Chemistry: molecular biology and microbiology – Apparatus – Bioreactor
Reexamination Certificate
2002-09-19
2004-08-24
Redding, David A. (Department: 1744)
Chemistry: molecular biology and microbiology
Apparatus
Bioreactor
C435S262000, C220S557000, C220S654000, C220S698000
Reexamination Certificate
active
06780637
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates in general to apparatus and method for disposal of putrescent waste material, and in particular the continuous bio-conversion of putrescent waste material.
2. Description of Related Art
Society generates huge quantities of putrescent waste:
farm waste from plants, animals, and birds;
food storage waste;
commercial food preparation waste;
kitchen waste (institutional, restaurant & domestic);
plate waste; and
human waste.
The production of organic compost for municipal refuse or garbage is well known. For example, U.S. Pat. No. 5,082,486 filed on Nov. 16, 1990 by Glogowski teaches a method for the production of organic compost comprising the following steps:
1. shredding the refuse;
2. adding water to saturation;
3. adding earthworms;
4. keeping the water content at more than 80% during at least 30 days; and
5. keeping the mixture at a temperature from 0-54° C. and with a moisture of at least 45% during more than 4 months.
Such a method is not suitable for continuous treatment of large amounts of putrescent waste. Furthermore, the separation of earthworms from the treated waste materials is very difficult.
The prior art suggests various types of bio-conversion facilities for facilitating the production of useful animal products from putrescent waste material. One device and associated method relates to the continuous treatment of large amounts of humid putrescent waste materials by means of fly larvae. Thus, after a relatively short period of a few days, the putrescent waste is converted into a slightly moist odor-free compost. After treatment of the waste materials, the use of fly larvae allows for separation of the larvae from the waste. Live or dehydrated larvae constitute an excellent feed stock for fish and poultry, but the larvae can also be used for the production of by-products such as protein meal, fats, chitin, and chitosan. It has been observed that when using fly larvae for the treatment of putrescent waste materials, it is possible to induce them to crawl out of the waste by exposing the waste to an illumination, preferably together with a heating, especially an infrared illumination, whereby the separation of the larvae out of the putrescent waste is obtained by the larvae themselves.
The Black Soldier Fly
The larvae that we have chosen for this waste disposal process is the larvae of the black soldier fly (
Hermetic illucens
). It is a tropical fly indigenous to the Americas, from the southern tip of Argentina to Boston and Seattle. During World War II, the black solider fly (BSF) spread throughout the world. Today, it can be found in China, Japan, Korea, the Philippines, Vietnam, Laos, Cambodia, Thailand, Indonesia, Singapore and even Australia. Unlike many other flies, BSF adults do not go into houses; they do not have functional mouth parts; they do not eat waste; they do not regurgitate on human food; and therefore, they are not associated in any way with the transmission of disease. BSF adults do not bite, bother or pester humans in any way. Even though BSF larvae have been known to survive inside the human gut if swallowed whole, this is extremely rare and poses absolutely no danger to humans.
BSF adults are around only for the purpose of mating and laying eggs. The adults congregate in small numbers near a secluded bush or tree in order to find and select a mate. After mating, the female searches for a suitable place to lay her eggs. She produces about 900 eggs in her short life of 5 to 8 days. (Housefly adults, by contrast, live up to 30 days.) Half of the population of adult black soldier flies (the males) never go near waste, since males to not lay eggs. Actually, the females prefer not to lay their eggs upon the waste, but either above or to the side of the waste. In this way, the eggs have a far better chance of surviving. The eggs are very slow in hatching (102 to 105 hours). The newly hatched larvae then crawl or fall onto the waste and begin to eat and digest it with amazing speed.
Under ideal conditions, it takes about two weeks for the larvae to reach maturity. If the temperature is not right (above 21° C. or 70° F.), or if there is not enough food, this period of two weeks may extend to four months. This ability of the BSF larva to extend its life cycle under conditions of stress is a very important reason why it was selected for this waste disposal process. BSF larvae pass through five stages or instars. Upon reaching maturity, the larvae are about 25 mm (1 in.) long, 6 mm (0.24 in.) in diameter, and they weight about 0.2 gm (0.0014 oz.). The larvae are extremely tough and robust. They can survive under conditions of extreme oxygen deprivation. It takes them, for example, approximately two hours to die when submerged in rubbing alcohol. They can be subjected to several 1000 g's of centrifugation without harming them in any way. BSF larvae are strong, robust, flexible, adaptable, and very easy to manage.
But their greatest attribute, of course, lies in their ability to eat and digest raw waste. They can devour, for example, a large, raw Irish potato in just a few hours. Many species of flies cannot eat raw waste, unless the waste first undergoes a certain level of bacterial decomposition. Not so with the larvae of the black soldier fly. Since the BSF larvae have very large mouth parts, they can shred and ingest raw waste far more efficiently than any other known species of fly. The only things that they cannot shred are large pieces of food waste of a high cellulosic, calcium or chitin content, such as the shell of a coconut, crab or shrimp, or a piece of bone. Therefore, it would be advisable for us to shred these tough objects to a grain size small enough to be ingested by the BSF larvae. This also assures a relatively uniform grain size with respect to the larvae residue.
BSF larvae have amazing appetites. In a small experiment conducted in Texas over a period of one year, it was determined that the BSF larvae can digest over 15 kg of raw waste per m
2
of disposal per day (approximately 3 lbs./ft
2/
day). As a sidebar, it is also noted that within a single day this 15 kg of waste was reduced to less than 1.5 kg of larval residue. In other words, an optimal bio-conversion processes utilizing the BSF may expect a 90% reduction in the weight and volume of the food waste within a 24-hour period. On the surface of the disposal unit, one finds a thick layer of actively feeding larvae in all stages of growth. The moment the food waste is deposited into the unit, it is digested by the BSF larvae long before it has had a chance to degrade complex organic compounds. Therefore, most of the nutrients and energy within the waste are conserved and recycled with the help of the BSF.
While actively feeding, the larvae secrete a chemical, more precisely an infochemical, that permits them to communicate with other species of flies. This infochemical or synomone allows them to tell other flies to stay away, that it makes little sense to lay their eggs within an area full of actively feeding BSF larvae. This interspecies communication is indeed very effective. In the vicinity of the disposal unit, we note the near absence of houseflies and all other flies that are a pest to humans. If only we could isolate this natural fly repellant produced by the BSF larvae! After about two weeks of feeding, the BSF larvae reach maturity. They turn from white to black, their mouth parts transform into a digger, they empty their guts of waste, they secrete an antibiotic to protect themselves from bacteria, and they set out in search of an ideal pupation site.
An Ideal Pupation Site
The BSF larvae will easily crawl over 100 meters (320 ft. +) in search of an ideal pupation site. An ideal pupation site must be free of the enormous bacteriological activity which characterizes the waste disposal area, free of small predators such as predatory mites and pseudo-scorpions, and free as well of large predators such as birds, rats and mice. Furthermore, an ideal pupation site is never simp
Buchel, Jr. Rudolph J.
Redding David A.
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