Field of Invention

The invention relates to combating unpleasant smell emitted from garbage containers. More particularly, the inven¬ tion relates to a composition for addition to garbage s containers for combating obnoxious odour emitted therefrom and for temporarily reducing the bacterial activity in the garbage and thereby the putrefaction of putrefiable components of the garbage. The invention further relates to an embodiment of said composition which additionally is effective in very sig- 0 nificantly reducing or eliminating the spreading of infectious microorganisms from garbage containers through insects.

The technical background

The technical literature contains little of interest s for solving the problem which the present invention concerns. Attempts have previously been made with addition of special composting bacteria and/or various chemicals to garbage con¬ tainers by means of sprinkler systems. Further, various mechanical solutions have been tested, like cooling of the 0 garbage, use of special fan systems for driving off bad smell, and use of tight garbage containers combined with mechanical air purification filters. However, none of these attempts at solving the problem which concerns combating bad smell emitted from garbage containers have gained general 9 acceptance, be it because they were too expensive, too complicated or did not answer the necessary requirements to the degree of efficiency of the solution.

Objects of the invention it is an object of the invention to provide a composition for combating obnoxious odour emitted from garbage containers, the composition having to be environmentally ac¬ ceptable, cheap enough to be of interest to the consumers, simple to produce and very simple to use. The composition should efficiently combat the emission of obnoxious gases from garbage containers and should not have the deficiencies suf¬ fered by previous attempts at solving this problem. According to one embodiment of the composition of the present invention it should in addition efficiently combat insect activity in or

around garbage containers.

Brief description of the invention

The above-mentioned objects are fulfilled according to the invention by a composition for combating bad smell from garbage containers, the composition being characterized therein that it comprises water insoluble granulates having large inner surface and being capable of absorbing moisture due to strong capillary effect, and one or more hypochlorite compounds. According to an embodiment of the present composition it additionally comprises a substance which in combination with the hypochlorite compound acts as a strong repellent to insects.

As granulates granulated fossil diatomaceous earth is preferably used which has been subjected to special treatment at very high temperature such that the inner surface of the granulates is very large. The heat treatment may for example have been carried out at about 1350 "C.

The size of the granulates is preferably 0.5-3 mm, e.g. 1-3 mm, and these specially treated granulates of diatomaceous earth do not form lumps upon contact with mois¬ ture, and they have a quite enormous inner surface making them capable of sucking up as much as 126 % moisture based on the weight of the granulates per se. Moreover, such granulates are very cheap. A suitable type of granulate for the composition according to the invention is sold under the trade mark "Absodan".

As hypochlorite compounds alkali metal and/or alkaline earth metal hypochlorites are preferably used, in particular sodium hypochlorite in aqueous solution or solid calcium hypochlorite, preferably granulated.

Sodium hypochlorite in aqueous solution is stable so that there is no risk of unintentional spontaneous reactions when using such sodium hypochlorite solutions, and, moreover, such solutions are very cheap which, of course, is of essen¬ tial importance to the user.

Also calcium hypochlorite is sufficiently stable for the objects according to the invention and, moreover, is a cheap chemical.

As repellant (= insect repellent substance) naphthalene in the form of a powder or in the dissolved state is a suitable active compound to use in combination with the hypochlorite compounds mentioned above. Separately none of the compounds exhibits the desired insect repellent properties to a sufficient degree. The same may be said about the following organic substances which are examples of insect repellent substances which can be used in the present composition: a) Camphor in the form of camphor oil (The Merck Index, Centennial edition 1989, substance No. 1738). The substance may be dissolved in a solvent, e.g. fat prior to the addition. One may also use it in the form of white camphor oil. b) Citronella oil (aromatic oils with marked lemon fragrance). c) Dissolved pine resin (This substance gives a very pleasant fragrance and functions well in the intended manner. It makes the addition of a separate fragrant substance, like e.g. pine needle oil, superfluous). d) Citric acid dissolved in water. (Slightly weaker effect than the other mentioned substances in the same concentration, however, cheaper).

Of the substances narrated above pine resin appears to be the overall best and cheapest alternative. These alter¬ native substances may be used as complete or part substitution for naphthalene in the present compositions and also in approximately the same concentrations by weight as naphthalene.

