1	The Bio-Conversion of Putrescent Wastes ESR LLC 519 West Dejean Street PO Box 250 Washington, Louisiana 70589 Tel. 1-337-826-5540 prepared by Dr. Paul A. Olivier
2	Imagine Suppose we were asked to imagine the best possible way to dispose of putrescent waste, to imagine a totally natural process that would effect an enormous reduction in weight and volume within a matter of just a few hours. This process should require no energy, no electricity, no chemicals, not even water. It should be totally self-contained and not emit a drop of effluent, and aside from a small
3	Simple & Easy to Operate amount of carbon dioxide, it should not produce methane or any other greenhouse gases. The unit housing this process should operate with the simplicity of a garbage bin. It should have no moving parts, and it should require very little servicing and maintenance, very little expertise or experience to operate. It should not emit offensive odors, and it should drive away houseflies and
4	Unlimited Quantities other filth-bearing flies. The process should not only generate its own heat, but it should also regulate heat to assure maximal bioconversion throughout the winter months. This simple and inexpensive unit could be situated out-of-doors in a shaded area, and any number of units could be coupled together to handle unlimited quantities of waste.
5	On-site Recycling of Food Waste Since food waste would be rapidly reduced and recycled at its point of origin, it would eliminate altogether the collection, transport and land-filling of food waste. This bioconversion process, however, should not demand the introduction of anything foreign or exotic.
6	No Transmission of Disease It should be powered by a creature commonly found throughout the world, and even though this creature may have lived alongside humans for thousands of years, it should not be associated in any way with the transmission of disease. In view of the wide variability of putrescent waste presented to it, this benign creature should possess one of the most robust digestive systems within nature.
7	Ideal Bioconversion Agent It must have the ability to thrive in the presence of salts, alcohols, ammonia and a variety of food toxins. In addition to food waste, it should also be able to process swine, human and poultry waste. Upon reaching maturity, it should be rigidly regimented by evolution to migrate out of the unit and into a collection bucket without any human or mechanical intervention.
8	Reintegration of Nutrients This self-harvesting grub should represent a bundle of nutrients that should rival in commercial value the finest fish meal. Why not boldly insist upon the reintegration into the feed chain of most of the nutrients contained within putrescent waste?
9	Ideal to Real Is the bioconversion process described above nothing but a fanciful leap of the imagination? Hopefully as we proceed, it will become clear that this process does, indeed, exist, and that it represents the cleanest, most efficient, and most economical way to recycle most types of putrescent waste.
10	The Black Soldier Fly The agent chosen for this bioconversion process is the larva of the black soldier fly (SF) Hermetia illucens, a tropical fly indigenous to the whole of the Americas, from the southern tip of Argentina to Boston and Seattle. During World War II, the black soldier fly spread into Europe, India, Asia and even Australia.
11	The Adult Black Soldier Fly
12	Flies & Bacteria Many of us panic when we see the word “fly,” just as we often panic when we see the word “bacteria.” Yes, there are noxious, filth-carrying flies that transmit deadly, disease-bearing bacteria. But not all bacteria and not all flies are harmful to humans. Without bacteria and flies, life as we know it on earth could not exist. Both play an essential role in the recycling of nutrients within the food chain.
13	Intense SF Competition Just as benign bacteria compete with harmful bacteria and block their proliferation, so too, the soldier fly aggressively competes with filth- bearing flies and very effectively blocks their proliferation. Just as certain Calliphorides are used to clean out necrotic human tissue, SF larvae can be used to dispose of the large quantities of putrescent waste generated through human activity.
14	A Beneficial Fly Unlike many other flies, SF 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. Adults do not bite, bother or pester humans in any way. Even though their larvae have been known to survive inside the human gut if swallowed whole,
15	Enteric Myiasis this only happens under utterly extreme and bizarre conditions and poses no real danger to humans. True enteric myiasis does not exist in man through the agency of SF larvae or any other fly larvae, whereas pseudomyiasis can occur, even through the agency of ordinary houseflies. SF adults congregate near a secluded bush or tree in order to find and select a mate. After mating, the females search for a suitable place to lay their eggs.
16	Life Cycle A female produces about 900 eggs in her short life of 5 to 8 days. Housefly adults, by contrast, live up to 30 days, and during this long period, they must eat, and in so doing, they are actively engaged in the spread of disease. SF eggs are relatively slow in hatching: from 102 to 105 hours. The newly hatched larvae then crawl or fall onto the waste and eat it with amazing speed.
