The Feed Recycle Process (Anon. 1972e, 1973e; Senior, 1974) is a commercial process based on the separation of the basic contaminants of livestock waste (silicate and other mineral matter, fibre, cell-wall, lignin as well as other structural carbohydrates); it claims a recovery of 89% protein. The final product contains 20% crude protein, 6% crude fat and sugar, 19% starch, 37% cellulose and lignin, 6% salt and 12% free ash.
The Feed Recycle Process was originally designed for processing feedlot cattle waste, but it can be used for other types of livestock waste. The summary of the process published by the United States Environment Protection Agency (USEPA) (Feedlots 1974) gives the following economic data:
“Costs for a 100 t/day plant were calculated at $33.04/t treated, if operated at 25 t/day; $19.22 if operated at 50 t/day and $ 13.04 if operated at 100 t capacity. Values recovered per net tonne of manure (based on 140 kg crude protein, 36 kg ether extract and 440 kg of roughage) were $ 55.70/t. The maximum cash outlay was $350,000 at 85% operational capacity. It is contemplated that the plant would operate as a service unit processing manure which remains the property of the feedlot. At $35 per net dry tonne it is calculated that the plant would show a pre-tax profit of $510,000 per year and that the annual saving on feed would total $508,000.”
Development status
The system is technically feasible and fairly simple; it is being operated at a medium scale level. The economics of field operation are not available.
Health hazards
The system appears to be safe, but specific information is not available.
This aerobic process was originally designed for dairy waste, but it could be modified for all cattle wastes (Dale and Swanson, 1975). The mass balance for a 100-cow system is shown in Figure 9. The process recovers daily between 110 and 200 kg of forage containing 25% moisture and valued at $22/t.
The following data from a 100-cow system can be used as a basis for economic evaluation:
| Input: | tonnes/year |
| Total manure | 1.548 – 2.099 |
| Solids | 240 – 391 |
| Alum | 0.475 – 0.584 |
| Output: | |
| Roughage (on DM) | 54 – 97 |
| Fertilizer | unknown |
| Purified water | unknown |
| NH3 and CO2 | unknown |
The authors claim that the payback period is $6,200/yr/100-cow operation (Carlson, 1971). The Total Recycle Unit (TRU) is pre-assembled and weighs 636 kg. Operating weight is 1.4 t and power requirements 50 kw/day.
This process was originally designed for the treatment of cattle waste, but its use has now been extended to other livestock wastes (Seckler, 1975). Figure 10 illustrates the flow of the process. Animal wastes are processed to yield three products:
| Feedlot waste | Dairy waste | |
| Forage/silage | 30% | 30% |
| Protein feed | 30% | 45% |
| Humus/soil conditioner | 40% | 25% |
Investment (equipment, building, infrastructure), excluding land, for a confined beef herd project (12,000 animals) designed by Asia Research Pte. Ltd., was estimated (1975) to be M$1,784.00 (Malaysian dollar = about US$0.40 in 1975), with a projected income for the first 10 years as given in Table 97.
Figure 9 — The Biochemical Recycle Process
Figure 10 — The Cereco Process
Table 97
CERECO SYSTEM: PROJECTED STATEMENT OF INCOME
(1000 Malaysian dollars)
| Item | 1st yr | 2nd yr | 3rd yr | 4th - 10th yr (per year) |
| INCOME | ||||
| Sales of: | ||||
| Protein feed1 | 735.0 | 787.5 | 903.0 | 1,260.0 |
| Forage2 | 210.0 | 225.0 | 315.0 | 360.0 |
| Humus3 | 63.0 | 67.5 | 77.4 | 94.5 |
| Sub-total | 1,008.0 | 1,008.0 | 1,295.4 | 1,714.5 |
| Inflationary increase (10%) | - | 108.0 | 259.1 | 514.4 |
| GROSS INCOME | 1,008.0 | 1,188.0 | 1,554.5 | 2,228.9 |
| EXPENSES | ||||
| Total costs | 768.7 | 813.0 | 950.4 | 1,197.7 |
| Inflationary increase (10%) | - | 50.0 | 113.4 | 198.4 |
| TOTAL EXPENSES | 768.7 | 863.0 | 1,063.8 | 1,396.1 |
| NET INCOME (before tax) | 239.3 | 325.0 | 490.7 | 832.8 |
| NET INCOME (1975 real values) | 239.3 | 267.0 | 345.0 | 516.8 |
1 Based on 0.3 mature unit (MU)/year at M$350/t.
2 Based on 0.4 t/MU/year at M$75/t.
3 Based on 0.3 t/MU/year at M$30/t.
Source: Müller, 1977.
