METHOD AND DEVICES FOR BIOLOGICAL PURIFICATION OF WASTE

Abstract: Process and apparatus for biological purification of organic wastes with earthworm compost including composting of solid materials on top of a water permeable layer and inoculation of an earthworm population in the compost material, comprising a sloping surface for removal of leakage water, spaced underneath the layer. In one embodiment of the apparatus according to the invention, the compost material is accommodated in an inner enclosure (7), surrounded and spaced from an outer enclosure (11) through which water from bath, laundery and dishes (BDL-water) is lead for heating of the compost material by engaging the bottom of the inner enclosure, and for humidification of the compost through drawing, by means of capillary action (17), BDL-water from a space (13) between the enclosures and into the inner enclosure.

Description: Method and devices for biological purification of waste. The present invention relates to a process and apparatus for biological treatment of organic wastes with earthworm compost and at a larger scale a process for purification, stabilization, dewatering, desalinization, composting and degradation of household wastes and sewage sludge with continuous and rapid removal of leakage water. Dewatering of liquid sludges at purification plants is an expensive process which in general is achieved through centrifu- gation. This does not only demand high initial costs of invest¬ ment but also a great deal of energy supply. To perform dewater¬ ing it is nesessary to stabilize the sludge through anaerobically degradation or by adding chemicals. Many small purification plants lack facilities to dewater the sludge which means that the sludge has to be transported by trucks to larger units equipped with centrifuges. The residues are unpleasent regarding texture and odours. Costs arise both from transportation of water and the disposal of the dewatered sludge. The dewatered sludge moreover has a tendency to get mouldy which constitutes a health risk for the staff at the plant. A number of such processes are anaerobic, permitting pathogenic organisms to multiply. To prevent and counter act the disadvantages of conventional techniques, a large scale aspect of the invention provides a process and related apparatus for stabilization, dewatering of liquid sludges containing down to a few percentage solid matter, desalinization, composting and degradation. The treated residues receive a price on the market in the form of a compost, with a texture and smell typical for an ordinary soil. The mould problem is eliminated. The process can be arranged for at low costs of investments and low running expenses. The process is aerobic which ensures that harmful microorganisms will be dismissed. In a small scale aspect of the invention there is provided a process and related apparatus for biological waste purification with dewatering and composting of organic wastes from one or more households not being connected to municipal wastewater plants. Abovesaid purpose of the invention is met in a process and apparatus as set forth in the attached claims. The invention is described in detail below, referring to the drawings attached, of which Fig. 1 is a cross sectional view showing a vermicompost bed used in the process, Fig. 2 shows the vermicompost bed in Fig. 1 in a small scale application of the invention Fig. 3 shows an outer enclosure to the vermicompost bed shown in fig. 2, Fig. 4 is a cross sectional view of a rootzone, adapted to the process of the invention, and Fig. 5 shows the principles of the invention applied in a small scale aspect. A vermicompost bed 1 with inoculated earthworms, is positioned at a distance above a bottom 2, which is designed to receive and supply continuous removal of the leakage water or water from liquid sludges 3. The bottom 2 can as shown in fig. 1 be supplied with channels or be corrugated and sloping with respect to the horizontal level, and can be supplied with a channel to collect the water at the lower side. The lower parts of the corrugation have a cross sectional area sufficient to lead the water away before it raises to a level high enough to allow the water to be resucked into the compost bed 1. The channels or corrugation comprises side walls, substantially vertical or somewhat sloping to the vertical plane to ensure a quick and mainly vertical removal and outlet of the leakage water so the risk of overflow¬ ing will be eliminated. The water purified from solid particles will be lead away for further removal of dissolved plant nutrients. Spaced above the bottom 2 is arranged a water permeable barrier layer 4, resting in a frame, not further presented here, of suitable design. Said barrier layer includes e.g. mineral wool which lets the water through but not the earthworms being inoculated into the compost bed. On top of the barrier layer 4 is arranged a protective net 5 to protect the barrier layer from mechanical damage for example when the compost is ready for use and is removed. Reference numeral 6 refers to distributor pipes for water and unpurified wastes or liquid sludges, and may as illustrated in the drawing, be a number of pipes evenly distrib¬ uted above the surface of the compost bed or a single, periodi¬ cally or continuously moving distribution pipe. The vermicompost bed can also be designed as a basin in level with the ground, or be built enclosed in a box or placed on a table in one or several levels and thus adapted to the space available. Fig. 2 shows a vermicompost bed of abovesaid design for use in a small scale aspect, and wherein identical components are designated by identical reference numerals. The vermicompost bed 1 in Fig. 2 includes a bottom 2, spaced underneath a barrier layer 4 and a protective net 5 of a frame, as indicated in the drawing, which prevents leakage water to escape between the barrier layer and the walls of a box, described below, inside which the vermicompost is positioned. The bottom 2 has channels or is corrugated, as suggested in a diagonal direction and is designed with a surrounding channel to lead drainage water away to an external collection vessel 30. The channels or corrugation comprises side walls that extend substantially vertically or somewhat sloping with respect to the vertical plane, to ensure a quick and mainly vertical removal and outlet of leakage water and urine. The outlet 31, which passes through the outer enclosure and leads to a vessel 30 as described below, is positioned low