17	Life Cycle Under ideal conditions, it takes about two weeks for the larvae to reach maturity. If the temperature is not right, or if there is not enough food, this period of two weeks may extend to six months. The ability of the SF larva to extend its life cycle under conditions of stress is a very important reason why it was selected for this putrescent waste disposal process. SF larvae pass through five stages or instars. Upon
18	Tough & Robust reaching maturity, they are about 25mm in length, 6mm in diameter, and they weigh about 0.2 grams. These larvae are extremely tough and robust. They can survive under conditions of extreme oxygen deprivation. It takes, for example, approximately two hours for them to die when submerged in rubbing alcohol. They can be subjected to several 1000 g’s of centrifugation without harming them in any way.
19	Texas Experiment In an experiment conducted in Texas over a period of one year, ESR LLC determined that SF larvae can digest over 15 kilograms per day of restaurant food waste per square meter of feeding surface area, or roughly 3 lbs per square foot per day. A 95% reduction in the weight and volume of this waste was also noted. This means that for every 100 lbs of restaurant food waste deposited into a unit, only 5 lbs of a black, friable residue remain!
20	Nothing More Powerful
21	Huge Mass of Larvae
22	Two- to Four-Inch Layer Over 100,000 active larvae can be found in a typical waste disposal unit, and in contrast to red worms, these larvae have the ability to eat and digest just about any type of putrescent waste, including meat and dairy products. On the surface of the disposal unit, we typically see a 2- to 4-inch layer of actively feeding larvae in all stages of growth. The moment waste is deposited into the unit, the larvae begin
23	Powerful Enzymes to secrete powerful digestive enzymes into the waste long before it begins to rot and smell. Since thermophilic and anaerobic bacteria play no part in this process, these tiny creatures are able to conserve and recycle most of the nutrients and energy within the waste. While actively feeding, the larvae secrete an info-chemical that permits them to communicate with other species of flies.
24	Synomone This synomone allows them to tell other flies that it makes little sense to lay their eggs within an area full of actively feeding SF larvae. This interspecies communication is 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.
25	An Ideal Pupation Site Upon reaching maturity, SF larvae change color from beige to black, their mouth parts transform into a digger, they empty their guts of waste, and they set out in search of an ideal pupation site. SF larvae will crawl over 100 feet in search of an ideal pupation site. An ideal pupation site consists of a dark, dry area providing refuge or cover for the
26	Exiting the Disposal Unit mature prepupal larvae. SF larvae are negatively phototactic (afraid of light), and therefore most of their migratory activity takes place at night. Their migration initially appears to be a random search for a way out of the waste. If a ramp of an upward inclination lies at the edge of the waste, they will make every effort to negotiate this ramp. If this ramp has an angle less than 40 degrees, the larvae will
27	Steep Angle have no problem exiting the unit. Such a steep angle makes it difficult for the larvae to carry along any adhering residue, and it also serves as a barrier for the larvae of most other species of fly. Housefly larvae generally are not able to negotiate a dry ramp of a 20-degree angle, and if they cannot get out of the disposal area, they cannot pupate, and if they cannot pupate, they cannot become adults and
28	A Fly Trap Set by a Fly reproduce. The SF waste disposal unit mounted with steep ramps serves as a very effective sink or trap for the larvae of just about every species of fly that ignores the chemical warning to stay away from the unit. Once trapped within the unit, these uninvited larvae and pupae constitute one more item of food for the hungry SF larvae.
29	Self-Harvesting At the summit of the ramp, an exit hole is provided, and this hole discharges into a collection bucket. SF larvae are totally self-harvesting. They abandon the waste only when they have reached their final mature prepupal stage, and they crawl out of the waste and into a bucket without any mechanical or human intervention.
30	Plastic and Concrete ESR LLC will soon begin the manufacture of soldier fly bioconversion in both plastic and pre-cast concrete. These units resemble garbage bins, but these bins (US patent 6,780,637) are somewhat special in that they possess evacuation ramps that permit the larvae to self-harvest into a bucket. Ramps begin at the bottom of the unit and spiral up to the top. The next slide shows the path that the larvae take in exiting the unit:
31	Interior Top View
32	Side View
33	Small Spiral Ramps The spiral ramps need not be wider than about one inch. Consequently they occupy little space and incur little loss in the holding capacity of the unit. The ramps are created by means of a fold in the wall of the container. In this way, there is no underside of the ramp within the container where migrating larvae might uselessly congregate.
