AU652085B2

AU652085B2 - A method of composting

Info

Publication number: AU652085B2
Application number: AU30137/92A
Authority: AU
Inventors: Simon Walpole Leake; Christopher Joseph Rochfort
Original assignee: GROW MIX Pty Ltd
Current assignee: Growmix Australia Pty Ltd
Priority date: 1991-12-13
Filing date: 1992-12-14
Publication date: 1994-08-11
Anticipated expiration: 2012-12-14
Also published as: AU3013792A

Description

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1 S F Ref: 225341

AUSTRALIA

PATENTS ACT 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT

ORIGINAL

Name and Address of Applicant: Grow Mix Pty Limited 102 The Northern Road Bringelly New South Wales 2171

AUSTRALIA

Simon Walpole Leake 237 Pennant Hills Road Thornleigh New South Wales 2120

AUSTRALIA

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Actual Inventor(s): Address for Service: Invention Title: ASSOCIATED PROVISIONAL [31] Application No(s) PL0019 Simon Walpole Leake and Christopher Joseph Rochfort Spruson Ferguson, Patent Attorneys Level 33 St Martins Tower, 31 Market Street Sydney, New South Wales, 2000, Australia A Method of Composting APPLICATION DETAILS [33] Country

AU

[32] Application Date 13 December 1991 The following statement is a full description of this invention, including the best method of performing it known to me/us:- 5815/3 1 -2- The present invention relates to composting and, in particular, to a process of composting which reduces production costs and utilises arboreal and garden wastes.

Existing processes of composting of garden and arboreal waste require chipping, grinding or milling of the waste, which includes sticks, branches and logs, prior to the beginning of the composting process. These requirements raise the cost of producing the compost and substantially hinder the use of garden and arboreal waste material for large scale composting.

It is an object of the present invention to provide an improved composting prl.Le s which uses garden and arboreal waste.

According to one aspect of the present invention there is disclosed a process for composting garden and arboreal waste, said process including the steps of selecting a compost bulking agent mixture of coarse material and fine material, adding mineral and/or organic nitrogen to said mixture, constructing at least one windrow of indefinite length, turning and aerating the windrow, and screening said mixture after a S period of time to produce a fine compost.

Preferably the mixture includes approximately 60% coarse material, 20 which is >20mm in its shortest dimension, 40% fine material which is in its longest dimension, and mineral and/or organic nitrogen added to the mixture at a rate of 2kg of N/cubic metre of the mixture.

Two embodiments of the present invention will now be described.

The composting process of a first embodiment requires the right blend of physical and chemical characteristics in a compost pile to give sufficient microbil activity to sustain temperatures of above 60°C for at least four weeks in windrows up to 5m high. These temperatures are required to give a very high yield of mature weed free compost fines after 8-10 weeks. These fines are of commercial value as fertilisers and i 30 soil improvers.

The process of composting includes the steps of visually selecting unmilled garden and arboreal waste so that the compost bulking agent mixture is 60% coarse material, which includes sticks, branches and logs, and 40% fine material, such as leaves, grass clippings and humus.

Preferably the mixture includes approximately 60% coarse material, which is >20mm in its shortest dimension, 40% fine material which is <20mm in its longest dimension. The use of the coarse or unmilled garden and arboreal waste not only allows for the construction of larger aerobic amg/0604y -3piles; hence saving considerable space, minimising heat, drying and nitrogen losses; but disposes of this waste material in a much more inexpensive way than is presently possible.

The next step of the process is to add mineral and/or organic nitrogen to the compust bulking agent mixture at a rate of 2kg/cubic metre. A layer of bulking mixture is laid on a mixing area and the nitrogen source is spread over its surface and immediately covered with a further layer of bulking agent mixture and so on, in layers until a windrow 3-5m high and indefinite length is made. Water is added to bring the moisture level up to 40-55% w/w.

The windrows are turned and aerated weekly with a modified front end loader and the windrows reconstructed so as to leave a path wide enough for the front end loader to be used.

After approximately 10 weeks composting, the material in the compost windrows is screened through 20mm sieves and a fine compost is ready for sale and further processing.

It is believed that the process yields about 800-1000 cubic metres 0 of usable high nutrient compost, and 200 cubic metres of screenings wood) per 20C cubic metres of fresh arboreal and garden waste. The differences in the yields to the component materials is due to volume losses in composting and oversize screenings. The material which is screened by the oversized screenings can be used to blend with fresh waste to obtain the right physical properties or be further processed in other ways.

The advantages of the compost processing as described herein include reduced production costs by about 50% and that a waste product which is free, is utilised to produce a valuable fertillser and soil improver commodity. Public utilities can save in relation to disposal I costs of the waste as the waste can be used to produce the compost. Tilhe C 30 present technology does not allow for the low production cost necessary to make use of large volumes of arboreal and garden waste feasible.