enough to secure a substantial and operative drainage of the corrugation and the bottom 2. In this application the vermicompost bed is positioned inside an inner enclosure or box 7 to receive latrine, i. e. urine, water and solid organic wastes. In the box, decomposable kitchen wastes and sludges from filters or from sludge separating vessels can be put. It is preferable that the box 7 is divided into two or more separate chambers, and is therefore sectioned by partition walls 8. These walls may be displaceable in the box 7 to make degrada¬ tion capacity adaptable to varying loads, e.g. when used during different seasons of year and to allow for a completed decompost- ing process in a section not currently used before the compost material is taken out. In a lower area, the walls are perforated with a number of holes, not shown, through which the worms can migrate from a section wherein the composting process is completed to another section containing fresh material. The holes are suggested to have a diameter of about 6 mm and can be distributed over the lower third of the area of the partition wall. At a distance above the bottom 2, openings 9 are provided in the side walls of the box 7. Said openings are formed as slots or grooves and are protected from falling waste material or compost by roofs 10, attached to the inside of the side walls. The slots 9 can be provided in respective side wall of the box 7 and in a number suitable for the number of sections inside the box. Furthermore, the top edges of the walls of the box 7 may include inwardly bent flanges or rims to prevent earthworms to crawl over the edges. In Fig. 3, the inner box 7 with the vermicompost bed 1 is schematically shown in dotted lines. An outer enclosure or box 11 surrounds the box 7, the later resting on inserts 12 so that a space is formed between the bottoms of the two boxes. Inserts 12 are also placed between the side walls of the boxes 7 and 11 and forming a space 14. To the space 13, BDL-water (from bath, dishes, laundery) is led, or fresh water is filled through an inlet opening 15. An outlet opening 16 leads the water away, e.g. to be filtered into the ground or preferably absorbed in a root bed. Inlet and outlet openings 15, 16 are placed at such heights that the water is retained at a level ensuring a permanent contact between the corrugated bottom of the box 7 and the BDL-water surface. By utilizing and transferring the heat of the BDL-water to the vermicompost bed, a high level of activity and metabolism is maintained with the inoculated earthworms. The corrugation of the inner box 7 is then increasing the contact area with the water for more efficient use of heat remaining in the BDL-water. A strip 17, made from an absorbant material such as unwoven clothing, is descending into the space 13. The strips 17 rise into the space 14 and through each slot 9 of the side walls, into the inner box and partly onto the surface of the protective net 5, and is thus partly covered with the bedding material and compost. Through capillary forces BDL-water is drawn, by the strips 17, from the space 12 to the compost material for humidification. The purposes are two; firstly the compost is prevented from drying during periods when fresh material is not supplied, and secondly it prevents harmful saline concentrations from building up and poisonous degradation products to be enriched due to the continuous supply of urine. The supply of BDL-water thus improves the life conditions of the earthworms and ensures the function of the biological waste water purification construction. The BDL-water in the space 13 is thus used both for heating and remoisturing the compost. It is realized, without this being actually shown, that pipes and pumps, and if necessary sludge separators and filters can be arranged to serve the compost bed, wherein the distribution pipes are movable to distribute latrine to different sections of the box 7. After the surplus heat has been used the BDL-water, without being mixed with drainage water leaking from the compost bed, is being further led through the outlet opening 17 to a root bed, see Fig. 4 to ensure uptake of plant nutrients, especially phosphates. In the root bed, at a frostfree depth, perforated drainage pipes 18 are arranged in curves in at least two intersecting planes in the longitudinal extension of the pipes, e.g. in a horizontal and a vertical plane, resp., and thus forming a helix. This arrangement of the pipes forces the water to pass both in and out of the pipes and thus balance moisture and concentrations of plant nutrients, improves the absorption due to prolonged time of flow through the ground and optimizes the distribution of nutrients in the rootzone. The rootzone can be sowed with a strongly growing grass, being planted with bushes, garden vegetables, fodder plants etc. From the rootzone the water can be led to a recipient eventually after passing a basin for airing. It can finally be used for watering or let out into a receiving body of water. Fig. 5 shows schematically a small scale application of the invention. Latrine is led from toilets 20, preferably with a sparsely water flow, eventually through a pump 21 to the vermicompost bed in the house 22, surrounding the compost. To serve a number of households several compost houses can be interconnected or be constructed as a larger unit divided into separate chambers with distribution tubes to each chamber. To the compost house 22 is also led BDL-water 23 through a sludge separation vessel 24. Drainage water leaking from the compost in the house 22 is collected in the vessel 25. The BDL-water is led or pumped from under the house 22 to the rootzone 26 after its remaining heat has been used in the vermicompost bed. From the rootzone, in which the BDL-water repeatedly has flown in and out of the windings of the drainage pipes, it is led purified to a recipient eventually after being aired in a pond 27. The compost house 22 can as shown be designed as a building above ground or being placed more or less below the ground surface. Through empirical studies it has been found that earthworms of the species Dendrobaena veneta advantageously is inoculated in the compost bed, as well as worms of the species Eisenia foetida. Perionvx excavatus and Eudrilus euσeniae. Finally, the compost bed is advantageously initiated by a capillarity breaking material layer which is spread onto the protective net and thus providing a shed and favourable conditions to the worms already from the start of the process.

