, wherein hydrolysis is performed at temperature comprised between 60 and 200 °C.

Process for producing a mixture of soluble biopolymers in water according to claim 2 or 3, wherein the residual solid phase (IOR) is washed with water under stirring and allowed to settle, to yield a surnatant liquid phase.

Process for producing a mixture of soluble biopolymers in water according to claim 2 or 3, wherein the surnatant liquid phase separated after settling of the insoluble residue (IOR) is added to the liquid phase separated upon completion of the hydrolysis step.

11. Process for producing a mixture of soluble biopolymers in water according to claim 2 or 3, wherein the total collected liquid phase (SOS) , separated after settling of the insoluble residue (IOR), is treated by membrane filtration of various porous^■ sizes and finally by ultrafiltration through 5 kdalton cut off membrane to produce a retentate (SOSRUF) and a permeate (SOSPUF) .

12. Process for producing a mixture of soluble biopolymers in water according to claim 2 or 3, wherein the ultrafiltration membrane retentate (SOSRUF) is diluted with water and recycled through the membrane several times, upon repeating - the dilution-filtration cycle, in . order to lower .the pH of the retentate.

13. Process for producing a mixture of soluble biopolymers in water according to claim 2 or 3, wherein wherein the total collected liquid phase (SOS) , or the ultrafiltration membrane retentate (SOSRUF) at the desired pH, are treated by ultrafiltration membranes under pressure in order to reduce the reduce the retentate volume and increase the concentration of dissolved solid matter in the retentate up to the desired level.

14. Process for producing a mixture of soluble biopolymers in water according to claim 2 or 3, wherein the membrane permeate (SOSPUF) is _. recycled to the hydrolysis reactor for washing the IOR residue or for taking up a fresh lot of residual biomass or fossil material and perform a new hydrolysis reaction.

15. Process for producing a mixture of soluble biopolymers in water according to claim 2 or 3, wherein the membrane permeate (SOSPUF) after repeated recycling to the hydrolysis reactor is enriched with organic matter, and then dialyzed to obtain an organic matter concentrate .

16. Process for remediation of soil contaminated by organic substances and/or polluting metals, comprising the steps of:

providing a water solution containing a mixture of biopolymers according to claim 1;

contacting at least once the contaminated soil with the biopolymers solution; and

separating the soil from the solution, the solution containing the organic substances and/or the polluting metals, so obtaining soil with reduce contaminant content .

17. Process for secondary treatment of washing solution recovered from soil remediation process according to claim 16, comprising the steps of:

- acidifying the recovered washing solution at pH < 4 to obtain a precipitate;

drying and burning the precipitated material to obtain- a metal concentrate to recycle for further use .

18. Process for secondary treatment of the washing solution recovered from soil remediation process according to claim 16, comprising the steps of:

filtering the recovered washing solution through micro-, ultra-, nano-porous and/or dialysis membranes to obtain a retentate and a permeate;

drying and burning the retentate to obtain a metal concentrate to recycle for further use.

19. Process for cleaning and/or lowering COD of water contaminated by organic substances and/or polluting metals, comprising the steps of:

- providing a mixture of biopolymers according to claim 1;

adding the mixture of biopolymers to the contaminated water obtaining a solution; and separating the organic substances and/or the polluting metals from the solution through precipitation or filtration through micro-, ultra-, nano-porous and/or dialysis membranes, so obtaining a retentate and a permeate, wherein the permeate is clean water for further use and the permeate is treated further; and

drying and burning the permeate to obtain a metal concentrate to recycle for further use.

20. Process for inhibiting the mineralization of organic nitrogen in anaerobic fermentation processes of a biomass, comprising the steps of:

providing a mixture of biopolymers according to claim 1;

adding the mixture of biopolymers to the biomass, the biomass being preferably as a water suspension; and

subjecting to anaerobic fermentation the biomass added with the mixture of biopolymers, so obtaining a digestate and a biogas with reduced content of ammonia.^'

16. Mixture of biopolymers according to claim 1 to be used as supplement for animal feed, the mixture of biopolymers being added to animal food to reduce the mineralization of protein nitrogen contained in the food when the food is digested by an animal, so reducing methane and ammonia in animal dejection.

17. Use of a mixture of biopolymers according to claim 1 for enhancing leaf chloropyll production, plant growth and productivity of food for humans and/or animals.

18. Use of a mixture of biopolymers according to claim 1 as binding agents in manufacturing products.

19. Use of a mixture of biopolymers according to claim 18, wherein the manufactured products contain an Organic component or a component based on inorganic oxides.