Detailed description of the invention with best embodiment

Investigations made by the inventors of the invention claimed herein showed that a significant part of the problem of obnoxious odour connected with garbage containers is due to fly larvae. They give off an intense and very nauseating smell which often drowns the actual odour from the garbage. Moreover, insect activity in and around garbage containers

represents a considerable danger for the spreading of infec¬ tious microorganisms from the containers. Because flies are primarily attracted by the gases produced by the putrefaction process in the garbage, it was according to the invention 5 aimed at reducing the activity of putrefaction bacteria in the garbage and thereby the development of gas therefrom. However, because the further degradation of garbage stored in con¬ tainers after emptying frequently takes place at land deposits and not in combustion furnaces reduction of the bacterial o activity would preferably have to be temporary in order to prevent the putrefaction from coming to a halt at land deposits. It was a further requirement that the composition according to the invention should not unacceptably burden the environment. s Trickle of moisture from garbage in a container also represents a substantial problem. A significant portion of this trickle is accumulated in the containers, and bacteria are thriving very well in such trickle. Accordingly, it was found to be of essential importance to be able to absorb the o trickle of moisture in order to prevent a too strong bacterial growth.

The compositions according to the invention meet the above requirements to efficient compositions for combating insect activity and obnoxious odour emitted from garbage con- 5 tainers by being capable of absorbing large amounts of mois¬ ture per unit volume. Further, the composition may take part in/activate reactions which modify obnoxious gases, and it can temporarily reduce the bacterial activity in the garbage. Moreover, the combined effect of insect repellent substance 0 and hypochlorite compounds provides the composition with outstanding insect repellent property. Environmentally the composition is completely acceptable and it is a cheap composition. Further, the composition is simple to produce and simple to use. 5 The two main compositions according to the present invention, i.e. specially treated diatomaceous earth granulates together with an aqueous sodium hypochlorite solution or together with solid calcium hypochlorite, optionally with insect repellent substance, may be used in

highly varying amounts with respect to the amount of garbage, and in each case the consumption will be determined by the least amount, with respect to the amount of garbage, which gives a significant reduction of the obnoxious odour emitted and insect activity.

Experiments have shown that suitable amounts of diatomaceous earth granulates and calcium hypochlorite for treatment of refuse or garbage of average composition from households in a large garbage container which may have a volume varying from 2 to 15 m ³ , e.g. 11-15 m ³ , are 1-6 liters of diatomaceous earth granulates, more normally 2-3 liters, per container and 15-20 g calcium hypochlorite and, optional¬ ly, 1-2 g insect repellant per liter diatomaceous earth granulates, e.g. when using 3 liters of diatomaceous earth granulates in a large garbage container 45-60 g calcium hypochlorite and, optionally, 3-6 g insect repellant will nor¬ mally be added. However, the tolerable limits are astonishingly wide, and because higher temperatures lead to the active components becoming more easily decomposed, this formulation covers all normal cases and requirements within a broad spectrum. The practical use of a such composition for combating insect activity and obnoxious odour is to spread the mixture of diatomaceous earth granulates, insect repellant and calcium hypochlorite across the bottom of a container when the latter is empty.

If an aqueous sodium hypochlorite solution is used together with the specially treated diatomaceous earth granulates, a normal addition of sodium hypochlorite solution will be 0.1-0.2 liters of 10-15 % sodium hypochlorite solution per liter of specially treated diatomaceous earth granulates. Again the tolerable limits are wide, and for each case the necessary amount of the composition for combating insect ac¬ tivity and obnoxious odour which must be added to garbage containers in order to reduce or completely stop the emission of obnoxious odour and repel insects will vary with the com¬ position of the garbage and with the amount of garbage in the container. However, a good guideline for the necessary amount of addition of the composition according to the invention is that it should be within the range of 1-6 liters of granulate

for a filled garbage container having a volume of 2-15 m ³ . In addition to combating obnoxious odour and repel insects from garbage containers it may for some markets also be desirable that the composition according to the invention gives off its own pleasant perfume odour, and for example pine needle odour has been found to be a good masking odour for hypochlorite solutions.

The calcium hypochlorite embodiment of the composition according to the invention is best suited for big users whereas the sodium hypochlorite embodiment of the composition according to the invention is best suited for com¬ mon household use. Accordingly, it is advantageous that the sodium hypochlorite variant of the composition according to the invention be packed as consumer unit in closable packages, e.g. in a plastic bottle with wide neck. The user then employs so much of the composition as is required at any time and then closes the package tightly.

None of the two embodiments is reactivatable, and because the decomposition products of the hypochlorites essen- tially are calcium chloride respectively sodium chloride, oxygen and water, and as the optionally used insect repellant is not considered harmful for the environment, the compositions according to the invention are also environmentally safe to use. With respect to the active components of the composition according to the invention, i.e. the hypochlorite compound, particularly sodium hypochlorite or calcium hypochlorite, and the insect repellent substance, e.g. naphthalene, the required dosage were established through about 250 tests. The dosage limits were partly established by means of scraping off bacteria from the container walls and the container floors with subsequent counting of cultures in counting chambers, partly by means of direct measurements of the gas development, partly by measuring the activities of the flies about and in the containers, and finally by measuring the number of fly larvae upon emptying the containers. All measurements were evaluated in relation to the outside temperatures. Based on these measurements, the product variants were adjusted so that they would optimally fulfil the

requirements which normally will be set to the products.