Development status
Several projects are currently operating, but the system is still under further development to improve the quality of “protein feed”, which still exhibits a high ash content (28–33%).
Reliability and applicability
The system is fairly reliable; it is economically applicable only for larger units (5,000 head of cattle). Attempts are being made to extend the system to other animal wastes.
Health hazards
The process appears to be completely safe.
This system is designed for both open feedlots and confinement housing of beef and dairy cattle. Its principle is the collection of liquid and solid wastes which are pumped into a vibrating screen and press to separate liquids from solids. The liquid effluent is discharged into a holding pond and applied as a crop fertilizer. Solids are either composted, ensiled or pasteurized in the so-called “Corral Pathocide Process”. The treated product can be directly refed either to the cow herd or, after mixing with conventional feeds from crops fertilized by the liquid effluent, to confined cattle.
Figure 11 illustrates the Corral system. The recovery data and economic analysis of the Corral Process in open feed lots with 5,000, 20,000 and 60,000 head of cattle are given in Tables 98 and 99.
Table 98
CORRAL SYSTEM: ESTIMATED RECOVERY
| Daily production | Size of operation (head of cattle) | |||
| 5,000 | 20,000 | 60,000 | ||
| Feed: tons | (DM) | 6 | 23 | 68 |
| Fertilizer: | N(kg) | 157 | 629 | 1,887 |
| P(kg) | 47 | 195 | 584 | |
| K(kg) | 166 | 665 | 1,996 | |
Assumptions: 364 kg av. animal wt., 8% body wt. daily excreta; 15% solids in excreta; 67% solids available; 70% collection efficiency; 50% machine recovery; N-3.08%; P-0.95%; K-3.25%.
Operating - 365 days.
Note: These data were developed from experiments and projections, and should be considered as broad indications only, subject to local variations.
Source: Corral, 1975.
Table 99
CORRAL SYSTEM: SUMMARY OF ECONOMIC DATA
| Item | Size of operation (head of cattle) | |||
| 5,000 | 20,000 | 60,000 | ||
| Annual operating cost1 | $'000 | 42.0 | 107.7 | 240.5 |
| Total profit (pre-tax) | $'000 | 101.4 | 466.2 | 1,480.2 |
| Investment cost | $'000 | 125.0 | 180.0 | 500.0 |
| Simple payout | years | 1.2 | 0.4 | 0.3 |
Note: Values, Phoenix, Arizona, USA, August 1975: N=50.6 ¢/kg; P=57.2¢/kg; K=48.4 ¢/kg; direct cost prorata: 50% feed, 50% fertilizer.
Source: Corral, 1975.
Development status
The Corral system is commercially applied, and independent tests carried out with 25% recycled solids as a replacement for a standard feed concentrate showed economic benefits (Bunger, 1974).
Health hazards
The system appears to be safe.
Kaplan Industries (1978) has developed a total nutrient recycling system in which cattle wastes are collected, washed and processed to separate fibrous solids and liquids.
The solids are treated and used as cattle roughage. The liquids, and processing plant wastes, flow to a lagoon system, where fermentation and algae growth occur. In the final lagoon, the algae serve as a feed for fish, which are harvested at a marketable price. The water is used partly for cattle and partly for irrigation of feed corps. Methane is a by-product of the system, produced in quantities sufficient to run the plant and supply the town of Bartow. The company has been developing a technique for separating carbon dioxide from biogas which could provide “much of Florida's dry ice” requirement.
Development status
The system is fully established, workable and practically applicable.
Health hazards
The process is safe.
Dew Fresh Eggs Corp, has introduced a completely closed recycling system based on poultry and cattle. The system recovers cattle and poultry wastes and converts them into usable products (feed, methane gas and fertilizer). The schematic flow of the system is illustrated in Figure 12.
The system involves replacement birds for layer facilities, confined cattle, replacement cattle held in pasture, a feed mill, a methane generator and cropping land. Poultry manure is partly utilized for methane and partly applied as a fertilizer; the liquid fraction of the cattle manure is used for methane, while the separated solid fraction is fed to replacement cattle.
