Patent Application
20130196423
The current application is directed to composting of organic waste and, in particular, to a system and method for processing organic waste in optimal or near-optimal fashion in order to control odor, minimize unprocessed waste emissions, and maximize bacterial processing of the organic waste.
Processing of organic waste, including discarded food and food-related materials and ground yard waste, is a commonly employed organic-waste-processing method that uses controlled bacterial digestion of organic waste to remove pathogens and break down organic waste into humus that is usable as a soil conditioner and fertilizer for gardening, landscaping, and agriculture. Many types of composting vessels and system have been developed, including rotating drums with porous surfaces, static or aerated piles with perforated floors, agitator-based systems with perforated floors, and other systems. However, in general, none of the currently available systems provide optimal control over emission of odors and wastes and optimal employment of aerobic bacterial digestion of the organic wastes. Gardeners, waste processors, farmers, and others who employ composting of organic waste and/or consume the end products of composting continue to seek effective new systems and methods for processing organic waste via composting and composting-related processes.
The current application is directed to systems and methods for processing organic waste using aerobic bacterial digestion of organic waste. In one implementation, the system includes a covered enclosure with a non-porous floor and sidewalls within which a floor-scraping, helical auger with serrated or toothed edges is mechanically powered and translated in two dimensions in order to chop, mix, lift, and move composting organic waste towards a discharge end of the enclosure. The vessel additionally includes a rotatably mounted screen, in one implementation, for screening the composted organic waste as it is discharged. The vessel additionally includes, in one implementation, perforated, pressurized tubes for introducing pressurized air into the organic waste as it is processed as well as a flexible water hose for introducing moisture into the organic waste as it is being processed. Various sensors are employed to monitor and control the moisture, temperature, and other physical parameters of the organic waste by controlling rotation and translation of the helical, floor-scraping auger and, in certain implementations, controlling the pressure of pressurized air input into the perforated, pressurized tubes and the rate of water flow to the flexible water hose.
The process of aerobically composting organic waste occurs in several stages and involves control of the biological environment to enhance degradation. Control parameters include moisture content, oxygen levels, particle size, and availability of degradable substances and nutrients. The process is dynamic and requires adjustment to rebalance parameters during the 20-60 day processing time. Moisture levels typically start at 55-65 percent and reduce to 35-45 percent by weight by the end of the process. The reduction in moisture is a result of biological heat generated during the compost process and the subsequent evaporation of moisture. The more degradation that occurs, the more moisture is lost. The composting waste may have to be rewetted several times during the process to maintain moisture levels required for bacterial growth. Particle size typically reduces during the process to allow bacteria fresh surface area for continued growth.
Organic waste materials such as food waste, sludge, and manures are typically contaminated with undesirable debris, such as plastic trash, medical waste, or other non-degradable substances. The process of composting organic waste materials into a reusable soil amendment typically involves screening to remove these objects at the end of the compost process before the compost is applied to land or sold at market. The compost is dried to 45 percent moisture or less for screening to occur. The fractionation of compost particles typically occurs by agitating the compost as it moves across a wire mesh or perforated plate deck.
During operation, the organic waste is loaded into the load end the vessel by conveyor, bucket loader, or other means. The translatable assembly moves the auger to the load end of the vessel, stirring and shredding the organic waste as it biodegrades during the compost process. Additionally, the translatable assembly may move the auger side-to-side in the vessel. The pattern of motion of the auger determines the rate at which the organic waste is moved from the load end to the discharge end of the vessel. The control program can control auger movement according to a multitude of patterns to move organic waste at various speeds from the load end to the discharge end of the vessel and in the reverse direction. During the process of moving processed organic waste from one end to the other, the organic waste undergoes biological degradation, which generates heat and removes water by evaporation. Moisture is added back to the organic waste via the water hose mounted to the translation assembly. Removal of water from the compost reduces clumping and improves the screening process. The drying process can be further enhanced by enclosing the vessel with a light permeable membrane, allowing solar heat to warm the organic waste and accelerate the drying process. The drying process is accelerated by the addition of pressurized air at the base of the composting vessel to maintain optimum biological activity and heat generation. The pressurized air can be heated to further enhance the drying of the compost.
Once the organic waste reaches the discharge end of the vessel, the auger lifts the dried and composted material onto a screen, through which it drops onto a perforated deck 506 with holes sized to allow the fine organic material to drop through the holes into receiving bin 502 when the deck is vibrated. The larger particles are retained on the upper surface of the perforated deck and are discharged off the end of the deck into receiving bin 504 or allowed to accumulate on the ground. This sufficiently dries and sterilizes the larger particles for reuse as animal bedding while producing a fine compost product.
Although the present invention has been described in terms of particular embodiments, it is not intended that the invention be limited to these embodiments. Modifications within the spirit of the invention will be apparent to those skilled in the art. For example, the organic-waste-processing system may employ any of many different types of processor-coupled sensors in order to inform the control program of the current status of any of many different types of sensed physical parameters, from oxygen level, water moisture, and temperature to the presence of various types of bacterial-degradation chemical products. Additional mechanical controls may be employed to open and close apertures within the enclosure and to alter the amount of sunlight entering the enclosure in order to control temperature. Various additional mechanical features may be included in order to facilitate controlled discharge of processed organic waste from the enclosure. The dimensions, pitch, and number of teeth per linear dimension along the outer edge of the helical auger may all be varied in order to provide optimal mixing, shredding, and processed-organic-waste movement within the enclosure. In the illustrated embodiment, the processed organic waste is separated into fine particulate humus and larger particles, such as shavings, wood chips, and other fibrous materials that may be re-used for animal bedding. In alternative implementations, additional types of separation may be employed to partition the processed organic waste into a greater number of components. Additional mechanisms may facilitate removal of unwanted debris from the top of the screen, such as non-biodegradable plastics, metal objects, and other such debris.
It is appreciated that the previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present disclosure. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the disclosure. Thus, the present disclosure is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
This application claims the benefit of Provisional Application No. 61586003, filed Jan. 12, 2012.
| Number | Date | Country | |
|---|---|---|---|
| 61586003 | Jan 2012 | US |