The composition according to the invention has been tested both in small scale and in large scale. By the test in small scale each garbage container was provided with fly paper around the opening and inside the container for direct measurement of the activity of the flies. The containers were placed so far away from one another that they could not influence one another in any way, and care was taken that there were as equal sun/shadow and temperature conditions as possible. The composition according to the invention was sprinkled evenly across the bottom of the empty container before filling it with the garbage.

When using specially treated diatomaceous earth granulates together with sodium hypochlorite solution and naphthalene the fly activity round about the test containers was reduced almost to nil. The bacterial activity was also significantly reduced, however, it did not stop completely. The development of gas was under most conditions reduced by nearly 75 %, and the gas produced was modified by liberated OCl'-ions/chlorine ions so that the result was a fresh, clean odour emitted from a full container as well as an empty con¬ tainer.

The combination of granulated calcium hypochlorite, naphthalene and specially treated diatomaceous earth granulates gave exactly the same results as the combination of specially treated diatomaceous earth granulates, naphthalene and sodium hypochlorite solution. However, the duration of the effect obtained with granulated calcium hypochlorite was higher (increased by about 40 %). Moreover, at a relatively late stage of the tests it was found that calcium hypochlorite was superior compared with sodium hypochlorite during strong cold. Under such conditions the sodium hypochlorite/diatomaceous earth granulates lost much of their effect whereas the calcium hypochlorite variant retained its effect substantially unchanged. This relates to bad smell emitted only, as insect activity under such cold conditions is of course substantially nil in any respect. On the other hand, the sodium hypochlorite variant is a cheaper and more simple solution and, moreover, it was easier to add fragrance thereto

for use indoor.

The composition according to the invention has also been tested under more realistic and difficult conditions. A series of large garbage containers was selected 5 which were directly influenced by sunshine. The containers were selected because the garbage stench therefrom had caused especially significant problems for a hospital over a number of years. The testing of the compositions was carried out on 36 large garbage collection containers under varying con- o ditions. As previously, the composition according to the invention was sprinkled across the bottom of the garbage con¬ tainers before filling these with garbage.

The result was that as garbage was filled into the containers, the containers which previously had been very s troublesome did not now emit any stench of garbage at all but instead had a fresh smell of chlorine. At the same time, the insect activity in or near the containers was reduced to near nil.For each single container the dosage of the composition was about 5 liters of diatomaceous earth granulates on the o bottom of each container in admixture with naphthalene and sodium hypochlorite solution and solid calcium hypochlorite respectively. These two variants seemed to be of equal value in all respects, however, it was found that the calcium hypochlorite variant retained its effect longest, particularly 5 during cold conditions, e.g. from 0 "C to -25 "C.

With regard to use indoor in smaller scale, for com¬ mon households, it became clear that the sodium hypochlorite variant, suitably with added perfume fragrance, was the one which was best suited. 0 After testing for a couple of months, the hospital could confirm that the composition according to the present invention had solved the problem posed in a very satisfactory manner so that the hospital was now no longer bothered by the stench of garbage from its garbage containers or by insect 5 activity around these.

The composition according to the invention is based on an entirely novel concept for combating obnoxious odour emitted from garbage containers, and for reducing insect activity due to a synergistic effect of two of its

ingredients, i.e. an insect repellent substance and a hypo¬ chlorite, whereby the danger of spreading infectious micro¬ organisms via insects is substantially reduced. Basically, it is composed of a granulate having an unusual ability to suck up the moist medium in which bacteria can populate, and a chemical compound, hypochlorite, with disinfecting action against the occurring bacteria. The base substances, i.e. the granulates, can take up/absorb the reactive chemical compounds without being destructed themselves and without baking together. Accordingly, the composition according to the inven¬ tion will also, even in moist condition, have the same proper¬ ties as a dry powder and, accordingly, may easily be poured from one container into another. The addition to the basic composition of the insect repellent substance for effectively combating nuisance caused by insect activity in and around the containers does not alter the free-flowing properties of the composition.

The invention has been illustrated above particularly with reference to the use of sodium hypochlorite solution or calcium hypochlorite granulates as the disinfecting chemical compounds present in the composition according to the inven¬ tion. Accordingly, the difference between these two variants is that when the combination of sodium hypochlorite solution and diatomaceous earth granulates is used the product will appear as a homogeneous product of the absorbing diatomaceous earth granulates with an added amount of sodium hypochlorite solution whereas the product when using the calcium hypochlorite compound instead of the sodium hypochlorite com¬ pound will be a mixed granulate of absorbing base substance and calcium hypochlorite granulate.

