WO2008135845A1

WO2008135845A1 - Bag for the collection of organic waste and method for its manufacturing

Info

Publication number: WO2008135845A1
Application number: PCT/IB2008/001103
Authority: WO
Inventors: Gianluca Bianchi; Matteo Benedusi; Lorenzo Altheimer
Original assignee: T.T.B.S. Llc
Priority date: 2007-05-08
Filing date: 2008-05-05
Publication date: 2008-11-13
Also published as: ITMI20070921A1

Abstract

This invention relates to bags for the collection of organic waste, whose inner surface, which comes into contact with the waste material, carries a mixture of bacteria and fungi that synergically activate the breakdown of the organic substrate, thus promoting the composting process.

Description

BAGS ACTIVATING THE ORGANIC WASTE DECOMPOSITION

This invention relates to organic waste collection systems in general. More specifically, the invention relates to organic waste collection bags whose inner surface, which comes into contact with the waste material, is treated with a mixture of bacteria and fungi that synergically activate the breakdown of the organic substrate, thus promoting the composting process. The bags may be made of paper or another biodegradable material, and may have an inner film or a coating to which the micro-organisms are applied.

Introduction

The term composting, according to current usage, indicates a series of biological phenomena that combine to convert complex organic matter to more or less simple substances (carbon dioxide, water, humus and mineral salts). Bacteria, actinomycetes and fungi, which are the micro-organisms responsible for the humidification process, use active enzymes to break down the complex organic substance for their own nutrition; the resulting metabolic derivatives are more easily assimilated by the medium, and this process ensures complete, rapid recycling of the starting waste.

Composting is an aerobic process which takes place in three main stages:

1. biochemical breakdown by hydrolytic enzymes; 2. biological transformation;

3. maturing.

At the first stage (thermophilic), which must obviously be very rapid and intense to prevent anaerobiosis, energy is released in the form of heat; the temperature exceeds 6O⁰C (and for optimum composting should exceed 65°C). At this stage, which lasts about a month and is the limiting stage of the entire process, there is high oxygen demand and temporary formation of intermediate breakdown compounds (acetic, propionic and butyric acid) which are toxic to plants (the compost therefore cannot be used at this stage), but rapidly metabolised.

At the second stage (40-45⁰C), the intensity of the metabolic processes declines; in addition to bacterial activity other activity takes place due to various species of fungi and actinomycetes that break down starch, cellulose and lignin, which are important for the synthesis of humic substances. At this stage, oxygen demand considerably decreases, and the organic substance is sufficiently stable and consequently no longer has a toxic effect on plants. The compost already has the typical odour of fresh potting compost at this stage; actinomycetes play an important part in this process, because they produce aromatic compounds typically present in soil. The third stage of the process is characterised by intense colonisation by small animals (such as earthworms), which help to break up and mix the organic compounds and minerals formed. Industrial composting

Industrial composting uses structured mechanisation to minimise the time taken to obtain mature compost. Composting is a natural process and can therefore be optimised, not so much from an instrumental as from a purely biological standpoint, by accelerating the organic substance maturing processes that take place spontaneously in nature.

There are numerous examples of spontaneous composting in nature, such as the decomposition of forest litter and ripening of manure, which latter process is practised by numerous farmers. The only problem with spontaneous composting is that the transformation times are generally too long to meet the requirements of an industrial system. Nowadays, it is possible to optimise all the natural composting processes with technical/practical methods (use of bacterial/enzymatic accelerators, colonies of selected bacteria that directly affect the speed of the process, turning with mechanical shovels, maturing times, etc.) which reduce the time taken to obtain mature compost, and produce high-quality compost with added value. Home composting

This practice is used in the management of the "ecological home". In this case it is important to sieve the matrices used before home composting. Recycling of selected organic materials reduces foul-smelling emissions. This practice also reduces the volume and weight of the non-organic waste placed in the bin, thus achieving economies on waste disposal rates (the organic matter in untreated waste accounts for 30-50% of the total). The compost obtained, though not standardised, can be considered a useful soil conditioner for the home flower or vegetable garden. The use of good bacterial/enzymatic process accelerators is also essential for domestic composting, in order to optimise the process. Rural composting