Claims: CLAIMS 1. Process for biological purification, stabilization, dewateri¬ ng, desalinization and degradation of household wastes, latrine and liquid sludges, including composting of solids and inocula¬ tion of an earthworm population forming a vermicompost positioned on top of a water permeable layer (4), characterized by - providing a bottom (2), spaced underneath the layer (4), continuously collecting leakage water on the bottom to counteract acidification, lack of oxygen and increased saline concentration, continuously leading said leakage water away from the compost for further treatment, supplying water from bath, laundery and dishes (BDL-water) to the compost bed (1) to heat the compost bed from underneath, and supplying, by capillary action, BDL-water to the compost bed for desalinization and for preserving the humidity. 2. Process according to claim 1, characterized by removing the BDL-water from a height to ensure that the bottom (2) continuously is in contact with said BDL-water. 3. Process according to claims 1 and 2, characterized by leading (31) the leakage water from the compost bed to a collection vessel (30) and leading the BDL-water to an infiltra¬ tion/absorption plant, preferably to a rootzone, and subsequently leading the BDL-water to a receiving body of water for absorption of oxygen. 4. Process according to the preceding claims, characterized by the vermi compost being inoculated with worms from the species Dendrobaena veneta. Eisenia foetida, Perionvx excavatus or Eudrilus euαeniae. 5. Apparatus for biological purification and degradation of household wastes, latrine and liquid sludges, including compost¬ ing of solids and inoculation of an earthworm population forming a vermicompost bed (1) having a water permeable barrier layer (4), characterized by - an inner enclosure (7) accommodating the vermicompost bed, and an outer enclosure (11) spaced (13,14) around a bottom (2) and side walls of the inner enclosure, said bottom (2), spaced underneath the barrier layer (4), comprising an outlet (31) for removal of leakage water from the bottom (2), said outlet running from the inner enclosure (7) and penetrating the outer enclosure (11), - inlet (15) and outlet (16) openings, resp., for transportation of BDL-water being provided in the outer enclosure, and - openings (9) provided in the side walls of the inner enclosure (7) through which BDL-water is supplied from the outer enclosure (11) to the vermicompost bed. 6. Apparatus according to claim 5, characerized by said bottom (2) comprising channels or corrugations having side walls of substantially vertical orientation for drainage and removal of leakage water, and by said BDL-water transportation openings (15,16) being arranged at a height that ensures the bottom (2) of the inner enclosure continuously to be in contact with the BDL- water remaining inside the outer enclosure. 7. Apparatus according to claims 5 and 6, characterized by said openings (9) accommodating stripes (17) with capacity to draw, through capillary action, BDL- water from the space between the outer and inner enclosures and into the vermicompost bed. 8. Apparatus according to claims 5, 6 and 7, characterized by at least one partition wall (8) displaceable inside the inner enclosure, the wall comprising through holes of a diameter of about 6 mm in the lower third of its surface area. 9. Apparatus according to claims 5, 6, 7 and 8, characterized by the BDL-water outlet opening (16) being connected to a rootzone, said rootzone accommodating curved drainage pipes (18), the curves being applied in at least two intersecting planes in the longitudinal extension of the pipes. 10. Utilization of water from bath, laundery and dishes for heating a vermicompost bed in accordance with any of the preceding claims. 11. Utilization of water from bath, laundery and dishes for moistening a vermicompost bed in accordance with any of the preceding claims.

Inventors: LOFS ASTRID, MIDELF GOETE, LOFS, ASTRID, MIDELF, GOETE
Applicants: BIOGLOBE AB, LOFS ASTRID, MIDELF GOETE, LOFS, ASTRID, MIDELF, GOETE
Application year: 1996
Main classification: C05F17
IPC codes: C05F17