34	Right & Left Ramps The round shape of the unit greatly assists the mature larvae in exiting the unit. As they randomly orient toward the periphery of the waste, they encounter the rounded wall of the container, at which they may turn either right or left. If they turn right, they eventually come to the base of the right ramp, and if they turn left, they eventually come to the base of the left ramp.
35	High Crawl-off Efficiency Since the total distance that the larvae must travel in exiting a unit is very small, the efficiency of larval crawl-off is fully optimized. Let us look at some of the main features of the 2-ft unit:
36	Small Swivel Lid for Waste Input
37	Large Lid for Servicing
38	Underside of Lid
39	Indented Handle
40	Ramp: a Fold in the Wall
41	Collection Bucket
42	Bulkhead Hose Fitting
43	Flexible Hose
44	Hose Clamp
45	Lip to Prevent Unwanted Crawl-off
46	Underside Showing Vent & Access Holes
47	Capacity This 2-foot unit has an average feeding surface area of 0.34 M². At a disposal efficiency of 15 kgs/ m²/day, it can handle over 5 kgs of food waste per day. It can hold or contain over 144 liters of larval residue, and with a reduction in weight and volume of 95%, it must be emptied after receiving a total of 2.89 m³ of food waste.
48	Frequency of Clean-Out This unit serving a family of four people would have to be cleaned out once every 8 years. With this larval bioconversion process, the costly transport of food waste to landfill is completely eliminated.
49	Pre-cast Concrete The most inexpensive way to manufacture soldier fly bioconversion units is by means of pre-cast concrete. But a pre-cast unit molded as a single part will be difficult to handle and transport. However, if molded in three vertical sections of 120 degrees, these sections are easy to handle, and they can be stacked against one another to reduce transport volume. Another advantage of molding the unit in three sections: no
50	Barrel Technology metal reinforcement of the concrete is required. Since the three sections are held together by three nylon straps in much the same way that an oak barrel is held together by bands of steel, stress on the unit is relieved at the points of intersection of the three sections. All that is needed for the fabrication of the unit is a dollar or two of cement, and recycled materials such as stone, brick or
51	Hypertufa Bioconversion Units broken glass can serve as aggregate or filler. To reduce the weight of pre-cast concrete, a lightweight aggregate such as perlite and vermiculite can be used. If this results in a reduction in strength, a small quantity of polyvinyl alcohol fibers (0.5 % by volume) can be added. The construction of bioconversion units could take on many of aesthetic qualities of
52	Assembly of 2-Foot Unit Hypertufa: lightweight, artificial stone containers. See http://www.backyardgardener.com/tufa.html The following slides show how the parts of a 2-foot bioconversion unit are assembled:
53	Main Section
54	Left Section
55	Right Section
56	Nylon Strap
57	Nylon Strap
58	Nylon Strap
59	Balcony
60	Balcony
61	Balcony
62	Metal Strip
63	Metal Strip
64	Metal Strip
65	Fasteners
66	No Bottom Note that the unit has no bottom. The unit can be situated above a bed of sand that would serve as a partial filter, and any nutrients that escape this filter could be absorbed by the roots of plants situated around the perimeter of the unit. In this way any free liquids liberated by the larvae in the digestion of the waste do not necessitate the introduction of bulking materials. This greatly simplifies the operation of the unit.
67	A Simple Lid If left out in the open, the unit must have a lid to prevent rainwater from coming in. A lid could consist of nothing but a sheet of plastic or plywood. The fasteners that hold down the metal strips at the top of the unit create sufficient space in between the unit and the lid to allow soldier fly access into the unit.
68	Exit Pipe
69	Exit Pipe
70	Bio66
71	Ideal for Developing Countries Such a unit is ideal for use in developing countries where the cost of materials are high relative to the cost of labor. Since cement is abundant and readily available throughout most developing countries, since very little skill is needed to fill a mold, small workshops could be easily set up to serve a specific area or province, thereby eliminating the costly transport of units over
72	Less Than $10 long distances. Our goal is to sell a unit capable of disposing of all the putrescent waste from a single household for less than $10 US dollars. Larger units could be easily constructed in the same simple manner as indicated above by changing the angle from 120 to 60 degrees, and by increasing the number of ramps from two to four. In this case, a unit would consist of six
73	Larger Units vertical sections. Since one half of a unit would identical to its other half, the entire unit could be fabricated, once again, out of three molds. The following slides show how the parts of 6-foot unit are assembled:
74	6-Foot Unit
75	6-Foot Unit
76	6-Foot Unit
77	6-Foot Unit
78	6-Foot Unit
79	6-Foot Unit
80	Urine-Diverting Toilet Pre-cast concrete could easily support the weight of a pre-cast concrete lid that could incorporate all of the essential features of a urine-diverting toilet. The following drawing depicts a 2-foot diameter unit with a urine-diverting toilet molded into the lid.