Composting has always been practised on farms to return some of the organic matter used for crop growing to the soil, such as ripening manure and digging in plants after the harvest. On farms, maturing of substances in heaps is designed to stabilise and humify the organic substance, in order to eliminate waste. Composting provides two benefits: eliminating one type of waste and reducing the cost of fertilising soil. Composting can be performed on an industrial scale (collection and ripening of manure and plant waste of various origins), and by individual farms, with qualitative differences due to the different starting mixtures of substrate.

Standardisation of the industrial composting method has developed a "closed" processing system, which is carried out in rooms under vacuum, from the time of waste disposal to the packaging of the end product. All the problems associated with disposal of the percolate are dealt with by purification or removal, while unpleasant odours are reduced by elimination with an air scrubber and absorption with a biofilter. Treatments with additives are also performed in a closed environment during the creation of compost heaps, using dedicated labour and/or machinery to guarantee thorough dispersal of the additives in the mass to be composted.

This system involves high overall plant management costs. DESCRIPTION OF THE INVENTION

This invention relates to a bag made of biodegradable material, preferably cellulose or bio-plastic (in particular Mater-Bi®), designed for the collection of organic waste and characterised in that its inner surface is treated with a mixture or combination of micro-organisms (in spore or vegetative form) able to activate the breakdown of organic material.

In a preferred embodiment thereof, the combination comprises at least four, preferably at least six, and even more preferably all eight of the following species of bacteria and fungi:

Bacillus Subtilis: gram-positive, mesophilic and aerobic, produces endospores which are highly resistant even in environments that not are very favourable to biological development, and produce a wide variety of enzymes (protease and beta-glucanase) specific for sugars and starches;

Bacillus licheniformis: gram-positive, mesophilic, anaerobic and spore-forming, produces protease, amylase and lipase, specific for the breakdown of fats, resistant in environments with high concentrations of NaCI

(up to 7%), denitrifying activity in anaerobic circumstances, and also develops at high temperatures (up to 50⁰C);

Bacillus megaterium: gram-positive, mesophilic, aerobic and spore- forming, produces α and β-amylase enzymes specific for the breakdown of starches and protease for casein, resistant in environments with high concentrations of NaCI (up to 7%);

Bacillus polymyxa: gram-positive, mesophilic, anaerobic, spore-forming, produces cellulase and hemicellulase specific for the breakdown of cellulose and paper; nitrifying activity;

Bacillus circulans: gram-positive, mesophilic and facultative anaerobic, spore-forming, produces protease, chitinase and pectinase, enzymes specific for the breakdown of plant, fibre and paper derivatives, resistant to high temperatures (up to 50⁰C);

Aspergillus niger. eukaryote, filamentous, facultative anaerobic, spore- forming, saprophytic, composter;

Aspergillus orizae: eukaryote, filamentous, facultative anaerobic, spore-forming, osmotrophic, starch-demolishing; Lactobacillus acidophilus: gram-positive, probiotic, anaerobic and spore-forming, produces lactase, vitamins B and K and acidophiline, specialises in the breakdown of vegetable matter, resistant to high temperatures (up to 45°C) and to an acid environment (up to pH 4).

The combination of micro-organisms listed above possesses a highly synergic breakdown effect on the organic substrate in household or vegetable waste, and therefore constitutes a particularly preferred embodiment of the invention. The following additional combinations were selected for their breakdown capacity, and therefore also represent preferred aspects of the invention: a) B. subtilis, B. Polimyxa, Asp. niger, Asp. Orizae; b) B. subtilis, B. megaterium, B. polymyxa, lactobacillus, Asp. niger, Asp. Orizae; c) B. subtilis, B. licheniformis, B. circulans, Asp. niger, Asp. orizae; d) B. licheniformis, B. circulans, lactobacillυs, B. polymyxa, Asp. niger, Asp. Orizae.