In the development of the present invention it was tried to arrive at substances which in very small amounts would show the property of repelling insects, especially flies. Fly larvae do not only develop an extremely unpleasant smell. The flies themselves are efficient spreaders of infec¬ tions from garbage to people in large areas of the world, and, accordingly, it would be of great importance if an efficient chemical or substance for preventing such spreading of infec¬ tions could be found.

After extensive search some substances were found which through interaction with the hypochlorite of the composition according to the present invention exerted what could be considered a synergistic effect with respect to repelling insects from garbage. These substances were camphor oil, citronella oil, pine resins/pine needle oil, naphthalene and citric acid. This list does not claim to be complete and is only illustrative of insect repellent chemicals or substan¬ ces which may be used in the composition according to the in- vention and act efficiently through interaction with the hypochlorite therein.

For testing the efficiency of the mentioned substan¬ ces test series were performed, as follows:

Test boxes consisting of white polyethylene boxes each having a capacity of 5 liters were used. In the boxes several layers of paper towels were placed which had been sprinkled with a bait for attracting insects. For preparing the bait per se large amounts of garbage which had been left lying relatively long was sprinkled with water. The trickle therefrom was collected in a sufficiently large container and well mixed. To the trickle some fish refuse and meat refuse after slaughtering were added in order to produce a "best pos¬ sible" smell. After standing for two days at room temperature fish refuse and meat refuse were strained off. The paper towels were sprinkled with the remaining very stinking mixture.

The test boxes were arranged with a distance of at least 10 meters from each other at a place which gave the best possible equal conditions, i.e. an open place without appreciable slope.

Each of the test boxes was placed upon a pail which had been turned upside down and placed in a cardboard box so that the upper edge of the test boxes flushed with the upper edge of the cardboard box. The latter was of a size rendering good space for evaporation between the walls of the test box and the walls of the cardboard box. The paper towels which had been sprinkled with the stinking bait were in the test boxes.

The chemicals which should be tested as repellants were scattered alone or in admixture on the bottom of the

cardboard boxes. Thus, a container emitting stench from gar¬ bage was simulated.

The effect of the repellent substances was measured by counting the number of "visits" by insects which in fact took place. A "visit by insects" was considered to take place when an insect landed on the paper towels which had been sprinkled with the bait per se. The results of the measurements are presented in the table below. In the table column 1 indicates the substances tested, column 2 indicates the number of grams of the active ingredients used per liter of diatomaceous earth and column 3 indicates the number of visits by insects per hour. The column represents an average of several countings, randomly chosen from casually chosen periods of hours in the course of casually chosen days. in column 1 the letters used have the following meaning:

A = diatomaceous earth ("Absodan" ) only, K = camphor oil C = citronella oil, F = pine resin/pine needle oil, N = naph¬ thalene, S = citric acid, B = standard mixture without repel- lant ( "Absodan"+hypochlorite).

Substances used Grams per liter Insect visits per 1 "Absodan" hour

A 0 > 390

B 17 43

A+F 2 121

A+K 2 172

A+C 2 115

A+S 2 99

A+N 2 120

B+F 2 3

B+K 2 21

B+C 2 17

B+S 2 14

B+N 2 4

It clearly appears from the above table that the ef-

feet of the insect repellent substances tested in combination with the base mixture consisting of the diatomaceous earth product "Absodan" plus hypochlorite gave an insect repellent effect which is significantly greater than what could be ex- pected from the effect of the insect repellent substance and hypochlorite used alone. This particularly pertains to the combination of diatomaceous earth ("Absodan"), hypochlorite and pine resin/pine needle oil (B+F in the table) and naphthalene (B+N in the table) respectively. Accordingly, it has been shown by experiments that a hitherto unknown interaction between hypochlorite and some substances causes a very strong insect repellent effect. Why this combination of substances is so efficient as has been shown is not known. However, it is not very conceivable that the substances react with one another and form novel active repellants when considering that the mixtures seem to be much too stable. It is more probable that the sense organs of the insects react particularly strongly to this combination of chemical substances, to an extent far above the expected total effect based on the effect of each of the substances used alone.

In carrying out the experiments described above much effort was made to eliminate the possible presence of variables which might influence the test results. To eliminate these variables care was taken that a) All test boxes contained the same amount of identical "bait". b) The test boxes were arranged in order to be exposed to as identical surrounding con- ditions as possible, such as temperature, wind, sun irradiation, spreading of stench, etc. c) The positions of all test boxes were inter¬ changed at intervals of about one hour. d) The test boxes were placed so far apart that they would not mutually appreciably influence the results obtained.