81	Urine-Diverting Toilet
82	The Fish Pond Latrine The practice of raising fish on raw human excreta has existed for hundreds of years in certain parts of Asia. The Pangasius catfish, for example, grows rapidly on raw excreta, yet the economic benefit derived from raising this fish is offset by roughly 30 excreta-related diseases associated with this practice, including dysentery, typhoid fever and cholera. In spite of the health risks associated with
83	The Soldier Fly Latrine this practice, farmers are reluctant to forego the income derived from the sale of latrine fish. But if soldier fly larvae could be used to culture a broad range of aquatic life of a significant economic value, farmers might be persuaded to abandon the fish pond latrine. The environment would greatly benefit as all human, animal and poultry waste could report to the one bioconversion unit.
84	Bioconversion What percentage of fresh food waste bio-converts into fresh prepupae? Over a period of one year, ESR LLC noted that roughly 20% by weight of the fresh food waste converted into fresh larvae. This food waste had an average dry matter content of 37%, and the prepupae had an average dry matter content of 44%. On a dry matter basis, the bioconversion of food waste situates at almost 24%.
85	100 kg Food Waste per Day The following flow diagram is based upon an input of 100 kg of food waste per day. Less than three 6- foot bioconversion units can handle this input.
86	Flow Diagram
87	Analysis of Dried Soldier Fly Prepupae 42.1% crude protein 34.8% ether extract (lipids) 7.0% crude fiber 7.9% moisture 1.4% nitrogen free extract (NFE) 14.6% ash 5.0% calcium 1.5% phosphorus
88	SF Fed to Catfish Studies were conducted at the Coastal Plain Experiment Station in Tifton, Georgia, to examine the suitability of SF prepupae as a feed source for channel catfish and tilapia. The tests concluded that soldier fly larvae should be considered a promising source of animal protein in fish production. Taste tests were also conducted, and the results of these tests indicated that fish fed SF larvae are acceptable
89	Menhaden Fish Meal to the consumer. About half of SF fresh weight translates into a dry meal or pellet, and two nutrition studies done under the supervision of Dr. Craig Sheppard suggest that this dry matter has roughly the same value as Menhaden fish meal valued at over $500 US dollars per ton. Live SF prepupae have been successfully fed to bull frogs, tropical fish, reptiles, snakes and many other creatures that have a
90	Living Food strong preference for living food. Here the value of fresh SF larvae ranges from $4 to $20 /lbs, or $8,000 to $40,000 per ton. If a unit is installed at a residence where the weekly or bi-monthly collection of larvae might be somewhat expensive, the larvae can be placed outdoors in a shallow plastic pan where birds will readily feast upon them. Chickens are especially fond of live SF larvae.
91	As Temperatures Drop SF larvae have an amazing ability to dispose of putrescent waste. But as the temperature drops below 21˚C, their ability to digest waste progressively grinds to a halt, and if they should freeze, they die. This tropical fly larva needs to be sustained at temperatures above 30˚C if it is to continue to digest putrescent waste at the standard rate of roughly 15 kgs/m² of unit surface per day.
92	A Winter Strategy To bring bioconversion units indoors during winter would be costly, and to equip them with heating coils is not necessary. The strategy proposed here involves nothing more than placing a styrofoam sheet on top of the larval residue to retain the heat generated by larval movement. If this heat is not allowed to escape, the temperature on the surface of the residue easily exceeds 35˚C.
93	Graphs The following graphs plots daily temperature readings both outside the unit and underneath the sheet of styrofoam. Note that outside temperatures may fluctuate dramatically, but the temperature underneath the styrofoam sheet remains relatively constant. The difference in temperature between inside and outside the unit can exceed at times 82˚F or 45˚ C.
94	January 14, 2003 Washington, Louisiana
95	January 15, 2003 Washington, Louisiana
96	January 16, 2003 Washington, Louisiana
97	Larvae at Minus 1˚ C
98	Conversion Rate Drop
99	Far Easier Than Imagined
100	Further Research
101	Heat of Summer
102	No Over-heating in Winter
103	Conclusion
104	The Best that Nature Has to Offer