The farm operates on 472 ha with a projected extension of 4,000 ha, 1.2 million layers, 500,000 pullets and 10,000 feedlot cattle. The methane gas output is estimated to be 35,000 m3; it is blended with natural gas in the utilities pipeline system. Biogas and conventional gas should completely substitute electricity, which will be used only for a back-up system. It is envisaged that the biogas investment will have a pay-back period of about 5 years.
Figure 11 — The Corral system
Figure 12 — The “Closed Ecological Cycle”
This process is only briefly mentioned (Feedlots, 1974). It was originally designed for poultry manure, but it can be modified for other animal wastes. The manure is separated into liquid and solid fractions. Uric acid, soluble proteins, antibiotics, heavy metals and other solubles migrate with the liquid fraction, while fibre, insoluble protein, ash and other, mostly undigestible, nutrients remain in the solid fraction. The latter is fortified with hatchery waste and after dehydration (4% moisture) it contains about 12% crude protein, 18% crude fibre, 5% ether extract and 30% ash. The high ash content limits the possibility of incorporation into rations. The relatively high crude fibre level limits the use of the product for monogastric animals. Figure 13 depicts the schematic flow of the process.
Langston of Midwest Research Institute, U.S.A., reported (Anon., 1971a) a manure recycling project involving 250,000 layers. Poultry manure, converted into a slurry, is heat treated and then subjected to fermentation for 36 hours. The biomass, being higher in protein and lower in undigestible material, can be recycled to poultry and other livestock either wet or dried. No ill effects were observed when the dried biomass was fed to chickens for several cycles.
The Grazon (1975) Process does not require special mechanical equipment. Fresh animal wastes are treated with a 37% formaldehyde solution (10 kg HCHO per tonne of manure (DM) and mixed in an auger-type mixer-blender. The product, called “Formulage”, can be fed immediately after mixing. If the moisture content of the mixture is 40% or less, it can be stored indefinitely under aerobic conditions; if the moisture is as high as 75% it must be fed to cattle within 10 days. Normally, the rest of the feed ingredients comprising the ration are added to the prepared waste after thorough mixing.
The savings produced by replacing forage with Formulage depend on the quantity used and the other ingredients comprising the ration. The company prodives simple mechanical metering units at a cost of $1,000. Formulage can be fed up to 50% for maintenance and up to 25% for finishing rations. The process is designed for cattle feedlots and is not practical for confinement facilities. where waste is in slurry form. The proprietor charges $1.00 per head/month for the use of the patented process (Larson, 1975).
Figure 13 — Chemical Extraction
The Organiform Process (Davies et al., 1975) converts manure into feed. The nitrogen content increases from 2% to 14% and the product can be used as a high-NPN concentrate for ruminants. Since urea-formaldehyde technology is applied, the product has a slow-release nitrogen and minimum toxicity as compared with direct feeding of untreated urea. The economic advantages of organiform processes are obvious, because the process enhances both the value of the carrier waste product and the added urea. The economics of this process can only be established under specific conditions of a feeding system. Data from commercial application are not available.
F. Kramer (British patent 1 314 783) patented a process in which poultry manure is liquified and absorbed in a small amount of urea-formaldehyde polymer foam. After incubation for fermentation and propagation of the micro-organisms contained in the manure, a practically dry product is obtained, which is free from odour and rich in protein of microbial origin. It can be used as protein supplement, particularly for ruminants.
A process for preparing a poultry feed from poultry excreta is described by the Boeing Company (Netherlands patent 721 6948). Poultry excreta is mixed with a liquid alkaline solution to dissolve the soluble constituents, and the solid phase is separated from the liquid phase. The solid phase, containing non-digested feed components, is mixed with ground egg shells and other hatchery by-products to produce a poultry feed. The liquid phase is used as a culture medium for bacteria to produce proteins which can be used as poultry feed supplements.
Chukei (USA patent 3,776,188) observed that offensive odours from the accumulation of manure in poultry houses can be substantially inhibited by the use of coarse powder of dried ferrous sulphate heptahydrate, dusting the floor of poultry houses with the active substance in advance. The powder was used in the form of a mixture with some fly ash or dried fine zeolite powder for ease of dusting. It was suggested that manure treated in this way can also be utilized as a feed for poultry, fish and ruminants.