These combinations have proved particularly suitable to accelerate and optimise the natural reaction that creates high-quality compost from the organic matrices of organic waste.

The quantities of each micro-organism present in the mixture can vary within the following ranges:

B. subtilis from 15 to 30%,

B. licheniformis from 10 to 20%, B. megaterium from 10 to 20%,

B. polymyxa from 15 to 30%,

B. circulans from 10 to 20%,

Aspergillus niger from 10 to 25%,

Aspergillus orizae from 10 to 25%, Lactobacillus acidophilus from 10 to 20%.

The micro-organisms can be applied to the inner surface of the bag according to the invention by spraying a solution or liquid suspension of bacteria and/or fungi in a suitable solvent, preferably in an aqueous solvent, possibly with the addition of co-solvents, dispersing agents or stabilisers, tonicity modifiers, pH regulators and the like.

A concentration of approx. 1 billion bacterial and fungal cells per ml of solution or suspension is enough to ensure optimum application of the product to the paper used to make the bags. It has been observed that the biodegradation activity of the paper medium maintains unchanged, even if it is stored in the warehouse for long periods (over 12 months).

The bacteria, fungi and/or their spores deposited on the paper become active in contact with the moisture and liquid phase of the waste, and trigger the process of biological breakdown (composting) of the organic pollutants. The bacteria activated produce enzymes which penetrate deeply into the organic agglomerates present, promoting their decomposition. In particular, the combined effect of the different micro-organisms:

- inhibits putrefactive fermentation - prevents the emission of volatile substances which are useful for the final compost but unpleasant for residents living near the works

- allows the percolate to be recovered and reintroduced into the manufacturing cycle as a humidifying agent.

Another aspect of the invention therefore relates to the use of a bag as described above for the collection of organic plant and household waste. The immediate financial advantages deriving from the use of said breakdown system are:

- a reduction in the handling required for the treatments;

- a reduction in the air volume that needs to be changed in the composting tunnels;

- up to a 15% reduction in the time taken for the compost to mature;

- immediate availability of compost without any additional investments; moreover, this method does not require new structures, because the bacterial/fungal mixture is inoculated on entry of the organic waste to be composted.

EXPERIMENTAL PART

The following mixture of micro-organisms was used:

Bacillus subtilis (ATCC 6051), Bacillus licheniformis (ATCC 12713), Bacillus megaterium (ATCC 14581), Bacillus Polymyxa (ATCC 842), Bacillus Circulans (ATCC 9500), Aspergillus Niger (ATCC 1015), Aspergillus Orizae (ATCC 1011); Lactobacillus Acidophilus (ATCC 4356).

ATCC = "American Type Culture Collection" Virginia, USA. APPEARANCE: opaque liquid

COLOUR: yellow pH: 8.2-8.8

DENSITY: 1000-1025 g/cm3 STABILISER: propylene glycol

CFU/ml: 100 x10^?

SECURITY: there is no risk, even in the event of improper use such as swallowing, handling or contact.

FORMULA: BATP L1700C APPLICATION OF BATP L1700C TO THE BIODEGRADABLE PAPER

OR PLASTIC MEDIUM:

The product is sprayed on. The spraying apparatus is installed at the end of the paper works, where the finished paper is rewound, or inside the biodegradable plastic tube before the folding and cutting of the bag. The spray application system contains nozzles which, according to the speed of the machine, spray a quantity of the product sufficient to cover the entire length of the final roll.

The nozzles operate with two converging jets, one of compressed air and the other of the bacterial product, to create a jet consisting of particles with a mean diameter of under 10 microns. The system includes a storage tank for the bacterial product under agitation, a feed pump, 1-5 spray nozzles, depending on the opening and speed of the machine (conversion unit or rewinder), a screen that conveys the jet into the two layers, management software and a system that controls the quantity supplied on the basis of the rpm of the machine (acceleration or slowing of the speed of the machine), Two types of bag have been made, one with bioactive paper, called the Bio-Active Biodegradable Bag, and the other with Mater-Bi® (made from corn starch), called the Eco Bag. Method for determining the biodegradability of the bag.