The process as described requires and indeed necessitates no processing such as: chipping, grinding, or milling, of the bulking agent mixture except to allow some shredding to reduce the volume for economic transportation, resulting in low manufacturing costs. All existing technologies rely on such processing. Such processing which is carried out to reduce volume must not result in <60% of material passing a screen.

amg/0604y -4- The process allows the construction of larger aerobic windrows than is currently possible hence allowing more material to be processed per hectare than is currently possible (volume increases as the square of dimension of the windrow).

The process results in a higher content of available plant nutrients in the resulting compost because chipping does not occur, and coarse, low nutrient wood is removed by screening hence concentrating nutrients in tthe fine compost material.

y Liises The process^Ar quires the addition of 2kg of nitrogen per cubic metre of bulking agent mixture, in addition to any nitrogen already in the bulking agent mixture. The bulking agent mixture is selected such that the total nitrogen content is not over 1% w/w. The added nitrogen can be mineral and/or organic or a combination of both, thus allowing for the use of non-toxic waste materials to be consumed by the process.

Non toxic industrial wastes such as waste gypsum plaster, Jute processing fines, etc. can be selected and added to the mixture which is then composted long enough such that the final compost material falls within the following chemical parameters.

pH 6.5 to r 20 EC by AS 3743-1989 1.0-2.0 Cation ratios- of Cation Sum Sodium Potassium 10-30 Calcium 50-70 Magnesium 10-20 Ammonium <2 Nitrite absent Germination Assay by AS 3743-1989 In a second embodiment, the process is used to process putrescible food and agricultural wastes into a compost form and will be further described as follows- :i The mixture is laid down in alternative layers of bulking agent/food waste, finishing with a windrow having a top layer of bulking agent. The windrow is not turned for 2 days which allows time for the odour of putrescible food waste to be completely destroyed in the highly aerobic composting environment. If the windrow is turned after this time, no obnoxious odours will result.

When using liquid food WL'tes where the moisture holding capacity ag/604 f' amg/0604y l^ of the windrows can be exceeded before the required N content is reached, several additions of the bulking agent mixture can be made. These additions cause intense heating in the windrow allowing rapid evaporation of the excess water. Such further additions must cease at least 4 weeks before termination of the composting, to allow compost maturity to be reached as described by the chemical parameters above.

The foregoing describes only two embodiments of the present invention, and modifications obvious to those skilled in the art can be made thereto without departing from the scope of the present invention.

i l 0 i 130 amg/0604y

Claims

1. A process for composting garden and arboreal waste, said process including the steps of selecting a compost bulking agent mixture of coarse material and fine material, adding mineral and/or organic nitrogen to said mixture, constructing at least one windrow of indefinite length, turning and aerating the windrow, and screening said mixture after a period of time to produce a fine compost.

2. The process as claimed in claim 1, wherein the selected mixture of compost bulking agent is: approximately 60% coarse material which is greater than approximately 20mm in its shortest dimension; and approximately 40% fine material which is less than approximately 20mm in its longest dimension.

3. The process as claimed in claim 1 or 2, wherein the mineral and/or organic nitrogen is added to the mixture at a rate of 2kg of nitrogen per cubic metre of the mixture.

4. The process as claimed in any one of the preceding claims, wherein said process further includes the steps of laying a first layer of said mixture, laying a first layer of said mineral and/or organic nitrogen on said first layer of mixture, then laying alternate layers of said mixture and said mineral and/or organic nitrogen, until said windrow is approximately 3-5 metres high.

The process as claimed in claim 4, wherein water is added to said windrow to raise the moisture level to approximately 40-55% w/w.

6. The process as claimed in claim 5, wherein said windrow is turned and aerated approximately once every week.

7. The process as claimed in claim 6, wherein said windrow is o screened through 20mm sieves after approximately 10 weeks.

8. The process as claimed in any one of the preceding claims, wherein said fine material includes putrescible food and agricultural waste.

9. A process for composting garden and arboreal waste, said process being substantially as described with respect to either one of the two Examples. DATrED this FOURTEENTH day of DECMEBER 1992 Grow Mix Pty Limited Simon Walpole Leake Patent Attorneys for the Applicants SPRUSON FERGUSON amg/0604y A Method of Composting -ABSTRACT- A process for composting garden and arboreal waste is disclosed. The process includes the steps of selecting a mixture of compost bulking agent of coarse material and fine material, adding mineral and/or organic- nitrogen to the mixture, constructing at least one windrow of indefinite length, turning and aerating the windrow, and screening the aerated mixture after a period of time to produce a fine compost. The fine material can include putrescible food and agricultural waste. o n *3 I! amgl/OS04y