This experimental test is designed to demonstrate that the Bio-Active Biodegradable Bags have a significantly greater ability to biodegrade over time than bags made from conventional materials. The experimental conditions used for this test simulate real composting conditions. After three weeks, the material of the Bio-Active Biodegradable Bags should have broken down to such an extent that it can no longer be detected visually or in the sieve compared with laboratory compost material, whereas the untreated bags remain perfectly identifiable in the compost heap.

Materials and methods

1) The bags must be cut into pieces approximately 1 cm square to simulate the effect of the crusher on entry to the composting plant

2) an organic substrate must be prepared in the laboratory which simulates the waste that normally makes up the organic phase of the compost. Said substrate consists of: 23% wood flour 15% soya flour 25% flower compost 15% dry cat food

5% seed oil 15% drinking water 2% of the material used to make each type of bag tested

3) Distribute 200 g of prepared organic substrate between 8 trays of equal size

4) Mark 2 trays as Biodegradable Bio-Active Bag (BIO) and 2 as untreated paper (NT), 2 as biodegradable Bio-Active Eco Bag (ECO) and a similar untreated one (ECO NT) 5) place the trays in a stove thermostated at 40⁰C, stir the substrate on alternate days, possibly adding water if the substrate is too dry, and check the weight of the material, which must remain at 200 g

6) Periodically (twice a week) record the differences observed in terms of:

1. consistency of substrate,

2. absence of unpleasant odours

3. absence of mould formation

4. breakdown of paper

7) assign a score to each parameter observed, chosen with the following criteria:

0= poor (= no change from the initial conditions)

1 = slight (= minimal variations on the initial conditions)

2 = moderate (= evidence of biological activity)

3 = good (= significant evidence of biological activity)

4= excellent (= very significant evidence of biological activity)

8) After 21 days' observation, analyse the results obtained. Comparison of paper bags

Parameter: Consistency of substrate

Mean values

* increase in unpleasant odours Parameter: No mould formation

Parameter: Breakdown of paper

The results are illustrated in Figure 1. Comparison of bags made of Mater-Bi Parameter: Consistency of substrate

Parameter: No unpleasant odour

^* increase in unpleasant odours Parameter: No mould formation

Parameter. Breakdown of Mater-Bi

The results are illustrated in Figure 2.

COMMENTS

To express the quality of the compost and consequently determine the efficacy of the Bio-Active Biodegradable Bags, 4 main qualitatively observable parameters have been identified. For each parameter, a score of O to 4 was allocated to express the measurement of the observation made during the established period of 21 days. The results for the 4 treatment groups were analysed (calculated mean) and displayed in chart form to allow direct comparison.

Substrate Consistency parameter: the Bio-Active Biodegradable Bags already showed significant evidence of effective biological activity by the 10th day of observation, whereas the untreated paper bags and Mater-Bi bags did not differ significantly from their original state.

Absence of Odour parameter: no unpleasant odours developed in the compost with Bio-Active Biodegradable Bags, whereas a pungent concentration of sulphides developed in the compost with NT materials.

Absence of Mould Formation parameter: no abnormal mould formation was observed on the surface of the compost with Bio-Active Biodegradable Bags, whereas uncontrolled mould formation was evident in the compost with both NT materials by the 10th day, and worsened with time.

Material Breakdown parameter: the pieces of Bio-Active paper and ecoplastic break down until they are invisible by the 14th day, whereas the process is significantly slower in the presence of NT materials.

In this laboratory test, both types of Bio-Active bag demonstrated considerable efficacy in accelerating the process of composting the organic fraction, keeping the organoleptic characteristics of the compost under control, preventing the formation of unpleasant odours typical of uncontrolled fermentation and the formation of moulds that interfere with bacterial activity, and above all accelerating the biodegradation processes of the cellulose and lignins present.

The other 4 mixtures of bacterial strains and fungi identified, whose composition meets the requirements specified above, also underwent the same laboratory tests:

MIXTURE A: B. subtilis, B. polymyxa, Asp. niger, Asp. Orizae; MIXTURE B: B. subtilis, B. megaterium, B. polymyxa, Lactobacillus,

Asp. niger, Asp. Orizae;

MIXTURE C: B. subtilis, B. licheniformis, B. circulans, Asp. niger, Asp. orizae;

MIXTURE D: B. licheniformis, B. circulans, Lactobacillus, B. polymyxa, B. polymyxa, Asp. niger, Asp. Orizae.

The method of application to the paper substrate, the experimental conditions, the materials used to simulate the composting process and the method of evaluating the activity of the various mixtures are the same as used to demonstrate the efficacy of the Bio-Active Biodegradable Bag. Results

Comparison of paper bags with Mixture A Parameter: Consistency of substrate

Mean values

Parameter: No unpleasant odour

Mean values

Parameter: No mould formation

The results are illustrated in Figure 3. Comparison of paper bags with Mixture B Parameter: Consistency of substrate

Mean values

Parameter: Breakdown of paper

The results are illustrated in Figure 4. Comparison of paper bags with Mixture C Parameter: Consistency of substrate

Mean values

The results are illustrated in Figure 5. Comparison of paper bags with Mixture D Parameter: Consistency of substrate

Mean values

The results are illustrated in Figure 6.

COMMENTS

In this second laboratory test, performed under the same conditions as the first, the results obtained from the comparison of the 4 bacterial mixtures

A, B, C and D and the optimum bacterial mixture identified for the manufacture of the Bio-Active Biodegradable Bag (BIO) demonstrate the ability of each mixture examined to accelerate the composting process.

Claims

1. Bag for the collection of organic waste, made of biodegradable material and characterised in that its inner surface carries a combination of micro-organisms, in vegetative and/or spore form, which are able to activate the breakdown of organic matter.

2. Bag as claimed in claim 1 , wherein said biodegradable material is chosen from cellulose and bioplastic derived from starch.

3. Bag as claimed in claims 1-2, wherein said combination of micro- organisms includes at least four, preferably at least six, and more preferably all eight of the following micro-organisms

Bacillus subtilis, Bacillus licheπiformis, Bacillus megaterium, Bacillus polymyxa, Bacillus circulans, Aspergillus niger, Aspergillus orizae, Lactobacillus acidophilus.

4. Bag as claimed in claim 3, wherein said combination is selected from the group comprising: a) B. subtilis, B. polymyxa, Asp. niger, Asp. Orizae; b) B. subtilis, B. megaterium, B. polymyxa, Lactobacillus, Asp. niger, Asp. Orizae; c) B. subtilis, B. licheniformis, B. circulans, Asp. niger, Asp. orizae; d) B. licheniformis, B. circulans, Lactobacillus, B. polymyxa, B. polymyxa, Asp. niger, Asp. Orizae.

5. Bag as claimed in claim 3, wherein said combination is as follows: Bacillus subtilis, Bacillus licheniformis, Bacillus megaterium, Bacillus polymyxa, Bacillus circulans, Aspergillus niger, Aspergillus orizae,

Lactobacillus acidophilus.

6. Bag as claimed in claims 3-5, wherein the quantity of each microorganism varies within the following ranges: B. sυbtilis from 15 to 30%, B. licheniformis from 10 to 20%, B. megaterium from 10 to 20%, B. polymyxa from 15 to 30%, B. circulans from 10 to 20%,

Aspergillus niger from 10 to 25%, Aspergillus orizae from 10 to 25%, Lactobacillus acidophilus from 10 to 20%.

7. Method for the manufacture of a bag as claimed in any of the preceding claims, wherein a solution or liquid suspension of micro-organisms in a suitable solvent is sprayed onto the inner surface of the bag.

8. Method as claimed in claim 7, wherein said solvent is water.

9. Method as claimed in claim 7, wherein said solution and/or suspension contains at least a billion cells of the micro-organism.

10. Use of a bag as claimed in claims 1-6 for the collection of plant and household organic waste.